The bizarre-looking naked mole rat is a worthy member of the genome club.
In an unflattering light, a naked mole rat looks like a wrinkly sausage with oversized teeth, legs and a tail. And given that it spends all of its extraordinarily long life short of air in dark and overcrowded underground tunnels, where it frequently eats its own excrement, an unflattering light is probably the best that a naked mole rat can hope for. Still, the best science, like love and justice, is blind, so this week the naked mole rat (Heterocephalus glaber; also known as the sand puppy or desert mole rat) joins the illustrious list of animals judged to be of sufficient significance for an analysis of their genome sequence to be published.
And what an animal it is. Unfortunately, the research paper that describes its genetic insides, published online by Nature this week (E. B. Kim et al. Nature doi:10.1038/nature10533; 2011), finds no room to feature a clear image of its extraordinary outsides. So those readers unfamiliar with this bizarre burrowing rodent native to parts of east Africa are highly recommended to look up its image on the Internet. See what we mean about the teeth?
And there's more: the mouse-sized creature is one of only two mammals known to live in ant- and termite-style eusocial colonies (the other being the Damaraland mole rat). A naked mole rat queen suppresses the sexual maturity of her subordinates, and on a royal death, the female who wins the fight to take the queen's place must stretch herself to pup-bearing size. At length, she is joined by a select few breeding males, while the other members of the colony — sterile workers — dedicate their days to the search for food and to digging and defending tunnels. Should it need to, a naked mole rat soldier can shuffle backwards as fast as its little feet normally carry it forwards.
The creature is certainly an interesting curiosity, but in these cash-strapped times, why invest in the secrets of its genome?
The naked mole rat is one of Mother Nature's great survivors. The busy underground lairs in which the animals live almost always run low on oxygen and high on carbon dioxide. Steady subterranean temperatures have sapped the creatures' ability to regulate their body temperature. Yet what they sacrifice in quality of life they more than make up for in extraordinary quantity. Comfortably the longest-living rodent, naked mole rats can live for more than 30 years. They seem impervious to cancer and do not feel some types of pain.
All of which means that the frankly ugly naked mole rat could prove a sight for sore eyes in the biomedical community. The information published on its genome and transcriptome has already revealed patterns of gene expression different from those in humans, mice and rats, and this may underlie its longevity. With further study, mechanisms of ageing, genetic regulation of lifespan, adaption to extreme environments, low-oxygen tolerance, cancer resistance, sexual development and hormonal regulation are up for grabs.
As those reporting the genome sequence say, it provides a “rich resource that can be mined in numerous ways to uncover the molecular bases for the extraordinary traits of this most unusual mammal”. And did we mention the teeth?