PDA

View Full Version : Ugly rat does amazing tricks


antiquity
08-11-2002, 08:49 PM
Location: Sunday 11 Aug 2002 > Cape news

Ugly rat does amazing tricks

KAREN VAN ROOYENA CAPE Town zoologist hopes that people with spinal injuries may be helped by his research into the odd-looking naked mole-rat, known as the "ugliest mammal on earth".

Dr Justin O'Riain , a senior lecturer in zoology at the University of Cape Town, said the tiny creature , an almost hairless rodent endemic to Africa, could hold the key to understanding whether spinal c ords could regenerate .

His previous mole-rat research concluded that the tiny creature was able to elongate its vertebrae when it prepared to reproduce - earning itself a reputation as a "biological rule-breaker".

O'Riain said they were the only mammals in which the breeders became physically specialised for reproduction, a process otherwise seen in insect societies such as ants and termites.

Each mole-rat colony has only one breeding pair, and once the queen dies, one of her daughters undergoes a "remarkable bodily transformation".

"Her lumbar [lower back] vertebrae begin to lengthen so that she ends up with a very long abdomen," said O'Riain.

The bigger abdominal area allows for a bigger litter.

O'Riain and his colleagues are now trying to determine whether the lengthening of the vertebral column is accompanied by growth of the spinal cord.

"If this is the case, then we have shown that a mammal is capable of growing new spinal cord tissues in adulthood in response to hormonal changes," said O'Riain, who is working with the university's medical school.

"The medical benefits of this to spinal cord injuries could be very important."
The mole-rats are also different from other mammals because:

They are cold-blooded, having lost the ability to regulate their own body temperature, which is a defining characteristic of mammals; and
They routinely in-breed with few of the normal problems, such as deformed or sterile offspring, normally associated with mating with close relatives.

O'Riain recently won a President's Award from the National Research Foundation for his mole-rat research.

He was also offered a position at a prestigious university in Paris, but his passion for the outdoors and sport surpassed the promise of a "fantastic job".
"I was in Paris and it's such a concrete jungle," said O'Riain.

He always knew he wanted to work with animals, but he was hooked after seeing the mole-rats for the first time.

"I was struck by what an amazing quirk of nature they are."

vgrafen
08-11-2002, 11:13 PM
You never cease to amaze me with your timely and always excellent posts, one after the other. Good news, and great job!

vgrafen

Wise Young
08-12-2002, 05:50 AM
It might be worthwhile pointing out that many mammals have elongated and specialized vertebral segments. The giraffe is probably the best known of such animals. Although a giraffe can easily be 15-20 feet tall, it has the same number of vertebral segments as we do. Its cervical segments, in particular, are very long. Another example is the whale which may exceed 100 feet in length. So, the suggestion that this rat is the only mammal in the world that has lengthened vertebral segments to accomodate specialized evolutionary needs is an example of breathless and inaccurate journalism. On the other hand, this is a very interesting example of a vertebrate that elongates its spine in adulthood. Presumably, the spinal cord is being stretched in the process of that growth. What would be of particular interest is what specific hormones are involved that results in the hypertrophy and elongation of a vertebral segment. Wise.

alan
08-12-2002, 07:28 PM
Dr. Young, the impression I got from the article was that the breeder mole rat vertebrae (and possibly spinal cord) further increased in size after it had reached adult proportions, apparently in response to hormones, which would seem to be different from the normal growth process of a giraffe, whale, or human. Was I off base?

Wise Young
08-13-2002, 02:49 AM
Alan, you are correct. This animal indeed appears to be able to elongate the spinal column as an adult in response to hormonal signals. On the other hand, a baby giraffe is able to walk and run within hours after birth and its spinal cord continues to grow in length and size for years. Likewise, a baby whale may be 5-10 feet long at birth and is able to swim but may grow to over a hundred feet in length. In both cases, the animals clearly have spinal connections that enable complex motor activities but the spinal cord continues to elongate and often by many times its original length. I am not sure that the finding of an animal that has a 20-30% elongation of the cord in adulthood represents such a dramatic finding. Wise.

[This message was edited by Wise Young on Aug 13, 2002 at 04:58 AM.]