Cloning And Expression Analysis Of The Three Heat-Shock Protein Genes In Eogystia Hippophaecolus Larvae

Eogystia hippophaecolus,a major borer pest of sea buckthorn in China,damages the environment and sea buckthorn industry.It is widely distributed in the Three-North region of China,and its larvae are resistant to low temperatures.To understand the mechanisms underlying cold tolerance,we examined two small heat-shock proteins(sHSPs)and HSP70,which repair misfolded proteins at low temperatures,thus preventing cell damage and improving tolerance.The open reading frame(ORF)of Eh-HSPs was further cloned into prokaryotic cells to test its expression and validity.We screened the transcriptome of E.hippophaecolus for Eh-HSP19.7,Eh-HSP19.9 and Eh-HSP70 homologs,identified a full-length gene,and cloned to obtain the open reading frale.We measured the expression of the Eh-HSPs gene in various tissues in E.hippophaecolus larvae after cold shocked and during cold recovery.Eh-HSPs ORF was inserted into the expression vector pET-30a(+).The recombinant plasmid was transformed into E.coli BL21(DE3)for prokaryotic expression.Finally,we detected whether three heat-shock proteins are correct expressed by western blotting.The results are as follows:1.The complete cDNA open reading frame sequences of 3 HSP genes were successfully obtained,which were 510 bp,540 bp and 1896 bp in length and encoded 169.179 and 631 amino acids,with molecular weights of 19.7 kDa,19.9 kDa and 69.7 kDa.The amino acid sequence of Eh-HSP70 contained three signature sequences(IFDLGGGTFDVSIL、VVLVGGSTRIPKVQS、IDLGTTYS)of the HSP70 family and a C-terminal cytoplasmic character sequence(EEVD).Pylogenic trees demonstrated that Eh-HSPs has high homology with HSPS genes from other insect species.2.Eh-HSPs expression varied across tissues at 25℃,with the highest expression in the midgut.Compared with control conditions,the expression of Eh-HSPs in the cuticle were upregulated after a cold shock of-5℃ for 1 h.The results demonstrated that low temperature stimulation can promote the expression of the three heat-shock protein genes in different tissues,and the cuticle is the most active site of stress response.Under cold stimulation,sHSPs also showed a strong response in the fat body.3.Eh-HSPs expression also increased significantly during the 1 or 2 h periods following recovery from cold shock and subsequently decreased.The results showed that the insects received low-temperature stimuli and then transferred to a higher temperature.The Eh-HSPs were up-regulated,and then the self-regulation restored the expression level under normal growth conditions.This reflected the ability of insects to self-regulate,and Eh-HSPs participated in the recovery process after low temperature stimulation4.Three heat-shock proteins were respectively ligated into the expression vector and transferred into E.coli,and the recombinant protein was successfully induced by IPTG.SDS-PAGE results revealed that Eh-HSPs were expressed in E.coli.The molecular weight of expressed protein was consistent with the predicted molecular weight of three Eh-HSPs.Western-blot analysis of Eh-HSPs using prepared polyclonal antibodies showed that the three Eh-HSPs could be expressed and expressed accurately.