Genetic changes in parasitic mites that live and mate on people’s faces may harm the host, a new study finds.
These organisms, measuring 0.3 millimeters in length, are likely at risk of extinction due to inbreeding and loss of genes, findings published in the journal Molecular biology and evolution showed.
The study looked at Demodex folliculorum, a small parasitic mite found on eyelashes, eyebrows, or near the nose. The other known variety of facial mite is: Demodex brevis, but it was not covered in the study.
“Demodex folliculorum” is the dominant mite species, certainly for Europe. demodex brevis comes after that,” said Henk Braig, co-author of the study from Bangor University and the National University of San Juan . With both feet on the ground (DTE).
Microscopic view of a Demodex folliculorum mite on the skin. Source: University of Reading
As much as According to estimates by others, an estimated 50-100 percent of adults are carriers of these mites studies†
Despite their prevalence, not much is known about them. For example, researchers don’t understand why they are nocturnal or how they evolved over the years.
Braig and his colleagues wanted to bridge this knowledge gap by building the DNA of Demodex folliculorum†
These parasites have adapted to live sheltered lives in skin pores, Alejandra Perotti, an associate professor of invertebrate biology at the University of Reading who led the study, said in a statement.
This comes at a cost: The researchers recorded changes in the DNA, which resulted in unusual body characteristics and behaviors.
The species has become extremely simple, the findings show. They survive on the minimal supply of protein — the lowest of related species, the researchers emphasized.
Inbreeding does not create new genes, they emphasized.
These mites infect new hosts vertically and pass from parent to offspring. This transmission route prevents them from mixing with fellow mites living on unrelated human hosts. Without them, they lose a chance at acquiring a newer variety of genes, the experts said in their study.
“Demodex is becoming less contagious,” Braig said.
Another notable feature was a drop in cell number. The researchers found that younger mites have more cells than adults.
This suggests that the mites evolve from parasites to symbionts, establishing a mutually beneficial relationship with their human hosts, the report said.
They are parasites only for a few people and in at least one case because of a mutation in the human genome of these people. In many cases where people have problems with Demodex, it is a result of other problems, not the cause.
“Demodex has a beneficial function in humans: to keep the pores clean,” the expert added. These organisms feed on sebum, an oily, waxy substance produced by the human body, researchers said.
Furthermore, these organisms lose some of the genes that produce repair enzymes. “If this continues, the genome will degrade more and more,” Braig said. This puts them at risk of possible extinction, the expert added.
Loss of genes may also explain why the mites remain active at night. Genes that sustain them during the day have disappeared, the findings show.
A change in gene arrangement led to strange mating behavior, the study noted.
Men’s penises stick up from the front of the body, the researchers said. This arrangement suggests that they should position themselves below the female during mating, they explained.
a 2015 analysis suggested that demodex folliculorum could shed light on ancient human migrations. Some mites are better equipped to survive and reproduce on hosts from certain geographic regions, according to the study.
The researchers hope the number of mites on the human body and estimate population size.
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