An allele associated with a non-detectable amount of αs2 casein in goat milk

✍ Scribed by L. Ramunno; E. Longobardi; M. Pappalardo; A. Rando; P. Di Gregorio; G. Cosenza; P. Mariani; N. Pastore; P. Masina

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 285 KB
• Volume: 32
• Category: Article
• ISSN: 0268-9146
• DOI: 10.1046/j.1365-2052.2001.00710.x

✦ Synopsis

The goat CSN1S2 locus is characterized by the presence of three alleles, A, B and C, all associated with about 2.5 g/l of protein per allele. The SDS–PAGE analysis of 441 individual milk samples obtained from goats belonging to a population reared in Southern Italy showed that the milk produced by three goats did not apparently contain __α__s~2~‐casein, whereas milk produced by 37 goats showed a less intense electrophoretic band of this casein fraction (about 50%). These results can be explained by hypothesizing the presence of another allele at this locus, CSN1S2^0^, associated with a ‘null’ content of __α__s~2~‐casein. Southern blot, PCR and PCR–RFLP analyses of the DNA region containing the CSN1S2 gene of individuals producing milk with and without __α__s~2~‐casein did not show differences between the two groups. As a consequence, goats producing milk without __α__s~2~‐casein carry an apparently intact gene. The first results obtained by sequencing part of the CSN1S2^0^ allele revealed a G→A transition at nucleotide 80 of the 11th exon which creates a stop codon and could be responsible for the absence of the __α__s~2~‐casein in goat milk. This mutation eliminates a __Nco__I restriction site. A test based on this polymorphism has been established in order to identify carriers of the CSN1S2^0^ allele.