A cytogenetic analysis of x-ray induced "visible" mutations at the yellow locus of Drosophila melanogaster

In the course of a study to determine whether stable terminal deletions of the X chromosome can be recovered, a collection of mutations of yellow, a gene near the tip of the X, was analyzed. Half of the yellow mutations induced by exposure of sperm and spermatids to 4000 R of X-rays were associated with rearrangements detectable in polytene chromosomes. A number of exceptions to the rule that male viable, fertile and non-variegating mutants are unlikely to have grossly rearranged X chromosomes¹⁰ were found. The use of translocation and inversion breakpoints to localize genes may lead to errors unless caution is exercised because rearrangements independent of the specific locus are not uncommon.