Clark Melody S, Fraser Keiron P P, Peck Lloyd S
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK.
Cell Stress Chaperones. 2008 Spring;13(1):39-49. doi: 10.1007/s12192-008-0014-8. Epub 2008 Feb 7.
The success of any organism depends not only on niche adaptation but also the ability to survive environmental perturbation from homeostasis, a situation generically described as stress. Although species-specific mechanisms to combat "stress" have been described, the production of heat shock proteins (HSPs), such as HSP70, is universally described across all taxa. Members of the HSP70 gene family comprising the constitutive (HSC70) and inducible (HSP70) members, plus GRP78 (glucose-regulated protein, 78 kDa), a related HSP70 family member, were cloned using degenerate polymerase chain reaction (PCR) from two evolutionary divergent Antarctic marine molluscs (Laternula elliptica and Nacella concinna), a bivalve and a gastropod, respectively. The expression of the HSP70 family members was surveyed via quantitative PCR after an acute 2-h heat shock experiment. Both species demonstrated significant up-regulation of HSP70 gene expression in response to increased temperatures. However, the temperature level at which these responses were induced varied with the species (+6-8 degrees C for L. elliptica and +8-10 degrees C for N. concinna) compared to their natural environmental temperature). L. elliptica also showed tissue-specific expression of the genes under study. Previous work on Antarctic fish has shown that they lack the classical heat shock response, with the inducible form of HSP70 being permanently expressed with an expression not further induced under higher temperature regimes. This study shows that this is not the case for other Antarctic animals, with the two molluscs showing an inducible heat shock response, at a level probably set during their temperate evolutionary past.
任何生物体的成功不仅取决于生态位适应，还取决于在体内平衡受到环境扰动（一种通常被称为应激的情况）时的生存能力。尽管已经描述了特定物种对抗“应激”的机制，但热休克蛋白（HSPs）的产生，如HSP70，在所有分类群中都有普遍描述。使用简并聚合酶链反应（PCR）从两种进化上不同的南极海洋软体动物（分别为双壳类的椭圆侧腕水母和腹足类的南极笠贝）中克隆了HSP70基因家族的成员，该家族包括组成型（HSC70）和诱导型（HSP70）成员，以及相关的HSP70家族成员葡萄糖调节蛋白78（GRP78，78 kDa）。在进行急性2小时热休克实验后，通过定量PCR对HSP70家族成员的表达进行了检测。两个物种都表现出随着温度升高HSP70基因表达显著上调。然而，与它们的自然环境温度相比，诱导这些反应的温度水平因物种而异（椭圆侧腕水母为+6 - 8摄氏度，南极笠贝为+8 - 10摄氏度）。椭圆侧腕水母还显示了所研究基因的组织特异性表达。先前对南极鱼类的研究表明，它们缺乏经典的热休克反应，HSP70的诱导型持续表达，在更高温度条件下表达不会进一步诱导。这项研究表明，其他南极动物并非如此，这两种软体动物表现出诱导性热休克反应，其水平可能是在它们温带进化历史中设定的。
