Functional analysis of BmClock, BmCry-α, and BmCry-β, circadian clock genes found in the genome of the silkworm, Bombyx mori

在家蚕EST数据库中发现了果蝇生物钟基因clock（BmClock）的同源基因。测定了BmClock cDNA的核苷酸序列。该基因全长7521 bp，编码585个氨基酸，含有3个保守结构域，即PAS-1和PAS-2。在B区还发现了哺乳动物隐花色素基因的直向同源物（BmCry-α）。mori EST数据库。该cDNA全长4509 bp，编码730个氨基酸。aa序列分别保守与DNA、MTHF和FAD结合的结构域。在EST中还发现了另一种隐花色素样序列，它是果蝇隐花色素基因的直向同源物。cDNA全长为1587 bp。它编码308个氨基酸残基。对脑组织的RT-PCR分析表明，这两种隐色素mRNA都以昼夜节律的方式表达，并且它们的峰值出现在夜间。另一种隐花色素（BmCry-γ）是新近发现的EST。利用基因芯片技术研究了B幼虫脂肪体的昼夜节律。森。我们发现11个基因表达的mRNA在昼夜节律的方式。另一方面，我们还进行了一个多化性品系和一个二化性品系的杂交试验，发现光周期性不仅受伴性基因的调控，而且受常染色体基因的调控。

An orthologue for clock (BmClock), a Drosophila circadian clock gene, was found in the Bombyx mori EST database. The nucleotide sequence of the BmClock cDNA was determined. The full length cDNA was 7521 bp in length and encoded a putative 585 amino acid sequence, which contained three conserved domains, a basic helix-loop-helix, PAS-1, and PAS-2. BmClock mRNA was expressed with circadian rythmicity, and the mRNA peak was observed in the evening.We also found an orthologue (BmCry-α) of mammalian cryptochrome genes in the B. mori EST database. The cDNA was 4509 bp in length and encoded a complete 730-amino acid protein. The aa sequence conserved the domains for binding to DNA, MTHF, and FAD, respectively. Another kind of cryptochrome-like sequence was also found in the ESTs, it was an orthologue of the Drosophila cryptochrome gene. The length of cDNA was 1587 bp. It encoded 308 amino acid residues. RT-PCR analyzes of the brains demonstrated that both two chryptochrome mRNAs are expressed in a circadian fashion, and their peak appeared in the night. Another kind of cryptochrome (BmCry-γ) has just been found i as an EST. Additionally a member of the DNA 6-4 photolyase gene family (including cryptochromes) was found.The cDNA microarray was utilized to find circadian rhythm in the larval fat body of B. mori. We found 11 genes that expressed mRNAs in the circadian fashion. On the other hand, we also did a crossing experiment between a polyvoltine strain and a bivoltine strain, and found that not only sex-linked gene but also autosomal gene(s) regulates the photoperiodism.