Fwd: trojan gene

[Ken Medlin <dev-plan@moscow.com>]

Subject:     trojan gene
Sent:        12/9/19 4:31 AM
Received:    12/4/99 11:21 PM
From:        K.H. von Kaufmann, kenn@freenet.co.uk
Reply-To:    general@lists.holisticmanagement.org
To:          general@lists.holisticmanagement.org

CHM-general,     [Note to Visionaries: At the risk of 'overload', but in the spirit of Bill London's praise of this community medium, I'm sharing this post from a member of the  Center for Holistic Management of Albuquerque, NM, giving info. from recent research and experiences with biotic-genetic technologies. We in the Palouse are directly affected by the biological-botanical modifications being imposed on natural life forms -- at our human peril? So our communities must eventually take a position on these matters, which incidentally inspired much of the WTO disturbances in Seattle last week. We are involved, whether we choose to be or not. Our two universities are heavily subsidized by orgs. engaged in genetic modifications; hence, so are you and I.  Ken M.]

--------------------------------------
Extinction point
http://www.newscientist.com/ns/19991204/newsstory1.html

It only takes one fish with the Trojan gene to invade a population and wipe
it out

A SINGLE genetically modified fish could turn Darwinian evolution upside
down and wipe out local populations of the species if released into the
wild, biologists warn. They add that other organisms could face the same
risk from transgenic relatives. 

William Muir and Richard Howard of Purdue University in West Lafayette,
Indiana, made the discovery while modelling ecological risks associated
with genetically modified organisms (GMOs). They have dubbed their idea the
"Trojan gene" hypothesis. "This resembles the Trojan horse," says Muir. "It
gets into the population looking like something good and it ends up
destroying the population.". 

The researchers studied fish carrying the human growth hormone gene hGH,
which increases growth rate and final size. Biologists in the US and
Britain are experimenting with salmon engineered in a similar way, although
no one has yet begun commercial production. 

Muir and Howard included hGH in embryos of a fish called the Japanese
medaka (Oryzias latipes), a common aquarium fish that is widely used in
research. They found that modified individuals became sexually mature
faster than normal fish and produced more eggs. 

Other experiments using non-modified fish also showed that larger males
attracted four times as many mates as their smaller rivals. This effect is
also known in salmon. Muir predicts that bigger, engineered fish would
enjoy the same advantages. So the hGH gene would quickly spread through a
fish population. 

But Muir and Howard also found that only two-thirds of engineered medaka
survived to reproductive age compared with wild medakas. So the spread of
the growth hormone gene could make populations dwindle and eventually
become extinct. 

To quantify this, the researchers plugged their results into a computer
model to find out what would happen if 60 transgenic individuals joined a
wild population of 60 000 fish. The population became extinct within just
40 generations. Even a single transgenic animal could have the same effect,
they found, although extinction would take longer. 

"You have the very strange situation where the least fit individual in the
population is getting all the matings--this is the reverse of Darwin's
model," says Muir. "The sexual selection drives the gene into the
population and the reduced viability drives the population to extinction."
The researchers say their results are the first evidence that GMOs could
have catastrophic consequences on their own species. 

David Penman, a fish geneticist at the University of Stirling, welcomes the
discovery. But he says there is evidence that some transgenic fish modified
with growth hormone have reduced sperm production and mating success. "If
large males tend to mate with large females, this would often result in
matings between transgenics," he adds. This would decrease rather than
increase the spread of the gene. 

But John Beringer of Bristol University, a former chairman of the British
committee that advises the government on GMOs, says the research is a
warning. "It would make it very difficult for anyone at the moment to
approve the release of GM fish carrying growth hormone," he says. "I would
have to give a great deal of consideration about whether that's an
intelligent route to go down." 

Muir says that the model may prove an invaluable tool in assessing the
dangers of GMOs. He hopes to test its predictions in tightly controlled
fish farm ponds.

Source: Proceedings of the National Academy of Sciences (vol 96, p 13 853)

Matt Walker

>From New Scientist, 4 December 1999
© New Scientist
--------------------------------------
Also in this issue of NS is an item on Bt from GM maize leaking into the
soil and persisting for weeks unexpectedly.

Kenn

---------------------------------------------------------------------
To subscribe to general@lists.holisticmanagement.org, send email to:
  general-subscribe@lists.holisticmanagement.org
To unsubscribe to general@lists.holisticmanagement.org, send email to:
  general-unsubscribe@lists.holisticmanagement.org
For more help, send mail to:
  general-help@lists.holisticmanagement.org

The Allan Savory Center for Holistic Management
1010 Tijeras Ave NW, Albuquerque, NM 87102 USA
505.842.5252-ph, 505.843.7900-fax
SavoryCenter@HolisticManagement.org
www.HolisticManagement.org



------------------------
William K. Medlin
Dev-plan associates
930 Kenneth Street
Moscow ID 83843
208/892-0148
dev-plan@moscow.com