Homeobox genes encode transcriptional factors that play crucial roles in a variety of developmental pathways from unicellular to multicellular eukaryotes. We have identified 102 homeobox genes in the typical insect of Lepidoptera, Bombyx mori, based on the newly assembled genome sequence with 9X coverage. These identified homeobox genes were categorized into nine classes including at least 74 families. The available ESTs and microarray data at present confirmed that more than half of them were expressed during silkworm developmental processes. Orthologs of pb, zen and ftz were newly identified in the Bombyx Hox cluster on chromosome 6. Interestingly, a special group of 12 tandemly duplicated homeobox genes was found located between Bmpb and Bmzen in the Bombyx Hox cluster, suggesting that Hox cluster might have experienced a lineage-specific expansion in the silkworm. A detailed analysis on genome data reveals that a split exists between Bmlab and Bmpb. Our data provide valuable information for future research on the development and evolution of silkworm.

中文翻译：

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家蚕同源异型盒基因的全基因组调查和家蚕Hox簇新结构的鉴定。

同源盒基因编码的转录因子在从单细胞到多细胞真核生物的各种发育途径中起关键作用。根据新组装的基因组序列具有9X的覆盖范围，我们已经在鳞翅目昆虫Bombyx mori的典型昆虫中鉴定出102个同源异型框基因。这些已鉴定的同源盒基因被分为九类，包括至少74个家族。目前可获得的EST和微阵列数据证实，其中有一半以上是在蚕发育过程中表达的。在6号染色体的Bombyx Hox簇中新发现了pb，zen和ftz的直系同源物。有趣的是，在Bombyx Hox簇的Bmpb和Bmzen之间发现了一组特殊的12个串联重复的同源盒基因，这表明Hox簇可能在蚕中经历了特定于谱系的扩展。对基因组数据的详细分析显示，Bmlab和Bmpb之间存在分歧。我们的数据为蚕的发展和进化的未来研究提供了有价值的信息。