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Freeze-dried mice: How a new technique could help conserve the species

Japanese scientists who have successfully produced cloned mice using freeze-dried cells they believe may one day aid in the conservation of the species and address the challenges with existing biobanking methods.

The United Nations has warned that extinction is accelerating worldwide and at least one million species could disappear due to human-induced impacts such as Climate change,

Facilities have grown globally to preserve specimens of endangered species with the goal of preventing extinction by future cloning.

These samples are typically cryopreserved using liquid nitrogen or kept at extremely low temperatures, which can be costly and vulnerable to power outages.

they usually also include Sperm and egg cells, which may be difficult or impossible to harvest from older or infertile animals.

Scientists at Japan’s Yamanashi University wanted to see if they could solve those problems by freeze-drying somatic cells — any cells that are not sperm or egg cells — and attempting to clone them.

They experimented with two types of mice cells, and found that, while freeze-drying killed them and caused significant DNA damage, they could still generate cloned blastocysts – a ball of cells that developed into an embryo. .

From these, the scientists extracted stem cell lines from which they created 75 cloned mice.

One of the mice lived for a year and nine months, and the team also successfully mated female and male cloned mice with naturally born partners and produced normal puppies.

The cloned mice produced fewer offspring than the naturally bred mice, and one of the stem cell lines developed from male cells only produced clones of female mice.

“The improvement shouldn’t be difficult,” said Professor Teruhiko Wakayama of Yamanashi University’s Faculty of Life and Environmental Sciences, who helped lead the study published this month in the journal Nature Communications.

“We are confident that in the future we will be able to reduce abnormalities and increase birth rates by discovering freeze-drying protectant agents and improving drying methods,” he told AFP.

“We have made a breakthrough in this area”

There are some other drawbacks – the success rate of cloning mice from cells stored in liquid nitrogen or at ultra-low temperatures is between 2 and 5 percent, while the freeze-dried method is only 0.02 percent.

But Wakayama says the technology is still in its early stages, comparing it to a study that produced the famous sheep clone “Dolly” — a breakthrough after more than 200 attempts.

“We believe that most importantly, cloned mice are generated from freeze-dried somatic cells, and we have made a breakthrough in this area,” he said.

While the method is unlikely to completely replace cryopreservation, it represents “a very exciting advance for scientists interested in biobanking for global biodiversity,” according to the Center for Conservation Ecology and Genomics at the University of Canberra. Senior research fellow Simon Clulow said.

“Working on cryopreservation protocols can be difficult and expensive, and so alternatives, especially those that are cheap and robust, are very welcome,” Clulow said.

The study stored freeze-dried cells at minus 30 degrees Celsius, but the team has previously shown that freeze-dried mouse sperm can survive at least a year at room temperature and believe that Somatic cells will do the same.

The technology could eventually allow “genetic resources from around the world to be stored cheaply and safely,” Wakayama said.

The work is an extension of years of research by Wakayama and his colleagues on cloning and freeze-drying techniques.

One of his recent projects involved freeze-drying mouse sperm that were sent to the International Space Station. Even after six years in space, the cells were successfully reinserted back to Earth and produced pups of healthy mice.

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