The cow genome has been sequenced
Two large international consortium scientists with a total of 300 people from 25 countries have completed a project to read the complete genome of one domestic cow and study the genetic variation of different breeds of cows. Scientists led by Richard Gibbs from Baylor College of Medicine in Houston, USA, presented their results in two articles published in the latest issue of Science.
The first paper describes the results of the work on reading the complete genome of the cow L1 Dominette 01449 of the famous Hereford breed selected for sequencing. The project took 6 years of scientists' work and cost $53 million. Scientists estimate the number of genes encoded by about 2.87 billion pairs of nucleotides in cow DNA at 22 thousand – slightly more than in humans. Of these, 13 thousand have analogues in the genomes of seven other mammals, with the decoded genome – human, dog, mouse, rat, possum and platypus; if we exclude the last two from consideration, there will be more than 14 thousand orthologs.
The second paper describes the results of a side project that cost a hundred times less – comparing the genome of almost 500 cows of 19 different breeds by 37,740 markers – single nucleotide polymorphisms ("snips"). Analysis of these data shows a recent (on the time scales of millennia) significant decrease in the genetic diversity of the species Bos taurus. The authors are almost sure that the reason for this is the domestication of a small (relatively wild population) number of cows by humans. At the same time, although genetic diversity is reduced, it is at a quite decent level that does not threaten the survival of the species – about the same as in humans.
Breeders hope that the new information will allow them to more confidently choose individuals for crossing and purposefully breed new breeds: the average cost of haplotyping a cow for 37 thousand markers is only about $ 1,000 against the tens of thousands needed to conceive and grow a thoroughbred cow for breeding purposes. Scientists are confident that the new data will help to breed new meat and dairy breeds with the right characteristics and fight various diseases of livestock.
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