Genus Oscillatoria Vaucher (Cyanoprokaryota) in Maldah District, West Bengal, India

Genus Oscillatoria Vaucher is the ubiquitous Cyanoprokaryote, growing in almost all habitats in fresh-water ecosystem like bils, dighis, lakes, ponds, wetlands, and marine water system like - salt marshes and pans, estuaries, brackish waters and ocean. It also occurs on inter-tidal rocks, snow and even in cold lakes underneath 5 m of ice pack as well as in thermal springs. During systematic investigations recorded altogether 25 species, 4 variety and 2 forms from Maldah District viz. Oscillatoria acuta Bürhl and Biswas, Oscillatoria agardhii Gomont, Oscillatoria amoena (Kütz.) Gomont, Oscillatoria amphibia C.Agardh ex Gomont, Oscillatoria amphigranulata Goor, Oscillatoria angusta Koppe, Oscillatoria chalybea G.Mertens ex Gomont, Oscillatoria formosa Bory ex Gomont, Oscillatoria formosa f. loktakensis Brühl and Biswas, Oscillatoria geitleriana Elenkin, Oscillatoria geminata Menegh. ex. Gomont, Oscillatoria limnetica Lemmerm., Oscillatoria limosa C.Agardh ex Gomont, Oscillatoria minnesotensis Tilden, Oscillatoria okenii C.Agardh ex Gomont, Oscillatoria ornata var. crassa C.B.Rao, Oscillatoria perornata f. attenuata Skuja, Oscillatoria princeps Vaucher ex Gomont, Oscillatoria prolifica Gomont, Oscillatoria proteus Skuja, Oscillatoria pseudogeminata var. unigranulata Biswas, Oscillatoria quadripunctulata Brühl and Biswas, Oscillatoria raoi DeToni, Oscillatoria redekei Goor, Oscillatoria rubescens DC. ex Gomont, Oscillatoria splendida Grev. ex Gomont, Oscillatoria subbrevis Schmidle, Oscillatoria tenuis C.Agardh ex Gomont, Oscillatoria tenuis var. natans Gomont, Oscillatoria tenuis var. tergestina Rabenh. ex Gomont and Oscillatoria willei N.L.Gardner. However, Oscillatoria subbrevis Schmidle, Oscillatoria tenuis C.Agardh ex Gomont are the most common species followed by Oscillatoria amphigranulata Goor, Oscillatoria acuta Bürhl and Biswas, Oscillatoria amphibia C.Agardh ex Gomont, Oscillatoria amphigranulata Goor in water bodies of Malda District. Oscillatoria redekei Goor is reported new from India.

Dependence of the Flash-Induced Oxygen Evolution Pattern on the Chemically and Far Red Light-Modulated Redox Condition in Cyanobacterial Photosynthetic Electron Transport

Flash-induced photosynthetic oxygen evolution was measured in cells and thylakoid preparations from the coccoid cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 and from the filamentous cyanobacterium Oscillatoria chalybea. The resulting characteristic flash patterns from these cyanobacteria can be chemically altered by addition of exogenously added substances like CCCP, DCPiP and inorganic salts. Potassium chloride, manganese sulfate and calcium chloride affected the sequences by specific increases in the flash yield and/or effects on the transition parameters. Chloride appeared to exert the strongest stimulatory effect on the oxygen yield. In comparison to chloride, both manganese and calcium did not significantly stimulate the flash amplitudes as such, but improved the functioning of the oxygen evolving complex by decreasing the miss parameter α. Particular effects were observed with respect to the time constants of the relaxation kinetics of the first two flash signals Y1/Y2 of the cyanobacterial patterns. In the presence of the investigated chemicals the amplitudes of the first two flash signals (Y2 in particular) were increased and the relaxation kinetics were enhanced so that the time constant became about identical to the conditions of steady state oxygen flash amplitudes. The results provide further evidence against a possible participation of either PS I or respiratory processes to Y1/Y2 of cyanobacterial flash patterns. Dramatic effects were observed when protoplasts from Oscillatoria chalybea or cells from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 were exposed to weak far red background illumination. Under these conditions, Y2 (and to a smaller extent Y1) of otherwise unchanged flash sequences were specifically modified. Y2 was substantially increased and again the relaxation kinetics were accelerated making the signal indistinguishable from a Yss signal. From the mathematical fit of the sequences we conclude that S2 contributes to 10-20% of the S-state distribution (in comparison to 0% in the control). Thus, far red background illumination might represent a valuable means for photosynthetic investigations where high amounts of S2 are required like e.g. EPR measurements. In such experiments the corresponding EPR signals appeared substantially enhanced following far red preillumination (Ahrling and Bader, unpublished observations). Our results clearly show that the ‚controversial results‘ from parts of the literature suggesting the participation of different mechanisms (net oxygen evolution, inhibited uptake processes etc.) are not required to explain the flash-induced oxygen evolution in cyanobacteria: the seemingly ‚incompatible‘ conditions and conformations can be perfectly interconverted by different modulation techniques (chemicals, far red) of the respective redox condition within the water oxidation complex of photosynthesis

Effect of MgCl2 and Phosphatidylglycerol on CaCl2-Mediated Recovery of Oxygen Evolution in a Photosystem II Complex Depleted of the 17 and 24 kDa Extrinsic Proteins

Phosphatidylglycerol (PG) is an anionic lipid of the thylakoid membrane of higher plant chloroplasts. PG was shown previously to stimulate the evolution of oxygen in intact pho­tosystem II (PSII) membranes [Fragata, M., Strzałka, K. and Nénonéné, E. K. (1991) J. Photochem. Photobiol. B: Biol 11, 329-342], In this work, a study was undertaken of the effect of MgCl2 and PG on the CaCl2-mediated recovery of oxygen evolution in a PSII complex depleted of the extrinsic proteins (EP) of molecular masses 17 kDa (EP17) and 24 kDa (EP24), hereunder designated d17.24PSII. This molecular system is structurally close to the PSII core complex of cyanobacteria and is therefore useful in the comparative analysis of PSII-PG relationships in cyanobacteria and the higher plants. This work reveals a new aspect of the thylakoid lipids role in the PSII function, namely the PG effect on intact PSII is observed as well in d17.24PSII. The results show that phosphatidylglycerol has the ability to compensate for the loss of EP17 and EP24 in the PSII complex. That is, PG restores the oxygen evolution in d17.24PSII incubated in the presence of MgCl2 and/or CaCl2 to the levels observed in native PSII. Moreover, the site of H2O degradation in d17.24PSII, including most probably the pool of calcium and chloride ions, would seem to be protected by phosphatidyl­glycerol. This suggests that one of the docking sites of PG in the PSII complex is near EP24, inasmuch as this extrinsic protein participates in the regulation of the affinity of the calcium and chloride ions to the water oxidation site. Furthermore, taking into account that in d17.24PSII the PSII core complex is directly exposed to PG, then the phospholipid effect reported here indicates that phosphatidylglycerol might be a functional effector and mem­brane anchor of the D1 protein in the PSII core complex as was shown recently in the cyanobacterium Oscillatoria chalybea [Kruse, O. and Schmid, G. H. (1995) Z. Naturforsch. 50c, 380-390],

Characterization of Hydrogen Photoevolution in Oscillatoria chalybea Detected by Means of Mass Spectrometry

The filamentous non-heterocystous cyanobacterium Oscillatoria chalybea is capable to photoevolve molecular hydrogen when the cells are flushed to anaerobiosis with nitrogen or argon and exposed to short light flashes or continuous light. The light-induced hydrogen gas exchange of Oscillatoria chalybea has been investigated by direct determination of dynamic changes in the hydrogen partial pressure at m/e=2 in the H/D collector of a mass spectrometric set-up. By means of this technique also the time curves of the light-induced hydrogen gas exchange could be directly recorded. Depending on the chlorophyll concentration in the measuring cell we observed an increasing hydrogen content of the aqueous Oscillatoria suspension i.e. a dark evolution of molecular hydrogen. Upon the onset of light an initial rise of the H 2-signal was observed which was increasingly mixed or followed by a hydrogen uptake. The capability to photoevolve molecular hydrogen was maximal with young cultures and decreased with increasing age. The hydrogen evolution signals require relatively short dark adaptation to get pronounced; few seconds suffice for 2/3 of the hydrogen evolution amplitude. Prolonged dark adaptation maximizes the flash amplitudes. The hydrogen evolu­tion signals do not deactivate by low flash frequency Oscillatoria chalybea evolves molecular hydrogen following growth on nitrogen free or nitrate containing medium. Increase of the oxygen partial pressure of the assays completely abolishes the hydrogen evolution signals with an I50-value of 6 μm.