In a major shake-up of scientists' understanding of what determines the fate of cells, researchers at the Walter and Eliza Hall Institute have shown that cells have some control over their own destiny. The researchers, from the institute's Immunology division, drew their conclusion after studying B cells, immune system cells that can make antibodies. B cells can have multiple fates. Some of the more common fates are to die, divide, become an antibody-secreting cell or change what antibody they make. This all happens while the cells are proliferating in the lymph nodes. The commonly-held view is that a cell's fate is determined by external cues such as the presence of particular hormones or cell signaling molecules. However the Walter and Eliza Hall Institute's head of immunology, Professor Phil Hodgkin, and colleagues Dr Mark Dowling, Dr Cameron Wellard and Ms Jie Zhou, predicted that cell fates are, to a large extent, determined by internal processes.
An experimental drug that once made the headlines as the "couch potato pill", for its capacity to mimic the effects of exercise in sedentary mice, may have another use, as a way to protect against heat stroke. In a new study about to be published in the journal Nature Medicine, scientists describe how the experimental therapy, called AICAR, protected animals with a genetic predisposition to heat stroke. They hope it means the drug holds promise for treating people who are susceptible to heat-induced sudden death. We have seen headlines about people unexpectedly dying from heat stroke. A physically fit young athlete, seemingly no different from his colleagues, suddenly dies on the football field during a sweltering hot day in August, or the victim could be an elderly woman gardening in the middle of a hot July day.
Providing clues to deafness, researchers at Washington University School of Medicine in St. Louis have identified a gene that is required for proper development of the mouse inner ear. In humans, this gene, known as FGF20, is located in a portion of the genome that has been associated with inherited deafness in otherwise healthy families. "When we inactivated FGF20 in mice, we saw they were alive and healthy, " says senior author David M. Ornitz, MD, PhD, the Alumni Endowed Professor of Developmental Biology. "But then we figured out that they had absolutely no ability to hear." The results, published online Jan. 3 in PLoS Biology, show that disabling the gene causes a loss of outer hair cells, a special type of sensory cell in the inner ear responsible for amplifying sound. While about two-thirds of the outer hair cells were missing in mice without FGF20, the number of inner hair cells, the cells responsible for transmitting the amplified signals to the brain, appeared normal.
Researchers at the University of California, San Francisco and the Stowers Institute for Medical Research have discovered that planarians, tiny flatworms fabled for their regenerative powers, completely lack centrosomes, cellular structures that organize the network of microtubules that pulls chromosomes apart during cell division. The flatworms' unique and unexpected characteristic, detailed in the Jan. 5, 2012 issue of Science Express, not only allowed lead author Juliette Azimzadeh, Ph.D., to identify a large set of conserved proteins required for centriole assembly in human cells but it also indicates that centrosomes, long thought to be required primarily for cellular functions such as cell division, have been retained in other animal species to coordinate specific developmental rather than cellular processes.
A new study led by Massachusetts Institute of Technology (MIT) biologist Leonard Guarente, who over 15 years ago discovered the lifespan-extending effects of a set of proteins called sirtuins, and who since has shown they play a key biological role in promoting survival in response to very-low-calorie diets, has found that they also play a key role in the psychological response to calorie restriction. Working with mice, he and his colleagues showed that when brain levels of sirtuins are high, which is what happens when diet is restricted, the animals become much more anxious. The researchers hope their findings will help inform the development of drugs that target sirtuins, such as some currently being explored for the treatment of Alzheimer's and other neurological diseases. They write about their findings in the 8 December online issue of the journal Cell.