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Archive - Jan 17, 2014

Scientists ID Evolutionary Switch in Regulation of Low Oxygen Response in Fungi; Possible Huge Clinical Impact

All but a few eukaryotes die without oxygen, and they respond dynamically to changes in the level of oxygen available to them. University College Dublin (UCD) scientists used genetic analysis to pinpoint an evolutionary switch in regulating response to low oxygen levels in fungi. One example of an ancient oxygen-requiring biochemical pathway in eukaryotes is the biosynthesis of sterols, producing cholesterol in animals and ergosterol in fungi. The mechanism regulating the sterol pathway is widely conserved between animals and fungi and centers on a protein family of transcription activators named the sterol regulatory element binding proteins (SREBPs), which form part of a sterol-sensing complex. However, in one group of fungi; the Saccharomycotina, which includes the model yeast Saccharomyces cerevisiae and the major pathogen Candida albicans, control of the sterol pathway has been taken over by an unrelated regulatory protein, Upc2. New research published in PLOS Genetics by UCD researchers, in collaboration with colleagues from AgroParisTech, France, and the University of Kansas, USA, used comparative genomic analysis to investigate the timing of the evolutionary switch from one regulatory mechanism to another; from SREBPs to Upc2. Led by Professor Geraldine Butler, UCD Conway Institute and UCD School of Biomolecular & Biomedical Science, the group found that one yeast species, Yarrowia lipolytica (image), is unique in that it contains both SREBP and Upc2 genes. Y. lipolytica is used in the biotechnology industry to produce lipids and lies at the base of the Saccharomycotina group. Using a mixture of genetic and biochemical analysis, the group showed that Upc2 is the main regulator of the hypoxic response in Y.

How Male Black Widow Avoids Appearing As Prey When Approaching Potential Mate

A team of Simon Fraser University (Canada) (SFU) biologists has found that male black widow spiders shake their abdomens to produce carefully pitched vibrations that let females know they have “come a-courting” and are not potential prey. The team’s research has just been published online on January 17, 2014 in the open-access journal Frontiers in Zoology. SFU graduate students Samantha Vibert and Catherine Scott, working with SFU biology professor Dr. Gerhard Gries, recorded the vibrations made by male black widow spiders (Latrodectus hesperus), hobo spiders (Tegenaria agrestis), and prey insects. Ms. Scott explains: “The web functions as an extension of the spider's exquisitely tuned sensory system, allowing her to very quickly detect and respond to prey coming into contact with her silk. This presents prospective mates with a real challenge when they first arrive at a female's web: they need to signal their presence and desirability, without triggering the female's predatory response.” The researchers found that the courtship vibrations of both species differed from those of prey, but that the very low-amplitude vibratory signals produced when male black widows shake their abdomens were particularly distinctive. “These 'whispers' may help to avoid potential attacks from the females they are wooing," explains Ms. Scott. [Press release] [Frontiers in Zoology article]

Scientists Find Possible Cure for Deadly Flesh-Eating Streptococcus Infection

Collaboration between the National University of Singapore (NUS) and The Hebrew University of Jerusalem (HUJ) on inflammation research may lead to a potential treatment for deadly bacterial infections. Scientists from the NUS-HUJ-CREATE Inflammation Research Programme based in Singapore have found that asparaginase (ASNASE) – the enzyme that degrades the amino acid asparagine and serves as a common chemotherapeutic agent – arrests Group A Streptococcus (GAS) growth in human blood and blocks bacteria’s proliferation, thus initiating a new potential treatment against deadly Streptococcal infections. These findings were published in the January 16, 2014 issue of the prestigious journal Cell. The research program is funded by the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program. The NUS-HUJ-CREATE Inflammation Research Program was established in 2011, and is focused on advancing an understanding of cellular and molecular mechanisms of inflammation of diseases prevalent in Asia, a field that is currently under-studied. GAS is a strict human pathogen that causes a wide range of infections, from mild to deadly. It can colonize the host without causing any symptoms, or cause mild infections of skin and trough such as pharyngitis. On the invasive end of the spectrum, GAS can cause life-threatening infections such as bacteremia, necrotizing fasciitis (commonly known as flesh-eating disease), and streptococcal toxic shock syndrome. Annually, disseminated GAS infections cause approximately 160,000 deaths globally and severe injuries to those infected.

Vitamin D Relaxes Blood Vessels, Affects Blood Pressure

It’s not just your mood that the dark months of winter can influence. Low levels of sunlight also mean lower levels of vitamin D in the body. Vitamin D deficiency can trigger a range of diseases, but until recently little was known about the exact biological mechanisms behind this. A research team at the University of Veterinary Medicine, Vienna, Austria, has now decrypted one of these unknown molecular mechanisms. Vitamin D regulates the elasticity of blood vessels and thus also affects blood pressure amplitude. The results were published in the January 2014 issue of Molecular Endocrinology. UV-B radiation in sunlight is the most important factor for the production of vitamin D, and that is why many people suffer from low levels of vitamin D during the winter months. Although certain foods do contain vitamin D, it is not usually possible to get an adequate supply of the vitamin from food. Many clinical studies have indicated that low vitamin D levels are related to cardiovascular disease such as high blood pressure, but also other diseases such as diabetes mellitus, autoimmune diseases, and even cancer. However, the underlying molecular mechanisms were unclear. The two primary authors of the Molecular Endocrinology article, molecular biologist Dr. Olena Andrukhova and medical doctor Svetlana Slavic, of the Institute of Physiology, Pathophysiology, and Biophysics at the Vetmeduni Vienna, found that prolonged vitamin D deficiency can stiffen blood vessels. Examining the aorta, an elastic blood vessel that expands with each pulse of blood and then constricts again, the researchers showed that vitamin D deficiency makes the vessel less flexible. Dr. Andrukhova explains in detail: "Vitamin D enhances the production of the enzyme eNOS (endothelial nitric oxide synthase) in the inner layer of blood vessels, the endothelium.