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Archive - Mar 8, 2013

Hypocretin Peptide May Play Role in Human Happiness

The neurochemical changes underlying human emotions and social behavior are largely unknown. Now though, for the first time in humans, scientists at UCLA have measured the release of a specific peptide, a neurotransmitter called hypocretin, which greatly increased when subjects were happy, but decreased when they were sad. The finding suggests that boosting hypocretin could elevate both mood and alertness in humans, thus laying the foundation for possible future treatments of psychiatric disorders like depression by targeting measureable abnormalities in brain chemistry. In addition, the study measured for the first time the release of another peptide, this one called melanin concentrating hormone, or MCH. Researchers found that its release was minimal during waking periods, but greatly increased during sleep, suggesting a key role for this peptide in making humans sleepy. The study was published online on March 5, 2013 in Nature Communications. "The current findings explain the sleepiness of narcolepsy, as well as the depression that frequently accompanies this disorder," said senior author Dr. Jerome Siegel, a professor of psychiatry and director of the Center for Sleep Research at UCLA's Semel Institute for Neuroscience and Human Behavior. "The findings also suggest that hypocretin deficiency may underlie depression from other causes." In 2000, Dr. Siegel's team published findings showing that people suffering from narcolepsy, a neurological disorder characterized by uncontrollable periods of deep sleep, had 95 percent fewer hypocretin nerve cells in their brains than those without the illness. That study was the first to show a possible biological cause of the disorder. Because depression is strongly associated with narcolepsy, Dr.

Signaling Molecule May Help Stem Cells Make Bone Despite Age, Disease

A signaling molecule that helps stem cells survive in the naturally low-oxygen environment inside the bone marrow may hold clues to helping the cells survive when the going gets tougher with age and disease, researchers report. They hope their findings, reported online on March 5, 2013 in the open-access journal PLOS ONE, will result in better therapies to prevent bone loss in aging and enhance success of stem cell transplants for a wide variety of conditions from heart disease to cerebral palsy and cancer. The scientists found that inside the usual, oxygen-poor niche of mesenchymal stem cells, stromal cell-derived factor-1, or SDF-1, turns on a survival pathway called autophagy that helps the cells stay in place and focused on making bone, said Dr. William D. Hill, stem cell researcher at the Medical College of Georgia (MCG) at Georgia Regents University (GRU) and the study's corresponding author. Unfortunately, with age or disease, SDF-1 appears to change its tune, instead reducing stem cells' ability to survive and stay in the bone marrow, said Samuel Herberg, GRU graduate student and the study's first author. Additionally, cells that do stay put may be less likely to make bone and more likely to turn into fat cells in the marrow. The researchers believe it's the changes in the normal environment that come with age or illness, including diminished nutrition, that prompt SDF-1's shifting role. "You put new cells in there and, all of the sudden, you put them in a neighborhood where they are being attacked," Dr. Hill said.

Algae Tolerant of Extreme Environments Offer Wal-Mart of Genomic Material

Most organisms would die in the volcanic sulfur pools of Yellowstone and Mount Etna. Robust simple algae call these extreme environments home, and their secrets to survival could advance human medicine and bioremediation. Dr. Mike Garavito, Michigan State University (MSU) professor of biochemistry and molecular biology was part of a research team that revealed how primitive red algae use horizontal gene transfer, in essence stealing useful genes from other organisms to evolve and thrive in harsh environments. Their study, published in the March 8, 2013 issue of Science, shows that the algae’s ability to adapt to a hot and extremely acidic environment ¬lies in part in their membrane proteins. “The algae’s membrane proteins are biologically quite interesting because they’re receptors and transporters, the same classes of proteins that play key roles in energy metabolism and human immune response,” said Dr. Garavito. “This has applications in human medicine because virtually all of the important pathways that contribute to disease treatment involve membrane proteins.” What makes the algae’s membrane proteins attractive as a model for humans is their robustness. Other traditional candidates, such as yeast, insect cell cultures, and slime mold, are fragile. The hardy algae give researchers extra time to manipulate and examine their membrane proteins. Dr. Garavito was part of a team of researchers led by Dr. Andreas Weber, former MSU researcher now at Heinrich-Heine-Universitat Dusseldorf (Germany). While at MSU, Dr. Weber led a team in first sequencing the algae, one of the first major genome sequencing projects at MSU. “Dr. Weber knew that this would be a good organism from which to harvest a wide variety of genes that could be potential models for those involved in human health and disease,” said Dr.

Sequencing Study of Dust Mites Demonstrates Reversible Evolution

In evolutionary biology, there is a deeply rooted supposition that you can't go home again: Once an organism has evolved specialized traits, it can't return to the lifestyle of its ancestors. There's even a name for this pervasive idea. Dollo's law states that evolution is unidirectional and irreversible. But this "law" is not universally accepted and is the topic of heated debate among biologists. Now a research team led by two University of Michigan (U-M) biologists has used a large-scale genetic study of the lowly house dust mite to uncover an example of reversible evolution that appears to violate Dollo's law. The study shows that tiny free-living house dust mites, which thrive in the mattresses, sofas, and carpets of even the cleanest homes, evolved from parasites, which in turn evolved from free-living organisms millions of years ago. "All our analyses conclusively demonstrated that house dust mites have abandoned a parasitic lifestyle, secondarily becoming free-living, and then speciated in several habitats, including human habitations," according to Dr. Pavel Klimov and Dr. Barry O’Connor of the U-M Department of Ecology and Evolutionary Biology. Their paper is scheduled to be published online on March 8, 2013 in the journal Systematic Biology. Mites are arachnids related to spiders (both have eight legs) and are among the most diverse animals on Earth. House dust mites, members of the family Pyroglyphidae, are the most common cause of allergic symptoms in humans, affecting up to 1.2 billion people worldwide. Despite their huge impact on human health, the evolutionary relationships between these speck-sized creatures are poorly understood. According to Drs.