Nitric oxide (NO) stimulated the activity of plasma membrane H+-ATPase, 5'-nucleotidase, peroxidase, ascorbate peroxidase and glutathione reductase in ultraviolet B (UV-B) irradiated Chlorella pyrenoidosa. It also boosted the activity of nitrogen-metabolism enzymes such as nitrate reductase, nitrite reductase, glutamine synthetase, which were inhibited by UV-B irradiation. The chlorophyll fluorescence ratio (Fv/Fm) of the UV-B irradiated algae and decreased continuously after the cells were transferred to UV-B irradiation. A continuing decrease of the Fv/Fm was observed even after the cells were transferred to photosynthetically active radiation (PAR). After adaptation for 8 h under PAR (after treatment with nitric oxide), Fv/Fm recovered to 55 % of normal levels--without NO the value approached zero. Exogenous NO stopped the decay of chlorophyll and thylakoid membrane in cells exposed to UV-B irradiation. NO plays probably a key role in damage induced by UV-B irradiation in green algae.

• MeSH
• Algal Proteins metabolism   MeSH
• Cell Membrane enzymology   MeSH
• Chlorella physiology   radiation effects   MeSH
• Enzymes metabolism   MeSH
• Nitric Oxide physiology   MeSH
• Second Messenger Systems * MeSH
• Ultraviolet Rays * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Algal Proteins MeSH
• Enzymes MeSH
• Nitric Oxide MeSH

Terrestrial blue-green algae Scytonema millei, Phormidium bohneri and Lyngbya mesotricha survived to 100 % at atmospheric temperatures of 5-36 degrees C and relative humidity 55-100 % in rainy, winter and spring seasons but the survival was 15-25 % in summer when atmospheric temperature reached 48 degrees C and relative humidity was < or =23 %. Microcoleus chthonoplastes maximum survival was =80 % in rainy season followed by a decrease to =1/2 and 1/4 level in winter and spring, respectively; it disappeared in summer but a few cells and/or trichomes enclosed within sheath may be surviving sticking to soil, not evident microscopically, since the population reappeared at the same place with the onset of rain. Terrestrial green alga Rhizoclonium crassipellitum survived only in spring and died at the onset of summer without forming any dormant cell and/or reproductive structure. Only P. bohneri survived better and longer under submerged conditions in liquid medium than air-exposed on moist soil surface in the culture chamber, while the other algae fared almost equally or slightly better air-exposed on moist soil surface (or even on 2 % agarized medium) than when suspended in liquid medium, indicating that air exposure rather than submerged conditions was needed for most of the terrestrial algae to survive. Water stress imposed on growing algae either on high-agar-solid media or in 0.2-0.6 mol/L NaCl liquid media in the culture chamber reduced vegetative survival in all; it resulted in death without any dormant cell remaining. When stored in desiccators over fused CaCl2, M. chthonoplastes died within 1/2 month, R. crassipellitum and L. mesotricha within 1 month, P. bohneri within 1/2 month, and S. millei not even within 1 1/2 month, indicating their survival pattern against atmospheric dryness to be wide; it also explained the M. chthonoplastes absence in summer and S. millei presence throughout the year. At increased atmospheric humidity the desiccation-sensitive algae (e.g., M. chthonoplastes) survived better than a desiccation-resistant alga (here S. millei). All algae survived considerable darkness (S. millei > 1 1/2 month; P. bohneri, M. chthonoplastes and R. crassipellitum >1 month, and L. mesotricha >1/2 month), and low light intensity of 2 and 10 micromol m(-2)s(-1) which explains their prolific growth in shady places. All algae were differently sensitive to wet heat (45 degrees C for 5-40 min) and to UV shock (0.96-3.84 kJ/m2).

• MeSH
• Chlorophyta physiology   radiation effects   MeSH
• Ecosystem * MeSH
• Saline Solution, Hypertonic MeSH
• Seasons MeSH
• Cyanobacteria physiology   radiation effects   MeSH
• Temperature MeSH
• Ultraviolet Rays MeSH
• Humidity MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Saline Solution, Hypertonic MeSH

Euglena ignobilis cells in natural puddle water of pH 7.8, when kept at 21 +/- 2 degrees C and under continuous light (intensity of approximately 30 micromol m(-2) s(-1)) in a culture chamber, decreased their speed of movement from > or = 78000 microm/min (after a 12-h cultivation), to 850-1300 microm/min after 18 h. Simultaneously initiated were changes in morphology from the usual elongated motile forms to round motile ones by curving and contraction. Water stress (2 and 4 % agarized puddle water, puddle water with 0.2-1 mol/L NaCl), temperature shock (< or = 10 degrees C, > or = 30 degrees C), darkness and low-light intensity, UV exposure (0.96-2.88 kJ/m2), pH extremes (< or = 6.5 and > or = 10), presence of 'heavy' metals (1-100 ppm Fe, Cu, Zn, Co, Ni, Hg) or organic substances in puddle water (25-1000 ppm 2,4-D, captan, urea, DDT, thiourea), all these factors rapidly (after 5 to 30 min) decreased the speed of the elongated motile form to < or = 300 microm/min, and induced all morphological changes leading to formation of round motile and round nonmotile forms. These features in the alga (i.e. sudden speed reduction and morphological changes from elongate motile to round motile form) may thus be suggested to be used in assessing water quality.

• MeSH
• Euglena growth & development   physiology   ultrastructure   MeSH
• Hydrogen-Ion Concentration MeSH
• Organic Chemicals pharmacology   MeSH
• Movement * MeSH
• Heat-Shock Response * MeSH
• Temperature MeSH
• Metals, Heavy MeSH
• Water MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Organic Chemicals MeSH
• Metals, Heavy MeSH
• Water MeSH

Urea at 200 ppm (probably serving as a nitrogen source), liquid Bold's basal medium at pH 7.5, temperature of about 22 degrees C and light intensity of about 40 micromol m(-2) s(-1) for 16 h a day induced rapid and/or abundant zoospores formation and zoosporangia dehiscence and favored zoospore liberation, speed and motility time period in the green alga Rhizoclonium hieroglyphicum. However, factors such as water stress (2 and 4 % agarized media, liquid media with 0.2-0.4 mol/L NaCl, 5-60 min blot-dryness of filaments), pH extremes of liquid media (at < or =6.5 and > or =9.5), temperature shock in liquid media (5 and 35 degrees C for > or =5 min), UV exposure (0.96-3.84 kJ/m2), lack of all nutrients from liquid medium (double distilled water), darkness, and presence of "heavy" metals (1-25 ppm Cu, Fe, Zn, Hg, Ni, Co) or organic substances (200-600 ppm captan or DDT, 800 and 1000 ppm 2,4-D, 50 and 400 ppm indole-3-acetic acid (3-IAA), 1000 and 2000 ppm urea, 100 and 200 ppm thiourea) in liquid media decreased and/or delayed at various levels either zoosporangia survival, zoospore formation or zoosporangia dehiscence and/or the rate of zoospore liberation from zoosporangia, zoospore speed and time period of motility in the media or totally inhibited all these processes. 3-IAA at 50 and 400 ppm induced zoosporangial papilla to grow into a tube-like projection of about 30-120 microm in length. Zoosporangial dehiscence rather than zoospore formation or zoosporangia survival, and zoospore motility period rather than zoospore speed are probably more sensitive to various adverse environmental factors. The rate of zoospores liberation from zoosporangium (possibly related directly to some extent on the zoospore number inside) is probably independent of zoospore speed in the medium.

• MeSH
• Chlorophyta drug effects   growth & development   physiology   radiation effects   MeSH
• Hydrogen-Ion Concentration MeSH
• Culture Media MeSH
• Urea pharmacology   MeSH
• Movement MeSH
• Spores drug effects   growth & development   radiation effects   MeSH
• Temperature MeSH
• Metals, Heavy pharmacology   MeSH
• Darkness MeSH
• Ultraviolet Rays MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Culture Media MeSH
• Urea MeSH
• Metals, Heavy MeSH