Understanding Biotechnology

What is Biotechnology

Overview of Biotechnology

History of Biotechnology

Why do we do biotechnology?

Biotechnology for the environment

Biotechnology for food and agriculture

But, what about those species which have already become extinct? Specimens of these animals (and their DNA) can sometimes be found in alcohol-filled preserving bottles in museum storerooms. Is cloning likely to help resurrect these species?

Cloning is a very inefficient process. Even in the Hawaiian laboratory of Professor Ryuzo Yanagimachi, where the best results have been achieved so far, only 3% of cloned mice embryos survive to birth.

This laboratory has the best possible conditions for mouse cloning and all the relevant knowledge available on the timing of reproduction. In addition, many females can be treated to receive the embryos at the appropriate time in their reproductive cycle.

The laboratory of Professor Yanagimachi now has a population of about 80 cloned mice. These have been cloned using nuclei from tissues including nerves, tail tips and the diffuse cloud of cells which surrounds recently ovulated eggs.

Extracting DNA from an insect trapped in amber, as in Jurassic Park, is a very long way from making a real dinosaur. Despite successful efforts extracting bacteria from insects preserved in amber, it is still only speculation that we could ever extract DNA from the blood sucked by mosquitoes from dinosaurs millions of years ago. Big leaps of technology and skill are still required before creating a dinosaur could be contemplated.

The thylacine: a case study

For both these specimens, the first stage of the process — extracting DNA samples from the preserved tissue — has been achieved. From there the going gets tougher, even though the starting materials are far better than those available for the dinosaur cloning seen in the movie Jurassic Park.

In 1999, DNA was successfully extracted from an ethanol‑preserved Tasmanian tiger pup sample. In 2001, additional DNA was extracted from two other pups using tissue from bone, tooth, bone marrow and dried muscle.

In 2002, the Evolutionary Biology Unit at the Australian Museum in Sydney successfully replicated individual Tasmanian tiger genes using a process known as PCR. The next stage would have been to make copies of all the genes of the Tasmanian tiger to construct synthetic chromosomes. However, in 2005, the project was abandoned, because the DNA was found to be too degraded to work with effectively.

Producing viable embryos would be too difficult — perhaps even impossible — using the DNA preserved through freezing or in alcohol, as it is often damaged. Given the low efficiency of mouse cloning experiments, in which intact nuclei from living cells were used as the source of DNA for cloning, the likelihood of being able to clone an animal from a preserved specimen is extremely low with current technology.

Even if the difficulties with the technology were overcome, individuals produced from this alcohol-preserved specimen would all have exactly the same genetic make-up and would be the same sex — unless new genes could be artificially introduced into DNA from a thylacine in a museum.

All science is carried out in a social and economic context. A group of individuals like this could not make up a viable population. The idea of a lone and lonely mammoth or thylacine in a zoo or wildlife park is of concern to wildlife managers and to the community.

In 2008, scientists from the University of Melbourne extracted DNA from a 100-year-old thylacine pouch young specimen at the Victoria Museum. They managed to incorporate a small piece of DNA involved in the regulation of bone development genes into the genome of a mouse. The thylacine DNA functioned normally in the mouse cells. It was the first time that DNA from an extinct species has ever been used to induce a biological function in another living organism.

This type of work shows that even if a species is extinct, its genetic information is not lost. The function of genes from extinct animals can still be determined, revealing information about the evolutionary relationships of the animals and about how the particular genes evolved their particular functions.