X-Message-Number: 29483
Date: Thu, 03 May 2007 12:44:30 -0400
From: Keith Henson <>
Subject: Re: Gene Discovered

Slightly more detail in this article than the one on the same subject 
posted yesterday by flavonoid.  Cool stuff.  I do appreciate people posting 
such things here.  Keith

Gene clue to longevity uncovered
By Rebecca Morelle
Science reporter, BBC News

The study was carried out on nematode worms
The mystery of how eating less boosts longevity is closer to being solved.
Studies have shown that severe calorie restriction markedly extends 
lifespan in mice and many other species - but the reasons for this remained 
elusive.

But now US research on nematode worms, published in Nature, has uncovered a 
gene linked to this unusual effect.

In the future, the find could lead to drugs that mimic the consequences of 
calorie restriction but negate the need for severe fasting regimes.

Sweet-spot

The life-lengthening properties of reducing calorie intake were first 
discovered in the 1930s, when laboratory rodents fed a severely reduced 
diet were found to outlive their well-fed peers.

Since then, this effect has been observed on organisms as diverse as yeast, 
flies, worms and dogs.

The consequences for humans of cutting calorie intake by about 60% while 
maintaining levels of vital nutrients are still unclear, although this 
extreme diet has a number of followers.

Andrew Dillin, an author of the paper and an associate professor at the 
Salk Institute for Biological Studies, said: "If you reduce food too much, 
you go towards starvation and live less long. If you overeat you will 
succumb to obesity and have a short lifespan. Dietary restriction is really 
a sweet-spot between the two.

"But for 72 years, we have not known how it works."

The scientists say mammals have a similar gene to pha-4
A study using nematode worms (Caenorhabditis elegans) revealed that a gene 
called pha-4 played a key role.

The team found worms that had their pha-4 genes removed showed no enhanced 
longevity while on the restricted diet.

But they discovered that the opposite experiment - over-expressing levels 
of pha-4 in the worms - increased longevity when on the restricted diet.

"This is the first gene we have found that is absolutely essential to the 
longevity response to dietary restriction," explained Dr Dillin.

"We finally have genetic evidence to unravel the underlying molecular 
programme required for increased longevity in response to calorie 
restriction."

Feast or famine

Although the study was carried out on worms, the finding could also be 
important for other species.

Mammals, including humans, possessed genes that were highly similar to the 
pha-4 gene, explained Dr Dillin.

Eat less, live longer?

These genes play a key role in development, and then in later life in the 
regulation of glucagon, a hormone that has a major role in maintaining 
glucose levels in blood - especially during fasting.

In fact, scientists believe the life-increasing effect of dietary 
restriction may be linked to boosting chances of survival through times of 
food scarcity.

"Pha-4 may be the primordial gene to help an animal overcome stressful 
conditions to live a long time through dietary restriction conditions," 
explained Dr Dillin.

Parallels?

Scientists now plan to look at the gene in other species.

Should the longevity link also apply to humans, it could open the door to 
the development of drugs that mimic the effects of calorie restriction 
while allowing people to maintain their normal diet, the scientists said.

Professor Richard Miller of the Institute of Gerontology at the University 
of Michigan, commented: "It is really hard to guess whether the connections 
that we see between the pha-4 system and calorie restriction in worms will 
have parallels in mammals, whose repertoire of responses to various forms 
of long- and short-term food shortages are far more complex than those of 
worms.

"But the Dillin paper provides both motivation to look and also clues about 
where to look. I think it's likely to be influential, even if the 
implications for mammals do eventually turn out to be a cul-de-sac - which 
they might or might not."

Source: BBC
http://news.bbc.co.uk/2/hi/science/nature/6612411.stm  

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