Reproductive characteristics of mouse males are influenced by the mouse female pheromone 2,5-dimethylpyrazine in the C57BL/6 strain

The influence of the mouse female pheromone 2,5-dimethylpyrazine was studied on significant reproductive characteristics in C57BL/6 males. With this purpose the frequency of pheromonally induced sperm head abnormalities and dominant lethal frequency was analyzed. It is shown, that the level of different sperm head abnormalities increases significantly after exposure with the pheromones. Simultaneously with it the frequency of dominant lethals elevates significantly in the progeny of the treated males. Connection of the revealed effects with the destabilizing influence of the pheromone on the genome of dividing germ and somatic cells at laboratory mice is discussed

Differential Response of Mouse Male Germ-Cell Stages to Radiation-Induced Specific-Locus and Dominant Mutations

In an attempt to provide a systematic assessment of the frequency and nature of mutations induced in successive stages of spermato- and spermiogenesis, X-irradiated male mice were re-mated at weekly intervals, and large samples of progeny, observed from birth onward, were scored and genetically tested for recessive mutations at seven specific loci and for externally recognizable dominant mutations. Productivity findings provided a rough measure of induced dominant-lethal frequencies. A qualitative assessment of specific-locus mutations (which include deletions and other rearrangements) was made on the basis of homozygosity test results, as well as from information derived from more recent complementation studies and molecular analyses. Both recessive and dominant visibles revealed clear distinctions between spermatogonia and postspermatogonial stages. In addition, differences for both of these endpoints, as well as for presumed dominant lethals, were found among various postspermatogonial stages. It may be concluded that radiation produces its maximum rates of genetic damage in germ-cell stages ranging from midpachytene spermatocytes through early spermatids, a pattern unlike any of those that have been defined for chemicals; further, the frequency peaks for radiation are lower and broader. The difference between post-stem-cell stages overall and stem-cell spermatogonia was smaller than is generally found with chemicals, not only with respect to the frequency but also the nature of mutations.

Evidence for an inducible repair-recombination system in the female germ line of Drosophila melanogaster. II. Differential sensitivity to gamma rays.

In a previous paper, we reported that the reactivity level, which regulates the frequency of transposition of I factor, a LINE element-like retrotransposon, is enhanced by the same agents that induce the SOS response in Escherichia coli. In this report, we describe experimental evidence that, for identical genotypes, the reactivity levels correlate with the sensitivity of oogenesis to gamma rays, measured by the number of eggs laid and by frequency of dominant lethals. This strongly supports the hypothesis that the reactivity level is one manifestation of an inducible DNA repair system taking place in the female germ line of Drosophila melanogaster. The implications of this finding for the understanding of the regulation of I factor are discussed and some other possible biological roles of this system are outlined.