[The effect of phenols on the parameters of chlorophyll fluorescence and reaction of P700 in the green algae Scenedesmus quadricauda].

The effect of phenols, present in drains of the tsellyulozo-paper industry, on photosynthesis of the microalgae Scenedesmus quadricauda has been studied. The analysis of induction curves of the slowed-down fluorescence and light curves of non-photochemical quenching of chlorophyll fluorescence of microalgae Scenedesmus quadricauda is carried out. It was observed that energization of photosynthetic membranes was inhibited at low concentration of phenol and pyrocatechin (0.1 mM). At higher concentrations phenol and pyrocatechin inhibited electron transport in FSII and increased a share of QB not restoring centers. As a result of it the rate of P700 pigment regeneration slowed down. The results obtained indicate that parameters of induction curves of the fast and slowed-down fluorescence can be used for detecting phenol and pyrocatechin in the environment at early stages of toxic effects.

[Early effect of sodium pentachlorophenate on photosynthetic activity of the alga Chlorella pyrenoidosa Chick S-39].

Early effects of 0.0001-10 mM sodium pentachlorophenate (PCP-Na) on the green alga Chlorella pyrenoidosa Chick. S-39 involves a rapid (within 1-2 min) decrease in the light-induced oxygen evolution by algal cells. The suppressed relative yield of variable chlorophyll fluorescence in C. pyrenoidosa in the presence of high PCP-Na concentrations and its dynamics provide evidence for rapid inactivation of photosystem 2, which is not observed at low concentrations of the toxicant. An analysis of the induction curve of delayed chlorophyll fluorescence in algal cells suggests that PCP-Na at low concentrations disturbs the coupling of electron transport and phosphorylation, whereas at high concentrations it inhibits electron transport and decreases the energy potential of photosynthetic membranes. The early toxic effect of PCP-Na is responsible for subsequent impairment of C. pyrenoidosa productivity.

[Extracellular carbohydrates and polysaccharides of the algae Chlorella pyrenoidosa Chick S-39]. / Vnekletochnye uglevody i polisakharidy vodorosli Chlorella pyrenoidosa Chick S-39.

In the growing culture of the thermophilic alga Chlorella pyrenoidosa Chick S-39, the amount of extracellular carbohydrates in the medium reached 5-17% of their content in the cells and 20-40% of the total content of extracellular organic matter. Experiments with the enrichment and synchronous algal cultures showed that the accumulation of extracellular carbohydrates and polysaccharides in the media occurred due to their release from the cells, rather than to cell lysis, and depended on cell photosynthetic activity and reproduction. Chromatographic determination of free sugars revealed the presence of saccharose, glucose, and fructose in the culture medium. Extracellular carbohydrates in C. pyrenoidosa cultures were represented mainly by water-soluble polysaccharides containing galactose, mannose, arabinose, xylose, ribose, fucose, and rhamnose.

[Early toxic effect of zinc, cobalt, and cadmium on photosynthetic activity of green alga Chlorella pyrenoidosa Chick S-39]. / Rannie éffekty toksicheskogo deistviia tsinka, kobal'ta, kadmiia na fotosinteticheskuiu aktivnost' vodorosli Chlorella pyrenoidosa Chick S-39.

Early toxic effects of heavy metals (HMs) Zn, Co, and Cd in concentration from 0.01 to 100 mM on photosynthetic activity of the green alga Chlorella pyrenoidosa Chick S-39 were studied. The early effect of HMs was manifested as a rapid (0.5-2 h) reduction of photoinduced oxygen release by the algal cells. The suppressed relative yield of variable chlorophyll fluorescence ratio (Fv/Fm) by the metals as well as its dynamics in C. pyrenoidosa demonstrated rapid inactivation of photosystem II (PS II). Analysis of the induction curve of delayed chlorophyll fluorescence in Chlorella cells suggested that the early toxic effects of the tested concentrations of Zn, Co, and Cd included both reduced electron transport in PS II and decreased photosynthetic membrane energization. Hence, the early toxic effect of Zn, Co, and Cd was primarily related to the decreased efficiency of the light reactions of photosynthesis which further reduced the alga productivity later.