MARKERS OF THE PHYSIOLOGICALLY INDUCED DNA DOUBLE STRAND BREAKS IN MOUSE SPERMATOCYTES AND YEAST MEIOSIS

The integrity of the human genome is constantly under attack by several exogenous and endogenous sources of DNA damage. Among all types of DNA damage, DNA double-strand break (DSB) is considered to be of the most cytotoxic lesions. During meiosis, DNA DSBs is induced physiologically by the topoisomerase II like protein (Spo11). These induced breaks are repaired by a physiological and complicated repair process known as meiotic recombination (MR). Here, I analyzed and compared the expression of two of these highly conserved proteins, the recombinase Rad51 and the DSB marker phosphorylated enotsih variant γ-H2AX, which involve in the MR process during mouse and yeast meiosis. Consistent with previous studies, the expression analysis of γ-h2ax fluorescent (FL) foci formation during mouse MR show that the induced DSBs during leptotene stage of meiosis are fully repair at the end of pachytene stage except for spontaneous foci that represent persistent un-repaired ones. The recombinase Rad51 clearly marks the MR progression, where foci appear at early zygotene stage and disappear at the end recombination process when scynaptonaemal complex (SC) proteins signal degraded. However, both western blot and foci kinetics analysis of γ-H2A (human and mouse homologue) and Rad51 in WT and Spo11 knockout strains, revealed that γ-H2A is not a good marker for DSBs in during MR of yeast meiosis.