A Simplified Strategy for Introducing Genetic Variants into Drosophila Compound Autosome Stocks

Drosophila stocks bearing compound chromosomes, single molecules of DNA that carry the genomic complement of two chromosomes, are useful tools for studying meiosis and mitosis. However, these stocks cannot easily be crossed to stocks with regular chromosomes, due to the lethality of the resulting whole-chromosome aneuploidy. This prevents the examination of interesting genetic variants in a compound chromosome background. Methods to circumvent this difficulty have included the use of triploid females or nondisjunction (caused by either cold-induced microtubule depolymerization or meiotic mutants.) Here we present a new approach for crossing compound chromosomes that takes advantage of the nonhomologous segregations that result when multiple chromosomes in the same genome are prevented from meiotic crossing over by heterozygosity for balancer chromosomes. This approach gives higher yields of the desired progeny in fewer generations of crossing. Using this technique, we have created and validated stocks carrying both a compound-X and compound-2, as well as compound-2 stocks carrying the meiotic mutant nod.