How a new technique can help with conservation?

Wakayama's team has previously used freeze-dried mouse sperm sent into space to produce mouse pups

Wakayama’s team has previously used freeze-dried mouse sperm that was sent into space to produce mouse pups.

Japanese scientists have successfully produced cloned mice using freeze-dried cells in a technique they believe could one day help conserve species and overcome challenges with current biobanking methods.

The United Nations has warned that extinction is accelerating worldwide and that at least a million species could disappear as a result of man-made effects such as climate change

Facilities have sprung up worldwide to hold samples from: endangered species with the aim of preventing its extinction from future cloning.

These samples are generally cryopreserved using: liquid nitrogen or stored at extremely low temperatures, which can be costly and vulnerable to blackouts

They usually also include sperm and eggsthat are difficult or impossible to harvest from old or barren animals.

Scientists from Japan’s Yamanashi University wanted to see if they could solve those problems by freeze-drying them Somatic cells-any cell that is not a sperm or egg – that tries to produce clones.

They experimented with two types of mouse cells and found that although they were killed by freeze-drying and caused significant DNA damage, they could still produce cloned blastocysts — a ball of cells that develop into an embryo.

From this, the scientists extracted stem cell lines that they used to make 75 cloned mice.

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

The cloned mice produced fewer offspring than would have been expected from naturally born mice, and one of the stem cell lines developed from male cells produced only female mouse clones.

“Improving shouldn’t be difficult,” said Teruhiko Wakayama, a professor in the University of Yamanashi’s Faculty of Life and Environmental Sciences, who helped lead the study published in the journal nature communication this month.

“We believe that in the future we can reduce variances and improve the birth rate by looking for freeze-drying protectants and improving drying methods,” he told AFP.

‘Very exciting advance’

There are some other drawbacks: the chance of success of mouse cloning from cells stored in liquid nitrogen or at ultra-low temperatures is between two and five percent, while the freeze-dried method is only 0.02 percent.

But Wakayama says the technique is still in its infancy, comparing it to the study that produced the famous sheep clone “Dolly” — a single success after more than 200 attempts.

“We believe that the most important thing is that cloned mice are produced from freeze-dried body cells, and we have achieved 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, the endangered global biodiversity,” said Simon Clulow, senior research fellow at the Center for Conservation Ecology and Genomics at the United Nations. University of Canberra.

“It can be difficult and expensive to establish cryopreservation protocols, so alternatives, especially cheaper and more robust ones, are very welcome,” added Clulow, who was not involved in the study.

The study stored the freeze-dried cells at minus 30 degrees Celsius, but the team has previously shown that freeze-dried mouse sperm can survive for at least a year at room temperature and believes somatic cells would too.

The technique 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 into cloning and freeze-drying techniques by Wakayama and his partners.

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

Japanese scientists develop postcards with freeze-dried mouse sperm

More information:
Sayaka Wakayama, healthy cloned offspring derived from freeze-dried body cells, nature communication (2022). DOI: 10.1038/s41467-022-31216-4.

© 2022 AFP

Quote: Freeze-Dried Mice: How a New Technique Could Help Preservation (2022, July 5) Retrieved July 5, 2022 from

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