Isabelle Domart-Coulon

Muséum National d'Histoire Naturelle · Dpt. Adaptations du Vivant (AViv), MCAM laboratory UMR7245 CNRS-MNHN

Ostreobium sp. (Bryopsidales, Ulvophyceae) is a major microboring alga involved in tropical reef dissolution, with a proposed symbiotic lifestyle in living corals. However, its diversity and colonization dynamics in host's early life stages remained unknown. Here, we mapped microborer distribution and abundance in skeletons of the branching coral P...

Background: Global warming has triggered an increase in the prevalence and severity of coral disease, yet little is known about coral/pathogen interactions in the early stages of infection. The point of entry of the pathogen and the route that they take once inside the polyp is currently unknown, as is the coral's capacity to respond to infection....

Background Tropical coral reefs cover ca. 0.1% of the Earth’s surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. However, they are currently threatened by both local (e.g. nutrient enrichment and chemical pollution of coastal reefs, arising from poor land management, agricultur...

The filamentous chlorophyte Ostreobium sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic versus free-living growth forms). Here...

The stem cells discipline represents one of the most dynamic areas in biology and biomedicine. The vast majority of research on stem cells is being conducted in vertebrate models. Currently, over 98% of all cell lines are of mammalian origin, which represent only 0.4% of the extant identified metazoan evolution. In particular, aquatic invertebrates...

Planktonic larvae of many marine invertebrates settle on a suitable substrate and metamorphose into bottom-dwelling adults. Larval settlement is of considerable interest both for ecologists and for evolutionary biologists, who have proposed that anterior sensory systems for substrate selection provided the basis for animal brains. Nevertheless the...

Microscopic filaments of the siphonous green algae Ostreobium (Ulvophyceae, Bryopsidales) colonize and dissolve the calcium carbonate skeletons of coral colonies in reefs of contrasted salinities. Here, we analyzed their bacterial community’s composition and plasticity in response to salinity. Multiple cultures of Pocillopora coral-isolated Ostreob...

Background Tropical coral reefs cover only ca. 0.1% of the Earth’s surface but harbour exceptional marine biodiversity and provide vital ecosystem services to millions of people living nearby. They are currently threatened by global (e.g. climate change) and local (e.g. chemical pollution) stressors that interact in multiple ways. While global stre...

Microscopic filaments of the siphonous green algae Ostreobium (Ulvophyceae, Bryopsidales) colonize and dissolve the calcium carbonate skeletons of coral colonies, in shallow-water reef environments of contrasted salinities. Their bacterial composition and plasticity in response to salinity remain unknown. Here, we analyzed the bacteria associated w...

Background Tropical coral reefs cover ca. 0.1% of the Earth’s surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. They are currently threatened by local stressors (e.g. nutrient enrichment and chemical pollution arising from poor land management, sewage effluents, agriculture, i...

Background Tropical coral reefs cover only ca. 0.1% of the Earth’s surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. They are currently threatened by global (e.g., climate change) and local (e.g., chemical pollution) stressors that interact in different ways. While global stre...

Environmental stressors are assessed through methods that quantify their impacts on a wide range of metrics including species density, growth rates, reproduction, behaviour and physiology, as on host-pathogen interactions and immunocompetence. Environmental stress may induce additional sublethal effects, like mutations and epigenetic signatures aff...

The sugar kelp Saccharina latissima dominates many temperate coastal ecosystems, plays key ecological roles and presents important economic potential. However, its microbiota remains poorly investigated, although it could play an important role in algal fitness. In this study, we combined high throughput Illumina-based DNA sequencing and Fluorescen...

The filamentous chlorophyte Ostreobium sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic versus free-living growth forms). Here...

The “stem cells” discipline represents one of the most dynamic areas in biomedicine. While adult marine/aquatic invertebrate stem cell (MISC) biology is of prime research and medical interest, studies on stem cells from organisms outside the classical vertebrate (e.g., human, mouse, and zebrafish) and invertebrate (e.g., Drosophila, Caenorhabditis...

The “stem cells” discipline represents one of the most dynamic areas in biomedicine. While adult marine/aquatic invertebrate stem cell (MISC) biology is of prime research and medical interest, studies on stem cells from organisms outside the classical vertebrate (e.g., human, mouse, zebrafish) and invertebrate (e.g., Drosophila, Caenorhabditis) mod...

Today coral reefs are threatened by changes to seawater conditions associated with rapid anthropogenic global climate change. Yet, since the Cenozoic, these organisms have experienced major fluctuations in atmospheric CO2 levels (from greenhouse conditions of high pCO2 in the Eocene to low pCO2 ice-house conditions in the Oligocene-Miocene) and a d...

In scleractinian reef-building corals, patterns of cell self-renewal, migration and death remain virtually unknown, limiting our understanding of cellular mechanisms underlying initiation of calcification, and ontogenesis of the endosymbiotic dinoflagellate relationship. In this study, we pulse-labelled the coral Stylophora pistillata for 24 h with...

Dispersion of larval offspring is of fundamental ecological importance for sessile, marine organisms. Photosymbiotic planulae emitted by many reef-forming corals may travel over large distances before settling to form a new colony. It is not clear if the metabolic requirements of these planula larvae are met exclusively with lipid and protein reser...

Reef-building scleractinian (stony) corals are among the most efficient bio-mineralizing organisms in nature. The calcification rate of scleractinian corals oscillates under ambient light conditions, with a cyclic, diurnal pattern. A fundamental question is whether this cyclic pattern is controlled by exogenous signals or by an endogenous ‘biologic...

This chapter presents a variety of methods which can be used for the isolation, culture and in vitro monitoring of coral cells and tissue, discusses the advantages and limits of coral primary cultures, and highlights the encouraging recent progress. Cells can be isolated from coral fragments by enzyme digestion, with or without removal of divalent...

The ability of endosymbiotic Symbiodinium to fix inorganic nutrients and their translocation to the coral host is considered a key element for the growth of coral reefs in tropical coastal waters and has been a fundamental research topic for over 50 years. With pulse-chase experiments using stable isotopes and combined TEM and NanoSIMS ultrastructu...

ABSTRACT Reef-building corals form essential, mutualistic endosymbiotic associations with photosynthetic Symbiodinium dinoflagellates, providing their animal host partner with photosynthetically derived nutrients that allow the coral to thrive in oligotrophic waters. However, little is known about the dynamics of these nutritional interactions at t...

Calcium carbonate biomineralization of scleractinian coral recruits is fundamental to the construction of reefs and their survival under stress from global and local environmental change. Establishing a baseline for how normal, healthy coral recruits initiate skeletal formation is, therefore, warranted. Here, we present a thorough, multiscale, micr...

Nutritional interactions between corals and symbiotic dinoflagellate algae lie at the heart of the structural foundation of coral reefs. Whilst the genetic diversity of Symbiodinium has attracted particular interest because of its contribution to the sensitivity of corals to environmental changes and bleaching (i.e. disruption of coral-dinoflagella...

Sponges and corals have evolved various pathways for the synthesis and/or accumulation of chemical substances which have chemical defense and/or communication functions and ensure their protection and survival. This chapter focuses on chemical mediators of ecological interactions between marine sponges or corals and their environment and, within ea...

Combining culture-dependant and independant approaches, we investigated for the first time the cultivable fraction of the prokaryotic community associated with the carnivorous sponge Asbestopluma hypogea. The heterotrophic prokaryotes isolated from this tiny sponge were compared between specimens freshly collected from cave and maintained in aquari...

The chemodiversity and cultivable bacterial diversity of temperate calcareous sponges were investigated in a time series of collection of two sponges, Leuconia johnstoni (Baerida, Calcaronea) collected from the northeastern Atlantic Ocean and Clathrina clathrus (Clathrinida, Calcinea) collected from the northwestern Mediterranean Sea, using combine...

a b s t r a c t Using in situ (12 h) pulse-labeling of scleractinian coral aragonitic skeleton with stable 86 Sr isotope, the diel pattern of skeletal extension was investigated in the massive Porites lobata species, grown at 5 m depth in the Gulf of Eilat. Several microstructural aspects of coral biomineralization were elucidated, among which the...

Cell cultures from reef-building scleractinian corals are being developed to study the response of these ecologically important organisms to environmental stress and diseases. Despite the importance of cell division to support propagation, cell proliferation in polyps and in vitro is under-investigated. In this study, suspended multicellular aggreg...

Unlabelled: Metabolic interactions with endosymbiotic photosynthetic dinoflagellate Symbiodinium spp. are fundamental to reef-building corals (Scleractinia) thriving in nutrient-poor tropical seas. Yet, detailed understanding at the single-cell level of nutrient assimilation, translocation, and utilization within this fundamental symbiosis is lack...

Nitrogen storage by the dinoflagellates in response to a pulse of [15N]nitrate or [15N]aspartic acid labeling under light and ultrastructure of crystalline inclusions within dinoflagellates. TEM micrograph (A) and corresponding NanoSIMS isotopic 15N/14N image (B) of a dinoflagellate after 6 h of incubation with [15N]nitrate (30 µM). Scale bar, 2 µm...

Time course of 15N enrichment in the dinoflagellates during parallel pulse-chase experiments with [15N]ammonium, with chase under light/dark cycling versus constant darkness. Bulk analyses were carried out following conventional coral tissue dissociation and density separation of the dinoflagellate fraction from their animal host.

Principles of NanoSIMS imaging and quantification of 15N distribution in coral tissue. Here, we use coral tissue containing dinoflagellates after 1 h of exposure to [15N]ammonium (20 µM) under light to illustrate NanoSIMS imaging procedures. (A) Ultrathin sections (~70 nm thick) of coral tissue previously observed with TEM are imaged with NanoSIMS....

Nitrogen assimilation and translocation in coral epithelia. (A to D) Compared 15N enrichments measured by NanoSIMS in coral cells of all epithelia between the two pulse-chase experiments performed in this study with [15N]ammonium, i.e., under a standard light/dark cycle (14 h/10 h) and constant darkness. A clear difference in 15N enrichment appears...

NanoSIMS quantification of 15N enrichment using ROIs, defined as described in the legend of Fig. S1D

NanoSIMS measurements of the dynamics of 15N incorporation in the dinoflagellate endosymbionts and the oral epithelia of the coral host over a 4-h incubation under light with 2 µM [15N]ammonium. Significant labeling relative to the unlabeled control coral is indicated for the dinoflagellates (*) and the coral host (+). Download

EELS spectra and GC-MS data. (A) Both dinoflagellate crystalline inclusions and commercial uric acid standard display very similar spectra with a pronounced N ionization K edge at an ~400 eV energy loss, which is not apparent (arrow) for the spectrum obtained from amorphous cellular material. No Ca L2,3 ionization edge at ~345 eV was observed for t...

Supplementary materials and methods. (a) Experimental design; (b) TEM ultrastructural observations; (c) NanoSIMS isotopic imaging; (d) NanoSIMS data processing and region of interest (ROI) definitions; (e) bulk 15N/14N isotopic measurements; (f) electron diffraction, EFTEM spectrum imaging, and EELS; (g) GC-MS and GC-C-IRMS analyses of uric acid. D...

GC-C-IRMS quantification of 15N enrichment in dinoflagellate uric acid molecules from corals exposed to various incubations with 15N-dissolved inorganic nitrogen.

Best BLAST hits (E value < 1e−20 using the psi-BLAST algorithm) for proteins with high similarities to the domains of xanthine dehydrogenase and uricase present in 2 Symbiodinium species known to establish stable symbioses with coral hosts (Symbiodinium clade C3 and Symbiodinium sp. strain Mf1.05b).

Tropical and subtropical reef-building corals generally form a stable endosymbiotic association with autotrophic single-celled dinoflagellate algae, commonly known as "zooxanthellae", which is crucial for the development of coral reef ecosystems. In the present work, the spatial and temporal dynamics of trophic interactions between corals and their...

Au cours de l’évolution biologique qui a débuté sur Terre il y a plus de 3,5 milliards d’années, les organismes vivants ont développé la capacité d’associer des éléments minéraux à des molécules organiques pour former des structures minéralisées rigides. Ce phénomène, que l’on nomme la biominéralisation, est à l’origine de la formation des plaques...

The micro-and ultra-structural skeletal growth dynamics of the scleractinian coral Pocillopora damicornis (Linnaeus 1758) was studied with pulsed 86 Sr-labeling and high spatial resolution NanoSIMS isotopic imaging. Average extension rates for the two basic ultra-structural components of the skeleton, Rapid Accretion Deposits (RAD) and Thickening D...

An overview of the chemistry and microbiology of calcareous sponges (Calcispongiae) is provided, highlighting the potential of these sessile filter-feeding marine invertebrates and their associated bacteria for the discovery of new bioactive natural products. 103 compounds are presented and 116 references cited.

A method to label marine biocarbonates is developed based on a concentration enrichment of a minor stable isotope of a trace element that is a natural compo-nent of seawater, resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbon-ate is subsequently imaged with a NanoSIMS ion micro-probe to visualize the...

Assimilation of inorganic nitrogen from nutrient-poor tropical seas is an essential challenge for the endosymbiosis between reef-building corals and dinoflagellates. Despite the clear evidence that reef-building corals can use ammonium as inorganic nitrogen source, the dynamics and precise roles of host and symbionts in this fundamental process rem...

The fatty acid composition of the temperate calcareous marine sponge Leuconia johnstoni Carter 1871 (Calcaronea, Calcarea) was characterized for the first time in specimens collected off the Brittany coast of France over four years from October 2005 to September 2008. Forty-one fatty acids (FA) with chain lengths ranging from C₁₄ to C₂₂ were identi...

In contrast to siliceous sponge spicules, the biomineralization in calcareous sponges is poorly understood. In particular, the existence of a differentiated central core in calcareous spicules is still controversial. Here we combine high-spatial resolution analyses, including NanoSIMS, Raman, SXM, AFM, SEM and TEM to investigate the composition, mi...

Chemical investigation of the Mediterranean calcareous sponge Clathrina clathrus led to the isolation of large amounts of a new 2-aminoimidazole alkaloid, named clathridimine (1), along with the known clathridine (2) and its zinc complex (3). The structure of the new metabolite was assigned by detailed spectroscopic analysis. Clathridimine (1) disp...

Scleractinian corals represent a testing ground for ideas regarding biologically vs. environmentally controlled calcification. The morphology of skeletal micro-structural units (arrangement of the skeletal fibers) and their biogeochemical composition have, for a long time, been interpreted from two opposite view points: (1) as a purely physico-chem...

The biomineralization process and skeletal growth dynamics of azooxanthellate corals are poorly known. Here, the growth rate of the shallow-water dendrophyllid scleractinian coral Balanophyllia regia was evaluated with calcein-labeling experiments that showed higher lateral than vertical extension. The structure, mineralogy and trace element compos...

Cell cultures are very valuable tools in biological and medical science, providing alternative models to live animal experimentation and simplified controlled experimental models for fundamental studies of cellular mechanisms. However, to this date, marine invertebrate cell lines are not available. Primary cell cultures derived either from molluscs...