Two allelopathic substances from Paspalum commersonii Lam.

Paspalum commersonii (Poaceae) is a herbaceous perennial weed distributed in the tropics and subtropics regions and grows mainly in the moist, or even flooded soil. It often appears in the rice field as a competitive weed and difficult to manage. Its strong competitive nature indicates possible allelopathic potential of P. commersonii. However, no studies have been found yet on the allelopathic activity of P. commersonii. Thus, we investigated the allelopathic potential of this weed and determined its allelopathic substances. Aqueous methanol extracts of P. commersonii showed concentration-dependent inhibitory activity on the seedling growth of cress, alfalfa, rapeseed, lettuce, barnyard grass, foxtail fescue, Italian ryegrass, and timothy. Two substances were isolated through bioassay-guided fractionation and their structures were determined through spectral data as dehydrovomifoliol and loliolide. Dehydrovomifoliol and loliolide started inhibiting the shoot and root growth of cress at concentrations greater than 3 and 0.03?mM, respectively. The concentrations required for 50% inhibition (I₅₀) of cress shoot and root growth were 3.34 and >3.50?mM for dehydrovomifoliol and 0.04 and 0.05?mM for loliolide, respectively. These results indicate that both substances may affect the inhibitory activity of P. commersonii.     

Plant growth and nutrition in pine (Pinus thunbergii) seedlings and dehydrogenase and phosphatase activity of ectomycorrhizal root tips inoculated with seven individual ectomycorrhizal fungal species at high and low nitrogen conditions

We investigated the functions and ecological traits of seven individual ectomycorrhizal (ECM) fungal species derived from a Pinus thunbergii-dominated (nitrogen-poor) and a Robinia pseudoacacia-dominated (nitrogen-rich) area. P. thunbergii seedlings were inoculated with seven individual ECM fungal species and cultured under high nitrogen (nitrogen group) and low nitrogen (control group) conditions. Control seedlings were not inoculated with any ECM fungus. Seedlings harvested were examined for the numbers of non-mycorrhizal and ECM root tips, growth, nutrient status (nitrogen, phosphorus and carbon) and the activity of dehydrogenase and phosphomonoesterase in the root tips. The relationships among the growth, nutrient status and the enzymatic activity in the seedlings inoculated with each ECM fungal species were also analyzed by canonical discriminants. As the results, inoculation of ECM fungi made the plant growth significantly higher than those of non-inoculated seedlings. Plant growth significantly correlated with the phosphorus content, N:P ratio and phosphomonoesterase activity, especially in the nitrogen group. Dehydrogenase and phosphomonoesterase activities in the seedlings were higher when the ECM fungi from a nitrogen-rich area were inoculated than when those from a nitrogen-poor area were inoculated. The canonical discriminant analyses separated seedlings by inocula: no fungus, ECM fungi from a nitrogen-poor area, and those from a nitrogen-rich area. These results suggested the possibility that nitrogen deposition caused P shortage and the P absorbing ability was higher in the ECM fungi in nitrogen-rich forests than those in nitrogen-poor forests.     

Evaluation of phytotoxic potential and identification of phytotoxic substances in Cassia alata Linn. leaves

Cassia alata (Caesalpiniaceae) is a large perennial shrub native to tropical America. It is an important medicinal and ornamental plant and has been reported to possess several pharmacological properties. However, phytotoxic substances from C. alata have not yet been documented in the literature. Therefore, this study seeks to evaluate the phytotoxic potential of C. alata leaves and to identify inhibitory substances for the purpose of eco-friendly weed management. The effect of aqueous methanol extracts of C. alata on the seedling growth of alfalfa, cress, lettuce, rapeseed, barnyard grass, foxtail fescue, Italian ryegrass, and timothy was examined. The level of inhibition of the extracts corresponded to concentration. Several chromatographic steps were performed to separate the extracts, and through spectroscopic analysis, two active substances were isolated and characterised as rutin and syringone. These two active substances significantly inhibited the seedling growth of cress and foxtail fescue. The range of I₅₀ values (required concentration for 50% growth inhibition) of rutin and syringone for the seedling growth of cress and foxtail fescue were 129.5–417.8 and 160.1–466.5?µM, respectively. These results indicate that the two identified active phytotoxic substances from C. alata may be responsible for its growth inhibitory properties.     

Production of recombinant extracellular domains of canine desmoglein 1 (Dsg1) by baculovirus expression

The aim of this study was to generate a recombinant protein to represent the entire extracellular domain of canine desmoglein 1 (Dsg1), a desmosomal cell-cell adhesion molecule, by the baculovirus expression system. Cotransfection of a baculovirus transfer vector containing the cDNA for the entire extracellular domain of canine Dsg1 with baculovirus DNA into insect cells resulted in the secretion of soluble canine Dsg1 into insect culture supernatants. Immunoreactivity of 11 human pemphigus foliaceus (PF) sera against the cell surface of canine keratinocytes was completely removed when the sera were preincubated with the canine Dsg1 baculoprotein. This recombinant canine Dsg1 produced by baculovirus shares the major epitopes of the authentic canine Dsg1 recognized by human PF sera, and will be useful in studying the molecular pathophysiological mechanisms in PF and impetigo in canine patients.     

Atopic NC/Nga mice as a model for allergic asthma: severe allergic responses by single intranasal challenge with protein antigen

Since certain characters of allergic asthma are common with other allergic disorders like atopic dermatitis, the possible relationship in etiology is expected. Herein, we investigated whether NC/Nga mice, an inherent animal model for human atopic dermatitis, are inclined to allergic asthma. A single intranasal challenge of NC/Nga mice immunized with ovalbumin (OVA) resulted in an increase in plasma levels of OVA-specific IgE, and typical pathological aspects of allergic asthma characterized by infiltration of numerous eosinophils, mucus hyper production of bronchial epithelial cells. Moreover, airway hyperresponsiveness to inhaled acetylcholine and marked enhancement of airway resistance after the challenge were observed as compared to control BALB/c mice. Delayed expression of mRNA of eosinophil active chemokines, interleukin-5, eotaxin, macrophage inflammatory protein-1alpha in concert with eosinophilia was determined in the lung of NC/Nga mice. These results suggest that asthmatic responses developed in NC/Nga mice challenged with OVA are very similar to human allergic asthma, and that NC/Nga mice are a useful model to elucidate various aspects of allergic asthma.     

Atopic NC/Nga mice as a model for allergic asthma: cytokine profiles and eosinophil productivity of bone marrow

In previous study, NC/Nga mice with experimentally induced asthma showed severe eosinophilia. To explore the mechanism, profiles of representative cytokines interleukin (IL)-4, IL-5, and interferon (IFN)-gamma were examined in bronchoalveolar lavage fluid. The level of only IFN-gamma was lower in NC/Nga mice than control BALB/c mice. Furthermore, bone marrow cell culture system under the presence of eosinopoietic cytokines, which induce the differentiation of progenitor cells into mature eosinophils, showed that a larger number of eosinophils differentiated from NC/Nga mice derived bone marrow cells than from control BALB/c mice. These results may imply the possibility that severe eosinophilia in the NC/Nga mice are attributable to lower production of IFN-gamma and higher eosinophil productivity of bone marrow cells.     

Allelic variation of the D4 dopamine receptor polymorphic region in two dog breeds, Golden retriever and Shiba

The D4 dopamine receptor (D4DR) polymorphic region, which is possibly related to the personality trait known as novelty seeking in humans, was examined in 34 dogs from two breeds (Golden retriever and the Japanese indigenous breed, Shiba) by the polymerase chain reaction (PCR), and the DNA sequences of each allele were determined. The polymorphic region of the dog D4DR gene was composed of 39- and 12- base pair (bp) units, and four alleles (A-D) were identified based on the number and/or order of these units. Intra- and inter-breed allele variations were observed. The frequency of the short A allele was dominant (78.9%) in the Golden retriever, while the long D allele was most common (46.7%) in the Shiba. These findings suggested that the allele frequency varied significantly between different breeds, and that analysis of the polymorphism in D4DR might be of use for understanding the behavioral traits of dogs.