摘要
过去,动物摄食和沉降被认为是浮游植物死亡的原因。后来人们发现病毒感染以及逆境条件下的主动死亡(或程序化死亡),也是引起浮游植物死亡的重要原因。文章介绍了浮游植物存在细胞程序化死亡的实验证据和半胱氨酰天冬氨酸特异蛋白酶(caspase)在浮游植物细胞程序化死亡中可能起的作用及浮游植物基因组中的caspase直系同源物。程序化死亡是细胞自主死亡的过程,具有坏死的形态和生物化学过程。浮游植物具有一套后生动物caspase的直系同源物蛋白。作者构建了东海原甲藻cDNA文库,其中有两组EST分别与两个细胞程序化死亡的关键蛋白同源,它们分别是半胱氨酰天冬氨酸特异蛋白酶和分裂细胞核抗体。因此作者推断东海原甲藻可能存在细胞程序化死亡过程。尽管已从细胞生物学特征角度,获得了真核微藻程序化死亡的证据,并从基因组序列中预测出和大规模表达序列标签中鉴定出细胞程序化死亡相关蛋白的编码基因,但离全面认识单细胞真核浮游藻程序化死亡的分子机制以及其生态学意义相差甚远。
Until recently, phytoplankton were considered immortal unless sinking into the deep ocean or eaten by predators. Recently, it has become clear that these organisma can either be infected by vimses or undergo programmed cell death （PCD） in response to environmental stress. Here, experimental evidence for PCD in phytoplankton and the role for caspase and caspase orthologues in phytoplankton genomes were introduced. Evidence of PCD in diatoms, dinoflagellate and phytoplankton were found after monitoring physiological responses to nutrient stress. Phytoplankton PCD is a form of autocatalytic cell suicide in which an endogenous biochemical pathway leads to apoptotic-like morphological changes. It is analogous to PCD or apoptosis in multicellular organisms. Caspases, are a unique class of intracellular proteases, which have a central role in metazoan PCD through the cleavage of various essential proteins. Analyses of the whole genome sequences of prokaryotic and eukaryotic phytoplankton have revealed the widespread presence of sequences coding metacaspases. A cDNA library was constructed for aging Prorocentrum donghaiense, one EST group showed significant homology with the encoding genes of cysteine protease （caspase）. We consided that P. donghaiense may undergo programmed cell death （PCD） when subject to environmental stresses.
出处
《生态环境》
CSCD
北大核心
2007年第6期1801-1806,共6页
Ecology and Environmnet
基金
国家自然科学基金项目(40176028)
