Enteropathogenicity of Dutch and German avian reoviruses in SPF white leghorn chickens and broilers

The enteropathogenicity of avian reoviruses (ARVs), isolated from chickens affected with malabsorption syndrome (MAS) from The Netherlands and Germany was studied. In the first trial seven different ARVs isolated from MAS cases were inoculated in 1-day-old specific pathogenic free (SPF) white leghorns. The pathogenicity was compared with 2 ARVs isolated from cases of tenosynovitis, namely reference strain S1133 and a Dutch strain. Although a difference in the severity of the clinical disease was observed, all reoviruses could induce vacuolar degeneration and sloughing of the epithelium of the small intestine at day 2 post inoculation (PI) till day 7 PI. Two Dutch and one German ARV derived from MAS causing the most severe intestinal lesions at day 2 PI, were further studied in the second trial using SPF broilers. These reoviruses did not cause weight gain depression in the broilers although lesions in the small intestine were present from day 1 up to day 4 PI and were more severe than in the white leghorn chickens. In one of the inoculated groups apical denuded villi were already present at day 1 PI. At day 7 PI the small intestine of the infected broilers appeared to be normal. Reovirus antigen was detected in the cytoplasm of the enterocytes at the tip and middle section of the affected villi both in layers and in broilers. To study the role of intestinal CD4+ and CD8+ T-cells and macrophages/monocytes in the pathogenesis of ARV, the numbers of these cells of the jejunal villi of one infected and the control broiler groups were compared. CD4+ T-cells were detected in low numbers and only in the infected broiler group at day 14 PI. The numbers of CD8+ T-cells and macrophages/monocytes were significantly higher in the infected broiler group than in the control broiler group at day 7 and 14 PI and at day 7 PI respectively. Our study indicates that the reovirus alone cannot induce intestinal lesions as found in MAS chickens. Moreover, CD8+ T-cells may play a major role in the pathogenesis and or reovirus clearance in the small intestine.     

The absence of Rhodococcus equi in Mongolian horses

In native Mongolian horses, the incidence and distribution of Rhodococcus equi are poorly understood. One hundred and fourteen equine fecal samples and 71 soil samples were collected from the camp sites of 26 nomadic families located in three areas less than 100 km from Ulaanbaatar, Mongolia. Five fecal samples were also collected from foals of Przewalski's Horses introduced into the Hustai National Park, Mongolia. No R. equi was isolated from the Mongolian horses or the soil samples. However, three colonies of R. equi were isolated from two fecal samples collected from foals of Przewalski's Horses. These isolates were avirulent, with neither 15- to 17-kDa antigens (VapA) nor a 20-kDa antigen (VapB) genes being detected. We concluded that native Mongolian horses and their environment appear free from contamination with R. equi.     

Perfusion analysis of periportal and centrilobular metabolism of paraoxon in the rat liver

Paraoxon infused into the rat liver during perfusion in situ with Waymouth's medium underwent chromatographic translobular migration with an apparent hepatic transit time of 3 min. Intralobular heterogeneity of paraoxon metabolism was examined by analyzing metabolites produced under conditions minimizing the chromatographic translobular migration of paraoxon. Periportal and centrilobular activities were estimated following forward and retrograde infusion of paraoxon, respectively. Centrilobular hepatocytes exhibited nearly twice the metabolic rate of the periportal cells. Pretreatment of the rat with DDE resulted in about a threefold increase in the ratio of oxidative deethylation to hydrolytic dearylation in the centrilobular region. The differentials observed by these analyses were less pronounced than expected from enzyme analyses in vitro, possibly reflecting secondary metabolism or intracellular heterogeneity of metabolic activities.     

The degradation of diflubenzuron and its chief metabolites in soils. Part I: Hydrolytic cleavage of diflubenzuron

[¹⁴C]Diflubenzuron is readily degraded in various agricultural soils and in hydro-soil; 50% of the applied dose of 1 mg kg⁻¹ was metabolised in 2 days or less. The chief products of hydrolysis were identified as 4-chlorophenylurea and 2, 6-difluorobenzoic acid. A part of the radioactivity, increasing with incubation time, could not be extracted. Release from the soil of [¹⁴C]carbon dioxide, derived from both labelled phenyl rings, points to the ultimate mineralisation of diflubenzuron.     

Rat liver paraoxonase (paraoxon arylesterase)

Paraoxonase in the liver of male Sprague-Dawley rats was studied by using [phenyl-1-¹⁴C]paraoxon. Examination of the enzyme activity in subcellular fractions of liver homogenates indicated that hepatic paraoxonase is essentially a microsomal enzyme with a pH optimum of 7.5 to 7.8. Effects of calcium ions and EDTA on the enzyme suggested that active paraoxonase is a protein-calcium complex possibly with a range of affinity to calcium ion. Activity in homogenates declined with a half-life of 6 to 9 hr when stored at 0°C, apparently reflecting dissociation of calcium ions. Experiments with homogenates of perfused liver provided evidence that even without the contribution of calcium from blood, paraoxonase is almost fully active at the moment of homogenization. Possible reasons for the much reduced activity of paraoxonase in in vivo metabolism are discussed.     

A case study of infection of rice roots by deleterious fungi and minor pathogenic<Emphasis Type="Italic"> Pythium</Emphasis> species in a paddy field

Roots of rice plants grown in paddy fields in a transplant culture system were collected seven times between 8 and 22 weeks after transplanting, for two crop seasons. Rice seedlings grown in a potting medium amended with the collected roots were significantly shorter than those grown in the same medium either without the addition of the roots or amended with pasteurized, collected roots indicating that seedlings were inhibited by heat-labile microorganisms on the collected rice roots. Ninety-five and 172 pure cultures of Pythium spp. and fungi, respectively, were isolated from the rice roots collected 5 or 7.5 weeks after transplanting in the fields. Among these microorganisms, Pythium aristosporum inhibited seedling growth in greenhouse experiments, and Acremonium sp., Alternaria sp., Epicoccum nigrum, Fusarium sp., Massarina sp., Penicillium spp., Rhinocladiella sp., Stemphylium sp., Trichocladium sp., and several unidentified fungi inhibited seminal root growth in in vitro experiments. These microorganisms might be involved in the inhibition of seedling growth in soils amended with the rice roots collected from the paddy field. Thus, roots of rice plants at the middle stage of growth transplanted into paddy fields can harbor pathogenic or deleterious fungi or Pythium sp(p). The effects of these microorganisms on rice growth in paddy fields are discussed.     

Urinary excretion of purine derivatives and plasma allantoin level in sheep and goats during fasting

The relationship between blood plasma level and urinary excretion of allantoin (AN) was examined in sheep and goats during fasting to investigate the possible use of purine derivatives (PD) in urine and/or plasma for estimating the microbial protein production in the rumen, and the further digestion in the lower guts of ruminants. Urinary AN excretion decreased markedly during fasting (0.13 mmol/kgW^0.75 per day), although urinary levels of other PD, hypoxanthine + xanthine and uric acid did not differ irrespective of the feeding condition, that is, feeding, fasting and refeeding in both species. The AN concentration in blood plasma also decreased drastically in the starvation period, and was suddenly increased on refeeding in sheep and goats, and these phenomena were very similar to those of urinary AN excretion. Therefore, there was a high positive correlation between plasma AN level and urinary AN excretion, and the coefficient of correlation was statistically significant (P < 0.01). These results clearly indicate that changes in urinary AN reflect change in plasma AN, which is induced by the catabolism of purine base in the body.     

Effect of theanine, γ-glutamylethylamide, on bodyweight and fat accumulation in mice

To clarify the details of the anti‐obesity effect of theanine, γ‐glutamylethylamide, female ICR mice were fed diets containing theanine at the concentrations of 0.01, 0.02, 0.04, 0.08 and 0.16% for 16 weeks. Bodyweight and food intake in the mice were measured every 4 weeks, and several organs and intraperitoneal adipose tissues (IPAT) were weighed after the feeding. In addition, lipid levels in the serum and liver were analyzed. As a result, the bodyweight increase and weight of IPAT were significantly reduced in mice fed 0.04% theanine compared with controls, but not in mice fed other diets. The levels of triglycerides (TG) and non‐esterified fatty acids in the serum and TG level in the liver in mice fed the 0.04% theanine diet were remarkably decreased. These results indicated that bodyweight increase and fat accumulation were suppressed by a limited concentration of 0.04% theanine in mice.     

Relationship between fat accumulation in the liver and energy intake, milk fat yield and blood metabolites in dairy cows

In the present study, 42 multiparous Holstein cows were used to investigate the relationship between fat accumulation in the liver and dry matter intake, milk yield and blood metabolites. Based on the percentage of fat in the liver cell at 2 weeks post‐parturition, the cows were classified into three groups. These groups were: (i) less than 10% of fat (normal group, n = 29); (ii) 10–20% of fat (mild group, n = 6); and (iii) more than 20% of fat (moderate group, n = 7). The bodyweight of the moderate group was high (771 kg) before calving. The sufficiency rates of total digestible nutrients (TDN) were remarkably decreased (approximately 65%) in early lactation. The milk fat yield and milk fat composition of the moderate group were higher (P < 0.05) than the other groups at 1 and 2 weeks post‐parturition. It was suggested that non‐esterified fatty acids (NEFA) mobilized from adipose tissues was directly used by the mammary gland for synthesis of milk fat. The percentage of bromsulfalein (BSP) retention of the moderate group was high (21.1%) at 30 min, and it showed that the BSP clearance function was significantly decreased. The concentrations of NEFA, β‐hydroxybutyric acid and glucose were appropriate indicators of energy status; however, aspartate aminotransferase, γ‐glutamyl transpeptidase and total bilirubin were not sensitive indicators of a moderate fatty liver. Thus, high‐yielding cows that calve in an overweight condition are more likely to develop excessive fat accumulation in the liver because of great mobilization from adipose tissues post‐parturition. In cows with a moderately fatty liver, a decrease in TDN sufficiency rates, an increase of milk fat yield and a reduction of liver function were observed in early lactation. The increase of serum NEFA and milk fat composition resulting from mobilization of adipose tissues helped to diagnose moderate fatty liver.     

Role of SraP in adherence of Staphylococcus aureus to the bovine mammary epithelia

SraP, a platelet-binding surface protein of Staphylococcus aureus, is involved in the pathogenesis of infective endocarditis. In this study, we investigated the importance of SraP in the pathogenesis of bovine mastitis. By means of PCR, sraP was detected in all the isolates tested from bovine bulk milk and humans. However, SraP was not expressed on the cell surface in half of the bovine isolates. Moreover, disruption of sraP did not affect the ability of S. aureus to adhere to cultured bovine mammary epithelial cells. These results suggest that SraP does not seem to be an important factor for S. aureus to adhere to the bovine mammary epithelia.