Safety of the tram car for slopes examined by stress analysis of the ground structure

For monorail systems, it is very important to ensure the safety of the ground structure. We developed a tram car for slopes that utilizes the mechanism of the monorail and analyzed the stress of the ground structure that had double rails. First, we divided the ground structure into seven components, and formulated a procedure for calculating the stress of the ground structure. As a result, the stress that acts upon the main rail and the main rail connecting part was near the allowable stress, and each calculated value was within the allowable stress. We measured the stress by running the vehicle, and compared the measured values with the calculated values. As a result, some measured values were larger than the calculated values. However, the ratio of measured value to allowable stress was 90% or less. Finally, we calculated the static loading coefficient for each part, results of which were as follows: main and subrail: 1.1; rail connection part and prop foundation part: 1.0; rail installation part: 1.3. In the recalculations, it became clear that the recalculated values exceeded the allowable stresses. These results suggest that we need to review the ground structure materials.     

Detection of antibodies against Pasteurella multocida using immunohistochemical staining in an outbreak of rabbit pasteurellosis

To detect serum antibody against Pasteurella multocida (P. multocida) in infected rabbits. a modified immunoperoxidase assay was applied. An outbreak of P. multocida infection in rabbits started from sudden death. The infected rabbits had severe fibrinous and purulent pneumonia with hemorrhage, and a large number of P. multocida (A:12) was isolated from the trachea and lungs of the animals. Antibodies of IgM and IgG to P. multocida were assessed by immunohistochemical staining using the sera of the animals as primary antibodies and applying them to formalin-fixed, paraffin-embedded sections of P. multocida attached to calf fibrin. IgM antibodies to P. multocida were first detected 7 days after the onset of the disease. IgG antibodies began to rise on the 7th or 14th day. These results suggested that the modified immunoperoxidase assay could detect antibodies against P. multocida.     

Molecular epidemiological survey of benign Theileria parasites of cattle in Japan: detection of a new type of major piroplasm surface protein gene

Benign Theileria species of cattle are found in most parts of the world. The major piroplasm surface protein (MPSP), a conserved protein in all Theileria species, has been used as a maker for epidemiological and phylogenetical studies of benign Theileria species. Parasites with Ikeda- or Chitose-type MPSP genes are dominant in Japan, but we report here mixed infection cases of Theileria parasites with an additional MPSP type parasite infecting cattle in Abashiri District, Hokkaido. The MPSP gene sequence found in the additional type was closely related to MPSP genes of Theileria parasites found in Southeast Asian countries, including Thailand (Narathiwat) and Indonesia (Java). Theileria parasites from the blood sample were also distinguishable from the Ikeda or Chitose type parasites by the small subunit (SSU) rRNA gene sequence analysis, and they are grouped into the SSU rRNA types C/D found in Korea, North America, and Spain. The present finding of mixed infections of cattle with three different types of Theileria makes epidemiological feature of bovine theileriosis in Japan more complex. We have designed a set of primers specific to this MPSP type in order to conduct further epidemiological study.     

Isolation of Pathogenicity Mutants of Fusarium oxysporum f. sp. melonis by Insertional Mutagenesis

Restriction enzyme-mediated integration (REMI) mutagenesis was used to isolate mutants of Fusarium oxysporum f. sp. melonis impaired in pathogenicity. The race 2 strain Mel02010 was transformed with linearized pSH75, conferring resistance to hygromycin B, with or without the enzyme used to linearize the plasmid. Addition of restriction enzymes did not affect the transformation frequency. A total of 2929 REMI transformants were tested for pathogenicity to three melon cultivars, Amus, Ogon 9 and Ohi. The race 2 strains are pathogenic to Amus and Ogon 9, but not to Ohi. Of 43 transformants with reduced pathogenicity on susceptible melon cultivars, 12 mutants were examined in detail for pathogenicity, vegetative growth and integrative mode of pSH75. The levels of pathogenicity varied among these mutants. Two mutants (B48 and B137) almost completely lost pathogenicity to both susceptible cultivars, and the others had reduced pathogenicity. Mutants B48, B241, B886 and X36 were also impaired in vegetative growth. Mutant B809 was a biotin auxotroph. By DNA gel blot analysis, nine mutants were found to contain a single copy of the transformation vector. These mutants may thus be useful in isolating genes involved in pathogenicity. Received 22 December 2000/ Accepted in revised form 16 April 2001     

Nitrous oxide emission measurement with acetylene inhibition method in paddy fields under flood conditions

Nitrous oxide (N₂O) emission from flooded rice paddy fields was continuously measured by the closed chamber method at an experimental plot in Thailand for a whole cultivation period. To characterize the N₂O emission with regard to the denitrification N loss, the C₂H₂ inhibition method was applied. Flood water on the soil greatly suppressed the N₂O emission. The N₂O emission was mitigated considerably by even a thin film of the flood water. The overall average N₂O emissions under flood conditions for one crop season (83 days) at the control site and the C₂H₂ treated site were 10.3 and 11.8 μg N m⁻² h⁻¹, respectively. The N₂O emission from the C₂H₂ treated site was consistently higher than that from the control site and the N₂O emission from both sites followed the same diurnal and seasonal variation pattern, indicating the effect of denitrification inhibition by the supplied C₂H₂. The N₂O emission enhanced along with temperature increase when NO₃–N concentration in the soil water was above 0.4 mg N l⁻¹ and soil temperature was above 24°C, suggesting specific temperature influence over the emission. The increase in NO₃–N concentration and temperature in the soil affected only the N₂O emission while the difference in the emission at the C₂H₂ treated site and the control site was not so much affected. It was suggested that most of the actively produced N₂O under higher NO₃–N concentration and temperature would likely to quickly emit to the atmosphere rather than to undergo further reduction to N₂.     

Extractive components and taste aspects of fermented fish pastes and bean pastes prepared using different koji molds as starters

We have evaluated four commercially available mold starters (SP-01, NY, M1, and “for kome miso”) for fermented fish pastes with the aim of determining the effect of different koji molds on the nutritional and sensory characteristics of the fermented product. Comparative studies among different fermented fish and bean pastes were also conducted. Protein contents were considerably higher in the fermented fish pastes (22.7–24.1%) than the fermented bean pastes (8.2–12.8%). Free amino acids, oligopeptides, organic acids, mineral content, and sensory scores of the fermented fish pastes were superior to those of the bean pastes in terms of nutritional aspects. Sensory evaluation of fermented fish and bean pastes clearly indicated that different koji molds used as starters had little effect on the taste of the fermented fish pastes. However, in terms of nutritional and sensory characteristics, fermented fish pastes from trash fishes were found to be both commercially valuable and a potential gain to food processing firms among the many new generic fermented food products becoming available.     

Relationships between body size and secondary sexual characters,and sperm characters in male Dolly Varden char (Salvelinus malma)

In Salmonidae, subordinate males are exposed to higher risks of sperm competition than dominant males and thus are expected to improve the sperm characteristics (sperm concentrations, sperm velocity and sperm longevity). In this study, we investigated the relationships between body size and secondary sexual characters (breeding colour, hump height and snout length), and sperm characteristics of one‐year‐old (newly matured) Dolly Varden char. Small males displayed higher sperm concentrations than large males. Moreover, males with dull breeding colours, but not with lesser snout length and hump height, displayed an increased sperm velocity compared to males with bright colours, suggesting a trade‐off between sperm quantity and the investment in breeding colour. In addition, sperm longevity decreased as sperm swimming velocity increased. These findings indicate that small males with dull breeding colours improve the quantity and quality of their sperm to a great extent to enhance their chances of reproductive success.