集球藻对盐胁迫的生理适应及细胞结构变化

盐胁迫是影响荒漠区土壤藻类生存的重要环境因子。集球藻是一种广泛分布于生物土壤结皮中的球状绿藻, 能够积累红色素(如虾青素)和油滴, 显示出其独特的生理特性和潜在的应用价值。目前对集球藻的生理、细胞结构以及色素积累的研究非常匮乏。以从荒漠生物结皮中分离的一种集球藻为材料, 在实验室条件下研究盐胁迫对集球藻生物量、光合活性、膜脂过氧化产物丙二醛含量、细胞可溶性蛋白质含量和可溶性糖含量以及细胞结构的影响。研究结果表明, 与对照处理相比, 盐胁迫导致集球藻生物量和光合活性的显著降低, 细胞可溶性蛋白和可溶性糖呈现一定的积累。同时盐处理导致集球藻膜脂丙二醛含量大量增加, SOD和CAT 活性升高。研究还表明, 对照处理下细胞结构完整, 细胞器形态清晰, 生长后期有大量脂肪体积累。在盐处理下藻体细胞形态结构出现阶段性破坏特征和脂肪体以及淀粉粒的积累, 此外细胞器结构模糊和消失, 细胞出现质壁分离和空泡化等。研究为更好地揭示集球藻在盐胁迫环境中的生理适应特性、微结构特征以及色素积累机制具有重要的科学意义, 并为该藻的基础和应用研究提供实验资料。  

CHANGES ON CELLULAR STRUCTURES AND PHYSIOLOGICAL ADAPTATION OF PALMELLOCOCCUS SP. SUBJECTED TO SALT STRESS

Salt stress is one of important ecological factors influencing survival of desert soil algae.Palmellococcus Chod.is a kind of green algae widely distribute in biological soil crusts and is able to accumulate red pigment(astaxanthin) and oil drops,and the algae has displayed especial physiological nature and potential value of application.Currently,studies on physiology,cellular structures and pigment accumulations of Palmellococcus sp.were relatively scarce.In this study,Palmellococcus sp.,isolated from desert algal crusts,was selected for experiment material.Physiological effects of salt stress on the algal cells were investigated by measuring biomass(expressed as chlorophyll a),PS Ⅱ activity(Fv/Fm),intracellular production of water-soluble proteins and saccharides,MDA contents as well as the activities of SOD and CAT.The results showed that salt stress resulted in an obvious decrease in biomass and PSⅡ activity of the treated cells compared to the control cells.It also indicated that intracellular production of water-soluble saccharide and water-soluble proteins were all comparatively greater in the treatment cells than the control cells.Moreover,salt stress had a significantly deleterious effect on membrane lipid superoxide as assessed by measurement of MDA content,and SOD and CAT activities also presented obvious increases as compared to the control.At the same time,it showed from this study that cellular structures and morphological characteristics of Palmellococcus sp.were found to keep intact and clear in the control condition,and there was plentiful lipid body accumulation at growth anaphase of the control culture.However,gradual destruction property in cellular structures were observed from Palmellococcus sp.subjected to salt stress,and synchronously starch and lipid body accumulation were also detected in the treated cells.Furthermore,unintelligible cellular structures and disappearance of cellular organs were observed from Palmellococcus sp.under salt treatment,and plasmolysis and vacuolization were appeared in the treated algal cells.The research results maybe provided us some significative findings for better understanding physiological adaptation,morphological changes and pigment accumulation of Palmellococcus sp.when subjected to salt stress environment,and simultaneously provided us many experimental data for further researches and applications about the green algae.