A novel transvection phenomenon affecting the white gene of Drosophila melanogaster.

Abstract

The zeste mutation of Drosophila melanogaster suppresses the expression of white genes in the eye. This suppression is normally dependent on there being two copies of w+ located close to each other in the genome--they may either be in cis (as in a tandem duplication of w+) or in trans, i.e. on homologous chromosomes. Duplicated w+ genes carried by a giant transposing element, TE146(Z), are suppressed by z whether they are in direct (tandem) or inverted order. The tandem form of the TE is very sensitive to a rearrangement on the homologous chromosome--many rearrangements with breakpoints "opposite" the TE's insertion site prevent the interaction between the white genes on a z background. These aberrations act as dominant suppressors of zeste that are specific to the tandemly duplicated form of TE146(Z). The inverted form of the TE146(Z) presumably pairs as a hairpin loop; this is more stable than the tandem form by the criterion that its zeste phenotype is unaffected by any of the aberrations. This effect of rearrangements has been used as the basis for a screen, gamma-ray induced aberrations with at least one breakpoint opposite the TE site were recovered by their suppression of the zeste phenotype.

An Exploration of the Sequence of a 2.9-Mb Region of the Genome of Drosophila melanogaster: The Adh Region

“…This is much less than the 9% of the genome as a whole estimated of these were mapped to restriction fragments in the 450-kb "Adh" walk from Ashburner's laboratory (Chia to be composed of such sequences (Spradling and Rubin 1981). The reason for this difference is probably et al 1985;McGill et al 1988;Davis et al 1990Davis et al , 1997Gubb et al 1990;Cheah et al 1994;McNabb et al 1996), that the density of transposable elements is higher in the heterochromatic and peri-heterochromatic regions while others had been mapped to the vasa (Lasko and Ashburner 1988), Su(H) (Schweisguth and Posa-of the chromosomes (see Sun et al 1997). Perhaps only half the retroviral elements are euchromatic.…”

“…rial serine proteases, but is most similar (36% identity over 61% of its length) to the antibacterial serine prote-Tim17: This gene encodes a preprotein translocase of the inner mitochondrial membrane that is highly ase, Limulus factor D, from the Japanese horseshoe crab (Kawabata et al 1996; SPTREMBL: P91817). The conserved in different organisms.…”

Topological Constraints on Transvection Between white Genes Within the Transposing Element TE35B in Drosophila melanogaster

“…Localized topological constraints that affect the zeste phenotype of TE35B(Z) can also be caused by breakpoints close to 35B on the homologous second chromosome (GUBB et al 1990). The purpose of this paper is to characterize both spontaneous and gamma rayinduced changes on the TE35B(Z) chromosome that suppress transvection between intact w + genes.…”

Homologous association of the Bithorax-Complex during embryogenesis: consequences for transvection in Drosophila melanogaster

“…Whereas a translocation of one allele of the BX-C to the X chromosome, namely Tp(3;1)P115, leads to a complete loss of transvection at the Ultrabithorax (Ubx) locus (Micol and García-Bellido, 1988), transvection phenotypes at the abdominal-A (abd-A) and Abdominal-B (Abd-B) loci are strongly reduced but not eliminated (Jijakli and Ghysen, 1992). Also, there is no strict rule for the proximity of breakpoints to disrupt transvection at different genes suggesting that this property is intrinsic to the gene (see Gelbart, 1982;Smolik-Utlaut and Gelbart, 1987;Gubb et al, 1990Gubb et al, , 1997. There is a clear need for assays of homologous chromosome pairing that do not rely solely on phenotypes of adult flies.…”