Molecular Characterisation of κ-Casein Gene in Girgentana Dairy Goat Breed and Identification of Two New Alleles

• Published in: Italian journal of animal science Vol. 14; no. 2; p. 3464
• Main Authors: Di Gerlando, Rosalia, Tortorici, Lina, Sardina, Maria T., Monteleone, Giuseppina, Mastrangelo, Salvatore, Portolano, Baldassare
• Format: Journal Article
• Language: English
• Published: Bologna Taylor & Francis 01.01.2015; Taylor & Francis Ltd
• Subjects: Alleles; Amino acids; Casein; CSN3 gene; Genetic diversity; Girgentana goat breed; New alleles; Polymorphisms; Single-nucleotide polymorphism
• ISSN: 1828-051X; 1594-4077; 1828-051X
• DOI: 10.4081/ijas.2015.3464

The κ-casein fraction plays an important role in the formation, stabilisation and aggregation on casein micelles and thus affects technological and nutritional properties of milk. In this study, exon 4 of κ-casein (CSN3) gene was sequenced and analysed in Girgentana goat breed. Analyses of the obtained sequences showed the presence of A, B, D, and G known alleles and two new genetic variants, named D' and N. The new D' allele differs from D in one transition, G 284 →A 284 , which did not cause amino acid change. The new N allele differs from A in five single nucleotide polymorphisms (SNPs): T 245 /C 245 , G284/A284, G309/A309, G471/A471 and T591/C591, while it differs from C in one transition, i.e. T 583 →C 583 . Comparing the amino acid sequences of N and A alleles, the first two SNPs caused no amino acid change, whereas the other SNPs produced changes (Val 65 /Ile 65 , Val 119 /Ile 119 , and Ser 159 /Pro 159 , respectively). Comparison of N allele with C revealed the amino acid change Val 156 →Ala 156 . The most frequent allele was A (0.480) followed by B (0.363), D (0.112), and N (0.034). The D' and G alleles were identified only in two animals and in heterozygous conditions with a very low frequency (0.005). The most common genotype was AB (39.5%) followed by AA (19.5%), AD (12.7%), and BB (11.7%). Homozygous D'D', GG, and NN individuals were not found. Further analysis will be performed in order to establish associations among genotypes and quantitative and qualitative milk traits.