细菌感染对家蚕DNA甲基化与组蛋白乙酰化相关基因表达的影响

【目的】探讨DNA甲基化及组蛋白乙酰化是否参与家蚕 Bombyx mori 免疫反应的调控。【方法】对家蚕与其他生物的DNA甲基转移酶 (DNMT)、组蛋白去乙酰化酶（HDAC）与组蛋白乙酰转移酶（HAT）的蛋白序列进行系统进化分析；利用定量PCR检测家蚕5龄第3天幼虫感染病原菌绿脓杆菌 Pseudomonas aeruginosa 和金黄色葡萄球菌 Staphylococcus aureus 后 BmDNMT 1, BmHDACI-1, BmHDACI-2和 BmHAT 1在家蚕脂肪体组织中的表达变化；给家蚕5龄第2天幼虫注射DNMT, HDAC和HAT抑制剂，观察它们对家蚕感染细菌后的存活率的影响。【结果】系统进化分析显示，BmDNMT1在进化上呈现特殊性，独立于其他昆虫DNMT1的进化，而BmHDACs和BmHAT在进化上相对保守。定量PCR检测表明，在两种细菌感染后，BmDNMT1, BmHDACs 和 BmHAT1 在家蚕幼虫脂肪体中的表达水平均有不同程度的上升。然而，DNMT, HDAC和HAT抑制剂对家蚕幼虫感染细菌后的存活率并无明显影响。【结论】本研究发现感染绿脓杆菌和金黄色葡萄球菌后，家蚕幼虫脂肪体中 BmDNMT1, BmHDACs 和 BmHAT1 的表达水平有不同程度的上调，推测DNA甲基化和组蛋白乙酰化/去乙酰化可能参与家蚕免疫反应的调控。

Expression of DNA methylation and histone acetylation related genes in response to bacterial infection in the silkworm,Bombyx mori

【Aim】 This study aims to investigate whether DNA methylation and histone acetylation are involved in the regulation of immune responses in the silkworm,Bombyx mori. 【Methods】 We performed the phylogenetic analysis of DNA methyltransferase 1 (DNMT1), histone deacetylase (HDAC) I-1, I-2 and histone acetylase 1 (HAT1) from B. mori and other species. We also profiled their mRNA levels after bacterial ( Pseudomonas aeruginosa or Staphylococcus aureus) infection in the fat body of day-3 5th instar larvae. We then investigated the effects of DNMT inhibitor, HDAC inhibitor and HAT inhibitor on the survival of day-2 5th instar larvae after bacterial infection. 【Results】 Phylogenetic analysis showed that BmDNMT1 is particular and separated from the homologs of other insect taxa. BmHDACs and BmHAT1 are evolutionarily conserved. BmDNMT1, BmHDACs and BmHAT 1 in the fat body had higher expression levels after bacterial challenge. However, no obvious effects of DNMT, HDAC and HAT inhibitors on the survival of silkworm larvae after bacterial infection were observed. 【Conclusion】 The expression levels of BmDNMT1, BmHDACs and BmHAT1 in the fat body of B. mori larvae are up-regulated after infection of P. aeruginosa or S. aureus, suggesting that DNA methylation and histone acetylation/deacetylation might be involved in the regulation of immune responses in the silkworm.