Polyploidy and aneuploidy induced by colcemid in Drosophila melanogaster.

Colcemid was fed to Drosophila melanogaster larvae throughout most of the larval period. Surviving individuals were then mated with untreated flies, and their progeny were examined for polyploid flies or flies resulting from X-chromosome nondisjunction. A total of 251 polyploid offspring was recovered from the experimental matings, none from the control. All of the polyploids were evidently triploids, and all but one were obtained from colcemid-fed females: males produced significantly lower frequencies of triploid offspring than females. The highest average frequency of triploid offspring obtained from any treatment group was 18%. Nonrandom distributions of triploid offspring were observed among females raised identically, indicating tht polyploidization occurs mitotically, rather than meiotically, giving rise to clones of tetraploid oogonia. 9 colcemid-fed females produced exclusively triploid offspring. Colcemid also caused a significant increase in X-chromosome nondisjunction in females, though the frequencies of such offspring were at least several-fold lower than the frequencies of triploid offspring. Somatic polyploidy was apparently also indiced since patches of large cells were found on the wings of some flies raised on colcemid-containing food. Various teratological abnormalities were observed among the treated flies, including deformed or missing eyes and partially duplicated thoraxes.