Evaluation of Salmonella enterica serovar Typhimurium and Choleraesuis slyA mutant strains for use in live attenuated oral vaccines

SlyA protein plays a key role in virulence in Salmonella enterica. In this study, we evaluated the ability of the slyA mutant strain of S. enterica serovar Choleraesuis (S. choleraesuis) to protect against swine salmonellosis. Using a murine model infected with S. enterica serovar Typhimurium (S. typhimurium), we showed that the Salmonella strain with a deletion of slyA could be used as a highly immunogenic, effective and safe vaccine in mice. Based on these data, a slyA mutant of S. enterica serovar Choleraesuis strain RF-1 was constructed, and the ability of this mutant to protect immunized pigs from S. choleraesuis infection was examined. As with the S. typhimurium slyA mutant, immunization of pigs with the S. choleraesuis slyA mutant strain provided significant protection against subsequent challenge by the wild-type RF-1. These results demonstrate that SlyA is a potential target in the development of a novel live attenuated vaccine against S. enterica.     

The characterization of low pathogenic avian influenza viruses isolated from wild birds in northern Vietnam from 2006 to 2009

Due to concerns that wild birds could possibly spread H5N1 viruses, surveillance was conducted to monitor the types of avian influenza viruses circulating among the wild birds migrating to or inhabiting in northern Vietnam from 2006 to 2009. An H5N2 virus isolated from a Eurasian woodcock had a close phylogenetic relationship to H5 viruses recently isolated in South Korea and Japan, suggesting that H5N2 has been shared between Vietnam, South Korea, and Japan. An H9N2 virus isolated from a Chinese Hwamei was closely related to two H9N2 viruses that were isolated from humans in Hong Kong in 2009, suggesting that an H9N2 strain relevant to the human isolates had been transmitted to and maintained among the wild bird population in Vietnam and South China. The results support the idea that wild bird species play a significant role in the spread and maintenance of avian influenza and that this also occurs in Vietnam.     

Leaf mold of tomato caused by races 4 and 4.11 of Passalora fulva in Japan

Leaf mold of tomato was found on cv. Momotaro-fight in 2003 in Ehime Prefecture. The symptoms were marginal indefinite yellowing on the upper leaf surface, and downy, gray to brown sporulation on the lower surface underneath the spots. The symptoms and morphology were the same as seen with Passalora fulva. The fungal isolates were identified as races 2.4, 2.4.11, 4, and 4.11 by inoculation tests. Races 4 and 4.11 have never before been found in Japan.     

Response of enzyme activities and metabolic intermediate concentrations to a long burst of exercise and following resting in muscle and the hepatopancreas of carp

ABSTRACT: The responses of enzyme activities and metabolic intermediate concentrations to a long burst of exercise and following resting were examined in muscle and the hepatopancreas of carp Cyprinus carpio . A 15 min burst of exercise made the fish so exhausted that they could not swim any more. In muscle, the exercise decreased glycogen content significantly and increased lactate content significantly, resulting in a lowered pH. Furthermore, the burst of exercise decreased phosphofructokinase (PFK) activity significantly, although it changed adenosine-5'-monophosphate, adenosine-5'-diphosphate, adenosine-5'-triphosphate, fructose-6-phosphate and citrate concentrations within ranges that could activate PFK. In the hepatopancreas, the exercise increased glucose-6-phosphatase and fructose-1,6-bis-phosphatase activities, and glucose and lactate concentrations in the serum, and it decreased glycogen content. Even at 3 h resting after the burst of exercise, the fish had not completely restored many parameters. These results suggest that although the fish tried to enhance in vivo muscular glycolysis through the activation of PFK by changes in metabolic intermediate concentrations, glycolysis seemed to decrease markedly through the inhibition of PFK as a result of the lowered pH. However, the hepatopancreas made a contribution to muscular exercise through glucose supplementation by enhanced gluconeogenesis and glycogenolysis, indicating the presence of an interdependence of carbohydrate metabolism between muscle and the hepatopancreas in the fish.     

Alteration of release and role of adenosine diphosphate and thromboxane A2 during collagen-induced aggregation of platelets from cattle with Chediak-Higashi syndrome

OBJECTIVE: To compare the interaction of endogenous ADP with collagen and thromboxane A(2) (TXA(2)) during collagen-induced platelet aggregation between platelets from healthy cattle and those with Chediak-Higashi syndrome (CHS). POPULATION SAMPLE: Platelets harvested from blood samples from healthy Japanese Black cattle and those with CHS. PROCEDURES: Aggregation of gel-filtered platelets; release of ATP-ADP; and generation of thromboxane B(2) (TXB(2)), a metabolite of TXA(2), were measured. RESULTS: The potency of collagen to induce aggregation in platelets of cattle with CHS (ie, CHS platelets) was less than a tenth of that in platelets of healthy cattle (ie, control platelets). Platelet aggregation induced by collagen at an intermediate concentration depended on the coexistence of ADP and TXA(2), suggesting that released ADP cannot cause platelet aggregation by itself. Collagen-induced ADP release was markedly decreased, whereas TXB(2) production was slightly low in CHS platelets, compared with that in control platelets. A combination of subthreshold amounts of ADP and 9,11-dideoxy-9alpha, 11alpha-methano-epoxy-prostaglandin F(2) (U46619), a TXA(2) analogue, caused platelet aggregation. Similarly, a combination of subthreshold amounts of collagen and ADP caused platelet aggregation, whereas collagen and U46619 were not synergistic. CONCLUSIONS AND CLINICAL RELEVANCE: Deficient ADP release ensuing from the delta-storage pool deficiency in platelets from cattle with CHS resulted in reduction of collagen-induced platelet aggregation, through attenuation of synergism between TXA(2) and ADP and between ADP and collagen. Furthermore, results of the study reported here indicated that TXA(2) was important for aggregation of bovine platelets.     

Concentrations of ketone body and antidiuretic hormone in cerebrospinal fluid in response to the intra‐ruminal administration of butyrate in suckling calves

The aim of the present study was to elucidate the mechanism by which ketone bodies increase antidiuretic hormone (ADH) secretion. Four male Holstein calves (5 weeks of age) were utilized. Four levels of butyrate (0 g, 11 g, 22 g and 44 g) were administrated intra‐ruminally in a 4 × 4 Latin square design and cerebrospinal fluid (CSF, six‐position lumbar puncture), blood plasma and urine were collected. The concentration of total plasma and CSF protein was 5.5–5.6 g/dL and 27.5–28.3 mg/dL, respectively. CSF concentrations of a specific ketone body, 3‐hydroxybutyric acid, were significantly higher in the 22 g and 44 g butyrate groups than in the control group. CSF concentrations of ADH in the 11 g and 44 g butyrate groups were significantly higher than in the control group. Plasma concentration of 3‐hydroxybutyric acid was increased by intraruminal administration of butyrate within 15 min in a dose‐dependent manner, and it was higher in the 22 g and 44 g butyrate group than in the control group from 15 min to 4 h. With the exception of the 11 g butyrate group, plasma concentrations of ADH also increased in response to butyrate treatment, and it was higher in the 44 g butyrate group than in the 22 g butyrate group from 15 min to 1.5 h. The duration of the elevated plasma concentrations of ADH was shorter than that of the plasma concentration of 3‐hydroxybutyric acid. The relationship between the plasma concentrations of ADH and 3‐hydroxybutyric acid was statistically significant but the correlation between the two concentrations was not high. Butyrate treatment elevated the plasma concentration of ADH and also resulted in reduced urine volume and increased urine osmolality. Haematocrit (Ht) values, and the osmolality of CSF and plasma were not different among the groups. Our results suggested that the increased ADH secretion observed in suckling calves fed dry feeds was caused by butyrate‐derived ketone body that crossed the blood‐brain barrier rapidly.     

Assessment of phosphorus bioavailability in cultivated Andisols from a long-term fertilization field experiment using chemical extractions and soil enzyme activities

Various chemical extraction methods have been used to evaluate soil phosphorus (P) availability in different ways, and therefore inconsistent results are often obtained. This study examined the usefulness of the resource allocation model for extracellular enzymes for evaluating P availability in soils from a more biological perspective. Potential P availability was evaluated using the Truog and Bray-2 tests, the Hedley sequential extraction procedure, and enzyme activity assessments in cultivated Andisols from a 70-year-old fertilization experiment. Both the ratio of acid phosphatase to β-D-glucosidase activities and the ratio of alkaline phosphatase to β-D-glucosidase activities showed significant negative correlations with potentially available inorganic P, suggesting that microorganisms preferentially expended resources in the form of phosphatase production rather than β-D-glucosidase production to acquire P. Additionally, crop P content had a significant negative relationship to the ratio of alkaline phosphatase to β-D-glucosidase activities. These results suggest that the resource allocation model for extracellular enzymes is useful for evaluating P availability in Andisols.     

Long-term changes in the chemical properties of Japanese cedar (Cryptomeria japonica) forest soils under high precipitation in southwest Japan

There is insufficient direct evidence of long-term changes in the chemical properties of forest soils to provide information for forestry management plans for sustainable site productivity. To understand changes in the chemical properties of forest soils in a specific high-precipitation climate in Japan, we re-investigated, in 1997, soil pits within a Japanese cedar (Cryptomeria japonica) forest in the Yanase region of Kochi Prefecture which had previously been surveyed in 1976. Comparison of the 1976 and 1997 results revealed significantly lower pH of surface and subsurface soils, and fewer exchangeable cations over time. In contrast, subsoil pH, concentrations of total carbon and nitrogen, and cation-exchange capacity (CEC) had not changed over the 21-year period. Estimation of proton and cation budgets in the forest ecosystem over 21 years, using data for the amounts in soil, biomass accumulation, and input through precipitation, revealed that biomass accumulation did not explain the cation depletion in soils. This suggests that cations were leached from the ecosystem. In contrast with previous reports, which showed Ca accumulation in Japanese cedar forest soils, our results indicated that high precipitation of more than 4,000 mm combined with acid deposition resulted in soil acidification and leaching of cations from soils, following the decrease in base saturation.