In Drosophila, singed (sn) is a recessive allele of a gene on the X-chromosome t
ID: 198329 • Letter: I
Question
In Drosophila, singed (sn) is a recessive allele of a gene on the X-chromosome that changes bristle shape. A researcher found a singed allele with some unusual characteristics. Females homozygous for this singed allele have singed bristles, but they also have several patches of wild type bristles on their head, thoraces and abdomens. When these females are mated to singed males, some females give only singed offspring, but others give both singed and wild type offspring in variable proportions. How can you explain these results?
Explanation / Answer
Explaination: it clearly seems that the mutation might produced at early cleavage of nuclei. The approximately singed and the wild-type regions show bilateral distribution, support the view that the mutation rised in one of the dividing egg nucleus's X chromosomes of daughter, or, quickly following, in one of the two-cell stage nuclei.