Constructing balancer chromosomes for genetic screens in Drosophila hydei.

We used a screen for maternally generated late embryonic lethals as a new method for the isolation of inversions that are suitable for the balancing of mutations in Drosophila hydei. The recovery of several inversions by this method demonstrates that female meiosis in D. hydei apparently differs from meiosis in female D. melanogaster, since in D. hydei the defective chromosomes which are generated by a single crossing-over within a paracentric inversion can be recovered via the egg nucleus. In addition, the classic method of crossingover suppression was used in order to isolate more inversions and to improve the balancing capacities of inversions. We succeeded in constructing chromosomes that allow the balancing of mutations on nearly the whole genome of D. hydei. We discuss here whether or not this method is suited for application to other organisms.