Archive for February 2011
Mouse researchers conducting stress hormone experiments have stumbled onto a surprising new discovery — a potential treatment for hair loss.
Scientists at the University of California, Los Angeles, and the Veterans Administration were working with genetically altered mice that typically develop head-to-tail baldness as a result of overproducing a stress hormone.
Some fish in New York’s Hudson River have become resistant to several of the waterway’s more toxic pollutants. Instead of getting sick from dioxins and related compounds including some polychlorinated biphenyls, Atlantic tomcod harmlessly store these poisons in fat, a new study finds.
But what’s good for this bottom-dwelling species could be bad for those feeding on it, says Isaac Wirgin of the New York University School of Medicine’s Institute of Environmental Medicine in Tuxedo. Each bite of tomcod that a predator takes, he explains, will move a potent dose of toxic chemicals up the food chain — eventually into species that could end up on home dinner tables.
From 1947 to 1976, two General Electric manufacturing plants along the Hudson River produced PCBs for a range of uses, including as insulating fluids in electrical transformers. Over the years, PCB and dioxin levels in the livers of the Hudson’s tomcod rose to become “among the highest known in nature,” Wirgin and his colleagues note online Feb. 17 in Science. Because these fish don’t detoxify PCBs, Wirgin explains, it was a surprise that they could accumulate such hefty contamination without becoming poisoned. His team now reports that the tomcod’s protection traces to a single mutation in one gene. The gene is responsible for producing a protein needed to unleash the pollutants’ toxicity.
Gut microbes acquired early in life can impact brain development in mice and subsequent behavior, such as decreasing physical activity and increasing anxiety, according to a study published this week in the Proceedings of the National Academy of Sciences.
“This paper opens the door to new studies in at least two directions,” Yale University microbiologist Andrew Goodman, who was not involved in the research, told The Scientist in an email. “First, determining how differences between complete host-associated microbial communities lead to differences in behavior, and second, exploring the contributions of microbes during specific developmental periods in the host.”
Gut microbiota often colonize their hosts early in life, either during pregnancy or following birth, and play an integral role in the health of developing organisms. Previous research has shown that the bacteria affect the development of liver function, the protection epithelial cells afford underlying digestive tissue, gut regulation and the growth of new capillary blood vessels. But this is the first time gut flora have been linked to brain development and behavior.
Retinal implants can already restore sight to people who have lost it owing to degenerative eye diseases like macular degeneration or retinitis pigmentosa. Now new research suggests a way to make higher-quality, more biocompatible retinal implants by integrating living neural cells with a soft organic polymer semiconductor.
A retinal implant restores vision by sending a signal from a video camera attached to a pair of glasses to electrodes implanted on the back of a person’s retina. But the silicon or platinum components typically used to for the electrodes tend to produce images of limited quality, and can leave the retina scarred.
This tiny, near-microscopic water flea has more genes than you. In fact, this freshwater zooplankton is the first crustacean to have its genome sequenced, and its 31,000 genes crowns it the animal with the most genes so far. For those keeping count at home, the average human has about 20,000 to 25,000 genes.
The translucent water flea is a Daphnia pulex, and lives in ponds and lakes throughout North America, Europe and Australia. It can also reproduce without sex, is the most commonly found species of water flea and is a “model organism”, meaning it’s studied extensively and provides insight into other, rarer species.
The reason for this little critters’ super-high gene count comes down to its rapid rate of gene multiplication. “We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of humans,” project leader and CGB genomics director John Colbourne said in a press release.
Synthetic blood vessels that can be made in advance and stored until surgery could help patients undergoing heart surgery, hemodialysis—cleansing of the blood in cases of kidney failure—and other procedures. Laura Niklason, an anesthesiologist and biomedical engineer at Yale University, and her collaborators have grown blood vessels using human cells and tested them in baboons, showing that they provoke no immune rejection and avoid common complications of synthetic vessels, such as clotting, bursting, or contracting over time. Researchers hope these studies will show that the vessels are safe enough to win permission from the U.S. Food and Drug Administration to begin clinical trials.
The human retina — the part of the eye that converts incoming light into electrochemical signals — has about 100 million light-sensitive cells. So retinal images contain a huge amount of data. High-level visual-processing tasks — like object recognition, gauging size and distance, or calculating the trajectory of a moving object — couldn’t possibly preserve all that data: The brain just doesn’t have enough neurons. So vision scientists have long assumed that the brain must somehow summarize the content of retinal images, reducing their informational load before passing them on to higher-order processes.
At the Society of Photo-Optical Instrumentation Engineers’ Human Vision and Electronic Imaging conference on Jan. 27, Ruth Rosenholtz, a principal research scientist in the Department of Brain and Cognitive Sciences, presented a new mathematical model of how the brain does that summarizing. The model accurately predicts the visual system’s failure on certain types of image-processing tasks, a good indication that it captures some aspect of human cognition.