Analysis of internal transcribed spacer (ITS) region of Phytophthora tropicalis causing quick wilt disease of black pepper in Vietnam

Phytophthora quick wilt is a devastating disease of black peppers in Vietnam. The internal transcribed spacer (ITS) region of the ribosomal DNA of four Phytophthora samples isolated from the diseased vines in Daknong province of the central highland part of Vietnam was Polymerase chain reaction-amplified, cloned, sequenced and characterised. Database search have showed that they are most closely related to an isolate of Phytophthora tropicalis from Taiwan. Sequence comparisons and phylogenetic analyses based on the ITS region of the four Vietnamese and other GenBank isolates of P. tropicalis and a closely related species, P. capsici, provide strong evidences that the Vietnamese isolates are all different isolates of P. tropicalis.     

Two new 11-noriridoids from the aerial parts of Morinda umbellata

This work was done as a part of our ongoing projects to catalog the chemical constituents and biological activities of the Morinda species growing in Vietnam. Phytochemical investigations of the methanol extract of Morinda umbellata aerial parts resulted in the isolation of two new 11-noriridoids, umbellatolides A (1) and B (2). Their structures were elucidated by NMR (¹H NMR, ¹³C NMR, HSQC, HMBC, ¹H–¹H COSY, and NOESY) and FTICRMS data. This is the first report of 11-noriridoids from M. umbellata. The cytotoxic activity and protective effect on oxidative stress injury stimulated by H₂O₂ in murine hepatocyte of 1 and 2 were also evaluated.     

Antioxidant activity of a new C-glycosylflavone from the leaves of Ficus microcarpa

By bioactive-guided fractionation of methanol extract of the Ficus microcarpa leaves, one new C-glucosylflavone, ficuflavoside (1), one new megastigmane glycoside, ficumegasoside (8), and twelve known compounds including flavonoids (2-6), phenylpropanoids (7), megastigmanes (9-11) and sterol derivatives (12-14) were isolated. Their chemical structures were elucidated by mass, 1D, and 2D NMR spectroscopies. The antioxidant activities of these compounds were measured using the oxygen radical absorbance capacity methods. Compounds 1-6 exhibited potent antioxidant activities of 6.6-9.5 μM Trolox equivalents at the concentration of 2.0 μM. The results indicated 2, 3, and 5 having meaningful reducing capacity of copper (I) ions concentration of 6.1-8.4 μM.     

Hyphae-Colonizing <Emphasis Type="Italic">Burkholderia</Emphasis> sp.—A New Source of Biological Control Agents Against Sheath Blight Disease (<Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG1-IA<Emphasis Type="Italic">)</Emphasis> in Rice

Sheath blight infection of rice by Rhizoctonia solani Kühn AG1-IA often results in serious yield losses in intensive rice cultivation. Biological control agents (BCAs) have previously been isolated but poor efficiency is often observed when applied under field conditions. This study compares a traditional dual-culture plate assay and a new water-surface microcosm assay for isolation of antagonistic soil bacteria. In the water-surface microcosm assay, floating pathogen mycelium is used as a source for isolation of hyphae-colonizing soil bacteria (HCSB), which are subsequently screened for antagonism. Ten antagonistic soil bacteria (ASB) isolated from a variety of Vietnamese rice soils using dual-culture plates were found to be affiliated with Bacillus based on 16S rRNA gene sequencing. However, all the ASB isolates grew poorly and showed no antagonism in the water-surface microcosm assay. In contrast, 11 (out of 13) HCSB isolates affiliated with Burkholderia sp. all grew well by colonizing the hyphae in the microcosms. Two of the Burkholderia sp. isolates, assigned to B. vietnamiensis based on recA gene sequencing, strongly inhibited fungal growth in both the dual-culture and water-surface microcosm assays; HCSB isolates affiliated to other species or species groups showed limited or no inhibition of R. solani in the microcosms. Our results suggest that HCSB obtained from floating pathogen hyphae can be a new source for isolation of efficient BCAs against R. solani, as the isolation assay mimics the natural habitat for fungal-bacterial interaction in the fields.     

IL-4-STAT6 signal transduction-dependent induction of the clinical phase of Sjögren's syndrome-like disease of the nonobese diabetic mouse

NOD.B10-H2(b) and NOD/LtJ mice manifest, respectively, many features of primary and secondary Sj?gren's syndrome (SjS), an autoimmune disease affecting primarily the salivary and lacrimal glands leading to xerostomia (dry mouth) and xerophthalmia (dry eyes). B lymphocytes play a central role in the onset of SjS with clinical manifestations dependent on the appearance of autoantibodies reactive to multiple components of acinar cells. Previous studies with NOD.IL4(-/-) and NOD.B10-H2(b).IL4(-/-) mice suggest that the Th2 cytokine, IL-4, plays a vital role in the development and onset of SjS-like disease in the NOD mouse model. To investigate the molecular mechanisms by which IL-4 controls SjS development, a Stat6 gene knockout mouse, NOD.B10-H2(b).C-Stat6(-/-), was constructed and its disease profile was defined and compared with that of NOD.B10-H2(b).C-Stat6(+/+) mice. As the NOD.B10-H2(b).C-Stat6(-/-) mice aged from 4 to 24 wk, they exhibited leukocyte infiltration of the exocrine glands, produced anti-nuclear autoantibodies, and showed loss and gain of saliva-associated proteolytic enzymes, similar to NOD.B10-H2(b).C-Stat6(+/+) mice. In contrast, NOD.B10-H2(b).C-Stat6(-/-) mice failed to develop glandular dysfunction, maintaining normal saliva flow rates. NOD.B10-H2(b).C-Stat6(-/-) mice were found to lack IgG1 isotype-specific anti-muscarinic acetylcholine type-3 receptor autoantibodies. Furthermore, the IgG fractions from NOD.B10-H2(b).C-Stat6(-/-) sera were unable to induce glandular dysfunction when injected into naive recipient C57BL/6 mice. NOD.B10-H2(b).C-Stat6(-/-) mice, like NOD.B10-H2(b).IL4(-/-) mice, are unable to synthesize IgG1 Abs, an observation that correlates with an inability to develop end-stage clinical SjS-like disease. These data imply a requirement for the IL-4/STAT6-pathway for onset of the clinical phase of SjS-like disease in the NOD mouse model.     

Unique burial practice by ancient cavemen of the Hoa Binh civilization in Vietnam

The discovery of a female skeleton is reported, which can be ascribed to the Hoa Binh civilization, existing about 10,000 years before now. The most remarkable fact concerning this finding is the existence of seashells (Cyprea arabica), which were found in the eye sockets. The reasons for this in Southeast Asia so far unique burial practice are discussed.     

Improvement of bioactive saponin accumulation in adventitious root cultures of Panax vietnamensis via culture periods and elicitation

Plant Cell, Tissue and Organ Culture (PCTOC) - The effects of l-alanine and its derivatives on cephalotaxine production of Cephalotaxus mannii suspension cultures were investigated in this paper....     

A novel electrochemically active and Fe(III)-reducing bacterium phylogenetically related to Aeromonas hydrophila,isolated from a microbial fuel cell

A facultative anaerobic bacterium was isolated from a mediator-less microbial fuel cell fed with artificial wastewater containing acetate and designated as PA3. The isolate was identified as a strain of Aeromonas hydrophila based on its biochemical, physiological and morphological characteristics as well as 16S rDNA sequence analysis and DNA-DNA hybridization. PA3 used glucose, glycerol, pyruvate and hydrogen to reduce Fe(III), nitrate and sulfate. Cyclic voltammetry showed that PA3 was electrochemically active and was the culture collection strain A. hydrophila KCTC 2358. Electricity was generated from a fuel cell-type reactor, the anode compartment of which was inoculated with cell suspensions of the isolate or A. hydrophila KCTC 2358. The electrochemical activities are novel characteristics of A. hydrophila.     

Local delivery of AAV2-CTLA4IgG decreases sialadenitis and improves gland function in the C57BL/6.NOD-Aec1Aec2 mouse model of Sjögren's syndrome

Introduction

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a key negative costimulatory molecule that displays a wide range of anti-inflammatory properties and is currently approved to treat rheumatoid arthritis as a recombinant fusion protein (CTLA4IgG). To better understand the role of CTLA4IgG in primary Sjögren's syndrome (pSS), we generated a recombinant adeno-associated virus vector serotype 2 (AAV2) expressing a chimera of mouse CTLA-4 fused with a human immunoglobulin (AAV2-CTLA4IgG) and observed the effect of this molecule in C57BL/6.NOD-Aec1Aec2 mice, an animal model of pSS.

Methods

A recombinant adeno-associated virus-2 (AAV-2) vector was constructed encoding a CTLA4IgG fusion protein. The AAV2-CTLA4IgG vector and an AAV2 control vector encoding beta galactosidase (LacZ) were administered by retrograde cannulation of the submandibular glands of C57BL/6.NOD-Aec1Aec2 mice. Protein expression was measured by ELISA and salivary glands were assessed for inflammation and activity.

Results

Recombinant CTLA4IgG blocked B7 expression on macrophages in vitro. In vivo, localized expression of CTLA4IgG in the salivary glands of C57BL/6.NOD-Aec1Aec2 mice inhibited the loss of salivary gland activity and decreased T and B cell infiltration as well as dendritic cells and macrophages in the glands compared with control mice. In addition a decrease in several proinflammatory cytokines and an increase in transforming growth factor beta-1 (TGF-β1) expression were also observed.

Conclusions

These data suggest expression of CTLA4IgG in the salivary gland can decrease the inflammation and improve the xerostomia reported in these mice.