“We know that birth defects and miscarriages can arise from defects that occur in meiosis prophase that are related to pairing and recombination,” said Burgess. The study provides the first live view into interchromosomal dynamics during meiosis. Their movements were dynamic, with only a few tethers required to keep a pair bound together. Instead, the team uncovered that the chromosomes weren’t stable during homolog pairing.

“We expected that the chromosomes would start out unpaired and then over time, they would get closer and closer together and progressively more and more paired.” “What we found was really surprising,” said Burgess. Using yeast ( Saccharomyces cerevisiae) as a model organism, the team successfully observed homolog pairing in real-time. In a study appearing in the Proceedings of the National Academy of Sciences, Burgess and her colleagues provide an unprecedented glimpse into the homolog pairing phase of meiosis (prophase I). “Most studies looking at chromosomes in meiosis focus on cells that have been fixed, so it’s just a snapshot that shows whether the homologs are paired or not.” “Homolog pairing has been seen for 130 years, but the mechanism behind it is not really well understood,” said Professor Sean Burgess, Department of Molecular and Cellular Biology. Despite being studied for more than 100 years, mysteries about the process still abound. Errors in this process can lead to an incorrect number of chromosomes in sex cells, which can result in birth defects and miscarriages. In the choreography of meiosis-the process responsible for sex cell division in all eukaryotic life-the pairing of homologous chromosomes (homologs) is essential.

Prophase model