Nucleotide sequence variation of the major histocompatibility complex class II DQA1 gene in different cattle breeds from Nigeria and New Zealand.

The major histocompatibility complex (MHC) plays a role in immune response. Among other activities, the bovine MHC genes (BoLA) trigger immune responses, including the activation of antibody-producing B-cells. In this study, White Fulani (n = 24), Red Bororo (n = 5) and Holstein-White × Fulani-cross (n = 11) cattle from Nigeria, and New Zealand Holstein-Friesian × Jersey-cross (n = 40) cattle were used to investigate variability in exon 2 of BoLA-DQA1. Ten alleles were identified using a PCR-Single Strand Conformation Polymorphism (SSCP) approach and their nucleotide sequences confirmed by DNA sequencing. A total of 12.60 % of all nucleotide positions analysed were revealed to be variable and two novel BoLA-DQA1 alleles are reported here for the first time.

Identification of novel nucleotide sequence variations in an extended region of the bovine leptin gene (LEP) across a variety of cattle breeds from New Zealand and Nigeria.

Leptin is mainly secreted by white adipose tissue in animals. Leptin acts by stimulating or inhibiting the release of a neurotransmitter, which eventually results in a decrease in food/feed intake and an increase in energy expenditure. In this investigation, the polymerase chain reaction (PCR) coupled with single-strand conformation polymorphism (SSCP) analysis was used to reveal nucleotide sequence variations in bovine leptin gene (LEP) in 338 cattle of a variety of breeds farmed in New Zealand (NZ) and Nigeria. These included NZ Hereford, Angus, Shorthorn, and crossbred Holstein-Friesian  × â€¯Jersey cattle and the Nigerian Sokoto Gudali, Red Bororo, White Fulani, and crossbred Holstein-Friesian  × â€¯White Fulani cattle. Sequence analysis of three regions of bovine LEP that encompassed selected coding and non-coding regions, revealed a total of 12 nucleotide sequence variations (six in exons and six in introns). Of these, three are reported here for the first time, whereas nine have been previously described. Some of the variations identified were common in both the NZ and Nigerian cattle breeds, while others were peculiar to particular breeds from a specific region. The sharing of common variants across different breeds irrespective of geography may indicate an evolutionary relationship, just as the differences within a breed might be attributable to either selective pressure for specific traits or random genetic drift. The detection of both new and previously documented variations in bovine LEP suggests that the gene is highly variable.

Associations between the Bovine Myostatin Gene and Milk Fatty Acid Composition in New Zealand Holstein-Friesian × Jersey-Cross Cows.

The myostatin gene (MSTN), which encodes the protein myostatin, is pleiotropic, and its expression has been associated with both increased and decreased adipogenesis and increased skeletal muscle mass in animals. In this study, the polymerase chain reaction, coupled with single strand conformation polymorphism analysis, was utilized to reveal nucleotide sequence variation in bovine MSTN in 410 New Zealand (NZ) Holstein-Friesian × Jersey (HF × J)-cross cows. These cows ranged from 3 to 9 years of age and over the time studied, produced an average 22.53 ± 2.18 L of milk per day, with an average milk fat content of 4.94 ± 0.17% and average milk protein content of 4.03 ± 0.10%. Analysis of a 406-bp amplicon from the intron 1 region, revealed five nucleotide sequence variants (A-E) that contained seven nucleotide substitutions. Using general linear mixed-effect model analyses the AD genotype was associated with reduced C10:0, C12:0, and C12:1 levels when compared to levels in cows with the AA genotype. These associations in NZ HF × J cross cows are novel, and they suggest that this variation in bovine MSTN could be explored for increasing the amount of milk unsaturated fatty acid and decreasing the amount of saturated fatty acid.

Genetic variations and haplotypic diversity in the Myostatin gene of New Zealand cattle breeds.

Myostatin (MSTN) is a circulating factor that is secreted by muscle cells, and that acts upon those cells to inhibit the proliferation of muscle fibres during pre-natal muscle growth. The Polymerase Chain Reaction (PCR) coupled with Single Strand Conformational Polymorphism (SSCP) analysis, was used to reveal variation in the bovine MSTN gene (MSTN) in 722 cattle from a variety of breeds farmed in New Zealand (NZ). These included Hereford, Angus, Charolais, Simmental, Red Poll, South Devon, Shorthorn, Murray Grey, cross-bred Holstein-Friesian × Jersey cattle, and other composite breeds of cattle. Sequence analysis of five regions of MSTN that encompassed coding and non-coding regions of the gene, revealed a total of twelve single-nucleotide substitutions (7 in intron 1 and 5 in a region spanning the intron 2 - exon 3 boundary), and a single nucleotide deletion. Of these 12 substitutions, five are reported here for the first time, whereas seven have been previously described. The deletion c.748-78del, was located in the intron 2 - exon 3 boundary region, and has been reported previously. No nucleotide variation was identified in exons 1, 2 and 3. A total of 18 extended haplotypes were resolved spanning two variable regions (intron 1 and the intron 2 - exon 3 boundary), some of which were common across the breeds, while others were peculiar to particular breeds. The genetic variations identified provide insight into the conserved and polymorphic nature of the coding and non-coding sequences of bovine MSTN respectively, and thus provides a baseline for further study into how variation in the gene might affect growth and carcass traits in NZ cattle.

Polymorphism in the ovine keratin-associated protein gene KRTAP7-1 and its association with wool characteristics.

The keratin-associated proteins (KAPs) are structural components of wool fibers and variation in the genes encoding the KAPs can affect wool traits. In this study, sequence variation in the ovine KAP7-1 gene (KRTAP7-1) was investigated in 222 sheep across 5 different Pakistani breeds and breed crosses. Two previously identified variants (A and B) of the KRTAP7-1 coding sequence were identified. The frequency of the genotypes AA and AB was 76% and 23%, respectively, and that of BB was 1%. The association of sequence variation with various wool traits and measurements included yield (the proportion of greasy fleece weight that is clean fleece), mean staple length (MSL), wool bulk, mean fiber diameter, fiber diameter SD, the coefficient of variation of fiber diameter, medullation, the SD of medullation, the coefficient of variation of medullation, fiber opacity, the SD of opacity, and the coefficient of variation of opacity. Variation in KRTAP7-1 was found to be associated with yield (P = 0.017). The adjusted mean yield of sheep of genotype AA (n = 169) was 79.9 ±â€…2.72%, while that of genotype AB (n = 51) was 81.9 ±â€…3.37%. There was also an association between variation in KRTAP7-1 and MSL (P = 0.024), with sheep of genotype AA (n = 169) having an adjusted mean MSL of 47.3 ±â€…0.57 mm compared with sheep of genotype AB (n = 51, 50.9 ±â€…0.65 mm). Yield and MSL are both important wool production traits, hence variation in KRTAP7-1 needs to be further investigated in more sheep of differing breed.