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Archive - Mar 3, 2011

DNA Testing Links Habitat Quality to Diet in Bats

New DNA testing technology has allowed scientists to compare the diets of bats consuming food from agricultural environments versus those of bats consuming food from conservation environments. The results indicate that bats feeding in agricultural environments have more restricted diets than do bats feeding in conservation environments. Working at three sites in Southern Ontario (Canada) the research team of students and scientists monitored the diet of little brown bats (Myotis lucifugus) from colonies living on agricultural land and at a conservation site. Guano (bat feces) was continually collected under each roost from May to August. Back in the lab at the Biodiversity Institute of Ontario in Canada, the team extracted insect DNA from the material and sequenced a "DNA barcode" which is a small region of DNA that can be used to identify animal species. The team then matched these unknown insect sequences in bat guano to a library of known sequences to identify which insect prey the bats were eating. "This technology is very new," said lead author Dr. Elizabeth Clare of the University of Bristol's School of Biological Sciences. "It gives us an entirely new insight into the bats' behavior. Instead of just finding they ate a moth or a mayfly, we now know exactly what species of insect it was, providing us with important information on their habitat." Using this technique, the team found that the bats rely heavily on insects from aquatic environments. They were also able to identify the exact species of insect prey, which revealed that different colonies exploit different source water, sometimes rivers and streams, sometimes ponds, depending on the local landscape. "Some of the insects they eat come from very specific habitats and have specific pollution tolerances.

Scientists Identify Genetic Susceptibility Factor for Bipolar Disorder

A genome-wide association study has revealed that genetic variation in the neurocan (NCAN) gene is significantly associated with bipolar disorder in thousands of patients. Importantly, in a follow-up study, these findings were replicated in tens of thousands of individual samples of bipolar disorder. The researchers went on to show that the mouse version of this gene, which is written Ncan and is thought to be involved in neuronal adhesion and migration, is strongly expressed in brain areas associated with cognition and the regulation of emotions. Although mice without functional Ncan did not exhibit obvious defects in brain structure or basic cell communication, there did appear to be some perturbation in mechanisms associated with learning and memory, mechanisms that have been associated with the cognitive deficits observed in bipolar disorder. However, the authors caution that Ncan-deficient mice need to be re-examined for more subtle brain changes and behavioral abnormalities. "Our results provide strong evidence that genetic variation in the gene NCAN is a common risk factor for bipolar disorder," concluded Dr. Sven Cichon of the University of Bonn, one of the leaders of the study. "Further work is needed now to learn more about the biological processes that NCAN is involved in and how NCAN variants disturb neuronal processes in patients with bipolar disorder." The NCAN work was published online on February 24, 2011, in the American Journal of Human Genetics. [Press release] [AJHG abstract]