After more than a century of study, mysteries still remain about the process of meiosis—a special type of cell division that helps ensure genetic diversity in sexually-reproducing organisms. Now, researchers at Stowers Institute for Medical Research, in Kansas City, Missouri, shed light on an early and critical step in meiosis. The research, published online on October 27, 2011 in Current Biology, clarifies the role of key chromosomal regions called centromeres in the formation of a structure known as the synaptonemal complex (SC). "Understanding this and other mechanisms involved in meiosis is important because of the crucial role meiosis plays in normal reproduction—and the dire consequences of meiosis gone awry," says Dr. R. Scott Hawley, who led the research at Stowers. "Failure of the meiotic division is probably the most common cause of spontaneous abortion and causes a number of birth defects such Down syndrome," Dr. Hawley says. Meiosis reduces the number of chromosomes carried by an individual's regular cells by half, allocating precisely one copy of each chromosome to each egg or sperm cell and thus ensuring that the proper number of chromosomes is passed from parent to offspring. And because chromosomes come in pairs—23 sets in humans—the chromosomes must be properly matched up before they can be divided up. "Chromosome 1 from your dad has to be paired with chromosome 1 from your mom, chromosome 2 from your dad with chromosome 2 from your mom, and so on," Dr. Hawley explains, "and that's a real trick. There's no room for error; the first step of pairing is the most critical part of the meiotic process. You get that part wrong, and everything else is going to fail." The task is something like trying to find your mate in a big box store.
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