快速升温后极地甲藻Polarella glacialis的生理响应

Polarella glacialis最早发现于南极固定冰和北冰洋水层,最近在温带海域也发现其相关基因。专抗甲藻的Rubisco、PCNA抗体在该藻细胞内各检测到~53 kDa和~55 kDa的特异性条带。对该藻的梯度温度培养实验显示,4℃生长的P. glacialis细胞密度为1.1×105 cells/ml时仍能继续增殖,一天中藻细胞内Rubisco的表达量基本保持恒定,PCNA的表达量峰值与%S峰值相对应,当温度迅速上升至15、20℃时,藻株处于胁迫状态,细胞密度迅速减少,正常的细胞周期被干扰,大多数细胞分裂活动不活跃或停止分裂,Rubisco、PCNA的表达量大幅减少甚至消失,昼夜表达特征改变,其中20℃对藻株的胁迫作用更加显著。15℃培养下的P. glacialis细胞密度并不立即减少,细胞周期与两种指示蛋白表达特征显示仍有部分细胞完成分裂。本研究为该藻的相关基因在温带水域的出现提供了可能的解释,并推测在相对长期渐进的极地增温过程中,P. glacialis可能继续存在。     

Effects of UVB on the expression of proliferating cell nuclear antigen (PCNA) in dinoflagellate Prorocentrum donghaiense Lu

PCNA has been considered as a useful marker for the estimation of growth rates of marine phytoplankton at the species level. Since dinoflagellates are noted for having many prokaryotic features in that they are the only eukaryotes to have permanently condensed chromosomes as well as lacking histones and a nucleosome, the sensitivity to UVB radiation and the validity of PCNA as a maker of growth rate in dinoflagellate need to be evaluated.Prorocentrum donghaiense Lu was investigated to valuate the UVB sensitivity in relation to cellular and molecular aspects of PCNA as a growth indicator.The effects of UVB radiation on PCNA were studied using the methods of western blots technology and whole-cell immunoflurescence with one mono-antibody. UVB changed the cell morphology, halted the growth and increased the cell size, even caused cell death to a certain extent after treatment with UVB radiation in P. donghaiense. Compared with the control, treating the algal cultures in exponential phases with UVB radiation for 24 h caused chromatin release and increases in protein levels of PCNA.