Genetic and cytological mapping of a "Y–2" translocation in the Mediterranean fruit flyCeratitis capitata

Abstract

In this paper we analyze genetically and cytologically a Y – chromosome 2 translocation with several markers, some of which are potentially useful for large scale sex separation. The breakpoint of this Y–2 translocation is located at region 6B on the trichogene polytene chromosome map. It was found that, in strains carrying this TY–2, only 40% of the fertilized eggs survived to the adult stage, 26% of them dying as embryos, 27% as larvae, and 7% as pupae. Early lethality is explained by the nonviability of adjacent-1 products of meiosis containing a deletion of section 1A–6B. The reciprocal segregation products, carrying this chromosome segment in triplicate, survive until late stages. By analyzing the phenotype of these individuals we conclude that all markers used in this study are located outside the triplicated region and that the male determining factor is not included in the piece of the Y chromosome translocated to chromosome 2. The male recombination frequencies of several genes located on chromosome 2 relative to the breakpoint of translocation T5038 have also been studied here.Key words: genetic sexing strain, Medfly polytene chromosome, adjacent-1 product, translocation breakpoint mapping.