Resurrect extinct animals

"Production of healthy cloned mice from bodies frozen at -20 degrees C for 16 years"
http://www.ncbi.nlm.nih.gov/pubmed/18981419

Dr Wakayama and colleagues, Japanese scientists at RIKEN research institute, produced cloned mice from frozen carcasses. These dead mice had been kept frozen at -20 degrees C for 16 years without any cryoprotective treatment. Freezing inevitably causes cell burst and DNA damage inside. Using a modified cloning method by nucleus transfer, the team succeeded in producing healthy mice from the cloned embryos.

Recently, several studies have reported regarding reproductive cloning of endangered species.
Scientists at Advanced Cell Technology, a biotechnology company in Massachusetts, first reported the cloning of an endangered animal in 2001. They cloned a gaur, an Indian wild cattle, using nuclei of skin cells frozen for eight years. However, the cloned gaur, named noah, died from an infection two days after its birth. After Noah, a number of endangered animals have cloned by same nucleus transfer techniques. These studies used cryoprotected cells for the cloning, whereas Wakayama's team enabled using nuclei from dead and degraded cells. Their study will open the way to "resurrect" extinct animals, such as mammoths.

In Australia, scientists at the Australian Museum attempted to resurrect Tasmanian tiger (thylacine), a wolf-like marsupial, from the specimens. However, since the DNA retains too less quality, they forced to give up the attractive project. In a recent report, researchers from the Australia and USA isolated a transcriptional enhancer element from the specimens and resurrected the functions in transgenic mice (http://www.ncbi.nlm.nih.gov/pubmed/18493600). A professor in the team says that their work proved possible to study the functions of genes from extinct species, although cloning of a thylacine is still a long way off.

In Japan, Japanese toki (Japanese crested ibis) has become extinction in 2003. Since the tissues and cells from the last one were frozen for preservation, it appears to be easier to resurrect this extinct bird than other extinct animals.

Theoretically, the techniques are applicable to reproductive cloning of humans. In 1991, a frozen 5,300-year-old Neolithic man was discovered in the Austrian Alps. On the other hand, bodies of some presidents of Communist governments, such as Vladimir Lenin, Kim Il-sung and Mao Zedong, were embalmed after their death. Although it would be difficult to obtain intact DNA from these preserved corpses, the study by Wakayama's team might stimulate some scientists of resurrecting them.