Monday, 30 August 2010

DNA Extracted from Dolphin ‘Blow’

Georgetown scientists are among the first researchers to extract DNA from a dolphin’s exhalations or “blow,” reducing the need for invasive biopsies commonly used to study these and other marine mammals.

Janet Mann, a professor of biology and psychology, and graduate students Ewa Krzyszczyk (G‘13) and Eric Patterson (G’12) worked with researchers at the National Aquarium and the University of Queensland to find a way to avoid using “dart biopsies,” which involve shooting the animal and extracting DNA from tissue left on the dart.

Avoids Injury
“Dart biopsying is considered inappropriate for very young animals and the technique requires considerable skill to avoid injuries,” Mann says. “Thus identifying alternative genetic collection techniques for these animals remains a priority, especially for internationally protected species.”

Mann is a senior author on an article showing how “blow sampling” is as good a method of DNA extraction as blood sampling. The article was published in the Aug. 25 edition of the online scientific journal PLoS ONE.

Exhaling on Cue

At the National Aquarium in Baltimore, Md., both blow and blood samples were collected between March and May 2010 from six bottlenose dolphins. A test tube was held inverted over the dolphin’s blowhole as they were trained to exhale on cue and a control sample of seawater was taken to ensure that DNA results were from blow samples and not seawater contamination.

The scientists proved that both the blow and blood samples resulted in perfectly matched DNA for each dolphin. The National Science Foundation and Georgetown provided funding for the research.

DNA and Shark Bay
The authors are now applying their new method to a wild population of bottlenose dolphins in Western Australia’s Shark Bay, where they have studied the animals for more than two decades.

“Both biopsy and blow-sampling require close proximity of the boat, but blow-sampling can be achieved when dolphins voluntarily come close to the boat and involves no harmful contact,” Mann says.


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