Heterocephalus glaber
The naked mole rat or naked mole rat (Heterocephalus glaber), also known as the farumfer, shaved mouse or heterocephalic, is a species of hystricomorph rodent in the Bathyergidae family. It is the only species of its genus.
Naked mole rats are small subterranean rodents that live mainly in Ethiopia, Kenya and Somalia and whose most prominent visible characteristic is the lack of hair that gives them a strange appearance. In many places it is considered a pest due to its eating habits, as it feeds on roots and tubers, damaging potato crops and other vegetables.
Social Structure
Its longevity, exceptionally long among rodents of its size, is around 29 years, but its most outstanding biological characteristic is that the naked mole-rat, along with a few other batirgids, is one of only two species of known eusocial mammals, that is to say that it has a caste specialized solely in reproduction, the rest of the individuals in the colony being sterile, as occurs with some social insects such as ants, termites and bees. In their underground tunnel systems, dug by workers, mainly with their large incisors, they have common areas where they excrete and wallow to maintain the common odor of the colony. It is there that contact with the queen's urine, which is believed to contain special pheromones yet to be detected, keeps the rest of the females and most of the males in the colony sterile until the colony dies or disappears and, consequently, is relieved when his urine ceases to produce an effect. Only this leads the females to fight to the death among themselves to decide who will be her successor.
The queen has specialized vertebrae that make her longer than the rest of the females. The lower part of the dorsal spine elongates after its first or second gestation until it reaches a third more length than that of the others. A queen's litter consists of between 3 and 12 pups, although she is capable of holding up to 27 fetuses. In a normal colony, between one and three males mate with the queen while the rest of the individuals (ranging from 20 to 300, both males and females) take on the role of workers digging tunnels and foraging for food, servants tending to the queen and her progeny and soldiers who defend the tunnels from attacks by snakes, foxes, eagles and owls.
Resistance to cancer
Some studies have revealed that naked mole-rats are resistant to spontaneous cancer and experimentally induced tumorigenesis.
The explanation for the resistance of these animals to cancer may be due to one of the two protection mechanisms that have been proposed, involving contact inhibition mediated by p16lnKa4 and p27Kip1. The involvement of p16lnKa4 is unusual in that humans and mice show only p27Kip1-mediated contact inhibition. Analysis of the gene locus and transcriptome readout corresponding to the p16lnKa4 and p19Arf tumor suppressor genes. In mice the p16lnKa4 transcript consists of three exons, however the sequence similarity in the last exon is low, the presence of two stop codons in the second exon predicts a shorter protein (14kDa). Thus, it has been shown that four ankyrin repeats, however Thr69, which is a very important residue for CDK6 binding, is conserved, so that the function of the protein may be partially conserved.
The p19Arf transcript consists of two exons however four stop codons in the second exon lead to a shorter protein (10kDa).
Recent studies have shown that resistance to cancer is due to the accumulation of hyaluronic acid, more complex than that of humans and mice. When the HAS2 gene is deactivated, tumors are produced.
Pain
The naked mole rat is the only animal whose skin and cutaneous C fibers are deficient in the neuropeptide known as substance P, making these animals insensitive to certain types of pain. The intact presence of TAC1 encoding substance P has been revealed, however in this animal there is a nuclear deletion in the promoter region which is highly conserved among mammals, therefore this neurotransmitter appears to be functional but may be under unique regulation..