Scientists Create 581 Clones From Same Mouse

5,803 5 Loading

[Source: Wikpedia]

[Source: Wikpedia]

Scientists in Japan have taken cloning to a whole new level. They haven’t cloned a new species or even come up with a new technique. They have, however, managed to push the technique to new limits by cloning 581 mice – all from a single original cell. If their results can be replicated in other animals it could provide a way for virtually unlimited supplies of genetically superior farm animals or other animals important to research.

Long before Dolly was cloned in 1996, scientists had already established a long history of cloning mammals. The first was a genetically identical mouse produced in 1979. Shortly thereafter the first genetically identical cows, chickens, and sheep were produced. What made Dolly a sensation, however, was the method by which she was cloned. Whereas the mammalian clones before her were produced by splitting an embryo in a test tube and then implanting them in surrogate mothers, Dolly was cloned from an adult cell. To be specific, an udder cell taken from a 6-year-old sheep. The cloning method, called somatic cell nuclear transfer (SCNT), involves taking the genetic material from the adult cell and placing it in the nucleus of an egg that has had its own genetic material removed.

Somatic cell nuclear transfer involves inserting genetic material from an adult cell into an enucleated egg. [Source: Wikipedia]

Somatic cell nuclear transfer involves inserting genetic material from an adult cell into an enucleated egg. [Source: Wikipedia]

After Dolly, scientist have used SCNT to clone other mammals including cat, dog, deer, horse, mule, ox, rabbit and rat. That’s significant progress for a technique that Ian Wilmut had to employ 276 times before finally succeeding in cloning Dolly. But today’s scientists aren’t content to just clone once. For several years now attempts have been made to derive as many clones as possible from that one original piece of genetic material.

But there’s been problems. With each round of SCNT recloning, researchers quickly discovered, success rates dropped. In a study performed in 2000, the authors of the current work were able to clone a mouse to the sixth generation – but just barely. That final generation required more than 1,000 SCNT attempts and the sole pup that was born was promptly cannibalized by its mother. Repeatedly cloning cattle and cats went no further than the third generation.

Frustrated scientists attempted to find out why successive cloning was progressively problematic. They found that the original cell from which the clones were ultimately derived often had ‘epigenetic’ abnormalities. Epigenetic regulation refers to the turning on and off of genes by molecules, not the genes themselves. Any random cell could reasonably be expected to have some epigenetic abnormalities, but when all of the organism’s cells are derived from the same cell, whatever abnormalities that cell has will be magnified. For example, a series of cloned mice were shown to express an RNA molecule that inactivated one of the female’s X chromosomes. When the RNA molecule was removed cloning efficiency of the mice increased nearly nine-fold.

Dr. Teruhiko Wakayama and colleagues used an epigenetic inhibitor to improve cloning efficiency to an unprecedented level. [Source: RIKEN]

Dr. Teruhiko Wakayama and colleagues used an epigenetic inhibitor to improve cloning efficiency to an unprecedented level. [Source: RIKEN]

Based on previous work, the Japanese researchers sought to improve their cloning efficiency by using a chemical called trichostatin A that inhibits the powerful epigenetic protein histone deacetylase. In an experiment that was begun in 2005, the inhibitor allowed them to produce 581 mice through 25 rounds of SCNT cloning. The mice were healthy and were able to reproduce. What’s more the cloning success rate did not decrease with each generation.

The study, led by Dr. Teruhiko Wakayama at the RIKEN Center for Developmental Biology in Japan, was published in the March 7 issue of Cell Stem Cell.

If the inhibitor is equally effective in other animals, the technique opens up the possibility of cloning highly-valued animals such as prized cattle or racehorses, or genetically modified animals used in medical research. As the authors note in the study: “Our results show that repeated iterative recloning is possible and suggest that, with adequately efficient techniques, it may be possible to reclone animals indefinitely.”

That’s good news for those that have already turned to cloning to create a small pack of super sniffing inspector dogs at airports, cows that produced humanized milk, even Olympic horses. Cloning remains a young science and scientists no doubt have a long list of organisms they would like to clone. If the current technique means limitless return on one’s cloning efforts, it could entice more scientists to take the first step, and bring cloning from the fringes of science to the mainstream.

Peter Murray

Peter Murray was born in Boston in 1973. He earned a PhD in neuroscience at the University of Maryland, Baltimore studying gene expression in the neocortex. Following his dissertation work he spent three years as a post-doctoral fellow at the same university studying brain mechanisms of pain and motor control. He completed a collection of short stories in 2010 and has been writing for Singularity Hub since March 2011.

Discussion — 5 Responses

  • rtryon March 24, 2013 on 1:30 pm

    Does this mean that we should turn on or off the DNA that makes gays and lesbians in all fetal developing situations? Or only as selected by parents of same sex marriage or heterosexual combinations?

    • Robert Cunningham rtryon April 12, 2013 on 8:24 am

      ….ummmm no! Why the hell would it mean that?

    • Robert Cunningham rtryon April 12, 2013 on 8:34 am

      Also that question presumes that there is one aspect to homosexuality, that sexuality is fixed, and that it is all biology – as if it isn’t a complicated mixture of neuro-wiring, hormones, available socially constructed identities, cultural pressures & influences etc. There is no reason to believe that it is even possible to ‘turn off’ the stuff that creates diverse and ever-changing sexualities. Nor have you or anyone else provided justification for ever doing so.

      Also, what is a parent of same-sex marriage? People don’t have to be married or even be a couple to have children. Same-sex couples don’t necessarily want same-sex-loving children and heterosexual couples don’t necessarily want heterosexual children.

      Sexuality is also more diverse than the binary options that you provided. Everything about your question is ignorant. Please go read.

  • Hassan Davis April 1, 2013 on 11:50 am

    The benfits have been listed. However, does this not drive down genetic diversity? What are the drawbacks of that happening?

  • Babu Ranganathan April 17, 2013 on 9:08 am

    HOW DO EGG YOLKS BECOME CHICKENS? (Internet Article) When you divide a cake, the parts are smaller than the original cake and the cake never gets bigger. When we were a single cell and that cell divided, the new cells were the same size as the original cell and we got bigger. New material had to come from somewhere. That new material came from food. The sequence in our DNA directed our mother’s food, we received in the womb, to become new cells forming all the tissues and organs of our body. Understand how DNA works. Read my Internet article: HOW DO EGG YOLKS BECOME CHICKENS? Just google the title to access the article.

    This article explains how DNA works and will give you a good understanding of DNA, as well as cloning and genetic engineering.

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    Babu G. Ranganathan
    (B.A. Bible/Biology)