How sex evolves… explained through genetics and cell division.
Source: Lawrence Berkeley National Laboratory
Date: December 4, 2006
Sex is a boon to evolution; it allows genetic material from parents to recombine, giving rise to a unique new genome. But how did sex itself evolve” Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have found clues to one part of this complex question in ongoing studies of the nematode Caenorhabditis elegans.
Abby Dernburg, of Berkeley Lab’s Life Sciences Division and UC Berkeley’s Department of Molecular and Cell Biology, working with graduate student Carolyn Phillips, has identified a key family of genes and proteins that help bring C. elegans chromosomes together during meiosis. This specialized cell division produces gametes, or sex cells, each of which has only one copy of each chromosome instead of the two copies most cells carry.
During meiosis a cell replicates and then divides twice, resulting in sperm or eggs with just one set of chromosomes each. For meiosis to work properly, corresponding chromosomes must first identify each other, then line up accurately and stay together during the recombination process. Different organisms use different methods for these critical steps; in C. elegans, the job is initiated by regions called Pairing Centers, which are found near one end of each of the worm’s six chromosome. Dernburg’s lab has been studying the role of these special regions.
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The tandem arrangement and structural similarities of the him and zim genes suggest they all arose from a common ancestor through gene duplication and subsequent selection. This inspired Dernburg and Phillips to look at similar genes in the related species C. remanei and C. briggsae. Like C. elegans, C. remanei has a total of four such genes, while C. briggsae has five. All code for zinc-finger proteins, all of which are distinct from one another.
2 responses so far ↓
Solomon // Dec 27, 2006 at 11:40 pm
Americans finally realize the try-before-you-buy works just as well with sex as it does with commodities. Rather than marrying and then shacking up with hot sex coming after the nuptuals, Americans are increasingly putting out before putting on the wedding rings.Women are just as likely as men to get it on before matrimony.
I think this is just the sign of the times. I mean, we like to test things, try them out, before making a purchase. Why should sex and marriage be any different? The stigma associated with pre-marital sex is dead. Long live free love!
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