Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geneticists identify ’master switch’ that causes female flies to behave like males

16.06.2005



Turning on a single male-specific gene produces a female fruit fly that displays male courtship behaviors: chasing other females, tapping their abdomens and performing wing-beating love serenades. The results, published in the June 15 online edition of the journal Nature, show that a single gene can determine how females and males detect and respond differently to sexual cues.

’’In these experiments we see all the steps of the male courtship ritual you could physically expect a female fly to do,’’ says Bruce S. Baker, the Dr. Morris Herzstein Professor in Biology at Stanford and co-author of the study. ’’It’s a male’s behavioral circuitry in a female body.’’

Baker and Stanford graduate student Devanand S. Manoli and their collaborators at Brandeis and Oregon State universities focused on a gene known as fruitless-one of approximately 13,000 genes in the DNA of the common fruit fly, Drosophila melanogaster. The three laboratories had previously discovered that fruitless is the master gene controlling the male fruit fly’s elaborate six-step courtship ritual. Last year they showed that disabling the fruitless gene in a tiny group of cells in the brain of a male fruit fly was enough to prevent successful mating, by turning him into a bumbling, ineffective suitor.



In the new study, researchers asked whether the fruitless gene would be enough to elicit male courtship behavior in female flies. They activated the gene in neural cells in the female fly’s brain and sensory organs. When paired with a virgin female fruit fly, the masculinized females showed male courtship behavior: chasing the female fly and then tapping her on the abdomen. When a masculinized female was placed with a male, she responded to his advances with masculine rejection behavior-wing flicking and kicking-rather than the upturned posterior that is the normal female rejection response.

In a group setting, the masculinized female demonstrated even more aspects of male courtship behavior. She vibrated her wings in a mating song and occasionally extended her proboscis. Both are male-specific courtship behaviors that lead up to sexual intercourse.

’’This study genuinely and dramatically enhances our understanding of what the fruitless gene is about,’’ says co-author Jeffrey C. Hall, a biologist at Brandeis University in Waltham, Mass. ’’We created a powerful and novel way to manipulate an interesting gene-a gene that governs lifestyle and the whole courtship sequence.’’

Similar findings by researchers at the Austrian Academy of Sciences in Vienna were published June 2 in the journal Cell. The results had been predicted by Baker and colleagues in past experiments. ’’It’s been very gratifying to have this prediction of our previous studies confirmed,’’ Baker says, adding that the Nature study revealed other findings that were unexpected.

For example, the researchers found that when they took male flies and disabled the roughly 2 percent of brain cells that express the fruitless gene, the males had no interest in females but otherwise behaved normally-walking, flying and grooming as usual.

’’That’s surprising, that you could take a chunk of the brain, shut it down and get so little of an effect,’’ says Baker. This behavior implies that these brain cells don’t affect the body’s motor functions but are dedicated exclusively to sex.

Male and female perception

From the initial recognition of a mate by sight and smell to the final act of mating, courtship is mediated by a series of sensory cues passed between the male and female. And an animal’s ability to detect those cues influences its behavior. In flies, as in most animals, including humans, the sensory organs of females and males look identical-but they may not be detecting the same information.

’’It had been assumed that males and females sensed the world around them the same,’’ Baker says. The new findings, however, show that male fruitless is expressed not only in the brain but also in the sensory organs.

’’What that means is that males and females may well perceive the world differently, at least with things that are relevant to sex,’’ he adds. ’’Sense organs that look the same in two sexes may be fundamentally different at a molecular level.’’

In the Nature study, researchers pinpointed two instances in which the fruitless gene allowed male flies to detect smells that influenced their sexual behavior. Normally, while an inexperienced male often courts other males, he soon learns to refine his mating strategy. Such habituation was known to involve odors. The scientists now report that when they turn off the fruitless gene in the male fly’s ’’nose,’’ he persistently courts other males.

Also, it was known that if a male fruit fly was placed with a recently mated female she would reject his advances, and this conditioned him to temporarily lose interest in sex. The new findings show that if the fruitless gene is turned off only in the part of the male’s brain devoted to smell, he continues to chase females despite repeated rejections.

Sex in a single gene

Baker says that the work he and his colleagues have done over the past decade has made the fruitless system’s regulation better understood than that of any other behavioral network. Taken as a whole, the new findings provide further evidence that inborn sexual behaviors are hard-wired in animals’ genes.

’’When you come to behaviors that are innate, and therefore somehow built into the organism, and are fundamentally important, why wouldn’t evolution build that circuitry the same way it builds other parts of organisms, like legs, eyes and wings?’’ he says. Other behaviors-such as nesting, hibernation and nurturing-may be under the same type of genetic control, he concludes.

Although the fruitless gene has not yet been found in humans, a corollary may exist. At the cellular or genetic level, fruit flies are similar to other animals, including humans.

’’It wouldn’t surprise me to learn that human sexual behaviors also have, underneath them, a basic circuitry in the nervous system that mediates attraction and mating,’’ Baker notes, adding that recent research suggests specific genes build the circuits for instinctive behaviors, ranging from sex to aggression, in mammals. But human behavior, he cautions, is less fixed than that of fruit flies.

Other co-authors of the Nature study are Adriana Villella at Brandeis, and Barbara J. Taylor and Margit Foss at Oregon State University. Research was funded by a grant from the National Institute of Neurological Disorders and Stroke.

Dawn Levy | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Life Sciences:

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

nachricht When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

NASA examines Peru's deadly rainfall

24.03.2017 | Earth Sciences

What does congenital Zika syndrome look like?

24.03.2017 | Health and Medicine

Steep rise of the Bernese Alps

24.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>