Biological Effects Of Se(Ⅳ) & Te(Ⅳ) On Spirulia And Preliminary Research Of Their Mechanism By Spectroscopy

The effects of selenium and tellurium on S. platensis and 5. maximum were investigated at the higher mass concentration group and the lower mass concentration group respectively, and the data were analyzed with statistics. The additive toxicity of selenium and tellurium mixture to 5. platensis was assessed with AI(additive index). An attempt was made to research the mechanism of the biological effects of selenium and tellurium on spirulina at two levels, the intact algal cell level and and the isolated phycocyanin molecular level, by spectroscopy. Some important results were obtained.Firstly, Se(IV) and Te(IV) stimulated slightly the growth of S. platensis and S. maximum at lower mass concentrations, but inhibited the growth of them at higher mass concentrations. The intensity of stimulative effect and inhibitive effect was also related with the culture conditions apart from the mass concentrations. Both Se(IV) and Te(IV) were toxical to spirulina, and the toxicity of Te(IV) to spirulina were heavier than Se(IV). The additive toxicity of Se(IV) and Te(IV) was assessed to be antagonism.Secondly, the absorption spectra for intact algal cells of S.maxima showed that the intensity of typical absorption peak decreased under Te(IV) stress, whereas the fluorescence spectra suggested that the energy transfer of carotenoids increased. The fluorescence spectra of dry algal powder were markedly different from those of intact algal cells, and it suggested that all the three pigments(chlorophyll a , carotenoids and Phycocyanin ) were damaged in dry powder. IR spectra of dry powder between the control set and Te(IV) stress sets had no difference.And thirdly, after C-phycocyanin(A620/A280=3.0, containing little allophycocyanin) was mixed with Se(IV), the spectrum of the mixture solutionunderwent changes and nano red selenium was observed in the solution after 92h. Among the changes of the spectrum, the absorption spectra showed that with the increase of time and the mass concentration of Se(IV), the characteristic absorption peak at 620nm was decreased gradually but the absorption peaks of phycocyanin at 278nm and 347nm were increased gradually. The fluorescence spectra showed that the fluorescence emission peak and two fluorescence excitation peaks all decreased, but the relative fluorescence intensity of excitation peak at 599nm and 629nm was different from control. The information from the spectra of phycocyanin suggested that phycocyanin could be one of the principal target molecules of Se(IV) and the biological effects of Se(IV) on spirulina, in part, could be caused accordingly by the interaction of phycocyanin and Se(IV)...