Headline: Transgenic Fish Could Threaten Wild Populations
Wire Service: OTC (COMTEX Newswire)
Date: Tue, Feb 1, 2000
WEST LAFAYETTE, IN, Feb 01, 2000 (INTERNET WIRE via COMTEX) -- Purdue
University researchers have found that releasing a transgenic fish to
the wild could damage native populations even to the point of
extinction.
A transgenic organism is one that contains genes from another
species. The Purdue research is part of an effort by Purdue and the
U.S. Department of Agriculture to assess the risks and benefits of
biotechnology and its products, such as genetically modified fish. The
study was published in November in the Proceedings of the National
Academy of Science.
Purdue animal scientist Bill Muir and biologist Rick Howard used
minute Japanese fish called medaka to examine what would happen if male
medakas genetically modified with growth hormone from Atlantic salmon
were introduced to a population of unmodified fish. The research was
conducted in banks of aquariums in a laboratory setting.
The results warn that transgenic fish could present a significant
threat to native wildlife. "Transgenic fish are typically larger than
the native stock, and that can confer an advantage in attracting mates"
Muir says. "If, as in our experiments, the genetic change also reduces
the offspring's ability to survive, a transgenic animal could bring a
wild population to extinction in 40 generations."
Extinction results from a phenomenon that Muir and Howard call the
"Trojan gene hypothesis." By basing their mate selection on size rather
than fitness, medaka females choose the larger, genetically modified
but genetically inferior medaka, thus inviting the hidden risk of
extinction.
The transgenic medaka were produced by inserting a gene construct
consisting of the human growth hormone driven by the salmon growth
promoter into medaka. The viability of groups of modified and
conventional fish were measured at three days of age, and 30 percent
fewer transgenic fish survived to that age. The researchers calculated
that large males had a four-fold mating advantage, based on
observations of wild-type medaka. Computer models then were used to
predict the consequences of the transgenic mating advantage combined
with the reduced
viability of the young.
The study represents scientists policing science, Muir says. "I
hope people understand that scientists are investigating the risks of
biotechnology as well as the benefits, so decisions can be made with as
much information as possible. It's important to understand the risks so
they can be addressed."
Muir also cautions that the results of his laboratory study should
be interpreted conservatively. "The study does confirm there are
significant risks to natural animal populations associated with the
release of transgenic animals. We assumed a consistent environment with
only one variable ? sexual preference for size coupled with low life
expectancy for the transgenic. The natural world is not nearly as
orderly, and genetic background changes could negate the Trojan gene,"
he says.
The dominance of sexual preference over Charles Darwin's classic
theory of survival of the fittest is not unknown to wildlife specialists
and geneticists. Muir likes to use the example of the male bird of
paradise with its long swells of gloriously colored plumage as an
example: "The male bird of paradise with the longest, thickest tail
attracts the most females. Subsequent offspring also exhibit the long
tail and also compete well for females. Unfortunately, the birds with
the biggest tails also have the biggest problem escaping predators who
appreciate large birds pinned in place by their plumage. Obviously the
bird with the most sex appeal is the also the worst choice as a fit
mate. Not unlike high school, some might say."
The researchers' next goal is to replicate the study with larger fish
of economic importance in a bigger environment. They're looking for an
indoor swimming pool where they can raise tilapia and check the results
of the medaka study.
Copyright 2000 Internet Wire, All rights reserved.
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
Archive: http://www.mail-archive.com/[email protected]/
