Polymorphism of αS1-casein in goat milk: identification of A, B, E and F variants by biochemical and genetic analysis

Many researches, related to genetic polymorphism of αS1-casein in goat milk, showed a marked variability and implications in milk and dairy product traits. The genetic variants (from A to G) were associated with four levels of expression: 3,6 g/L per A, B and C (“strong” alleles); 1,6 g/L per E (“medium” allele); 0,6 g/L per F (“weak” allele) and 0 g/L per O (“null” allele). Differences existing among the A, B, C, D, E, F, G and O have been described (Grosclaudeet al., 1994). To analyze genetic polymorphism of caseins from goat milk, distinct electrophoretic (Russoet al., 1986; Addeoet al., 1988) and chromatographic techniques (Jaubert and Martin, 1992; Iamettiet al., 1999) were applied. In last years, the advancement in technological field is allowing the research of primary structure of protein variants (Ferrantiet al., 1997; Trujilloet al., 2000) and basic sequence of new alleles (Martinet al., 1999; Bevilacquaet al., 2002; Ramunnoet al., 2002). In this work, we employed electrophoretic protein separation (IEF and SDS-PAGE), chromatographic analysis (RP-HPLC) and molecular biology techniques based on polymerase chain reaction (real-time PCR) to detect αS1-CN genetic variants from goat milk. The utility of protein and DNA analysis combination was discussed.