中文摘要：

热激蛋白在昆虫响应环境胁迫中发挥作用,然而在准噶尔盆地的拟步甲科特有种小胸鳖甲Microdera punctipennis幼虫对环境的适应过程中热激蛋白如何发挥作用尚不清楚。本研究利用实时荧光定量PCR（qRTPCR）技术测定了高低温处理后小胸鳖甲各龄幼虫热激蛋白hsp70基因的表达变化,以探讨小胸鳖甲幼虫hsp70对温度胁迫的响应方式。结果显示,在6-7龄幼虫中hsp70基因的表达水平是5龄之前幼虫的3-5倍,表明hsp70具有发育阶段性差异表达;各龄幼虫经42℃高温处理1 h后hsp70基因的表达量都迅速增加并达到高峰,其中2-5龄的响应非常强烈,可达对照的一千至数千倍;冷驯化低温5℃和10℃对不同龄期幼虫hsp70表达的影响有所不同,其中1龄和4龄幼虫对5℃和10℃均有上调响应,且1龄的响应程度远高于4龄;而7龄幼虫的hsp70表达则受5℃抑制,在10℃短时间内受到诱导,长时间则受到抑制;耐寒性测定结果显示,1龄和7龄幼虫无冷驯化现象,而4龄幼虫经过5℃或10℃冷驯化2 h可使其在-10℃的存活率提高25%,表明hsp70基因表达与小胸鳖甲耐寒性无直接相关性。本研究结果将有助于全面认识HSP70在荒漠昆虫环境适应性中的作用机制。

英文摘要：

Heat shock proteins in insects play a role in response to environmental stress. However, for the larvae of Microdera punctipennis, an endemic species in Junggar Basin, how HSPs function in the process of adaptation to desert environment is unexplored. In this study, hsp70 mRNA level in the larvae of M. punctipennis treated with different temperatures was detected by using real -time quantitative PCR （qRT- PCR） to investigate the response of hsp70 gene to temperature stresses. The results showed that hspTO mRNA levels increased 3-5 fold in the 6th --7th instars compared with the smaller instars, suggesting a developmental differential expression of hsp70 in M. punctipennis larvae. The expression of hsp70 in each larva was dramatically increased after treated at 42 ℃ for 1 h. The 2nd -5th larvae exhibited an extreme up - regulation up to a few thousands fold of the control. The influence of cold acclimation temperature （5 ℃ and 10 ℃ ） on the expression of hsp70 varied among the larvae, in that both in the 1 st and the 4th instar hsp70 showed an up - regulation in response to 5 ℃ and 10 ℃ , and the intensity of the up - regulation in the 1st instar was stringer than that in the 4th instar. On the contrary, the expression of hsp70 in the 7th instar was inhibited at 5 ℃ and was stimulated at 10 ℃ for 1 h but inhibited latter. Cold tolerance experiment showed that there was no cold acclimation in the 1 and the 7＇h instar, while the survival rate of the 4th instar at - 10 ℃ was increased by 25% with pretreatment at 5 ℃ or 10 ℃ for 2 h, suggesting that the expression of hspTO gene is not directly related to the cold tolerance of M. punctipnnies larvae. The present results will help to a further comprehension of the mechanism that M. punctipennis adapts to desert environment.