Developmental effects of a chimeric ultraspiracle gene derived from Drosophila and Chironomus.
The ultraspiracle (usp) gene encodes a nuclear receptor that forms a heterodimer with the ecdysone receptor (EcR) to mediate transcriptional responses to the insect steroid hormone, 20-hydroxyecdysone (20HE). The responses ultimately elicit changes associated with molting and metamorphosis. Although Ultraspiracle (USP) is required at several developmental times, it is unclear whether USP plays stage-specific roles in Drosophila. A chimeric transgene (d/cusp), produced by replacing the ligand-binding domain (LBD) of Drosophila USP with the equivalent domain from another Diptera, Chironomus tentans, was tested for its ability to rescue Drosophila usp mutants from early larval lethality. A single copy of the d/cusp was sufficient to rescue transformants from several lines through larval development but they died suddenly during the late third instar. Additional doses of d/cusp were required to allow survival through the adult stage, but they did not restore a normal prepupal contraction. Thus, the arrest at the onset of metamorphosis apparently is caused by the impaired ability of the chimeric USP to mediate a stage-specific function associated with the LBD.
Henrich
V C
VC
Department of Biology, University of North Carolina-Greensboro, Greensboro, North Carolina 27402-6174, USA. vincent_henrich@uncg.edu
Vogtli
M E
ME
Antoniewski
C
C
Spindler-Barth
M
M
Przibilla
S
S
Noureddine
M
M
Lezzi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002678:Chimera / Q000235:genetics; D002683:Chironomidae / Q000235:genetics*; D004274:DNA, Recombinant; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D019281:Dimerization; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007814:Larva / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D011987:Receptors, Steroid / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D014170:Transformation, Genetic
D004274:DNA, Recombinant; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D011987:Receptors, Steroid; D014157:Transcription Factors; C066030:USP protein, Drosophila; C055469:ecdysone receptor; D004441:Ecdysterone; C008999:ponasterone A