Somatic Crossing Over and Its Genetic Control in Drosophila

I N Drosophila, somatic crossing over in the hypodermal cells provides a means of exploring developmental patterns and of studying the effects of certain genes in specialized groups of cells. Mitotic recombination makes certain genes homozygous in parts of the diploid organism. The fact that crossing over can take place in somatic cells as well as in the germ line has led to the suggestion that the genetic analysis of slow-breeding animals such as man might be accomplished in tissue culture. Somatic mosaicism resulting from somatic recombination is a relatively rare phenomenon, however, even in Drosophila, and has not been detected in other higher animals. It might be supposed a selective advantage would be conferred by factors preventing this type of exchange, with its potential for uncovering lethal or deleterious genes.