DNA methylation plays a role in eukaryotes growth and development.In this study,the function of DNA methylation in larval growth of Lepidoptera pest,Spodoptera litura,and model insect,Bombxy mori,was studied.The results showed that the abnormal larvae,which became smaller,of methylation inhibitor (5-Aza-dC)-treated S.litura and B.mori were increased 36％ and 58.8％ comparing to un-treated larvae,respectively;the RNAi of S.litura methyltransferase Dnmt1 reveal the similar result as 5-Aza-dC treatment,the abnormal larvae was increased 35％.qRT-PCR analysis demonstrated the expression of Bmdnmt1 in wing disc,fat body,epidermis and midgut during larval stage,and the highest expression level was found in wing disc;besides,in wing disc and fat body,the Bmdnmt1 mRNA level in early fifth instar was higher than in prepupa.The mRNA levels of lipase and acyl-CoA binding protein,which belonged to lipid metabolism pathway,were analyzed in 5-Aza-dC-treated B.mori larvae using qRT-PCR and showed that the expression of both genes were inhibited by 5-Aza-dC.All data together suggest that DNA methylation involves in the regulation of Lepidoptera larvae growth,lipid metabolism may be one of pathways regulated by DNA methylation.%DNA甲基化是真核生物生长发育过程中基因表达的一种重要调控机制.本研究以鳞翅目农业害虫斜纹夜蛾Spodoptera litura和模式昆虫家蚕Bombyx mori为材料,研究了甲基化对幼虫生长的影响.研究结果表明,注射甲基化抑制剂5-Aza-dC后,不正常斜纹夜蛾比对照增加了36％,家蚕的增加了58.8％,不正常虫的生长发育缓慢、体型变小.斜纹夜蛾DNA甲基转移酶Sldnmt1 RNAi获得了相似的结果,不正常幼虫率比对照增加了35％.检测家蚕Bmdnmt1的mRNA水平,发现Bmdnmt1在5龄期的翅原基、脂肪体、表皮和中肠均有表达,其表达量在翅原基中的为最高;在翅原基和脂肪体中,Bmdnmt1的含量在5龄初期比在预蛹期的要高.初步分析了甲基化抑制剂处理后的家蚕脂肪代谢相关基因的表达,发现脂肪酶和乙酰辅酶A结合蛋白的mRNA水平在注射5-Aza-dC后48 h显著下调.研究结果初步表明了DNA甲基化参与调控了鳞翅目幼虫的生长发育,脂肪代谢可能是DNA甲基化调控的其中一个通路.
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