Hamdoun Amro M, Cheney Daniel P, Cherr Gary N
Bodega Marine Laboratory, PO Box 247, Bodega Bay, California 94923, USA.
Biol Bull. 2003 Oct;205(2):160-9. doi: 10.2307/1543236.
Pacific oysters, Crassostrea gigas, living at a range of tidal heights, routinely encounter large seasonal fluctuations in temperature. We demonstrate that the thermal limits of oysters are relatively plastic, and that these limits are correlated with changes in the expression of one family of heat-shock proteins (HSP70). Oysters were cultured in the intertidal zone, at two tidal heights, and monitored for changes in expression of cognate (HSC) and inducible (HSP) heat-shock proteins during the progression from spring through winter. We found that the "control" levels (i.e., prior to laboratory heat shock) of HSC77 and HSC72 are positively correlated with increases in ambient temperature and were significantly higher in August than in January. The elevated level of HSCs during the summer was associated with moderate, 2-3 degrees C, increases in the upper thermal limits for survival. We measured concomitant increases in the threshold temperatures (T(on)) required for induction of HSP70. Total hsp70 mRNA expression reflected the seasonal changes in the expression of inducible but not cognate members of the HSP70 family of proteins. A potential cost of increased T(on) in the summer is that there was no extension of the upper thermal limits for survival (i.e., induction of thermotolerance) after sublethal heat shock at temperatures that were sufficient to induce thermotolerance during the winter months.
生活在不同潮位高度的太平洋牡蛎(Crassostrea gigas)经常会遇到温度的大幅季节性波动。我们证明,牡蛎的热极限具有相对可塑性,并且这些极限与一类热休克蛋白(HSP70)的表达变化相关。将牡蛎养殖在潮间带的两个潮位高度,在从春季到冬季的过程中监测其同源(HSC)和诱导型(HSP)热休克蛋白表达的变化。我们发现,HSC77和HSC72的“对照”水平(即实验室热休克之前)与环境温度的升高呈正相关,并且在8月显著高于1月。夏季HSCs水平的升高与生存的上限温度适度升高2-3摄氏度有关。我们测量了诱导HSP70所需的阈值温度(T(on))的相应升高。总hsp70 mRNA表达反映了HSP70蛋白家族诱导型而非同源成员表达的季节性变化。夏季T(on)升高的一个潜在代价是,在足以在冬季诱导耐热性的温度下进行亚致死热休克后,生存的上限温度没有延长(即耐热性的诱导)。