Most cited article - PubMed ID 11200670
Effects of increasing doses of UV-B radiation on photosynthesis and motility in Chlamydomonas reinhardtii
The effect of ultraviolet-B radiation (UV-B; 280-320 nm) on induction of nitric oxide was estimated in the suspensions of green alga Chlorella pyrenoidosa with or without the NO scavenger N-acetyl-L-cysteine, and reductants such as 1,4-dithiothreitol, glutathione (reduced form), and ascorbic acid. Exogenously added sodium nitroprusside (NO donor), glutathione, 1,4-dithiothreitol, and ascorbic acid were able to prevent chlorophyll loss mediated by UV-B. Addition of NO to algal suspensions irradiated by UV-B increased the activity of catalase and superoxide dismutase but lowered the activity of phenylalanine ammonia-lyase. UV-B thus appears to be a strong inducer of NO production, exogenously added NO and reductants protecting the green alga against UV-B-induced oxidative damage.
- MeSH
- Acetylcysteine pharmacology MeSH
- Chlorella enzymology metabolism radiation effects MeSH
- Chlorophyll metabolism MeSH
- Dithiothreitol pharmacology MeSH
- Phenylalanine Ammonia-Lyase metabolism MeSH
- Glutathione pharmacology MeSH
- Catalase metabolism MeSH
- Ascorbic Acid pharmacology MeSH
- Nitroprusside pharmacology MeSH
- Nitric Oxide biosynthesis MeSH
- Oxidative Stress drug effects physiology MeSH
- Superoxide Dismutase metabolism MeSH
- Ultraviolet Rays adverse effects MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Acetylcysteine MeSH
- Chlorophyll MeSH
- Dithiothreitol MeSH
- Phenylalanine Ammonia-Lyase MeSH
- Glutathione MeSH
- Catalase MeSH
- Ascorbic Acid MeSH
- Nitroprusside MeSH
- Nitric Oxide MeSH
- Superoxide Dismutase MeSH
Vegetative cells in dried, mucilagenous mass of Gloeocapsa aeruginosa and Aphanothece nidulans, reticulum of Hydrodictyon reticulatum, mucilagenous mass of Chroococcus minor, and filaments of Oedogonium sp. and Scytonema hofmanni died within 1/2, 1/2, 1/2, 1, 3 and 6 h, respectively, while dried vegetative filaments of Phormidium foveolarum retained under similar storage conditions viability for 4 d. P. foveolarum tolerated 1 mol/L NaCl. The resistance to desiccation in P. foveolarum exhibited similar dependence as that to heat or UV light. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced at various levels or altogether inhibited the survival of vegetative parts in all, the cell division in C. minor, G. aeruginosa and A. nidulans, formation of heterocyst and false branch in S. hofmanni, oogonium in Oedogonium sp., and daughter net in H. reticulatum. Heat or UV shock of any level also produced similar effects as that by water stress. P. foveolarum tolerated low light level of 10 and 2 mumol m-2 s-1 and no light longer than the rest of other algae studied. Tolerance of microalgal forms to water, heat or UV stress depends primarily upon cell-wall characteristics or cell-sap osmotic properties rather than their habitats, morphology and prokaryotic or eukaryotic nature.
Dried vegetative filaments of Spirogyra sp., Vaucheria geminata and Nostoc calcicola died within 1/2, 1 and 4 h, respectively; those of Hormidium fluitans, Oscillatoria agardhii and Lyngbya martensiana retained under similar storage conditions viability for 3, 5 and 10 d, respectively. The viability of dried vegetative filaments of L. martensiana, O. agardhii and H. fluitans decreased on storage at 20 degrees C in the dark. L. martensiana and O. agardhii tolerated 0.8 mol/L NaCl. The resistance to desiccation in L. martensiana and O. agardhii exhibited similar dependence as that to frost, to heat and UV light. O. agardhii filaments became slightly broader and their cells developed large number of gas vacuoles when grown in 0.8 mol/L NaCl-containing medium. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced hormogonium formation in L. martensiana and O. agardhii, heterocyst and akinete formation in N. calcicola and fragmentation in H. fluitans; it did not induce conjugation in Spirogyra sp. and formation of reproductive organs in V. geminata. In all studied algae the stress reduced at various levels the survival of vegetative parts. Generally, algal body form and composition rather than habitats seem to decide primarily the level of resistance against various stress conditions.
- MeSH
- Sodium Chloride pharmacology MeSH
- Culture Media MeSH
- Heat-Shock Response * MeSH
- Reproduction physiology MeSH
- Cyanobacteria growth & development physiology MeSH
- Ultraviolet Rays MeSH
- Hot Temperature MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Sodium Chloride MeSH
- Culture Media MeSH
The influence of pH 3-10 on the growth, motility and photosynthesis in Euglena gracilis was demonstrated during a 7-d cultivation. The cells did not survive at pH < 4 and > 8, highest growth rate being detected at pH 7. Motility followed a similar pattern as growth rate. Photosynthetic response curves were shown to be of the same type over the whole pH range. High respiration was characteristic for cells grown at pH 5 and 6, the lowest one at 7. At high and also at low pH more active respiration was found which can be considered as a protective response on proton stress. Respiration was not completely inhibited with potassium cyanide. Photosynthesis was the most effective at pH 6; lower and higher pH decreased photosynthetic efficiency. pH affected more the growth rate than the photosynthesis.
- MeSH
- Euglena gracilis growth & development physiology MeSH
- Photosynthesis * MeSH
- Hydrogen-Ion Concentration MeSH
- Potassium Cyanide MeSH
- Movement MeSH
- Oxygen Consumption MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Potassium Cyanide MeSH
