<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2627" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT size=4>From: <EM>New York Times</EM> 06-03-05</FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><!--StartFragment -->
<DIV class=timestamp>June 3, 2005</DIV><NYT_HEADLINE type=" "
version="1.0"></NYT_HEADLINE>
<H1>For Fruit Flies, Gene Shift Tilts Sex Orientation</H1><NYT_BYLINE type=" "
version="1.0"></NYT_BYLINE>
<DIV class=byline>By <A title="More Articles by Elisabeth Rosenthal"
onclick="javascript:s_code_linktrack('Article-Byline');"
href="http://query.nytimes.com/search/query?ppds=bylL&v1=ELISABETH%20ROSENTHAL&fdq=19960101&td=sysdate&sort=newest&ac=ELISABETH%20ROSENTHAL&inline=nyt-per">ELISABETH
ROSENTHAL</A>, <BR>International Herald Tribune </DIV><NYT_TEXT></NYT_TEXT>
<DIV id=articleBody>
<P>When the genetically altered fruit fly was released into the observation
chamber, it did what these breeders par excellence tend to do. It pursued a
waiting virgin female. It gently tapped the girl with its leg, played her a song
(using wings as instruments) and, only then, dared to lick her - all part of
standard fruit fly seduction. </P>
<P>The observing scientist looked with disbelief at the show, for the suitor in
this case was not a male, but a female that researchers had artificially endowed
with a single male-type gene. </P>
<P>That one gene, the researchers are announcing today in the journal <A
href="http://www.cell.com/" target=new>Cell</A>, is apparently by itself enough
to create patterns of sexual behavior - a kind of master sexual gene that
normally exists in two distinct male and female variants. </P>
<P>In a series of experiments, the researchers found that females given the male
variant of the gene acted exactly like males in courtship, madly pursuing other
females. Males that were artificially given the female version of the gene
became more passive and turned their sexual attention to other males. </P>
<P>"We have shown that a single gene in the fruit fly is sufficient to determine
all aspects of the flies' sexual orientation and behavior," said the paper's
lead author, Dr. Barry Dickson, senior scientist at the Institute of Molecular
Biotechnology at the Austrian Academy of Sciences in Vienna. "It's very
surprising.</P>
<P>"What it tells us is that instinctive behaviors can be specified by genetic
programs, just like the morphologic development of an organ or a nose." </P>
<P>The results are certain to prove influential in debates about whether genes
or environment determine who we are, how we act and, especially, our sexual
orientation, although it is not clear now if there is a similar master sexual
gene for humans.</P>
<P>Still, experts said they were both awed and shocked by the findings. "The
results are so clean and compelling, the whole field of the genetic roots of
behavior is moved forward tremendously by this work," said Dr. Michael Weiss,
chairman of the department of biochemistry at Case Western Reserve University.
"Hopefully this will take the discussion about sexual preferences out of the
realm of morality and put it in the realm of science." </P>
<P>He added: "I never chose to be heterosexual; it just happened. But humans are
complicated. With the flies we can see in a simple and elegant way how a gene
can influence and determine behavior." </P>
<P>The finding supports scientific evidence accumulating over the past decade
that sexual orientation may be innately programmed into the brains of men and
women. Equally intriguing, the researchers say, is the possibility that a number
of behaviors - hitting back when feeling threatened, fleeing when scared or
laughing when amused - may also be programmed into human brains, a product of
genetic heritage. </P>
<P>"This is a first - a superb demonstration that a single gene can serve as a
switch for complex behaviors," said Dr. Gero Miesenboeck, a professor of cell
biology at Yale.</P>
<P>Dr. Dickson, the lead author, said he ran into the laboratory when an
assistant called him on a Sunday night with the results. "This really makes you
think about how much of our behavior, perhaps especially sexual behaviors, has a
strong genetic component," he said.</P>
<P>All the researchers cautioned that any of these wired behaviors set by master
genes will probably be modified by experience. Though male fruit flies are
programmed to pursue females, Dr. Dickson said, those that are frequently
rejected over time become less aggressive in their mating behavior. </P>
<P>When a normal male fruit fly is introduced to a virgin female, they almost
immediately begin foreplay and then copulate for 20 minutes. In fact, Dr.
Dickson and his co-author, Dr. Ebru Demir of the Institute of Molecular
Biotechnology, specifically chose to look for the genetic basis of fly sexual
behavior precisely because it seemed so strong and instinctive and, therefore,
predictable. </P>
<P>Scientists have known for several years that the master sexual gene, known as
fru, was central to mating, coordinating a network of neurons that were involved
in the male fly's courtship ritual. Last year, Dr. Bruce Baker of Stanford
University discovered that the mating circuit controlled by the gene involved 60
nerve cells and that if any of these were damaged or destroyed by the
scientists, the animal could not mate properly. Both male and female flies have
the same genetic material as well as the neural circuitry required for the
mating ritual, but different parts of the genes are turned on in the two sexes.
But no one dreamed that simply activating the normally dormant male portion of
the gene in a female fly could cause a genetic female to display the whole
elaborate panoply of male fruit fly foreplay.</P></DIV></DIV></BODY></HTML>