Expression pattern of Cubitus interruptus from the mulberry silkworm Bombyx mori in late developmental stages

Abstract

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.

Proteome analysis of silk gland proteins from the silkworm,Bombyx mori

“…In the silk gland, we detected a transcription factor of TALE/PBX protein (spot 26), which is known to be essential for the activity of HOX proteins [42]. Therefore, it is possible that the PBX protein is involved in interactions with HOX proteins such as antennapedia, ultrabithorax, and even-skipped, which were reported to be synthesized in the silk gland [43].…”

Regulation of Silk Genes by Hox and Homeodomain Proteins in the Terminal Differentiated Silk Gland of the Silkworm Bombyx mori

“…Similar to the silk protein genes, Hox and several homeobox genes are known to be expressed with sublocal specificities along the AP axis of the silk gland ( Table 1 ) [ 6 , 46 , 47 , 55 , 74 , 75 , 76 ]. The anterior Hox genes labial ( lab ) and Scr are mainly expressed in the ASG, whereas the expression of central Hox genes such as Antp , Ultrabithorax ( Ubx ) and abdominal-A ( abd-A ) is absent in the ASG [ 47 ].…”

“…Although we have not yet detected the structural border within the PSG, it may be divided into subparts with different functions. The segment polarity gene engrailed ( en ) and its paralogue invected ( in ) are strongly expressed in the ASG and posterior portions of the MSG [ 47 , 74 , 76 ]. The Pit/Oct/Unc-86 (POU)-homeodomain protein gene POU-M1 is also strongly expressed in the ASG and MSG-A [ 46 , 54 ].…”

“…Since Antp , en and in are specifically expressed in the MSG [ 47 , 74 , 76 ], we prepared recombinant proteins of Antp and En, and determined whether these proteins bind to the −70 element. Although both proteins bound to the −70 element of the ser1 promoter, Antp but not En showed a similar DNA-binding specificity to that of MIC [ 47 ].…”

Hedgehog promotes cell proliferation in the midgut of silkworm, Bombyx mori

“…BmCi has been characterized in Bombyx mori (Dhawan & Gopinathan, ). BmCi is involved in the maintenance of micro‐compartment identity within the middle silk glands (Dhawan & Gopinathan, ). In the prothoracic gland of B. mori , five genes that encode proteins with high sequence similarity to Patch and one gene encoding Smo have been identified (Alexandratos et al ., ).…”