title: Short communication: CSN1S1-CSN3 (α(S1)-κ-casein) composite genotypes affect detailed milk protein composition of Mediterranean water buffalo.
abstract: The aim of the study was to investigate the effect of composite CSN1S1-CSN3 [α(S1)-κ-casein (CN)] genotype on milk protein composition in Mediterranean water buffalo. Content of α(S1)-CN, α(S2)-CN, β-CN, γ-CN, κ-CN, glycosylated and unglycosylated κ-CN, α-lactalbumin, and β-lactoglobulin was measured by reversed-phase HPLC using 621 individual milk samples. Genotypes at CSN1S1 and CSN3 were also obtained by reversed-phase HPLC. Two alleles were detected at CSN1S1 (corresponding to the A and B variants, O62823: p.Leu193Ser,) and at CSN3 (corresponding to the X1 and X2 variants, CAP12622.1: p.Ile156Thr). Increased proportions of α(S1)-CN in total casein (TCN) were associated with genotypes carrying CSN1S1 A. Genotypes associated with a marked decrease of the proportion of α(S1)-CN in TCN (composite genotypes AB-X1X1 and BB-X1X2) were associated with marked increases in the proportion of α(S2)-CN. In addition, composite genotypes carrying the X1 allele at CSN3 were associated with a greater proportion of α(S2)-CN in TCN relative to those carrying CSN3 X2. Composite genotypes greatly affected also the variability of ratios of κ-CN to TCN, with genotypes carrying the X1 allele at CSN3 being associated with decreased ratios. The decreased content of glycosylated κ-CN associated with CSN3 X1 was responsible for the overall lower content of total κ-CN in milk of X1-carrying animals. Increasing the frequency of specific genotypes might be an effective way to alter milk protein composition, namely the proportion of α(S1)-CN, α(S2)-CN, and κ-CN in TCN, and the degree of glycosylation of κ-CN.
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro Padova, Italy. valentina.bonfatti@unipd.it
authors.forename: V
authors.initials: V
authors.lastname: Bonfatti
authors.forename: M
authors.initials: M
authors.lastname: Giantin
authors.forename: M
authors.initials: M
authors.lastname: Gervaso
authors.forename: R
authors.initials: R
authors.lastname: Rostellato
authors.forename: A
authors.initials: A
authors.lastname: Coletta
authors.forename: M
authors.initials: M
authors.lastname: Dacasto
authors.forename: P
authors.initials: P
authors.lastname: Carnier
mesh_terms: D000483:Alleles; D000818:Animals; D002020:Buffaloes / Q000235:genetics*; D002364:Caseins / Q000032:analysis / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D056148:Chromatography, Reverse-Phase / Q000662:veterinary; D005260:Female; D005838:Genotype; D007768:Lactalbumin / Q000032:analysis / Q000235:genetics; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000235:genetics*
chemical_list: D002364:Caseins; D008894:Milk Proteins; D007768:Lactalbumin