CHARACTERIZATION OF THE CSN1A(G) ALLELE OF THE BOVINE ALPHA-S1-CASEINLOCUS BY THE INSERTION OF A RELICT OF A LONG INTERSPERSED ELEMENT

The bovine CSN1A(G) allele is associated with a lower proportion of al pha(s1)-casein in milk and is characterized by an insertion in the las t noncoding exon (19th). According to DNA sequence analysis, the locat ion, length, and origin of the insertion characterizing the bovine CSN 1A(G) allele have been identified. This insertion interrupts the 19th exon between nucleotides 58 and 59, is 371 bp long, and has a high lev el of homology with relicts of long interspersed elements of retroposi tional origin. Northern blot analysis shows that the inserted element is transcribed and that the number of transcripts of the CSN1A(G) alle le is less than one-half of the number of transcripts of the CSN1A(B) allele. The lower amount of alpha(s1)-casein in milk obtained from cow s carrying the CSN1A(G) allele can be explained by a reduced mRNA stab ility. Furthermore, a method has been developed using polymerase chain reaction for identification of the carriers of the CSN1A(G) allele.