Competitive enzyme-linked immunosorbent assay for the detection of the antibodies specific to akabane virus.

A competitive enzyme-linked immunosorbent assay (C-ELISA) using neutralizing monoclonal antibodies (MAbs) against Akabane virus (AKAV) was developed to detect antibodies to AKAV in cattle sera. The performance of the test using 7 different competitor MAbs was evaluated in sequential serum samples and sera from cattle infected with various bovine arboviruses. The dynamics of the antibody response expressed by percentage of inhibition (PI) in C-ELISA coincided with those of neutralizing antibody titers in sequential serum samples from 2 cattle experimentally infected with AKAV. The value of PI in C-ELISA for convalescent sera from cattle infected with arboviruses correlated with the neutralizing antibody titer to AKAV but was unaffected by the antibodies to other arboviruses. In the validation experiment of C-ELISA using 286 bovine sera previously examined for the AKAV antibody by serum neutralization (SN) test, the relative specificity of C-ELISA was more than 98%, whereas the relative sensitivities of individual MAbs ranged from 49% to 82.2%. Overall agreement between C-ELISA and the SN test varied from 72% to 90% depending on the MAb. These results suggest that the C-ELISA is acceptable as a rapid and specific method for detecting antibodies to AKAV and is a potential alternative to the SN test.     

Malignant pinealoma observed in the deep cerebral parenchyma of a male Wistar rat

This report describes a case of spontaneous malignant pinealoma in a 90-week-old male Wistar rat. The tumor mass occurred in the deep cerebral parenchyma and no intact pineal gland was observed in the area between the posterior-dorsal median line of the cerebrum and the cerebellum. The tumor was characterized by a large nodular proliferation occupying the central area of the brain, extending from the dorsal surface to the base of the brain, corresponding to the thalamus. The tumor cells had round to irregular oblong nuclei approximately 5–17 μm in diameter and showed faintly or moderately eosinophilic cytoplasm and indistinct cell boundaries. Immunohistochemically, the tumor cells were positive for synaptophysin and partially positive for neuron-specific enolase (NSE). The tumor showed malignant features including cellular pleomorphism, high mitotic index, necrotic foci, and invasive and extensive growth and was, therefore, diagnosed as an extremely rare malignant pinealoma in the deep cerebral parenchyma.     

Age estimation of the wild population of Japanese mantis shrimp <Emphasis Type="Italic">Oratosquilla oratoria</Emphasis> (Crustacea: Stomatopoda) in Tokyo Bay,Japan, using lipofuscin as an age marker

ABSTRACT:   In this study, the age composition of the Japanese mantis shrimp, Oratosquilla oratoria , in Tokyo Bay, central Japan, was investigated using lipofuscin, an autofluorescent pigment, as an age marker. Lipofuscin in a histological section of protocerebral bridge cell mass (PBCM) in the brain was identified by confocal microscopy, and its concentration was quantified by image analysis. Modal analysis of the lipofuscin concentration showed four regularly-spaced modes that could each be regarded as a distinct age group. This implied a constant lipofuscin accumulation in PBCM at a 6.5 × 10⁻²% volume fraction per year; it also implied the existence of individuals that are at least 4 years old. The lipofuscin concentration was found to be a more appropriate index than body length for estimating the age of O. oratoria , because the modal analysis on the body–length histogram failed to detect apparent age groups. This was probably a result of the declining growth rate with age and the individual variations in growth through molting leading to considerable overlap in the size between different age groups. The lipofuscin analysis suggested that fast-growing individuals in each cohort are recruited to the fishery, and most individuals attain the exploitable size between 2 and 3 years of age.     

Preferential infection of neuronal and astroglia cells by Akabane virus in primary cultures of fetal bovine brain

Akabane virus is a member of the genus Bunyavirus; it is pathogenic for ruminants and transmitted by arthropod vectors. Infection of adult cattle and sheep causes a transient viremia without obvious clinical signs, while infection of pregnant animals often causes fetal abnormalities including hydranencephaly, poliomyelitis and arthrogryposis. Infectious virus or viral antigens is present in the brain, spinal cord and skeletal muscle of infected fetuses. To understand the interaction between Akabane virus and bovine brain cells, we investigated the viral tropism using primary cultures of fetal bovine brain. The cultured neuronal cells, astroglia cells and microglia cells were distinguished by cell type specific antisera. Akabane virus was found to infect neuronal cells and astroglia cells, which led to degenerative death. No microglia cells were found infected. In some brain cultures, we observed different sensitivities of the cells to two Akabane virus strains: an attenuated strain infected and spread more readily than wild type virus. This difference was not observed in a hamster fibroblast cell line. Both viral and host determinants might be involved in the different susceptibility of brain cells to Akabane virus infection.     

Effect of modified oligopeptides from the beetle Allomyrina dichotoma on Escherichia coli infection in mice

The novel peptides based on a putative active site of defensin, an anti-bacterial peptide from the beetle Allomyrina dichotoma, were synthesized. These synthetic oligopeptides exhibited strong anti-bacterial activity in vitro, even against antibiotic-resistant pathogenic bacteria. Then, anti-bacterial activity of two newly synthesized peptides, RLYLRIGRR-NH(2) (peptide A) and RLRLRIGRR-NH(2) (peptide B) was also examined by macroscopic and histopathologic assessment during the course of infection in mice inoculated with antibiotic-resistant pathogenic Escherichia coli (E. coli) in vivo. Peptide B decreased the mortality of mice inoculated with antibiotic-resistant pathogenic E. coli. The results of macroscopic and histopathologic examinations revealed that peptide B could protect the mice from infection. In contrast, peptide A failed to protect mice from infection with antibiotic-resistant pathogenic E. coli. Also, modified peptides A and B produced no toxicity or side effects in mice. These results suggest that peptide B is useful for developing novel antibiotics against antibiotic-resistant pathogenic bacteria.     

Soybean preference for Bradyrhizobium japonicum for nodulation

For examining the probability of increase in the occupation ratio of inoculated rhizobium in nodules, various Rj-soybean cultivars including the Rj ₂ Rj ₃ Rj ₄-lines of soybean were grown in a field of the Kyushu University Farm. Bradyrhizobium japonicum USDA110 that carries uptake hydrogenase (Hup⁺) was used as an inoculum. The relative efficiency of nitrogen fixation generally increased by the inoculation. However, there were no significant differences in the effects among the genotypes of the host plants. The occupation ratio of serogroup USDA110 in the nodules on the taproot of the inoculated plants was in the range of 77–100%, suggesting that the B. japonicum strain USDA110 infected taproots immediately after inoculation. The occupation ratios in the nodules on the lateral roots were 53–67, 40–86, 63–83, and 62–77% in inoculated plants of the non-Rj-, Rj ₂ Rj ₃-, Rj ₄-, and Rj ₂ Rj ₃ Rj ₄-genotypes, respectively, and they decreased in all the genotypes with the progression of growth. At the time of the first sampling, the occupation ratios on the lateral roots of these Rj ₂ Rj ₃ Rj ₄-genotypes showed values intermediate between those of IAC-2 (Rj ₂ Rj ₃) and Hill (Rj ₄) , which were the parent cultivars of the Rj ₂ Rj ₃ Rj ₄-lines, B340, B349, and C242. The reduction in the occupation ratio of the serogroup USDA110 for about 1 month after the first sampling was the lowest (0.13–0.16) in the Rj ₂ Rj ₃ Rj ₄-genotypes, excluding B349, followed by the non-Rj- and Rj ₂ Rj ₃-genotypes and highest (0.52–0.69) in the Rj ₄-genotypes, excluding Hill. Therefore, it was considered that the population of compatible rhizobia with host soybean plants increased in the rhizosphere with the progression of the development and growth. The results showed that with the expansion of the root area of host plants, the occupation ratio of type A rhizobia including the serogroup USDA110 was high. Therefore, the Rj ₂ Rj ₃ Rj ₄-genotypes were superior to other Rj-genotypes in terms of the inoculation effects of nodulation type A rhizobium, B. japonicum USDA110. However, the preference of the Rj ₂ Rj ₃ Rj ₄-genotype for serogroup USDA110 is not sufficient to rule out the competition with the other serogroups in this study. Therefore, the study should be centered on the isolation of more efficient (Hup⁺) and highly compatible rhizobial strains with the Rj ₂ Rj ₃ Rj ₄- genotypes.     

Effect of various drought stresses and subsequent recovery on proline,total soluble sugar and starch metabolisms in Rice (Oryza sativa L.) varieties

ABSTRACT

Rice (Oryza sativa L.) is one of the most important staple foods in the world, however most improved rice varieties are susceptible to drought stress. A two-year study was conducted to explore the effects of various drought stresses and subsequent recovery on the accumulation and degradation of proline, total soluble sugar and starch in different rice varieties at vegetative stage. The results showed that relative water content in the leaves and sheaths of rice varieties significantly decreased under drought stresses, but not at the same rate. Under control and drought conditions, the water content in sheaths was higher than that in leaves. Interestingly, under severe drought stress in 2015, the leaf water content was higher than the sheath water content. The water distribution between leaves and sheaths might be a response of plants to protect leaf system from devastation by drought. Proline was highly accumulated under drought stress but rapidly decreased after re-watering. The drought tolerant variety DA8 expressed higher ability in accumulation of proline than susceptible varieties. In general, total soluble sugar and starch contents in leaves and sheaths of varieties decreased under drought stress conditions. Total soluble sugar and starch content of DA8 were less affected than other varieties under drought conditions. Our study indicated that metabolisms of total soluble sugar and starch in rice were affected by both environmental conditions and characteristics of varieties. Proline accumulation ability of varieties can be used as a useful indicator for drought tolerant potential in rice breeding for water-limited environments.     

Identification and characterization of foliar polyphenolic composition in sweetpotato (Ipomoea batatas L.) genotypes

Trials over two years were conducted using 1389 sweetpotato (Ipomoea batatas L.) genotypes collected from all over the world to characterize the polyphenolic composition in sweetpotato leaves. Wide variation was observed in relation to their total and individual leaf polyphenolic constituents. In all genotypes studied, the total polyphenol contents of sweetpotato leaf ranged from 1.42 to 17.1 g/100 g dry weight. The six different polyphenolic compounds were identified and quantified by NMR, FABMS, and RPHPLC analysis procedures. This is the first report of polyphenolic compositions in sweetpotato leaves. The relative levels of polyphenolic acids in sweetpotato leaves were as follows: 3,5-di-O-caffeoylquinic acid > 4,5-di-O-caffeoylquinic acid > chlorogenic acid (3-O-caffeoylquinic acid) > 3,4-di-O-caffeoylquinic acid > 3,4,5-tri-O-caffeoylquinic acid > caffeic acid. The highest 3,4,5-tri-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid occurred at 221 and 1183.30 mg/100 g dry weight, respectively.     

Effects of salts and moisture content on N2O emission and nitrogen dynamics in Yellow soil and Andosol in model experiments

 The effects of salt type and its concentration on nitrification, N mineralization and N₂O emission were examined under two levels of moisture content in Yellow soil and Andosol samples as simulated to agriculture under arid/semi-arid conditions and under heavy application of fertilizer in a glass-house, respectively. The salt mixtures were composed of chlorides (NaCl and NH₄Cl) or sulphates [Na₂SO₄ and (NH₄)₂SO₄] and were added at various concentrations (0, 0.1, 0.2, 0.4 and 0.6 M as in the soil solution). These salts were added to non-saline Yellow soil at different moisture contents (45 or 40 and 65% of maximum water-holding capacity; WHC) and their effects on the changes in mineral N (NH₄ ⁺-N and NO₃ ^–-N) concentration as well as N₂O emission were examined periodically during laboratory incubation. We also measured urease activities to know the effect of salts on N mineralization. Furthermore, Ca(NO₃)₂ solution was added at various concentrations (0, 0.1, 0.3, 0.5 and 0.8 M as in the soil solution) to a non-saline Andosol taken from the subsurface layer in a glass-house and incubated at different moisture contents (50% and 70% of WHC) to examine their effects on changes in mineral N. Nitrification was inhibited by high, but remained unaffected by low, salt concentrations. These phenomena were shown in both the model experiments. It was considered that the salinity level for inhibition of nitrification was an electric conductivity (1 : 5) of 1 dS m^–1. This level was independent of the type of salts or soil, and was not affected by soil moisture content. The critical level of salts for urease activities was about 2 dS m^–1. The emission rate of N₂O was maximum at the beginning of the incubation period and stabilized at a low level after an initial peak. There was no significant difference in N₂O emission among the treatments at different salt concentrations, while higher moisture level enhanced N₂O emission remarkably. Received: 29 July 1998