title: Sequence variation of the alpha-lactalbumin gene in Holstein and Nellore cows.
abstract: The alpha-lactalbumin is a subunit of lactose-synthase, an enzyme responsible for lactose production, a disaccharide that influences milk production. Sequence variations of bovine alpha -lactalbumin have been associated with differences in milk yield. This study aimed to analyze allelic frequency differences at position - 1689 (g. A > G) and + 15 (g. A > G) of the alpha-lactalbumin gene in Holstein (Bos taurus) and Nellore (Bos indicus) cows. Blood samples were analyzed from 34 Holstein, 104 Nellore, and 99 Dairy Nellore cows using PCR-RFLP. The different RFLP patterns were sequenced and a novel sequence variation on nucleotide - 46 was identified. An adenine at this position was designated as the A allele and a guanine was designated B allele. The frequencies of alleles A - 1689, A - 46, and A + 15 differed between Holstein and both Nellore breeds. The results show that differences in alpha-lactalbumin allelic variants in the 5'-flanking and the 5'-UTR region might be associated with differences in milk production between Holstein cows and cows from Nellore breeds. However, the lack of difference between Nellore and Dairy Nellore suggests that other sequence variantions that regulate milk production might be responsible for the selection of Dairy Nellore cows with superior milk production.
authors.affiliation: Department of Animal Reproduction, Faculty of Veterinary Medicine, University of Sao Paulo, Rua Orlando Marques de Paiva, Sao Paulo-SP/Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Martins
authors.forename: M P
authors.initials: MP
authors.lastname: Milazzotto
authors.forename: W B
authors.initials: WB
authors.lastname: Feitosa
authors.forename: A R S
authors.initials: AR
authors.lastname: Coutinho
authors.forename: R
authors.initials: R
authors.lastname: Simoes
authors.forename: M G
authors.initials: MG
authors.lastname: Marques
authors.forename: M E O A
authors.initials: ME
authors.lastname: Assumpcao
authors.forename: J A
authors.initials: JA
authors.lastname: Visintin
mesh_terms: D024506:5' Flanking Region / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D002417:Cattle / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D007768:Lactalbumin / Q000235:genetics*; D007774:Lactation / Q000235:genetics; D008892:Milk; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA
chemical_list: D020121:5' Untranslated Regions; D004247:DNA; D007768:Lactalbumin