家蚕B型清道夫受体基因的鉴定及系统发生与表达分析

Identification,Phylogenetic and Expressional Analyses of Class B Scavenger Receptor Genes in Silkworm,Bombyx mori

B型清道夫受体(SR-B)是清道夫受体超基因家族成员,参与机体的脂类代谢、动脉粥样硬化形成或保护、宿主免疫损害防御、凋亡细胞清除和细胞粘附等重要生命过程。基于家蚕全基因组数据,利用比较基因组学方法,鉴定获得了14个家蚕B型清道夫受体基因,这些基因分布在至少5条染色体上,其内含子的大小从几十到近万个碱基对。系统发生分析表明,14个家蚕B型清道夫受体基因分布在3个类群:第1类群中分布的9个基因和第3类群中分布的3个基因,分别与类群中其它昆虫的同源基因形成明显的直系同源关系;第2类群中分布有2个基因,此类群中不同昆虫的同源基因之间的进化关系较为复杂。EST数据和芯片数据分析表明,多数家蚕B型清道夫受体基因具有转录活性。RT-PCR检测结果显示,有8个家蚕B型清道夫受体基因在5龄第3天幼虫组织中表达,并具有不同的表达模式,推测这些基因可能行使不同的功能。研究结果为进一步诠释家蚕B型清道夫受体基因的功能奠定了基础。

The class B scavenger receptor（SR-B） genes,one of the members of scavenger receptor supergene family,participate in a range of important life processes of organism,such as lipid metabolism,formation or protection of athero-sclerosis,defence of host innate immunity,clearance of apoptotic cells,and cell adhesion etc.Based on data of the silkworm（Bombyx mori） whole genome,we identified 14 putative SR-B genes of silkworm by means of comparative ge-nomic analysis.These genes are distributed on at least 5 chromosomes.The size range of their introns is from dozens of base pairs to nearly ten thousand base pairs.Phylogenetic analysis revealed that 14 SR-B genes of silkworm can be as-signed into 3 groups.9 of them are in group Ⅰ and 3 of them are in group Ⅲ,both of which have apparent orthologous relationships with homologous genes from other insect respectively.Group Ⅱ includes 2 silkworm SR-B genes,of which evolutionary relationships with other insect homologous genes are much complicated.The analytic results using the data of known expressed sequence tags（ESTs） and microarray showed that most of these putative SR-B genes had transcriptional activity.RT-PCR results indicated that 8 SR-B genes of silkworm expressed in the tissues of 3-day-old 5th instar larvae and had different patterns of expression profile,suggesting that these SR-B genes have different functions.These findings form a good basis for further annotating the functions of SR-B genes.