May 01, 2002


 DNA banks: Could they help manage disease and conserve animals?

Posted April 15, 2002

The California condor, which is teetering on the edge of extinction, is fighting to make a comeback with the help, in part, of DNA banks. This is just one example of how DNA banks can help fight disease and save endangered species, said Oliver Ryder, PhD, a geneticist at the Zoological Society of San Diego.

By analyzing DNA samples, conservationists have identified kinships among the birds, which has helped them prevent inbreeding and the spread of genetic diseases. "There is a genetic disease in California condors, a kind of dystrophy, a disruption in the normal pattern of bone development, and birds [with this disease] don't survive," Dr. Ryder said. This disease could threaten the success of reintroduction and recruitment in the wild, but using genetic analysis, scientists have been able to breed birds without the disorder.

Using the condors as one example, Dr. Ryder argued for the development of a network of DNA banks to preserve the genetic material of animal species, at the recent American Association for the Advancement of Science meeting.

Dr. Ryder bolstered his argument with several other examples, including a project involving the black rhinoceros. In an effort to examine the genetic variation of this animal, researchers collected DNA samples from rhinoceroses in Zimbabwe when they were being experimentally dehorned roughly 10 years ago, a policy aimed at reducing the incentive to hunt the animals for their horns.

Using genetic analysis, researchers identified two kinds of black rhinoceroses, one found in east Africa and one in Zimbabwe. This discovery has affected conservation planning, but the study was also important because poachers, most likely, have killed all the Zimbabwe rhinoceroses from which DNA samples were extracted.

"We have a portion of the gene pool that is rapidly disappearing," Dr. Ryder said. "At that time, there was thought to be 2,000 black rhinos in Zimbabwe, and now it is more on the order of 200."

DNA banks would help scientists understand, treat, and diagnose diseases that affect endangered species, the San Diego geneticist argued. He is one of a group of scientists who are proposing a Web-based register of DNA banks to collect information already available and encourage other projects.

The plan, however, is somewhat controversial. In an interview with ABC, James Patton, PhD, a professor of integrative biology at the University of California at Berkeley and director of the university's Museum of Vertebrate Zoology, voiced concerns over security of the bank's information, worrying that location data for animal tissue samples could be used by individuals who want to raid areas for commercial sales. Others think that saving habitat, crucial for animal survival, should be the first priority.

Currently, Dr. Ryder is seeking suggestions about the design of the Web site from scientific and conservation communities. "The genome sciences are another microscope in the history of biology—they are going to cause us to see the world through a new lens," said Dr. Ryder, waxing philosophic. "The future will find uses for the information obtainable from DNA banks that we cannot presently imagine."