Correlated Responses in Two Traits when Selection is Practised on their Ratio

In many fields of application in plant breeding and crop science, ratios of two component traits X and Y are of interest (harvest index in cereals, leaf-to-stem ratio in forage legumes, height-to-diameter ratio in forest trees etc.). When selection is practised on the ratio X/Y of two traits X and Y, the experimenter may be interested in the resulting changes of both trait means. Based on improved approximations for the covariances between X and X/Y and between Y and X/Y and for the variance of X/Y the changes in the means of X and Y can be predicted by applying the regression approach from conventional selection theory. Explicit expressions for these correlated responses in X and Y when selection is practised on their ratio X/Y are derived and discussed. The different outcomes (decrease, zero change or increase) for the selection pressures on X and Y are characterized by phenotypic coefficients of variation of X and Y, phenotypic and genotypic correlations between X and Y and heritabilities of X and Y.     

Determination of the protease activity in a Cuban strain of Babesia bovis]

The attenuation of a Babesia bovis strain depends on its protease content. The present work evaluates this parameter on a virulent strain, before and after attenuation by quick passages on splenectomized calves. The protease activity at different pH values was determined in protein fractions from the blood of calves. The enzymatic test showed marked differences between the protease content of both substrains.     

Lupus-Type "Anticoagulant" in a Dog With Hemolysis and Thrombosis

A circulating anticoagulant was detected in a 2-year-old Chesapeake Bay Retriever with hemolytic anemia, nephrotic syndrome, thrombocytopenia, polyarthropathy, and pulmonary thromboembolism. A persistent prolongation of the activated partial thromboplastin time (aPTT) was detected, and it did not correct with repeated administration of fresh frozen plasma. The aPTT was still prolonged, with a 1:1 mixture of patient's plasma and normal dog plasma in vitro, suggesting the presence of a circulating inhibitor. Results of assays to characterize the inhibitor were compatible with those described for the lupus anticoagulant in human patients with systemic lupus erythematosus. Paradoxically, patients having the lupus anticoagulant are at increased risk for thrombosis. Pulmonary thromboembolism has been described as a frequent complication of immune-mediated hemolytic anemia in the dog, and the presence of a circulating anticoagulant should be considered as a potential mechanism.     

Comparison of dot blot hybridization, polymerase chain reaction, and virus isolation for detection of bovine herpesvirus-1 (BHV-1) in artificially infected bovine semen.

Bovine semen samples spiked with bovine herpesvirus 1 (BHV-1) were used to compare dot blot hybridization, polymerase chain reaction (PCR), and virus isolation for detection of BHV-1 in bovine semen. The PCR amplification used primers targeting the BHV-1 thymidine kinase gene and a nucleic acid releasing cocktail (GeneReleaser); the PCR product was used as the DNA probe in dot blot hybridization; virus isolation was done in primary bovine fetal testis (BFT) cell cultures. Semen diluted 1:20 in tissue culture medium had the least cytotoxicity and inhibition of viral cytopathic effects in BFT cells, allowing detection of 1 TCID50/100 microL of BHV-1 suspension by virus isolation. The presence of foreign DNA such as bovine sperm DNA or salmon sperm DNA increased the sensitivity of dot blot hybridization in detecting BHV-1, allowing detection of 20,000 TCID50/100 microL of neat semen. The inhibition of PCR amplification of BHV-1 DNA in bovine semen was eliminated by diluting the samples 1:20 in tissue culture medium. The best PCR amplification was obtained when semen was diluted 1:20 and when a reaction buffer of pH 9.0, with 1.0 mM MgCl2 was used. Under these conditions, the PCR followed by ethidium bromide staining of agarose gels could detect 1 TCID20/100 microL of sample, whereas PCR followed by Southern blot hybridization could detect 0.01 TCID50/100 microL of sample.(ABSTRACT TRUNCATED AT 250 WORDS)     

Temporary Bile Diversion in Cats with Experimental Extrahepatic Bile Duct Obstruction

The use of a cholecystostomy catheter for temporary bile diversion was investigated in four cats with experimentally induced extrahepatic bile duct obstruction. Eighteen days after ligation of the common bile duct, a 6.5 F accordion catheter was placed in the gallbladder with a 22 g Hawkins needle-guide system through a paracostal incision. Biochemical parameters and fasting serum bile acids were monitored for 16 days. There were significant decreases in mean total bilirubin, aspartate aminotransferase, and fasting serum bile acids within 72 hours of bile diversion, and in mean alanine aminotransferase within 96 hours. Attitude and appetite improved, and the catheter was tolerated well. Positive bile cultures developed in three cats. Histologic changes in the gallbladder included mucosal ulcerations, a mixed inflammatory cellular infiltration, and fibrosis of the submucosa.     

Two cases of colitis cystica profunda in dogs

Colitis cystica profunda in dogs has been diagnosed in one case only. The two own cases were characterized by repeated, partly bloody diarrhea, vomitus, and painful defecation. The disease was diagnosed by clinical examination and colonoscopy with the ensuing histological examination of biopsy specimens. The disease could be managed by administration of a diet, sulfasalazine and corticosteroids.     

Effect of inoculum density of Macrophomina phaseolina on seedling susceptibility of six conifer species

The severity of charcoal root disease of conifer seedlings (Abies concolor, A. magnified, Pinus jeffreyi, P. lambertiana, and Pseudotsuga menziesii) was a power function of the sclerotial density of the fungus (Macrophomina phaseolina) in nursery soil.     

Quantitative Aspects of Thyroid Scintigraphy With Pertechnetate (99mTcO4) in Cats

Thyroidal ^99mTcO₄(pertechnetate) uptake percentages were determined in unanesthetized euthyroid (n = 13) and hyperthyroid (n = 18) cats. Maximal uptakes were observed 60 minutes after IV injection of the radionuclide and ranged from 0.3 to 3.9% of the dose in euthyroid cats (median 2.23%) and from 5.2% to 23.9% of the dose in hyperthyroid cats (median 14.8%) ( P < .05). There were no overlaps in pertechnetate uptake percentages during any of the intervals evaluated. It is concluded that the optimal time for visualization of the thyroid by ^99mTcO₄-scanning is 60 minutes after IV injection of the radionuclide. Calculation of the percentage uptake is of additional diagnostic value.