家蚕Fhx/P25蛋白是丝素蛋白的主要成分之一,过去报道只在家蚕后部丝腺特异的转录表达.通过对大规模的家蚕EST序列分析发现,Fhx/P25基因不仅在家蚕后部丝腺高效转录,而且在家蚕幼虫五龄第三天的卵巢组织及其他组织也有转录;分析还发现Fhx/P25基因在丝腺和卵巢组织中有不同的转录起始位点,在卵巢组织中的转录起始位点比在丝腺中的至少要提前115bp左右.用RT-PCR和FQ-PCR进一步验证,以上分析结果均正确.分析还发现Fhx/P25mRNA存在选择性拼接.以上结果表明Fhx/P25基因并不是组织特异转录基因,它的转录表达存在复杂的调控机制,可能还有其他功能.%Fhx/P25 in silkworm, Bombyx mori, one of the main components of silk fibroin, is presumed in previous reports to be expressed exclusively in the posterior silk gland (PSG) of the animal with strict territorial and developmental specificities. On the basis of a large-scale analysis ofthe silkworm EST data, it was found that Fhx/P25 gene is transcribed not only in the posterior silk gland, but in the ovary and in other tissues of the larvae at day 3 of the fifth-instar as well and that this gene has distinct transcription start sites (TSSs) in the posterior silk gland and the ovary. The TSS in the ovary is located about 115 bp upstream sequence of that in the posterior silk gland. Subsequent RT-PCR, FQ-PCR and sequencing have verified the validity of this presumption. In addition, alternative splicing is predicted in pre-mRNA of Fhx/P25 gene and confirmed by RT-PCR. In conclusion, Fhx/P25 gene is not a gene with strictly tissue-specific transcription.Complicated regulation mechanisms may exist for its transcription and expression and it may have other functions to perform.
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