The Effect Of Exogenous Signals On Physiological And Metabolic Process Of Cyanobacteria Under Ultraviolet-B Radiation

Along with the advance of human production and livelihood, more and morechlorofluorocarbons (CFCs) are released into the atmosphere, which making a seriousenvironmental problem by the ozone layer depletion. The direct consequence of the ozonedepletion is the intensity of UV-radiation reaching the earth. There are more and more reportsabout the effect of UV-radiation on the physiological and metabolic process in the scientificfields, which leads researchers to concentrate the studies on the effect of signal substances tothe process between UV-radiation and creatures. In this paper, the effects of hydrogenperoxide (H2O2), nitric oxide (NO) and Spermine (spd) are studied under ultraviolet-Bradiation(UV-B) in gloeocapsa.sp obtained from Qinghai lake. The change of the growth andthe content of barrier material of UV-B were estimated and the ability of antioxidant systemwas also estimated. The microstructure of gloeocapsa.sp is evaluated in the groups ofH2O2.The main findings are as follows:(1)Research shows that, after adding H2O2for0.5mmol/L to the culture ofcyanobacteria under UV-B radiation, the descend degree of cyanobacteria biomass underUV-B stress slowed down and the content of soluble sugar and soluble protein in the body ofcyanobacteria under UV-B stress were increased. Joining the H2O2for0.5mmol/L to theculture of cyanobacteria under UV-B radiation, the microstructure of cyanobacteria underUV-B stress was protedted. After adding H2O2for0.5mmol/L to the culture of cyanobacteriaunder UV-B radiation, the content of the barrier material of the UV-B such as chlorophyll,carotenoids, scyonemin, phycobiliprotein and the mycosporine like amino acids (MAAs) inthe cyanobacteria body under UV-B stress were decreased. After adding H2O2for0.5mmol/Lto the culture of cyanobacteria under UV-B radiation, the activity of catalase (CAT),superoxide dismutase (SOD), the flavonoid and proline content in the cyanobacteria wereincreased and the content of malondialdehyde (MDA) was decreased under UV-B stress. Inconclusion, H2O2can enhance the ability of anti-oxidation system in the cyanobacteria bodyunder the UV-B stress to help the cyanobacteria to resist the UV-B stress.(2)Experimental results shows that, after adding NO donor SNP for0.5mmol/L to theculture of cyanobacteria under UV-B radiation, the descend degree of cyanobacteria biomassunder UV-B slowed down and the content of soluble sugar and barrier material of the UV-Bsuch as chlorophyll, carotenoids, scytonemin, phycobiliprotein and the MAAs in thecyanobacteria body under UV-B stress were increased. Joining the NO for0.5mmol/L to theculture of cyanobacteria under UV-B radiation, the activity of CAT and SOD, the content offlavonoid was increased and the MDA content was reduced in the cyanobacteria body underUV-B stress. It shows that NO can help cyanobacteria resist UV-B stress by stimulating the cyanobacteria body to improve the barrier material content and raising the ability ofantioxidant system.(3)After adding spd for0.1mmol/L to the culture of cyanobacteria under UV-B radiation,the descend degree of cyanobacteria biomass under UV-B slowed down and the content ofsoluble sugar in the cyanobacteria body under UV-B stress went up. Joining the spd for0.1mmol/L to the culture of cyanobacteria under UV-B radiation, the content of the barriermaterial of the UV-B in cyanobacteria such as chlorophyll, carotenoids, phycobiliproteinexcept the scytonemin and MAAs were decreased. After adding spd for0.1mmol/L to theculture of cyanobacteria under UV-B, the activity of CAT and SOD, the content flavonoidand proline were increased and the content of MDA was decreased in the cyanobacteria bodyunder UV-B stress. From the above it shows that spd can ease the UV-B damage from algaeby enhancing the ability of antioxidant system of algae.