Meiotic double strand DNA breaks and spontaneous mutation in Drosophila melanogaster

Here we use a mutation accumulation study with two experimental groups to test how meiotic DSBs impact the mutational landscape in D. melanogaster. One group carried the allele mei-P22[P22] (also known as mei-P22[1] or mei-P22[McKim]) which is a nonfunctional version of the gene mei-P22. This gene is necessary for the formation of "programmed" or "endogenous" meiotic DSBs. As such, meiotic DSBs occurred in one experimental group and did not in the other. We find that meiotic DSBs have no impact on the rate or spectrum of single nucleotide variants (SNV) or shirt insertions and deletions (INDEL) but that the presence of meiotic DSBs significantly reduces transposable element (TE) activity in the germline. We find that this effect of meiotic DSBs on TE activity occurs across numerous TE families and that no individual family is specifically driving this effect. We also find that this effect seems to occur on a genome-wide scale implicating meiotic DSB (and related) machinery in the silencing of TEs. Our results provide novel insight into the efficacy of meiotic DSB repair, the relationship between meiotic DSBs and TE silencing, and finally the evolution of meiotic recombination and sex more broadly.