A University of Otago researcher is among an international team that has sequenced the sheep genome, pinpointing genes that are unique to sheep, including those that help support secretion of the grease needed to maintain wool.
By comparing its genetic underpinnings to those of other mammals, the researchers identified genes that may explain the sheep's specialised digestive system and the sheep's unique fat metabolism process, which helps maintain its thick, woolly coat.
Dr Jo-Ann Stanton of Otago's Department of Anatomy is a co-author on the paper detailing the genome, which appears in the latest edition of the leading international journal Science. The work was undertaken by the International Sheep Genome Consortium and Dr Stanton and her team worked closely with colleagues from AgResearch on the project.
Dr Stanton says that because sheep are an important agricultural species, the results of this effort will provide crucial resources for future research on this animal.
Sheep are some of the first livestock domesticated by man, cultivated for their meat, milk and wool. These animals have a unique digestive organ, the rumen, which turns plant material into a source of protein, and is found in other ruminants, including sheep, deer and cattle. Beyond nutrition, the team has proposed an absence of expression of a distinctive fatty acid in the skin is linked to wool synthesis.
To explore the genetic foundations of sheep's unusual evolutionary traits, the researchers assembled the reference genome sequences of Texel sheep, a breed originally from the Netherlands.
To clarify the evolutionary relationships among sheep and other mammals based on genetic differences, the researchers constructed a phylogenetic tree that compared standard representative genomes among ruminants and other related species.
The lineage leading to modern day sheep separated from goats and other ruminants, they say, in the late Neogene period, which ended around 2.6 million years ago.
They also uncovered genes that, compared to their homologues in other animals, were expressed differently, and they identified genes that apparently gained new function during rumen evolution.
Their work highlights major genomic signatures associated with interactions between diet, the digestive system and metabolism in ruminants.
For more information, contact:
Dr Jo-Ann Stanton
Senior Research Fellow
Department of Anatomy
University of Otago
Tel 64 3 479 7483
“The sheep genome illuminates biology of the rumen and lipid metabolism” by Y. Jiang at Chinese Academy of Sciences in Kunming, China, and colleagues.
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