Novel female-specific splice form of dsx in the silkworm, Bombyx mori
- 329 Downloads
The Bombyx mori doublesex (Bmdsx), a homologue of doublesex of Drosophila, is the bottom most gene of the sex determination cascade. Bmdsx plays a very crucial role in somatic sexual development. Its pre-mRNA sex-specifically splices to generate two splice variants; one encodes female-specific and the other encodes male-specific polypeptides which differ only at their C-termini. The open reading frame of Bmdsx consists of 5 exons, of which exons 3 and 4 are female-specific and are skipped in males. In the present study, we have identified a third splice form of the Bmdsx which is specific only to females and differs from the previously reported Bmdsxf isoform by the presence of 15 bp sequence. This new female splice form is generated as a result of alternative 5′ splice site selection in the third exon adding additional 15 bp sequence in exon 3 which results in alteration of the reading frame leading to incorporation of an early stop codon. Thus the protein encoded by this splice form is 20 aa shorter than the known BmDsxF. Initial results obtained from the study of dsx homologues in Saturniid silkmoths suggest that both the female-specific Dsx proteins are essential for female sexual differentiation. It remains to be seen whether female-specific multiple splice forms of dsx are characteristic feature of only silkmoths or widespread among lepidopterans. The findings that sex determination mechanism is unique in lepidopterans offer an opportunity to develop genetic sexing methods in beneficial as well as economically destructive lepidopteran pests.
KeywordsBombyx mori Doublesex ESTs Splicing SIT
J Nagaraju acknowledges Centre of Excellence grant from the Department of Biotechnology, Government of India. JN Shukla is recipient of the fellowship from Council of Scientific and Industrial Research (CSIR), India.
- Ajimura M, Ken S, Hiroaki A, Toshiki T, Toru S, Mita K (2006) Are the zinc-finger motif genes, z1 and z20, located in the W chromosome involved in the sex-determination of the domesticated silkworm, Bombyx mori? Abstracts from Seventh International Workshop on the Molecular Biology and Genetics of the Lepidoptera J Insect Sci [will be available online http://www.insectscience.org/]
- Bull JJ (1983) Evolution of sex determining mechanisms. Benjamin Cummings Publishing, Menlo ParkGoogle Scholar
- Satish V, Shukla JN, Nagaraju J (2006) CCCH-type zinc finger genes: candidate regulators of sex determination pathway in the silkworm, Bombyx mori. Abstracts from Seventh International Workshop on the Molecular Biology and Genetics of the Lepidoptera J Insect Sci [will be available online http://www.insectscience.org/]
- Shukla JN, Nagaraju J (2010) Two female-specific DSX proteins are encoded by the sex-specific transcripts of dsx, and are required for female sexual differentiation in two wild silkmoth species, Antheraea assama and Antheraea mylitta (Lepidoptera, Saturniidae). Insect Biochem Mol Biol. doi: 10.1016/j.ibmb.2010.06.008 PubMedGoogle Scholar
- Tamura T, Thibert C, Royer C, Kanda T, Abraham E, Kamba M, Komoto N, Thomas JL, Mauchamp B, Chavancy G, Shirk P, Fraser M, Prudhomme JC, Couble P (2000) Germline transformation of the silkworm Bombyx mori L using a piggyBac transposon-derived vector. Nat Biotechnol 18:81–84CrossRefPubMedGoogle Scholar