Abstract for presentation at 11th International Congress of Human Genetics

The availability of the draft bovine genome provides the opportunity to further our knowledge of the adaptive evolution of the ruminant life style. In the present study we describe the complete Bactericidal/Permeability Increasing (BPI)-like locus on BTA13 and report the expansion of the BSP30 proteins, the bovine homolog of human Paratoid Secretory Protein locus (PSP). Four fully functional BSP30 genes remain in cattle, derived from eight genomic duplications which have taken place during the ruminant evolution. These four BSP30 proteins show marked evidence of positive selection. This is likely a consequence adaptation of their alimentary tract to digest cellulose. Plant material is digested in the novel compartment, the rumen, which has a markedly altered pH compared to the stomach, and consists of a milieu containing a high density of anaerobic bacteria as compared to the acid and nearly sterile environment in monogastrics. The functional reason for the retention of the gene duplication mutations remains to be elucidated, but the multiple variants presumably allow more precise control as young ruminants change from a mono-gastric (milk fed) to ruminant (grass-fed) diet and subsequent variations in the roughage consumed. This gene family is part of a much larger gene cluster that has undergone multiple rounds of duplication prior to mammalian radiation and has a role in innate immunity of mucosal surfaces.