Molecular Characterisation ofκ–CaseinGene inGirgentanaDairy Goat Breed and Identification of Two New Alleles

Abstract

The k-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 k-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, G284→A284, which did not cause amino acid change. The new N allele differs from A in five single nucleotide polymorphisms (SNPs): T245/C245, G284/A284, G309/A309, G471/A471 and T591/C591, while it differs from C in one transition, i.e. T583→C583. 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 (Val65/Ile65, Val119/Ile119, and Ser159/Pro159, respectively). Comparison of N allele with C revealed the amino acid change Val156→Ala156. 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.

Population genetic structure and milk production traits in Girgentana goat breed

“…In a previous study Gigli et al (2008) reported A-C-A-B as the most frequent in Girgentana goat. These results may be explained considering the different allele frequency at CSN3*A reported by Di Gerlando et al (2015) (0.480) compared with those reported in the previous study by Gigli et al (2008) (0.127). In fact, the flocks are not the same of Gigli et al (2008) and number of animals within flocks has changed during these past years, and then, the individual analysed samples are not the same of previous work.…”

“…Molecular data of casein (CAS) gene polymorphisms for Girgentana breed from our previous studies on CSN1S1 (Mastrangelo et al 2013a), CSN2 (Tortorici et al 2014), CSN1S2 (Palmeri et al 2014), and CSN3 (Di Gerlando et al 2015), were used to infer haplotypes. Haplotypes distributions were analysed using HAPLOTYPE procedures of SAS (SAS Institute Inc.).…”

“…Moreover, different genotyping protocols were used. In fact, the CSN3 gene was genotyped using the Sanger sequencing protocol by Di Gerlando et al (2015), whereas Gigli et al (2008) used the PCR-single-strand conformation polymorphism protocol. The second most frequent haplotype was F-C1-F-B (18.2%) recently reported in two Italian local goat breeds but with lower frequencies (Martini et al 2010;Cornale et al 2014).…”

Quantitative determination of casein genetic variants in goat milk: Application in Girgentana dairy goat breed

“…e For computation of the number of theoretical plates, peak width at the baseline was obtained by tangential lines drawn at half-height. However, the casein genetic variants quantified in our study were the most frequent in Girgentana goat breed; in fact, at CSN1S2, the most frequent alleles were A and F (Palmeri, Mastrangelo, Sardina, & Portolano, 2014), at CSN2 were C and C1 (Tortorici, Di Gerlando, Mastrangelo, Sardina, & Portolano, 2014), and at CSN3 gene were A and B (Di Gerlando et al, 2015). Comparing our data with those reported by Bonanno et al (2013), which used a different chromatographic method, it can be possible to state that our applied chromatographic conditions allowed in less time running, run was 5 min shorter, a greater separation and resolution of caseins as higher distance between caseins peaks.…”

The Girgentana Goat Breed: A Zootechnical Overview on Genetics, Nutrition and Dairy Production Aspects

“…Tortorici et al (2014) showed the presence of C, C1 and A strong alleles, and 0' null allele at CSN2 gene, whereas the most common genotypes are CC1 followed by CC, C1C1 and C0′. The exon 4 of CSN3 gene was sequenced and analysed by Di Gerlando et al (2015). 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 most common genotype is AB followed by AA, AD and BB.…”