Replication and expression of an X-linked cluster of Drosophila chorion genes

Suki Parks, Barbara Wakimoto, Allan Spradling

Research output: Contribution to journalArticle

Abstract

Two 80- to 100-kb chromosomal replicons containing clustered chorion genes amplify in the ovarian follicle cells during the final 22 hr of Drosophila oogenesis. We have studied the relationship between amplification and transcription within one of these domains, located at 7E10-7F3,4 on the X chromosome. A tandem cluster of six genes, encoding chorion structural proteins s36-1, s38-1, and four putative minor chorion protein mRNAs, was mapped in the central 18 kb of the amplified domain, a region showing the highest levels of amplification. The regions both proximal and distal to this gene cluster, where lower levels of amplification occur, were also transcribed in ovary, but mRNAs produced specifically during choriogenesis were not detected. Thus, differences in amplification do not appear to modulate differential RNA accumulation. Instead, the gradient of amplification observed in egg chamber DNA may simply reflect the mechanism of amplification. In the female sterile mutation, In(1)ocelliless, a chromosomal rearrangement separates the central gene cluster into two parts, only one of which retains the capacity to amplify. Genes located within the unamplified portion of the ocelliless chromosome were expressed at the appropriate time during oogenesis, but at a 5- to 10-fold reduced level of RNA per gene. Thus neither cluster integrity nor amplification are required for the normal developmental program of gene expression within the cluster.

Original languageEnglish (US)
Pages (from-to)294-305
Number of pages12
JournalDevelopmental Biology
Volume117
Issue number1
DOIs
StatePublished - 1986
Externally publishedYes

ASJC Scopus subject areas

  • Developmental Biology

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