The Drosophila Eip78C gene is not vital but has a role in regulating chromosome puffs.
We have generated a number of chromosomal aberrations that disrupt the early-late ecdysone-induced 78C puff gene (Eip78C, ecdysone-induced protein, FlyBase name for the E78 gene of Stone and Thummel 1993), which encodes the two members of the nuclear hormone receptor superfamily Eip78C-A and Eip78C-B. The aberrations include deletions of the ligand-binding/dimerization domain of both, inversions that split Eip78C-A but retain residual Eip78C-B expression, and a small deletion specific for Eip78C-B. We find that wild-type Eip78C functions are completely dispensable for normal development under laboratory conditions. However, we show that Eip78C-B is required for the maximal puffing activity of a subset of late puffs (63E and 82F) since these puffs are reduced in size in Eip78C-B mutant backgrounds. Paradoxically the same late puffs are reduced, as well as at least one other, when the Eip78C-B cDNA is overexpressed from a heat shock promoter. These data indicate either that Eip78C function is redundant or that it plays a subtle modulating role in the regulation of chromosome puffing.
Russell
S R
SR
Department of Genetics, University of Cambridge, United Kingdom. sr120@mole.bio.cam.ac.uk
Heimbeck
G
G
Goddard
C M
CM
Carpenter
A T
AT
Ashburner
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D002875:Chromosomes; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D017344:Genes, Insect; D007301:Insect Hormones / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*
D007301:Insect Hormones; D018160:Receptors, Cytoplasmic and Nuclear