The ‘virtual sheep genome’ – a physical DNA map of more than 98 per cent of the sheep genome – will be made publicly available by CSIRO this week.  It contains the ‘best bet’ about where the sheep’s vast amount of hereditary information can be found on its 26 chromosomes.

The new sheep genome data will now fast-track the identification of the crucial genes responsible for sheep health and productivity, as well as for wool and meat quality.  It is set to speed up the development of DNA marker tests, which will allow sheep breeders to identify and select animals with superior muscle quality and quantity, parasite resistance and wool quality.

A bioinformatics scientist from CSIRO Livestock Industries in Brisbane who leads the research, Dr Brian Dalrymple, said his team drew on major components of the $3 billion investment in the human genome and also work already done on the genomes of the dog and cow (CSIRO was a partner in the US$53 million Bovine Genome Sequencing Project).

“Internationally there has been substantial genomics research undertaken on cattle, with a near complete cow genome sequence now publicly available,” Dr Dalrymple said.

“While the investment in sequencing the sheep genome will eventually be made, we have been very pragmatic and resourceful in the meantime.  We have worked out how to leverage the investment in the other mammalian genomes to build a virtual genome around the small amount of existing sheep sequence,” he said.

“Our research has laid the ground work for the eventual sequencing of the sheep genome itself.” 

Dr Dalrymple’s scientific team drew on the fact that the genes for sheep are similar to the genes for humans – the major difference being their order on the chromosomes.

“We took the DNA sequences from the ends of 180,000 sheep DNA fragments called BACs (Bacterial Artificial Chromosomes – chromosomes that have been stored in bacteria) which covered the sheep genome about 12 times over,” he said.

“Then it was like a giant puzzle.  We mapped the BAC-end sequences onto the frameworks of the human, dog and cow genomes.  That honed the information down to 1,172 sections of sheep genome, which we had to put together in the right order with the right orientation.”

The virtual sheep genome has been made possible by SheepGenomics, a major, joint research initiative of Meat and Livestock Australia and Australian Wool Innovation, which is supported by 11 research organisations in both Australia and New Zealand.  This work is part of the development of a range of sheep genomics resources by the International Sheep Genomics Consortium, a partnership of scientists and funding agencies from Australia, France, Kenya, NZ, the UK and US.