Key role as disease partner likely for dolphins

AAAS annual conference:DOLPHINS ARE likely to become important partners in the study and treatment of human diseases. Although significantly different to us, there are more similarities than expected – not least their exceptionally large brains.

These place particular demands on dolphins in terms of food and metabolism, a session of the American Association for the Advancement of Science (AAAS) annual meeting heard. One surprising result is that they may be a valuable model for human diabetes. We have no natural animal model for type II diabetes.

Dolphins appear to turn on and off a diabetes-like state as needed. This “switch” mechanism is likely driven by dolphins’ high-protein and low-carbohydrate fish diet. It is similar to changes seen in people with diabetes, offering an opportunity to do comparative studies, the session heard.

Another important human disease where the dolphin may be of help is cervical cancer triggered by the papillomavirus. “We discovered that dolphins get multiple infections of [various] pillomaviruses which are known to be linked with cervical cancer in women,” explained Prof Hendrik Nollens, a marine biologist at University of Florida.

“Dolphins are the only species besides humans that we know of that can harbour coinfections or infections of multiple papillomavirus types,” he said. Dolphins do not go on to develop cancer, and researchers are trying to learn why, Prof Nollens said.

These animals may also inform us about the impact of long-term exposures to pollutants. “Dolphins and humans are both mammals, and their diet includes much of the same seafood that we consume. Unlike us, however, they are exposed to potential ocean health threats such as toxic algae or poor water quality 24 hours a day,” said Dr Carolyn Sotka of the US National Oceanic and Atmospheric Organisation.

One consequence of this was the discovery of dolphins with high levels of polychlorinated biphenyls (PCBs). These chemicals build up in fatty tissue and can suppress the immune system and cause other harmful effects also seen in humans.