Frozen zoo

Source: Wikipedia, the free encyclopedia.

A frozen zoo is a storage facility in which genetic materials taken from animals (e.g.

embryos and live tissue) are stored at very low temperatures (−196 °C) in tanks of liquid nitrogen.[1] Material preserved in this way can be stored indefinitely[2] and used for artificial insemination, in vitro fertilisation, embryo transfer, and cloning
. Some facilities also collect and cryopreserve plant material (usually seeds).

The first frozen zoo was established at the

Gathering material for a frozen zoo is rendered simple by the abundance of

Scripps Research Institute has successfully made skin cells into cultures of special cells called induced pluripotent stem cells (IPS cells). It is theoretically possible to make sperm and egg cells from these IPS cells.[4]

Several animals whose cells were preserved in frozen zoos have been cloned to increase the genetic diversity of endangered species, as of 2021. One attempt to clone an extinct species was made in 2003; the newborn Pyrenean ibex died of a development disorder which may have been linked to the cloning, and there are not enough genetic samples in frozen zoos to re-create a breeding Pyrenean ibex population.

Existing frozen zoos

The Frozen Zoo at the San Diego Zoo's Institute for Conservation Research currently stores a collection of 8,400 samples from over 800 species and subspecies.[12] Frozen Zoo at San Diego Zoo Conservation Research has acted as a forbearer to similar projects at other zoos in the United States and Europe.[13][14] However, there are still less than a dozen frozen zoos worldwide.[2]

At the United Arab Emirates'

Gordon’s wildcat (Felis silvestris gordoni) and the Arabian leopard (Panthera pardus nimr) (of which there are only 50 in the wild).[11]

The Audubon Center for Research of Endangered Species, affiliated with the University of New Orleans, is maintaining a frozen zoo. In 2000 the Center implanted a frozen-thawed embryo from the highly endangered African wildcat into the uterus of a domestic house cat, resulting in a healthy male wildcat.[15]


London Natural History Museum, and the University of Nottingham.[16][17]

The University of Georgia's Regenerative Bioscience Center is building a frozen zoo. RBC Director Steven Stice and animal and dairy science assistant professor Franklin West created the facility with the thought of saving endangered cat species. The scientists have already extracted cells from a Sumatran tiger, which could be used for artificial insemination. Artificial insemination provides a remedy for animals who, due to anatomical or physiological reasons, are unable to reproduce in the natural way. Reproduction of stored genetic material also allows for the fostering of genetic improvements, and the prevention of inbreeding. Modern technology allows for genetic manipulation in animals without keeping them in captivity. However, the success of their restoration into the wild would require the application of new science and a sufficient amount of previously collected material.[11]



A gaur that died of natural causes had some skin cells frozen and added to the San Diego Frozen Zoo. Eight years later, DNA from these cells was inserted into a domestic-cow egg to create an embryo (trans-species cloning), which was then implanted in a domestic cow (Bos taurus). On 8 January 2001, the gaur, named Noah, was born in Sioux Center, Iowa. Noah was initially healthy, but the next day, he came down with clostridial enteritis, and died of dysentery within 48 hours of birth. This is not uncommon in uncloned animals and the researchers did not think it was due to the cloning.[18]



Caesarian section. The first was born on 1 April 2003, and the second two days later. The second was euthanised, apparently suffering from large offspring syndrome (an overgrowth disorder), but the first survived and lived for seven years at the San Diego Zoo, where it died in April 2010 after it broke a leg and was euthanised.[21][22]

Przewalski's horse clone

In 2020, the first cloned

San Diego Zoo Global, ViaGen Equine and Revive & Restore.[23] The cloning was carried out by somatic cell nuclear transfer (SCNT), whereby a viable embryo is created by transplanting the DNA-containing nucleus of a somatic cell into an immature egg cell (oocyte) that has had its own nucleus removed, producing offspring genetically identical to the somatic cell donor.[24] Since the oocyte used was from a domestic horse, this was an example of interspecies SCNT.[25]

The somatic cell donor was a Przewalski's horse stallion named Kuporovic, born in the UK in 1975, and relocated three years later to the US, where he died in 1998. Due to concerns over the loss of

cryopreserved at the San Diego Zoo's Frozen Zoo. Breeding of this individual in the 1980s had already substantially increased the genetic diversity of the captive population, after he was discovered to have more unique alleles than any other horse living at the time, including otherwise-lost genetic material from two of the original captive founders.[23] To produce the clone, frozen skin fibroblasts were thawed, and grown in cell culture.[26] An oocyte was collected from a domestic horse, and its nucleus replaced by a nucleus collected from a cultured Przewalski's horse fibroblast. The resulting embryo was induced to begin division, and was cultured until it reached the blastocyst stage, then implanted into a domestic horse surrogate mare,[26]
which carried the embryo to term and delivered a foal with the Przewalski's horse DNA of the long-deceased stallion.

The cloned horse was named Kurt, after Dr. Kurt Benirschke, a geneticist who developed the idea of cryopreserving genetic material from species considered to be endangered. His ideas led to the creation of the Frozen Zoo as a genetic library.[27] There is a breeding herd in the San Diego Zoo Safari Park.[28] Once the foal matures, he will be relocated to the breeding herd at the San Diego Zoo Safari Park,[29] so as to pass Kuporovic's genes into the larger captive Przewalski's horse population and increase the genetic variation of the species.[23]

Black-footed ferret

Elizabeth Ann, the first cloned black ferret, being weighed on the 18th of February 2021 (at 70 days old)

The cells of two 1980s wild-caught black-footed ferrets that never bred in captivity were preserved in the San Diego Wildlife Alliance Frozen Zoo. One of them was cloned to increase genetic diversity in this species in December 2020. More clones of both are planned. They will initially be bred separately from the non-cloned population.[30]

Pyrenean ibex

The Pyrenean ibex went extinct in 2003. In 2003 frozen cells from the last one (a male killed by a falling branch) were used to clone 208 embryos, of which 7 successfully implanted in goats, and one made it to term. That one ibex died of respiratory failure just after birth; quite possibly as a result of the cloning process, its lungs had not developed properly. There may not be enough individuals' cells preserved to create a breeding population.[31][32]

See also


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  2. ^ a b c "Frozen Zoo". Audubon Nature Institute. Retrieved 2010-04-28.
  3. ^ Williams, Shawna (September 14, 2018). "Conservation Biologist and Placenta Expert Kurt Benirschke Dies; He established the San Diego Zoo's cryopreserved Frozen Zoo". The Scientist. Retrieved 2 December 2018.
  4. ^ a b Harris, Paul (August 28, 2010). "The Frozen Zoo aiming to bring endangered species back from the brink". The Guardian. Retrieved 2 December 2018.
  5. ^ Dan Collins (2002-10-14). "San Diego's Frozen Zoo". The Associated Press and CBS News. Retrieved 2010-04-28.
  6. ^ Squarci, Gaia; Cornet, Laurence (February 28, 2017). "Extinct animals find new futures at the 'frozen zoo'". Mashable. Retrieved 2 December 2018.
  7. ^ Gregory Benford, Nov, 15, 1992. "Saving the Library of Life"
  8. ^ "Species Survival Center". Audubon Nature Institute. Retrieved 2010-04-28.
  9. ^ Margit Kossobudzka (2002-10-14). "Wyginął, a teraz powraca". Gazeta Retrieved 2010-04-26.
  10. ^ Jan Sochaczewski (2007-10-12). "Zamrożone mamuty powrócą do świata żywych". Retrieved 2011-02-20.
  11. ^ a b c F.J. de Haas van Dorsser MA VetMB MRCVS. "The Frozen Zoo: Breeding Centre for Endangered Arabian Wildlife, Sharjah, UAE". Arabian Wildlife. Archived from the original on 2010-05-21. Retrieved 2010-04-26.
  12. ^ "Chill Out: Frozen Zoo Aiding Conservation Projects". San Diego Zoo. Retrieved 2010-04-26.
  13. ^ "Scientific Meeting - The Frozen Ark Project". ZSL London Zoo. Archived from the original on 2010-10-23. Retrieved 2010-04-26.
  14. ^ "Welcome to the Frozen Ark". The Frozen Ark Project. Archived from the original on 2015-12-11. Retrieved 2010-04-26.
  15. ^ "The Frozen Zoo: The University Of New Orleans And The New World Of Saving Endangered Species". Science Daily. March 12, 2001. Retrieved 2 December 2018.
  16. ^ Kettlewell, Julianna (27 July 2004). "'Frozen Ark' to save animal DNA". BBC News. Retrieved 19 July 2010.
  17. ^ Johnstone, Helen (27 July 2004). "Endangered species gain a place on Frozen Ark". The Telegraph. Archived from the original on 18 January 2010. Retrieved 19 July 2010.
  18. ^ Advanced Cell Technology, Inc. (2001). "Press Release – First cloned endangered animal was born at 7:30 pm on Monday, 8 January 2001". Archived from the original on 31 May 2008.
  19. S2CID 12907904
  20. ^ "Banteng clone leads charge for endangered animals". The Sydney Morning Herald. 9 April 2003. Retrieved 12 May 2020.
  21. ^ "Collaborative effort yields endangered species clone". Advanced Cell Technology. 8 April 2003. Archived from the original on 23 October 2006.
  22. ^ Ro, C. "The increasingly realistic prospect of 'extinct animal' zoos". BBC. Retrieved 12 May 2020.
  23. ^ a b c "Przewalski's Horse (Takhi) Project | Revive & Restore". Retrieved 2020-11-15.
  24. PMID 14614770
  25. .
  26. ^ a b "About Cloning | Revive & Restore". Retrieved 2020-11-15.
  27. ^ "Kurt Benirschke (1924-) | The Embryo Project Encyclopedia". Retrieved 2020-11-15.
  28. ^ Beale, Mel (10 June 2021). "Why a cloned foal born at a USA zoo is key to the survival of his endangered breed". Your Horse.
  29. ^ Beale, Mel (10 June 2021). "Why a cloned foal born at a USA zoo is key to the survival of his endangered breed". Your Horse.
  30. ^ "Black-footed Ferret Project - Revive & Restore". Retrieved 24 October 2021.
  31. ^ "First Extinct-Animal Clone Created". Science. 10 February 2009. Retrieved 24 October 2021.
  32. ^ "The Perils of De-extinction". Center for Humans & Nature. 4 July 2017. Retrieved 24 October 2021.