Expression pattern of Cubitus interruptus from the mulberry silkworm Bombyx mori in late developmental stages
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A partial genomic clone of Bombyx mori homologue of the segment polarity gene Cubitus interruptus (BmCi), encoding the conserved zinc finger domain and harbouring two introns, has been characterized. BmCi was expressed in the silkglands of B. mori from embryonic to the late larval stages(3rd, 4th and 5th intermoults). The expression was confined to the anterior region of the middle silkglands, overlapping with the domain of sericin-2 expression and excluding the domains of Bm invected expression, namely the middle and posterior regions of the middle silkglands. In the wing discs, the expression was restricted to the anterior compartment, which increased from 4th to 5th larval intermoults and declined later in the pupal wing buds. In gonadal tissues (both ovaries and testes) BmCi was expressed from the larval to pupal stages. The transcripts were localized to the sperm tubes containing spermatogonia in the testis of Bombyx larvae. BmCi expression, however, was not detected in any of these tissues during the moulting stages. Expression of Ci in the wing discs and gonads is evolutionarily conserved, while the silkgland represents a novel domain. Our results imply that BmCi is involved in the specification and maintenance of micro-compartment identity within the middle silkglands.
KeywordsBmCi expression Fate specification Gonadal development Segment polarity genes Silkgland development Wing discs
We thank Dr. Pierre Couble, CGMC, Univ. Lyon, France for the Fkh antibodies, the sericin-2 clone and for helpful discussions, and Dr. S. Sreekumar, from the Central Silk Research and Training Institute (CSB), Mysore, for the supply of silkworm embryos and larvae. We also thank our Institute Divisional DNA Sequencing and microscopic facilities. S.D. is the recipient of a Senior Research Fellowship from CSIR, New Delhi. We thank the Department of Biotechnology, Govt. of India for financial support.
- Amanai K, Suzuki Y, Ohtaki T (1994) Involvement of a maternally transcribed lectin gene in the early developemnt of Bombyx mori. Roux Arch Dev Biol 203:397–401Google Scholar
- Bello B, Horard B, Couble P (1994) The selective expression of silk-protein-encoding genes in Bombyx mori silk gland. Bull Inst Pasteur 92:81–100Google Scholar
- Couble P, Prudhomme J-C (2002) Perspectives in silkworm (Bombyx mori) transgenesis. Curr Sci 83:432–438Google Scholar
- Hui CC, Slusarki D, Platt KA, Holmgren R, Joyner AL (1994) Expression of three mouse homologs of the Drosophila segment polarity gene Cubitus interruptus, Gli, Gli-2 and Gli-3, in ectoderm- and mesoderm-derived tissues suggests multiple roles during postimplantation development. Dev Biol 162:402–413CrossRefPubMedGoogle Scholar
- Sambrook J, Frisch EF, Maniatis T (1989) Analysis of genomic DNA by Southern hybridization. In: Nolan C (ed) Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, pp 9.31–9.58Google Scholar
- Singh A, Gopinathan KP (1997). Analysis of gene expression during embryonic development in mulberry silkworm Bombyx mori. Curr Sci 72:214–218Google Scholar
- Takami T, Kitazawa T (1960) Normal stages of embryonic development in the silkworm, Bombyx mori. Tech Bull Sericult Exp Sta 75:1-31Google Scholar
- Tiniakov GG, Terentieva EL (1933) Cubitus interruptus, a new genovariation of the fourth chromosome of Drosophila melanogaster. Genetics 18:117–120Google Scholar
- Toyama K (1909) Studies on the silkworm, Bombyx mori [in Japanese]. Meibundo, TokyoGoogle Scholar