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Scientists at the San Diego Zoo and Scripps Research Institute may be on the verge of a breakthrough that could prove to be the lifeline needed to save many endangered species. Studies will begin with the critically endangered northern white rhinoceros (Ceratotherium simum cottoni) and endangered drill (Mandrillus leucophaeus)(*pictured), a primate closely related to the baboon and mandrill.

Jeanne Loring, a PhD and professor of developmental neurobiology, along her colleagues at Scripps have created stem cells for both the drill and northern white rhino using previously frozen skin samples taken from the animals. By using modern cellular biology techniques, scientists were able to get skin cells to revert to an earlier stage of development. From there, it’s hoped they can be manipulated into eggs and sperm , which in turn can be used for in vitro fertilization of live eggs or the creation of an embryo to be planted in a live host animal.

The process could also help foster genetic diversity in species with severely limited populations. For example, there are only seven known northern white rhinos living, all in captivity, and two of them are in San Diego.

The groundwork for the project was laid as far back as 1972, when workers at the San Diego Zoo began collecting and freezing skin samples from endangered species with the hope of someday using the tissue to prevent the extinction of threatened animals. Today, the “Frozen Zoo” holds skin cells and other tissue from over 800 different species.

Oliver Ryder, PhD and director of genetics at the San Diego Zoo Institute for Conservation Research, originally approached Loring about five years ago. At the time, scientists had not yet developed the technique known as pluripotency, which causes adult cells to revert to their stem cell state, from which they can be manipulated in their development.

Ryder admits that his research isn’t ideal as a primary method of protecting endangered species. “The best way to manage extinctions is to preserve species and their habitats, but that's not working all the time,” he says. Commenting on the rhinos, he continues that “[s]tem cell technology provides some level of hope that they won't have to become extinct even though they've been completely eliminated from their habitats. I think that if humankind wants to save this species, we're going to have to develop new methodologies.”

The rhinos were chosen as one of the first two project animals for the stem cell research due to the highly threatened nature of their population. The drill, while also endangered but of lesser immediate concern, was selected due to its genetic similarity to humans and the tendency for the primates in captivity to develop diabetes due to a lack of biodiversity.

The Scripps and Zoo team are currently seeking more funding to continue their stem cell work, but figuring out where to go for grant money is challenging. "It's in between fields," explains Loring. "It's not classical conservation and it's not ordinary biological research."

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Joaquin_de_la_Mesa Sept. 6, 2011 @ 10:54 a.m.

I was under the impression that once any species got down to less the 50 or so representatives, that it was as good as gone -- because the gene pool is too small at that point.

I think I heard that at the Wild Animal Park. If that's the case, how can they save the northern white rhino?

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