Intra-strain biological and epidemiological characterization of plum pox virus

Plum pox virus (PPV) is one of the most important plant viruses causing serious economic losses. Thus far, strain typing based on the definition of 10 monophyletic strains with partially differentiable biological properties has been the sole approach used for epidemiological characterization of PPV. However, elucidating the genetic determinants underlying intra-strain biological variation among populations or isolates remains a relevant but unexamined aspect of the epidemiology of the virus. In this study, based on complete nucleotide sequence information of 210 Japanese and 47 non-Japanese isolates of the PPV-Dideron (D) strain, we identified five positively selected sites in the PPV-D genome. Among them, molecular studies showed that amino acid substitutions at position 2,635 in viral replicase correlate with viral titre and competitiveness at the systemic level, suggesting that amino acid position 2,635 is involved in aphid transmission efficiency and symptom severity. Estimation of ancestral genome sequences indicated that substitutions at amino acid position 2,635 were reversible and peculiar to one of two genetically distinct PPV-D populations in Japan. The reversible amino acid evolution probably contributes to the dissemination of the virus population. This study provides the first genomic insight into the evolutionary epidemiology of PPV based on intra-strain biological variation ascribed to positive selection.     

IL1RAPL1 Associated with Mental Retardation and Autism Regulates the Formation and Stabilization of Glutamatergic Synapses of Cortical Neurons through RhoA Signaling Pathway

Interleukin-1 receptor accessory protein-like 1 (IL1RAPL1) is associated with X-linked mental retardation and autism spectrum disorder. We found that IL1RAPL1 regulates synapse formation of cortical neurons. To investigate how IL1RAPL1 controls synapse formation, we here screened IL1RAPL1-interacting proteins by affinity chromatography and mass spectroscopy. IL1RAPL1 interacted with Mcf2-like (Mcf2l), a Rho guanine nucleotide exchange factor, through the cytoplasmic Toll/IL-1 receptor domain. Knockdown of endogenous Mcf2l and treatment with an inhibitor of Rho-associated protein kinase (ROCK), the downstream kinase of RhoA, suppressed IL1RAPL1-induced excitatory synapse formation of cortical neurons. Furthermore, we found that the expression of IL1RAPL1 affected the turnover of AMPA receptor subunits. Insertion of GluA1-containing AMPA receptors to the cell surface was decreased, whereas that of AMPA receptors composed of GluA2/3 was enhanced. Mcf2l knockdown and ROCK inhibitor treatment diminished the IL1RAPL1-induced changes of AMPA receptor subunit insertions. Our results suggest that Mcf2l-RhoA-ROCK signaling pathway mediates IL1RAPL1-dependent formation and stabilization of glutamatergic synapses of cortical neurons.     

Induction of localized auxin response during spontaneous nodule development in Lotus japonicus

In leguminous plants, rhizobial infection of the epidermis triggers proliferation of cortical cells to form a nodule primordium. Recent studies have demonstrated that two classic phytohormones, cytokinin and auxin, have important functions in nodulation. The identification of these functions in Lotus japonicus was facilitated by use of the spontaneous nodule formation 2 (snf2) mutation of the putative cytokinin receptor LOTUS HISTIDINE KINASE 1 (LHK1). Analyses using snf2 demonstrated that constitutive activation of cytokinin signaling causes formation of spontaneous nodule-like structures in the absence of rhizobia and that auxin responses are induced in proliferating cortical cells during such spontaneous nodule development. Thus, cytokinin signaling positively regulates the auxin response. In the present study, we further investigated the induction of the auxin response using a gain-of-function mutation of Ca²⁺/calmodulin-dependent protein kinase (CCaMK) that causes spontaneous nodule formation. We demonstrate that CCaMK^T265D-mediated spontaneous nodule development is accompanied by a localized auxin response. Thus, a localized auxin response at the site of an incipient nodule primordium is essential for nodule organogenesis.     

Flavonoids isolated from the leaves of Melicope triphylla and their extracellular-superoxide dismutase-inducing activity

Two novel flavonoids, named meliflavones A (1) and B (2), were isolated from the leaves of Melicope triphylla (Lam.) Merr., along with thirteen known compounds (3–15). Four of the polymethoxyflavonoids bearing a prenyloxy (3-methylbut-2-enyloxy) function (1, 3–5) induced the expression of extracellular-superoxide dismutase (EC-SOD) in a human leukemic U937 cell-based assay.     

Novel isolation of resveratrol dimer O-glucosides with enantiomeric aglycones from the leaves of Shorea cordifolia

Two O-glucosides of resveratrol dimers, ampelopsin F-11b-O-β-glucopyranosides with enantiomeric aglycones [cordifoloside A (1) and cordifoloside B (2)] and an enantiomer of the aglycone [(?)-ampelopsin F] were isolated from the leaves of Shorea cordifolia (Dipterocarpaceae). These structures were identified on the basis of spectroscopic evidence and their absolute configurations were elucidated using circular dichroism data. This is the first report on oligostilbenoids that demonstrates the co-occurrence of diastereomeric O-glucosides with enantiomeric aglycones in this family.     

Detection of Spiroplasma from the mite Macrocheles sp. (Acari; Macrochelidae) ectoparasitic to the fly Drosophila hydei (Diptera; Drosophilidae): a possible route of horizontal transmission?

Some members of the genus Spiroplasma are vertically transmitted endosymbionts of insects. Among them, Spiroplasma sp. Dhd, a member of the Spiroplasma poulsonii clade, is highly prevalent among worldwide populations of Drosophila hydei. Here we found that 53 out of 3,763 wild-caught D. hydei (1.4 %) were ectoparasitized by the mite that belong to the genus Macrocheles. Many of the ectoparasitized flies (79 %) had a single mite, but some flies had up to five mites. Among 59 mites subjected to Spiroplasma-specific PCR, 15 individuals were found to be positive. Infection status of Spiroplasma in flies and the associated mites were incongruent. Partial nucleotide sequences of the Spiroplasma P58 gene suggest that some of the mites are infected with a Spiroplasma, which is identical or closely related to Spiroplasma sp. Dhd. This finding provides a potential route of horizontal Spiroplasma transmission between D. hydei individuals in natural populations. In addition, a Spiroplasma strain that does not form a monophyletic group with S. poulsonii was also found from a mite individual.     

Lead optimization of 5-amino-6-(2,2-dimethyl-5-oxo-4-phenylpiperazin-1-yl)-4-hydroxyhexanamides to reduce a cardiac safety issue: Discovery of DS-8108b,an orally active renin inhibitor

With the aim to address an undesired cardiac issue observed with our related compound in the recently disclosed novel series of renin inhibitors, further chemical modifications of this series were performed. Extensive structure–activity relationships studies as well as in vivo cardiac studies using the electrophysiology rat model led to the discovery of clinical candidate trans-adamantan-1-ol analogue 56 (DS-8108b) as a potent renin inhibitor with reduced potential cardiac risk. Oral administration of single doses of 3 and 10 mg/kg of 56 in cynomolgus monkeys pre-treated with furosemide led to significant reduction of mean arterial blood pressure for more than 12 h.     

Studies on Nicotinoids1) as an Insecticide

Toxicities of some nicotinoids as an insecticide were determined. 5′-methylnornicotine, a new synthetic isomer of nicotine, shows similar toxicity to nicotine. The essential moiety in nicotinoids molecule responsible for high toxicity may be 3-pyridylmethylamine group, the amino nitrogen of which must have high basicity (p^K_a′: 7.4~9.0). All nicotinoids of high toxicity are estimated to be largely as monocation at physiological pH of 7.     

Demethylthiolating Agents for Ribonucleoside 5′-S-Methyl Phosphorothiolates

Several oxidizing agents were examined for their ability to demethylthiolate adenosine- and cytidine 5′-S-methyl phosphorothiolates.

Iodine dissolved in an aqueous potassium iodide solution or in dimethyl sulfoxide (DMSO) was the most effective demethylthiolating agent of those tested in the present study, rapidly giving the demethylthiolated products in quantitative yields. The iodine-DMSO solution demethyl-thiolated the ribonucleoside 5′-S-methyl phosphorothiolates to give ribonucleoside 5′-monophosphates even under anhydrous conditions, DMSO acting as an oxygen donor in this reaction.

Hydrogen peroxide has high demethylthiolating ability in spite of its low reaction rate. Isoamyl nitrite, an effective demethylthiolating agent for O-alkyl S-methyl phosphorothiolates, was not effective for the demethylthiolation of ribonucleoside 5′-S-methyl phosphorothiolates, because the unprotected amino groups of the S-methyl nucleotides were attacked by the reagent to give deaminated products. N-Chlorosuccinimide had no effect on the demethylthiolation of S-methyl phosphorothiolates.