China

January 24, 2018

Two Twin Long-Tailed Macaque Monkeys Are the First Primates Cloned Using the Dolly Method (arstechnica.com)

An anonymous reader quotes a report from Ars Technica: The twin long-tailed macaque monkeys are the first primates cloned using the same method that created the world’s most famous sheep in 1996 — a method called somatic cell nuclear transfer, or SCNT. The twins’ genetic blueprints were swiped from fetal cells of another monkey. Researchers then popped the DNA into egg cells that they had also cleared of their DNA-containing nuclei. With a dash of compounds that spur embryo development, the reprogrammed cells developed into healthy baby monkeys in surrogate mother monkeys. The two were born about seven weeks ago in China and are developing normally so far, researchers reported Wednesday in the journal Cell. Though the overall SCNT method is the same as what was used for Dolly, researchers struggled for years to tweak it to work in primates. The procedure is delicate and required a lot of optimization — not to mention DNA-swaps.

The researchers behind the cute clones, led by Zhen Liu of the Chinese Academy of Sciences, first tried using DNA from adult monkey cells. They created 192 embryos this way, implanting 181 of them into 42 surrogates, leading to 22 pregnant monkeys. But this resulted in the live birth of only two monkeys, both of which died within hours. Next, the researchers tried using DNA from fetal tissue. They created 109 embryos, implanted 79 of them into 21 surrogates, leading to pregnancy in six of them. Two female monkeys, Zhong Zhong and Hua Hua, resulted. The researchers attribute their success to new cell-imaging methods, tweaking the right mix of reprogramming compounds, and lots of practice.

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