Viet nam is known as an endemic area of melioidosis but its etiologic agent originated in Viet nam was not extensively studied. For the first time, we analyzed the cellular lipid and fatty acid compositions of 15 Vietnamese isolates of Burkholderia pseudomallei, 10 from humans and 5 from the environment. Cellular lipid compositions were analyzed by two-dimensional thin-layer chromatography on silica gel G plates. Cellular fatty acid methyl esters were analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major lipids in all the isolates were phosphatidylglycerol (PG), two forms of phosphatidylethanolamine (PE-1 and PE-2), and two forms of ornithine-containing lipid (OL-1 and OL-2). PE-1 contained non-hydroxy fatty acids at both sn-1 and -2 positions, while PE-2 possessed 2-hydroxy fatty acids and non-hydroxy fatty acids in a ratio of 1 : 1.Since snake venom phospholipase A2 digestion of PE-2 liberated 2-hydroxy fatty acids, it was confirmed that these acids are at the sn-2 position of glycerol moiety. In both OL-1 and OL-2, amide-linked fatty acid was 3-hydroxy palmitic acid (3-OH-C16 : 0), while ester-linked fatty acids were non-hydroxy acids in OL-1 and 2-hydroxy acids in OL-2. The total cellular fatty acid compositions of the test strains were characterized by the presence of 2-hydroxy palmitic (2-0H-C16 : 0), 2-hydroxy hexadecenoic (2-OH-C16 : 1), 2-hydroxy octadecenoic (2-0H-C18 : 1), 2-hydroxy methylene octadecanoic (2-0H-C19CPA), 3-hydroxy myristic (3-0H-C14 : 0) and 3-hydroxy palmitic (3-0H-C16 : 0) acids. There were significant differences in the concentration of hexadecenoic (C16 : 1), methylene hexadecanoic (C17CPA), octadecenoic (C18 : 1) and methylene octadecanoic (C19CPA) acids among the Vietnamese isolates of B. pseudomallei. However, no significant difference was observed in cellular lipid and fatty acid components between strains of human and environmental origins.
BackgroundCentrostachys aquatica is a perennial emergent macrophyte in marshy places and in rivers. The species was recorded in Senegal and Nigeria, but widespread in tropical Africa, and South and East Asia. Aqueous methanol extracts C. aquatica was found to be toxic to several plant species. However, no phytotoxic substance has been reported in this species. Therefore, we investigated phytotoxic activity and searched for phytotoxic substances with allelopathic activity in C. aquatica.ResultsAn aqueous methanol extract of C. aquatica inhibited the growth of roots and hypocotyls of cress (Lepidium sativum). The extract was then purified by several chromatographic runs and a phytotoxic substance with allelopathic activity was isolated and identified by spectral analysis as loliolide. Loliolide inhibited cress root and hypocotyl growth at concentrations greater than 0.03 μM. The concentrations required for 50% growth inhibition of cress roots and hypocotyls was 0.18 and 0.15 μM, respectively.ConclusionThese results suggest that loliolide is a phytotoxic substance and may contribute to the allelopathic effect caused by C. aquatica.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-014-0059-1) contains supplementary material, which is available to authorized users.
This paper investigates the correlation amongst transparency, accountability, corruption, and public administration performance in Vietnam using data from the Vietnam Provincial Governance and Public Administration Performance Index survey in 2012. The Generalised Canonical Analysis is applied to evaluate the meaning of the ‘Don’t Know’ answer which often exists in response to questions on perception of corruption. The results reveal that ‘Don’t Know’ implies corruption. The paper then, shows that a high level of transparency is accompanied with a low level of perception of corruption while impacts of accountability on corruption are mixed. Furthermore, corruption is a critical factor that deteriorates the administration performance whereas transparency and accountability are ineffective in being translated into the quality of administrative services. The results raise the need to closely examine the de-facto forms of transparency and accountability as well as the political will in the fight against corruption to improve the quality of public administrative services in Vietnam.
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