Analyses of leaves from open field-grown transgenic poplars overexpressing xyloglucanase

The transgenic expression of Aspergillus xyloglucanase cDNA (AaXEG2) with 35S promoter in the leaves of open field-grown poplars was studied. The level of xyloglucan in the transgenic poplars was decreased to 15–16% in the non-fertile soil (forest-field soil) and to 21–22% in the fertile soil (farming-field soil) compared with that of the wild-type poplars. The leaves exhibited a smaller surface area with more rounded teeth than those of the wild-type plants, similar to the sun leaf variety that was grown in the incubation room and subsequently greenhoused. The majority of total veins with water-conducting vascular bundles were shorter in the leaves of the transgenic poplars than those of the wild type. This decrease in vein length may result from a decrease in xyloglucan during leaf development, from which large numbers of proteins were markedly downregulated in the leaves of the transgenic plants via proteomic analysis. It seems likely that the leaves of the transgenic poplars came to relax the edges of their tooth rather than extend their veins as a result of the loosening of the xyloglucan cellulose networks in the leaves.     

Pigment pattern formation by contact-dependent depolarization

Although recent experimental studies have suggested that the interactions among the pigment cells play a key role in the skin pattern formation, details of the mechanism remain largely unknown. By using an in vitro cell culture system, we have detected interactions between the two pigment cell types, melanophores and xanthophores, in the zebrafish skin. During primary culture, the melanophore membrane transiently depolarizes when contacted with the dendrites of a xanthophore. This depolarization triggers melanophore migration to avoid further contact with the xanthophores. Cell depolarization and repulsive movement were not observed in pigment cells with the jaguar mutant, which shows defective segregation of melanophores and xanthophores. The depolarization-repulsion of wild-type pigment cells may explain the pigment cell behaviors generating the stripe pattern of zebrafish.     

Interspecies transmission of equine influenza virus (H3N8) to dogs by close contact with experimentally infected horses

In horse populations, influenza A virus subtype H3N8 (equine influenza virus, EIV) is a very important pathogen that leads to acute respiratory disease. Recently, EIV has emerged in dogs, and has become widespread among the canine population in the United States. The interspecies transmission route had thus far remained unclear. Here, we tested whether the interspecies transmission of EIV to dogs could occur as a result of close contact with experimentally EIV-infected horses. Three pairs consisting of an EIV-infected horse and a healthy dog were kept together in individual stalls for 15 consecutive days. A subsequent hemagglutination inhibition test revealed that all three dogs exhibited seroconversion. Moreover, two of the three dogs exhibited virus shedding. However, the dogs exhibited no clinical signs throughout the course of the study. These data suggest that the interspecies transmission of EIV to dogs could occur as a result of close contact with EIV-infected horses without clinical symptoms. Although the interspecies transmission of EIV is unlikely to become an immediate threat to canine hygiene, close contact between EIV-infected horses and dogs should be avoided during an EI epidemic.     

Streptococcus equi but not Streptococcus zooepidemicus produces potent mitogenic responses from equine peripheral blood mononuclear cells

Streptococcus equi causes equine strangles. The acute disease has many of the hallmarks of an acute response including high fever, elevated plasma fibrinogen and neutrophilia, affects known to be mediated by proinflammatory cytokines. The objective of this study was to screen-culture supernatants from equine clinical isolates of S. equi and S. zooepidemicus for stimulation of mitogenic responses by horse peripheral blood mononuclear cells. Mitogenicity comparable to that of concanavalin A was detected in culture supernatants of S. equi strains but not in those of S. zooepidemicus. Mitogenicity was neutralised by Proteinase K and a post-strangles convalescent serum, and evidence for the presence of both thermo-resistant and thermo-labile mitogenic factors was obtained. Release of proteinaceous immunogenic mitogens in combination with the antiphagocytic protein SeM unique to S. equi may therefore contribute to some of the severe clinical manifestations of acute strangles in the horse.     

Comparison of the effects of isotonic and hypertonic sodium bicarbonate solutions on acidemic calves experimentally induced by ammonium chloride administration

The objectives of this study were to evaluate and compare the effects of intravenously (IV) administered infusion of isotonic solution (ISB) or hypertonic sodium bicarbonate solution (HSB) on acid-base equilibrium and the plasma osmolarity in acidemic calves experimentally induced by 5 M-NH(4)Cl, IV infusion (1.0 ml/kg, over 1 hr). The ISB and HSB infusion induced progressive and significant increases in their HCO(3)(-) and BE levels that persisted throughout the period of fluid administration. The plasma osmolarity in the ISB groups was significantly decreased. The plasma osmolarity in the HSB group was significantly higher than in the calves in the other groups (p<0.05). ISB solution might be safe and effective for treating and reviving conscious calves from experimentally induced metabolic acidosis.     

Pressure-flow relationship and longitudinal distribution of pulmonary vascular resistance in heartworm-infected dogs

The pressure-flow relationships and the longitudinal distributions of pulmonary vascular resistance in normal and heartworm-infected (HWI) dogs were compared in an isolated, blood perfused preparation. The pulmonary circulation was partitioned into pulmonary arterial, middle, and venous segment based on the concept of a five element lumped model. The pulmonary arterial pressure-flow relationships were found to be non-linear and convex to the pressure axis in both normal and HWI lungs. The pressure-flow relationships of the pulmonary arterial and venous segment were linear and these slopes in the HWI lungs were significantly higher than the normal lungs. The pressure gradient of the middle segment was increased as flow increased at lower flow range, however, it was not increased during higher perfusion range in both lungs. At higher flow, the pressure gradient of the middle segment in the HWI lungs was significantly higher than the normal lungs. These results suggest that the ohmic resistance was almost equal to the sum of the two slopes of the pressure-flow relationships of the pulmonary arterial and venous segment because the pressure gradient of the middle segment was not altered as flow increased during higher perfusion rate. Because the slopes of the pressure-flow relationships of the pulmonary arterial and venous segment were increased with heartworm infection, the ohmic resistance of HWI lungs would be higher than normal lungs. The intercept pressure on the pressure axis of the linear portion of the pulmonary arterial pressure-flow relationship, a critical closing pressure, was regarded as pressure gradient of the middle segment during higher perfusing rate because the intercept pressures of pressure-flow relationships of pulmonary arterial and venous segment were almost equal to zero. Therefore, the critical closing pressure of HWI lungs would be higher than normal lungs. The pulmonary hypertension of filariasis appears to be due to an increase in ohmic resistance and elevated critical closing pressure.     

Characterization of some Asian isolates of Phytophthora infestans

A total of 401 isolates of Phytophthora infestans were collected from eight Asian regions (Korea, India, Taiwan, Indonesia, Thailand, Nepal, China and Japan) between 1992 and 2000 – 318 from potato and 83 from tomato. The isolates were analysed for mating type, metalaxyl resistance, RG57 fingerprinting, mitochondrial DNA (mtDNA) haplotype and the polymorphism of three allozyme loci, i.e. glucose-6-phosphate isomerase ( Gpi ), peptidase ( Pep ) and malic enzyme ( Me ). The isolates were multilocus-genotyped based on RFLP (RG57) fingerprint, dilocus allozyme genotype, mtDNA haplotype and mating type. Twenty multilocus genotypes were identified among 125 isolates. Of these genotypes, 14 had not been previously reported. Some of the multilocus genotypes were common to isolates from several geographical regions, suggesting migration. The metalaxyl-resistant isolates belonged to the multilocus genotypes JP-1, JP-2, and JP-3. Multilocus genotypes coexisting in a single field were found in following regions: Thailand (1994), central China (1996), Nepal (1997) and Japan (1998 and 2000). The possible origins of certain genotypes are discussed, including the possibility of sexual recombination within the P. infestans populations in Nepal and perhaps Thailand.     

Determination of bisphenol A in canned pet foods

Bisphenol A (BPA) contamination of canned foods for human use has been studied, but there are no reports concerning BPA contamination of canned pet foods. The purpose of this study was to identify the levels of BPA in canned pet foods. A total of 26 samples (15 samples of cat food and 11 samples of dog food) were prepared for analysis by high-performance liquid chromatography. BPA in the samples was extracted with acetonitrile and fat in the sample extract was removed with hexane. Solid-phase extraction was used for sample clean-up prior to final analysis. The concentration of BPA ranged from 13 to 136 ng/g in canned cat food and from 11 to 206 ng/g in dog food. Also, to confirm that the BPA had originated from the can coating, distilled water was added to each washed empty can and the cans were autoclaved at 121 degrees C for 30 min. The concentration of BPA leached from empty cans was between 7 and 31 ng/ml.