The role of the BR-C locus on the expression of genes located at the ecdysone-regulated 3C puff of Drosophila melanogaster

Abstract

During the third larval instar, the steroid moulting hormone ecdysone activates three temporally distinct puff sets on the D. melanogaster salivary gland polytene chromosome: the so-called intermoult, early and late puffs. Hormonal regulation of intermoult puffs is quite complex and, so far, largely not understood. In order to further investigate this aspect, we have analysed the effects of mutations in a key regulator of the ecdysone response at the onset of metamorphosis, the Broad-Complex (BR-C) locus, on the expression of genes mapping at the 3C intermoult puff. On the basis of an accurate examination of 3C intermoult gene activity in single, carefully staged, third instar larvae of wild-type and BR-C mutant strains, we were able to subdivide these genes into two groups. Each group is characterised by a different temporal expression profile, so that at the beginning of the wandering stage the transcription of the first group declines as group II transcription is induced. Interestingly, the BR-C locus appears to play a regulatory role in establishing this transcriptional switch. By using mutants of each of the three lethal complementation groups, we precisely defined the role of BR-C functions in this developmental transition and we show that this locus also plays an essential role in the early pre-metamorphic hormonal response.

Drosophila Suppressor of Sable Protein [Su(s)] Promotes Degradation of Aberrant and Transposon-Derived RNAs

“…The wild-type temporal patterns of Sgs4 and ng gene expression have been previously characterized (2,13). This analysis has revealed a precise developmental switch in the expression of Sgs4 and three of the ng genes (ng1 to ng3).…”

“…Total RNA was isolated as described previously (13). Northern blots and antisense RNA probes were prepared as described previously (15).…”

The steroid hormone-regulated geneBroad Complex is required for dendritic growth of motoneurons during metamorphosis ofDrosophila

“…BRC proteins regulate the expression of many secondary response genes (Karim et al, 1993;Dubrovsky et al, 1996) in diverse tissues, including salivary glands (Guay and Guild, 1991;von Kalm et al, 1994;D'Avino et al, 1995;Crossgrove et al, 1996;Renault et al, 2001), epidermis (Hodgetts et al, 1995;Chen et al, 2002), fat body (Mugat et al, 2000), imaginal discs (Dunne et al, 2002), and CNS (Liu and Restifo, 1998). BRC mutations fall into three lethal complementation groups, broad (br), 2Bc, and reduced bristles on palpus (rbp), and the most abundant zincfinger isoforms mediate corresponding functions: BRC-Z1 carries rbp ϩ function, whereas br ϩ and 2Bc ϩ functions are mediated by BRC-Z2 and BRC-Z3, respectively (Crossgrove et al, 1996;Sandstrom et al, 1997;Bayer et al, 1997;Liu and Restifo, 1998).…”

Diaphanous regulates myosin and adherens junctions to control cell contractility and protrusive behavior during morphogenesis

“…Immunoblots were quantitated using Image J; we quantitated at least two exposures in each case, with similar results. RNA was prepared and analyzed as described by D'Avino et al (D'Avino et al, 1995). For anti-myosin, embryos were heat-methanol fixed (Müller and Wieschaus, 1996); otherwise embryos were prepared and imaged as described by Fox and Peifer (Fox and Peifer, 2007).…”