Identification of a putative RNAse III (dicer homolog) gene in silkworm Bombyx mori

Authors

  • K M Ponnuvel Biotechnology Laboratory, Central Sericultural Germplasm Resources Centre PB No 44, Thally Road, Hosur 635 109, India
  • B Mohana Sundari Biotechnology Laboratory, Central Sericultural Germplasm Resources Centre PB No 44, Thally Road, Hosur 635 109, India
  • R Saravana Kumar Biotechnology Laboratory, Central Sericultural Germplasm Resources Centre PB No 44, Thally Road, Hosur 635 109, India
  • R K Sinha Biotechnology Laboratory, Central Sericultural Germplasm Resources Centre PB No 44, Thally Road, Hosur 635 109, India
  • C K Kamble Biotechnology Laboratory, Central Sericultural Germplasm Resources Centre PB No 44, Thally Road, Hosur 635 109, India

Keywords:

Bombyx mori, RNAse III;, dicer, domain

Abstract

Like other invertebrates, silkworms also encounter a problem from microbial infection including
from RNA viruses. In insects, RNA interference acts as a natural anitiviral response to RNA virus
infection. Especially in Drosophila, it is proved that dicer mediated RNA interference directs innate
immunity against RNA viruses. This information prompted us to identify similar RNAse III (dicer) gene
in mulberry silkworm Bombyx mori. The Drosophila dicer gene was BLAST-searched with B. mori
genome and single contig (GenBank accession n° AADK01001038) showed maximum homology with
dicer gene, through which the RNAse III gene sequence was identified in the genome of silkworm B.
mori. The RNAse III domain was present in the three regions with the length of 278 bp, 277 bp and
185 bp in the contig, possibly these three regions form exons. The primers were designed for three B.
mori RNAse III regions and amplified through PCR. The region I was amplified only in pure Mysore
silkworm strain whereas all three regions were amplified in Daizo strain. The PCR product sequences
were translated and showed RNAse III domain with in the amplified product. The predicted B. mori
RNAse III domain had phylogenetic relationship with other insect dicer genes. We presume that this
RNAse III (dicer) would protect B. mori larvae from invading RNA viruses, which exists in the other
insects.

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Published

2007-02-26

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Section

Research Reports