Effect Of UV-B On The Morphology, Ultrastructure And Biochemical Constituents Of Antarctic Cyanophyceae-B And Induction Of The Synthesis Of Anti-UV And Anti-Oxidant Bioactive Substances

Ozone depletion over Antarctic has caused UV radiations to increase, especially irradiances at UV-B wavelengths. UV-B radiation does great harm to human and other livings.The microalgae cyanophyceae has existed for 3~4 billion years, while the ozone sphere has formed for only 450 - 500 million years. So cyanophyceae may live well under UV-B radiation. UV-B radiation may affect functions of many plants, it also may induce the synthesis of anti-UV substances of plants, especially of Antarctic Cyanophyceae, which lives well under enhanced UV-B radiation. People have found many bioactive substances in Cyanophyceae-B, and we may find some anti-UV and anti-oxidant substances in Antarctic Cyanophyceae-B .The observations of SEM and TEM shows the Antarctic Cyanophyceae-B changed its morphology and ultrastructure after UV-B radiation. The size of the cells became larger, and the cell wall became thicker. The laminar structure became more visible, and there were more polysaccharide and fat granules. Furthermore, some of the Cyanophyceae-B cells secreting some material to the culture after UV-B radiation. These changes suggested that there might be some bioactive substances in the Antarctic Cyanophyceae-B cells which could resist UV-B radiation.The biochemical compositions and contents show that after UV-B radiation, the protein of the Antarctic Cyanophyceae-B decreased 17%,while the lipid increased 55%, and the sugar increased 78% .The compositions of monosaccharide and amino acid change little, but the fatty acid changes greatly. The pigment composition also changes much. New pigments are found both in the hydrophilic and lipophilic solvent. All these facts show synthesis of new anti-UV active substances.Many researchers find that microalgae may be a new resource of anti-oxidant. By testing the percentage of free radical cleaned, the Antarctic Cyanophyceae can erase free radical obviously. For example, the methanol extract of Antarctic Cyanophyceae-B after UV-B radiation can erase 91. 7% of the free radicals. That shows Antarctic Cyanophyceae may be an important resource of anti-oxidant.