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Japanese scientists create world’s first transgenic monkeys

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In a controversial achievement, Japanese scientists announced on Wednesday they had created the world’s first transgenic primates, breeding monkeys with a gene that made the animals’ skin glow a fluorescent green.

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The exploit opens up exciting prospects for medical researchers, they said.

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It could eventually lead to lab monkeys that replicate some of humanity’s most devastating diseases, providing a new model for exploring how these disorders are caused and how they may be cured.

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“Great advances in pre-clinical research can be expected using these models,” the team said.

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But other voices warned of a potential ethics storm, brewed by fears that technology used on our closest animal relatives could be turned to create genetically-engineered humans.

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In a study published in the British journal Nature, a team led by Erika Sasaki of the Central Institute for Experimental Animals at Keio University reported on experiments on common marmosets (Callithrix jacchus), a small monkey native to Brazil.

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They introduced a foreign gene, tucked inside a virus, into marmoset embryos that were then nurtured in a bath of sucrose.

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The gene codes for green fluorescent protein (GFP), a substance that was originally isolated from a jellyfish and is now commonly used as a biotech marker. An animal tagged with GFP glows green when exposed to ultraviolet light, proving that a key gene sequence has been switched on.

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The transgenic embryos were then implanted in the uterus of seven surrogate mother marmosets.

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Three of recipients miscarried. The other four gave birth to five offspring, all of which carried the GFP gene.

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In two of these five, the GFP gene had been incorporated into the reproductive cells. A second generation of marmosets was then derived from one of the two.

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The work is important, because medical researchers have hankered for an animal model that is closer to the human anatomy than rodents.

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Mice and rats, genetically engineered to have the symptoms of certain human diseases, are the mainstay of pre-clinical lab work, in which scientists test their theories before trying out any outcome on human volunteers.

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But many disorders, especially neurological diseases such as Alzheimer’s and Parkinson’s, are so complex that they cannot be reproduced meaningfully in rodents because their biology is different.

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Hopes for a non-human primate model have until now been dashed by the failure to insert a gene into a monkey’s sperm and eggs — the “germline” that ensures that the inserted DNA is passed on to future generations rather than lost.

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The first genetically-modified monkey was born in 2000. Known as ANDi (the initials of “Inserted DNA,” spelt backwards), the rhesus carried the GFP gene but not in its reproductive cells.

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The latest exploit thus opens up hopes of eventually breeding colonies of transgenic primates with inherited traits that closely replicate human disease.

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“This is the first case ever established in the world that an introduced gene was successfully inherited (by) the next generation in primates,” the researchers said in a press relase.

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Future plans include creating transgenic marmosets that replicate human diseases such as Parkinson’s and amyotrophic lateral sclerosis.

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In a commentary also published by Nature, Gerald Schatten and Shoukhrat Mitalipov, primate research specialists in the US, praised the achievement as “undoubtedly a milestone” but sounded caution.

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They said marmosets were not as useful as baboons or rhesus monkeys in replicating some diseases, notably HIV and tuberculosis.

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Another question was the random insertion of a foreign gene in the monkey’s genetic code. This may have caused some of the miscarriages and, if previous research is a guide, could unleash cancer.

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Scientists also have to address legitimate public concern about animal welfare and the need for “realistic policies” to prevent genetically-engineered babies, they warned.

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“There are many unanswered questions,” Helen Wallace, of GeneWatch UK, a British NGO that monitors the ethics of gene research, said.

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“It’s a big step from making a fluorescent green marmoset to making a marmoset that replicates a human disease, it’s a much more complicated thing to do.

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“There’s also a very important ethical debate, firstly about the animals themselves and secondly about what this might lead to in the future, whether it might be ethically justified to genetically engineer humans.”

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