Modeling pairing dynamics of homologous chromosomes during Prophase I in Saccharomyces cerivisae using polymer physics

The development of viable offspring during sexual reproduction requires properly formed egg and sperm cells—the products of meiosis. During meiosis, homologous chromosomes pair and exchange genetic material, and errors in this process can result in defective daughter cells associated with miscarriages and birth defects. Pairing occurs in Prophase I, during which linkages tether and align the homologs together. We explore the dynamics associated with this pairing process in Saccharomyces cerevisiae through a polymer physics model of two randomly linked flexible polymers. This model recapitulates the heterogeneous subdiffusive behavior of chromosomal loci observed experimentally, as well as the temporal behavioral shifts that signify the progressively increasing number of linkages throughout Prophase I. We develop a predictive model for these linkages by calculating the evolving probability distribution for their genomic positions. Furthermore, the effect of cohesin-induced looped chromosomal structures on linkage formation is implemented in our model to study the competition between the fundamental polymer physics of chromosomes and the various biological influences that dictate linkage formation.