Article: Sperm, Egg, Genes: New Research Reveals Unexpected Post-mating Gene Expression In Model Lab Insect
- From: "Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx>
- Date: Thu, 29 Jun 2006 01:12:51 -0400 (EDT)
Sperm, Egg, Genes: New Research Reveals Unexpected Post-mating Gene
Expression In Model Lab Insect
That cloud of tiny flies hovering around spoiled fruit isn't just a
nuisance. In fact, what science calls Drosophila melanogaster is more and
more the key to intricate genetic studies that shed light on numerous
biological processes, especially reproduction.
Now, evolutionary and developmental biologists at the University of Georgia
and the Hebrew University of Jerusalem have uncovered evidence that after
fruit flies mate, the presence of sperm and male proteins in the female's
reproductive tract sets off an amazing cascade of heretofore undescribed
gene activity. Understanding how this works will give scientists new
insights into reproduction, but it could also provide methods to safely
control the spread of insect pests by interfering with their reproduction.
"We have been able to define a large number of mating-responsive genes that
are activated in Drosophila," said Michael Bender, a developmental biologist
in the department of genetics at UGA. "There is a lot of potential in this
work for uncovering basic aspects of reproductive biology that will be
useful in pest-control approaches."
The research was just published in the online edition of the Proceedings of
the National Academy of Sciences. The work resulted from a collaboration
between Bender, Paul Mack, a postdoctoral fellow in the Bender lab at UGA,
Yael Heifetz of Hebrew University and Anat Kapelnikov, a graduate student in
the Heifetz lab. A number of undergraduates at UGA also worked on the
research.
Drosophila has been used as a model animal for nearly a century. It is easy
to manipulate in a lab, lives only a few weeks and begins mating soon after
hatching. Its entire genetic map or genome has also been sequenced, giving
researchers a powerful tool in understanding intricate biological processes
and the genes that direct them.
Bender's team, using both the established genomic background of Drosophila
and studies of mating insects, showed that the sperm and proteins
transferred from males to females during mating have "profound effects" on
female gene expression. Most surprising is that gene activity rapidly
escalates about six hours after mating--something previously unknown.
"We looked at the reproductive tracts of females at three, six and 24 hours
post-mating," said Mack. "Just getting enough material through dissection is
extremely difficult and time-consuming, but this kind of time-based
evaluation of post-mating gene expression in Drosophila had never been
done."
Perhaps surprisingly, very little is known about how gene expression in
female reproductive tissues changes in response to the presence of sperm and
male molecules. The study compared 3-day-old mated and unmated females and
discovered the presence in mated females of a startling 539 genes whose
activity changes after mating.
"One novel feature of this research was Paul's decision to look at what
happens over time," said Bender. "That's how we found out that the activity
hits a peak six hours after mating. This indicates quite a large genetic
response in the female tract to male-derived molecules and sperm."
Though considerable research has been done on male Drosophila over the
years, relatively little had focused on females. Just why the array of gene
expression peaks at 6 hours is not yet clear, but revealing this timing
could help in controlling insect pests. That is one reason the research was
funded by the Binational Agricultural Research and Development (BARD) Fund,
a joint program between the United States and Israel. Since 1979, BARD has
funded nearly 900 research projects in almost all 50 states. Support for the
research also came from The National Institutes of Health.
The Bender and Heifetz teams weren't operating in the dark, since earlier
studies had examined some post-mating gene expression in Drosophila, but
that earlier work did not examine expression over a set time period and
involved examining the whole bodies of mated insects, not just their
reproductive tracts.
The researchers' double approach using genomics and proteomics--the study of
proteins and the products they turn on--was especially productive because it
allowed them to identify genes they would not have found using a single
approach.
"The next step will be to choose a few of the most promising genes and to
explore their function in females," said Bender.
Once the gene functions are known, then scientists can begin to examine how
to manipulate them--both to study the biology involved and to find potential
targets for pest control.
Source: University of Georgia
http://www.sciencedaily.com/releases/2006/06/060627233740.htm
Posted by
Robert Karl Stonjek
.
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