cDNA cloning, gene structure, and expression of Broad-Complex (BR-C) genes in the silkworm, Bombyx mori.
To clarify the molecular mechanisms of metamorphosis, we analyzed the Broad-Complex (BR-C) gene in the silkworm, Bombyx mori. We cloned cDNAs for the full coding regions of the Z1, Z2, and Z4 isoforms of BR-C. The Z3 zinc finger sequence was found in the 3'UTR of the Z2 isoform. The predicted amino acid sequence showed high homology with Drosophila and Manduca BR-C proteins. Five bacterial artificial chromosome (BAC) clones were screened from a Bombyx BAC library. Restriction enzyme cleavage maps of 170 kb regions were constructed, and a total of 25.8 kb were sequenced. The BAC analysis showed that the 5'UTR of the BR-C gene consists of the first two exons, while the coding region contains a core region domain with five exons and four zinc finger exons in the order Z1, Z4, Z2, and Z3. Expression analysis revealed 9.5, 6.5, and 5.5 kb BR-C transcripts. These increased during the spinning ecdysone peak on day 6 of the fifth instar when pupal commitment occurs in the Bombyx epidermis. In addition, a small amount of BR-C mRNA was detected in the epidermis before this peak. BR-C mRNA was also expressed in the fat body from day 1 in the fourth instar to day 7 in the fifth instar.
Ijiro
Tomoyuki
T
Division of Molecular Science, Graduate School of Science and Technology, Kobe University, Rokkodai 1-1, Nada, Kobe 657-8501, Japan.
Urakawa
Hisayo
H
Yasukochi
Yuji
Y
Takeda
Makio
M
Fujiwara
Yoshihiro
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development; D022201:Chromosomes, Artificial / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics*; D007814:Larva / Q000235:genetics; D008675:Metamorphosis, Biological / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D016335:Zinc Fingers
D018076:DNA, Complementary; D019476:Insect Proteins; D014157:Transcription Factors