Polymorphisme génétique des protéines du lait dans des populations de taurins et de zébus africains. Caractérisation des variants alpha s1-Cn H et kapa-Cn J (Bos taurus, Bos indicus)

• Published in: Genetics selection evolution (Paris) 1999, Vol.31 (3), p.239-253
• Main Authors: Mahe, M Francois, Miranda, Guy, Queval, R., Bado, Andre, Souvenir Zafindrajaona, P.S., Grosclaude, F.
• Format: Article
• Language: fre
• Subjects: Genetics; Life Sciences
• ISSN: 0999-193X; 1297-9686

The polymorphism of caseins, α-lactalbumin and ß-lactoglobulin was investigated in African Bos taurus (N’Dama, Baoulé, Kuri) and Bos indicus (Shuwa Arab, Sudanese Fulani) populations. The respective frequencies of alleles αs1-CnB and αs1-CnC in the N’Dama (0.89 and 0.11) and Baoulé (0.92 and 0.08) breeds were almost opposite to those found in the Shuwa Arab zebu (0.22 and 0.78), a true zebu, which confirms a phenomenon already documented in the literature. Because the αs1-CnB, ß-CnA1, К-CnB haplotype was strongly predominant in N’Dama and Baoulé (0.56 and 0.60), as compared to the αs1-CnC, ß-CnA2, К-CnA haplotype in the Shuwa Arab zebu (0.63), an opposite trend in frequencies was also observed between taurines and zebus at the ß-Cn and К-Cn loci. These results confirm that the polymorphism of caseins provides an efficient marker system to discriminate Bos taurus from Bos indicus origins. The Kuri was at an intermediate position, since, in this population, the αs1-CnB allele predominated as in taurines, while the αs1-CnC, ß-CnA2, К-CnA. The polymorphism of caseins, α-lactalbumin and ß-lactoglobulin was investigated in African Bos taurus (N’Dama, Baoulé, Kuri) and Bos indicus (Shuwa Arab, Sudanese Fulani) populations. The respective frequencies of alleles αs1-CnB and αs1-CnC in the N’Dama (0.89 and 0.11) and Baoulé (0.92 and 0.08) breeds were almost opposite to those found in the Shuwa Arab zebu (0.22 and 0.78), a true zebu, which confirms a phenomenon already documented in the literature. Because the αs1-CnB, ß-CnA1, К-CnB haplotype was strongly predominant in N’Dama and Baoulé (0.56 and 0.60), as compared to the αs1-CnC, ß-CnA2, К-CnA haplotype was the most frequent, as in zebus. This may be interpreted as revealing intercrossings with zebus in the previous history of this cattle type. Conversely, but to a lesser degree, the polymorphism of the Sudanese Fulani zebu indicates a taurine influence, in accordance with what is accepted about the origins of this cattle type. No polymorphism of αs2-casein could be identified, while α-lactalbumin was polymorphic in all populations. Two additional variants, probably specific to African cattle, were observed. Variant H of αs1-casein, found in kuri, is characterized by the deletion of the eight amino acid residues (51-58) coded by exon 8, a probable consequence of exon skipping. Allele αs1-CnH is derived from αs1-CnB. Variant J of К-casein, found in Baoulé, is derived from variant B by the substitution of Ser 155 (B)