Cattle 83 per cent human, or vice-versa?

University of Illinois researchers mapping the cattle genome say that of the genes mapped so far, 83 per cent could be identified as identical to human genes.

“The comparative map has enormous predictive power,” lead researcher Harris Lewin, director of the W.M. Keck Center for Comparative and Functional Genomics at the University of Illinois said in a release.

“For the first time, we can move from a point on the human genome to the equivalent point on the cattle genome. That will allow us to use the map of one species to identify genes controlling important traits in the other, such as those influencing lactation, reproduction and resistance to infectious diseases.”

The comparative map and a second map, providing an up-to-date look at the cattle genome, were published in the September issue of the journal Genome Research.

The releases says a total of 1,087 genetic markers, including 768 known genes, were mapped. About 92 per cent of all cattle chromosomal DNA was included, representing a four-fold increase in the number of previously mapped cattle genes, Lewin said. Among the known genes, 638 (83 per cent) could be identified as identical to human genes that also have positional information on human chromosomes.

The comparative map revealed that up to 149 conserved chromosome segments in humans and cattle, including four whole chromosomes, appear to have the same genes in both species, despite the two species being separated by more than 60 million years of evolution.

Eventually, Lewin said, the cattle genome will be completely sequenced. “In the end” he said, “we will understand the molecular genetic basis for the major phenotypic differences among the mammals. This will have enormous scientific and practical significance.

“Breeding cattle for resistance to infectious diseases, for instance, would reduce our dependence on antibiotics in feed, a major concern for human health and food safety,” he said.

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