Snippets Jan 16

This worm lost a quarter of its DNA

Inspecting the tiny roundworms Caenorhabditis briggsae (C briggsae) and Caenorhabditis nigoni (C nigoni) through a microscope, youd have trouble telling them apart. Both are about a millimetre long and transparent. The key distinction between the two nematodes is their sex lives. Sex in C nigoni takes place between a male and a female. But only a small minority of C briggsae are males. The rest are hermaphroditic females that reproduce by self-fertilising or selfing. This sexual switch may have caused profound changes at the genetic level for C briggsae. In a study published in the journal Science, biologists reported that C briggsae lost thousands of genes – a staggering quarter of its genome – since it diverged from C nigoni a million years ago.

In their study, the biologists compared C briggsae and C nigoni, and discovered that C briggsae has about 7,000 fewer genes. Digging into a specific example of what C briggsae lost when it dumped all those genes, the researchers studied male secreted short genes, which have been found in all studied Caenorhabditis species except those with selfing hermaphrodites.

4D physics in two dimensions

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