DNA-based identification of novel bovine casein gene variants

Abstract

In cattle, at least 39 variants of the 4 casein proteins (α(S1)-, β-, α(S2)- and κ-casein) have been described to date. Many of these variants are known to affect milk-production traits, cheese-processing properties, and the nutritive value of milk. They also provide valuable information for phylogenetic studies. So far, the majority of studies exploring the genetic variability of bovine caseins considered European taurine cattle breeds and were carried out at the protein level by electrophoretic techniques. This only allows the identification of variants that, due to amino acid exchanges, differ in their electric charge, molecular weight, or isoelectric point. In this study, the open reading frames of the casein genes CSN1S1, CSN2, CSN1S2, and CSN3 of 356 animals belonging to 14 taurine and 3 indicine cattle breeds were sequenced. With this approach, we identified 23 alleles, including 5 new DNA sequence variants, with a predicted effect on the protein sequence. The new variants were only found in indicine breeds and in one local Iranian breed, which has been phenotypically classified as a taurine breed. A multidimensional scaling approach based on available SNP chip data, however, revealed an admixture of taurine and indicine populations in this breed as well as in the local Iranian breed Golpayegani. Specific indicine casein alleles were also identified in a few European taurine breeds, indicating the introgression of indicine breeds into these populations. This study shows the existence of substantial undiscovered genetic variability of bovine casein loci, especially in indicine cattle breeds. The identification of new variants is a valuable tool for phylogenetic studies and investigations into the evolution of the milk protein genes.

Effects of different genotypes at the CSN3 and LGB loci on milk and cheese-making characteristics of the bovine Cinisara breed

“…The description of the first milk protein polymorphism can be traced back to 1955, when Aschaffenburg and Drewry (1955) discovered the two most frequent b-lactoglobulin (LGB) alleles, A and B. At present, 11 alleles are known at this locus (Caroli, Chessa, & Erhardt, 2009;Farrell et al, 2004;Gallinat et al, 2013), which is located on chromosome BTA11 (Hayes & Petit, 1993). Later studies showed that LGB alleles greatly influence the b-lactoglobulin content of milk, with a reduced synthesis for cows with the LGB B allele compared with LGB A allele of about 25%.…”

Generation and identification of anti‐inflammatory peptides from bovine β‐casein using enzyme preparations from cod and hog

“…The β‐casein fragments exhibit masses ranging from about 640 to 7500 Da (MH + ) and retention times from 2.5 to 33 min. Because commercially available rennet casein was used for isolation of β‐casein, peptide sequences of the genetic variants of β‐casein A 1 (peptides 17(1–3)), A 2 (peptides 13, 19(1–3)) and B (peptide 9) were found. The identified peptides of hydrolysates generated with the enzyme preparations cod trypsin and porcine trypsin (TPCK), which contain only tryptic activity, are very similar.…”

Bos indicusintrogression into (peri-)alpine cattle breeds - evidence from the analysis of bovine whey protein variants

“…In Sarabi and Golpayegani cattle, LAA*B occurred at frequencies of about 0.7, possibly reflecting a various degree of admixture between taurine and indicine breeds, which has previously been shown on a genome‐wide scale (Gallinat et al . ). Variant LAA*A was present in all indicine and admixed breeds with the highest frequency of 0.25 in Gir, whereas it was found in only one taurine breed at a very low frequency (Table ).…”

“…The entire open reading frames of LALBA (474 animals) and LGB (316 animals) were sequenced as described by Gallinat et al . (; primer sequences given in Table S1).…”