Project Summary/Abstract Sexually reproducing organisms rely on meiosis, a specialized cell division that produces haploid gametes such as sperm and eggs, to restore the genetic content of the zygote through fertilization. Errors in this process lead to the production of offspring with an abnormal number of chromosomes or aneuploidy, and this is a major cause of human miscarriages and birth defects such as Down syndrome. Accurate segregation of chromosomes during meiosis requires that they pair, synapse, and undergo crossover recombination with their homologs. Although genetic studies over the decades have identified a list of proteins that are essential for meiotic processes, it remains largely unknown how these protein machines work together to orchestrate chromosome dynamics. My research program will investigate these fundamental processes by combining biochemical and structural analysis using purified components, with the ability to examine meiosis in the context of highly tractable C. elegans germline. Early in meiosis, chromosomes are dramatically reorganized into arrays of chromatin loops tethered to a proteinaceous axis, and this is essential for all major meiotic events