Chromosome segregation in mammalian meiosis

We are trying to identify mechanisms that ensure each egg receives a single copy of every chromosome. The inheritance of too many or too few chromosomes can result in spontaneous miscarriages or severe birth defects as in Down’s Syndrome or trisomy of chromosome 21. We know that cells in the body regulate the equal distribution of chromosomes by entrapping sister chromosomes within protein rings. These rings are only destroyed when cells are ready to divide. In women, the rings must hold together sister chromosomes in eggs from birth until fertilization, which can be separated by decades. We are investigating how these rings are stably maintained. Loss of rings over time could be responsible for maternal age-related infertility. We are using animal models to study chromosome segregation in eggs with the aim to understand the equivalent processes in humans. We are studying eggs lacking specific proteins that are known to be important for chromosome segregation in other organisms. We are taking movies of mutant eggs carrying fluorescently labelled chromosomes to identify which aspects of chromosome segregation are defective due to loss of a particular protein. We also hope to identify new regulators of the egg divisions by studying infertile mutants.