Article

Trentepohlia sp., a terrestrial chlorophyte growing on galvanised iron lamp posts

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The common green alga Trentepohlia sp. was found growing as a biofilm on galvanised iron lamp posts where it was exposed to high zinc levels and periodic desiccation. Its sole water sources were rainfall and dewfall. Photosynthesis studies using PAM techniques showed that the alga was a shade-adapted species with a very low optimum irradiance (Eopt) of about 90 μmol photons m⁻² s⁻¹, and ETRmax about 80 μmol e⁻ g⁻¹ chlorophyll-a s⁻¹. But, within minutes, it recovered from desiccation (homiochlorophyllous). The alga has a high chlorophyll-b/a ratio (0.470 ± 0.016) and conspicuous chlorophyll-b absorption in vivo, but no measureable Zn-chlorophyll derivatives were found spectrophotometrically. Mannitol experiments using up to 1.5 Osmol kg⁻¹ showed that photosynthesis in Trentepohlia sp. was highly resistant to water stress. Photosynthesis of Trentepohlia sp. was unaffected by pH even though the abundance of CO2 in the experimental medium dropped from 477 mmol m⁻³ at pH 5 to less than 1 mmol m⁻³ at pH 9. Thus, Trentepohlia sp. can use both CO2 and HCO3 ⁻ as inorganic carbon sources. Acid pH (pH 5) did not increase toxicity of Zn. Trentepohlia sp. was resistant to added Zn with little effect on photosynthetic parameters even at 30 mol m⁻³ Zn.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Integrating sphere methods have previously been limited by the prohibitive costs and the cumbersome nature of the experimental setup, particularly for field work (Runcie and Durako 2004;Ritchie and Runcie 2014) but spectrophotometers with Integrating Spheres (Taylor Sphere attachments) are now more readily available (Ritchie and Sma-Air 2020a, b). Little information is available on absorptances of non-vascular terrestrial plants and other photosynthetic organisms such as algal films of Chlorella, Trebouxia, Trentepohlia or Chlorococcum mounted on glass fibre disks (Ritchie and Runcie 2013;Ritchie 2014;Chandaravithoon et al. 2018Chandaravithoon et al. , 2020Heemboo 2021 Ritchie and, macrophytic algae (Frost-Christensen and Sand-Jensen 1992; Mercado et al. 1996;Cebrian et al. 1999;Longstaff et al. 2002;Figueroa et al. 2003Figueroa et al. , 2009, lichens (Solhaug et al. 2010;Ritchie 2014), corals etc.: Beer et al. 1998Beer et al. , 2000Enríquez et al. 2005;Stambler and Dubinsky 2005;Rodríguez-Román et al. 2006;Hennige et al. 2009). Most PAM-based estimates of ETR on such organisms are actually rETR measurements because experimentally determined absorptances were unavailable. ...
... The present study focuses on the absorptances of algaeimpregnated filter disks. However, the absorptance characteristics of photosynthetic mats or surfaces are of great interest physiologically, ecologically and from an evolutionary point of view for example microbial mats, encrusting algae, corals, stromatolites and cushions of bryophytes (Larkum et al. 2018;Hennige et al. 2009;Ritchie 2013Ritchie , 2014Ritchie and Heemboo 2021;. Absorptance of algal mats also have biotechnological significance where it may be important to know how much light is actually absorbed. ...
... Using such an integrating sphere setup of a scanning spectrophotometer would allow measurements of absorptance at the red peak of Chl d-type oxygenic organisms and for photosynthetic bacteria at near infrared wavelengths as well as over their entire photosynthetically active spectrum. Since the original development of the RAT machine our laboratory has used it for estimating absorptances for PAM-based estimates of electron transport rates in a wide variety of systems (for example : Chandaravithoon et al. 2018, Ritchie 2013, Ritchie and Heemboo 2021, Ritchie and Runcie 2013. ...
Article
Full-text available
A Reflectance Absorptance Transmittance (RAT) meter, developed for routine measurements of Abtλ nm on leaves, was used to measure absorptance of algal films mounted on glass fibre filter disks for use in PAM (Pulse Amplitude Modulation) fluorometry. Absorptance readings (Abtλ nm) are essential to quantitate the photosynthetic electron transport rate from PAM data and are also helpful if algal disks are used in an IRGA (InfraRed Gas Analyzer). Measurements were made on Synechococcus R-2 (Cyanophyceae), Acaryochloris marina (Chlorobacteria), Chlorella vulgaris (Chlorophyceae), Chaetoceros sp. (Bacillariophyceae) and Isochrysis sp. (Haptophyta) in blue (445 nm), green (525 nm) and red (625 nm) light. Plots of Abtλ vs. Chl a (mg Chl a m⁻²) or Chl d for Acaryochloris (mg Chl d m⁻²) of the algae followed exponential saturation curves (Abt%λ = Abt%λ, ∞ (1-e-k×Chl)) usually reaching asymptotes in the blue light used by blue-diode PAM machines. Synechococcus, Chlorella, Chaetoceros and Isochrysis Abt%445nm saturates ≈ 50-100 mg Chl a m⁻² (Synechococcus: Abt%445 nm, max = 77.3±0.94, ±95% conf. limits, Chlorella: Abt%445 nm, max = 77.0±2.06, Chaetoceros: Abt%445 nm, max = 80.6±1.87; Isochrysis: 83.2±8.06 mg Chl a m⁻²); Acaryochloris above about 100 mg Chl d m⁻². Asymptotic loading of cells was in general easily achieved in blue light in the case of Synechococcus, Chlorella and Acaryochloris but not in green, red or “white” light. It was difficult to achieve asymptotic loading for Chaetoceros and Isochrysis due to mucilaginous blockage of the filter disks.
... Salinity, in turn, exacerbates the effects of dehydration by further upsetting osmotic balance within cells [9]. Previous experiments on the Stichococcaceae and other aeroterrestrial algae [7,33,46,55] have demonstrated that these algae are resistant to and can recovery from desiccation, although the effect of salinity has not been studied in this context. ...
Article
Full-text available
Desiccation and high salinity are two abiotic stressors that are related in terms of their effect on water homeostasis within cells. The success of certain aeroterrestrial microalgae is influenced by their ability to cope with desiccation, and in some cases, high salinity. The microalgae of the Stichococcus clade are ubiquitous in terrestrial habitats and are known to withstand desiccation and salinity stress by accumulating secondary metabolites. Nevertheless, it remains unclear if those two related stressors have a synergistic effect. Hence, we studied the effect of salinity on desiccation on various representative taxa within the Stichococcus clade. The results showed that in contrast to other Stichococcus taxa, Pseudostichococcus was able to recover fully after desiccation, with and without salinity stress. This observation was connected to elevated proline production under salinity stress and higher proline:sorbitol ratio in Pseudostichococcus to the other strains tested. In the other taxa, increasing salinity reduced their ability to withstand desiccation. This might have severe effects on microalgae in (semi)arid regions, where salinization of soils is an increasing threat also for agriculture. The results encourage further research to be done on the possible applications of this genus in salinity bioremediation, as it seems to be comparable to other halotolerant green algae used for this purpose.
Article
Full-text available
Streptophyte algae are the ancestors of land plants, and several classes contain taxa that are adapted to an aero-terrestrial lifestyle. In this study, four basal terrestrial streptophytes from the class Klebsormidiophyceae, including Hormidiella parvula; two species of the newly described genus Streptosarcina (S. costaricana and S. arenaria); and the newly described Streptofilum capillatum were investigated for their responses to radiation, desiccation and temperature stress conditions. All the strains showed low-light adaptation (Ik < 70 μmol photons m-2 s-1) but differed in photoprotective capacities (such as non-photochemical quenching). Acclimation to enhanced photon fluence rates (160 μmol photons m-2 s-1) increased photosynthetic performance in H. parvula and S. costaricana but not in S. arenaria, showing that low-light adaptation is a constitutive trait for S. arenaria. This lower-light adaptation of S. arenaria was coupled with a higher desiccation tolerance, providing further evidence that dehydration is a selective force shaping species occurrence in low light. For protection against ultraviolet radiation, all species synthesised and accumulated different amounts of mycosporine-like amino acids (MAAs). Biochemically, MAAs synthesised by Hormidiella and Streptosarcina were similar to MAAs from closely related Klebsormidium spp. but differed in retention time and spectral characteristics in S. capillatum. Unlike the different radiation and dehydration tolerances, Hormidiella, Streptosarcina and Streptofilum displayed preferences for similar thermal conditions. These species showed a temperature dependence of photosynthesis similar to respiration, contrasting with Klebsormidium spp. and highlighting an interspecific diversity in thermal requirements, which could regulate species distributions under temperature changes.
Article
Full-text available
Sewage lagoons and wastewater ponds from industrialised swine and poultry farms are typically hypereutrophic, auxinic and dominated by purple non-sulphur bacteria and unicellular green algae both typically growing photoheterotrophically. To manage such ponds, it is essential to know the balance between oxygenic and anoxygenic photosynthesis. Typical spectrophotometric algorithms to estimate chlorophyll use 750 nm as a zero (A750 nm) but a 750 nm zero protocol is unsuitable where substantial amounts of bacteriochlorophylls are present. Algorithms were developed to estimate chlorophylls a and b (Chl a and Chl b) and bacteriochlorophyll a (BChl a) in solvent in ethanol, 7:2 acetone/ethanol and 90% acetone. The algorithms use an 850-nm absorbance zero (A850 nm) well outside the absorbance ranges of both chlorophylls and bacteriochlorophylls in solvent. There are many habitats where the presence of anoxygenic photosynthetic bacteria is unsuspected and so using a routine A750 nm zero effectively masks their presence and leads to underestimations of Chl a and Chl b. The in-solvent red peak of bacteriochlorophyll c is too close to that of Chl a for BChl c and Chl a to be resolved spectroscopically, but its presence can be easily identified from in vivo scans. The spectroscopic advantage of 90% acetone is negated by its poor quantitative extraction of pigments. Acetone/ethanol (7:2) is an excellent solvent spectroscopically and as an extractant.
Article
Full-text available
Davallia (Pachypleuria) angustata (Wall. ex Hook. & Grev.) is a common epiphytic fern that grows on tree trucks and palm trees in south-east Asia. The plant is a resurrection plant, capable of rapid recovery from desiccation, but is not a CAM plant like some other epiphytic ferns. Under well-watered conditions Davallia shows a diurnal cycle of photosynthesis with maxima in mid-morning ∼0900hours (solar time). Under optimum conditions, the optimum irradiance (Eopt)≤879.3±65.31mol photons m-2 s-1 or ∼45% of full sunlight qualifying it as a sun plant. The maximum photosynthetic electron transport rate (ETRmax) was 77.77±3.423mol e- m-2 s-1 or, on a Chl a basis 350±36.0molg-1 (Chl a) s-1. The photosynthetic efficiency (α0) is α0≤0.2404±0.02076 e- photon-1 or 1.082±0.137 e- photon m2 g-1 (Chl a). Eopt and maximum photosynthesis (ETRmax) are directly proportional to one another (y≤mx, r≤0.8813, P<<0.001). The slope of the line is the average photosynthetic efficiency at optimum irradiance (ETRmax/Eopt or αEopt≤0.07505±0.00262 e- photon-1), equivalent to a mean asymptotic photosynthetic efficiency (α0) of 0.2040±0.00712 e- photon-1. This simple relationship between ETRmax and Eopt does not appear to have been noted before. There is some accumulation of titratable acid in the morning but no accumulation of organic acids at night. Davallia is not a CAM plant. A simple pulse amplitude modulation (PAM) protocol shows that Davallia is a homiochlorophyllous resurrection plant.
Article
Full-text available
Oil Palm (Elaeis guineensis) plantations cover more than 107,000 km² in SE-Asia but there is little information on its photosynthetic characteristics. Photosynthesis in seedling, juvenile and adult Oil Palm (6 months, 1–2 y and >5 y old, respectively) were measured using blue-diode Pulse Amplitude Modulation Fluorometry (PAM). The Absorptance Factor of the leaves (Abt465nm) was measured using a Reflectance Absorptance Transmission (RAT) meter to calculate actual, rather than relative Electron Transport Rates (ETR). Midday measurements in juvenile and adult Oil Palm tree were: maximum quantum yield of Photosystem II (Ymax) in juveniles was about 0.63, Optimum irradiance (Eopt) was ≈300 μmol photon m⁻² s⁻¹. The maximum ETR (ETRmax) of juvenile plants was 24.06 ± 1.69 μmol e⁻ m⁻² s⁻¹: based on 4e⁻/O2 this is equivalent to a maximum Photosynthetic Oxygen Evolution Rate (POERmax) of 89.21 ± 6.25 μmol O2 mg Chl a⁻¹ h⁻¹. Adult Oil Palm plants have a Ymax similar to juveniles but Eopt was ≈600 μmol photon m⁻² s⁻¹. The ETRmax of adult plants was 58.97 ± 2.07 μmol e⁻ m⁻² s⁻¹: or POERmax = 305.3 ± 10.7 μmol O2 mg Chl a⁻¹ h⁻¹. Oil Palm is a classic sun plant with high photosynthetic rates at high irradiances. Photosynthetic efficiencies (α0) were high for C3 sun plants: α0 in adult plants (0.272 ± 0.018 e⁻ photon⁻¹) was higher than juvenile plants (0.204 ± 0.034 e⁻ photon⁻¹) expressed on a leaf surface area basis and on a Chl a basis (1.406 ± 0.093 vs. 0.757 ± 0.124 O2 photon⁻¹ m² g Chl a⁻¹). In juvenile and adult plants Eopt, POERmax and α0 tend to maximize about midday. In seedlings, Eopt and POERmax are highest in the early morning but maximum α0 is at about midday. Oil Palms strategically optimize photosynthesis for high irradiances and manipulate their photosynthesis vs. irradiance characteristics during the course of daylight.
Article
Full-text available
Premise of research. The encrusting arboreal lichen Dirinaria picta (Sw.) Schaer.ex Clem. (Physiaceae) is commonly found growing on tree trunks in Thailand and globally in the tropics and subtropics. Trebouxia sp. is its chlorophyte symbiont. Pulse amplitude modulation (PAM) techniques have been used to measure photosynthesis of a tropical lichen as well as its cultured symbiont. PAM technology has not been used to full advantage in lichens. Methodology. Absorptance of the thalli and glass fiber disks impregnated with cultured Trebouxia was measured with a leaf absorptance meter. PAM fluorometers measure the light reactions of photo-organisms to estimate gross photosynthesis (Pg; mol O2 m⁻² s⁻¹) from the measured electron transport rate through PSII (4 electrons per O2), provided that the absorptance of the photo-organism is known. Photosynthesis-versus-irradiance curves were measured with a blue-diode PAM machine and fitted to the waiting-in-line function. Pivotal results. The absorptance of moist active lichen in blue light is Abt%465 nm = 92.5 ± 0.529 (±95% confidence limit [CL]; n = 48). Maximum yield, maximum Pg (Pg max), quantum efficiency, and nonphotochemical quenching do not show a strong diel cycle. Dirinaria has an optimum irradiance of ≈500 μmol m⁻² s⁻¹ PPFD and a Pg max of ≈227 μmol O2 mg Chl a⁻¹ h⁻¹ (Chl a = chlorophyll a). Respiration of Dirinaria is ≈16.2 μmol O2 mg (Chl a)⁻¹ h⁻¹, so net photosynthesis is ≈211 μmol O2 mg Chl a⁻¹ h⁻¹. The Pg of Trebouxia is comparable to that of the Dirinaria lichen, but the two have different nonphotochemical quenching properties. Photosynthesis revives in dry Trebouxia in vitro within a few minutes after wetting. On a chlorophyll basis, the electron transport rates of dry and in vivo Trebouxia are closely comparable: hyphal absorption of light appears to be negligible. Conclusions. Dirinaria can tolerate high irradiances in natural conditions but is dry and dormant most of the time (poikilohydric). The desiccation resistance of Trebouxia is constitutive.
Article
Full-text available
PAM (pulse amplitude modulation) fluorometers can be used to estimate the electron transport rate (ETR) [μmol(e–) m–2 s–1] from photosynthetic yield determinations, provided the absorptance (Abtλ) of the photoorganism is known. The standard assumed value used for absorptance is 0.84 (leaf absorptance factor, AbtF). We described a reflectance-absorptance-transmittance (RAT) meter for routine experimental measurements of the actual absorptance of leaves. The RAT uses a red-green-blue (RGB) LED diode light source to measure absorptances at wavelengths suitable for use with PAM fluorometers and infrared gas analysers. Results using the RAT were compared to Abtλ spectra using a Taylor integrating sphere on bird’s nest fern (Asplenium nidus), banana, Doryanthes excelsa, Kalanchoe daigremontiana, and sugarcane. Parallel venation had no significant effect upon Abt465 in banana, Doryanthes, a Dendrobium orchid, pineapple, and sugarcane, but there was a slight difference in the case of the fern A. nidus. The average Abt465 (≈ 0.96) and Abt625 (≈ 0.89) were ≈14% and 6% higher than the standard value (AbtF = 0.84). The PAR-range Abt400–700 was only ≈ 5% higher than the standard value (≈ 0.88) based on averaged absorptance from the blue, green, and red light data and from where the RGB-diode was used as a ‘white’ light source. In some species, absorptances at blue and red wavelengths are quite different (e.g. water lily). Reflectance measurements of leaves using the RAT would also be useful for remote sensing studies.
Article
Full-text available
Two newly isolated strains of green algae from alpine regions were compared physiologically at different culture ages (1, 6, 9 and 15 months). The strains of Zygnema sp. were from different altitudes ('Saalach' (S), 440 m above sea level (a.s.l.), SAG 2419 and 'Elmau-Alm' (E-A), 1,500 m a.s.l., SAG 2418). Phylogenetic analysis of rbcL sequences grouped the strains into different major subclades of the genus. The mean diameters of the cells were 23.2 μm (Zygnema S) and 18.7 μm (Zygnema E-A) but were reduced significantly with culture age. The photophysiological response between the strains differed significantly; Zygnema S had a maximal relative electron transport rate (rETR max) of 103.4 μmol electrons m(-2) s(-1), Zygnema E-A only 61.7 μmol electrons m(-2) s(-1), and decreased significantly with culture age. Both strains showed a low-light adaption and the absence of strong photoinhibition up to 2,000 μmol photons m(-2) s(-1). Photosynthetic oxygen production showed similar results (P max Zygnema S, 527.2 μmol O2 h(-1) mg(-1) chlorophyll (chl.) a, Zygnema E-A, 390.7 μmol O2 h(-1) mg(-1) chl. a); the temperature optimum was at 35 °C for Zygnema S and 30 °C for Zygnema E-A. Increasing culture age moreover leads to the formation of pre-akinetes, which accumulate storage products as revealed by light and transmission electron microscopy. Desiccation at 84 % relative air humidity (RH) lead to a reduction of the effective quantum yield of photosystem II (PSII) (ΔFv/Fm') to zero between 90 to 120 min (Zygnema S) and between 30 to 60 min (Zygnema E-A), depending on the culture age. A partial recovery of ΔFv/Fm' was only observed in older cultures. We conclude that pre-akinetes are crucial for the aeroterrestrial lifestyle of Zygnema.
Article
Full-text available
Introduction: Many biological response curves commonly assume a sigmoidal shape that can be approximated well by means of the 4-parameter nonlinear logistic equation, also called the Hill equation. However, estimation of the Hill equation parameters requires access to commercial software or the ability to write computer code. Here we present two user-friendly and freely available computer programs to fit the Hill equation - a Solver-based Microsoft Excel template and a stand-alone GUI-based "point and click" program, called HEPB. Methods: Both computer programs use the iterative method to estimate two of the Hill equation parameters (EC50 and the Hill slope), while constraining the values of the other two parameters (the minimum and maximum asymptotes of the response variable) to fit the Hill equation to the data. In addition, HEPB draws the prediction band at a user-defined confidence level, and determines the EC50 value for each of the limits of this band to give boundary values that help objectively delineate sensitive, normal and resistant responses to the drug being tested. Results: Both programs were tested by analyzing twelve datasets that varied widely in data values, sample size and slope, and were found to yield estimates of the Hill equation parameters that were essentially identical to those provided by commercial software such as GraphPad Prism and nls, the statistical package in the programming language R. Discussion: The Excel template provides a means to estimate the parameters of the Hill equation and plot the regression line in a familiar Microsoft Office environment. HEPB, in addition to providing the above results, also computes the prediction band for the data at a user-defined level of confidence, and determines objective cut-off values to distinguish among response types (sensitive, normal and resistant). Both programs are found to yield estimated values that are essentially the same as those from standard software such as GraphPad Prism and the R-based nls. Furthermore, HEPB also has the option to simulate 500 response values based on the range of values of the dose variable in the original data and the fit of the Hill equation to that data.
Article
Full-text available
Shallow ponds with rapidly photosynthesising cyanobacteria or eukaryotic algae are used for growing biotechnology feedstock and have been proposed for biofuel production but a credible model to predict the productivity of a column of phytoplankton in such ponds is lacking. Oxygen electrodes and Pulse Amplitude Modulation (PAM) fluorometer technology were used to measure gross photosynthesis (P G) vs. irradiance (E) curves (P G vs. E curves) in Chlorella (chlorophyta), Dunaliella salina (chlorophyta) and Phaeodactylum (bacillariophyta). P G vs. E curves were fitted to the waiting-in-line function [P G = (P Gmax × E/E opt) × exp(1 – E/E opt)]. Attenuation of incident light with depth could then be used to model P G vs. E curves to describe P G vs. depth in pond cultures of uniformly distributed planktonic algae. Respiratory data (by O 2 -electrode) allowed net photosynthesis (P N) of algal ponds to be modelled with depth. Photoinhibition of photosynthesis at the pond surface reduced P N of the water column. Calculated optimum depths for the algal ponds were: Phaeodactylum, 63 mm; Dunaliella, 71 mm and Chlorella, 87 mm. Irradiance at this depth is ≈ 5 to 10 µmol m –2 s –1 photosynthetic photon flux density (PPFD). This knowledge can then be used to optimise the pond depth. The total net P N [µmol(O 2) m –2 s –1 ] were: Chlorella, ≈ 12.6 ± 0.76; Dunaliella, ≈ 6.5 ± 0.41; Phaeodactylum ≈ 6.1 ± 0.35. Snell's and Fresnel's laws were used to correct irradiance for reflection and refraction and thus estimate the time course of P N over the course of a day taking into account respiration during the day and at night. The optimum P N of a pond adjusted to be of optimal depth (0.1–0.5 m) should be approximately constant because increasing the cell density will proportionally reduce the optimum depth of the pond and vice versa. Net photosynthesis for an optimised pond located at the tropic of Cancer would be [in t(C) ha –1 y –1 ]: Chlorella, ≈ 14.1 ± 0.66; Dunaliella, ≈ 5.48 ± 0.39; Phaeodactylum, ≈ 6.58 ± 0.42 but such calculations do not take weather, such as cloud cover, and temperature, into account.
Article
Full-text available
Communities of terrestrial green algae occurring at the bases of old, weathered walls are widespread in temperate urban areas, but have been virtually unstudied. In spring and summer 2002 we examined collections from a number of cities in northern Europe (Galway, Dublin, Manchester, Durham, Copenhagen) and southern Europe (Oviedo, Leon, Bordeaux, Marseilles, Pisa) and from several localities in western Ireland. Seventeen taxa of green and blue-green algae were found. Filamentous green algae were the most common forms and the assemblages could be subdivided into two different types: a Prasiolales assemblage (in which the dominant forms are Rosenvingiella sp. and Prasiola calophylla) and a Klebsormidium assemblage (dominated by species of Klebsormidium). The patterns of distribution of the most abundant species showed marked differences between the cities sampled, but no significant effect of latitude. The vegetation of each of the cities examined was generally assignable either to the Prasiolales assemblage (Galway, Dublin, Durham, Oviedo and Leon) or the Klebsormidium assemblage (Manchester, Copenhagen, Bordeaux, Marseilles and Pisa). For western Ireland, no significant variation was detected in the assemblages at different distances from the Atlantic. Climatic factors operating at a scale of hundreds of kilometres are considered the most important in determining the relative distribution of these assemblages. The Prasiolales assemblage is primarily associated with the rainy and cool Atlantic regions of Europe, whereas the Klebsormidium assemblage is dominant in continental and Mediterranean areas. The composition of these assemblages shows extremely limited variation on small spatial scales and no significant variation is detectable between different areas of the same city or town for any of the most common species. Physiological attributes of the Prasiolales and Klebsormidium in relation to different climatic regimes are considered to play a fundamental role in the distributional patterns of these algae.
Article
Full-text available
Concrete, stone, brick, plaster, wood, plastic, painted surfaces and metal are all colonised by bacteria, algae and fungi which accelerate theirdeterioration. The mechanisms of deterioration, the main microbial genera involved and factors which may affect the degree of colonisation and attack are discussed. The chief factor determining microbial growth on constructional materials is moisture. Thus it is important for architects and engineers to consider critical points in the humidity profile of a building at the design stage. Damp surfaces are readily colonised by microbial cells settling from the air. This leads to the formation of a biofilm, which can trap dust and other particulate materials, increasing its disfiguring effect. In addition, the biofilm can act as a reservoir for potentially dangerous microorganisms such as the bacteria responsible for legionnaires’ disease and allergenic fungal and actinomycete spores. Materials may be protected against microbial growth by the use of biocides. The use of such toxic agents is critically reviewed.
Article
Full-text available
The taxonomy and distribution of the species of Trentepohlia and Printzina in the Hawaiian Islands were studied by examination of field collections and herbarium specimens from Bernice P. Bishop Museum, Honolulu (BISH). Eight taxa attributable to these genera were recorded in the field: Printzina bosseae var. samoensis, P. effusa, P. lagenifera, Trentepohlia abietina, T. abietina var. tenue, T. arborum, Trentepohlia cf. flava and T. umbrina. The record of Trentepohlia aurea, based on some specimens deposited in BISH, is rejected. Growth and reproduction of some entities (P. bosseae var. samoensis, P. effusa, P. lagenifera and T. arborum) were examined in culture. In the Hawaiian Islands these algae grow primarily on tree bark and are rarely found on other types of substrata. Reproduction takes place by production of presumptive biflagellate gametangia in P. lagenifera, T. abietina and Trentepohlia cf. flava and by release of zoosporangia in P. bosseae var. samoensis and T. arborum; in P. effusa, both types of reproductive structures were found. Vegetative growth was the only form of reproduction found in culture for the species for which isolation was possible. The taxonomic position of the species collected and implications for the conservation of the Trentepohliaceae in tropical regions are discussed.
Article
Full-text available
Algae have adopted two primary strategies to maximize the performance of Rubisco in photosynthetic CO2 fixation. This has included either the development of a CO2-concentrating mechanism (CCM), based at the level of the chloroplast, or the evolution of the kinetic properties of Rubisco. This review examines the potential diversity of both Rubisco and chloroplast-based CCMs across algal divisions, including both green and nongreen algae, and seeks to highlight recent advances in our understanding of the area and future areas for research. Overall, the available data show that Rubisco enzymes from algae have evolved a higher affinity for CO2 when the algae have adopted a strategy for CO2 fixation that does not utilise a CCM. This appears to be true of both Green and Red Form I Rubisco enzymes found in green and nongreen algae, respectively. However, the Red Form I Rubisco enzymes present in nongreen algae appear to have reduced oxygenase potential at air level of O2. This has resulted in a photosynthetic physiology with a reduced potential to be inhibited by O2 and a reduced need to deal with photorespiration. In the limited number of microalgae that have been examined, there is a strong correlation between the existence of a high-affinity CCM physiology and the presence of pyrenoids in all algae, highlighting the potential importance of these chloroplast Rubisco-containing bodies. However, in macroalgae, there is greater diversity in the apparent relationships between pyrenoids and chloroplast features and the CCM physiology that the species shows. There are many examples of microalgae and macroalgae with variations in the presence and absence of pyrenoids as well as single and multiple chloroplasts per cell. This occurs in both green and nongreen algae and should provide ample material for extending studies in this area. Future research into the function of the pyrenoid and other chloroplast features, such as thylakoids, in the operation of a chloroplast-based CCM needs to be addressed in a diverse range of algal species. This should be approached together with assessment of the coevolution of Rubisco, particularly the evolution of Red Form I Rubisco enzymes, which appear to achieve superior kinetic characteristics when compared with the Rubisco of C3 higher plants, which are derived from green algal ancestors.Key words: Rubisco, CO2-concentrating mechanism, carbonic anhydrase, aquatic photosynthesis, algae, pyrenoids, inorganic carbon.
Chapter
Full-text available
Field crops are frequently exposed to drought and high temperature in the field. As the stress tolerance is the major target of many research and breeding programmes, the efficient and reliable tools and methods useful in screening of the heat and drought stress effects are required. The techniques based on measurement of chlorophyll fluorescence induction belong recently to fundamentals of plant stress research; however, in most cases the very basic tools are used and its potential is not utilised sufficiently. This proposed chapter tries to summarise the knowledge, starting from basic theory through parameters and useful experimental protocols and results up to special kinds of application of chlorophyll fluorescence techniques. In addition to generally used pulse-amplitude-modulated (PAM) method with saturation pulse analysis, the fast fluorescence kinetics, the fluorescence imaging, as well as simultaneous measurements of chlorophyll fluorescence with other parameters and their potential application in drought and heat-stress research are discussed.
Article
Full-text available
Examination of Trentepohlia Martius species indicated significant morphological diversity within the genus. This diversity forms the basis for the description of a new genus, Printzina Thompson and Wujek. The generic taxonomy is based on the nature of its superficial growth on leaves or twigs and a papilla pore basal on the sporangium, adjacent to the area of attachment. Certain nomen-clatural treatments were required: the transfer of nine species from Trentepohlia and the description of one new species, Printzina ampla.
Article
Full-text available
On the basis of field and culture investigations, five species of the genera Trentepohlia and Printzina were found to occur in urban habitats in western Ireland: Trentepohlia abietina (Flotow) Hansgirg, T. aurea (Linnaeus) Martius, T. iolithus (Linnaeus) Wallroth, T. cf. umbrina (Kützing) Bornet, and Printzina lagenifera (Hildebrandt) Thompson et Wujek. These species formed perennial populations on a variety of substrata. T. abietina occurred on bark of trees; T. cf. umbrina occurred on stone walls; and P. lagenifera grew on several substrata, mainly cement and asbestos sheeting. T. aurea and T. iolithus were found on old concrete and cement walls; in particular, the latter species formed characteristic, extensive, deep-red patches on many buildings. In culture, best growth and reproduction of these species were observed at 10 and 15° C, 16:8 h light:dark. Both in culture and in the field, reproduction took place by release of biflagellate swarmers behaving as asexual spores, germinating to produce new plants without any evidence of sexual fusion; release of biflagellate swarmers in the field was generally observed in all seasons throughout a whole annual cycle. Confirmation of the occurrence of sexual reproduction in Trentepohlia was not obtained.
Chapter
Full-text available
Over the past millions of years the land on our planet has been the testing ground for many experiments or, more dramatically, the battleground for many invasions. A myriad of ancestral plant forms came from the sea and lakes to exploit the terrestrial environment. Those life forms were algae, simple photoautotrophic organisms that eventually prepared the land for the terrestrial flora and fauna that were to follow. They successfully conquered the land in terms of making it a useable new habitat for themselves and developed new forms and processes to adapt. Those plant “invaders” or “conquerors” are represented today by algae living among us populating soils and other terrestrial habitats. Most of the photosynthetic organisms that occur nowadays in aquatic habitats belong to this heterogeneous category generally called algae. These organisms are phylogenetically unrelated, or only distantly related, and differ enormously in terms of gross morphology, ultrastructure, biochemical traits and many other important features. Several lineages of algae successfully colonized terrestrial environments. Although from the ecological point of view the most important conquest of land was that of the green algae of the streptophytan lineage (those that gave rise to land plants), several other groups did succeed in becoming terrestrial. Representatives of these lineages are presently commonly found in terrestrial environments and unlike land plants, have maintained a very similar morphology to that of their aquatic relatives. The Charophyta and the Chlorophyta sensu stricto are the two groups of eukaryotic algae that along with the prokaryotic Cyanobacteria (blue-green algae) have been most successful in colonizing terrestrial environments.
Article
Full-text available
The aerial microalga Trentepohlia aurea has beeninvestigated in relation to removal characteristics of nitrate, nitrite,ammonium and phosphate ions. When the alga was cultured in medium with veryhighconcentrations of ammonium, nitrate and phosphate ions, it showed relativelyhigh growth and removal rates. It also grew quite well with high nitriteconcentration (< 141="" mg="">2-N L–1).The removal rate was 0.28 mg NO2-N L–1day–1 in the 40-day culture, when it was cultured in modifiedBold's basal medium with added 51 mg NO2-NL–1. In addition, we examined simultaneous removal of nutrientions. The biomass was 1.5 times higher in medium which N- and P-sourcesufficient than in ordinary medium. Higher removal ratios of nitrite andnitratefrom medium were shown in a 30-day culture, reaching 37% and 32%, respectively.It is concluded that T. aurea has the potential for use inthe purification of wastewater.
Chapter
Full-text available
Aeroterrestrial phototrophic microorganisms typically form conspicuous biofilms in all climatic zones at the interface between any type of solid substratum and the atmosphere. In temperate regions such as North-Western Europe, eukaryotic green microalgae (Chlorophyta) are the most abundant aeroterrestrial organisms (see also Rindi, this volume), whereas cyanobacteria dominate warm-temperate to tropical regions (Ortega-Calvo et al., 1995; Tomaselli et al., 2000). Aeroterrestrial green microalgae grow epiphytically and epilithically on natural surfaces such as tree bark, soil and rock, and are known to be the photobionts of lichens (Ettl and Gärtner, 1995). These organisms also occur in urban areas on anthropogenic surfaces such as roof tiles, concrete, building facades and other artificial surfaces where they cause aesthetically unacceptable discolouration known as patinas and incrustations (Gaylarde and Morton, 1999; Tomaselli et al., 2000).
Chapter
Full-text available
Eukaryotic algae and cyanobacteria occur virtually in every terrestrial habitat on our planet. Organisms belonging to these groups are present even in some of the most extreme terrestrial environments, such as rocks in hot and cold deserts (Friedmann and Ocampo-Friedmann, 1984), Antarctic soils (Broady, 1996) and highly acidic post-mining sites (Lukešová, 2001). As early as the beginning of the nineteenth century, it was realized that microalgae occur also on walls, masonry and other man-made substrata (e.g. Dillwyn, 1809; Agardh, 1824); however, very little attention has been devoted to this type of algal communities until recently. Cities are artificial environments in which artificial substrata (such as concrete, asphalt, glass and metal) provide the largest part of the surfaces available for the colonization of microorganisms. The surfaces of many urban buildings are exposed to full sunlight; organisms growing on such surfaces are therefore frequently subjected to extremely high light irradiance, high levels of UV radiation and extreme dehydration (Crispim and Gaylarde, 2004; Karsten et al., 2005). The temperature of walls and roofs is subjected to a high range of variation and, in tropical regions, can reach 60–70ºC (Tripathi et al., 1990). Most urban habitats are also affected by large amounts of pollutants, such as gases (SO2, CO, NOX, hydrocarbons, ozone), aerosols, dusts and heavy metals (Seaward, 1979; John, 1988). Due to such a negative combination of factors for organisms of aquatic origin, for microalgae and cyanobacteria cities can be certainly considered extreme environments. Reports on algae and cyanobacteria from urban habitats have gradually appeared in the last few decades. Most studies on this subject concern European, Asiatic and South American cities; at present, there is almost no information published for other continents. In general, the knowledge of the diversity and ecology of these communities is still rudimentary, because most studies have focused much more on the biodeterioration operated by these organisms on artificial surfaces than on their biology. In this chapter, the information currently available on cyanobacteria and green algae of urban environments is summarized. General aspects of the diversity and distribution of these organisms in urban habitats are discussed, and the composition and ecology of the most common algal assemblages in these environments are described in detail.
Article
Full-text available
The response to different levels of metal pollution by assemblages of microbenthic algae and bacteria was investigated in a lowland stream. Colonized glass-discs and samples of natural assemblages on coarse sand were used to test zinc tolerance. Tolerance was characterized by measuring inhibition of 14C-incorporation in microalgae and inhibition of 3H-thymidine incorporation in bacteria. Bacterial assemblages on both glass and sand from a high zinc and cadmium site were resistant to zinc when compared to populations from a cleaner upstream site. Algae from the strongly polluted site were only slightly affected by the highest test concentrations of zinc, in contrast to other algal communities. A change towards metal tolerant bacteria and algae was indicated and seems to occur despite the strong binding of metals by precipitates of iron hydroxide and organic deposits in the biofilm. The observations were compared with published data on short-term and long term zinc toxicity in algae and bacteria. The gradual changes in micro- and macrobenthos under high metal loads is discussed.
Article
Full-text available
We discovered natural photosynthesis using Zn-containing bacteriochlorophyll α in an acidophilic bacterium Acidiphilium rubrum. Chemical analysis of the cell extracts gave a 13 : 2 :1 molar ratio of Zn-bacteriochlorophyll α : Mg-bacteriochlorophyll α : bacteriopheophytin α. Most of the pigments are associated with fully active reaction center and light-harvesting complexes analogous to those in purple photosynthetic bacteria. The finding indicates an unexpectedly wide variability of photosynthesis.
Article
Full-text available
The in vivo substitution of magnesium, the central atom of chlorophyll, by heavy metals (mercury, copper, cadmium, nickel, zinc, lead) leads to a breakdown in photosynthesis and is an important damage mechanism in heavy metal-stressed plants. In this study, a number of methods are presented for the efficient in situ detection of this substitution (i.e. in whole plants or in chloroplasts). While macroscopic observations point to the formation of heavy metal chlorophylls at higher concentrations, fluorescence microscopy enables the detection of this reaction at very low substitution rates. Therefore, the course of the reaction can be followed by continuously measuring the fluorescence of whole plants. Furthermore absorbance spectroscopy of whole cells or isolated chloroplasts also enables the in situ detection of heavy metal chlorophylls. These methods provide practicable approaches in detecting the formation of these compounds in situ, avoiding artefacts that might occur using extraction methods based on polar solvents. In addition to the new methods for in situ detection, an extreme heterogeneity in the reaction of cells in the same tissue upon heavy metal stress was observed: while some cells are already disintegrating, others still show normal fluorescence and photosynthetic activity. Measurements of fluorescence kinetics gave a further hint that in high light intensity a substitution of Mg by heavy metals might take place specifically in PS II reaction centres.
Article
Full-text available
Subaerial green microalgae represent a polyphyletic complex of organisms, whose genetic diversity is much higher than their simple morphologies suggest. The order Trentepohliales is the only species-rich group of subaerial algae belonging to the class Ulvophyceae and represents an ideal model taxon to investigate evolutionary patterns of these organisms. We studied phylogenetic relationships in two common genera of Trentepohliales (Trentepohlia and Printzina) by separate and combined analyses of the rbcL and 18S rRNA genes. Trentepohlia and Printzina were not resolved as monophyletic groups. Three main clades were recovered in all analyses, but none corresponded to any trentepohlialean genus as defined based on morphological grounds. The rbcL and 18S rRNA datasets provided congruent phylogenetic signals and similar topologies were recovered in single-gene analyses. Analyses performed on the combined 2-gene dataset inferred generally higher nodal support. The results clarified several taxonomic problems and showed that the evolution of these algae has been characterized by considerable morphological convergence. Trentepohlia abietina and T. flava were shown to be separate species from T. aurea; Printzina lagenifera, T. arborum and T. umbrina were resolved as polyphyletic taxa, whose vegetative morphology appears to have evolved independently in separate lineages. Incongruence between phylogenetic relationships and traditional morphological classification was demonstrated, showing that the morphological characters commonly used in the taxonomy of the Trentepohliales are phylogenetically irrelevant.
Article
In this work, a reddish biocolonization composed mainly by Trentepohlia algae affecting a synthetic building material from a modern building from the 90s located in the Bizkaia Science and Technology Park (Zamudio, North of Spain) was characterized and its ability to accumulate metals coming from the surrounding atmosphere was evaluated. To asses if these biofilms can act as bioindicators of the surrounding metal pollution, a fast non-invasive in situ methodology based on the use of hand-held energy dispersive X-ray fluorescence (HH-ED-XRF) was used. In order to corroborate the in situ obtained conclusions, some fragments from the affected material were taken to analyze the metal distribution by means of micro-energy dispersive X-ray fluorescence spectroscopy (μ-ED-XRF) and to confirm the presence of metal particles deposited on it using Scanning Electron Microscopy coupled to an Energy Dispersive Spectrometer (SEM-EDS). In order to confirm if Trentepohlia algae biofilms growing on the surface of building materials could be a fast way to in situ provide information about the surrounding metal pollution, a second Trentepohlia algae biofilm growing on a different kind of material (sandstone) was analyzed from an older historical building, La Galea Fortress (Getxo, North of Spain).
Article
Accumulation of arsenic in plants is a serious Southeast Asian environmental problem. Photosynthesis in the small aquatic angiosperm Wolffia arrhiza is very sensitive to arsenic toxicity, particularly in water below pH 7 where arsenite (As (OH) 3) (AsIII) is the dominant form; at pH 47 AsO 4 2 À (As (V) predominates). A blue-diode PAM (Pulse Amplitude Fluorometer) machine was used to monitor photosynthesis in Wolffia. Maximum gross photosynthesis (Pg max) and not maximum yield (Y max) is the most reliable indicator of arsenic toxicity. The toxicity of arsenite As(III) and arsenate (H 2 AsO 4 2 À) As (V) vary with pH. As(V) was less toxic than As(III) at both pH 5 and pH 8 but both forms of arsenic were toxic (490% inhibition) at below 0.1 mol m À 3 when incubated in arsenic for 24 h. Arsenite toxicity was apparent after 1 h based on Pg max and gradually increased over 7 h but there was no apparent effect on Y max or photosynthetic efficiency (α 0).
Article
Photosynthesis is the key process that is affected by dehydration in plants. Desiccation-tolerant resurrection plants can survive conditions of very low relative water content. During desiccation, photosynthesis is not operational, but is recovered within a short period after rehydration. While homoiochlorophyllous resurrection plants retain their photosynthetic apparatus during desiccation, poikilochlorophyllous resurrection species dismantle chloroplasts and degrade chlorophyll but resynthesize them again during rehydration. Dismantling the chloroplasts avoids the photooxidative stress in poikilochlorophyllous resurrection plants, whereas it is minimized in homoiochlorophyllous plants through the synthesis of antioxidant enzymes and protective proteins or metabolites. Although the cellular protection mechanisms in both of these species vary, these mechanisms protect cells from desiccation-induced damage and restore photosynthesis upon rehydration. Several of the proteins synthesized during dehydration are localized in chloroplasts and are believed to play major roles in the protection of photosynthetic structures and in recovery in resurrection species. This review focuses on the strategies of resurrection plants in terms of how they protect their photosynthetic apparatus from oxidative stress during desiccation without membrane damage and with full recovery during rehydration. We review the role of the dehydration-induced protection mechanisms in chloroplasts and how photosynthesis is restored during rehydration.
Article
1. The paper chromatographic separation of chloroplast pigments has been studied with 43 different solvents and solvent mixtures. Developing solvents recommended by previous workers were studied comparatively, and a number of solvents not previously used for this purpose were also examined. 2. Sixteen of the solvents and solvent mixtures gave satisfactory separation of the chloroplast pigments. 3. According to the type of separation produced, the solvents and solvent mixtures may be classified into four types. 4. Solvents which may be used for paper chromatography of chloroplast pigments include propylene glycol, dicthylene glycol, o-dichlorobenzene, cyclohexane, and methyl cyclohexane, none of which have been previously used for this purpose.
Article
This study aimed to determine the contrasting ecotoxicity effects of zinc on growth and photosynthesis in a neutrophilic (Chlamydomonas reinhardtii) and an extremophilic (Cyanidium caldarium) alga. Experiments were carried out to see if cells acclimated to zinc would respond differently to cells that were unexposed to zinc. The study also aimed to see if extremophiles displayed different acclimation properties to neutrophiles. Results showed that the neutrophilic alga C. reinhardtii, was more susceptible to free zinc and had a lower IC50 value than the extremophile, however its stress response protected the photosynthetic apparatus. Upon acclimation, the photosynthetic abilities of C. reinhardtii were not significantly compromised when exposed to toxic levels of free zinc. On the other hand, C. caldarium had a stress response which allowed it to tolerate significantly higher amounts of free zinc in its environment compared to C. reinhardtii , however the stress response did not protect the photosynthetic apparatus, and upon acclimation C. caldarium was no better equipped to protect its photosynthetic integrity than unexposed cells.
Article
The effect of 12 heavy metal compounds on the absorption spectrum of whole cells of Chorella, and of chlorophyll extracted in four different solvent systems is investigated. The study included metals already known to effect chlorophyll such as zinc chloride (ZnCl2), mercuric chloride (HgCl2), cupric chloride (CuCl2), lead nitrate (Pb[NO3]2), methylmercuric chloride (MMC) and phenylmercuric acetate (PMA). All of the metal compounds tested decreased the level of chlorophyll in cells or in solvent extracts of chlorophyll, although the amount of degradation was highly solvent dependent with the greatest decrease being in methanol extracts. In whole cells of Chorella, MMC and PMA decreased the levels of chlorophyll more than in extracted chlorophyll, and this may be related to their greater ability to cross cell membranes. Cupric chloride was the only heavy metal ion tested that caused a shift in the chlorophyll spectrum in both whole cells and in solvent extracts. The most likely explanation for this is that copper is able to displace the magnesium from the chlorophyll molecule. The amount of chlorophyll degradation by metals was strongly correlated to their standard redox potentials, and the differences observed in the four solvent systems was correlated to their dielectric constants.
Article
Twenty bryophyte species were tested for photosynthetic uptake of bicarbonate by immersing plants in 2.0 mM and 0.2 mM NaHCO3 and monitoring rise in pH. Equilibrium values were clustered around pH 9.0 and pH 8.0 in the two solutions, indicating limitation by free CO2 and inability to use bicarbonate. Anthoceros husnotii reached a maximum pH value of 9.5 in 2.0 mM NaHCO3, suggesting possible, although inefficient, bicarbonate uptake. Four species of bicarbonate-using plants tested for comparison gave final pH values in the range of 10.1 to 10.9. Field measurements gave results consistent with the laboratory experiments. Availability of CO2 to bryophytes growing in different aquatic habitats is discussed and their ecology is considered in light of the results.
Article
The photosynthetic rates of Trentepohlia odorata (L.) Martius growing on wall surfaces in Singapore changed throughout the day with a maximum in midmorning and decreasing thereafter during the day. Optimum temperature for photosynthesis was 25° C. Different levels of air humidity also affected photosynthetic rates with low relative humidity reducing the rates and efficiency of photosynthesis. Our results suggested that T. odorata was able to maximize its rate of photosynthesis before photoinhibitory light levels were reached and that its growth might be dependent on high levels of atmospheric relative humidity, which may serve as a source of water supply for the alga.
Article
Miniaturized pulse-amplitude modulated photosynthesis yield analysers are primarily designed for measuring effective quantum yield (ΔF/Fm′) of photosystem II under momentary ambient light conditions in the field. Although this provides important ecophysiological information, it is often necessary to learn more about the potential intrinsic capacities of leaves by measuring light-response curves. Thus, instruments provide light-curve programmes, where light intensities are increased in short intervals and instant light-response curves are recorded within a few minutes. This method can be criticized because photosynthesis will most likely not be in steady state. This technical report shows that with the appropriate precautions instant light curves can nevertheless provide reliable information about cardinal points of photosynthesis. First, the geometry of the light source of the instrument in relation to the quantum sensor must be considered and quantum sensor readings must be corrected. Second, the measurements of the light-response curves must be compared with readings of effective quantum yield of photosystem II under ambient light conditions where photosynthesis is in steady state. This may show that in the critical range of the light curves either both measurements perfectly coincide or are offset against each other by a constant value (examples are given here). In the first case results of light curves can be taken at face values, and in the second case a simple correction can be applied. With these precautions and careful interpretations instant light-response curves can be an enormous advantage in ecophysiological field work.
Article
Algal communities inhabiting four calamine mine spoils differing in time since cessation of exploitation and loaded with high concentrations of zinc (20,284–61,599μg g−1 soil DW), lead (2,620–3,885μg g−1 DW) and cadmium (104–232μg g−1 DW) were studied. In dump soils of slightly alkaline pH (7.28–7.52) and low nutrient (P - PO3 - 4 P - PO^{{3 - }}_{4} , N - NH + 4 N - NH^{ + }_{4} , N - NO - 3 N - NO^{ - }_{3} ) concentrations, chlorophyll a content ranged from 0.41 to 2.27μg g−1 soil DW. In total, 23 algal species were recorded. Chlorophyta were the dominant taxonomic group (42–55% of all identified species) followed by Cyanobacteria (28–36%) and Heterokontophyta (13–21%). The highest species richness (18) was observed in the oldest dump (120years old) with natural succession, while in younger dumps it was lower (11–15). Total algal abundance ranged between 5.5 and 19.1 × 102 ind. g−1 soil DW, and values of Margalef’s diversity indices (1.59–2.25) were low. These results may suggest that both high concentrations of heavy metals and low nutrient content influenced the algal communities in all the dumps studied. The differences in algal microflora observed between tailing dumps may indicate that habitat quality improved with time and that algae isolated from Zn/Pb-loaded soils may be Zn/Pb-resistant ecotypes of ubiquitous species.
Chapter
Chlorophyll (Chl) assays derive their importance from the essential role of Chls in the harvesting of solar energy and its transduction to biologically useful chemical energy (ATP) and reducing power (NADPH or NADH) during photosynthesis in higher plants, marine and aquatic algae, and in photosynthetic bacteria. Accurate determination of Chl a and b concentrations and of Chl a/b ratios has been an essential tool in photosynthesis research in higher plants and green algae. Spectrophotometric and spectrofluorimetric assays, relying on the characteristic absorption and fluorescence properties of the chlorophylls, will be described and accurate data presented for spectrophotometric assays in a wide variety of solvents.
Article
Rapid light curves provide detailed information on the saturation characteristics of electron transport, as well as the overall photosynthetic performance of a plant. Rapid light curves were collected from samples of Zostera marina grown under low and high-light conditions (50 and 300 μmol photons m−2 s−1) and the distinctive patterns of RLC parameters are discussed, in terms of differential sink capacity and PSII reaction centre closure. Derived cardinal points of a rapid light curve (α, Ek and rETRmax) describe the photosynthetic capacity of a seagrass leaf, its light adaptation state and its capacity to tolerate short-term changes in light. The shapes of the corresponding F and F′m curves also provide information on the development of the trans-thylakoid proton gradient and thermal energy dissipation. Low-light leaves showed limited photosynthetic capacity and reduced activity of non-photochemical quenching pathways, whereas photosynthesis of high light leaves were not limited and showed an elevated level of non-photochemical quenching, possibly associated with xanthophyll cycle activity. Light-dark kinetics are also discussed in relation to relaxation of non-photochemical quenching and its various components. A curve fitting model is recommended based on the double exponential decay function. In this paper, we explain the fundamental aspects of a RLC, describe how it reflects the response to light exposure of a leaf, how to interpret these curves, and how to quantitatively describe and compare RLCs.
Article
The apparent constants (K'i) for the ionization of carbonic acid in seawater at various salinities (S,%.) have been fit to equations of the form ln whereKi is the thermodynamic ionization constant in water, Ai, and Bi are adjustable parameters. The temperature dependence (TK) of Ki, Ai and Bi were of the form, a0 + a1/T + a3 ln T. Equations of similar forms have been used to analyze the ionization constants for water and boric acid and the solubility product of calcite in seawater. The effect of pressure on the apparent constants () have been fit to equations of the form ln where the volume (ΔV) and compressibility (ΔK) changes are polynomial functions of temperature. The equations generated for various açids in seawater have been used to examine the carbonate system in seawater. Equations relating the NBS and Tris pH scales have been derived as well as equations of pH as a function of temperature and pressure. The equations from Hansson (1972, Ph.D. Thesis, University of Göteborg, Sweden) and Mehrbachet al. (1973, Limnol. Oceanogr.18, 897–907) have been used to examine the components of the carbonate system. At a fixed total alkalinity and total carbon dioxide, differences of ±0.01 m-equiv kg−1 in HCO−3 and CO2−3 were found; however, the [CO2] and Pco2 are nearly the same. The contribution of borate ion, B(OH)−4 determined from the equations of Hansson (1972, Ph.D. Thesis, University of Göteborg, Sweden) and Lyman (1957, Ph.D. Thesis, University of California, Los Angeles) differ by ±0.01 m-equiv kg−1 for waters with the same salinity and temperature.
Article
Measurements of the quantum yields of chlorophyll fluorescence and CO2 assimilation for a number of plant species exposed to changing light intensity and atmospheric CO2 concentrations and during induction of photosynthesis are used to examine the relationship between fluorescence quenching parameters and the quantum yield of non-cyclic electron transport. Over a wide range of physiological conditions the quantum yield of non-cyclic electron transport was found to be directly proportional to the product of the photochemical fluorescence quenching (qQ) and the efficiency of excitation capture by open Photosystem II (PS II) reaction centres (Fv/Fm). A simple fluorescence parameter, ΔφF/φFm, which is defined by the difference in fluorescence yield at maximal φFm, and steady-state φFs, divided by φFm, can be used routinely to estimate changes in the quantum yield of non-cyclic electron transport. It is demonstrated that both the concentration of open PS II reaction centres and the efficiency of excitation capture by these centres will determine the quantum yield of non-cyclic electron transport in vivo and that deactivation of excitation within PS II complexes by non-photochemical processes must influence the quantum yield of non-cyclic electron transport.
Article
The effects of zinc (Zn) on plant chlorophyll fluorescence were investigated in 10-day-old tomato (Solanum lycopersicum) seedlings subjected for 7 days to a series of zinc (10, 50, 100 and 150μM) applied via the nutrient solution. The chlorophyll fluorescence spectra of leaves were recorded in the spectral region 650-800nm using the spectroscopic technique of ultraviolet light emitting diode induced fluorescence spectroscopy (UV-LED IFS). These spectra have been used to analyze the effect of several doses of zinc on the photosynthetic activities of tomato plants. The fluorescence intensity ratios (FIR) at the two maxima (F(690)/F(735)) of control as well as treated tomato plants were calculated by evaluating curve-fitted parameters using a Gaussian spectral function. The variable chlorophyll fluorescence decrease ratio (R(Fd)) values were determined from the fluorescence induction kinetics curves recorded at 690nm and 735nm. In addition, Zn accumulation in plants, plant growth, photosynthetic pigments content and malondialdehyde level (MDA, an index of lipid peroxidation) were also estimated. The results indicated that the plants treated with 10μM of zinc exhibited better growth, however, higher concentrations of zinc were harmful for plants. Excess Zn induced a decrease in the R(Fd) values, which was associated with a strong decline of the total chlorophylls content and an increase of MDA level. The total chlorophylls content decline could also be followed via an increase of the chlorophyll fluorescence ratio F(690)/F(735).
Article
The rough bark of orchard trees (Malus) around Darmstadt is predominantly covered in red to purple-brown layers (biofilms) of epiphytic terrestrial alga of Trentepohlia umbrina. The smooth bark of forest trees (Fagus sylvatica L. and Acer sp.) in the same area is covered by bright green biofilms composed of the green algae Desmococcus, Apatococcus and Trebouxia, with a few cells of Coccomyxa and 'Chlorella' trebouxioides between them. These algae are desiccation tolerant. After samples of bark with the biofilms were kept in dry air in darkness for various periods of time, potential quantum yield of PSII, F(v)/F(m), recovered during rehydration upon rewetting. The kinetics and degree of recovery depended on the length of time that the algae were kept in dry air in the desiccated state. Recovery was better for green biofilm samples, i.e. quite good even after 80 days of desiccation (F(v)/F(m) = ca. 50% of initial value), than the red samples, where recovery was only adequate up to ca. 30-40 days of desiccation (F(v)/F(m) = ca. 20-55% of initial value). It is concluded that the different bark types constitute different ecophysiological niches that can be occupied by the algae and that can be distinguished by their capacity to recover from desiccation after different times in the dry state.
Article
Chlorophyll fluorescence analysis has become one of the most powerful and widely used techniques available to plant physiologists and ecophysiologists. This review aims to provide an introduction for the novice into the methodology and applications of chlorophyll fluorescence. After a brief introduction into the theoretical background of the technique, the methodology and some of the technical pitfalls that can be encountered are explained. A selection of examples is then used to illustrate the types of information that fluorescence can provide.