Isolation and characterization of novel mutations of the Broad-Complex, a key regulatory gene of ecdysone induction in Drosophila melanogaster

• Published in: Insect biochemistry and molecular biology 2002-02, Vol.32 (2), p.121-132
• Main Authors: Gonzy, G, Pokholkova, G.V, Peronnet, F, Mugat, B, Demakova, O.V, Kotlikova, I.V, Lepesant, J.-A, Zhimulev, I.F
• Format: Article
• Language: English
• Subjects: Animals; Broad-Complex; Broad-Complex (BR-C) gene; Chromosomes; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila Proteins; Ecdysone - biosynthesis; Larva; Mutagenesis; P-transposon mutagenesis; Polytene chromosomes; Protein Isoforms - genetics; Protein Isoforms - metabolism; Puffs; Transcription Factors - genetics; Transcription Factors - metabolism; Zinc finger; Zinc Fingers
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/S0965-1748(01)00097-2

Seven new alleles of the Broad-Complex gene of Drosophila melanogaster, which encodes a family of four zinc finger protein isoforms BR-C Z1, Z2, Z3 and Z4, were generated by transposase-induced mobilization of a P[Zw] element inserted in either the first intron downstream from the P165 promoter or the exon encoding the Z2-specific zinc finger domain. They were characterized by genetic complementation tests, molecular mapping and cytogenetic analysis of their effect on ecdysone-induced puffing and BR-C proteins binding to polytene chromosomes. Four mutations that correspond to three overlapping deletions and one tandem insertion of the P[Zw] element are located in the intron. They provide evidence that regulatory elements essential for a correct expression of the BR-C Z2 and BR-C Z3 transcripts are located within the intron downstream from the P165 promoter. Three mutations correspond to internal deletions of the locus and exhibit a complete loss of all BR-C + genetic functions in the complementation and cytogenetic tests. They thus provide well characterized new amorphic reference alleles of the BR-C gene. The precise cytogenetic location of more than 300 binding sites of BR-C proteins on larval salivary gland polytene chromosomes was determined by immunostaining using specific antibodies. Sites were found in big ecdysone inducible puffs, constitutively active small puffs as well as interbands. A complete list of the major sites on all four salivary gland polytene chromosomes of BR-C + larvae is presented.