The genome of the Mediterranean fruitfly Ceratitis capitata: localization of molecular markers by in situ hybridization to salivary gland polytene chromosomes.

We hybridized cloned DNA segments to salivary gland polytene chromosomes of the medfly, Ceratitis capitata, and thus established molecular markers for 24 sites on 6 out of 10 autosomal arms. An additional marker identified a medfly repetitive element that hybridizes to approximately 100 autosomal sites as well as a granular network that is thought to represent the X chromosome. Some of the markers correspond to 9 characterized transcription units, while 17 remain anonymous; at least 3 of the latter are restriction fragment length polymorphism (RFLP) markers. The characterized transcription units document that chromosomal arm 5L of C. capitata is homologous to the Drosophila melanogaster X chromosome, in agreement with previous inferences based on the extensive conservation of linkage groups in Diptera.