The secret life of mites on the skin of our face

Image showing Demodex folliculorum mite on skin under Hirox microscope. Credit: Reading University

Microscopic mites, which live in human pores and mate on our faces at night, are becoming so simplified organisms due to their unusual lifestyles that they may soon become one with humans, according to new research.

Ticks are transmitted at birth and are carried by almost everyone, and in adults the maximum number of pores is growing. They are about 0.3 mm long, occur in facial hair follicles and nipples, including the eyelashes, and eat fat that is naturally secreted by the cells in the pores. They are active at night and move between follicles to mate.

The first genomic sequencing study of D. folliculorum mites showed that their isolated life and consequent inbreeding resulted in the shedding of unwanted genes and cells and the transition from external parasites to internal symbionts.

Dr. Alejandra Perotti, an associate professor of invertebrate biology at the University of Reading, who led the study, said: These changes in their DNA have led to abnormal features and behavior in the body. “






The Demodex folliculorum mite is examined under a microscope. Credit: Reading University

In-depth study of Demodex folliculorum DNA:

  • Because of their isolated lives, exposure to external threats, competition to infect their hosts, and lack of contact with other mites with other genes, genetic reduction has led them to become very simple creatures with small legs that work with 3 single-celled muscles. They can live with a minimal repertoire of proteins – this and the minimum number of related species.
  • Decreased levels of this gene are also a factor in their nocturnal behavior. Mites are not protected from UV light and have lost a gene that can wake animals during the day. They also failed to produce melatonin, a compound that activates small invertebrates at night, but they use melatonin, which is secreted from human skin, to mate throughout the night.
  • Their unique gene structure also leads to the unusual mating habits of mites. Their reproductive organs are advanced, and the male has a penis that protrudes above the front of the body, meaning that during mating, they must be located under the female, and both must adhere to the human hair and multiply.
  • One of their genes is inverted, giving them a special structure of oral appendages that come out specifically to collect food. This will help them to survive in their youth.
  • Mites have a much larger number of cells at a younger age than in adulthood. This contradicts the earlier hypothesis that parasites reduce the number of cells in animals at the beginning of development. Researchers say that this is the first step in making ticks symbiotic.
  • The lack of influence of potential pairs to add new genes to their offspring may have led to an evolutionary deadlock and the possible extinction of mites. This has previously been observed in bacteria living inside cells, but never in animals.
  • Some researchers thought that mites did not have an anus, so they had to collect their feces for the rest of their lives before they could cause inflammation of the skin when they died. But a new study confirmed that they had anus, so they were unfairly blamed for many skin diseases.
  • The secret life of mites on the skin of our face

    The picture shows the abnormally located penis of Demodex folliculorum mite. Credit: Reading University

  • The secret life of mites on the skin of our face

    Microscopic image of the posterior end of the rectum of Demodex folliculorum mite. Some people have previously misdiagnosed the presence of anus in this tick, but this study confirmed its existence. Credit: Reading University

The study was conducted by the University of Bangor and the University of Reading in collaboration with the University of Valencia, the University of Vienna and the National University of San Juan. It was published in a magazine Molecular biology and evolution.

Dr. Hank Braig, co-author of Bangor University and San Juan National University, said: “Tips have been blamed for a lot of things.


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More information:
Gilbert Smith et al., Human follicular mites: The symbiotic transformation of ectoparasites, Molecular biology and evolution (2022). DOI: 10.1093 / molbev / msac125

Submitted by Reading University

Quote: The secret life of ticks on the skin of our face (June 21, 2022) Retrieved June 22, 2022 https://phys.org/news/2022-06-secret-mites-skin.html.

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