Why is there a rhino in the freezer?

In the basement of the Natural history museum there is a rhino in the freezer. Packed in custom designed vials, tissue and blood samples from endangered species across the globe lie in liquid nitrogen freezers. Despite the comical names and photos used to refer to each of the freezers, the dedicated team who monitor these have a serious role in conservation of some the most vulnerable species on the planet. But how can frozen samples in a museum basement help living animals from the Amazon rainforest or the Sahara desert?

The coldest open access library

Species are slipping towards extinction at an alarming rate, shown by groups like amphibians and corals in which  31-56%, and 27-44% assessed species are threatened respectively.1-2 With extinction the unique information and remarkable adaptations,1 evolved over millions of years is lost. This genetic information, is valuable in itself, but also could be the key to answering human questions on medicine, material design or even food security. The Frozen Arc is crucial to both preserving this information for the future, as well as making it accessible to scientists today,

The IUCN List of species survival shows rapid decreases in biodiversity over the last thirty years. 1 would be that no species are at risk of extinction, 0 would be total extinction, and a horizontal line unchanging extinction risk.  [Accessed 04/12/14]

The IUCN List of species survival shows rapid decreases in biodiversity over the last thirty years. 1 would be that no species are at risk of extinction, 0 would be total extinction, and a horizontal line unchanging extinction risk. ©IUCN Red List, Summary statistics [Accessed 04/12/14]

facilitating scientific studies which otherwise may not be feasible. Examples from the long running Frozen Arc project in San Diago3 include requests for cells to investigate aging, by looking at potential links between how animal longevity and DNA repair after UV damage. There are also requests for peculiar cells, like those from the Indian muntjac, which was found to have a very low chromosome number3. Indian muntjac cells are now used in a wide range of research contributing to cancer research and understanding fundamentals in cellular biology.

An usual source of romance

Inbreeding is a serious concern for the conservation of endangered animals2. Habitat fragmentation can often result in limited breeding opportunities in isolated populations2, and species with limited numbers in the wild or captivity may suffer from a lack of genetic diversity altogether. Habitat conservation and protection and provision of wildlife corridors between fragmented habitat patches are the key to effective conservation in these areas. However, when habitat protection projects are not immediately feasible, cryopreservation of sperm and eggs could be critical to preserving and managing genetic diversity in managed breeding projects to safeguard the species1,4 .

Monica the baby Indian rhino was born in Buffalo zoo following artificial insemination with frozen sperm from a rhino which had died ten years ago. © DailyMail(2014)

Monica the baby Indian rhino was born in Buffalo zoo following artificial insemination with frozen sperm from a rhino which had died ten years ago. © DailyMail(2014)

However, there are issues and drawbacks to cryopreservation for reproduction. Firstly is the issue of eggs2. Little success has been had in successfully cyropreserving eggs of fish, amphibians or many species of mammal, meaning often only male genetics can be maintained through sperm storage. Additionally, there is the issues and challenges of collecting the sperm or eggs from animals in the wild.

Cloning

One tool which can maintain both male and female genetics through cyropreservation is cloning1,4. This may seem counter intuitive, as aiding genetic diversity is not the same as producing more copies of the same animal. However, there are cases where individuals of a critically endangered species die or are killed before they have a chance to breed, or are unable to breed due to lack of opportunities or impotence2,4. In these cases, skin cells previously taken, and stored in facilities like the Frozen Arc could be cloned to help reduce loss of genetic diversity4. The protocols of cloning of domestic animals is well established, with the emergence of private companies who will offer to clone beloved pets or prized horses or cattle.  However, while in domestic animals the animal to be cloned, the surrogate mother, and egg donor are of the same species, with endangered animals it is often more feasible to use a related but more common species to provide the egg and act as mother. The only contribution needed from the endangered animal is genetic information that can be taken from a blood or tissue sample. Research into cats has been at the forefront of research into cloning for conservation exemplified by the birth of kittens of the African wildcat were born to a housecat5.

Jazz the African wildcat kitten born to a domestic housecat at the Audubon Institute in 1999 ©CBSNEWS(1999)

Jazz the African wildcat kitten born to a domestic housecat at the Audubon Institute in 1999 ©CBSNEWS(1999)

The availability of cloning technologies do present the question of the potential of bringing back extinct species in fact, in 2009 the Pyrenean ibex was the first animal to briefly become “de-extinct” for seven minutes before it died of lung problems4. However, despite its brief success, the project did highlight the potential of bringing back a species which had only recently been lost, with good DNA available.

However, in a time of mass loss of species, the suggestion of bringing back species which may have lost their habitat altogether rather than using resources to protect living species on the brink of extinction is controversial. Despite this, although now the resources or inclination may not be available to bring back species, the question of “de-extinction” does show how the Frozen Arc Project is an invaluable tool to potentially give future generations the choice of bringing back something  we lost during our lifetimes.

Conclusion

In conclusion,  the carefully monitored  freezers in the basement of the Natural History Museum and other institutions around the world, hold  critical and in some cases irreplaceable knowledge. Biological knowledge, which can facilitate cellular research in serious areas of human medicine, and also genetic knowledge, in the form of genetic variation which can be used to protect critically endangered species from inbreeding. But perhaps most importantly is the knowledge that future generations will have access to resources which could otherwise be lost forever. For all of these reasons, this project really does live up to its name as the Frozen Arc.

References

  1. Clarke AG (2009) The Frozen Ark Project: the role of zoos and aquariums in preserving the genetic material of threatened animals. International Zoo Yearbook 43: 222–230
  2. Comizzoli P, Songsasen N, Wildt DE (2010) Protecting and Extending Fertility for Females of Wild and Endangered Mammals. Cancer Treatment and Research. 2010 156: 87–100.
  3. Benirschke K. (1984) The Frozen Zoo Concept. Zoo Biology 3:325-328.
  4. Smits K, Hoogewijs M, Woelders H, Daels P, Van Soom A (2012) Breeding or Assisted Reproduction? Relevance of the Horse Model Applied to the Conservation of Endangered Equids. Reproduction in Domestic Animals 47(4) 239–248.
  5. Gómez MC, Pope E, Giraldo A, Lyons LA, Harris RF, King AL, Cole A, Godke RA, Dresser BL (2004) Birth of African Wildcat Cloned Kittens Born from Domestic Cats. Cloning and Stem Cells 6(3):247-257.
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