Researchers have sequenced the genome of the human skin mite Demodex folliculorum to find it has a reduced genome, Gizmodo reports. It adds that the team further characterized the mite's physiology to find, contrary to what some have thought, that it does have an anus.
According to Gizmodo, some scientists had thought fecal matter accumulated within D. folliculorum over their lifespan of a few weeks and was released upon their deaths. But study author Alejandra Perotti from the University of Reading tells it that she and her colleagues found that to not be true.
As she and her colleagues report in Molecular Biology and Evolution, they also sequenced the mite to find that it has a much diminished genome and a reduction in cell number, which they argue reflects a transition from being an obligate parasite to an obligate symbiont. They found, for instance, that each of the three mite segments with walking legs have a single uninucleate muscle cell.
"By the point at which Demodex enters a stable, nonpathological relationship with humans involving vertical transmission, extinction as a mathematical and statistical consequence might have already been determined," the researchers note.