Characterization of Newcastle disease viruses isolated from field cases in Japan

Seven Newcastle disease viruses isolated in Japan from 1930 to 1984 were cloned on chicken embryo fibroblasts (CEFs) and characterized biologically. All seven produced two or more types of plaques on CEFs. The plaques were classified into four types. Plaque cloning was carried out five times, and 22 cloned viruses were established. The biological characters of the cloned viruses suggested that the strains contain different clones and that their clones are different even among close cases, such as G strain and H strain.     

Properties of nine continuous B-cell lines established from enzootic bovine leukosis tumors.

We established 9 cell lines from 63 tumor cases of enzootic bovine leukosis and studied their properties. Cells of all lines formed small clumps and floated in culture medium, indicating growth. Four of the 9 cell lines were surface immunoglobulin (SIg)-positive, but the remaining 5 line cells were negative for SIg or, if SIg was detected, the percentage of SIg-positive cells was very low. Tests for the properties of the cells with monoclonal antibodies to lymphocytes revealed that the established line cells are B-lymphocytes. Morphological observation also revealed that they had the morphology of B-lymphoblastic cell. The results of E and EAC rosette assay were negative, but 6 of 8 cell lines were positive for EA rosetting. All the 9 cell lines reacted with MoAb C-143, which recognizes the tumor-associated antigen (TAA) of the EBL tumor cell. All 9 cell lines produced bovine leukosis virus (BLV). These results suggest that the 9 cell lines are tumor cells derived from B-lymphocytes of EBL.     

Tryptophan availability of some feedstuffs determined by pig growth assay

Three experiments were conducted with young pigs to measure the availability of tryptophan in soybean meal, meat and bone meal, cottonseed meal, corn and sorghum. In Exp. 1, a 17.5% crude protein corn and gelatin-based diet, deficient in tryptophan, was supplemented with graded levels of L-tryptophan to establish the growth response of 10- to 20-kg pigs to graded additions of dietary tryptophan. From these data the requirement for maximal growth was calculated to be .16% of the diet using a broken-line model. In Exp. 2, the effects of excess amino acids in a test feedstuff, i.e., soybean meal, on the growth assay method for estimating tryptophan availability was evaluated. The addition of excess crystalline amino acids to the basal diet in proportions equal to the excesses contributed by a test level of soybean meal resulted in a 17.7 percentage unit reduction in the estimate of tryptophan availability (82.3%). When the standard diet was supplemented with amino acids to provide the pattern of excess amino acids found in the corn-gelatin basal diet with added soybean meal, the availability of tryptophan in soybean meal was estimated to be 95.2%. In Exp. 3, the tryptophan availabilities for meat and bone meal, cottonseed meal, corn and sorghum were estimated to be 82.2%, 80.9%, 94.0% and 86.4%, respectively. The diets used in this experiment were supplemented to contain excesses of individual amino acids in the same proportions as found in the basal diet, with the test feed ingredient added as a source of tryptophan. In these experiments the tryptophan content of the various feedstuffs was measured by ion-exchange liquid chromatography following alkaline hydrolysis.     

Prevalence of circulating antibodies to p10, a non-structural protein of the Borna disease virus in cats with ataxia.

Japanese domestic cats were surveyed for circulating antibodies to the plO and p24 proteins of the Borna disease virus (BDV) by Western blotting. Twenty-four of 52 cats (46.2%) with ataxia and other neurologic symptoms of unknown cause were positive for antibodies to BDV p10 and/or p24. In contrast, cats without neurological symptoms gave a significantly lower prevalence of anti-BDV antibodies to p10 and/or p24 (36 of 152 cats, 23.7%). Thirty specific pathogen-free (SPF) cats tested as controls were uniformly negative to BDV pl0 and p24 antigens. These results suggest that BDV may play a role in ataxia in cats. Additionally, our results suggest that it is necessary to use both p10 and p24 as antigens to detect circulating antibodies to BDV in cats.     

An outbreak of copper poisoning in Mute swans (Cygnus olor).

Eight of 9 Mute swans (Cygnus olor) untied in the river acrossing the central part of Tottori-city died within the period of 40 days of summer in 1989. Seven of 8 Mute swans were pathologically examined. In all swans many yellowish-brown to greenish-brown granules were found in the cytoplasm of hepatocytes. The granules were intensely stained with rhodanine copper stain, schmorl method, and Berlin blue stain. Ultrastructurally, many lysosomes increased in size and density in the cytoplasm of hepatocytes. Other three swans, that died at other places, were served as controls. In control swans, many brown granules intensely stained with schmorl method and Berlin blue stain were also found in hepatocytes, but the number of rhodanine-positive granules were fewer than those of the affected cases. X-ray qualitative analysis showed three peaks corresponding to copper, zinc and sodium in the liver of the affected and control swans. Quantitative analysis demonstrated that mean hepatic copper concentration of the affected group was significantly higher than that of control group (P less than 0.01). From these findings, we concluded that all of 7 Mute swans died of copper poisoning.     

Mode of action of nereistoxin on the neuromuscular transmission in the frog

The effects of nereistoxin on the neuromuscular transmission of the frog have been studied by means of intracellular microelectrode and voltage clamp techniques. Nereistoxin blocked the neuromuscular transmission without causing depolarization of end-plate membranes. A small end-plate potential was elicited upon nerve stimulation. The frequency and amplitude of miniature end-plate potentials decreased after exposure to nereistoxin, and the quantum content of the end-plate potential tended to decrease also. Chemical sensitivity of the end-plate membrane as examined by iontophoretic application of acetylcholine was markedly reduced. Both sodium and potassium components of the end-plate current were suppressed almost equally by application of nereistoxin. It is concluded that inhibition of the mechanisms whereby the end-plate membrane conductances to sodium and potassium ions are increased is the major action of nereistoxin responsible for neuromuscular blockade.     

Genome-wide mapping and identification of new quantitative trait loci affecting meat production, meat quality, and carcass traits within a Duroc purebred population

Most QTL detection studies in pigs have been carried out in experimental F(2) populations. However, segregation of a QTL must be confirmed within a purebred population for successful implementation of marker-assisted selection. Previously, QTL for meat quality and carcass traits were detected on SSC 7 in a Duroc purebred population. The objectives of the present study were to carry out a whole-genome QTL analysis (except for SSC 7) for meat production, meat quality, and carcass traits and to confirm the presence of segregating QTL in a Duroc purebred population. One thousand and four Duroc pigs were studied from base to seventh generation; the pigs comprised 1 closed population of a complex multigenerational pedigree such that all individuals were related. The pigs were evaluated for 6 growth traits, 7 body size traits, 8 carcass traits, 2 physiological traits, and 11 meat quality traits, and the number of pigs with phenotypes ranged from 421 to 953. A total of 119 markers were genotyped and then used for QTL analysis. We utilized a pedigree-based, multipoint variance components approach to test for linkage between QTL and the phenotypic values using a maximum likelihood method; the logarithm of odds score and QTL genotypic heritability were estimated. A total of 42 QTL with suggestive linkages and 3 QTL with significant linkages for 26 traits were detected. These included selection traits such as daily BW gain, backfat thickness, loin eye muscle area, and intramuscular fat content as well as correlated traits such as body size and meat quality traits. The present study disclosed QTL affecting growth, body size, and carcass, physiological, and meat quality traits in a Duroc purebred population.