Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Two genes -- Dax 1 and Sry -- required for testis formation

09.04.2003


The sex of newborns is dictated by the X and Y chromosomes – girls are XX whereas boys are XY. However, new research from Northwestern University has shown that normal testis formation depends on two genes -- the so-called male-determining SRY gene, found on the Y chromosome 10 years ago, and a gene called Dax1 on the X (female) chromosome.
Based on the findings of the Northwestern study, published in the May online Nature Genetics, it now appears that Dax1 is required at several points in embryonic testis development (http://dx.doi.org/10.108/Ng1141).

Until this study, Sry was the only known sex-determining gene. Dax1 had been widely accepted as an “anti-testis” or ovary-determining gene because patients with a duplication or “double dose” of Dax1 had features of XY sex reversal, a condition in which individuals have the chromosomes of males but the physical attributes of females.


Despite these findings, laboratory studies showed that deletion of the Dax1 gene in mice did not prevent ovarian development but instead revealed an important role in testis development.

Because most XY females do not have Sry mutations, Joshua J. Meeks, Jeffrey Weiss, and J. Larry Jameson, M.D., of the Feinberg School of Medicine at Northwestern University, hypothesized that other genes are necessary for testis determination.

Meeks, who is first author on the article, is an M.D./Ph.D. student at the Feinberg School. Weiss is research associate professor of medicine, and Jameson is Irving S. Cutter Professor and chair of medicine.

Their article described studies in XY sex-reversed mice lacking the Dax1 gene. Embryonic gonads were examined during the period when the bipotential gonad becomes a testis or an ovary.

Meeks and colleagues showed that the gonads of all of the Dax1-deleted XY sex-reversed mice had no testis cords -- a central feature of sex determination in males -- but had ovaries and external female genitalia and were anovulatory (sterile). Expression of the Sry gene was similar in Dax1-deleted mice and in those in which Dax1 was normal, indicating that sex reversal is not caused by reduced Sry levels in Dax1-deleted mice.

Further, Meeks said, “Sex reversal in the absence of Dax1 occurs subsequent to normal Sry expression, suggesting that Sry and Dax1 are both required for normal testis determination.” Meeks and colleagues at the Feinberg School have been studying the genetic mutations that cause sex reversal in an effort to reveal much-needed information about how these genes regulate gonad development and to better understand the causes of gonadal dysgenesis and infertility in humans.


This study was supported by a grant from the National Institutes of Health.


Elizabeth Crown | EurekAlert!
Further information:
http://www.nwu.edu/
http://dx.doi.org/10.108/Ng1141

More articles from Life Sciences:

nachricht Water world
20.11.2017 | Washington University in St. Louis

nachricht Carefully crafted light pulses control neuron activity
20.11.2017 | University of Illinois at Urbana-Champaign

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>