(Press-News.org) What do you get when you dissect 10 000 fruit-fly larvae? A team of researchers led by the EMBL-European Bioinformatics Institute (EMBL-EBI) in the UK and the Max Planck Institute of Immunobiology and Epigenetics (MPI) in Freiburg, Germany has discovered a way in which cells can adjust the activity of many different genes at once. Their findings, published in the journal Science, overturn commonly held views and reveal an important mechanism behind gender differences.
Asifa Akhtar's laboratory, previously at EMBL now at MPI, studies precisely how flies regulate an important set of genes. Females have two X chromosomes while males have only one, so the genes on the female X chromosomes somehow need to be kept from producing twice as many proteins as those on the male X chromosome. Male fruit flies get around this by making their X chromosome's genes work double time: an epigenetic enzyme doubles the output of thousands of different genes. But just how much that doubled output is can vary tremendously from one gene to the next.
"Imagine that you have thousands of half-filled glasses of all different sizes and shapes," explains Nick Luscombe, who led the work at EMBL-EBI. "Now imagine that you have to fill them all up to the top at the same time. This is an incredibly complex mechanism."
To see how genes are expressed, scientists try to pinpoint signals that show when a gene increases its output. In most studies of this kind, this output is increased by a factor of between 10 and 100 when a gene is being expressed. In this study, the signal involved is miniscule: an increase of only a factor of two.
Observing such a faint signal is a major challenge. But thanks to the painstaking fly-larvae dissection efforts of graduate student Thomas Conrad, combined with the detailed analytical efforts of Florence Cavalli and Juanma Vaquerizas, the team gathered enough material to measure this output and compare males and females directly.
The scientists found twice as many DNA-transcribing (reading) proteins – known as polymerases – attached to the male X chromosome as to the female version. This means that the difference between males and females is rooted in the beginning of the transcription process, when the polymerase first binds to the DNA. This goes against the commonly held view that the regulation mechanism is kicked off during transcription.
"A factor of two appears miniscule, so it is not easy to measure accurately," says Akhtar. "We were really doing a bulk analysis of several hundred genes, and that required a lot of careful bioinformatics analysis. Our group would run experiments, Nick's would analyse the data, and then we would decide on new experiments together to be sure that what we were seeing was real."
Discovering the machinery that doubles the expression of male X-chromosome genes could well have implications that go far beyond the humble fly. Speaking more technically, Luscombe says: "This is the first direct, clear mechanism that links a histone modification and the activity of a polymerase across thousands of genes".
Looking into future directions, Akhtar says: "We now need to look more deeply into what makes this kind of mass regulation possible, and how it fits in with other means cells may have to fine-tune their use of genetic information."
###
Source Article: Conrad, T., Cavalli, F.M.G., Vaquerizas, J.M., Luscombe, N.M., Akhtar, A. (2012) Drosophila dosage compensation involves enhanced Pol II recruitment to male X-linked promoters. Science (in press); published online 19 July. DOI: 10.1126/science.1221428
Read the article: http://www.sciencemag.org/lookup/doi/10.1126/science.1221428
END
The sun emitted a mid-level solar flare on July 19, 2012, beginning at 1:13 AM EDT and peaking at 1:58 AM. Solar flares are gigantic bursts of radiation that cannot pass through Earth's atmosphere to harm humans on the ground, however, when strong enough, they can disrupt the atmosphere and degrade GPS and communications signals.
The flare is classified as an M7.7 flare. This means it is weaker than the largest flares, which are classified as X-class. M-class flares can cause brief radio communications blackouts at the poles.
Increased numbers of flares are currently ...
PHILADELPHIA - Silymarin, an extract of milk thistle commonly used to treat chronic liver disease by millions of people around the World, does not offer significant improvements for patients, according to a new study conducted by a nationwide group of researchers including faculty at the Perelman School of Medicine at the University of Pennsylvania. Milk thistle fruit extracts have been widely used by patients in treating liver disease based on previous evidence showing that it has anti-inflammatory, anti-oxidant, and potentially anti-viral properties. However, the new ...
A new study from Lund University in Sweden has opened the way for new approaches to slowing the development of AIDS in HIV-1-infected patients. It is hoped that this could lead to better treatment methods and preventive measures to combat HIV and AIDS.
The findings have just been published in the distinguished scientific journal New England Journal of Medicine.
The most common type of the virus that causes AIDS – HIV-1 – is less aggressive when it infects a person already carrying the milder HIV-2. The study looked at how the disease developed in those who had been ...
MANHATTAN, KAN. -- A ratings system developed by a group of Kansas State University researchers could keep bridges safer and help prevent catastrophic collapses.
Hayder Rasheed, associate professor of civil engineering, and Yacoub Najjar, professor of civil engineering, are collaborating to better detect and measure damage in concrete bridges. Ahmed Al-Rahmani, doctoral student in civil engineering, United Arab Emirates, has also been involved in the project.
The researchers have created a bridge health index, which is a rating system that more accurately describes ...
Big data needs big power. The server farms that undergird the Internet run on a vast tide of electricity. Even companies that have invested in upgrades to minimize their eco-footprint use tremendous amounts: The New York Times estimates that Google, for example, uses enough electricity in its data centers to power about 200,000 homes.
Now, a team of Princeton University engineers has a solution that could radically cut that power use. Through a new software technique, researchers from the School of Engineering and Applied Science have opened the door for companies to ...
NEW YORK (July 19, 2012)— A dramatic photo of a male leopard dragging a massive gaur (or Indian bison) calf in Karnataka's Bandipur Tiger Reserve turned out to be the same animal photographed by a WCS camera trap nearly eight years ago.
The photo, taken by Indian photographer Vinay S. Kumar, was initially submitted to Conservation India, a not-for-profit portal to enable conservation action. Intrigued by the picture, CI's editors sent it to researchers at Wildlife Conservation Society's India Program who have been running a tiger-monitoring program for over two decades ...
Tired? Scientists have discovered another possible benefit of a night of restful and uninterrupted sleep. According to a new study led by researchers at the Johns Hopkins Bloomberg School of Public Health fragmented or interrupted sleep could predict future placement in a nursing home or assisted living facility. The study is featured in the July 2012 issue of the Journal of the American Geriatrics Society and outlines the association between objectively measured sleep and subsequent institutionalization among older women.
"Sleep disturbances are common in older people," ...
(Edmonton, AB) New research from the University of Alberta's School of Public Health has demonstrated that community-based resources in rural Uganda can successfully provide HIV treatments to patients, where economic and geographical barriers would typically prevent access to care.
Working with the Kabarole District Health Department and colleagues at Makerere University in Kampala, Uganda, the researchers implemented a new model by which volunteers were trained to provide basic care to HIV patients in Rwimi sub-county.
When comparing the viral loads of 185 patients ...
UT Dallas researchers recently demonstrated how nerve stimulation paired with specific experiences, such as movements or sounds, can reorganize the brain. This technology could lead to new treatments for stroke, tinnitus, autism and other disorders.
In a related paper, The University of Texas at Dallas neuroscientists showed that they could alter the speed at which the brain works in laboratory animals by pairing stimulation of the vagus nerve with fast or slow sounds.
A team led by Dr. Robert Rennaker and Dr. Michael Kilgard looked at whether repeatedly pairing vagus ...
Philadelphia, PA, July 19, 2012 – Outpatient heart failure (HF) clinics that provide patient education on ways to manage heart failure and risk factors, prescribe home-based exercises, and monitor therapy compliance have been shown to reduce morbidity, mortality, and health care costs. A new study published in the current issue of the Canadian Journal of Cardiology finds that despite guidelines that encourage physicians to recommend heart failure clinics, very few patients recently hospitalized with HF receive referrals or use one.
"Given the demonstrated benefits of ...
