The ovo gene of Drosophila encodes a zinc finger protein required for female germ line development.

Abstract

As defined by dominant and recessive ovo mutations, the ovo gene is required for development of the Drosophila female germ line, and does not exert any function in males or in somatic tissues. However, reversion of dominant ovo mutations can result in new phenotypes that are not related to the female germ line: the svb and lzl mutations affect cuticle and eye development, respectively. We have identified a 7.2 kb genomic fragment that rescues ovo mutations in transgenic Drosophila and thus contains all sequences necessary for ovo+ function. This fragment has been sequenced almost in its entirety, defining the ovo locus at the molecular level. Multiple copies of the same fragment also rescue the lzl mutation. They do not rescue svb mutations, in agreement with genetic evidence that the svb function requires additional, more distal sequences. Nevertheless, a number of transposable element insertions that induce a svb phenotype interrupt the coding sequence of ovo. Taken together, the genetic and molecular data indicate the existence of a complex locus, where the ovo and svb functions depend on overlapping coding sequences but distinct regulatory elements. The data also suggest a model for the lzl phenotype. Expression of ovo at the RNA level is detectable at stage 8 of oogenesis in nurse cells and persists through the rest of oogenesis and in early embryogenesis. The ovo transcript encodes a protein of at least 1209 amino acids with four zinc fingers, suggesting that ovo might be a transcription factor required for female germ line maintenance and gametogenesis.

Gsh‐1: A novel murine homeobox gene expressed in the central nervous system

“…In addition, there is an eight amino acid polyalanine tract encoded by bases 522 to 545. Similar polyalanine runs have been previously observed in several developmentally important genes, including engrailed (Macdonald et al, 19861, euenskipped (Poole et al, 1985), runt (Kania et al, 1990), cut (Blochinger et al, 1988), and ouo (Mevel-Ninio et al, 1991) in Drosophila. This motif may form an alpha helix structure in transcription repression domains (Han and Manley, 1993a,b).…”

Multiple products from the shavenbaby-ovo gene region of Drosophila melanogaster: relationship to genetic complexity.

“…Three dominant female-sterile alleles either arrest oogenesis at previtellogenic stages or allow the production of defective eggs (6). Since these mutations are partially suppressed by extra copies of the wild-type ovo gene (6,13,23), they have the property of being antimorphic, or dominant negative, with respect to wild-type gene function. The early action of ovo in female germ line development is also indicated by the ability of the dominant ovo alleles to suppress partially P-M hybrid dysgenesisinduced female germ line cell death (39).…”

“…A 5.0-kb ovarian poly(A)+ mRNA ovo candidate transcript that is female specific and germ line dependent in adult flies has been identified (13,23). Mevel-Ninio et al (23) isolated and sequenced cDNAs from an 8-to 12-h embryonic cDNA library and a 6.7-kb genomic DNA segment.…”

“…Mevel-Ninio et al (23) isolated and sequenced cDNAs from an 8-to 12-h embryonic cDNA library and a 6.7-kb genomic DNA segment. This latter DNA segment was sufficient to rescue ovo mutations, but not svb mutations, when reintroduced into D. melanogaster by Pelement-mediated germ line transformation (23). A substantially overlapping 10-kb fragment had the same genetic properties (13).…”

“…A substantially overlapping 10-kb fragment had the same genetic properties (13). The open reading frame (ORF) of the embryonic cDNA clone apparently codes for a protein containing four Cys2-His2 zinc finger DNA-binding motifs (23).…”