Integrin are transmembrane heterodimers composed of α and β subunits,playing an important role in regulating cell proliferation.This study investigates how integrin β functions during embryonic proliferation in Macrocentrus cingulum.Mcitg-β (GenBank accession no.KC784942) was successfully cloned by PCR.It has an open reading frame of 2 526 bp,encodes an 841 amino-residual protein,and contains typical function domains of integrin genes.Alignment results showed that Mcitg-β is a member of insect integrin gene family,and phylogenetic analysis showed that it shares the highest nucleotide sequence identity (up to 76％) with the integrin gene from Bombus impatiens.qRT-PCR results revealed that Mcitg-β was expressed in primary embryos and secondary embryos,especially highly in eggs,but none in morulae.After RNA interference with dsMcitg-β or siMcitg-β in culture medium,the expression of Mcitg-β mRNA and proliferation ability of embryos were decreased.Furthermore,injecting dsMcitg-β into the parasitized larvae of host Ostrinia furncalis decreased the number of wasp' s offsprings in each host larva.These results initially prove that Mcitg-β may play important roles in regulating the proliferation of embryos in M.cingulum.%整合素是由α和β亚基组成的异源二聚体跨膜蛋白,在调控细胞增殖中起重要作用.本实验初步研究了腰带长体茧蜂Macrocentrus cingulum整合素β亚基在胚胎增殖中所起的作用.用PCR方法克隆获得了腰带长体茧蜂整合素β基因Mcitg-β(GenBank登录号为KC784942),其开放读码框全长2 526 bp,编码841个氨基酸,含有整合素基因特有的多个功能域.Mcitg-β与已报道的昆虫整合素基因具有很高的序列相似性,系统发育分析结果表明其与膜翅目的熊蜂Bombus impatiens整合素基因核苷酸序列一致性最高,达76％.定量PCR结果表明Mcitg-β在蜂卵中大量表达,在初级胚胎及二级胚胎细胞中也有表达,但在桑葚胚中没有表达.将dsMcitg-β通过体外浸泡法导入到二级胚胎或体内注射法导入到寄主亚洲玉米螟Ostrinia furnacalis幼虫体内后,可极显著抑制腰带长体茧蜂整合素基因的表达量,降低胚胎增殖能力,并减少出蜂数量.结果初步证明Mcitg-β可能对调节多胚发育的腰带长体茧蜂的胚胎增殖起重要的作用.
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