| Despite the initial
media hype and public interest associated with the concept of producing
a clone of the thylacine, one can readily see that the technological and
biological barriers that would need to be overcome to produce a viable
embryo are indeed immense.
In February 2005, the
Australian Museum made the decision to discontinue its involvement with
the thylacine cloning project. In a media statement by the museum's
current Director Frank Howarth and Assistant Director of Science &
Collections Dr. Les Christidis it notes: "Although the museum possessed
sufficient expertise to attempt to reconstruct a thylacine DNA library,
it lacked the facilities and skill to conduct further stages requiring
cell culture". The cell culture stage of the project is necessary
to enable cells from other species to act as hosts for the reconstructed
thylacine genome. Michael Archer, the project's team leader until
2003, when he left the museum to take up his new position as Dean of
Science at the University of New South Wales, said that he: "was
personally disappointed by the museum's decision not to proceed with the
project" (Skatssoon 2005). Archer
continued:
"I and other colleagues
remain interested in the project and I don't think that it will simply
die because the museum can't proceed. The technology to make it happen
is improving all the time and I believe science has a duty to continue
to assemble the building blocks that will be needed to do it".
Archer says that the
technology for recovering degraded DNA and extracting it from museum specimens
is advancing. |
.
| As an adjunct to the
cloning debate, a paper by authors Pask and Renfree from the Department
of Zoology at the University of Melbourne, and Behringer from the University
of Texas was published in the journal "PLoS ONE" (Pask et
al. 2008). The paper, entitled
"Resurrection of DNA Function
In Vivo from an Extinct Genome", described how a fragment of thylacine
DNA had been brought back to life. |
.
A mouse foetus expressing
the thylacine gene, shown by the blue staining.
Source: Andrew Pask and
Richard Behringer.
|
|
In 1999, the researchers obtained
tissue samples from three pouch
pups and the skin of one adult thylacine preserved in ethanol at Museum
Victoria in Melbourne. DNA was subsequently extracted from the tissue
samples. The team then set about isolating small regions of the DNA
that they painstakingly pieced together to provide the sequence of several
genes. One of these was the proa1(II) collagen (Col2a1) gene, which
is involved in making bone.
The team took the "enhancer"
region of this gene and inserted it into the genomes of mouse embryos,
using a genetic delivery method known as a plasmid. They subsequently
showed that the mice were producing the collagen using the thylacine gene
fragment; the first time that DNA from an extinct
species had been used to induce a functional response in another organism.
Many wildlife conservationists
argue that scarce funds used to recreate an extinct species would be better
directed in attempting to preserve critically endangered species, and this
certainly is a valid argument. One could also argue that the advances
made in the attempt to clone the thylacine could, through developments
in reproductive medicine, directly benefit many of these very rare animals. |
. |
| Professor Archer confirmed
in October 2005 that he was assembling a new team to revive the cloning
project. He states: "Public interest in the project is still strong
and researchers from several Australian institutions have expressed interest
in becoming involved. In addition, US researchers with genetic sequencing
capabilities will be involved for the first time and their expertise is
expected to open up new possibilities for bringing the project closer to
its ultimate goal". |
At the time of this
writing, Professor Archer's work on cloning continues at the University
of New South Wales.
There
remains of course a very important and intriguing question which hangs
over all such hope and speculation: is the thylacine actually extinct?
The survival of a relic population of thylacines in the more remote parts
of Tasmania cannot be easily dismissed, as there is sufficient secondary
evidence to infer that the species does indeed still exist. This
in itself does not devalue the significance of thylacine cloning research,
but it does have a bearing on people's perception of the species.
If the thylacine is presumed to be extinct, the resources to try to save
it are diverted elsewhere.
For an in-depth discussion on the history of thylacine sightings, see the
museum's subsections Extinction
vs. Survival and Alleged
Mainland Thylacine Sightings. |
