Then there is the bizarre
star-nosed mole, Condylura cristata, the only tentacled mammal, whose
nose contains 30,000 microscopic sensory organs and which probably
“sees” the world through touch. Or the mole-like Pyrenean desman, which
looks like it has been put together out of random components — part rat,
part mole, part shrew and part platypus. But surely the award must go
to the mysterious and curiously engaging naked mole rat, Heterocephalus
glaber, which is so weird in every respect that it resembles a creature
from outer space.
Not only is it so unlike any
other mammal that it almost seems to deserve its own category, but
scientists now believe it may hold the key to curing cancer - and even,
as Prof Steve Jones has mentioned before on these pages, extending the
human life span. Uncommonly among mammals, mole rats do not get cancer,
and last week, scientists announced that they have finally discovered
why. They hope the “gloop” that they have identified in the animal
could, in due time, form the basis of a host of new medicines to treat
not only cancer but diseases ranging from atherosclerosis to arthritis.
It seems odd that the naked
mole rat could spark any kind of medical revolution. In terms of its
ecology and physiology, these animals are outliers. Naked mole rats are
small, almost hairless rodents, about four inches long, that live in
eastern and southern Africa. They are the only known “eusocial” mammal;
the structure of a mole rat colony is identical to that of hive insects
such as bees, and other arthropods such as termites.
There is one female, a queen,
who mates with a handful of fertile males; the rest of the colony,
which may number 80 or so, consists of sterile “workers”. That is only
the start of the weirdness. They are, as their name suggests, naked (or
nearly so — the odd whisker sprouts from their faces). They can run
backwards as fast as forwards, and can manipulate their goofy incisor
teeth individually, like chopsticks.
Unlike all other mammals,
naked mole rats are not truly warm-blooded: they regulate their
temperature in a crude fashion, more like a lizard than, say, a mouse.
The oddities continue. Mole rats, which live off underground roots and
tubers, appear not be able to feel pain, at least on their skin. The
pain receptors found in all mammals — called nociceptors — are there,
but they appear to be turned off, as German scientists found when they
studied the way the receptors reacted to being immersed in corrosive
chemicals. Douse a naked mole rat in acid, and it will not flinch. (It
is finding out how these nociceptors operate that could be the key to
new treatments for arthritis.) Mole rats can also survive
extraordinarily high degrees of carbon dioxide, which builds up in their
tunnels to levels that would kill a human in minutes.
In terms of
cancer, numerous studies have failed to find a single tumour in the
thousands of individuals sampled. Finally, there is the curious fact
that these little rodents live for around 30 years — 10 to 20 times the
life span of relatives such as rats and mice. For most species, there is
a rough correlation between size and longevity. Big animals, the theory
goes, tend to live longer because they are less likely to die quickly
of cold or starvation or be eaten. Thus genes that confer health into
old age can be passed on. That is why whales and giant tortoises live
longer than shrews and mice. Mole rats should live a few years at most,
but instead they can outlast chimpanzees. It is, however, that
resistance to cancer — which is probably related to their longevity —
that has proved the most intriguing puzzle. Now, Vera Gorbunova and
colleagues at the University of Rochester in New York have identified a
polysaccharide — a gloopy, sugar-based natural polymer - found in naked
mole rat cells that stops tumours growing. The scientists, whose study
was published in the current edition of Nature, suggest that the finding
“opens new avenues for cancer prevention and life-extension”.
The chemical, called
high-molecular-mass hyaluronan (HMM-HA), acts as a kind of lubricant,
allowing mole rats to squeeze their Plasticine-like bodies through the
smallest and most convoluted tunnels:
“They can virtually turn
somersaults in their skin,” Chris Faulks, a scientist at Queen Mary,
University of London said this week. It seems, therefore, that the
ability of HMM-HA to confer cancer resistance was a happy evolutionary
accident. And one day, it may be possible to engineer the ability to
produce HMM-MA in human tissues — hopefully without the side effect, as
Dr Faulks says, of making us all end up looking like naked mole rats.
Of course, this isn’t the
first time that an extraordinary feature in an animal has been seized on
as a possible cure for human ailments. While the thesis of Dr I.
William Lane’s Sharks Don’t Get Cancer, published in 1992, is now widely
held to be incorrect, crocodiles have an extraordinary ability to fight
off bacterial infections: injured crocs have been in bacterially
infested swamps, blood pouring out of open wounds, yet remained
infection-free. Then there is one of the most intriguing findings of
recent decades — that chimpanzees do not get Aids, despite being
susceptible to the same group of retroviruses as humans. In fact, it is
now believed that the Aids epidemic started when the virus jumped
species from ape to human, probably in the forests of west Africa around
100 years ago, as a result of a hunting accident or by consumption of
ape meat.
While chimps can get infected
by the virus, they do not go on to suffer the disease: the reason why
may lurk in the one per cent of the chimp genome that differs from ours.
That we can solve medical mysteries by looking at our close cousins is
not surprising; yet finding that an animal so weird, and so ugly, as the
naked mole rat could one day lead to a cure for cancer seems utterly
bizarre. However, this creature has gained the respect of an increasing
number of scientists: robust to the point of near-indestructibility,
living in perfect conflict-free communes, immune to pain and capable of
spending years underground at a time, this meekest of animals could,
should the apocalypse strike, be in pole position to inherit the Earth.
I'm from Fresno California. i don't really have much to say but to tell the world about Dr. Sam no how he cured me from cancer. A friend told me about the good work that Dr. Sam has done and she gave me his contact +1 (213) 349-2159 and i give a try that is now a testimony today. World can't even explain my feelings. God bless the good work of Dr.Sam. You can reach Dr Sam on his Whats app number: +1 (213) 349-2159.
ReplyDelete