Expression patterns and organization of the hsp70 genes correlate with thermotolerance in two congener endemic amphipod species (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal
Expression patterns and organization of the hsp70 genes correlate with thermotolerance in two congener endemic amphipod species (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal
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DOI：
10.1111/mec.12136
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发表时间：
2013-03-01
影响因子：
4.9
通讯作者：
Zatsepina, O. G.
中科院分区：
文献类型：
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作者：
Bedulina, D. S.;Evgen'ev, M. B.;Zatsepina, O. G.
研究了贝加湖沿岸特有的两种片足类动物（Eulimnogammarus cyaneus和E. verrucosus）的热休克蛋白70 （hsp70）基因在不同水平上的表达，研究了热休克反应的各个方面，这两种动物在垂直分布和耐热性方面存在显著差异。尽管这两个物种的Hsp70组成水平都很高，但在正常生理条件下（7℃），耐热的蓝芽孢杆菌的Hsp70蛋白基础水平是耐热的蓝芽孢杆菌的5倍，温度升高后的Hsp70诱导水平明显低于热敏的疣孢杆菌。我们从两个物种中分离出hsp70基因并分析了它们的序列。在正常生理条件下，两种物种均检测到胞质Hsp70/Hsc70蛋白的两种同工型，并由两种不同的hsp/ Hsc70家族成员编码。两种Hsp70异构体都是在没有热休克的情况下合成的，只有一种Hsp70异构体是由温度升高引起的。观察到的Hsp70表达模式的差异，包括Hsp70合成的动态和诱导阈值，表明蓝芽孢杆菌（与疣状芽孢杆菌相比）的耐热性增强与Hsp70基因家族复杂的结构和功能重排有关，有利于Hsp70参与适应波动的热条件。该研究揭示了贝加尔湖片脚类动物热适应的分子机制，并首次描述了生活在热差异栖息地的贝加尔湖特有物种的hsp70基因的结构和功能。
We studied various aspects of heat-shock response with special emphasis on the expression of heat-shock protein 70 (hsp70) genes at various levels in two congener species of littoral endemic amphipods (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal which show striking differences in their vertical distribution and thermal tolerance. Although both the species studied demonstrate high constitutive levels of Hsp70, the thermotolerant E. cyaneus exhibited a 5-fold higher basal level of Hsp70 proteins under normal physiological conditions (7 degrees C) and significantly lower induction of Hsp70 after temperature elevation compared with the more thermosensitive E. verrucosus. We isolated the hsp70 genes from both species and analysed their sequences. Two isoforms of the cytosolic Hsp70/Hsc70 proteins were detected in both species under normal physiological conditions and encoded by two distinct hsp/hsc70 family members. While both Hsp70 isoforms were synthesized without heat shock, only one of them was induced by temperature elevation. The observed differences in the Hsp70 expression patterns, including the dynamics of Hsp70 synthesis and threshold of induction, suggest that the increased thermotolerance in E. cyaneus (compared with E. verrucosus) is associated with a complex structural and functional rearrangement of the hsp70 gene family and favoured the involvement of Hsp70 in adaptation to fluctuating thermal conditions. This study provides insights into the molecular mechanisms underlying the thermal adaptation of Baikal amphipods and represents the first report describing the structure and function of the hsp70 genes of endemic Baikal species dwelling in thermally contrasting habitats.