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Effort afoot to freeze animal reproductive cells at Yokohama zoo

by

Staff Writer

From humboldt penguins to black jaguars, sperm and eggs from dozens of zoo animals are being frozen and stored at the Zoorasia Yokohama Zoological Gardens until they can be used for artificial insemination.

Placed in thin tubes, the reproductive cells taken from over 50 different species raised in three zoos — Kanazawa Zoo, Nogeyama Zoo and this one — in Yokohama are stored in tanks and frozen with minus-196 degrees Celsius liquid nitrogen.

“Theoretically speaking, the frozen sperm and eggs can be preserved semipermanently,” said Noriyoshi Ichikawa, director of the Yokohama-run Preservation and Research Center at the zoo that stores the cells.

“If we preserve these gametes now, they could be used in the future” if the species face extinction, he added.

Dubbed Frozen Zoo, the initiative is part of conservation efforts that Japanese zoos have pursued in recent years, hoping to help breed animals that may disappear from their facilities in the future, and possibly to save endangered species in the wild.

Apart from Yokohama zoo, Tama Zoological Park in Tokyo and Kobe University, which initially launched the research in the early 1990s, have frozen zoos.

And a new one is also slated to be created in Sendai Yagiyama Zoological Park in Miyagi Prefecture by the end of the current fiscal year in March 2016.

The Yokohama preservation center also began storing frozen reproductive cells from the Japanese Association of Zoos and Aquariums (JAZA) in March of last year.

Though zoos in Japan have long been perceived merely as recreational facilities, that image has changed in recent years, Ichikawa said. Visitors are more aware of the importance of conservation and understand the role zoos play in that field, he said.

“I believe Japanese zoos lag 10 years behind those in Western countries,” Ichikawa said. “But we are now beefing up efforts to preserve wildlife.”

Behind their efforts to preserve the cells is a rising concern that rare animals will disappear from zoos in the near future.

According to estimates by JAZA in 2011, the number of African elephants at Japanese zoos would shrink to seven in 2030 from 65 in 2000, and the number of gorillas would drop to six from 33.

As trade in wild animals is strictly restricted under the Convention on the International Trade in Endangered Species of Wild Fauna and Flora, known as the Washington Convention, today most of the animals seen in the nation’s zoos were bred in Japan. Although zoos have worked hard at efforts to breed animals, some species may disappear from the facilities, experts say.

Among some 76,000 assessed species around the world, about 22,000 were threatened with extinction as of 2014, according to the International Union for Conservation of Nature, a Switzerland-based global environmental organization.

“Wild animals are disappearing at a very fast rate,” Ichikawa said. “I hope to see more of this kind of facility in Japan so we can preserve gametes taken from local zoos in each region.”

However, using the frozen cells could take a very long time, given that the technology needed to do so doesn’t exist yet, experts say.

Hiroshi Kusunoki, an associate professor at Kobe University who initiated research to freeze the cells in Japan, said they have yet to establish effective ways to freeze sperm and eggs to be used later for artificial insemination.

“It’s really hard to resurrect (reproductive cells) after (thawing) them. And freezing tolerance is different between animals,” he said.

Even if they succeed in establishing techniques for resurrecting the cells in a healthy state, hurdles still remain, as they have yet to develop artificial insemination techniques for most species.

In Japan, researchers have succeeded only a few times in artificial insemination using frozen sperm, including those of a chimpanzee and a lion, experts said.

“When it is hard to even remove sperm or eggs from living animals, putting a fertile egg back into a female would be very difficult,” Kusunoki said.

The shapes of ova and the length of pregnancy differ between animals, he said, adding that he has yet to gain a full understanding of the process.

And above all, collecting eggs is very difficult, he said. Researchers usually remove sperm or eggs as soon as animal dies. But the chances of gaining healthy and useful reproductive cells from aged animals are slim, Kusunoki said.

Sperm can also be taken from live animals by making them ejaculate using electrical stimulus, according to Ichikawa of the preservation center in Yokohama. But in the case of eggs, the only option is to remove them from carcasses, as anesthetizing living animals to remove their eggs puts their lives at risk, Ichikawa said.

“I probably have to live 100 or 200 more years” to see the development of the necessary technologies, Kusunoki said.

But if they freeze the cells now, future generations might be able to use them for artificial insemination some day, he said.

The question is whether there would be a hospitable environment where these animals can live 100 years from now, and whether people will want to use frozen cells in the future.

“The important thing for us to do now is to stop destroying nature, and to convey to children our view” that preserving nature is important, Kusunoki said.