科研之友
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摘要
The arylphorin gene of Galleria mellonella is permanently shut off in fat body cells within 48 h following the larval-pupal molt. Experiments were performed to determine the signal for this irreversible inactivation. Interruption of the normal pupal hormonal program, by debraining at day 0 or by head-ligation of pharate pupae, resulted in the presence of arylphorin transcripts for at least 10 days. Nuclear run-off transcription assays showed that persistence of these transcripts in debrained pupae was due to continued transcription rather than increased mRNA stability. Treating debrained pupae with 20-hydroxyecdysone (20-HE) resulted in a rapid decline (within 15 h) of arylphorin transcript levels. Taken together, the available data indicate that normal arylphorin gene inactivation is programmed by the release of 20-HE in the absence of juvenile hormone, which occurs beginning 24 h post-pupation and which initiates adult development. We also revisited the question of the tissue-specificity of Galleria arylphorin gene expression: arylphorin transcripts were detected by northern blot analysis in larval gonadal tissue, albeit at lower levels than in the fat body. Sensitive in situ hybridizations demonstrated that arylphorin transcripts were present in peripheral somatic sheath cells, but not in the enclosed germ line cells. Furthermore, about half of the gonads in batch preparations failed to stain at all, suggesting that unlike fat body cell expression, the gonadal expression of the arylphorin gene may be sex-limited.
- 出版日期1993-1
