We propose an alternative method for casein genotyping, generally
carried out using polymerase chain reaction followed by restriction fragment
length
polymorphism analysis. Application of the single-strand conformation polymorphism
technique detects nucleotide changes in the fragment amplified by means
of
polymerase chain reaction and thus avoids the use of restriction enzymes.
A 453 bp
fragment from exon IV of κ-casein has been amplified. The two
variants (A and B),
found with the highest frequencies in most bovine breeds and included in
some dairy
cattle selection schemes, can be discriminated using single-strand conformation
polymorphism analysis of heat denatured fragments in
acrylamide–bis-acrylamide
(100[ratio ]1) gels followed by silver staining. κ-Casein
genotyping is therefore simplified,
although variants A and E on the one hand, and B and C on the other, are
not
distinguishable with this technique.