Lewin calls the breakpoint regions “hotspots of evolution in the genome.”
Another analysis led by Lewin, a study of metabolic genes performed by Seongwon Seo, a postdoctoral fellow in Lewin's lab and now a professor at Chungnam National University in South Korea, found that five of the 1,032 genes devoted to metabolic functions in humans are missing from the cattle genome or have radically diverged. This suggests that cattle have some unique metabolic pathways.
These differences in metabolism, along with changes in genes devoted to reproduction, lactation and immunity are a big part of what makes a cow a cow.
For example, one of the changed genes, histatherin, produces a protein in cow's milk that has anti-microbial properties. The researchers also found multiple copies of a gene for an important milk protein, casein, in a breakpoint region of one of the chromosomes.
“Having the genome sequence is now the window to understanding how these changes occurred, how ruminants ended up with four stomachs instead of one, how the cow's immune system operates and how it is able to secrete large amounts of protein in its milk,” Lewin says.
The sequencing project and analysis was coordinated by Richard Gibbs and George Weinstock, of the Baylor College of Medicine; Chris Elsik, of Georgetown University; and Ross Tellam, of the Commonwealth Scientific and Industrial Research Organization of Australia (CSIRO). University of Illinois animal sciences professor Lawrence Schook was on the team that wrote the sequencing project white paper, which was instrumental in securing funding for the initiative.
Source: University of Illinois