生物技术与动物保护

[编者的话]

致力于动物保护的学者们一向把生物技术视为自然界的敌人，然而今天，生物技术却可以为动物保护提供有力的工具。Micorarry技术可以被用来诊断濒危动物的疾病起因分析，从而为拯救那些稀有动物作出贡献。

by Vicki Brower

SAN DIEGO, California - The protesters outside the BIO 2001 meeting in San Diego may see biotechnology as the enemy of nature, but speakers inside today showcased its use to conserve endangered animals including the giant panda, the Sumah orangutan, and the aplomado falcons. Like so many others, scientists affiliated with zoos are employing DNA microarrays and PCR, among other technologies, in their quest to hunt down the causes of illness in endangered animals and develop treatments for them. Meanwhile, they are able to explore the genetic differences and similarities between non-human primates and humans.

Research pathologist Mark Schrenzel at the San Diego Zoo's Center for Reproduction of Endangered Species last year established North America's first molecular pathology lab in the zoo world. To date, he has tracked down a previously unknown adenovirus afflicting aplomado falcons, which had finally begun returning to Southern California from Mexico after 30 years' work by conservationists. Last year, they suffered an acute outbreak of illness in which 57 baby falcons died.

"Using microscopic analysis of tissue, we found liver necrosis which pointed to a viral disease," he said. His team also discovered the virus in the liver and gallbladder, conducted CD3 immunostaining, and found that T cells were also infected. They isolated the virus, sequenced it and saw homology to known avian and human adenoviruses. Then they found that it affected the brain and CNS as well, and concluded that it could have been dormant until the birds were stressed. Schrenzel and colleagues developed a PCR test for viral shedding, and also identified epitopes they will use to develop a vaccine for the disease.

"We are also studying albinism in giant pandas," said Schrenzel, "an autosomal recessive trait that results in susceptibility to visual and neural problems." Knowing that coat color in animals is connected to the tyrosinase gene, Schrenzel cloned the first exon of the gene, and hopes to develop a PCR test for carriers, which would enable zookeepers to breed the albino trait away.

Schrenzel has also tracked down a chronic infectious disease in the douc langur, a leaf-eating monkey indigenous to Southeast Asia. The disease afflicts its gastrointestinal tract and weakens the langurs with chronic diarrhea and dehydration. The team has isolated and characterized a novel Helicobacter which co-infects the mammals with Campylobacter, and has been able to treat them and eliminate the illness.

Robert Feldman of Molecular Dynamics Inc. described using his company's MegaBace high-throughput screening instrument to study the mitochondrial genomes of endangered species with the San Diego Zoo. In the collaborative Mammalian Mitochondrial Genetic Ecology and Evolution Project, the Zoo is studying the phylogeny of mammals for use in evolutionary, breeding and conservation studies.

"The mitochondrial genome is an ideal marker for conservation studies, as it reveals a simple transmission pattern," Feldman said.

To date, the project has sequenced the mitochondrial genomes of 146 mammalian samples, including 900 primate samples, said Oliver Ryder, the Kleberg Genetics Chair at the Zoo's Center for Reproduction of Endangered Species.

"There is a need to broaden the sense of what are conservation techniques and technologies," he added. "Biotechnology possesses crucial tools for the future of many species, and should be considered part of the stewardship of conservation." It could also result in better understanding of biology and provide some direct benefits to humans, he predicted.