Article

The Rise of Skeletal Biominerals

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Abstract

The ability of organisms to synthesize skeletons and functional biomineral structures is one of the most remarkable events in the timeline of mineral evolution. The relatively abrupt rise of such forms in the fossil record marks the beginning of a new type of chemistry whereby biology develops a playbook of mineralization processes whose strategies scientists are only beginning to decipher. The first outlines of an impressive picture are emerging, in which the biochemical machinery and sequence of instructions that pass forward to subsequent generations are being defined. Yet, skeletons are anything but static in the transfer. The fossil record shows the dynamic responses of skeletal structures to shifts in environmental conditions over geologic time.

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... However, the morphologies and textures of apatite in bone and other hard tissues are extraordinarily complex, significantly departing from typical crystal habits of their geological counterparts. For example, in bone, a family of materials built up from mineralized collagen with highly complex intergrowths of apatite and organics, up to seven hierarchical levels of organisation have been identified (e.g., Boskey, 2007;Pasteris et al., 2008;Beniash et al., 2009;Dove, 2010). Crystal morphology in biominerals is key to their function, and is tightly controlled in many biomineralisation systems. ...
... For instance, the organic matrix that forms enamel is thought to regulate the shape and organisation of mineral particles (Fincham et al., 1999;Margolis et al., 2006), which consists of a number of proteins, with amelogenin, the major enamel protein, constituting more than 90 wt.% of the enamel matrix. On the other hand, biochemists have long recognised that the local solvation environment around biomolecules regulates the ability of calcium, and to some extent, magnesium to activate a variety of cellular functions (Dove, 2010), and there is recent evidence that the local solvation environment around biomolecules can also modulate mineralisation (Elhadj et al., 2006;Kowacz and Putnis, 2008;Stephenson et al., 2008;Dove, 2010). Moreover, physicochemical factors in a particular tissue or organ, such as calcium and phosphate concentrations, temperature, ionic strength, solution pH, and degree of supersaturation, are quite variable (Howell et al., 1960(Howell et al., , 1968Wuthier, 1969Wuthier, , 1971Lundgren and Linde, 1987;Larsson et al., 1988;Lundgren et al., 1992;Siqueira et al., 2012). ...
... For instance, the organic matrix that forms enamel is thought to regulate the shape and organisation of mineral particles (Fincham et al., 1999;Margolis et al., 2006), which consists of a number of proteins, with amelogenin, the major enamel protein, constituting more than 90 wt.% of the enamel matrix. On the other hand, biochemists have long recognised that the local solvation environment around biomolecules regulates the ability of calcium, and to some extent, magnesium to activate a variety of cellular functions (Dove, 2010), and there is recent evidence that the local solvation environment around biomolecules can also modulate mineralisation (Elhadj et al., 2006;Kowacz and Putnis, 2008;Stephenson et al., 2008;Dove, 2010). Moreover, physicochemical factors in a particular tissue or organ, such as calcium and phosphate concentrations, temperature, ionic strength, solution pH, and degree of supersaturation, are quite variable (Howell et al., 1960(Howell et al., , 1968Wuthier, 1969Wuthier, , 1971Lundgren and Linde, 1987;Larsson et al., 1988;Lundgren et al., 1992;Siqueira et al., 2012). ...
Article
Full-text available
Hydroxyapatite (HAP) with various morphologies was prepared, in the absence of biological or organic molecules, through an ammonia gas diffusion method at room temperature. Contrary to the common consensus that crystal morphology control of biominerals is generally achieved by biological or organic molecules, our results suggest that PO4 3− may also play a crucial role in the special morphogenesis of hydroxyapatite. The morphology, structure and composition of the obtained products were characterised by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The FESEM and TEM analyses demonstrate that at a given concentration of Ca2+, increasing PO4 3− concentration leads to the formation of hydroxyapatite with various morphologies ranging from porous flower-like spheres, hollow bur-like spheres to solid bur-like spheres. If the PO4 3 − concentration remains constant, however, the porous flower-like spheres are always obtained at different concentrations of Ca2+. For all concentrations of PO4 3−, a series of time-resolved experiments reveal that the initial precipitate is always unstable amorphous calcium phosphate (ACP), and that the generation of the different morphologies originates from the dissolution of amorphous calcium phosphate, followed by the crystallisation and self-assembly of hydroxyapatite. Possible mechanisms are proposed for the formation of HAP with the different shapes and architectures. The dependence of HAP morphology on phosphate concentration suggests that, in biomineralisation, biological genetic and physicochemical factors can cooperatively influence the formation of hydroxyapatite with unusual morphologies and hierarchical structures.
... However, the morphologies and textures of apatite in bone and other hard tissues are extraordinarily complex, significantly departing from typical crystal habits of their geological counterparts. For example, in bone, a family of materials built up from mineralized collagen with highly complex intergrowths of apatite and organics, up to seven hierarchical levels of organisation have been identified (e.g., Boskey, 2007;Pasteris et al., 2008;Beniash et al., 2009;Dove, 2010). Crystal morphology in biominerals is key to their function, and is tightly controlled in many biomineralisation systems. ...
... For instance, the organic matrix that forms enamel is thought to regulate the shape and organisation of mineral particles (Fincham et al., 1999;Margolis et al., 2006), which consists of a number of proteins, with amelogenin, the major enamel protein, constituting more than 90 wt.% of the enamel matrix. On the other hand, biochemists have long recognised that the local solvation environment around biomolecules regulates the ability of calcium, and to some extent, magnesium to activate a variety of cellular functions (Dove, 2010), and there is recent evidence that the local solvation environment around biomolecules can also modulate mineralisation (Elhadj et al., 2006;Kowacz and Putnis, 2008;Stephenson et al., 2008;Dove, 2010). Moreover, physicochemical factors in a particular tissue or organ, such as calcium and phosphate concentrations, temperature, ionic strength, solution pH, and degree of supersaturation, are quite variable (Howell et al., 1960(Howell et al., , 1968Wuthier, 1969Wuthier, , 1971Lundgren and Linde, 1987;Larsson et al., 1988;Lundgren et al., 1992;Siqueira et al., 2012). ...
... For instance, the organic matrix that forms enamel is thought to regulate the shape and organisation of mineral particles (Fincham et al., 1999;Margolis et al., 2006), which consists of a number of proteins, with amelogenin, the major enamel protein, constituting more than 90 wt.% of the enamel matrix. On the other hand, biochemists have long recognised that the local solvation environment around biomolecules regulates the ability of calcium, and to some extent, magnesium to activate a variety of cellular functions (Dove, 2010), and there is recent evidence that the local solvation environment around biomolecules can also modulate mineralisation (Elhadj et al., 2006;Kowacz and Putnis, 2008;Stephenson et al., 2008;Dove, 2010). Moreover, physicochemical factors in a particular tissue or organ, such as calcium and phosphate concentrations, temperature, ionic strength, solution pH, and degree of supersaturation, are quite variable (Howell et al., 1960(Howell et al., , 1968Wuthier, 1969Wuthier, , 1971Lundgren and Linde, 1987;Larsson et al., 1988;Lundgren et al., 1992;Siqueira et al., 2012). ...
Article
Hydroxyapatite (HAP) with various morphologies was prepared, in the absence of biological or organic molecules, through an ammonia gas diffusion method at room temperature. Contrary to the common consensus that crystal morphology control of biominerals is generally achieved by biological or organic molecules, our results suggest that PO43- may also play a crucial role in the special morphogenesis of hydroxyapatite. The morphology, structure and composition of the obtained products were characterised by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The FESEM and TEM analyses demonstrate that at a given concentration of Ca2+, increasing PO43- concentration leads to the formation of hydroxyapatite with various morphologies ranging from porous flower-like spheres, hollow bur-like spheres to solid bur-like spheres. If the PO43- concentration remains constant, however, the porous flower-like spheres are always obtained at different concentrations of Ca2+. For all concentrations of PO43-, a series of time-resolved experiments reveal that the initial precipitate is always unstable amorphous calcium phosphate (ACP), and that the generation of the different morphologies originates from the dissolution of amorphous calcium phosphate, followed by the crystallisation and self-assembly of hydroxyapatite. Possible mechanisms are proposed for the formation of HAP with the different shapes and architectures. The dependence of HAP morphology on phosphate concentration suggests that, in biomineralisation, biological genetic and physicochemical factors can cooperatively influence the formation of hydroxyapatite with unusual morphologies and hierarchical structures.
... This striking colouration is preserved in specimens as old as 18 Ma and suggests the possibility that biomolecular fossils of shell-binding proteins and associated pigments might be preserved. Protein and polysaccharides are known to be important components of mollusk shell architecture; they form the organic matrix upon which the calcite and/or aragonite crystallises (Marin et al., 2008;Mann, 2001;Weiner et al., 1984;Dove, 2010). The organic shell-binding matrix forms sheets ~30 nm in thickness between which the minerals crystallise (Mann, 2001). ...
... Dissolved calcitic portions of Ecphora yield significant amounts (≥ 3 mg per gram) of a polymeric substance with an orange-brown colour similar to that of the in situ fossil shell material. Microscopic and SEM imaging reveals that this residual material forms thin (≤ 30 nm) flexible sheets with maximum dimensions to ~ 1 cm (Fig. 2) -characteristics consistent with modern molluscan shell-binding proteins (Marin et al., 2008;Mann, 2001;Weiner et al., 1984;Dove, 2010). In addition, SEM images and analyses of broken shell material reveal thin organic sheets visible on fractured surfaces of the calcitic (but not aragonitic) portions of Ecphora shells. ...
Article
Full-text available
doi: 10.7185/geochemlet.1501 The genus Ecphora of Muricid gastropods from the mid-Miocene Calvert Cliffs, Maryland is characterised by distinct reddish-brown colouration that results from shell-binding proteins associated with pigments within the outer calcite (CaCO3) portion of the shell. The mineral composition and robustness of the shell structure make Ecphora unique among the Neogene gastropods. Acid-dissolved shells produce a polymeric sheet-like organic residue of the same colour as the initial shell. NMR analysis indicates the presence of peptide bonds, while hydrolysis of the polymeric material yields 11 different amino acid residues, including aspartate and glutamate, which are typical of shell-binding proteins. Carbon and nitrogen elemental and isotopic analyses of the organic residue reveals that total organic carbon ranges from 4 to 40 weight %, with 11 < C/Nat < 18. Isotope values for carbon (-17 < δ 13 C < -15‰) are consistent with a shallow marine environment, while values for nitrogen (4 < δ 15
... Much attention has focused on the biological nano-sculpting of mineral-organic composite materials that play structural roles in organisms. Examples include hydroxylapatite and fluorapatite in directed biomineralization of vertebrates (teeth and bones), inarticulate brachiopod shells, and stinging nettles; the calcite or aragonite forms of CaCO 3 , for example in corals, mollusks, and foraminifera; and of silica employed by such diverse organisms as diatoms, sponges, and spinifex grass (Lowenstam and Weiner 1989;Weiner and Wagner 1998;Dove et al. 2003;Dove 2010;Aparicio and Ginebra 2016;Ensikat et al. 2016;Kattimani et al. 2016;Endo et al. 2018). Lichtenegger et al. (2002) also reported an unusual occurrence of atacamite [Cu 2 (OH) 3 Cl] in jaws of the bloodworm, Glycera dibranchiate. ...
Article
A systematic survey of 57 different paragenetic modes distributed among 5659 mineral species reveals patterns in the diversity and distribution of minerals related to their evolving formational environments. The earliest minerals in stellar, nebular, asteroid, and primitive Earth contexts were dominated by relatively abundant chemical elements, notably H, C, O, Mg, Al, Si, S, Ca, Ti, Cr, and Fe. Significant mineral diversification subsequently occurred via two main processes, first through gradual selection and concentration of rarer elements by fluid-rock interactions (for example, in hydro-thermal metal deposits, complex granite pegmatites, and agpaitic rocks), and then through near-surface biologically mediated oxidation and weathering. We find that 3349 mineral species (59.2%) are known from only one paragenetic context, whereas another 1372 species (24.2%) are associated with two paragenetic modes. Among the most genetically varied minerals are pyrite, albite, hornblende, corundum, magnetite, calcite, hematite, rutile, and baryte, each with 15 or more known modes of formation. Among the most common paragenetic modes of minerals are near-surface weathering/oxidation (1998 species), subsurface hydrothermal deposition (859 species), and condensation at volcanic fumaroles (459 species). In addition, many species are associated with compositionally extreme environments of highly differentiated igneous lithologies, including agpaitic rocks (726 species), complex granite pegmatites (564 species), and carbonatites and related carbonate-bearing magmas (291 species). Biological processes lead to at least 2707 mineral species, primarily as a consequence of oxidative weathering but also through coal-related and other taphonomic minerals (597 species), as well as anthropogenic minerals, for example as byproducts of mining (603 minerals). However, contrary to previous estimates, we find that only ~34% of mineral species form exclusively as a consequence of biological processes. By far the most significant factor in enhancing Earth’s mineral diversity has been its dynamic hydrological cycle. At least 4583 minerals—81% of all species—arise through water-rock interactions. A timeline for mineral-forming events suggests that much of Earth’s mineral diversity was established within the first 250 million years. If life is rare in the universe, then this view of a mineralogically diverse early Earth provides many more plausible reactive pathways over a longer timespan than previous models. If, however, life is a cosmic imperative that emerges on any mineral- and water-rich world, then these findings support the hypothesis that life on Earth developed rapidly in the early stages of planetary evolution.
... Approximately two-thirds of the organisms formed phosphate skeletons, and the remainder third formed their skeletons with calcium; but in less than 20 million years the proportions changed and more than half of the living organisms have their skeletons built from calcium carbonate, with the calcite formation being the most used [82]. Currently, the skeletons of living organisms use three main minerals: calcium carbonates, phosphates, and silicon, the first ones dominate in the biological systems, preserved since the origins of biomineralization until this date, and coinciding with the minerals from which biomorphs can be obtained nowadays [83]. Likewise, biomorphs are key elements in the study of other disciplines, for example, they have been very important to understand how the biomineralization processes occur, and how this knowledge can be applied for the design and fabrication of new generation nanomaterials [84]. ...
Article
As known currently, in the formation of the Earth, minerals have played a pivotal role going from the formation of the hydrosphere, the lithosphere, and all Earth components until the origin, evolution, and maintenance of life. The first signs of magnetism are found in komatiites. In the origin of life, minerals were responsible for concentrating, aligning, and acting as templates and catalyzers, allowing for the formation of bonds among the first biomolecules to form polymers, which eventually became assembled to give rise to the pioneer organism in the Precambrian. Besides, minerals allowed the DNA to be the information storing molecule, even though it was not the first biomolecule. Another function of minerals was to protect the organic complexes against ultraviolet radiation and hydrolysis, a fundamental action to preserve life in the Precambrian where high UV radiation prevailed. Minerals not only favored the origin of life but also became part of the organisms that inhabit the Earth, including species of the five kingdoms, comprising from microorganisms to higher organisms. How minerals participated in the origin of life still has unresolved questions, for which to understand the minerals’ participation since the formation of the Earth until becoming part of the structure of organisms from the five kingdoms, we reviewed the following topics, which will contribute to the understanding of the implication of minerals in the origin of our planet and life on it: i) the synthesis of the chemical elements from which the first mineral were obtained in the Earth, ii) the factor that favored the formation of minerals in the Earth, iii) the implication of minerals as the basis for the synthesis of the first biomolecule and, eventually, the pioneer organism, as well as the biomineralization mechanism that has been proposed to account for the mineral part contained in the structure of the organisms from the different kingdoms, and iv) the models that allow emulating the mechanisms by which minerals participated in the synthesis of the first biomolecule; in this way, for example, the Precambrian microfossils are so simple morphologically (spheres, subspheres, and hemispheres) that they can easily be imitated by hollow mineral growths, known as biomorphs. Although these can interfere with the study of actual microfossils, they remain as key points for the study of the origin of life.
... Much attention has focused on the biological nano-sculpting of mineral-organic composite materials that play structural roles in organisms. Examples include hydroxylapatite and fluorapatite in directed biomineralization of vertebrates (teeth and bones), inarticulate brachiopod shells, and stinging nettles; the calcite or aragonite forms of CaCO 3 , for example in corals, mollusks, and foraminifera; and of silica employed by such diverse organisms as diatoms, sponges, and spinifex grass (Lowenstam and Weiner 1989;Weiner and Wagner 1998;Dove et al. 2003;Dove 2010;Aparicio and Ginebra 2016;Ensikat et al. 2016;Kattimani et al. 2016;Endo et al. 2018). Lichtenegger et al. (2002) also reported an unusual occurrence of atacamite [Cu 2 (OH) 3 Cl] in jaws of the bloodworm, Glycera dibranchiate. ...
... Varying levels of biological control on biomineralization are apparent across the phyla studied when assessing elements individually (Figures 1, 3; Dove, 2010). However, clear groupings of species arise when evaluating the elemental ratios together (Figures 4-6). ...
Article
Full-text available
Elemental ratios in biogenic marine calcium carbonates are widely used in geobiology, environmental science, and paleoenvironmental reconstructions. It is generally accepted that the elemental abundance of biogenic marine carbonates reflects a combination of the abundance of that ion in seawater, the physical properties of seawater, the mineralogy of the biomineral, and the pathways and mechanisms of biomineralization. Here we report measurements of a suite of nine elemental ratios (Li/Ca, B/Ca, Na/Ca, Mg/Ca, Zn/Ca, Sr/Ca, Cd/Ca, Ba/Ca, and U/Ca) in 18 species of benthic marine invertebrates spanning a range of biogenic carbonate polymorph mineralogies (low-Mg calcite, high-Mg calcite, aragonite, mixed mineralogy) and of phyla (including Mollusca, Echinodermata, Arthropoda, Annelida, Cnidaria, Chlorophyta, and Rhodophyta) cultured at a single temperature (25°C) and a range of pCO2 treatments (ca. 409, 606, 903, and 2856 ppm). This dataset was used to explore various controls over elemental partitioning in biogenic marine carbonates, including species-level and biomineralization-pathway-level controls, the influence of internal pH regulation compared to external pH changes, and biocalcification responses to changes in seawater carbonate chemistry. The dataset also enables exploration of broad scale phylogenetic patterns of elemental partitioning across calcifying species, exhibiting high phylogenetic signals estimated from both uni- and multivariate analyses of the elemental ratio data (univariate: λ = 0–0.889; multivariate: λ = 0.895–0.99). Comparing partial R² values returned from non-phylogenetic and phylogenetic regression analyses echo the importance of and show that phylogeny explains the elemental ratio data 1.4–59 times better than mineralogy in five out of nine of the elements analyzed. Therefore, the strong associations between biomineral elemental chemistry and species relatedness suggests mechanistic controls over element incorporation rooted in the evolution of biomineralization mechanisms.
... The elemental composition of the carbonate skeleton can provide records of seawater chemistry and has a significant potential for the fields of palaeoceanography and palaeoclimatology (Freitas et al., 2006;Gillikin et al., 2006;Khim et al., 2003;Ponnurangam et al., 2016;Vander Putten et al., 2000). However, as recent studies have indicated (Dove, 2010), the influence of environmental parameters on shell precipitation could be very complex. The mineralogy and chemistry of shells are likely to be both linked to environmental conditions and controlled by the organism itself. ...
Article
Full-text available
The shells of calcitic arthropod Amphibalanus improvisus; aragonitic bivalves Cerastoderma glaucum, Limecola balthica, and Mya arenaria; and bimineralic bivalve Mytilus trossulus were collected in the brackish waters of the southern Baltic Sea in order to study patterns of bulk elemental concentration (Ca, Na, Sr, Mg, Ba, Mn, Cu, Pb, V, Y, U and Cd) in shells composed of different crystal lattices (calcite and aragonite). The factors controlling the elemental composition of shells are discussed in the context of crystal lattice properties, size classes of organisms and potential environmental differences between locations. Clams that precipitate fully aragonitic shells have a clear predominance of Sr over Mg in shells, contrary to predominant accumulation of Mg over Sr in calcitic shells of barnacles. However, the barnacle calcite shell contains higher Sr concentration than bivalve aragonite. The elemental variability between size-grouped shells is different for each studied species, and the elemental concentrations tend to be lower in the large size classes compared to the smaller size classes. Biological differences between and within species, such as growth rate, feeding strategy (including feeding rate and assimilation efficiency or composition) and contribution of organic material, seem to be important factors determining the elemental accumulation in shells. Because specimens used in this study were obtained from different sampling sites within the gulf, the impact of location-specific environmental factors, such as sediment type, cannot be excluded.
... Likewise, quartz displays multiple kinds: in granite and granite pegmatite, in hydrothermal veins, in quartzite, and in the biosilica of diatom skeletons (Heaney et al. 1994;Wysokowski et al. 2018). Pyrite differs in polymetallic veins, in black shales, and pyritized brachiopods (Rickard 2015); while calcite occurs in abiotic precipitates, biomineralized shells, and a dozen other contexts (Reeder 1983;Dove 2010). ...
Article
Full-text available
Minerals reveal the nature of the co-evolving geosphere and biosphere through billions of years of Earth history. Mineral classification systems have the potential to elucidate this rich evolutionary story; however, the present mineral taxonomy, based as it is on idealized major element chemistry and crystal structure, lacks a temporal aspect, and thus cannot reflect planetary evolution. A complementary evolutionary system of mineralogy based on the quantitative recognition of “natural kind clustering” for a wide range of condensed planetary materials with different paragenetic origins has the potential to amplify, though not supersede, the present classification system.
... Despite their importance in the carbonate budget, very little is known about calcification processes in bryozoans comparatively to other groups of biomineralisers (Dove, 2010;. Θ Calcimass percentage (i.e. the portion of volume that is calcified) ...
Thesis
Full-text available
Cheilostomatous bryozoans are biomineralisers, as such, vulnerable to acidification and increasing temperature currently affecting the world’s oceans. Cheilostomes have excelled in zooid polymorphism and they also perform a high array of growth forms, geometries and mineralogies. Flustriforms, and related taxa, are considerably speciose, ubiquitous, and highly abundant in the benthic realm. An extensive literature review coupled with the analysis of spatial distribution data was performed to address growth as a fundamental biological process of multidimensional expressions. Growth can manifest in zooidal production, somatic growth (both zooids and colonial) and area. However, a more comparable, albeit requiring additional analyses is the measurement of calcification (carbonate production). When temporal dimension is considered, growth is expressed as rates. At wider temporal scales, growth can be expressed via carbon immobilisation (secondary production) and sequestration, whereas, at wider spatial scales, growth can be measured by the expanding distribution ranges. Higher temperatures are expected to accelerate metabolism, hence growth rates, but will affect calcification. Broadly, near-future predicted scenarios will likely increase growth in flustrines in most dimensions addressed in this thesis. Evaluating these trends in a polar-temperate gradient will provide important insights of the underlying mechanisms and possible ecological trade-offs in cheilostomatous bryozoans.
... This process may be modified via the addition of impurities leading to changes in the crystallization pathway (nucleation, growth and/or aggregative processes) [2,3]. Biomineralization [4] (the ability of living organisms to mediate mineral formation) is a hugely important and widespread process that can be seen in everyday materials such as bone [5], teeth [5], skeletal tissues in sponges [6], crustaceans [7], egg shells [8], mollusc shells [9] and calcium oxalate is a known biomineral that contributes to urolithiasis [10]. Calcium oxalate makes up approximately 70% of kidney stones while other components are calcium phosphate~8.9%, ...
Article
Cystallization of calcium oxalate monohydrate was investigated in the presence of various organic molecules in combination with zinc ions. This work looked at the impacts at physiological pHs (6–8) and temperature (37 °C). It was found that the number of carboxylate and hydroxyl groups was critical in determining the degree of inhibition. This inhibition was found to be mainly due to the ability of the organics to chelate with calcium ions. Zinc ions were found to chelate with oxalate ions leading to lower nucleation rates, but this is not strictly inhibition but a lowering of the supersaturation due to lowering of the activity of the oxalate. Organics have variable impact depending on whether the zinc ions or calcium ions preferentially chelate with the organic.
... The calcification process includes a broad spectrum of factors controlling precipitation. Although the type of mineral composition in organisms is mainly biologically and genetically controlled (Watabe and Wilbur 1960;Addadi and Weiner 1992;Belcher et al. 1996, Dove 2010, Tambutté et al. 2012, environmental physical-chemical factors (e.g. temperature, salinity) also affect its properties (Dodd 1965;Lorens and Bender 1980;Bourgoin 1990;Pitts and Wallace 1994;Klein et al. 1996aKlein et al. , 1996b. ...
Conference Paper
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In many areas of the world ocean bryozoans are important carbonate producers. Evidence suggests that in colder high-latitude marine environments most bryozoan species precipitate in most cases low-magnesium calcite (≤4 mol% MgCO3) carbonate skeletons, while secretion of aragonite and high-magnesium calcite (≥12 mol% MgCO3) is largely restricted to warmer low-latitude waters. Although such a pattern seems to exist, it is not robustly confirmed by empirical data. This study explores the mineralogical composition of bryozoans along the Aleutian Islands to examine the mineralogical variability of skeletons precipitated in the transition zone between temperate and Arctic areas. The mineralogical investigation of 120 bryozoan samples from the Aleutian Islands indicates that 117 skeletons are built of calcite and three of mixed calcite and aragonite layers with magnesium content in calcite ranging from 2.2 to 8.0 mol% MgCO3. The mineralogical profile of Aleutian bryozoans is consistent with the increasing solubility of aragonite and high-magnesium calcite with decreasing water temperature. A high variability of Mg content in calcite within and among species is most likely caused by species-specific physiological features. In a global context, this study confirms the latitudinal pattern in bryozoan mineralogy and indicates environment as an important factor controlling the calcification process.
... Likewise, quartz displays multiple kinds: in granite and granite pegmatite, in hydrothermal veins, in quartzite, and in the biosilica of diatom skeletons (Heaney et al. 1994;Wysokowski et al. 2018). Pyrite differs in polymetallic veins, in black shales, and pyritized brachiopods (Rickard 2015); while calcite occurs in abiotic precipitates, biomineralized shells, and a dozen other contexts (Reeder 1983;Dove 2010). ...
... Although aragonite is the least stable of these minerals, and undergoes rapid recrystallization to thermodynamically more stable forms, it has been recognized as a fundamental constituent of marine depositional environments since at least the Archean (Sumner and Grotzinger 2004), and represents a primary shallow-marine depositional facies throughout the Proterozoic (Grotzinger and Read 1983; Bartley and Kah 2004;Kah and Bartley 2011). Furthermore, since the onset of enzymatic (a) (b) 28 Hazen,Downs,Jones,Kah Carbon Mineralogy & Crystal Chemistry 29 biomineralization, more than 500 million years ago, aragonite has been a primary constituent of the fossil record, forming metastable skeletons of some calcareous algae (Bathurst 1976) as well as the skeletal components of a variety of invertebrates, including a wide variety of molluscs, scleractinian corals, and some bryozoans (Cloud 1962;Rucker and Carver 1969;Knoll 2003;Dove 2010). Three other aragonite group minerals, the Sr, Ba, and Pb carbonates strontianite, witherite, and cerussite, respectively, are all found primarily in relatively low-temperature hydrothermal or supergene environments, commonly associated with sulfates and metal sulfide ores (Smith 1926;Mitchell and Pharr 1961;Mamedov 1963;Speer 1977;Dunham and Wilson 1985;Wang and Li 1991). ...
... Biomineralization is the most common process of mineral deposition by living organisms and can be found in all kingdoms of life. This process allows an organism to take up ions from the environment and incorporate them into functional structures that are useful for mechanical support (skeletons) and protection (shells) and that allow magnetotaxis (magnetosomes) (Mann, 2001;Lowenstam & Weiner, 1989;Dove, 2010). ...
Article
Full-text available
Biomineralization is the process of mineral formation by organisms and involves the uptake of ions from the environment in order to produce minerals, with the process generally being mediated by proteins. Most proteins that are involved in mineral interactions are predicted to contain disordered regions containing large numbers of negatively charged amino acids. Magnetotactic bacteria, which are used as a model system for iron biomineralization, are Gram-negative bacteria that can navigate through geomagnetic fields using a specific organelle, the magnetosome. Each organelle comprises a membrane-enveloped magnetic nanoparticle, magnetite, the formation of which is controlled by a specific set of proteins. One of the most abundant of these proteins is MamC, a small magnetosome-associated integral membrane protein that contains two transmembrane α-helices connected by an ∼21-amino-acid peptide. In vitro studies of this MamC peptide showed that it forms a helical structure that can interact with the magnetite surface and affect the size and shape of the growing crystal. Our results show that a disordered structure of the MamC magnetite-interacting component (MamC-MIC) abolishes its interaction with magnetite particles. Moreover, the size and shape of magnetite crystals grown in in vitro magnetite-precipitation experiments in the presence of this disordered peptide were different from the traits of crystals grown in the presence of other peptides or in the presence of the helical MIC. It is suggested that the helical structure of the MamC-MIC is important for its function during magnetite formation.
... Of all the biominerals, carbonates and phosphates are the most studied due to their abundance and structural functions in animals and humans. However, among the other materials receiving increasing attention are silica in diatoms (11); iron oxohydroxides and sulfides produced by bacteria, leading to the deposition of iron in the environment (12); and oxalates due to the formation of kidney stones. ...
Article
Biominerals are crucial materials that play a vital role in many forms of life. Understanding the various steps through which ions in aqueous environment associate to form increasingly structured particles that eventually transform into the final crystalline or amorphous poly(a)morph in the presence of biologically active molecules is therefore of great significance. In this context, computer modeling is now able to provide an accurate atomistic picture of the dynamics and thermodynamics of possible association events in solution, as well as to make predictions as to particle stability and possible alternative nucleation pathways, as a complement to experiment. This review provides a general overview of the most significant computational methods and of their achievements in this field, with a focus on calcium carbonate as the most abundant biomineral.
... Whichever crystal growth mechanism is employed by biominerals, the chemistry of the calcification environment has the potential to significantly alter the B uptake. Organisms exhibit varying degrees of control over the chemistry of calcification, ranging from external, biologically facilitated mineralisation by relatively simple bacteria, to the controlled production of specific mineral structures in tightly controlled, internal environments by complex metazoans (Dove 2010;Knoll 2003). To produce a mineral structure, organisms must either elevate the saturation state of seawater by increasing the concentration of Ca 2+ or CO 3 2− , or removing inhibitory Mg 2+ (Berner 1975) and organic components (Walter and E.A. Burton 1986) from seawater. ...
Chapter
The isotopic composition (δ¹¹B) and abundance (B/Ca) of boron in the marine CaCO3 minerals calcite and aragonite are used as paleoceanographic tracers for past oceanic pH and carbon chemistry. These environmental proxies depend upon the ability of CaCO3 minerals to incorporate trace concentrations of B within their structure, and record the state of the pH-dependent equilibrium between B(OH)3 and B(OH)4 {{{\text{B}}\left( {\text{OH}} \right)_{4}}^{ - }} , and the relative abundance of B and C in seawater. To achieve this CaCO3 minerals must either incorporate a single species of aqueous B, or take up a predictable mixture of both species. Initial investigations found evidence to suggest the sole incorporation of aqueous B(OH)4 {{{\text{B}}\left( {\text{OH}} \right)_{4}}^{ - }} into the anion site of CaCO3 minerals. These observations established the required link between aqueous B chemistry and CaCO3– hosted B, and provided the foundation for the development and application of the δ¹¹B and B/Ca proxies. However, advances in our understanding of aqueous B chemistry, improvements in the accuracy of B isotopic measurements of carbonates, and new data from controlled precipitation experiments have since revealed more complex, structure-dependent mechanisms of B incorporation into CaCO3. Studies of aragonite appear to support a relatively straightforward substitution of B(OH)4 {{{\text{B}}\left( {\text{OH}} \right)_{4}}^{ - }} into the mineral anion site. Conversely, a growing number of studies of calcite suggest either that both aqueous B(OH)3 and B(OH)4 {{{\text{B}}\left( {\text{OH}} \right)_{4}}^{ - }} are taken up into the mineral, or that B is subject to a significant isotopic fractionation during incorporation. While a growing body of theoretical and experimental work are moving toward an understanding of B uptake in CaCO3, we currently lack a systematic description of this key process, particularly in calcite. As long as the mechanisms of B incorporation remain unknown, the relationships between δ¹¹B and B/Ca and ocean chemistry must be treated as empirical, adding uncertainty to the paleoceanographic records derived from them. This chapter will explore our current understanding of B incorporation into marine CaCO3 minerals, in context of their structure and growth mechanisms. We will consider the broad question of ‘how does B get from seawater into calcite and aragonite?’
... [3][4][5][6][7][8] The structure and function of the intra-skeletal OM of scleractinian corals have been investigated in details in vivo and in vitro systems, letting to recognize its fundamental role in controlling the calcification process. 1,3,4,[8][9][10][11] OM composition varies with coral taxon 12,13 and is species specific, 9,11 but exhibits common chemical features. They are the presence of acidic glycoproteins having residues carrying carboxylate groups, 14 of polysaccharides often functionalized with sulphate groups 15,16 and of lipids. ...
Article
Recent research studies have shown that the intra-skeletal organic matrix of corals contains lipids. This communication reports their characterization and their influence on calcium carbonate precipitation. In addition, their potential role in coral's biomineralization is discussed.
... It has been shown (in situ and experimentally) that changes in environmental factors, particularly temperature and pH, influence the maintenance of the carbonate structures of bryozoans (Lombardi et al. 2011(Lombardi et al. , 2013Pistevos et al. 2011). However, along with a few recent comprehensive studies Dove 2010;Tambutté et al. 2012), the influence of environmental parameters on the specific biomineralogy and magnesium content is not clear. There is significant debate about the processes involved in biologically controlled mineralization . ...
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Bryozoans represent an extremely diversified phylum in terms of biomineralogy. The mineral composition of the bryozoan skeleton is most likely controlled by the organism itself and to some degree by the ambient environmental conditions (e.g., pH, Mg/Ca ratio, temperature). The purpose of this study is to describe the mineral composition of nearly one-quarter of all Antarctic bryozoan species known to date and to discuss, locally and in a global context, the potential factors that control mineralization in bryozoan skeletons. Collections of bryozoans were gathered by divers and with van Veen grabs (0.1 m2) from depths of 6–300 m at King George Island, Antarctica, during the summer seasons of 1985, 2007, and 2011. An x-ray diffraction analysis of the skeletons indicated that all analyzed Antarctic bryozoans (256 individuals, 71 taxa) precipitated monomineral calcite skeletons. The magnesium content ranged from 0.2 to 10.1 mol% MgCO3. Most of the studied species (76%) consisted of intermediate-magnesium calcite. Yet extreme variations in mol% MgCO3 were found between individuals of the same species as well as between species and populations. The high variability found between specimens of the same species suggests that the mol% MgCO3 could be determined by the biology or physiology of an individual. The magnesium content was equally distributed in each of three growth forms (e.g., erect flexible, erect rigid, and encrusting). The mean mol% MgCO3 in Antarctic species was significantly lower than that in bryozoans from Mediterranean, Chile, and New Zealand but similar to that in Arctic bryozoans. This finding confirms the latitudinal-pattern hypothesis of a decreased Mg content toward polar regions.
... However, more varied carbon minerals, including extensive carbonate formations precipitated by microbial communities (Walter et al. 1980;Sumner 1997;Grotzinger and Knoll 1999;Allwood et al. 2006;Lepot et al. 2008), and other C-bearing minerals found in Archean rocks older than 2.5 billion years (Hazen 2013), may differentiate Earth from many other astronomically "Earth-like" planets. Subsequent biological processes have led to numerous additional carbonate and organic mineral phases, both through biomineralization (Runnegar 1987;Warthmann et al. 2000;Mann 2001;Dove et al. 2003;Lee et al. 2007;Dove 2010) and as a consequence of atmospheric oxygenation (Hazen et al. 2008;Sverjensky and Lee 2010;Canfield 2014;Lyons et al. 2014). Most of the 403 carbon minerals approved by the International Mineralogical Association (IMA) as of 1 January 2015 (http:// rruff.info/ima) ...
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Studies in mineral ecology exploit mineralogical databases to document diversity-distribution relationships of minerals—relationships that are integral to characterizing “Earth-like” planets. As carbon is the most crucial element to life on Earth, as well as one of the defining constituents of a planet’s near-surface mineralogy, we focus here on the diversity and distribution of carbon-bearing minerals. We applied a Large Number of Rare Events (LNRE) model to the 403 known minerals of carbon, using 82 922 mineral species/locality data tabulated in http://mindat.org (as of 1 January 2015). We find that all carbon-bearing minerals, as well as subsets containing C with O, H, Ca, or Na, conform to LNRE distributions. Our model predicts that at least 548 C minerals exist on Earth today, indicating that at least 145 carbon-bearing mineral species have yet to be discovered. Furthermore, by analyzing subsets of the most common additional elements in carbon-bearing minerals (i.e., 378 C + O species; 282 C + H species; 133 C + Ca species; and 100 C + Na species), we predict that approximately 129 of these missing carbon minerals contain oxygen, 118 contain hydrogen, 52 contain calcium, and more than 60 contain sodium. The majority of these as yet undescribed minerals are predicted to be hydrous carbonates, many of which may have been overlooked because they are colorless, poorly crystalized, and/or water-soluble. We tabulate 432 chemical formulas of plausible as yet undiscovered carbon minerals, some of which will be natural examples of known synthetic compounds, including carbides such as calcium carbide (CaC2), crystalline hydrocarbons such as pyrene (C16H10), and numerous oxalates, formates, anhydrous carbonates, and hydrous carbonates. Many other missing carbon minerals will be isomorphs of known carbon minerals, notably of the more than 100 different hydrous carbonate structures. Surveys of mineral localities with the greatest diversity of carbon minerals, coupled with information on varied C mineral occurrences, point to promising locations for the discovery of as yet undescribed minerals.
... Biominerals are a special class of minerals produced by living organisms for a variety of biological functions, such as protection and mechanical support [1][2]. They have been in existence since the Cambrian period (about 540 million years ago). ...
Article
Statement of significance: Nacre is the iridescent inner lining of many mollusk shells, consisting of more than 95 wt% aragonite tablets and minor biopolymers. Owing to its superior mechanical properties, nacre has been extensively studied. However, nearly all previous works focused on the flat tablets. Here, we focus on the curved tablets grown on the wavy substrate. The main finding is that the topography and strain of the substrate play key roles in the growth process of the tablets. They not only induce the shape transition of the tablets from pyramids to dome-capped prisms, but also control the final shape of the tablets. The finding advances our understanding of the biomineralization process of nacre.
... These further modified the mineral inventory of Earth, although more in terms of pattern, relative abundance and distribution than in any substantial further increase in new minerals. The sophisticated and intricate patterns in biomineralized structures such as bivalve shells, diatom tests and echinoderm plates (Dove 2010), for instance, and the volume and complexity of reef limestones, have made the strata of the last halfbillion years of Earth history clearly distinctive. ...
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The Earth has shown a systematic increase in mineral species through its history, with three 'eras' comprising ten 'stages' identified by Robert Hazen and his colleagues (Hazen et al. 2008), the eras being associated with planetary accretion, crust and mantle reworking and the influence of life, successively. We suggest that a further level in this form of evolution has now taken place of at least 'stage' level, where humans have engineered a large and extensive suite of novel, albeit not formally recognized minerals, some of which will leave a geologically significant signal in strata forming today. These include the great majority of metals (that are not found natively), tungsten carbide, boron nitride, novel garnets and many others. A further stratigraphic signal is of minerals that are rare in pre-industrial geology, but are now common at the surface, including mullite (in fired bricks and ceramics), ettringite, hillebrandite and portlandite (in cement and concrete) and 'mineraloids' (novel in detail) such as anthropogenic glass. These have become much more common at the Earth's surface since the mid-twentieth century. However, the scale and extent of this new phase of mineral evolution, which represents part of the widespread changes associated with the proposed Anthropocene Epoch, remains uncharted. The International Mineralogical Association (IMA) list of officially accepted minerals explicitly excludes synthetic minerals, and no general inventory of these exists. We propose that the growing geological and societal significance of this phenomenon is now great enough for human-made minerals to be formally listed and catalogued by the IMA, perhaps in conjunction with materials science societies. Such an inventory would enable this phenomenon to be placed more effectively within the context of the 4.6 billion year history of the Earth, and would help characterize the strata of the Anthropocene.
... Hazen (2013) estimated that 420 mineral species may have been present in the Hadean Eon, whereas as many as 1500 species arose from physical and chemical events prior to 3 billion years ago. Biological processes, most notably near-surface environmental changes following the Great Oxidation Event at 2.4 to 2.2 Ga and Phanerozoic biomineralization subsequent to ~540 Ma, have led to numerous additional phases (Hazen et al. 2008(Hazen et al. , 2013a(Hazen et al. , 2013bSverjensky and Lee 2010;Dove 2010), including an estimated 70% of the ~5000 minerals approved by the International Mineralogical Association (http://rruff.info/ ima; Downs 2006). ...
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Recent studies of mineral diversity and distribution lead to the prediction of >1563 mineral species on Earth today that have yet to be described—approximately one fourth of the 6394 estimated total mineralogical diversity. The distribution of these “missing” minerals is not uniform with respect to their essential chemical elements. Of 15 geochemically diverse elements (Al, B, C, Cr, Cu, Mg, Na, Ni, P, S, Si, Ta, Te, U, and V), we predict that approximately 25% of the minerals of Al, B, C, Cr, P, Si, and Ta remain to be described—a percentage similar to that predicted for all minerals. Almost 35% of the minerals of Na are predicted to be undiscovered, a situation resulting from more than 50% of Na minerals being white, poorly crystallized, and/or water soluble, and thus easily overlooked. In contrast, we predict that fewer than 20% of the minerals of Cu, Mg, Ni, S, Te, U, and V remain to be discovered. In addition to the economic value of most of these elements, their minerals tend to be brightly colored and/or well crystallized, and thus likely to draw attention and interest. These disparities in percentages of undiscovered minerals reflect not only natural processes, but also sociological factors in the search, discovery, and description of mineral species.
... Since the rise of animals with mineral skeletons in the early Cambrian Period (0.542 billion years ago), biology (Hazen et al., 2008;Dove, 2010) saw the abrupt rise of all major skeletal minerals (the carbonates calcite, aragonite, and magnesian calcite; the calcium phosphate apatite; and the opal form of silica), and few new types of structural biominerals have appeared since then (Runnegar, 1987;Knoll, 2003;Dove et al., 2003). Calcium carbonate minerals, which represent the most extensive and diverse group of biominerals, played many roles. ...
... In BCM, the nucleation and growth of crystals are genetically controlled by microbes; a typical example is magnetite in magnetosomes produced by magnetotactic bacteria. Carbonates, phosphates, and silica in marine animals are other examples (Dove 2010). Broadly speaking, mineralization controlled by protein templates belongs to BCM as well. ...
Article
Minerals and microbes have coevolved throughout much of Earth history. They interact at the microscopic scale, but their effects are manifested macroscopically. Minerals support microbial growth by providing essential nutrients, and microbial activity alters mineral solubility and the oxidation state of certain constituent elements. Microbially mediated dissolution, precipitation, and transformation of minerals are either directly controlled by microorganisms or induced by biochemical reactions that usually take place outside the cell. All these reactions alter metal mobility, leading to the release or sequestration of heavy metals and radionuclides. These processes therefore have implications for ore formation and the bioremediation of contaminated sites.
... Although aragonite is the least stable of these minerals, and undergoes rapid recrystallization to thermodynamically more stable forms, it has been recognized as a fundamental constituent of marine depositional environments since at least the Archean (Sumner and Grotzinger 2004), and represents a primary shallow-marine depositional facies throughout the Proterozoic (Grotzinger and Read 1983; Bartley and Kah 2004;Kah and Bartley 2011). Furthermore, since the onset of enzymatic (a) (b) 28 Hazen,Downs,Jones,Kah Carbon Mineralogy & Crystal Chemistry 29 biomineralization, more than 500 million years ago, aragonite has been a primary constituent of the fossil record, forming metastable skeletons of some calcareous algae (Bathurst 1976) as well as the skeletal components of a variety of invertebrates, including a wide variety of molluscs, scleractinian corals, and some bryozoans (Cloud 1962;Rucker and Carver 1969;Knoll 2003;Dove 2010). Three other aragonite group minerals, the Sr, Ba, and Pb carbonates strontianite, witherite, and cerussite, respectively, are all found primarily in relatively low-temperature hydrothermal or supergene environments, commonly associated with sulfates and metal sulfide ores (Smith 1926;Mitchell and Pharr 1961;Mamedov 1963;Speer 1977;Dunham and Wilson 1985;Wang and Li 1991). ...
Article
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INTRODUCTION Carbon, element 6, displays remarkable chemical exibility and thus is unique in the diversity of its mineralogical roles. Carbon has the ability to bond to itself and to more than 80 other elements in a variety of bonding topologies, most commonly in 2-, 3-, and 4-coordination. With oxidation numbers ranging from −4 to +4, carbon is observed to behave as a cation, as an anion, and as a neutral species in phases with an astonishing range of crystal structures, chemical bonding, and physical and chemical properties. This versatile element concentrates in dozens of different Earth repositories, from the atmosphere and oceans to the crust, mantle, and core, including solids, liquids, and gases as both a major and trace element (Holland 1984; Berner 2004; Hazen et al. 2012). Therefore, any comprehensive survey of carbon in Earth must consider the broad range of carbon-bearing phases. The objective of this chapter is to review the mineralogy and crystal chemistry of carbon, with a focus primarily on phases in which carbon is an essential element: most notably the polymorphs of carbon, the carbides, and the carbonates. The possible role of trace carbon in nominally acarbonaceous silicates and oxides, though potentially a large and undocumented reservoir of the mantle and core (Wood 1993; Jana and Walker 1997; Freund et al. 2001; McDonough 2003; Keppler et al. 2003; Shcheka et al. 2006; Dasgupta 2013; Ni and Keppler 2013; Wood et al. 2013), is not considered here. Non-mineralogical carbon-bearing phasestreated elsewhere, including in this volume, include C-O-H-N aqueous uids (Javoy 1997; Zhang and Duan 2009; Jones et al. 2013; Manning et al. 2013); silicate melts (Dasgupta et al. 2007; Dasgupta 2013; Manning et al. 2013); carbonate melts (Cox 1980; Kramers et al. 1981; Wilson and Head 2007; Walter et al. 2008; Jones et al. 2013); a rich variety of organic molecules, including methane and higher hydrocarbons (McCollom and Simoneit 1999; Kenney et al. 2001; Kutcherov et al. 2002; Sherwood-Lollar et al. 2002; Scott et al. 2004; Helgeson et al. 2009; McCollom 2013; Sephton and Hazen 2013); and subsurface microbial life (Parkes et al. 1993; Gold 1999; Chapelle et al. 2002; D’Hondt et al. 2004; Roussel et al. 2008; Colwell and D’Hondt 2013; Schrenk et al. 2013; Meersman et al. 2013; Anderson et al. 2013). The International Mineralogical Association (IMA) recognizes more than 380 carbon- bearing minerals (http://rruff.info/ima/), including carbon polymorphs, carbides, carbonates, and a variety of minerals that incorporate organic carbon in the form of molecular crystals, organic anions, or clathrates. This chapter reviews systematically carbon mineralogy and crystal chemistry, with a focus on those phases most likely to play a role in the crust. Additional high-temperature and high-pressure carbon-bearing minerals that may play a role in the mantle and core are considered in the next chapter on deep carbon mineralogy (Oganov et al. 2013).
... (2) growth of calcite concretions in fractured and porous media (Mozley and Davis, 2005); (3) biomineralization of calcium carbonate (CaCO 3 ) shells and exoskeletons in seawater (Wasylenki et al., 2005;Morse et al., 2007;Dove, 2010): (4) biologically induced carbonate precipitation (Kandianis et al., 2008;DeJong et al., 2010): (5) formation of CaCO 3 mineral scale in oil and gas production wells (Chen et al., 2005); and (6) and mineralogical distributions and changes in geologic time (De Choudens-Sánchez and González, 2009). Over the past several decades, the vast majority of work has focused on how chemical composition affects crystal growth and dissolution kinetics of carbonates in well-mixed batch systems. ...
Article
Calcium carbonate (CaCO3) geochemical reactions exert a fundamental control on the evolution of porosity and permeability in shallow-to-deep subsurface siliciclastic and limestone rock reservoirs. As a result, these carbonate water–rock interactions play a critically important role in research on groundwater remediation, geological carbon sequestration, and hydrocarbon exploration. A study was undertaken to determine the effects of Mg2+ concentration on CaCO3 crystal morphology, precipitation rate, and porosity occlusion under flow and mixing conditions similar to those in subsurface aquifers. This was accomplished by promoting CaCO3 precipitation through the mixing of two solutions flowing parallel to each other in a microfluidic pore structure, containing uniform concentrations of dissolved Ca2+ and carbonate (CO32−), and systematic variations in the concentration of Mg2+. Raman spectroscopy indicates that all three polymorphs of CaCO3 (calcite, aragonite, and vaterite) were present under all experimental conditions. Coordinated brightfield imaging results show the morphology of calcite with increasing Mg2+ progressed from blocky and dogtooth approximately 10–80 μm in size, to anhedral spheroidal approximately 5–30 μm in size. The morphology of aragonite with increasing Mg2+ progressed from shrubs and fuzzy dumbells to spheroidal, and the size increased from approximately 5–60 μm to 20–200 μm. Recrystallization was observed in all experiments, but more so at low Mg2+, in which many small microcrystals dissolved and re-precipitated as one or a few larger calcite crystals. Analysis of brightfield images indicates calcite is the most abundant polymorph under all conditions. However, the area of pore space with aragonite increased from <5% when no Mg2+ was present to >20% at the highest Mg2+ concentration. The initial apparent precipitation rate of mineral polymorphs with no Mg2+ present was 2.5 times greater than when 40 mM Mg2+ was added, and large (20–200 μm) aragonite crystals formed primarily near to and below the center mixing zone with increasing Mg2+ concentration. Pore-scale modeling results are consistent with experiments, and indicate that all three polymorphs are thermodynamically favorable, with calcite and aragonite being the most favorable and having similar saturation ratios (SR > 100). The influence of Mg2+ on mineral precipitation rates is consistent with previous studies showing that calcite precipitation rates decrease with increasing Mg2+ concentrations. The precipitation of aragonite below the center-mixing zone is not predicted by thermodynamic SRs, but is consistent with the literature and our modeling results showing aragonite precipitation is kinetically more favorable in regions with higher Mg2+/Ca2+ ratios. Hence, both thermodynamic and kinetic constraints affect precipitation rates, the distribution of mineral polymorphs, and the corresponding extent of porosity occlusion. A tracer study demonstrated that mineral precipitation along the center-mixing zone under all experimental conditions led to substantial pore blockage. Imaging results suggest that with increasing Mg2+ concentration, slower crystal growth rates will increase the time period before pore blockage occurs, and the transition to more spherical and larger aragonite crystals below the center mixing line will increase pore occlusion and decrease mixing. Hence, understanding how Mg2+ affects calcium carbonate precipitation is very important for predicting mixing and reactive transport in subsurface reservoirs.
... ! Siliceous skeletons are spread across a wide phylogenetic distribution, produced in five out of the eight eukaryotic clades (Knoll 2003;Dove 2010). Likely costs of a siliceous skeleton include the metabolic expense of silicic acid uptake, transport, and precipitation in a low-nutrient environment, resulting in longer generation times (Brzezinski 1992). ...
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The silicoflagellates are a class of enigmatic chrysophytes characterized by netlike skeletons composed of opaline silica. Other major groups of siliceous plankton—the diatoms and radiolarians—exhibit evidence of decreasing size or silicification over the Cenozoic. We investigated trends in the silicoflagellate fossil record by constructing a species-level database of diversity and morphological metrics. This new database reveals a proliferation of silicoflagellate species with spined skeletons along with an increase in the mean number of spines per species over the Cenozoic. Although there is little change in skeleton size or silicification among species with spines, those without spines are larger than species with spines and exhibit a decrease in size toward the present. Increased grazing pressure combined with declining surface silicate availability may have shifted the costs and benefits of silicification, causing divergent responses in skeletal morphology between these different morphological lineages of silicoflagellates over time. We postulate that diminishing Cenozoic surface silicic acid availability may have predisposed large spineless silicoflagellate species to extinction, whereas increased grazing pressure may have contributed to the extinction of all remaining spineless species within the edible size range of grazers.
... After 4 billion years of evolution, nature has developed a wide variety of amazing structures and functions [26], therefore learning from nature can pave the way for designing and preparing new materials. It has been proved in most cases that the structure especially micro/nano structure of the natural biomaterials often determine its function in the actual situation27282930. ...
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Cardiovascular disease is the leading cause of deaths worldwide and the arterial reconstructive surgery remains the treatment of choice. Although large diameter vascular grafts have been widely used in clinical practices, there is an urgent need to develop a small diameter vascular graft with enhanced blood compatibility. Herein, we fabricated a small diameter vascular graft with submicron longitudinally aligned topography, which mimicked the tunica intima of the native arterial vessels and were tested in Sprague--Dawley (SD) rats. Vascular grafts with aligned and smooth topography were prepared by electrospinning and were connected to the abdominal aorta of the SD rats to evaluate their blood compatibility. Graft patency and platelet adhesion were evaluated by color Doppler ultrasound and immunofluorescence respectively. We observed a significant higher patency rate (p = 0.021) and less thrombus formation in vascular graft with aligned topography than vascular graft with smooth topography. However, no significant difference between the adhesion rates on both vascular grafts (smooth/aligned: 0.35[per mille sign]/0.12[per mille sign], p > 0.05) was observed. Moreover, both vascular grafts had few adherent activated platelets on the luminal surface. Bionic vascular graft showed enhanced blood compatibility due to the effect of surface topography. Therefore, it has considerable potential for using in clinical application.
... Since the original work of Lowenstam (1981), this process is often referred to as biomineralization. This is now a wide-open field both in environmental and evolutionary contexts (Smith 2005;Dove 2010). Despite the growing body of literature, the mechanisms of interaction are still poorly known. ...
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Several decades after the closure of the Ingurtosu mine (SW Sardinia), a variety of seasonal Zn biomineralizations occurs. In this work, waters, microbial consortia, and seasonal precipitates from the Naracauli stream were sampled to investigate chemical composition of stream waters and biominerals, and microbial strain identity. Molecular and morphological analysis revealed that activity of dominant cyanobacterium Leptolyngbya frigida results in precipitation of Zn silicate. The activity of the cyanobacterium was associated to other bacteria and many kind of diatoms, such as Halamphora subsalina and Encyonopsis microcephala, which are trapped in the process of biomineral growth. In this work, the precipitation process is shown to be the result of many different parameters such as hydrologic regime, microbial community adaptation, and biological mediation. It results in a decrease of dissolved Zn in the stream water, and is a potential tool for Zn pollution abatement.
... One of the most important processes controlling Mg biogeochemical cycling in continental waters is carbonate biomineralization (Lowenstum and Weiner 1989;Dove 2010). Cyanobacteria-induced mineralization has occurred in lacustrine environments since the Precambrian (Kempe and Kazmierczak 1990;Knoll et al. 1993;Brady et al. 2009;Planavsky et al. 2009;Raven and Giordano 2009;Riding 2000;Ries 2010). ...
Article
This study assesses the potential use of Mg isotopes to trace Mg carbonate precipitation in natural waters. Salda Lake (SW Turkey) was chosen for this study because it is one of the few modern environments where hydrous Mg carbonates are the dominant precipitating minerals. Stromatolites, consisting mainly of hydromagnesite, are abundant in this lake. The Mg isotope composition of incoming streams, groundwaters, lake waters, stromatolites, and hydromagnesite-rich sediments were measured. Because Salda Lake is located in a closed basin, mass balance requires that the Mg isotopic offset between Lake Salda water and precipitated hydromagnesite be comparable to the corresponding offset between Salda Lake and its water inputs. This is consistent with observations; a δ26Mg offset of 0.8–1.4 ‰ is observed between Salda Lake water and it is the incoming streams and groundwaters, and precipitated hydromagnesite has a δ26Mg 0.9–1.1 ‰ more negative than its corresponding fluid phase. This isotopic offset also matches closely that measured in the laboratory during both biotic and abiotic hydrous Mg carbonate precipitation by cyanobacteria (Mavromatis, V., Pearce, C., Shirokova, L. S., Bundeleva, I. A., Pokrovsky, O. S., Benezeth, P. and Oelkers, E.H.: Magnesium isotope fractionation during inorganic and cyanobacteria-induced hydrous magnesium carbonate precipitation, Geochim. Cosmochim. Acta, 2012a. 76, 161–174). Batch reactor experiments performed in the presence of Salda Lake cyanobacteria and stromatolites resulted in the precipitation of dypingite (Mg5(CO3)4(OH)2·5(H2O)) and hydromagnesite (Mg5(CO3)4(OH)2·4H2O) with morphological features similar to those of natural samples. Concurrent abiotic control experiments did not exhibit carbonate precipitation demonstrating the critical role of cyanobacteria in the precipitation process.
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Biominerals formed by animals are most frequently calcium carbonate or phosphate polycrystalline materials with complex hierarchical structures. This article will focus on the 10-nm–10-µm scale, termed “mesoscale,” at which the “mesostructure” differs greatly across biominerals, is relevant to their mechanical properties, and reveals formation mechanisms in sea urchin teeth, mollusk shell prisms and nacre, human enamel, and coral skeletons. This article will conclude by focusing on important unanswered questions to inspire future research. Graphical abstract
Article
Magnesium (Mg) is abundant on Earth's surface aquatic environments and plays an important role during the precipitation of biogenic CaCO3 minerals. Moreover, Mg isotopes are increasingly used to study a number of bio-induced mineralization processes of calcite. In this study, Mg isotope signatures during calcite and aragonite precipitation in the presence of Curvibacter sp. HJ-1 and of their extracellular polymeric substances (EPS) were investigated and the evolution of mineralogical and liquid composition were tracked over time. The results showed that light Mg isotopes were preferentially incorporated into the precipitated solids in all the experiments with and without bacteria. Significant Mg isotope fractionation was associated with the transformation of amorphous calcium carbonate (ACC) to crystal carbonate (Δ²⁶Mgcrystals-ACC = −0.9‰ and −0.7‰ in biotic and EPS experiments, respectively), and obvious Mg isotope fractionation was noted between solids and liquid (Δ²⁶Mgsolid-liquid achieved −2.2‰ and −2.0‰ in biotic and EPS experiments, respectively). Besides, δ²⁶Mg values were significantly correlated with pH, Mg content in liquid and solid, bacterial density and presence of EPS in biotic experiments. These findings indicated that strain HJ-1 had an effect on Mg isotope fractionation during calcite and aragonite precipitation. The difference in Mg isotope fractionation may be a new tool for understanding the biologically mediated effects on Mg-bearing carbonate precipitation, and serves as a useful alternative for aqueous Mg isotope, which is vital for reconstructing past environmental changes.
Chapter
Distinction is made between biominerals and true minerals or minerals strictu sensu (s.s.), the first formed by the action of biological or cellular activity, the second formed in the natural environment without human intervention. Biominerals are products of a process called biomineralization and are classified into two categories: bio-essential biominerals forming bones and teeth and pathological biominerals forming the so-called calculi or stones in the kidney, vesica, bladder, gallbladder and in joints, the first providing positive physiological effects, the second providing negative physiological effects and health disorders. This chapter describes the great variety of biominerals, their formation, physical and chemical constitution, and function. The so-called ectopic biomineralization is dealt with too. In particular the chemistry and the causes of pathological biominerals formation are enhanced.
Chapter
The historical evolution of the use of minerals by humans for cosmetic and therapeutic purposes is most probably as old as the human species itself, naturally first applied on an empirical basis, and later moved to a scientific basis initiated with the dawn of scientific revolution, in the Renaissance. Such evolution is classified in this monograph into three periods: the classical antiquity involving ancient civilizations, Mesopotamian, Chinese, Egyptian, Greek, and Roman; the Middle Ages and Renaissance; and the modern and contemporaneous ages. In these periods, the interest for certain minerals as healing natural materials is reported and discussed. The “medicinal terras” of the Greek volcanic islands Lemnos, Chios, Samos, Milos, and Kimolos were particularly famed, as was the case of the “Lemnian terra,” which became known as “terra sigillata” or “terra sealed” supposed to possess supernatural healing properties. On the other hand, certain arsenic-, lead-, and mercury-bearing minerals were soon identified by their poison and lethal properties. From the Renaissance onwards, the First and Second Scientific Revolutions and their particular outcomes in pharmacy and medicine have provided the explanations and justifications for both benefits and risks of minerals/human health interactions.
Chapter
Minerals are naturally occurring, macroscopically homogeneous components of the Earth and other celestial bodies (Moon, meteorites, terrestrial planet of our and other solar systems) with a definite but not necessarily fixed chemical composition.
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The know-how in carbonate systems requires digging into the basic concepts to increase interpretative accuracy and succeed in predictions. The more in-depth the knowledge about how fundamental processes work in the construction of the sedimentary record, the more efficient the resolution of problems. However, there is a tremendous asymmetry in the knowledge of the processes operating in siliciclastic systems and the processes running in carbonate systems. Whereas siliciclastics mostly require understanding the physical laws, carbonate systems are derived from biological systems and need additional knowledge in the evolution of life first, second in the biotic responses to environmental changes and third in how environmental conditions have been changing on Earth. The implicit concatenation of these requirements, and the increased uncertainties when considering carbonates generated from older extinct biotas, has delayed the conceptual understanding of the development of carbonate systems. However, recent advances in ecology and palaeoecology, increase in palaeoenvironmental proxies and the progress in molecular evolution and the palaeobiological revolution are providing the basis to face the study of carbonate systems much more efficiently and diminishing the risk of unrealistic predictions. In the first introductory section, the knowledge space in Sedimentary Geology is analyzed, placing the emphasis in the transfers of energy and matter existing in siliciclastic and carbonate systems, leading to frame the concept of carbonate factories: the sediment source. Most carbonate rocks are of biological origin and photosynthesis is the primary step in organic production, at the base of the food web. Autotrophic processes in aquatic systems require inorganic carbon (IC), protons, nutrients and energy. When the proton donor is water, the subproduct is oxygen, but taking the proton from bicarbonate the subproduct is carbonate. ‘Food and feeding/follow the food’ section focuses on the analyses of the carbonate precipitation mechanisms and of the interrelated food web: the grazer chain and the microbial, picoplankton and sponge loops. Light for energy and the hydrodynamic regime as the carrier for dissolved nutrients and organic carbon (food) are the most basic requirements for organic and hence carbonate production. ‘Boundary layers’ section provides insights into the impact of the boundary layers conditions: light and energy. One sentence summarizes ‘Feed and food: feasting at the pycnoclines’ section. Feeding and feasting are behind the organic production and carbonate precipitation. Next, in ‘Carbonate production modes’ section, come the analyses of the different carbonate precipitation modes resulting from the complex interaction between ambient water chemistry and life. ‘Carbonate production systems through Earth’s history’ section examines the products of these complex interactions from the Archean to the Neogene. ‘Platform types’ section establishes the main typologies of carbonate platforms through the analyses of a series of case studies. The chapter ends with a corollary discussing (1) the interaction between factories (promotion vs suffocation), (2) the types of responses of carbonate platforms to external changes (linear vs nonlinear), (3) the uses and misuses of skeletal sediment associations and (4) the obstinate misuse of the sequence stratigraphic concepts in carbonate systems.
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In this study, the concentrations of 12 metals: Ca, Na, Sr, Mg, Ba, Mn, Cu, Pb, V, Y, U and Cd in shells of bivalve molluscs (aragonitic: Cerastoderma glaucum, Mya arenaria and Limecola balthica and bimineralic: Mytilus trossulus) and arthropods (calcitic: Amphibalanus improvisus) were obtained. The main goal was to determine the incorporation patterns of shells built with different calcium carbonate polymorphs. The role of potential biological control on the shell chemistry was assessed by comparing the concentrations of trace elements between younger and older individuals (different size classes). The potential impact of environmental factors on the observed elemental concentrations in the studied shells is discussed. Specimens were collected from brackish waters of the Baltic Sea (the Gulf of Gdansk). For every species, 40 individuals (ten in each size class) were selected. Pre-cleaned shells were analysed by ICP-OES and ICP-MS to determine the concentrations of metals. The distributions of elements both differ between species and exhibit high intraspecific variability. Calcitic shells preferentially incorporated Mg > Sr > Na, aragonitic shells incorporated Na > Sr > Mg, and bimineralic shells accumulated Na approximately two times more intensively, than Mg and Sr which remained at similar levels. Among all species, the calcitic shells of A. improvisus most effectively concentrated the majority of the studied elements, especially Mg > Mn > Ba, which was contrary to the shells of aragonitic molluscs that contained the lowest levels of trace elements. The size-dependent distributions of elements in shells did not exhibit a consistent pattern. The highest significant differences were found for the bimineralic shells of M. trossulus, while the smallest were found for aragonitic shells; if any variability occurred, it was observed in heavy metals (Pb, Cd). Our results indicate that elemental variability, especially that of Mg and Sr, is dominated by the properties of the crystal lattice. The inconsistent variability of trace element concentrations between species and within single populations supports the important role of species-specific biological control of the biomineralization process and indicates that environmental factors have a significant influence on the incorporation of trace elements into the shells.
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Minerale sind chemisch einheitliche, natürliche Bestandteile der Erde und anderer Himmelskörper (Mond, Meteoriten, erdähnliche Planeten unseres und anderer Sonnensysteme). Von wenigen Ausnahmen abgesehen, sind Minerale anorganisch, fest und kristallisiert (Abb. 1.1, 2.1).
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Microbially-induced mineralization is considered as one of the main natural processes controlling CO2 levels in the atmosphere and a major structural and ecological player, in the modern and in the past ecosystems. In this study are presented the data of laboratory experimental work on CaCO3 precipitation with pure cultures of two anoxygenic phototrophs bacteria (APB): haloalcaliphilic Rhodovulum steppens A-20s and neutrophilic halophilic Rhodovulum sp. S-17-65; and cyanobacteria Gloeocapsa sp.. These bacteria represent two important groups of photosynthetic organisms in the past and at present time. APB is the oldest microorganism which could be dominant during the anoxygenic period of Earth's life (approximately 4 billon years ago) whereas the origin of oxygen evolving microorganisms (cyanobacteria) is placed at about 3.5 billion years ago as based on oxidation records of the Earth's crust. In modern ecosystems, cyanobacteria are the dominant primary producers. Nonetheless, the potential of APB are abundant in the modern microbial mats and stromatolites and thus may represent a considerable fraction of the standing biomass. However, biomineralization induce by these bacteria has not been thoroughly studied up to now. In this context, the aim of this thesis is to characterize the process of biological CaCO3 precipitation and to assess the existence of metabolic processes protecting studied bacteria against carbonate mineralization on their surfaces. For this, kinetic experiments, SEM and TEM imaging, EDX and XRD analyses, zeta-potential measurements and Ca adsorption into bacterial surface were carried out. The result of this study demonstrates the participation of studied bacteria in CaCO3 precipitation. Zeta-potential measurements suggest the existence of a cells protection mechanism for studied APB, based on the metabolic maintenance of a positive surface charge at alkaline pH, preserving active bacteria against Ca2+ adsorption and subsequent carbonate precipitation on their surfaces. The existence of the same mechanism for Gloeocapsa sp. was not confirmed. Overall, the results of this study show two different mechanisms of CaCO3-nucleation: an unspecific supersaturation by APB and a specific nucleation at the cell wall by cyanobacteria Gloeocapsa sp..
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The formation of various authigenic minerals, primarily dolomite, has been described in the lacustrine and fluvio-lacustrine Miocene sediments of the Madrid and Duero Basins. The authors of the present study have found indirect evidence of sepiolite formation by biogenically related mechanisms in the dolomite–sepiolite materials that were formed in shallow lacustrine environments from the intermediate unit of the Miocene in the north-eastern area of the Madrid Basin. The aim of this study was to determine similarities between sepiolite or sepiolite–dolomite aggregation morphologies at the micro-nanometre scale and to distinguish biologically originated microstructures.The proposed organomineralization process occurs in two steps related mainly to a passive biologically influenced process. In a first step, bacterial or microalgae extracellular polymeric substances (EPS) adsorbs Mg selectively from the solution and is attached to negatively charged sites, thereby simultaneously acting as a silica precipitation support. In the second step, the reaction of Mg with the biogenic silica during the degradation of EPS may lead to the nucleation of sepiolite crystals using the fibrous organic support.There are still many remaining issues and experimental studies required to document the biologically influenced process of sepiolite formation. The environmental cycling changes in ephemeral lakes that result in the periodicity of acidic and alkaline, oxic and anoxic, and wet–dry conditions may contribute to activate and accumulate the mineralization. Complementarily, the understanding of the role of natural biopolymers in the organomineralization processes becomes necessary for the determination of the biological origin of authigenic minerals precipitating in surface environments.
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Many animal phyla have the physiological ability to produce biomineralized skeletons with functional roles that have been shaped by natural selection for more than 500 million years. Among these are bryozoans, a moderately diverse phylum of aquatic invertebrates with a rich fossil record and importance today as bioconstructors in some shallow-water marine habitats. Biomineralizational patterns and, especially, processes are poorly understood in bryozoans but are conventionally believed to be similar to those of the related lophotrochozoan phyla Brachiopoda and Mollusca. However, bryozoan skeletons are more intricate than those of these two phyla. Calcareous skeletons have been acquired independently in two bryozoan clades – Stenolaemata in the Ordovician and Cheilostomata in the Jurassic – providing an evolutionary replicate. This review aims to highlight the importance of biomineralization in bryozoans and focuses on their skeletal ultrastructures, mineralogy and chemistry, the roles of organic components, the evolutionary history of bimineralization in bryozoans with respect to changes in seawater chemistry, and the impact of contemporary global changes, especially ocean acidification, on bryozoan skeletons. Bryozoan skeletons are constructed from three different wall types (exterior, interior and compound) differing in the presence/absence and location of organic cuticular layers. Skeletal ultrastructures can be classified into wall-parallel (i.e. laminated) and wall-perpendicular (i.e. prismatic) fabrics, the latter apparently found in only one of the two biomineralizing clades (Cheilostomata), which is also the only clade to biomineralize aragonite. A plethora of ultrastructural fabrics can be recognized and most occur in combination with other fabrics to constitute a fabric suite. The proportion of aragonitic and bimineralic bryozoans, as well as the Mg content of bryozoan skeletons, show a latitudinal increase into the warmer waters of the tropics. Responses of bryozoan mineralogy and skeletal thickness to oscillations between calcite and aragonite seas through geological time are equivocal. Field and laboratory studies of living bryozoans have shown that predicted future changes in pH (ocean acidification) combined with global warming are likely to have detrimental effects on calcification, growth rate and production of polymorphic zooids for defence and reproduction, although some species exhibit reasonable levels of resilience. Some key questions about bryozoan biomineralization that need to be addressed are identified.
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Calix[4]arenes functionalised at the upper rim with acidic amino acid residues are found to have a significant impact on the crystal growth of model mineral systems, calcium carbonate and barium sulphate. The aspartic acid derivative is found to be most efficacious, matching or exceeding the impact of commercial phosphonate-based scale inhibitors. In some cases, the modified morphologies are found to be similar to those induced by proteins isolated from biomineralised systems.
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In the last decade, extensive studies have been conducted to understand the chemical and biological processes of nanoparticles and their effects on ecological functions and human health. This review focuses on the nature and properties of natural nanoparticles (NNPs) and their influence on the physical, chemical, and biological processes in plant-soil-water systems. The NNPs are involved directly or indirectly in numerous soil processes such as aggregate formation, nutrient retention, microbial activities, and water purification and pollution mitigation and thus affect soil/environment quality and human health. This paper is intended to provide a brief review of recent progress in related fields.
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The present review focuses on some specific aspects of biomineralization with regard to the evolution of the first focused visioning systems in trilobites, the formation of molluscan shell architecture, dental enamel and its biomechanical properties and the structure of the calcified amniote egg, both fossil and recent. As an interdisciplinary field, biomineralization deals with the formation, structure and mechanical strength of mineralized skeletonized tissue secreted by organisms. Mineral matter formed in this way occurs in all three domains of life and consists of several mineral varieties, of which carbonates, phosphates and opaline silica are the most common. Animals and plants need mechanical support to counteract gravitational forces on land and hydrostatic pressure in the deep ocean, which is provided by a skeletonized framework. Skeleton architecture mainly consists of basic elements represented by small usually micrometer- to nanometer-sized crystallites of calcite and aragonite for carbonate systems and apatite crystallites for phosphatic ones, and then these building blocks develop into structured more complex frameworks. As selective pressures work towards optimizing stress and response, the orientation, morphology and structural arrangement of the crystallites indicates the distribution of the stress field of the biomineralized tissue. Large animals such as the dinosaurs have to deal with large gravitational forces, but in much smaller skeletonized organism such as the coccoliths, a few micrometer in diameter made up of even smaller individual crystallites, van der Waals forces play an increasingly important role and are at present poorly understood. Skeleton formation is dependent upon many factors including ambient water chemistry, temperature and environment. Ocean chemistry has played a vital role in the origins of skeletonization, 500 to 600 million years (ma) ago with the dominance of calcium carbonate as the principal skeleton-forming tissue and with phosphates and silica as important but secondary materials. The preservation of calcareous skeletons in deep time has resulted in providing interesting information: for example, the number of days in the Devonian year has been established on the basis of well-preserved lunar (annual) cycles, and isotope chemistry has led to an elaborate protocol for using O18/O16 stable isotopes for palaeotemperature measurements in the geological past. Stable isotopes of dental apatite have helped to establish ecological shifts (terrestrial to wholly marine) during the evolution of the Cetacea. Biomineralization as a field of specialization is still searching for its own independent identity, but gradually, its importance is being realized as a model for engineering applications especially at the nanometer scale.
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The fractionation of Mg isotopes was determined during the cyanobacterial mediated precipitation of hydrous magnesium carbonate precipitation in both natural environments and in the laboratory. Natural samples were obtained from Lake Salda (SE Turkey), one of the few modern environments on the Earth's surface where hydrous Mg-carbonates are the dominant precipitating minerals. This precipitation was associated with cyanobacterial stromatolites which were abundant in this aquatic ecosystem. Mg isotope analyses were performed on samples of incoming streams, groundwaters, lake waters, stromatolites, and hydromagnesite-rich sediments. Laboratory Mg carbonate precipitation experiments were conducted in the presence of purified Synechococcus sp cyanobacteria that were isolated from the lake water and stromatolites. The hydrous magnesium carbonates nesquehonite (MgCO3·3H2O) and dypingite (Mg5(CO3)4(OH)25(H2O)) were precipitated in these batch reactor experiments from aqueous solutions containing either synthetic NaHCO3/MgCl2 mixtures or natural Lake Salda water, in the presence and absence of live photosynthesizing Synechococcus sp. Bulk precipitation rates were not to affected by the presence of bacteria when air was bubbled through the system. In the stirred non-bubbled reactors, conditions similar to natural settings, bacterial photosynthesis provoked nesquehonite precipitation, whilst no precipitation occurred in bacteria-free systems in the absence of air bubbling, despite the fluids achieving a similar or higher degree of supersaturation. The extent of Mg isotope fractionation (Delta26Mgsolid-solution) between the mineral and solution in the abiotic experiments was found to be identical, within uncertainty, to that measured in cyanobacteria-bearing experiments, and ranges from -1.4 to -0.7 0/00. This similarity refutes the use of Mg isotopes to validate microbial mediated precipitation of hydrous Mg carbonates.
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Mineral evolution, which frames mineralogy in a historical context, is based on the premise that the geosphere and biosphere have coevolved through a sequence of deterministic and stochastic events. Three eras of mineral evolution—planetary accretion, crust and mantle reworking, and biologically mediated mineralogy—each saw dramatic changes in the diversity and distribution of Earth's near-surface minerals. An important implication of this model is that different terrestrial planets and moons achieve different stages of mineral evolution, depending on the geological, petrological, and biological evolution of the body.
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The primordial earth surface exposed minerals comprised mainly of carbonates, silicates and smaller amounts of phosphates. Weathering eventually led to the dissolution of the surface rock and the leaching of their components into the rivers, lakes and oceans. There, complex chemistry depending upon the temperature, pH, pressure, and atmospheric carbon dioxide content led to the reprecipitation of the dissolved minerals into new forms as part of the sedimentary rock. The minerals themselves could be transformed by passive diagenesis to further structures. When primitive organisms emerged, they added a very significant component to the processing of the dissolved mineral constituents in the marine environment, where both prokaryotic and eukaryotic organisms have the ability to produce mineralized skeletal elements and mineralized fecal pellets that also accumulate in the marine sediments. The increasing diversity of plant and animal life has continually accelerated the dynamic relationship between the composition of the earths crust and the living world. The resulting minerals of biogenic origin comprise a surprisingly large portion of the earths crust, and represent a huge reservoir of sequestered carbonate, silicate and phosphate ions. The majority of the carbonates appear as calcite or aragonite, produced principally by plankton, invertebrates and so on, while the phosphates, as carbonated hydroxyapatite, are the products of vertebrates as well as the weathering of igneous rock. This chapter is focused on the mechanisms of formation of the vertebrate mineralized structures; bone, tooth enamel, tooth dentin and otoliths. Although other Chapters deal explicitly with the invertebrate and bacterial systems, we need to consider if there are any general considerations that apply to all biogenic mineralization systems. We shall begin from that perspective and inquire as to the way by which living organisms can organize their mineral phases into such complex and specific structures. The term “Biomineralization” implies that a mineral …
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Calcareous skeletons evolved as part of the greater Ediacaran–Cambrian diversification of marine animals. Skeletons did not become permanent, globally important sources of carbonate sediment, however, until the Ordovician radiation. Representative carbonate facies in a Series 3 (510–501 Ma) Cambrian to Tremadocian succession from western Newfoundland, Canada, and Ordovician successions from the Ibex area, Utah, USA, show that, on average, Cambrian and Tremadocian carbonates contain much less skeletal material than do post-Tremadocian sediments. Petrographic point counts of skeletal abundance within facies and proportional facies abundance in measured sections suggest that later Cambrian successions contain on average <5% skeletal material by volume, whereas the skeletal content of post-Tremadocian Ordovician sections is closer to 15%. A compilation of carbonate stratigraphic sections from across Laurentia confirms that post-Tremadocian increase in skeletal content is a general pattern and not unique to the two basins studied. The long interval (40 myr) between the initial Cambrian appearance of carbonate skeletons and the subsequent Ordovician diversification of heavily skeletonized organisms provides an important perspective on the Ordovician radiation. Geochemical data increasingly support the hypothesis that later Cambrian oceans were warm and, in subsurface water masses, commonly dysoxic to anoxic. We suggest that surface waters in such oceans would have been characterized by relatively low saturation states for calcite and aragonite. Mid-Ordovician cooling would have raised oxygen concentrations in subsurface water masses, establishing more highly oversaturated surface waters. If correct, these links could provide a proximal trigger for the renewed radiation of heavily skeletonized invertebrates and algae. Organismic and Evolutionary Biology Accepted Manuscript
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The sudden appearance of calcified skeletons among many different invertebrate taxa at the Precambrian-Cambrian transition may have required minor reorganization of preexisting secretory functions. In particular, features of the skeletal organic matrix responsible for regulating crystal growth by inhibition may be derived from mucous epithelial excretions. The latter would have prevented spontaneous calcium carbonate overcrusting of soft tissues exposed to the highly supersaturated Late Proterozoic ocean [Knoll, A. H., Fairchild, I. J. & Swett, K. (1993) Palaios 8, 512-525], a putative function for which we propose the term "anticalcification." We tested this hypothesis by comparing the serological properties of skeletal water-soluble matrices and mucous excretions of three invertebrates--the scleractinian coral Galaxea fascicularis and the bivalve molluscs Mytilus edulis and Mercenaria mercenaria. Crossreactivities recorded between muci and skeletal water-soluble matrices suggest that these different secretory products have a high degree of homology. Furthermore, freshly extracted muci of Mytilus were found to inhibit calcium carbonate precipitation in solution.
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The structures of animal skeletons converge repeatedly on a limited number of architectural designs that can be constructed by growing organisms and that are functionally viable, although often not optimal. Properties of materials, construction rules that determine patterns of development, and physical constraints exerted by the requirements of function suggest that organic structure must necessarily approach these recurrent elements of design. A set of potential designs for the elements of animal skeletons is derived in terms of geometric and construction rules and the properties of materials. Skeletons of actual living and extinct organisms are matched with the possibilities defined within this theoretical morphospace. This provides a metric of skeletal complexity and of the extent to which var-ious groups of animals have been able to exploit the range of possibilities of organic structure. These analyses show that the most evolutionarily advanced animals within a given phylum do not have the most complex skeletons; that arthropods are less morphologically diverse than vertebrates and molluscs: that the physical constraints of life on land and in the air substantially limit the variety of skeletal structures suitable for life in these environments; and that overall the range of possible sketelal designs has been very fully exploited by living and extinct organisms. These results strongly support the hypothesis that the essential elements of organic design are inherent in the material properties of the universe. The organizational properties of animal skeletons suggest that their design elements are fixed point attractors, structures that we characterize as topological attractors that evolution cannot avoid.
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Current information on the conodonts Clydagnathus windsorensis (Globensky) and Promissum pulchrum Kovács–Endrödy, together with the latest interpretations of conodont hard tissues, are reviewed and it is concluded that sufficient evidence exists to justify interpretation of the conodonts on a chordate model. A new phylogenetic analysis is undertaken, consisting of 17 chordate taxa and 103 morphological, physiological and biochemical characters; conodonts are included as a primary taxon. Various experiments with character coding, taxon deletion and the use of constraint trees are carried out. We conclude that conodonts are cladistically more derived than either hagfishes or lampreys because they possess a mineralised dermal skeleton and that they are the most plesiomorphic member of the total group Gnathostomata. We discuss the evolution of the nervous and sensory systems and the skeleton in the context of our optimal phylogenetic tree. There appears to be no simple evolution of free to canal-enclosed neuromasts; organised neuromasts within canals appear to have arisen at least three times from free neuromasts or neuromasts arranged within grooves. The mineralised vertebrate skeleton first appeared as odontodes of dentine or dentine plus enamel in the paraconodont/euconodont feeding apparatus. Bone appeared later, co-ordinate with the development of a dermal skeleton, and it appears to have been primitively acellular. Atubular dentine is more primitive than tubular dentine. However, the subsequent distribution of the different types of dentine (e.g. mesodentine, orthodentine), suggests that these tissue types are homoplastic. The topology of relationships and known stratigraphic ranges of taxa in our phylogeny predict the existence of myxinoids and petromyzontids in the Cambrian.
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The fascinating shapes and hierarchical designs of biomineralized structures have long been an inspiration to materials scientists because of the potential they suggest for biomolecular control over synthesis of crystalline materials. One prevailing view is that mineral-associated macromolecules are responsible for initiating and stabilizing non-equilibrium crystal polymorphs and morphologies through interactions between anionic moieties and cations in solution or at mineral surfaces. Indeed, numerous studies have demonstrated that bio-organic additives can dramatically alter crystal shapes and growth-rates in vitro. However, previous molecular-scale studies revealing mechanisms of growth modification focused on small molecules such as amino acids or peptides and always observed growth inhibition. In contrast, studies using full proteins were non-quantitative and underlying sources of growth modification were ill-defined. Here we investigate interactions between proteins isolated from abalone shell nacre and growing surfaces of calcite. We find that these proteins significantly accelerate the molecular-scale kinetics and, though much larger than atomic steps, alter growth morphology through step-specific interactions that lower their free energies. We propose that these proteins act as surfactants to promote ion attachment at calcite surfaces.
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Siliceous plankton have been an important component of the oceanic silica cycle since the evolution of Radiolaria during late Precambrian or early Paleozoic time. Diatoms did not enter the cycle until Jurassic time, but now account for as much as 90 percent of the suspended silica in the oceans. It is postulated that the tremendous evolutionary success of the diatoms is responsible for evolutionary trends observable in the Cenozoic fossil record of the Radiolaria. Such trends include decrease in test weight, as well as structural changes such as increased pore size, decreased bar width, reduction or loss of test processes, and more regular alignment of pores--all changes that result in less silica uptake per test. Natural selection, mediated by the role of the diatoms in the silica cycle, apparently favors radiolarian phenotypes which use less silica in test construction. Organismic and Evolutionary Biology
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Geobiologists seek to understand the role of organisms in the Earth system. By extension, one can ask how evolutionary innovations and, more generally, the population genetic processes that mediate evolution have influenced the Earth’s surface through time. The example of oxygenic photosynthesis and the redox history of atmospheres and oceans illustrates the complex relationship between evolution and environmental change. Biological innovations determine the dimensions of biological participation in the Earth system, but by themselves they seldom generate lasting environmental change. More commonly, environments change when physical drivers exceed the limited environmental buffering capacity conferred by population genetics and nutritional codependence. Environmental change, in turn, feeds back on biology, creating new opportunities for evolutionary innovation. Organismic and Evolutionary Biology
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An in situ, atomic force microscopy- (AFM-)-based experimental approach is developed to directly measure the kinetics of silica nucleation on model biosubstrates under chemical conditions that mimic natural biosilica deposition environments. Relative contributions of thermodynamic and kinetic drivers to surface nucleation are quantified by use of amine-, carboxyl-, and hybrid NH(3)(+)/COO(-)-terminated surfaces as surrogates for charged and ionizable groups on silica-mineralizing organic matrices. The data show that amine-terminated surfaces do not promote silica nucleation, whereas carboxyl and hybrid NH(3)(+)/COO(-) substrates are active for silica deposition. The rate of silica nucleation is approximately 18x faster on the hybrid substrates than on carboxylated surfaces, but the free energy barriers to cluster formation are similar on both surface types. These findings suggest that surface nucleation rates are more sensitive to kinetic drivers than previously believed and that cooperative interactions between oppositely charged surface species play important roles in directing the onset of silica nucleation. Further experiments to test the importance of these cooperative interactions with patterned NH(3)(+)/COO(-) substrates, and aminated surfaces with solution-borne anionic species, confirm that silica nucleation is most rapid when oppositely charged species are proximal. By documenting the synergy that occurs between surface groups during silica formation, these findings demonstrate a new type of emergent behavior underlying the ability of self-assembled molecular templates to direct mineral formation.
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This paper presents a general overview of calcification and involves aspects of the chemical, physical, and biological nature of mineral crystals in invertebrate and vertebrate tissues, with selected examples of the latter. Two broad areas are described: mineral structure and composition. Mineral formation is detailed in an incidental fashion. Both classical research and recent data appropriate to mineralization studies are noted in order to convey basic principles, as well as the sense and direction of current investigations on the mineral phases of calcified tissues. In this context, novel analytical and imaging techniques from a number of different laboratories lately have helped characterize crystal size, shape, and composition; mineral association with respect to collagen; atomic lattice structure of crystal surfaces; interrelationships between non-collagenous matrix components and mineral; and stereochemical organization of putative matrix nucleation sites. Together, this work has provided a more complete understanding of the mineral-matrix atomic, molecular, and macromolecular interactions that underlie the general mechanism of calcification in biological tissues.
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Photosensitivity in most echinoderms has been attributed to 'diffuse' dermal receptors. Here we report that certain single calcite crystals used by brittlestars for skeletal construction are also a component of specialized photosensory organs, conceivably with the function of a compound eye. The analysis of arm ossicles in Ophiocoma showed that in light-sensitive species, the periphery of the labyrinthic calcitic skeleton extends into a regular array of spherical microstructures that have a characteristic double-lens design. These structures are absent in light-indifferent species. Photolithographic experiments in which a photoresist film was illuminated through the lens array showed selective exposure of the photoresist under the lens centres. These results provide experimental evidence that the microlenses are optical elements that guide and focus the light inside the tissue. The estimated focal distance (4-7 micrometer below the lenses) coincides with the location of nerve bundles-the presumed primary photoreceptors. The lens array is designed to minimize spherical aberration and birefringence and to detect light from a particular direction. The optical performance is further optimized by phototropic chromatophores that regulate the dose of illumination reaching the receptors. These structures represent an example of a multifunctional biomaterial that fulfills both mechanical and optical functions.
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Tidal flat and lagoonal dolostones of the Neoproterozoic Draken Formation, Spitsbergen, exhibit excellent preservation of carbonate fabrics, including heavily calcified microfossils. The crust-forming cyanobacterium Polybessurus is preserved locally by carbonate precipitated on and within sheaths in mildly evaporitic upper intertidal to supratidal environments. In contrast, calcified filaments in columnar stromatolites reflect subtidal precipitation. Filament molds in dolomicrites independently document extremely early lithification. The presence of heavily calcified cyanobacteria in Draken and other Proterozoic carbonates constrains potential explanations for the widespread appearance of calcified microorganisms near the Proterozoic-Cambrian boundary. We propose that the rarity of Proterozoic examples principally reflects the abundance and wide distribution of carbonate crystals precipitated on the sea floor or in the water column. Cyanobacterial sheaths would have competed effectively as sites for carbonate nucleation and growth only where calcitic and/or aragonitic nuclei were absent. In this view, the Proterozoic-Cambrian expansion of calcified microfossils primarily reflects the emergence of skeletons as principal agents of carbonate deposition.
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The composition of biologic molecules isolated from biominerals suggests that control of mineral growth is linked to biochemical features. Here, we define a systematic relationship between the ability of biomolecules in solution to promote the growth of calcite (CaCO3) and their net negative molecular charge and hydrophilicity. The degree of enhancement depends on peptide composition, but not on peptide sequence. Data analysis shows that this rate enhancement arises from an increase in the kinetic coefficient. We interpret the mechanism of growth enhancement to be a catalytic process whereby biomolecules reduce the magnitude of the diffusive barrier, Ek, by perturbations that displace water molecules. The result is a decrease in the energy barrier for attachment of solutes to the solid phase. This previously unrecognized relationship also rationalizes recently reported data showing acceleration of calcite growth rates over rates measured in the pure system by nanomolar levels of abalone nacre proteins. These findings show that the growth-modifying properties of small model peptides may be scaled up to analyze mineralization processes that are mediated by more complex proteins. We suggest that enhancement of calcite growth may now be estimated a priori from the composition of peptide sequences and the calculated values of hydrophilicity and net molecular charge. This insight may contribute to an improved understanding of diverse systems of biomineralization and design of new synthetic growth modulators.