Structure and expression analysis of the Cecropin-E gene from the silkworm, Bombyx mori
2008
Hong, S.M.(Kyushu Univ., Fukuoka (Japan)) | Kusakabe, T. | Lee, J.M. | Tatsuke, T. | Kawaguchi, Y. | Kang, M.W. | Kang, S.W. | Kim, K.A. | Nho, S.K.
Cecropins belong to the antibacterial peptides family and are induced after injection of bacteria or their cellwall components. By silkworm cDNA microarray analysis, a novel type of Cecropin family gene was identified as a cDNA up-regulated in early embryo, 1 day after oviposition. The cDNA isolated was 394 bp with 198 ORF translating 65 amino acids, encoding BmCecropin-E (BmCec-E). Using Southern hybridization and genome search analysis, the number of BmCec-E gene was estimated to be at least two per haploid, which consisted of two exons, as in other Cecropin family members. BmCec-E mRNA was expressed transiently 1 day after egg-laying (AEL, germ-band formation stage), and was specifically expressed in the degenerating intestine during the pre-pupal and pupal stages, unlike other Cecropin family genes. Immune challenge analysis showed that BmCec-E gene expression was more strongly induced by Escherichia coli (gram-negative) than by Micrococus luteus (gram-positive), and not by virus injection. By bacterial challenge, expression of BmCec-E mRNA was induced 12 h after injection, and was maintained for 24 h. Expression of BmCec-E after immune challenge was observed strongly in excretory organs, such as hindgut and malphigian, slightly in fat body, skin, and midgut.
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