Meiotic recombination and chromosome-specific differences in spontaneous nondisjunction

Crossovers during meiosis ensure correct segregation of homologous chromosomes during meiosis, safeguarding against aneuploidy in gametes. Crossovers are formed via homologous recombination, a process that repairs a double-strand DNA break using a homologous template. The position and number of crossovers is tightly regulated in a phenomenon known as "crossover patterning," but the mechanisms of this patterning remain poorly understood. Similarly, much remains unknown about homologous recombination, and some experimental data is incongruent with the classical model of recombination. Here, we explore meiotic crossovers in several contexts. We first interrogate recombination landscape in spontaneous meiotic nondisjunction of chromosome 2. In contrast to prior data showing perturbed recombination in X chromosome nondisjunction, we find that recombination landscape is not strongly altered in chromosome 2 nondisjunction. We additionally provide evidence that these discrepancies may be attributed to differences in chromosome shape. We furthermore describe efforts in whole-genome sequencing to refine our current understanding of meiotic recombination, and provide a computational simulation of meiotic recombination designed to assist in similar genomic experiments.