ABSTRACT
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.
ABSTRACT
Zamzam water is the most frequently used drinking water by millions of people in Saudi Arabia. It is carried all the time by millions of pilgrims to their home countries as gifts to close and near relatives and friends. Safety of constituents of Zamzam water is a vital health topic. British Broadcasting Corporation (BBC) raised many health concerns regarding the high serum arsenic and nitrate contents in Zamzam water that may cause cancer. It is role of scientific research to present scientific facts to relieve such concerns. Arsenic is a carcinogen while nitrate causes methemogloinemia that affect oxygen carriage by haemoglobin. An ethical committee approval was obtained. Eighteen white albino mice (40-45 g) were used in this study. Three experimental groups were allocated (six mice per group): tap water group, distilled water group and Zamzam water group. Our data revealed that Zamzam water exerts tissue-protective effects that contradict malignancy. Our data proved that Zamzam water is pathogen-free causing no bacterial growth on CLED agar colonies. Zamzam water consumption for three consecutive months in mice was quite safe for the general health and significantly decreased serum uric acid (p < 0.05) (possibly due to Zamzam-induced urine alkalinisation facilitating uric acid excretion). Regular Zamzam water consumption significantly decreased serum cholesterol (p < 0.05) and serum triglycerides (p < 0.05). Hypolipidemic effects of Zamzam water may be due to its high mineral content facilitating increased lipids metabolism. Our data confirmed safety of prolonged use of Zamzam water comparable to other drinking water types regarding the metabolic and synthetic functions of the liver. Nitrates in Zamzam water are thought to be an original constituent that may be useful (exerting vasodilation, antithrombotic, and immunoregulatory effects) and not harmless. This may occur due to high Zamzam content of calcium, magnesium and selenium. Histologically, our data confirmed that Zamzam water was quite safe to renal parenchyma and comparable to other types of drinking water. In conclusion, health concerns raised by BBC regarding Zamzam water safety were a good chance for fruitful scientific research investigations that confirmed safety and beneficial effects of Zamzam water for human health.
