Shirleen Roeder is using budding yeast to study chromosome pairing, synapsis, and recombination during meiosis and the coordination of these processes with meiotic cell-cycle progression. Checkpoints ensure the correct order of events within the cell cycle. For example, the DNA replication checkpoint prevents mitotic chromosome segregation until chromosomes are fully duplicated.
Checkpoints also operate in meiotic cells.
Proper chromosome segregation at the first division of meiosis depends on a complex series of interactions between homologous chromosomes. These include the formation of the synaptonemal complex, which holds homologues closely apposed along their lengths during the pachytene stage of meiotic prophase. I reductional division. As a consequence, mutants defective in recombination and chromosome synapsis arrest at midmeiotic prophase. Examples include zip1, which lacks a structural component of the synaptonemal complex, and hop2, which undergoes extensive synapsis between nonhomologous chromosomes.