ANALYSIS OF THE SEX-CHROMOSOMES OF THE MEDITERRANEAN FRUIT FRY BY MICRODISSECTED DNA PROBES

In the Mediterranean fruit fly: Ceratitis capitata, the sex-determinin g region maps to the long an of the Y chromosome. DNA from this region of the Y chromosome and, for comparison, from the tip of the long arm of the X chromosome, was isolated by microdissection and amplified by degenerate oligonucleotide primer PCR (DOP-PCR). FISH of the Y-chromo somal microdissection products medY1-medY5 to mitotic chromosomes reve aled hybridization signals on most of the long arm of the Y chromosome , including the male-determining region, and on the long arm of the X chromosome, as well as weaker signals on the autosomes, some of which were located in the heterochromatin next to the centromeres. The X-chr omosomal microdissected probe medX1 revealed strong signals on the sex chromosomes and randomly distributed signals on the autosomes. Chromo somal in situ suppression hybridization indicates that the Y chromosom e contains considerable amounts of Y-enriched and Y-specific sequences and that X-enriched sequences are present on the long arm of the X ch romosome. The microdissected probes medY1, medY2, and medX1 hybridize to the sex chromosomes of two closely related species, Ceratitis rosa and Trirhithrum coffeae.