Analysis of polymorphism in the bovine casein genes by use of the polymerase chain reaction

Genotyping of κ-casein and β-lactoglobulin genes in native cattle from Barishal region of Bangladesh

The study was conducted to determine the genetic variants of κ-casein and β-lactoglobulin genes in native cattle. DNA was extracted from blood samples (n = 80) collected from Babuganj, Barishal followed by PCR with gene-specific primers. Genotyping was done by RFLP with HindIII, and HaeIII restriction enzymes. Allelic and genotypic frequencies, genetic diversity, heterozygosity and Hardy-Weinberg equilibrium were estimated using the Popgen32 software. A total 80 samples were genotyped and three genotypes, namely AA, AB and BB, were detected for both the genes. In case of κ-casein gene, higher frequency was observed for AA genotype (0.73) followed by AB (0.23) and BB (0.04) genotype. A allele (0.84) was found to dominate over B allele (0.16). For β-lactoglobulin gene, BB genotype (0.66) was found more frequently than AB (0.18) and AA (0.16) genotypes. Highest frequency was found for B (0.75) followed by A (0.25) allele. The average genetic diversity (He) was 0.38. The result indicated differences between observed (Ho) and expected (He) heterozygosity and it was out of equilibrium genetics, assumed that selection pressure was in population. To the best of our knowledge, this is the first reported study on κ-casein and β-lactoglobulin gene variants analysis in cattle in Bangladesh.

Revisión: E1 polimorfismo del gen de la caseina αs1 caprina y su efecto sobre la producción, la composición y las propiedades tecnológicas de la leche y sobre la fabricación y la maduración del queso

The caprine α s1-casein gene displays a high degree of polymorphism, with eight different protein variants described up to date. The rate of synthesis of the mature protein is closely linked to the caprine αs1-casein genotype. There are three variants which are associated to high αs1-casein content in milk (A, B, and C), one to an intermediate content (E), three to a low content (D, F, and G) and one to a null content (O). During the last few years studies of goat milk protein polymorphism have gained renewed interest, as the ocurrence of certain milk protein genetic variants is correlated with the composititon of milk and also with some milk processing parameters. For instance, analyses of the physicochemical properties of milk from goats homozy gous for the three main α s1-casein alleles (A, E, F) confirm the effects of the genotypes on the percentage of casein and fat, and shows significant effects on the diameter of the micelles and their calcium content. These characteristics seem to be associated with enhanced clotting of goat milk, cheese curd firmness, curd syneresis and overall cheese yield. The caprine αs1-casein gene constitutes a very attractive model for studying the regulation of the expression of the corresponding protein, and might also become a very powerful tool in improving the technolog ical properties of goat milk.

Caracterização de rebanhos leiteiros da raça Girolando através da tipificação de marcadores moleculares para kappa-caseína

<p>Objetivou-se caracterizar o genótipo da kappa-caseína em 144 vacas Girolando, do Estado de Pernambuco, utilizando a técnica de PCR-RFLP. Foram coletadas amostras de sangue total desses animais dos seguintes grupos genéticos: 30 ½ holando-gir, 38 ¾ holando-gir e 76 ⅝ holando-gir. Desse material foi extraído o DNA. Através do DNA foi determinada uma região que foi amplificada e seu produto sofreu ação da enzima de restrição HindIII para observar os possíveis polimorfismos. Foram encontrados os seguintes genótipos com respectivas frequências: AA (0,59); AB (0,25) BB (0,06); AC (0,05); BC (0,02) e CC (0,02). As frequências alélicas observadas para os genes A, B e C foram 0,74; 0,20 e 0,06, respectivamente. Há de se registrar a detecção do gene C na população, raramente descrito em outros trabalhos. A presença do genótipo BB na população de vacas holando-gir aponta para implantação de programas de seleção genética visando aumento na frequência do genótipo em questão, o que possibilitará ganhos significativos na cadeia do leite, particularmente, para produtores e indústrias de processamento.</p>

Investigating the genetic polymorphism of sheep milk proteins: a useful tool for dairy production

Sheep is the second most important dairy species after cow worldwide, and especially in the Mediterranean and Middle East regions. In some countries, the difficult environmental conditions require a peculiar adaptation and, in these contexts, sheep are able to provide higher quality protein than cattle. In the least-developed countries, the amount of dairy sheep and ovine milk production is progressively increasing. In order to improve dairy productions, in particular those with local connotations, it is necessary to obtain in-depth information regarding milk quality and rheological properties. The genetic polymorphisms of milk proteins are often associated with quantitative and qualitative parameters in milk and are potential candidate markers that should be included in breeding strategies similar to those already available for cattle. Due to the current and growing interest in this topic and considering the large amount of new information, the aim of this study was to review the literature on sheep milk protein polymorphisms with a particular emphasis on recent findings in order to give scientists useful support. Moreover, the effects of different protein variants on milk yield and composition are discussed.

Identification of a null allele in genetic tests for bovine leukocyte adhesion deficiency in Pakistani Bos indicus × Bos taurus cattle

Two clinically healthy mature Pakistani Bos indicus × Bos taurus cattle were genotyped as homozygous affected for the lethal immunodeficiency disorder bovine leukocyte adhesion deficiency (BLAD) using previously described PCR-RFLP based DNA tests which was confirmed by sequencing. Sequencing of Bos taurus and B. indicus × B. taurus genomic DNA surrounding the disease causing mutation (c.383A > G) in the ITGB2 gene identified numerous variations in exonic and intronic regions within and between species, including substantial variation in primer annealing sites for three PCR-RFLP tests for one of the B. indicus allelic variants. These variations in the primer annealing sites resulted in a null allele in the DNA tests causing the misdiagnosis of some heterozygous B. taurus × B. indicus cattle to be classified as homozygous affected. New primers were designed and a modified test was developed which simultaneously identified the disease mutation and the Pakistani B. indicus allelic variant associated with the null allele in the previous test.

Detection of bovine αs1-casein genomic variants using the allele-specific polymerase chain reaction

A method was developed to distinguish between genotypic variants B and C of bovine alpha s1-casein, using the allele-specific polymerase chain reaction (ASPCR). The alpha s1-casein genotype determined for 17 Jersey cows by the ASPCR method was confirmed by typing the alpha s1-casein milk proteins on isoelectric focusing gels. Using the ASPCR method described, rapid analysis of the alpha s1-casein genotype of bulls is now possible. In addition, kappa-casein genotypes can be determined from the same PCR reaction.

Direct sequencing and bidirectional allele specific polymerase chain reaction of the bovine beta-casein B variant

We have used the polymerase chain reaction (PCR) to amplify exon VII of the bovine beta-casein gene. The mutations responsible for the B variant were identified by direct sequencing of the amplification products. A bidirectional allele-specific PCR method (BAS-PCR) has been developed using oligonucleotides overlapping the mutation site at their 3' ends. This new procedure allows a rapid and reliable discrimination between the B and non-B alleles of beta-casein.

Análise de polimorfismos do gene da kapa-caseína em fêmeas da raça Nelore e efeito sobre o peso à desmama de suas progênies

Informações sobre peso à desmama de um rebanho Nelore, após ajuste para idade padrão de 205 dias, sexo da cria, idade da mãe, touro e mês de desmama, foram utilizadas para separar as reprodutrizes em dois grupos, cujos produtos diferiam em peso. As médias ajustadas pelo método dos quadrados mínimos e erros-padrão para os grupos pesado (P) e leve (L) foram 163,21±2,18kg e 134,44±2,18kg, respectivamente, com 41 animais em cada grupo. Colheram-se amostras de sangue das reprodutrizes para o estudo de polimorfismos do gene da kapa-caseína, pela técnica de polymerase chain reaction-restriction fragment length polymorphism. A análise de um segmento do éxon IV do gene da kapa-caseína identificou os genótipos 71AA, 10AB e 1BB, com as freqüências de 0,92 e 0,08 para os alelos A e B, respectivamente. Os pesos à desmama dos produtos dos genótipos AA e AB foram, respectivamente, 147,73±2,38kg e 156,76±6,35kg. Os grupos P e L não diferiram entre si quanto às freqüências alélicas apresentadas para esse gene. O genótipo das reprodutrizes não afetou o peso à desmama de suas crias, existindo, portanto, outros efeitos genéticos e não genéticos de maior magnitude.

Kappa-casein polymorphisms in Indian dairy cattle and buffalo: a new genetic variant in buffalo

We screened 57 Sahiwal cattle (Bos indicus) and 53 Murrah, 19 Nili-Ravi and 11 Egyptian buffaloes (Bubalus bubalis) to detect the polymorphisms at kappa-casein (CSN3) gene using the polymerase chain reaction (PCR). CSN3 A and B alleles were identified by PCR-RFLP using the restriction enzymes that detect the underlying nucleotide changes at codon 136 (Taql) and at codon 148 (HindIII or HinfI) in cattle. The frequency of CSN3 B allele in the Sahiwal cattle was estimated as 0.16 with no homozygous BB animal. Using the same set of primers as used in the Sahiwal cattle, a part of exon IV of buffalo CSN3 gene was amplified, but restriction enzyme analysis using HindIII/HinfI and TaqI did not reveal any polymorphism. However, DNA sequencing of the amplified fragment (GenBank Acc. No. U96662) revealed one polymorphism at codon 135 (ThrACC -->I1eATC) in buffalo; the frequencies of 135 Thr/Ile alleles were estimated as 0.88 and 0.12, respectively.

Factors influencing adherence of Streptococcus dysgalactiae to bovine mammary epithelial cell monolayers

Factors that affected adherence of Streptococcus dysgalactiae to monolayers of primary bovine mammary epithelial cells and to a bovine mammary epithelial transformed cell line were evaluated. Cell culture medium inhibited more than 99% of binding of S. dysgalactiae to plastic and was as effective as several blocking agents in decreasing adventitious adherence of this organism to plastic. Adherence of two strains of S. dysgalactiae (UT516 and UT519) was higher to a transformed mammary epithelial cell line (2.85% and 0.83%, respectively) than to primary bovine mammary epithelial cells (0.45% and 0.52%, respectively). Measurement of the extent of bacterial adherence to cell monolayers showed that adherence was affected by inoculum size. This indicated that the process was mediated by saturable cell receptors and allowed selection of bacteria:epithelial cell ratios not approaching saturating conditions (< 1500:1). In addition, reduction of bacterial adherence by more than 90% following cell fixation indicated that cell surface proteins played a major role in this process. Delineation of bacterial and epithelial cell factors influencing adherence of S. dysgalactiae to mammary epithelial cell monolayers resulted in the development of an in vitro method for quantifying bacterial adherence to cell monolayers.

Molecular genetic characterization of new bovine kappa-casein alleles CSN3F and CSN3G and genotyping by PCR-RFLP

In order to characterize the two new kappa-casein variants F and G (CSN3F and CSN3G) recently detected in Ayrshire and Pinzgauer cattle, exon IV of CSN3 from heterozygous animals was amplified by polymerase chain reaction (PCR), cloned and sequenced. The sequencing data revealed single point mutations at nucleotide positions 10530 (G-->A) for CSN3F and 10790 (C-->T) for CSN3G, corresponding to amino acid exchanges in positions 10 (Arg-->His) and 97 (Arg-->Cys) respectively. These mutations alter recognition sites for the restriction enzymes HhaI and MaeII, which were subsequently used to confirm these polymorphisms in cattle carrying CSN3F or CSN3G. A PCR-restriction fragment length polymorphism (RFLP) genotyping procedure for all currently known CSN3 alleles (CSN3A, CSN3B, CSN3C, CSN3E, CSN3F, CSN3G) was developed.

Association between milk protein genetic variants and genetic values of Canadian Holstein bulls for milk yield traits

The kappa-casein, beta-casein, and beta-lactoglobulin genotypes of 566 bulls were identified by polymerase chain reaction. The associations of these milk protein types with the daughter yield deviations of the 566 bulls for milk, fat, and protein were examined with a mixed model analysis using an animal model. The results suggest that kappa-casein and beta-casein loci had no significant effects on ETA of the bulls for milk, fat, and protein. The effect of beta-lactoglobulin on ETA of protein approached significance. Results suggest that increasing the frequency of the A variant of beta-lactoglobulin in young bulls entering progeny testing improves ETA for protein of the bulls, but the expected improvement is limited.

Genetic variation in domestic reindeer and wild caribou in Alaska

Reindeer (Rangifer tarandus tarandus) were introduced into Alaska 100 years ago and have been maintained as semidomestic livestock. They have had contact with wild caribou (R.t.granti) herds, including deliberate crossbreeding and mixing in the wild. Reindeer have considerable potential as a domestic animal for meat or velvet antler production, and wild caribou are important to subsistence and sport hunters. Our objective was to quantify the genetic relationships of reindeer and caribou in Alaska. We identified allelic variation among five herds of wild caribou and three herds of reindeer with DNA sequencing and restriction enzymes for three loci: a DQA locus of the major histocompatibility complex (Rata-DQA1), kappa-casein and the D-loop of mitochondrial DNA. These loci are of interest because of their potential influence on domestic animal performance and the fitness of wild populations. There is considerable genetic variation in reindeer and caribou for all three loci, including five, three and six alleles for DQA, kappa-casein and D-loop respectively. Most alleles occur in both reindeer and caribou, which may be the result of recent common ancestry or genetic introgression in either direction. However, allele frequencies differ considerably between reindeer and caribou, which suggests that gene flow has been limited.

Applications of DNA amplification techniques in veterinary diagnostics

An overview of the principles of the polymerase chain reaction, ligase chain reaction, self-sustained sequence replication and Q beta replicase is given. The application of these methods for the diagnosis of veterinary infectious and hereditary diseases as well as for other diagnostic purposes is discussed and comprehensive tables of reported assays are provided. Specific areas where these DNA-based amplification methods provide substantial advantages over traditional approaches are also highlighted. With regard to PCR-based assays for the detection of viral pathogens, this article is an update of a previous review by Belák and Ballagi-Pordány (1993).

Kappa-casein polymorphisms among cattle breeds and bison herds

We identified the HindIII restriction site polymorphism of kappa-casein in cattle reported by Pinder et al. (Animal Genetics 22, 11, 1991) and found an additional polymorphism (RsaI) in cattle and bison. The HindIII and RsaI restriction sites were mapped and three haplotypes (alleles) were identified. Preliminary screening of 39 cattle and 71 bison revealed one allele restricted to cattle, one restricted to bison, and one shared by the species. No fixed allelic differences were observed among cattle breeds or among bison herds or subspecies.

Chromosome substitution effects associated with kappa-casein and beta-lactoglobulin in Holstein cattle

Allelic variants of kappa-casein and beta-lactoglobulin were used to estimate chromosome substitution effects on transmitting abilities for yield traits among sons of two Holstein sires. Sire 1 was a heterozygote for both loci, whereas sire 2 was a heterozygote for beta-lactoglobulin only. Transmitting abilities for fat percentage and the exchange of protein and fat (protein yield minus fat yield) were influenced by kappa-casein genotype among offspring of sire 1. The B allele of kappa-casein was associated with a decrease in fat percentage, whereas fat yield was not affected; the result was 4.5 kg more transmitting ability for protein than for fat. Favorable chromosome substitution effects on transmitting abilities for fat percentage, protein yield, and the exchange of protein and fat were also observed for the A allele of beta-lactoglobulin among offspring of sire 1; there were consistent but not significant estimates for sire 2. These results suggest that different estimates could be obtained from offspring of different parents, perhaps from linkage disequilibrium between families. The chromosome substitution effects appeared to be in the direction opposite to the average correlation of milk fat and protein content; marker-assisted selection for increased yield of protein would result in decreased fat yield.

Confirmation of assignment of the bovine K-casein locus by PCR

The provision of a bovine gene map will allow the ready identification of genetic disease in cattle and will lead to the identification of the genetic loci responsible for quantitative traits of economic importance. An extension of the polymerase chain reaction to the identification of linkage in bovine-Chinese hamster cell hybrids has improved the speed and facility of the assignment of genes to linkage groups and thus makes it easier to achieve a bovine linkage map.

Expression of bovine inhibin beta subunit in Escherichia coli

1. A DNA fragment encoding the beta subunit of bovine inhibin was amplified using the polymerase chain reaction and was cloned in plasmids pUC8 and pUR291. 2. Cultures of Escherichia coli TG2 harbouring pKDK37, a pUR291-derived recombinant plasmid, produced a novel protein with a molecular weight of 130,000 corresponding to a beta-galactosidase-inhibin beta fusion protein. 3. The fusion protein was purified from inclusion bodies by solubilization in 8 M urea followed by an ion-exchange and gel permeation chromatography. 4. Analysis by immunoblotting and competitive radioimmuno assay revealed that the fusion protein was recognized by a monoclonal antibody raised against a chemically synthesized peptide for amino acid residues from +82 to +114 of the beta subunit of the bovine inhibin thereby confirming its identity.