Genetic Mechanisms of Resistance and Susceptibility to Leukemia in Ayrshire and Black Pied Cattle Breeds Determined by Allelic Distribution of Gene BoLA-DRB3

In the herds of Ayrshire and Black Pied cattle breeds of Russian selection, comparative analysis of allelic distribution of BoLA-DRB3 was performed in animal groups with different status of persistent lymphocytosis (PL) caused by the bovine leukemia virus (BLV). Alleles were typed by PCR–RFLP. Different spectra of BoLA-DRB3 alleles mediating susceptibility and resistance to leukemia were detected in the studied breeds. The role of amino acid motives in 1 domain of BoLA-DRB3 antigens was confirmed: ER (in positions 70–71), in resistance to leukemia and VDTY and VDTV (75–78), in susceptibility to leukemia. The nucleotide sequence of allele BoLA-DRB3.2*7with deletion of codon 65, which resulted in the changed conformation of the corresponding antigen molecule, was associated with resistance to PL. Cows of Black Pied and Ayrshire breeds with genotypes coding VDTY/VDTV (RR = 11.67, P = 0,014) and VDTY/VDTY (RR = 4.71, P = 0.022), respectively, were shown to be susceptible to PL. The role of heterozygosity level was demonstrated (estimated by BoLA-DRB3 alleles and by amino acid motives in positions 75–78 of the antigen) as an unspecific factor of resistance to PL. The lowest heterozygosity level by amino acid motives (75–78) was revealed in PL animals, for which sample inbreeding coefficients were detected: F = 0.324 and 0.084 in Ayrshire and Black Pied breeds, respectively.     

Comparative analysis of Ayrshire and Black Pied cattle breeds by histocompatibility markers

Distribution of BoLA-A antigens and BoLA-DRB3 alleles was studied by means of the microlymphocytotoxic test (BoLA-A) and the PCR-RFLP method (BoLA-DRB3) using restriction endonucleases RSAI, HaeIII, and XhoII in Ayrshire (n = 127) and Black Pied (n = 129) cattle breeds. Comparative analysis of profiles for class I antigens revealed significant differences in the frequencies of antigens W2, W6, W10, W31, W44, W15, and W19 (P > 99%). The studied breeds also differ in the spectrum of BoLA-DRB3 alleles and distribution of their frequencies. Heterogeneous allele frequency profile was detected in Ayrshire cattle: five of 18 detected alleles (DRB3.2*7, *8, *10, *24, and *28) accounted for 77%. Allele DRB3.2*7 (37.6%), which is classed with rare alleles in Black Pied cattle is the most common in Ayrshire cattle. The observed heterozygosity level in the combined sample of Black Pied breed (0.836) is higher than in Ayrshire breed (0.070). In both breeds, the heterozygosity level was studied in the groups of healthy and ill with persistent lymphocytosis (caused by bovine leukemia virus) animals and in the group of virus carriers in Ayrshire breed. In ill animals, a decrease in the observed heterozygosity level was detected, as compared to healthy animals and the expected heterozygosity level. The observed heterozygosity level exceeds the expected one in virus carriers. The detected features of the heterozygosity level in the studied groups allow the heterozygosity level for locus BoLA-DRB3 to be considered a nonspecific factor of resistance to leukemia and are heterozygous animals to have higher resistance to bovine leukemia. The presence of a larger proportion of highly productive animals (the annual productivity of more than 7000 kg) in the group of ill Ayrshire cattle animals, as compared to healthy animals to established. To increase resistance to bovine leukemia, the obtained data indicate the importance of the control of heterozygosity level and genetic diversity for gene BoLA-DRB3 in cattle herds.     

Polymorphism of cattle prolactin gene: microsatellites, PSR-RFLP]

In the samples of Russian Ayrshire and Gorbatov Red cattle breeds, distribution of frequencies of prolactin (PRL) gene alleles generated due to the presence of polymorphic RsaI site in exon 3 were studied. In the breeds, the frequencies of the B allele of the PRL gene (with RsaI(+) site) detected by the PCR-RFLP method were 14.1 and 8.6%, respectively. In Black Pied, Ayrshire and Gorbatov Red cattle breeds, variation of the microsatellite dinucleotide repeat in the regulatory region of the gene PRL was also studied. Gorbatov Red breed was monomorphic at the microsatellite locus with the only allele 164 bp in length. Two alleles (164 bp and 162 bp) were detected in the other breeds studied. The frequencies of 164-bp allele of the microsatellite locus were 93.7 and 90.0% in Black Pied and Ayrshire breeds, respectively. In Gorbatov Red breed of dairy type with good beef qualities and low milk-fat yield, lower level of heterozygosity for PRL gene was demonstrated compared to Ayrshire and Black Pied breeds with high milk-fat yield. In three cattle breeds, higher mean estimate of polymorphism information content of PCR-RFLP in exon 3 (PIC = 0.21) was revealed compared with the same estimate (PIC = 0.09) for the microsatellite locus variability in the regulatory region of the PRL gene. Characteristics of allele B distribution of the PRL gene in the representatives of the Bovidae family are considered.     

Polymorphism of Bovine Prolactin Gene: Microsatellites,PCR–RFLP

In the samples of Russian Ayrshire and Gorbatov Red cattle breeds, distribution of frequencies of prolactin (PRL) gene alleles generated due to the presence of polymorphic RsaI site in exon 3 were studied. In the breeds, the frequencies of the Ballele of the PRLgene (with RsaI(+) site) detected by the PCR–RFLP method were 14.1 and 8.6%, respectively. In Black Pied, Ayrshire and Gorbatov Red cattle breeds, variation of the microsatellite dinucleotide repeat in the regulatory region of the gene PRLwas also studied. Gorbatov Red breed was monomorphic at the microsatellite locus with the only allele 164 bp in length. Two alleles (164 bp and 162 bp) were detected in the other breeds studied. The frequencies of 164-bp allele of the microsatellite locus were 93.7 and 90.0% in Black Pied and Ayrshire breeds, respectively. In Gorbatov Red breed of dairy type with good beef qualities and low milk-fat yield, lower level of heterozygosity for PRLgene was demonstrated compared to Ayrshire and Black Pied breeds that have high milk-fat yield. In three cattle breeds, higher mean estimate of polymorphism information content of PCR–RFLP in exon 3 (PIC = 0.21) was revealed compared with the same estimate (PIC = 0.09) for the microsatellite locus variability in the regulatory region of the PRLgene. Characteristics of allele Bdistribution of thePRLgene in the representatives of the Bovidae family are considered.     

Polymorphism of the <Emphasis Type="Italic">BoLA-DRB3</Emphasis> gene in the Mongolian,Kalmyk, and Yakut cattle breeds

Polymorphism of the BoLA-DRB3 gene was studied with the use of the PCR-RFLP technique in three cattle breeds (Mongolian, Kalmyk, and Yakut) representing the Bos taurus turano-mongolicus group. 35 BoLA-DRB3.2 alleles were detected in the Mongolian breed and 34 alleles in the Kalmyk breed. The frequencies of alleles in both populations are distributed rather evenly: the frequencies of the most widely represented alleles (*18, *20, and *28) in the Mongolian cattle varied from 7.75 to 8.45%. The most frequent alleles in the Kalmyk cattle were *28 (14.52%), *24 (7.26%), and *12 (6.45%). Only five alleles were identified in the Yakut cattle breed. The prevailing allele was *29 (77.3%); a relatively frequent allele was *1 (13.1%), and the remaining three alleles constituted only 9.6%. Such a low level of diversity of BoLA-DRB3 gene alleles was not observed earlier in any other cattle breed. The Mongolian and Kalmyk breeds showed a wide diversity of BoLA-DRB3 genotypes (56 and 51 genotypes, respectively) and a high level of expected heterozygosity (H _e = 0.953 and 0.946, respectively). Both breeds had a deficiency of heterozygotes (Mongolian cattle: H _o = 0.775, D = −0.187; Kalmyk cattle: H _o = 0.708, D = −0.252). A low level of genotypic diversity for the BoLA-DRB3 locus (only seven genotypes; the frequency for the genotype *29/*29 is 71.4%) and a very low level of observed heterozygosity (H _o = 0.12) were revealed in the Yakut breed. BoLA-DRB3.2 alleles associated with resistance to persistent lymphocytosis caused by the bovine leukemia virus (total frequencies 15.49 and 24.19%) and to various forms of mastitis (total frequencies 12.68 and 20.96%, respectively) were identified in the Mongolian and Kalmyk animals. In the Yakut breed, alleles associated with resistance to diseases are represented only by the BoLA-DRB3.2 allele *7 (1.2%). Thus, the Mongolian and Kalmyk cattle breeds are characterized by a wide diversity of alleles and genotypes for the BoLA-DRB3 gene. In contrast, the population of Yakut cattle from the Verkhoyanskii region of the Republic of Sakha has a poor diversity of alleles and genotypes for the BoLA-DRB3 gene and a very low level of heterozygosity, suggesting an unfavorable state of the population that is probably caused by inbreeding depression due to a long-term isolation and a small number of animals.     

Expressed 2-5A synthetase genes and pseudogenes in the marine sponge Geodia barretti

In cattle, bovine leukocyte antigens (BoLAs) have been extensively used as markers for bovine diseases and immunological traits. In this study, we sequenced alleles of the BoLA class II loci, BoLA-DRB3 and BoLA-DQA1, from 650 Japanese cattle from six herds [three herds (507 animals) of Japanese Black cattle and three herds (143 animals) of Holstein cattle] using polymerase chain reaction-sequence-based typing (PCR-SBT) methods. We identified 26 previously reported distinct DRB3 alleles in the two populations: 22 in Japanese Black and 17 in Holstein. The number of DRB3 alleles detected in each herd ranged from 9 to 20. Next, we identified 15 previously reported distinct DQA1 alleles: 13 in Japanese Black and 10 in Holstein. The number of alleles in each herd ranged from 6 to 10. Thus, allelic divergence is significantly greater for DRB3 than for DQA1. A population tree on the basis of the frequencies of the DRB3 and DQA1 alleles showed that, although the genetic distance differed significantly between the two cattle breeds, it was closely related within the three herds of each breed. In addition, Wu-Kabat variability analysis indicated that the DRB3 gene was more polymorphic than the DQA1 gene in both breeds and in all herds, and that the majority of the hypervariable positions within both loci corresponded to pocket-forming residues. The DRB3 and DQA1 heterozygosity for both breeds within each herd were calculated based on the Hardy-Weinberg equilibrium. Only one Japanese Black herd showed a significant difference between the expected and observed heterozygosity at both loci. This is the first report presenting a detailed study of the allelic distribution of BoLA-DRB3 and -DQA1 genes in Japanese Black and Holstein cattle from different farms in Japan. These results may help to develop improved livestock breeding strategies in the future.     

Relations between genetic distance of parental pig breeds and heterozygosity of their F1 crosses measured by genetic markers

The aim of this paper is to examine the extent to which increment of heterozygosity in F₁ crosses can be predicted from genetic distance of parental breeds. For this purpose, 38 polymorphic marker loci (blood groups, allotypes, polymorphic proteins and enzymes) were tested in 1115 purebred animals (Duroc, Hampshire and Czech Meat Pig as sire breeds; Landrace, Large White and Black Pied Přeštice as dam breeds) and in 1428 crossbred animals of the resulting nine crossbred groups. The number of animals in each genetic group ranged from 75 to 230. On the basis of the allele frequencies of the scored loci, three measures of genetic diversity (heterozygosity, standardized heterozygosity, effective number of alleles) were calculated in all 15 genetic groups. Furthermore, two measures of genetic distance (Nei's standard genetic distance and Gregorius' absolute genetic distance) were calculated between the parental populations. High correlations (Pearson product-moment correlation 0.62 to 0.73; Spearman rank correlation 0.58 to 0.85) were found between the increment of heterozygosity in the crosses (in relation to the mean of the heterozygosities of parental populations) and the genetic distance between the parental populations.     

Analysis and frequency of bovine lymphocyte antigen (BoLA-DRB3) alleles in Iranian Holstein cattle

The bovine lymphocyte antigen (BoLA-DRB3) gene encodes cell surface glycoproteins that initiate immune response by presenting processed antigenic peptides to CD4 T helper cells. DRB3 is the most polymorphic bovine MHC class II gene which encodes the peptide-binding groove. DRB3 gene has been extensively evaluated as a candidate marker for association with various bovine diseases and immunological traits. This study describes genetic variability in the BoLA-DRB3 in Iranian Holstein cattle. This is the first study of the DNA polymorphism of the BoLA-DRB3 gene in Iranian Holstein cattle. Hemi-nested PCR-RFLP method is used for identification the frequency of BoLA-DRB3 alleles. The BoLA-DRB3 locus is highly polymorphic in the studied herd (26 alleles). Almost 67% of the alleles were accounted for four alleles (BoLA-DRB3.2*8, *24, *11 and *16) in Iranian Holstein cattle. The DRB3.2*8 allele frequency (26.6%) was higher than the others. The frequencies of the DRB3.2*54, *37, *36, *28, *25, *14, *13, *10, *1 alleles were lower than 1%. Significant distinctions have been found between Iranian Holstein cattle and other cattle breeds studied. In Iranian Holstein cattle the alleles (BoLA-DRB3.2*22, *2 and *16) associated with a lower risk of cystic ovarian disease in Holstein cattle are found. The alleles associated with the resistance to mastitis and to bovine leukemia virus infection BoLA-DRB3.2*11 and *23 are detected with the frequencies 10.4% and 4.4%, respectively. Thus in the Iranian Holstein cows studied are found alleles which are associated with resistance to various diseases. The method of DNA-typing of animals can be used in agricultural practice for BoLA-DRB3 allele genotyping of cattle in order to reduce spreading of alleles providing susceptibility to mastitis or leukemia in cattle herds.     

Allelic polymorphism of kappa-casein gene (CSN3) in Russian cattle breeds and its informative value as a genetic marker

The frequencies of the kappa-casein gene (CSN3) alleles and genotypes have been determined in five Russian cattle breeds (Bestuzhev, Kalmyk, Russian Black Pied, Yaroslavl, and Yakut breeds) by means of PCR-RFLP analysis using two independent restriction nucleases (HinfI and TaqI) and by allele-specific PCR. Typing alleles A and B of CSN3 is of practical importance, because allele B is correlated with commercially valuable parameters of milk productivity (protein content and milk yield) and improves the cheese yielding capacity. The frequencies of the B allele of CSN3 in the breeds studied vary from 0.16 to 0.50; and those of the AB and BB genotypes, from 0.27 to 0.60 and from 0.02 to 0.23, respectively. The Yaroslavl breed had the highest frequencies of CSN3 allele B and genotype BB (0.50 and 0.23, respectively). The frequencies of the B allele and BB genotype in other breeds studied varied from 0.25 to 0.32 and from 0.03 to 0.09, respectively. In none of the breeds studied have the observed and expected heterozygosities been found to differ from each other significantly. However, the observed genotype distributions significantly differ from the expected one in some herds (in most such cases, an excess of heterozygotes is observed). Two herds of the Yaroslavl breed dramatically differ from each other in the heterozygosity level: a deficit (D = -0.14) and an excess (D = 0.20) of heterozygotes have been observed at the Mikhailovskoe and Gorshikha farms, respectively. In general, however, the heterozygosity of the Yaroslavl breed corresponds to the expected level (D = 0.04). Analysis of breeds for homogeneity with the use of Kulback's test has shown that all cattle breeds studied are heterogeneous, the CSN3 diversity within breeds being higher than that among different breeds, which is confirmed by low Fst values (0.0025-0.0431). Thus, a DNA marker based on CSN3 gene polymorphism is extremely important for breeding practice as a marker of milk quality; however, it is inapplicable to marking differences between breeds or phylogenetic relationships between cattle breeds because of the high diversity with respect to this locus within breeds.     

Restriction Fragment Length Polymorphism (RFLP) in Exon 2 of the BoLA-DRB3 Gene in South American Cattle

The Bola-DRB3 gene participates in the development of the immune response and is highly polymorphic. For these reasons, it has been a candidate gene in studies of the genetic basis of disease resistance and in population genetic analysis. South American native cattle breeds have been widely replaced by improved exotic breeds leading to a loss of genetic resources. In particular, South American native breeds have high levels of fertility and disease resistance. This work describes genetic variability in the BoLA-DRB3 gene in native (Caracu, Pantaneiro, Argentinean Creole) and exotic (Holstein, Jersey, Nelore, Gir) cattle breeds in Brazil and Argentina. PCR-RFLP alleles were identified by combining the restriction patterns for the BoLA-DRB3.2 locus obtained with RsaI, BstY and HaeIII restriction enzymes. Allelic frequencies and deviations from the Hardy-Weinberg equilibrium were also calculated. Analysis of the 24 BoLA-DRB3 PCR-RFLP alleles identified showed differences in the allele distributions among breeds.     

Analysis and Frequency of Bovine Lymphocyte Antigen (BoLA-DRB3) Alleles in Iranian Holstein Cattle

The bovine lymphocyte antigen (BoLA-DRB3) gene encodes cell surface glycoproteins that initiate immune response by presenting processed antigenic peptides to CD4 T helper cells. DRB3 is the most polymorphic bovine MHC class II gene which encodes the peptide-binding groove. DRB3 gene has been extensively evaluated as a candidate marker for association with various bovine diseases and immunological traits. This study describes genetic variability in the BoLA-DRB3 in Iranian Holstein cattle. This is the first study of the DNA polymorphism of the BoLA-DRB3 gene in Iranian Holstein cattle. Hemi-nested PCR-RFLP method is used for identification the frequency of BoLA-DRB3 alleles. The BoLA-DRB3 locus is highly polymorphic in the studied herd (26 alleles). Almost 67% of the alleles were accounted for four alleles (BoLA-DRB3.2*8, *24, *11, and *16) in Iranian Holstein cattle. The DRB3.2*8 allele frequency (26.6%) was higher than the others. The frequencies of the DRB3.2*54, *37, *36, *28, *25, *14, *13, *10, *1 alleles were lower than 1%. Significant distinctions have been found between Iranian Holstein cattle and other cattle breeds studied. In Iranian Holstein cattle the alleles (BoLA-DRB3.2*22, *2, and *16) associated with a lower risk of cystic ovarian disease in Holstein cattle are found. The alleles associated with the resistance to mastitis and to bovine leukemia virus infection BoLA-DRB3.2*11 and *23 are detected with the frequencies 10.4 and 4.4%, respectively. Thus, in the Iranian Holstein cows studied alleles associated with resistance to various diseases are found. The method of DNA-typing of animals can be used in agricultural practice for BoLA-DRB3 allele genotyping of cattle in order to reduce spreading of alleles providing susceptibility to mastitis or leukemia in cattle herds.__________From Genetika, Vol. 41, No. 6, 2005, pp. 817–822.Original English Text Copyright © 2005 by Nassiry, Eftekhar Shahroodi, Mosafer, Mohammadi, Manshad, Ghazanfari, Mohammad Abadi, Sulimova.The article was submitted by the authors in English.     

Distribution of <Emphasis Type="Italic">BoLA-DRB3</Emphasis> allelic frequencies and identification of a new allele in the Iranian cattle breed Sistani (<Emphasis Type="Italic">Bos indicus</Emphasis>)

The distribution of the frequencies of BoLA-DRB3 gene alleles in the Iranian cattle breed Sistani was studied by the PCR-RFLP (“hemi-nested”) assay using restriction endonucleases RsaI, HaeIII and BstYI. In the examined cattle breed (65 animals) 32 alleles have been identified one of which being described for the first time (6.15% frequency). The nucleotide sequence of the polymorphic region of exon 2 of this allele has been determined and submitted in the GenBank database under accession number DQ486519. The submitted sequence has maximum homology (92%) with the previously described sequence DRB3-mRNA from Bos indicus (AccN X79346) and differs from it by 24 nucleotide substitutions which result in 16 amino acid substitutions. The peptide (on the basis of the reconstructed amino acid sequence) has 89% identity to the sequence encoded by the BIDRBF 188 locus (Bos indicus). The results obtained permit the sequence described by us to be considered as a new allele of the BoLA-DRB3 gene (DRB3.2 ^* X). The total frequency of the main six alleles (DRB3.2*8, *10, *11, *20, *34 and *X) occurring with a frequency of over 5% is about 60% in Iranian Sistani cattle. Fifteen alleles have <1% frequency. The highest frequency was observed for DRB3.2*8 allele (21.54%) like in other previously described breeds of Bos indicus (up to 23.07%). The Iranian breed Sistani has a high level of similarity by the spectrum of BoLA-DRB3 alleles and their frequencies to other Bos indicus breeds and significantly differs by these criteria from the Bos Taurus breeds. The Iranian Sistani herd under study includes alleles associated with to resistance to leukemia (DRB3.2*11 and *23) and to different forms of mastitis (DRB3.2* 2, *7, *11, *23 and *24) although their frequencies are low (from 0.77 to 5.37%). On the whole, a high level of diversity of BoLA-DRB3 gene alleles and the availability of alleles associated with resistance to different diseases makes this breed of interest for breeding practice. The article is published in the original.     

Gene Frequency Distribution of the BoLA-DRB3 Locus in Saavedreño Creole Dairy Cattle

The objective of this study is to describe the gene frequency distribution of the bovine lymphocyte antigen (BoLA)-DRB3 locus in Saavedreño Creole dairy cattle and to compare it with previously reported patterns in other cattle breeds. One hundred and twenty-five Saavedreño Creole dairy cattle were genotyped for the BoLA-DRB3.2 allele by polymerase chain reaction and restriction fragment length polymorphism. Twenty-two out of 53 previously identified BoLA-DRB3.2 alleles were detected, with gene frequencies ranging from 0.4 to 16.8%. Seventy percent of the variation corresponded to the seven most frequent alleles (BoLA-DRB3.2*7, *8, *11, *16, *27, *36, and *37). The studied population exhibits a high degree of expected heterozygosity (h _e = 0.919). The F _IS index did not show significant deviation from Hardy-Weinberg equilibrium. However, the neutrality test showed an even gene frequency distribution. This result could be better explained assuming balancing selection instead of neutral or positive selection for one or a few alleles. In conclusion, the results of this study demonstrated that BoLA-DRB3.2 is a highly polymorphic locus in Saavedreño Creole dairy cattle, with significant variation in allele frequency among cattle breeds.     

Identification and characterization of new BoLA-DRB3 alleles by heteroduplex analysis and direct sequencing

A sample of 52 mixed-breed dairy cattle (Holstein Friesian and Jersey) and 51 beef cattle (Hereford) from south-east Queensland was studied. The second exon of BoLA-DRB3 was amplified by polymerase chain reaction (PCR), and polymorphisms were detected by heteroduplex analysis. A large number of different heteroduplex patterns indicated extensive sequence polymorphism. Direct sequencing of PCR products from 17 homozygotes and cloning and sequencing of PCR product from two heterozygotes resulted in the identification and characterization of four novel alleles. The previously described allele BoLA-DRB3 * 2A is characterized by an amino acid deletion at position 65. We have identified three animals that are homozygous for this amino acid deletion, indicating that the deletion is unlikely to result in loss of function. Two of these animals had allele BoLA-DRB3 * 2A, and one had a novel allele with codon 65 deleted but differing from BoLA-DRB3 * 2A at a number of other amino acid positions. In conclusion, heteroduplex analysis allows rapid discrimination between homozygotes and heterozygotes, and enables rapid identification of new BoLA-DRB3 alleles.     

Polymorphism of intron 2 of the SDF1 gene in Galloway, Hereford, and Russian Black Pied cattle

The region of intron 2 of the SDF1 gene encoding a chemokine of the CXC subfamily has been resequenced in Galloway, Hereford, and Black Pied cattle. Five of the single-nucleotide polymorphisms (SNPs) that were earlier detected by other authors in various breeds of cattle in North America (99C/G, 128T/C, 206C/T, 267C/G and 313C/T) have been found. The 270insC polymorphic marker has proved to be monomorphic in Russian cattle breeds. Hereford cattle significantly differ from Galloway and Black Pied cattle in the frequencies of some SNP variants and their combinations. The number of SNP combinations in Hereford and Galloway cattle exceeds that in Black Pied cattle.     

Indigenous domestic breeds as reservoirs of genetic diversity: the Argentinean Creole cattle

Contrary to highly selected commercial breeds, indigenous domestic breeds are composed of semi-wild or feral populations subjected to reduced levels of artificial selection. As a consequence, many of these breeds have become locally adapted to a wide range of environments, showing high levels of phenotypic variability and increased fitness under natural conditions. Genetic analyses of three loci associated with milk production (alpha(S1)-casein, kappa-casein and prolactin) and the locus BoLA-DRB3 of the major histocompatibility complex indicated that the Argentinean Creole cattle (ACC), an indigenous breed from South America, maintains high levels of genetic diversity and population structure. In contrast to the commercial Holstein breed, the ACC showed considerable variation in heterozygosity (H(e)) and allelic diversity (A) across populations. As expected, bi-allelic markers showed extensive variation in He whereas the highly polymorphic BoLA-DRB3 showed substantial variation in A, with individual populations having 39-74% of the total number of alleles characterized for the breed. An analysis of molecular variance (AMOVA) of nine populations throughout the distribution range of the ACC revealed that 91.9-94.7% of the total observed variance was explained by differences within populations whereas 5.3-8.1% was the result of differences among populations. In addition, the ACC breed consistently showed higher levels of genetic differentiation among populations than Holstein. Results from this study emphasize the importance of population genetic structure within domestic breeds as an essential component of genetic diversity and suggest that indigenous breeds may be considered important reservoirs of genetic diversity for commercial domestic species.     

Polymorphisms in MHC-DRA and -DRB alleles of water buffalo (Bubalus bubalis) reveal different features from cattle DR alleles

Seventy-five individuals of Bubalus bubalis belonging to four different breeds, three of river buffalo and one of swamp buffalo, were studied for polymorphism in MHC DRB (Bubu-DRB) and DRA (Bubu-DRA) loci. Eight alleles of Bubu-DRB were found, and all alleles in the swamp type were shared with the three river breeds. All alleles sampled from the breed of European origin (Mediterranean) were present in breeds sampled in Brazil, thus variability of this locus may have been preserved to a great extent in the more recently founded Brazilian population. Bubu-DRB alleles contained higher proportions of synonymous vs. non-synonymous substitutions in the non-peptide-binding sites (PBS) region, in contrast to the pattern of variation found in BoLA-DRB3, the orthologous locus in cattle. This indicated that either the first domain exon (exon 2) of Bubu-DRB has not undergone as much recombination and/or gene conversion as in cattle alleles, or Bubu-DRB may be more ancient than BoLA-DRB3 alleles. Phylogenetic analysis of DRB alleles from Bubalus, Syncerus c. caffer, the Cape buffalo, and domestic cattle demonstrated transspecies polymorphism. Water buffalo contained two alleles of DRA that differed from each other in two amino acid positions, including one in the PBS (alpha22) that was also shared with Anoa depressicornis, the anoa. Discovery of variation in DRA was surprising as the first domain of DRA is a highly conserved polypeptide in mammals in general and especially in ruminants, where no other substitution in PBS was seen.     

Polymorphism of intron 2 of the <Emphasis Type="Italic">SDF1</Emphasis> gene in Galloway,Hereford, and Russian Black Pied cattle

The region of intron 2 of the SDF1 gene encoding a chemokine of the CXC subfamily has been resequenced in Galloway, Hereford, and Black Pied cattle. Five of the single-nucleotide polymorphisms (SNP) that were earlier detected by other authors in various breeds of cattle in North America (99C/G, 128T/C, 206C/T, 267C/G and 313C/T) have been found. The 270insC polymorphic marker has proved to be monomorphic in Russian cattle breeds. Hereford cattle significantly differ from Galloway and Black Pied cattle in the frequencies of some SNP variants and their combinations. The number of SNP combinations in Hereford and Galloway cattle exceeds that in Black Pied cattle.     

Association between BoLA-DRB3 and somatic cell count in Holstein cattle from Argentina

Different studies have proved that the resistance/susceptibility to mastitis is genetically determined. The major histocompatibility complex in cows is known as bovine lymphocyte antigen (BoLA). Genes from the BoLA have been associated with the occurrence of infectious diseases such as mastitis and leukosis, especially the BoLA-DRB gene. The object of the present study was to detect associations between BoLA-DRB3 alleles and somatic cell count (SCC), as an indicator of resistance/susceptibility to mastitis in Holstein cattle (N = 123) from La Pampa, Argentina. Fisher's exact test and Woolf-Haldane odds ratio were applied to study the association between SCC and BoLA-DRB3 allele frequencies. Significant association was noted between BoLA-DRB3.2*23 and *27 alleles (p < 0.05) and protective or susceptibility effects, respectively. In addition, alleles BoLA-DRB3.2*20 and *25 exhibit suggestive association with high SCC (p < 0.1). These results were partially in agreement with data reported from Japanese Holstein cattle, but differed from those published by other authors. A possible explanation for the contrasting results could be that the mastitis is a multifactor disease caused by different pathogens. Moreover, most of the studies were carried out using PCR-RFLP method, which has less resolution than PCR-SBT because PCR-RFLP defined alleles included more than one sequenced alleles.