Resistance to pathogens in terpene down-regulated orange fruits inversely correlates with the accumulation of D-limonene in peel oil glands

Volatile organic compounds (VOCs) are secondary metabolites acting as a language for the communication of plants with the environment. In orange fruits, the monoterpene D-limonene accumulates at very high levels in oil glands from the peel. Drastic down-regulation of D-limonene synthase gene expression in the peel of transgenic oranges harboring a D-limonene synthase transgene in antisense (AS) configuration altered the monoterpene profile in oil glands, mainly resulting in reduced accumulation of D-limonene. This led to fruit resistance against Penicillium digitatum (Pd), Xanthomonas citri subsp. citri (Xcc) and other specialized pathogens. Here, we analyze resistance to pathogens in independent AS and empty vector (EV) lines, which have low, medium or high D-limonene concentrations and show that the level of resistance is inversely related to the accumulation of D-limonene in orange peels, thus explaining the need of high D-limonene accumulation in mature oranges in nature for the efficient attraction of specialized microorganism frugivores.     

Spin Trapping Isotopically-Labelled Nitric Oxide Produced from [15n]L-Arginine and [17ojdioxygen by Activated Macrophages Using a Water Soluble Fe++-Dithiocarbamate Spin Trap

The unique capabilities of EPR spin trapping of nitric oxide based on a ferrous-dithiocarbamate spin trap have been demonstrated in a study verifying the source of the nitrogen and oxygen atoms in nitric oxide produced from activated macrophages. Spin trapping experiments were performed during nitric oxide generation from activated mouse peritoneal macrophages using the ferrous complex of N-methyl D-glucam-ine dithiocarbamate as a spin trap. When ¹⁵N-substituted arginine was given to the activated macrophages in the presence of the spin trap, a characteristic EPR spectrum of the nitric oxide spin adduct was obtained, which indicates the presence of the ^l5N atom in the nitric oxide molecule. The hyperfine splitting (hfs) constant of the ^l5N nucleus was 17.6 gauss. When ^l7O-containing dioxygen (55%) was supplied to the medium, an EPR spectrum consistent with the “O-substituted nitric oxide spin adduct was observed in the composite spectrum. The hfs of “O was estimated to be 2.5 gauss. The ^l4NO spin adduct observed after prolonged incubation in the medium which contains [^l5N]L-arginine as the only extracellular source of arginine demonstrates that arginine is recycled through its metabolite in activated macrophages.     

Mutations of the CD40 ligand gene in 13 Japanese patients with X-linked hyper-IgM syndrome

X-linked hyper-IgM syndrome (XHIM) is a rare primary immunodeficiency caused by a defective CD40 ligand. We identified mutations of the CD40 ligand gene in 13 unrelated Japanese XHIM patients. Of the four patients with missense mutations, one had a mutation within the transmembrane domain, and the three others had mutations affecting the TNF homology region of the extracellular domain. Two of the missense mutations resulted in the substitution of amino acids that are highly conserved in TNF family proteins. Three patients had nonsense mutations, all of which resulted in the truncation of the TNF homology domain of the CD40 ligand. Three patients had genomic DNA deletions of 2, 3 or 4 nucleotides, respectively. All of the deletions were flanked by direct repeat sequences, suggesting that these deletions were caused by slipped mispairing. Three patients had mutations within introns resulting in altered splicing, and multiple splicing products were found in one patient. Thus, each of the 13 Japanese patients had different mutations, 9 of them being novel mutations. These results indicate that mutations in XHIM are highly heterogeneous, although codon 140 seems to be a hot spot of the CD40 ligand gene since two additional point mutations were located at Trp 140, bringing the total numbers of mutations affecting codon 140 to six. In one XHIM family with a missense mutation, prenatal diagnosis was performed by single-strand conformation polymorphism analysis of genomic DNA of a male fetus. Received: 20 August 1996     

Cyclical mechanical stretch enhances degranulation and IL‐4 secretion in RBL‐2H3 mast cells

Mast cells are widely distributed in the body and affect their surrounding environment through degranulation and secretion of cytokines. Conversely, mast cells are influenced by environmental stimuli such as cyclical mechanical stretch (CMS), such as that induced by heartbeat and respiration. Peripherally distributed mast cells are surrounded by extracellular matrix, where they bind IgE on their surface by expressing the high‐affinity Fc receptor for IgE (FcεRI), and they release mediators after cross‐linking of surface‐bound IgE by allergen. To analyse how CMS affects mast cell responses, we examined the effect of applying CMS on the behaviour of IgE‐bound mast cells (RBL‐2H3 cell line) adhering to fibronectin as a substitute for extracellular matrix. We found that CMS enhanced FcεRI‐mediated secretion in the presence of antigen (2,4‐dinitrophenol–bovine serum albumin). CMS increased expression of IL‐4 mRNA and secretion of IL‐4 protein. Western blot analysis showed that CMS changes the signal transduction in mitogen‐activated protein kinases and AKT, which in turn alters the regulation of IL‐4 and increases the secretion of IL‐4. These results suggest that CMS modulates the effect of mast cells on inflammation and resultant tissue remodelling. Understanding how CMS affects mast cell responses is crucial for developing therapies to treat mast cell‐related diseases. Copyright © 2013 John Wiley & Sons, Ltd.     

Phylogenetic position of Rickettsia tsutsugamushi and the relationship among its antigenic variants by analyses of 16S rRNA gene sequences

Abstract The 16S rRNA gene sequences of Rickettsia tsutsugamushi and Rickettsia sibirica were determined by PCR and DNA sequencing. Phylogenetic analysis revealed that R. sibirica is positioned in a cluster of the genus Rickettsia with a similarity value of 98.1–99.6%, whereas R. tsutsugamushi is located apart from the cluster with a similarity value of 90.2–90.6%. This evidence suggests that R. tsutsugamushi should be excluded taxonomically from the genus Rickettsia . The phylogenetic classification of six antigenic variants in R. tsutsugamushi moderately reflected their antigenic relationship known in closely and distantly related strains.     

Agricultural Activities of a Meadow Eliminated Plant Litter from the Periphery of a Farmland in Inner Mongolia,China

The purpose of our investigation was to clarify the effects of agriculture on the process of loss of litter at the periphery of a farmland. This study revealed the generation process of an ecologically unusual phenomenon that is observed around cropland in semi-arid regions. We hypothesized that the vegetation around a farmland cannot supply plant litter to the ground surface because the ecological structure has been changed by agricultural activities. The study was conducted at Xilingol steppe, Xilingol League, Inner Mongolia Autonomous Region, China. Four study lines were established from the edge of an arable field to the surrounding meadow and parallel to the wind direction during the strong wind season. Key measurement for each line was set at the border between the farmland and steppe. Four study sites were set at intervals along each line. Plant litter, soil particle size distribution, plant species composition, plant volume, and species diversity were investigated. Despite using the same mowing method at the meadows of all study sites, the litter at the only periphery of the farmland completely disappeared. Soil particle size distribution in steppe, which was adjacent to the farmland, was similar to that of the farmland. Plant community structure at the periphery of the farmland was different from that of the far side from the farmland. This implies that soil scattered from the farmland affected the species composition of the steppe. Consequently, the change in plant community structure induced litter loss because of mowing. We concluded that plant litter was lost near the farmland because of the combined effects of farming and mowing. The results support our hypothesis that the vegetation around a farmland cannot supply plant litter because the ecological structure has been changed by agricultural activities.     

Capability of intensity discrimination in multiple receptor model of insect taste

A simple model in which one CNS taste neuron integrates inputsfrom multiple peripheral receptors is introduced in order toinvestigate the mechanism of acute intensity taste discriminationin flies. Information theory is applied to evaluate the acuteability of discrimination provided by the model. The presentanalysis is carried out under two statistical conditions concerningthe uncertainty of receptor response. Based on experimentaldata obtained by Smith et al. (1983), we estimate the mutualinformation entropy of the model. The numerical results obtainedhere indicate that the uncertainty observed in a single receptorresponse is dramatically reduced by the central integration.Furthermore, each of the eleven stimulus intensity levels experimentallyapplied by Smith et al., can be discriminated completely byintegrating the responses of the realistic number of receptors(33–212). Such a great improvement of the differentialsensitivity in the model resolves the discrepancy between thelow differential sensitivity of single sugar receptors (Smithet al., 1983) and the high sensitivity obtained in the feedingbehavior (Dethier and Rhoades, 1954; Dethier and Bowdan, 1984)of the blowfly.