A small calf stands in a cattle stall on a farm outside Sioux
Center, Iowa, and peers outward with the doe-eyed charm that would
make it a natural poster pet for a local 4-H Club.
This calf, however, is unique. Native to the island of Java, the
week-old banteng calf is the longest-surviving clone of an
endangered animal. It represents the most successful attempt yet for
efforts to see whether cloning - a deeply controversial technology
for human-related research - can become a feasible tool to help save
Yet it also is a field of research where success is still
measured in days. The calf is one of two cloned banteng born last
week. The second, born at twice a banteng's typical birth weight of
40 pounds, was euthanized on Tuesday. Two years ago, researchers
cloned an endangered wild ox they named Noah, only to lose the calf
two days later to an unrelated illness.
Still, the fact that the two banteng arrived at all is a
landmark, researchers say.
"I was absolutely astounded when I saw the picture of the living
animal that came from one of these cells that came out of our
freezers," says Oliver Ryder, a geneticist at the San Diego Zoo's
Center for Reproduction of Endangered Species, which supplied the
genetic material to clone the calves.
For years, Dr. Ryder and a group of colleagues have argued that
researchers should begin building DNA "banks" where tissue and other
sources of genetic and reproductive material from endangered species
would be archived. San Diego Zoo began to store samples in its
"frozen zoo" in 1976 and now has collections of viable cells from
more than 3,200 mammals representing 355 species and subspecies -
all preserved at liquid-nitrogen temperatures.
The zoo shipped banteng cells preserved since 1980 to Advanced
Cell Technology, a Worcester, Mass., biotech firm. There,
technicians took DNA from the samples and transferred it to domestic
cow eggs that had been stripped of their DNA. ACT fertilized the
modified eggs and shipped the resulting embryos to another biotech
company in Sioux Center, Iowa, where they were implanted in 30 cows.
Sixteen cows became pregnant; two came to term.
The procedure's inefficiency and the loss of the second banteng
calf clearly indicate that conservation cloning is not ready for
prime time, researchers acknowledge, noting that the banteng
experiment was designed to help assess the technique's feasibility.
Others acknowledge that such cloning experiments may be of
scientific value. …