February 18, 2010

Scientists Map First 6,000 Year-Old Cattle Genome Sequence

Ancient European aurochs that have been extinct since the 17th century are having their DNA analyzed by scientists, after bone samples were found in a cave in England, BBC News reported.

Mitochondrial DNA, passed down from a mother to her offspring, was confirmed in the DNA analysis of the wild cattle's bone samples. It was the first mitochondrial genome sequence found in an ancient specimen.

The analysis took place at the University College Dublin's Animal Genomics Laboratory and Conway Institute. New technology was used to test the samples, allowing billions of base pairs of DNA to be sequenced. The technology was similar to that used to analyze human hair from a 4,000 year old Greenland specimen recently.

Aurochs DNA was extracted from well-preserved bone discovered in a cave in Derbyshire, England. The bone was dated to the Mesolithic period more than 6,000 years ago. The bone predates farm animals by more than 1,000 years.

Dr Ceiridwen Edwards, who helped with the analysis, said a project was under way to sequence and assemble a complete nuclear genome of the cattle by the end of the year. While mitochondrial DNA copies are quite common in cells, there are only two copies of nuclear DNA -- one from the father and one from the mother -- making it much harder to find.

Previous DNA studies have suggested that modern livestock were descendants from cattle that arrived in Europe from the Neolithic East. However, some aurochs may have been domesticated. If they were domesticated, they were possibly harder than most cattle for the early farmers to manage. "The Near East cattle were smaller and more docile and easier to domesticate. The aurochs were larger and maybe people didn't really want to mess with them," Dr. Edwards theorized.

The species became extinct when the last living female died in a forest in Poland 1627. Many historical figures have been intrigued by the aurochs. Julius Caesar was said to have been impressed by their size. Adolf Hitler wanted to recreate the cattle through selective breeding and use them as a symbol of racial superiority.

Researchers hope to secure funding to reopen the Ancient Biomolecules Centre in Oxford where the work on aurochs genome sequencing could be developed further.

Dr. Edwards had previously attempted to analyze polar bear remains that were thought to be the only remains of that kind in Britain. She had hoped to compare the DNA of the ancient animal with modern polar bears, however, there was not enough DNA left in the sample for an accurate analysis, and her work was never completed.

The remains were thought to be about 18,000 years old. The skull was discovered in 1927 and is kept by the National Museum of Scotland in Edinburgh.


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