Drosophila forked locus.

A 40-kilobase-pair region of the Drosophila X chromosome from band 15F was cloned, and DNA insertions were indentified for the forked alleles f1, f3, f3n, f5, f36a, fs, and fx. The positions of these insertions are consistent with the organization of the two pseudoallelic series present at the forked locus. Three RNAs of 0.8, 2.6, and 3.3 kilobases are transcribed from this chromosomal region. The 0.8-kilobase transcript(s), present at the larval and adult stages, and the 3.3-kilobase transcript, present at each developmental stage, are unaffected by the forked mutations examined. Only the 2.6-kilobase RNA, present exclusively at the pupal stage, was observed to be less abundant in each of the forked mutants analyzed, consistent with this transcript being the product of the forked gene.