Ferreting out the Details of Reproductive Cloning


By Allison Kubo Hutchison 

Elizabeth Ann, the first cloned black-footed ferret taken on Jan 29,2021. U.S. Fish and Wildlife Service via AP.
Although all births are special and joyous occasions, on December 10, 2020, researchers celebrated the birth of an extraordinary ferret kit. Elizabeth Ann, born from a domestic ferret surrogate, is not biologically related to her birth mother. She is a clone of the endangered black-footed ferret, a wild US-native species. The ferret she was cloned from died in 1988.

Elizabeth Ann is the first US-native endangered species to be cloned. The black-footed ferret was thought completely extinct due to habitat loss until a small colony was discovered in 1981. Conservationists engaged in a captive breeding program to preserve the species but only seven females were able to reproduce meaning that 40 years later all the approximately 1,000 remaining black-footed ferrets have a limited gene pool. The lack of genetic diversity leaves the population susceptible to diseases. Elizabeth Ann is the first step to introducing a new line into the family tree. After her predecessor, Willa, died in 1988 her remains were frozen at the San Diego Zoo’s “frozen zoo” facility.

The embryo that split and multiplied to become Elizabeth Ann was created using a process called somatic nuclear transfer. First, an egg is removed from a female and the chromosomes of the egg are removed. This leaves an egg cell empty with all the packaging but lacking the instructions. Then a nucleus from the non-reproductive cells of the genetic donor which could be skill cells or fat cells is removed. Then the nucleus from the animal you wish to clone is inserted into the empty egg. Finally, the egg is stimulated to grow using a small shock and it will begin to split and divide like a normal embryo and will be implicated into a surrogate mother for gestation. There are limitations to this method and it has had limited success due to high fetal and neonatal death rates. In addition, there have been developmental disorders observed in some of the cloned animals.

It is important to note that these animals are not true carbon copies of the original. If an egg is used from a different individual the mitochondrial DNA will not be the same even if the nuclear DNA is. This occurs because the mitochondrial comes from the original egg cell and is not replaced. However, they will be 100% the same if an egg from the cloned animal is used. The egg used for Elizabeth Ann was from a domestic ferret.

Elizabeth Ann aid the efforts of the U.S. Fish and Wildlife Service, Revive & Restore, ViaGen Pet & Equine, San Diego Zoo Global, and the Association of Zoos and Aquariums to restore the black-footed ferret species.

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