快速升温后极地甲藻Polarella glacialis的生理响应

PHYSIOLOGICAL RESPONSE OF POLARELLA GLACIALIS,A POLAR DINOFLAGELLATE,TO TEMPERATURE RISES

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(Ribulose bisphosphate carboxylase oxygenase,核酮糖-1,5-二磷酸羧化酶/加氧酶,光合作用C3碳反应中重要的羧化酶、光呼吸中的加氧酶)、PCNA(Proliferating cell nuclear antigen,增殖细胞核抗原)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1.1×105cells.ml-1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(藻株中处于S期的细胞占所有细胞的百分比)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。

Porella glacialis was discovered from the Antarctic land-fast sea ice and Arctic water column. Recently, P. glacialis-like genotypes were found in temperate waters. The dinoflagellate Rubisco and PCNA antibodies detected specific bands of -53 kDa and -55 kDa in P. glacialis. As shown by the gradient temperature experiment, the diel expression of Rubisco protein maintained nearly stable in the 4℃ culture. The diel expression of PCNA closely related with the % S peak. P. glacialis continued to grow after the cell density increased to 1.1 × 105 cells · ml - 1 When the temperature rose up to 15 and 20℃, the dinoflagellate was stressed with fast reducing cell density, al- tered cell cycle, inactive cell division or even stopped, and greatly reduced abundances and altered diel expression patterns of Rubisco and PCNA. The culture was stressed by 20℃ more. However, the cell density of P. glacialis did not quickly decrease when moved to 15℃. And the cell cycle pattern and the reserved expressing rhythm of the indicative proteins indicated possible cell division of a small part of cells. We concluded that as a polar dinoflagel- late, P. glacialis might exist for a long time in the relatively long and gradual process of warming in the polar re- gion. And it was not surprised for the presence of the P. glacialis-like genotypes in temperate waters.