A latex agglutination test for the detection of Echinococcus multilocularis coproantigen in the definitive hosts

A latex agglutination test for detecting Echinococcus multilocularis coproantigen in definitive hosts was developed using latex beads sensitized with EmA9 monoclonal antibody raised against somatic antigens of adult E. multilocularis. A primary test (LA 1) was performed on 82 fecal samples of necropsied foxes, of which 46 were infected, and resulted in 61% sensitivity and 86% specificity. To increase the sensitivity, 4 ng/mL of excretory/secretory antigens of adult worms was added to the samples in a secondary test (LA 2), resulting in 91% sensitivity and 61% specificity. The positive predictive value of the LA 1 test and the negative predictive value of the LA 2 test were both 85%. The combination of the LA 1 and LA 2 tests is applicable and practical for use in situations that require quick diagnosis or screening based on the following interpretation: the samples that are positive in the LA 1 test are positive; the samples that are negative in the LA 2 test are negative; and the samples that are negative in the LA 1 test and positive in the LA 2 test are classified as suspicious.     

Comparative hepatotoxicity of a herbicide,epyrifenacil, in humans and rodents by comparing the dynamics and kinetics of its causal metabolite

A new herbicide, epyrifenacil (S-3100), inhibits protoporphyrinogen oxidase (PPO) in plants. Repeated administration of epyrifenacil in laboratory animals led to some toxicological changes related to PPO inhibition, e.g., hepatotoxicity caused by porphyrin accumulation and anemia caused by the inhibition of heme biosynthesis. In vitro studies revealed that an ester-cleaved metabolite, S-3100-CA, is predominant in mammals, exhibits PPO-inhibitory activity, and thus is the cause of epyrifenacil-induced toxicity. To assess the human risk, the effects of species differences on the dynamics (PPO inhibition) and kinetics (liver uptake) of epyrifenacil were evaluated separately. The results of in vitro assays revealed an approximately tenfold weaker inhibition of PPO by S-3100-CA in humans than in rodents and six- to thirteen-fold less hepatic uptake of S-3100-CA in humans than in mice. Finally, it was suggested that humans are less sensitive to the toxicity of epyrifenacil than are rodents, although further mechanistic research is highly anticipated.     

Comparative observations on the growth changes of the histochemical property and collagen architecture of the Musculus pectoralis from Silky, layer-type and meat-type cockerels

Growth‐related changes in the histochemical properties and collagen architecture of the Musculus pectoralis were compared among Silky, layer‐type and meat‐type cockerels. Histochemical and immunohistochemical methods were used and collagen architecture was studied using scanning electron microscopy. The total amount of collagen present was also measured. The diameter of type IIB myofibers was similar or rather larger in the layer‐type birds compared with the meat‐type. The collagen content was generally low for 5–10 weeks across the breeds and then increased in the other breeds except for Silky. In the perimysium, the collagen bundles gradually increased in size and the density of the fibrils also increased during growth. At 30 weeks of age, the layer‐type birds showed compact collagen bundles while the meat‐type had loose bundles. The endomysial collagen network appeared relatively denser in the meat‐type chicks compared to the others at week 1. At 30 weeks of age, compact and felt‐like structure of endomysium was shown by Silky and layer‐type chickens, while the meat‐type showed a relatively loose arrangement of tissue in the endomysial collagen. From these results, it appears that the meat‐type chicken can produce a large M. pectoralis with many, relatively thinner myofibers and a relatively undeveloped form of intramuscular collagen structure.     

Activation of GABA(A) receptors in the accessory olfactory bulb does not prevent the formation of an olfactory memory in mice

When female mice are mated, they form a memory to the pheromonal signal of their male partner. The neural mechanisms underlying this memory involve changes at the reciprocal dendrodendritic synapses between glutamatergic mitral cells and gamma-aminobutyric acid (GABA)-ergic granule cells in the accessory olfactory bulb (AOB). Blockade of GABA(A) receptors in the AOB leads to the formation of an olfactory memory. In an attempt to disrupt memory formation at mating, we used local infusions of the GABA(A) receptor agonist muscimol into the AOB during the critical period for memory formation. Muscimol across a wide range of doses (1-1000 pmol) did not prevent memory formation. The resistance of this memory to GABA(A) receptor activation may reflect the complexity of synaptic microcircuits in the AOB.     

Vibrational properties of heat-treated green wood

To investigate the influence of water on heat treatment, green wood was heat-treated. Sitka spruce (Picea sitchensis Carr.) with about 60% moisture content (MC) was used. Young's modulus and loss tangent were measured by the free-free flexural vibration test. The specimens were heated in nitrogen at 160°C for 0.5h. The results were as follows. (1) Recognizing that the effects of heat treatment are mild and that the same specimens cannot be used for both heat treatment and as controls, it was necessary to investigate the effects of the heat treatment based on the variations of properties in the whole of the test lumber. (2) Young's modulus increased and the loss tangent decreased due to heat treatment. When the vibrational properties were measured at various MCs, the MCs at the maximum value of Young's modulus and the minimum value of the loss tangent were lower in heat-treated specimens than in controls. The effects of heat treatment in green wood were similar to those in air-dried wood. (3) The loss tangents of heat-treated specimens were smaller than those of controls at about 0% MC but were larger than those of controls at about 10% MC. We thought that this resulted from the decreased MC at the minimum loss tangent after the heat treatment mentioned above. (4) The properties measured at several MCs were more useful than those at only one moisture content for investigating the effects of heat treatment.This study was presented in part at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 3–5, 1996; and at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 3–5, 1997     

Photosynthetic capacity and nitrogen partitioning in foliage of the evergreen shrub Daphniphyllum humile along a natural light gradient

We examined the effects of leaf age and mutual shading on the morphology, photosynthetic properties and nitrogen (N) allocation of foliage of an evergreen understory shrub, Daphniphyllum humile Maxim, growing along a natural light gradient in a deciduous Fagus crenata-dominated forest in Japan. Seedlings in high-light environments were subject to greater mutual shading and 1-year-old foliage survival was lower than in seedlings in low-light environments, indicating that the survival rates of foliage were related to the degree of mutual shading. Although specific leaf area (SLA) in current- and 1-year-old foliage was curvilinearly related to daily photosynthetic photon flux (PPF), SLA was unaffected by leaf age, indicating that foliage in D. humile may not acclimate morphologically to annual changes in light caused by mutual shading. Light-saturated net photosynthetic rates (Pmax) were correlated with daily PPF in current-year foliage. In addition, a strong, positive relationship was found between nitrogen concentration per unit leaf area and Pmax. In contrast, the relationship among PPF, N and photosynthetic parameters in 1-year old foliage was weak because of the strong remobilization of N from older leaves to current-year foliage in plants growing in high light. However, the relationship between daily PPF and both photosynthetic N-use efficiency and the ratio of maximum electron transport rate to maximum carboxylation rate did not differ between current-year and 1-year-old foliage, suggesting that these responses help maintain a high photosynthetic efficiency even in older foliage. We conclude that D. humile maximizes whole-plant carbon gain by maintaining a balance among photosynthetic functions across wide ranges of leaf ages and light environments.     

Mechanisms of nematode suppression by organic soil amendments—A review

Application of organic soil amendments is a traditional control method for plant–parasitic nematodes and it is considered a part of nematode-management programs. A variety of organic amendments, such as animal and green manures, compost, nematicidal plants and proteinous wastes, are used for this purpose, but nematode control efficacy is not always satisfactory. Elucidation of nematode-control mechanisms in amended soil may lead to improved efficacy or the development of more effective control techniques, although the effects of organic amendments on nematodes, microbial communities, plants and soil environments are very complex. Possible mechanisms involved in nematode suppression are: (1) release of pre-existing nematicidal compounds in soil amendments, (2) generation of nematicidal compounds, such as ammonia and fatty acids, during degradation, (3) enhancement and/or introduction of antagonistic microorganisms, (4) increase in plant tolerance and resistance, and (5) changes in soil physiology that are unsuitable for nematode behavior. Combinations of these mechanisms, rather than a single one, appear to produce nematode suppression in amended soils.