Human follicular mites: Ectoparasites becoming symbionts.
Por:
Smith G, Manzano Marín A, Reyes-Prieto M, Ribeiro Antunes CS, Ashworth V, Goselle ON, Jan AAA, Moya A, Latorre A, Perotti MA and Braig HR
Publicada:
2 jun 2022
Ahead of Print:
21 jun 2022
Resumen:
Most humans carry mites in the hair follicles of their skin for their entire lives. Follicular mites are the only metazoans tha continuously live on humans. We propose that Demodex folliculorum (Acari) represents a transitional stage from a host-injuring obligate parasite to an obligate symbiont. Here, we describe the profound impact of this transition on the genome and physiology of the mite. Genome sequencing revealed that the permanent host association of D. folliculorum led to an extensive genome reduction through relaxed selection and genetic drift, resulting in the smallest number of protein-coding genes yet identified among panarthropods. Confocal microscopy revealed that this gene loss coincided with an extreme reduction in the number of cells. Single uninucleate muscle cells are sufficient to operate each of the three segments that form each walking leg. While it has been assumed that the reduction of the cell number in parasites starts early in development, we identified a greater total number of cells in the last developmental stage (nymph) than in the terminal adult stage, suggesting that reduction starts at the adult or ultimate stage of development. This is the first evolutionary step in an arthropod species adopting a reductive, parasitic or endosymbiotic lifestyle. Somatic nuclei show underreplication at the diploid stage. Novel eye structures or photoreceptors as well as a unique human host melatonin-guided day/night rhythm are proposed for the first time. The loss of DNA repair genes coupled with extreme endogamy might have set this mite species on an evolutionary dead-end trajectory.
Filiaciones:
Smith G:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Manzano Marín A:
Centre for Microbiology and Environmental Systems Science (CMESS), University of Vienna, Vienna, Austria
:
Institute of Integrative Systems Biology (I2Sysbio), Universitat de València and Spanish Research Concil (CSIC), València, Spain
Foundation for the promotion of health and biomedical research of the Valencian Community (FISABIO), Valencia, Spain
Ribeiro Antunes CS:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Present address: School of Biological Sciences, University of Reading, Reading, United Kingdom
Ashworth V:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Goselle ON:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Present address: Applied Entomology and Parasitology Unit, Department of Zoology, University of Jos, Jos, Nigeria
Jan AAA:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Present address: Laboratory and Blood Bank, King Fahad General Hospital, Al-Madinah Al-Munawwarah, Saudi Arabia
:
Institute of Integrative Systems Biology (I2Sysbio), Universitat de València and Spanish Research Concil (CSIC), València, Spain
Foundation for the promotion of health and biomedical research of the Valencian Community (FISABIO), Valencia, Spain
Center for Networked Biomedical Research in Epidemiology and Public Health (CIBEResp), Madrid, Spain
:
Institute of Integrative Systems Biology (I2Sysbio), Universitat de València and Spanish Research Concil (CSIC), València, Spain
Foundation for the promotion of health and biomedical research of the Valencian Community (FISABIO), Valencia, Spain
Center for Networked Biomedical Research in Epidemiology and Public Health (CIBEResp), Madrid, Sain
Perotti MA:
School of Biological Sciences, University of Reading, Reading, United Kingdom
Braig HR:
School of Natural Sciences, Bangor University, Bangor, Wales, United Kingdom
Institute and Museum of Natural Sciences, National University of San Juan, Argentina
gold, Green Published
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