Modification by chloramphenicol of diethyl sulphate-induced male recombination frequency in Drosophila melanogaster.

To study the effect of chloramphenicol (CPL, an inhibitor of protein synthesis) on diethyl sulphate (DES, a potent mutagen) induced male recombination frequency, the F1 (+/aristaless dumpy black cinnabar, al dp b cn) larvae of D. melanogaster were given a pre- or post-treatment of CPL with DES during the first or second half of larval life. In order to determine sensitivity of different germ cell stages to the induction and modification of male recombination frequency, five 3-day broods were taken from every F1 male. DES showed toxic effect on egg-to-adult development. DES was found to be a potent recombinogen. Several cases of non-reciprocal male recombination were recorded. The most frequent recombinant phenotype observed was b cn followed by cn and al. Majority of the recombinants appeared in clusters suggesting their pre-meiotic origin. DES produced male recombination at a stage where only primary spermatocytes were present in the larval testes. CPL when given as a pre- or post-treatment with DES revealed highest frequency of male recombination in broods that represented effect of treatment on spermatogonia predominantly. CPL enhanced the overall level of male recombination produced by DES in both pre- and post-treatments. The results suggested the role of protein synthesis in induction of male recombination in D. melanogaster. In addition, the present experiments give a methodology of enhancing the frequency of chemically-induced male recombination.

Gradual decline of formaldehyde-induced male recombination in successive generations of Drosophila melanogaster.

Transmission of formaldehyde (FA)-induced male recombination was studied in D. melanogaster for three generations. Among recombinants, al dp was the most and b pr the next most frequent phenotype in the progenies of F1, TC1, TC2 and TC3 males of genotype + /al dp br. Non-reciprocal male recombination for dp-b and b-pr regions whereas reciprocal male recombination for al-dp region were noted. Percentages of recombinants observed in TC1 (1.052), TC2 (0.876), TC3 (0.698) and TC4 (0.497) progenies of D. melanogaster males were not statistically different from each other in any two successive generations. A continuous but gradual decline in the frequency of FA-induced male recombination was observed in the three subsequent generations studied.