Abstract: 【Aim】 Mitogen activated protein kinase (MAPK) cascade is one of the important signal transduction pathways in cells. Ras GTPase-activating protein (RasGAP) gene RasGAP and c-Jun N-terminal kinase (JNK) gene JNK are an up-stream gene and a down-stream gene in MAPK pathway, respectively. This study aims to determine the expression profiles of  RasGAP and  JNK  in the desert beetle Microdera punctipennis in response to low temperature. 【Methods】 A full length cDNA of RasGAP from M. punctipennis was cloned. The deduced amino acid sequence was analyzed, and the phylogynetic tree was constructed. The expression profiles of RasGAP and JNK in M. punctipennis exposed to low temperatures were detected by using real-time quantitative PCR. 【Results】 The ORF of RasGAP cDNA from M. punctipennis is 2 523 bp in length, and was named as MpRasGAP(GenBank accession no.: KM677930), encoding a polypeptide of 840 amino acids with the molecular weight of 96.594 kDa. The encoded protein MpRasGAP belongs to the RasGAP super family. Homology analysis showed that MpRasGAP shares 89% amino acid sequence identity with RasGAP from Tribolium castaneum. When M. punctipennis adults were exposed to 4℃ and -4℃ for 1 h, the mRNA levels of MpRasGAP were significantly upregulated as compared with that at room temperature (25℃). When M. punctipennis adults were exposed to 4℃ for 3 h or -4℃ for 1 h, the mRNA levels of MpJNK were also elevated significantly. 【Conclusion】 The results of this study demonstrate that the expression of both  MpRasGAP and MpJNK in M. punctipennis can be induced by low temperature. Our results will help to further study the role of MAPK pathway in the desert insect under low temperature.

Key words: Microdera punctipennis, low temperature stress, Ras GTPase-activating protein (RasGAP), gene cloning, mRNA level, real-time quantitative PCR