Genome study finds mites that live and breed on your face have anus

Illustration of Demodex follicle.

an illustration Demodex mites.
photo: Shutterstock (Shutterstock)

Scientists have finally uncovered the genetic secret of man’s most comfortable roommate: Demodex, also known as skin mites. Among other things, the findings confirmed that the mites did have anus, contrary to previous speculation. They also show that microscopic animals may not be as potentially harmful as is commonly believed, and that they are evolving into interdependent symbionts that could offer us some benefits.

D. follicles actually one of two mite species call us home, and Demodex Both species are arachnids — more closely related to ticks than spiders — but D. follicles Mites usually live (and mate) on our faces. These stubby, worm-like critters can live for two to three weeks, embedded in our pores and clinging to our hair follicles, feeding primarily on our sebum, the oily substance our body provides to protect and moisturize our skin.

While almost everyone in the world has their own mite collection, there’s still a lot we don’t know about them.But in a new study post In the journal Molecular Biology and Evolution on Tuesday, researchers in Europe said they have now D. follicles– This achievement may answer some lingering questions about their inner workings.

For example, some researchers believe that these mites do not have anus. The theory is that without an anus, their feces only accumulate in their bodies during their short lives, and are only released immediately when they die. Some have also speculated that too many mites can lead to a skin condition called rosacea, which may be caused by bacteria released from exploding feces when the mites die. Other studies have challenged this claim, though, and the researchers behind the new study say they have confirmed that the mites do have anus.

Study author Alejandra Perotti, a researcher at the University of Reading in the United Kingdom, points out that people with rosacea and other skin conditions have more mites in their bodies, which are likely the result of the disease rather than its actual cause. If the mites don’t leave behind a lot of poo when they die, it’s less clear how they can make us sick.Other research, for what it’s worth, has continue Find the link between mites and rosacea, even though they may be just one of them many triggers involves.

“It’s easier and quicker to blame the mites,” she said in an email to Gizmodo.

Other findings from the team suggest that, genetically, the mites have evolved to be very lazy, as they ride their wagons on humans. They have a remarkably simple genome compared to other related species, and they seem to require minimal cells and proteins to survive (their legs and even each leg are powered by a single muscle cell). They’ve lost their ability to survive UV light, which explains why they huddle deep in our pores, only move and mate at night, and they don’t seem to produce their own melatonin like many animals anymore— Instead, they seem to sneak up on us. They are also often passed from mother to child through breastfeeding, meaning the genetic diversity of the population is relatively low. And their lack of natural enemies, host competition and generally cryptic presence suggests that the mites will only lose more genes over time.

The researchers speculate that these trends could one day lead to D. follicles The mites, they say, are a distinct entity—a process observed in bacteria but never in animals. Eventually, the mites may no longer live on our skin like parasites, but become fully internal symbionts. If so, then we may be seeing this shift happening now, although it most likely won’t be complete for a long time.

Regardless of the future fate of these mites, scientists say they may be doing something good for us right now. They may help remove excess dead cells and other substances from the skin, for example, at least if their populations are controlled. Perotti also hopes their study will give people “a proper understanding of these permanent partners, who have long been blamed for our skin problems.”

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