Induction of MGE 412 Transpositions in Spermatogenesis of Drosophila Males Separately by Heat and Cold Shock

Abstract

Effects of temperature treatment (heavy heat shock, HHS; heat shock, HS; and cold shock, CS) on the daily productivity of treated males in different spermatogenesis stages have been studied in isogenic line 51 of Drosophila melanogaster. The average productivity was shown to substantially decrease in all cases. The sum of the HS and CS contributions to this decrease was nearly equal to the HHS (the combined HS and CS) contribution, i.e., these contributions were almost additive. The temperature treatments did not kill mature sperm. In the control, mating productivity of day 1 exceeded that of the next day at least by 10–20%. Each day, most sperm in matings was new, i.e., matured during that day. Transposition induction of MGE 412was studied at four spermatogenesis stages after HS and CS. Both temperature treatments were effective but CS had a more pronounced inducing effect. Most temperature-induced transpositions occurred at stage III (meiosis) and IV (spermiogenesis). The day rates of transpositions at different stages were estimated. After HS at the meiosis stage, λ = 0.11 events per initial MGE copy per sperm per day of mating, which is approximately equal to the previous estimates after HHS. After CS at the meiosis stage, λ = 0.51. The transposition hot sites (including the previously known 43B and 97DE as well as a number of new sites) were detected. The lists of transpositions after CS completely included the corresponding lists after HS, which suggests similarity of induction mechanisms underlying CS and HS.