A comparative analysis of Mhc DRB3 polymorphism in the American bison (Bison bison).

The degree of genetic polymorphism at the DRB3 locus in the major histocompatibility complex (Mhc) of the North American bison was investigated by PCR and DNA sequence analysis. Nine different alleles were characterized in a selected sample of 20 animals. The genetic distances between alleles were as large as usually found at highly polymorphic Mhc loci in other species. A comparative analysis of the DRB3 polymorphism in bison and cattle revealed an extensive sharing of sequence motifs. The result clearly shows a transspecies persistence of DRB3 allelic lineages in the two species. Consequently a significant amount of Mhc polymorphism has been maintained through the population bottleneck that bison experienced in the late nineteenth century. An analysis of the pattern of sequence polymorphism among bison and cattle DRB3 alleles strongly suggested that interallelic recombination has contributed significantly to the generation of allelic diversity at this locus.

Physical and behavioral findings in a pseudohermaphrodite American bison.

A pseudohermaphrodite American bison (Bison bison) behaved like an adult male when interacting with adult females, but like an adult female when interacting with adult males. Its chromosomes were a normal 60, XX and it had a uterus; but it had bilateral testes rather than ovaries. Skull measurements were intermediate between a bull and a cow. Gonadotrophin levels were typical of ovariectomized domestic cows or steers.

Associations between genetic markers and growth and carcass traits in a paternal half-sib family of Angus cattle.

Segregation of polymorphic marker genes in a paternal half-sib family of Angus cattle was used to detect associations between genetic markers and quantitative traits. The half-sib family selected (n = 146) had a sire that was heterozygous at six polymorphic marker loci; BoLA-A (class I major histocompatibility complex), B, C and F blood group systems, serum transferrin and vitamin D binding protein. Segregation of alleles fit the expected ratios for all marker loci. Performance data analyzed for all half-sibs included birth, 205-d and 365-d adjusted weights and pre- and post-weaning average daily gains. Carcass data for steers (n = 61) included carcass weight, rib-eye area, 12th rib fat thickness, percent kidney, heart and pelvic fat and yield grade. Least squares means were compared for differences in performance and carcass traits between groups of half-sibs that inherited alternative paternal alleles. Significant effects were found for two of the six marker systems. Half-sibs that inherited the chromosomal segment (CS) marked by the RBC-B system BGKOxY2A'O' phenogroup had heavier 205-d (9.1 kg) and 365-d (17.3 kg) adjusted weights, faster preweaning average daily gains (.04 kg) and less fat thickness (-2.6 mm) than sibs that inherited the CS marked by I2Y2E'1Y'. Also, sibs that inherited the CS marked by the BoLA-w2 allele had larger rib-eye areas (4.1 cm2) than sibs that inherited BoLA-w28. These data indicate the probable presence of genes linked to the RBC-B and BoLA systems that affect preweaning growth and lean muscle content.

Blood groups in animals.

The membrane of RBC is literally peppered with a great variety of antigenic determinants (blood factors). Some are fixed genetically, ie, they occur on the RBC of all members of the species under study. Others segregate genetically, ie, they occur on the RBC of some but not all members of the species under study. It is these segregrating determinants that form the blood groups proper, the classic example being blood factors A and B of the ABO system of human blood groups. The number of blood group determinants varies considerably between species (eg, greater than 80 in domestic cattle to only 1 in the new world Camelidae). Genetic analysis has shown that the blood factors belong to one or another of a limited number of blood group systems. Some of these systems, similar to the B system of cattle, are enormously complex, whereas others involve but a single blood factor. The object of the present paper is to report on the extent of genetic variation in blood groups and how information on blood groups is being used clinically.

Acute oral median lethal dose of haloxon and coumaphos in sheep as influenced by plasma A esterase.

Determination of the acute oral medial lethal dose (LD50) of haloxon for lambs classified as to the presence or absence of plasma esterases (A esterase; EsA) rapidly hydrolyzing haloxon revealed markedly different values for the 2 phenotypes of sheep. The LD50 for EsA- lambs was 763 mg/kg of body weight with 95% confidence limits of 543 to 1,072 mg/kg. The acute oral LD50 for EsA+ lambs remains undetermined but was demonstrated to be in excess of 11,392 mg/kg. The acute oral LD50 for a closely related organophosphate (coumaphos) was not different in the 2 phenotypes of sheep.

Blood type analyses of creole-like cattle: a comparison with Longhorns and mixed controls.

Creole-like cattle blood types were compared with a mixed control group and Longhorn data using hemolytic and electrophoretic techniques. Among the hemolytic tests, the crucial B system analyses indicated that 1) the Creole-like animals were more similar to Longhorns than were the controls; 2) the three groups were different from each other; 3) the three groups were not mutually exclusive. Eleven new phenogroups were postulated. The remaining blood group systems and the electrophoretic tests raised interesting biohistorical questions but were generally less useful in discriminating among the three groups of cattle.

Linkage of loci controlling alloantigens on red blood cells and lymphocytes in the horse.

A system of equine lymphocyte alloantigens designated ELA, is identified, and it is shown that the locus or loci controlling these markers must be closely linked to the locus controlling markers in the A system of horse blood groups. Among 29 offspring in two stallion families there was evidence for one recombinant. Lod scores for linkage between the A and ELA loci in the two families were 3.61 and 3.33, respectively, for theta equal to 0.

Subtypic linearity in the bovine B blood group system.

The technique of proteolytic digestion employing the enzymes trypsin, chymotrypsin, and protease was used to investigate the physical order of subtypic determinants occurring on bovine erythrocytes. In the B system subgroup Y1, Y2, the determinants behaved as if linearly arranged in the same order as predicted from their serological behavior; furthermore, the differences between the two subtypes appeared to be quantitative rather than qualitative. In the E'1, E'2, E'3 subgroup, however, the subtypic determinants did not appear to be physically linear, although they are serologically linear.

Leukemia allotransplants in canine fetuses: influence of host age and immune responsiveness.

Myelomonocytic leukemia cells allografted prenatally in some developing purebred Beagle fetuses elicited tumors postnatally in some of the pups. The later in gestation that the inoculum was delivered, the less was the disposition to eventual leukemia, indicating that fetal host age at the time of grafting and tumorigenesis are correlated. The leukemogenic transplants may have grown because of fetal immunoinsufficiency or because they were tolerogenic in the developing immune system. Limited immunologic data for exclusion of the latter possibility are reported.

Use of blood typing to confirm principles of coat-color genetics in horses.

The chestnut rule in equine coat-color genetics asserts that the inter se mating of chestnut horses never produces bay, black, brown or gray offspring. The gray rule asserts that a gray offspring must have at least one gray parent. Nine alleged exceptions to the chestnut rule, all involving bay offspring, and eight alleged exceptions to the gray rule, including four offspring that were also exceptions to the chestnut rule, were examined for parent-offspring genetic incompatibilities in as many as 17 genetic systems of blood-group markers. In all except one of the 17 cases it was possible to show that parentage had been incorrectly assigned. In 9 of the 16 exclusions it was possible to exclude the stallion irrespective of the mare and in one of the 16 exclusions it was possible to exclude the mare irrespective of the stallion. The percentage of exclusions, i.e., 94, was closely in line with expectation based on the established efficacy of these tests, about 90 percent, in excluding the incorrect stallion or stallions in paternity cases. Although the results strongly uphold the validity of the chestnut and gray rules in equine coat-color inheritance, they do not completely exclude the possibility that there could be rare exceptions to one or the other or both color rules. Insofar as equine registries may be concerned, the results clearly indicate that no alleged exception to the color rules should be considered eligible for registry in the absence of these tests.

Equine toxoplasmosis: a survey for antibodies to Toxoplasma gondii in horses.

A nationwide sample of horses was tested to determine the prevalence of toxoplasma antibodies in equine animals. Of 1,294 serum samples from horses tested by the microtitration indirect hemagglutin test, 20% were positive. Among the popular breeds of horses, the following antibody prevalences were found: Arabian, 19%; Paint, 22%; Quarter Horses, 13%; Thoroughbred, 24%; and Standardbred, 17%. The antibody prevalence increased from 2% in horses 1 year of age to 18% in 2-year-olds, and rose to 38% in horses 12 years of age. Significant differences were not evident by broad geographic locations across the United States. However, there were differences in prevalence according to premises where the horses were kept. On some ranches, there was no evidence of infection, whereas up to 67% of the horses on other premises were seropositive for toxoplasmosis.