Stichococcus Bacillaris Research Articles

Primary bioreceptivity: A comparative study of different Portuguese lithotypes

The current condition of many historical monuments clearly reveals that they are not immune to “weathering” factors such as biological decay or biodeterioration. In the present study, Portuguese lithotype samples were inoculated in the laboratory with the microalga Stichococcus bacillaris and the cyanobacterium Gloeocapsa alpina in order to study their primary bioreceptivity and to establish an index of bioreceptivity. The types of building stones used were Ançã and Lioz limestone, Portalegre granite and Vila Viçosa white marble, which are materials renowned in Portuguese architecture. Microbial growth, including the area of the stone surface covered, was evaluated by visual examination and measurement of in vivo chlorophyll a fluorescence using a spectrofluorometer fitted with a fibre-optic accessory. It was possible to verify that 4 months after inoculation, colonization had led to development of biofilms similar to those occurring on stone monuments located outdoors. The results showed that Ançã limestone had the highest primary bioreceptivity, followed by Lioz limestone, with Portalegre granite being weakly colonized or not colonized at all. White marble was not taken into account for the bioreceptivity index, since ANOVA results of microbial growth showed greater internal variance among replicates than between these and the other lithotypes.

Solar UV-B radiation, associated with ozone depletion, inhibits the Antarctic terrestrial microalga, Stichococcus bacillaris

This study shows that increased UV-B arising from stratospheric ozone depletion over Antarctica reduced cell viability and the maximum quantum yield of photochemistry (Fv/Fm) in a unicellular terrestrial microalga, Stichococcus bacillaris. In the UV waveband, rates of Fv/Fm decline increased with decreasing wavelength. Photosynthetically active radiation (PAR) also reduced Fv/Fm, though less than UV radiation. Further experiments under different ozone column thicknesses showed a significantly greater decline in cell viability and Fv/Fm under ozone depletion compared with non-depleted conditions. The inhibitory effects of ambient solar radiation suggest that S. bacillaris is unlikely to inhabit soil surfaces, but colonises shaded areas beneath soil surface particles. During periods of ozone depletion, increases in the ratio of UV-B:PAR may reduce the thickness of the sub-surface zone where light conditions are suitable for colonisation by this alga.

Origin and evolution of Kinesin-like calmodulin-binding protein.

Kinesin-like calmodulin-binding protein (KCBP), a member of the Kinesin-14 family, is a C-terminal microtubule motor with three unique domains including a myosin tail homology region 4 (MyTH4), a talin-like domain, and a calmodulin-binding domain (CBD). The MyTH4 and talin-like domains (found in some myosins) are not found in other reported kinesins. A calmodulin-binding kinesin called kinesin-C (SpKinC) isolated from sea urchin (Strongylocentrotus purpuratus) is the only reported kinesin with a CBD. Analysis of the completed genomes of Homo sapiens, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and a red alga (Cyanidioschyzon merolae 10D) did not reveal the presence of a KCBP. This prompted us to look at the origin of KCBP and its relationship to SpKinC. To address this, we isolated KCBP from a gymnosperm, Picea abies, and a green alga, Stichococcus bacillaris. In addition, database searches resulted in identification of KCBP in another green alga, Chlamydomonas reinhardtii, and several flowering plants. Gene tree analysis revealed that the motor domain of KCBPs belongs to a clade within the Kinesin-14 (C-terminal motors) family. Only land plants and green algae have a kinesin with the MyTH4 and talin-like domains of KCBP. Further, our analysis indicates that KCBP is highly conserved in green algae and land plants. SpKinC from sea urchin, which has the motor domain similar to KCBP and contains a CBD, lacks the MyTH4 and talin-like regions. Our analysis indicates that the KCBPs, SpKinC, and a subset of the kinesin-like proteins are all more closely related to one another than they are to any other kinesins, but that either KCBP gained the MyTH4 and talin-like domains or SpKinC lost them.

Arsenic availability, toxicity and direct role of GSH and phytochelatins in As detoxification in the green alga Stichococcus bacillaris

Accumulation and toxicity of inorganic arsenic forms As(III) and As(V) to the green microalga Stichococcus bacillaris depended on environmental variables. pH of exposure and to a lesser extent elevated concentrations of humic acid, chloride and orthophosphate ions affected arsenic accumulation and its toxicity. As(V) was more toxic than As(III), especially at the near neutral pH 6.8. Intracellular As(V) uptake by algal cells was greater at pH 6.8 than at 8.2. In response to As(III) and As(V) the alga produced phytochelatins (PC 2–3), but at As(V) exposure, their levels in cells were higher than with As(III), suggesting higher As(V) than As(III) availability and uptake. Arsenic in algal cells occurred in various complexes with non-protein SH groups. Some of these complexes dissociated under acidic conditions, but others were able to dissociate only at an alkaline pH. The former consisted of SH groups of phytochelatins. Those dissociating at an alkaline pH involved SH groups from both glutathione (GSH) and phytochelatins (PC) or their derivatives. In the predominant acid-stable mixed As–SH complex, the ratio of SH (PC 2) to SH (GSH) was 2:1, which suggests that one molecule of PC 2 (containing two SH groups) together with one molecule of GSH were involved in intracellular complexation of each As atom. This is the first demonstration of GSH involvement in arsenic complexation, in vivo. The intracellular concentration of As was greater than that of non-protein SH groups which suggests that not all the arsenic in algal cells was complexed and detoxified by thiol groups.

Differing preferences of Antarctic soil nematodes for microbial prey

We tested the preferences of three nematode taxa, Geomonhystera villosa, Plectus spp. and Teratocephalus spp., extracted from moss at Signy Island in the Maritime Antarctic, for two microalgae, three microfungi and six heterotrophic bacteria, each also from soils at Signy Island. Choice test experiments on water agar medium, in which nematodes were enumerated in wells containing microbes at 24 and 48 h, indicated that there were differing preferences between nematodes for distinct prey. G. villosa was significantly attracted to the alga Chlorella cf. minutissima and the fungus Mortierella hyalina, and was more attracted to all algae and fungi than either of the other two nematodes. Both G. villosa and Teratocephalus spp. were attracted to an actinobacterium. Plectus spp. were significantly attracted to the alga Stichococcus bacillaris and bacteria with close taxonomic affinities to Arthrobacter, Pseudomonas and Polaromonas. Experiments using 0.5 μm diameter fluorescent beads indicated significantly increased ingestion by nematodes in the presence of each of these microbes compared with controls, except by Plectus spp. in the presence of S. bacillaris. We conclude that complex trophic interactions may occur in apparently simple Antarctic soil food webs.

Biological Soil Crust and Vascular Plant Communities in a Sand Savanna of Northwestern Ohio

NEHER, D. A., T. L. WALTERS, E. TRAMER, T. R. WEICHT, R. M. VELUCI, K. SAIYA-CORK (Department of Earth, Ecological and Environmental Sciences, University of Toledo, Toledo, OH 43606) S. WILL-WOLF (Department of Botany, University of Wisconsin, 430 Lincoln Drive, Madison, WI 53706-1381), J. TOPPIN, J. TRAUB (Whitehouse, Ohio 43571-9803) AND JOHANSEN, J. R (Department of Biology, John Carroll University, University Heights, Ohio 44118). Biological soil crust and plant communities in a sand savanna of northwestern Ohio. J. Torrey Bot. Soc. 130:244-252. 2003. A survey of biological crust components (bryophytes, lichens, chlorophyta, bacteria), soil fauna (nematodes, collembolans, mites) and vascular plants was conducted in a dry sand savanna in northwestern Ohio between 1995 and 2001. In soil, six free-living chlorophytes and seven cyanobacteria taxa were identified. Chlorophyta were more abundant than cyanobacteria with Desmococcus olivaeus and Stichococcus bacillaris being the most common species. For bryophytes, the most common species were Polytrichum piliferum and Ceratodon purpureus, and for lichens, Cladonia species. Notably, we found lichen species in the crusts have chlorophytes not cyanobacteria, as their photobionts. Twenty-seven families and 29 genera of nematodes, and four collembolan species were identified in crust and rhizosphere communities. Autotrophic denitrifying bacteria were not detectable with the method employed. The biological crust occurred among a vascular plant community with Robinia pseudoacacia, Rubus flagellaris, Bromus inermis, and Vicia villosa as the most abundant tree, shrub, graminoid, and non-grass herbaceous plants, respectively. To our knowledge, this is the first report of microbial crust community composition in xeric patches of northwestern Ohio. Moreover, our report includes a report of soil nematode or collembolan communities associated with soil biological crust communities.

Molecular characterization of endolithic cyanobacteria inhabiting exposed dolomite in central Switzerland.

The phototrophic microbial community inhabiting exposed dolomite in the alpine Piora Valley (Switzerland) forms a distinct endolithic bilayer that features adjacent red dolomite (exterior) and green dolomite (interior) layers that are c. 0.5-1 mm below the rock surface. Characterization of the community, with an emphasis on cyanobacteria, was conducted with culture-dependent and -independent approaches. Direct microscopy of green dolomite revealed four distinct morphotypes consistent with Chlorophyta genera Chlorella and Stichococcus and the Cyanobacterial genera Nostoc and Calothrix, whereas only Stichococcus and Nostoc were observed in the red dolomite. Enrichment in BG-11 media resulted in the growth of Chlorella and Stichococcus. Denaturing gradient gel electrophoresis (DGGE) analysis of DNA extracted from the enrichment revealed two dominant phylotypes with sequence similarity to Chlorella osrokiniana chloroplast and the cyanobacteria genus Leptolyngbya. 16S rRNA gene-based DGGE analysis of DNA extracted directly from both layers indicated that although both layers harboured phylotypes most similar to the Cyanobacterial genera Nostoc, Chroococcidiopsis, and Microcoleus, and the Chlorophyte Stichococcus bacillaris, the two layers also harboured unique genera such as Scytonema, and Symploca (red, external layer of dolomite) and Chlorella (green, internal layer of dolomite). The unique community structure of each layer suggests a selection process directed by the pressures of the endolithic environment. We conclude that the overall composition of the phototrophic community closely resembles that of endolithic communities located in extreme habitats, suggesting that a cosmopolitan community inhabits this defined niche.

Biotransformation of sinapic acid by the green algae Stichococcus bacillaris 155LTAP and Ankistrodesmus braunii C202.7a

Sinapic acid was bioconverted by the green alga Stichococcus bacillaris into 4-hydroxy-3,5-dimethoxybenzoic acid, 4-hydroxy-3,5-dimethoxybenzaldehyde and 4-hydroxy-3,5-dimethoxybenzylic alcohol. Incubation of sinapic acid in a culture of the alga Ankistrodesmus braunii gave 3,6-dihydroxy-2,4-dimethoxy-7 H-benzocyclohepten-7-one, a new compound formed by bioconversion of thomasidioic acid, the primary oxidative product of sinapic acid.

A preliminary study of the phycological degradation of natural stone masonry.

For many years it has been realised that the weathering of stone is not merely determined by physical and chemical factors but also by biological agents. When the stone in question is a historic building or monument, the damage done constitutes an irretrievable loss of our heritage and history. Laboratory studies have commenced in Paisley to study the effect of photoautotrophs on the major sedimentary rock forming minerals, with a view to expanding this work to study the overall effect of these micro-organisms on heritage masonry. Tests were carried out on Albite, Calcite, Dolomite, Orthoclase, Siderite and Quartz, using axenic cultures of the following: Chlorella vulgaris, Chlorococcum tetrasporum, Scenedesmus obliquus, Oocystis marsonii, Stichococcus bacillaris. The rock chips were immersed in either water or bolds basal media and exposed to a mix of the micro-organisms listed above and then tested weekly for their pH, fortnightly for the waters chemical composition using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and visually utilising the university's SEM facilities. Work so far has revealed biologically mediated etching of minerals, a well-defined pH profile over a period of 90 days, as well as a variety of elemental release patterns for the different minerals.

Phylogenetic relationships of green algae assigned to the genus Planophila (Chlorophyta): evidence from 18S rDNA sequence data and ultrastructure

Phylogenetic analyses, based upon nuclear small-subunit ribosomal RNA gene sequences, of four ‘chlorosarcinoid’ species referred to Planophila Gerneck show that the genus is polyphyletic. The type species, P. laetevirens Gerneck, is closely related to species in the Ulotrichales, Ulvophyceae. The monotypic sarcinoid genus Pseudendocloniopsis is the closest relative of Planophila; the two genera represent the addition of a new morphological type to the Ulotrichales. Planophila microcystis (Dangeard) Kornmann & Sahling forms a clade at the base of the Ulvophyceae with Oltmannsiellopsis, and thus belongs to the Oltmannsiellopsidales. This result is also supported by the Oltmannsiellopsis-like ultrastructure of P. microcystis zoospores. Planophila sp. B from Antarctica, which has Trebouxia-like pyrenoid structure, is a trebouxiophyte closely related to Chlorella-like unicellular coccoids, Stichococcus bacillaris and Prasiola species. This is the first robustly supported molecular phylogenetic analysis that places Prasiola in the Trebouxiophyceae. As shown previously, P. terrestris Groover & Hofstetter belongs to the Chaetopeltidales, Chlorophyceae. Dangemannia gen. nov. (type species : D. microcystis (Dangeard) comb. nov.), Floydiella gen. nov. (type species : F. terrestris (Groover & Hofstetter) comb. nov.) and Pabia gen. nov. (type: P. signiensis sp. nov.) are proposed.

FERRIC CHELATE REDUCTASE ACTIVITY AS AFFECTED BY THE IRON-LIMITED GROWTH RATE IN FOUR SPECIES OF UNICELLULAR GREEN ALGAE (CHLOROPHYTA)1

Four species of green algae (Chlorella kessleri Fott et Novakova, Chlorococcum macrostigmatum Starr, Haematococcus lacustris [Girod-Chantrans] Rostaf., Stichococcus bacillaris Nag.) were grown in iron-limited chemostats and under phosphate limitation and iron (nutrient) sufficiency. For all four species, steady-state culture density declined with decreasing degree of iron limitation (increasing iron-limited growth rate), whereas chl per cell or biovolume increased. Plasma membrane ferric chelate reductase activity was enhanced by iron limitation in all species and suppressed by phosphate limitation and iron sufficiency. These results confirm previous work that C. kessleri uses a reductive mechanism of iron acquisition and also suggest that the other three species use the same mechanism. Although imposition of iron limitation led to enhanced activities of ferric chelate reductase in all species, the relationship between ferric chelate reductase activity and degree of iron limitation varied. Ferric chelate reductase activity in C. macrostigmatum and S. bacillaris was an inverse function of the degree of iron limitation, with the most rapidly growing iron-limited cells exhibiting the highest ferric chelate reductase activity. In contrast, ferric chelate reductase activity was only weakly affected by the degree of iron limitation in C. kessleri and H. lacustris. Calculation of ferric reductase activity per unit chl allowed a clear differentiation between iron-limited and iron-sufficient cells. The possible extension of the ferric chelate reductase assay to investigate the absence or presence of iron limitation in natural waters may be feasible, but it is unlikely that the assay could be used to estimate the degree of iron limitation.

Correlations between toxic Pb effects and production of Pb-induced thiol peptides in the microalga Stichococcus bacillaris

Comparing Pb toxicity to the green alga Stichococcus bacillaris and production of Pb-induced thiol peptides in 24-h exposed cells made it possible to show the level of these peptides to reflect Pb availability to algal cells. LC-ESI/MS analysis of these peptides confirmed that they are phytochelatins PC 2–PC 4 and their des-Gly derivatives. Studies were carried out at environmentally relevant pH values (5–8.5) and various concentrations of hardness cations (Ca, Mg) and orthophosphate: (0–0.1mM), chloride (0–100 mM), citrate (0–1 mM), and humic acids (0–10 mg/l). It has been stated, on the basis of the level of Pb-induced thiol peptides, that Pb availability to algae changed significantly within the range of the pH values studied, and was limited in the presence of calcium and of some complexing ligands like orthophosphate, chloride and citrate; it did not decrease in the presence of magnesium or humic acid.

Soil algae from marlstone-substratum based biotopes in the Nature park Džbán (Central Bohemia, Czech Republic) with special attention to the natural treeless localities

The soil algal species composition of some marlstone-substratum based biotopes of Džban region (Central Bohemia, Czech Republic) was investigated. A total of 54 species representing 42 genera were recovered. Chlorophytes were the most abundant group in all investigated sites. The most common green algal species encountered were Mychonastes homosphaera, Stichococcus bacillaris and Klebsormidium flaccidum. Other frequently occuring species were the cyanophytes Nostoc commune and Phormidium autumnale f. autumnale and diatoms Pinnularia borealis and Nitzschia palea. The investigated sites were compared according to their soil algal floras, The natural treeless localities share similar soil algal synusiae with some typical non-forest features - higher frequency of filamentous cyanophytes and diatomes, occurrence of some desmids. The species list from an investigated secondary meadow is dominated by chlorococcal algae with lower occurrence of other groups. This could be determined by lower pH of the soil from this locality The beech dominated forest locality shares some features typical for temperate forests - lower species richness, common occurrence of green flagellates and unicells, low occurrence of cyanophytes.

THE POSSIBLE DEMI-LICHENIZATION OF THE BASIDIOCARPS OFTRAMETES VERSICOLOR(L.:FRIES) PILAT (POLYPORACEAE)

Five species of epiphytes were found associated with the basidiocarps of the wood-rotting fungus, T. versicolor. Four algae were identified, Hormidium sp., Stichococcus bacillaris, Chlorococcum sp., and Trebouxia sp., as well as one species of bacteria, Azotobacter chroococcum. Azotobacter is a nitrogen-fixing bacterium often associated with lichens, and may be a significant source of nitrogen for T. versicolor. Trebouxia, a genus of lichenized algae that is rarely found free living, is the most common epiphyte. Ultrastructural investigation of the generative hyphae of the upper surface of the basidiocarp reveals the presence of concentric bodies, which are cellular organelles primarily found in lichens. The common occurrence of Trebouxia and Azotobacter as epiphytes, and the occurrence of concentric bodies, suggest that the basidiocarps of T. versicolor have the potential to be lichenized.

Relationships between acid-soluble thiol peptides and accumulated Pb in the green alga Stichococcus bacillaris

Stichococcus bacillaris, an ubiquitous green microalga accumulated inorganic lead (Pb) from aqueous solutions extra- and intracellularly. In response to Pb uptake acid-soluble thiol peptides (glutathione — GSH and phytochelatins — PC) were synthesized. The proportion of the intracellular Pb uptake by algal cells was low and comprised only 3–6% of the total metal sorption. The intracellular uptake was dependent on external Pb concentration, time of metal exposure and cell metabolism. Pb accumulation in alga was determined by means of 210Pb radiometry. Reduced GSH and PC were determined in algal cells using HPLC with the post-column derivatization with Ellman’s reagent. Within the studied concentration range 0.1–20 μM, inorganic lead caused a significant production of induced thiol peptides: PC ( n=2–4) and some other unidentified oligopeptides, probably (GluCys) n. The time of appearance and the concentration of individual oligomers of phytochelatins were dependent on the external Pb concentration and time of metal exposure. In algal cells exposed to Pb, significant changes in the GSH level accompanying the formation of the induced thiol peptides were also observed. The GSH level decreased in the cells exposed to the lower (up to 10 μM) studied Pb concentrations or increased in the cells treated with higher (20 μM) Pb concentrations. The thiol groups originated from induced peptides (mainly phytochelatins) followed a stoichiometric relationship 2:1 to the intracellular Pb amounts, however, only at the lowest studied external concentration (0.1 μM). At higher concentrations (up to 2.5 μM), intracellular Pb concentration was equal or even exceeded (at Pb>2.5 μM) two to three times the level of induced thiols. S. bacillaris accumulated intracellularly by 46% more Pb in light than in dark and the level of induced thiol peptides was significantly higher in the cells exposed to Pb under illumination. The rapid formation of these peptides in S. bacillaris in response to Pb, and their elimination (by about 90%) when algae were placed into the Pb-free solution reveal a tight regulation of GSH and phytochelatin pools in the algal cells exposed to toxic metals. The obtained results suggest that both PCs and GSH are the primary line of defence against the Pb toxicity. Additionally, the induced thiol peptides in S. bacillaris could be a good indicator of intracellular Pb availability and stress at the metal concentrations found in polluted fresh waters.

Endolithic algae and cyanobacteria from cliffs of the Niagara Escarpment, Ontario, Canada

A comprehensive survey for endolithic organisms was undertaken to evaluate the distribution of endolithic algae and cyanobacteria in the structure of ancient cliff ecosystems of the Niagara Escarpment. Rocks were collected at 12 sites along the escarpment. Three rock samples were collected from each of five transects for a total of 180 rock samples. Cryptoendolithic or chasmoendolithic organisms were extracted from freshly cleaved faces under laboratory conditions, and attempts were made to culture, grow, and identify these organisms. Cultures of cryptoendolithic organisms were successfully obtained from between 6.7 and 40% of the culture plates from any one site, whereas chasmoendolithic organisms were obtained from 98% of the attempts. Twenty-two taxa were found, including some Cyanophyta that were present at most sites (Chlorogloea) and others that were found rarely (Schizothrix). Cyanophytes were more common at northern sites than southern sites. Among the Chlorophyta, Stichococcus bacillaris was ubiquitous, but Stichococcus exiguus was restricted to one site. The chlorophytes were evenly found along the Escarpment. No geographical trends were obvious among the Xanthophyceae, but some taxa such as Chloridella neglecta were common and others such as Ellipsoidion stichococcoides were not. These results suggest that endolithic organisms within the rocky limestone cliffs of the Niagara Escarpment are not uniform in abundance or species composition. Consequently, management plans intended to maintain microbial species diversity in the face of different patterns of land use and environmental pollution may have to be location-specific along the escarpment.Key words: terrestrial algae, cryptoendolithic organisms, cliffs, Niagara Escarpment.

Effect of external pH on inorganic carbon assimilation in unicellular marine green algae

SUMMARY Carbonic anhydrase (CA) induction has been studied in three marine green algae under acidic (pH 4.5) or alkaline (pH 8.0) conditions. An inhibition of the induction of the external CA in acidic conditions, similar to that observed in some freshwater green algae, could be observed in only Chlorella saccharophila. In the two other species, Chlorococcum littorale and Stichococcus bacillaris, no significant difference in CA induction was found under two pH conditions. The exact function of the external CA of C. saccharophila remains unclear, since cells grown under acidic conditions (under which this enzyme is repressed) possess the same abilities to use inorganic carbon (Ci) as alkaline-grown cells. Internal pH values were not modified by the pH of the medium used to cultivate C. saccharophila. Regardless of the growth conditions, activities related to carbon fixation, that is, photosynthetic oxygen evolution, Ci uptake and assimilation were enhanced when the measurements were performed at acidic pH. This indicates that this marine alga is able to use CO2 more efficiently than HCO3−. No evidence could be found for a specific Ci uptake and assimilation system in the acid-grown cells.

Selection and sensitivity comparisons of algal species for toxicity testing

The sensitivity of 7 algal species representing the green and blue green algae was evaluated using EC 50 values from the toxicity tests on 3 metal compounds (K 2Cr 2O 7, CuSO 4·5H 2O, ZnSO 4 and 3 formulated products of herbicides (oxyfluorphene, pendimethaline, atrazine). The growth inhibition tests were conducted in microplates. The variability in sensitivity was as high as 5 orders of magnitude (oxyfluorphene). The principal component analysis separated the cyanobacterial strain ( Synechococcus leopoliensis) from the rest of algae representing Chlorophyta. The green algae were divided into two groups: first group with minute species ( Chlorella kessleri and Stichococcus bacillaris) tolerant to herbicides and second group with the most sensitive species: Raphidocelis subcapitata (commonly known under synoym Selenastrum capricornutum), Scenedesmus quadricauda, Scenedesmus subspicatus and Chlamydomonas reinhardtii). The differences in sensitivity among the species of the second group were not distinctive. Therefore, any of these species, because of their similar sensitivity, can be recommended as test organisms in the single algal assays. However, toxicity results showed that none of these species can represent all the phylogenetic (taxonomic) groups of algae.

Effect of extremely high-CO 2 stress on energy distribution between photosystem I and photosystem II in a ‘high-CO 2’ tolerant green alga, Chlorococcum littorale and the intolerant green alga Stichococcus bacillaris

A green alga, Chlorococcum littorale, has a tolerance to extremely high-CO 2 conditions (Kodama et al., J. Marine Biotech. 1 (1993) 21–25). In order to elucidate the mechanism underlying the resistance to such high CO 2 levels, we compared the changes in excitation energy ditribution between photosystem I (PS 1) and photosystem II (PS II) by 77 K fluorescence in cells of the high CO 2-resistant C. littorale and the non-resistant Stichococcus bacillaris. Immediately after the cell are transferred from air to 40% CO 2, the F 714/ F 687 ratio derived from 77 K fluorescence increases in C. littorale cells, suggesting an increase of transition from state 1 to state 2. During this period, more than 80% of plastoquinone A is in the reduced form and the activity of PS I increass. Eventually the F 714/ F 687 ratio, the concentration of reduced plastoquinone A and PS I activity decrease. However, no significant increase of F 714/ F 687 ratio is observed after the transfer of S. bacillaris cells from air to 40% CO 2. The level of reduced plastoquinone A in S. bacillaris gradually increases and the activity of PS I does not show a large change. During the transient period, the level of the D1 protein is approximately constant in C. littorale cells, but is lowered in S. bacillaris. These results suggest that, under extremely high-CO 2 conditions, PS II is protected from photoinhibition by control of the state transition in C. littorale cells, whereas such a protection mechanism does not function in the alga S. bacillaris, non-resistant to CO 2.

Monitoring the cellular response of Stichococcus bacillaris to exposure of several different metals using in vivo 31P NMR and other spectroscopic techniques

The cellular response of a green algae, Stichococcus bacillaris, to sudden exposure of Zn 2+ , Mn 2+ , Cd 2+ , and Cu 2+ was investigated. The algae adsorbed these metal cations on the cell wall initially, and the adsorption equilibrium was established within 3 min. Later, some of the adsorbed metals were either transported inside the algae or released into the solution. The transport of metals inside the algae was demonstrated by their interaction with intracellular polyphosphate. The release of the adsorbed metals into solution is probably the result of detoxification actions. The interaction of copper with algae was found to be unique in many ways (...)