摘要： The unusual and complex cell wall of pathogenic mycobacteria plays a major role in pathogenesis, with specific complex lipids acting as defensive, offensive, or adaptive effectors of virulence. The phthiocerol and phthiodiolone dimycocerosate esters (PDIMs) comprise one such category of virulence-enhancing lipids. Recent work in several laboratories has established that the Mycobacterium tuberculosis fadD26-mmpL7 (Rv2930-Rv2942) locus plays a major role in PDIM biosynthesis and secretion and that PDIM is required for virulence. Here we describe two independent transposon mutants (WAg533 and WAg537) of Mycobacterium bovis, both of which carry an insertion in Mb0100 (= M. tuberculosis Rv0097) to reveal a new locus involved in PDIM biosynthesis. The mutations have a polar effect on expression of the downstream genes Mb0101, Mb0102 (fadD10), Mb0103, and Mb0104 (nrp), and Mb0100 is shown to be in an operon comprising these genes and Mb0099. Reverse transcription-PCR analysis shows elevated transcription of genes in the operon upstream from the transposon insertion sites in both mutants. Both mutants have altered colony morphology and do not synthesize PDIMs or glycosylphenol-PDIM. Both mutants are avirulent in a guinea pig model of tuberculosis, and when tested as a vaccine, WAg533 conferred protective immunity against M. bovis infection at least equal to that afforded by M. bovis bacillus Calmette-Guerin.

关键词： Mycobacterium leprae   Schwann cell   laminin-2 molecule   PDIM   antibacterial therapy  

摘要： A recent study has demonstrated that the species-specific phenolic glycolipid of Mycobacterium leprae triggers uptake into Schwann cells by interaction with laminin-2 and the alpha -dystroglycan receptor. This finding emphasizes the importance of lipids in the biology of mycobacterial infection and suggests possible strategies to combat nerve damage in leprosy.

关键词： Mycobacterium bovis   PGL   PDIM   diagnosis-bacteria  

摘要： Sixteen Mycobacterium bovis (M. bovis) strains isolated from bovine tissues and one standard reference strain of M. bovis AN5 alongwith other species of mycobacteria for comparison were investigated for the presence of phenolic glycolipid (PGL) and phthiocerol dimycocerosate (PDIM) for rapid identification of M. bovis by thin-layer chromatography (TLC). The study indicated presence of PGL with an Rf value of 0.75 in chloroform-methanol solvent in all 17 M. bovis strains. The dimycocerostate A corresponding to spot A was the major constituent among all the three spots in M. bovis strains. TLC appeared to be a promising alternative to conventional biochemical methods for identification of M. bovis taking into consideration bath PGL and PDIM lipids. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： 调压器   多功能集成   涡轮式   调压计量站   涡轮流量计   调压站   止回阀   解决方法   固有特性   研究中心  

摘要： 调压计量站的结构,至今已做过多种尝试,原因是必须综合考虑技术、经济、规章制度和环保方面的种种限制,从而使它成为一个非常紧凑、但不影响其组成的固有特性的装置。PDIM 涡轮式多功能集成调压器,是法国煤气公司研究中心与一家法国企业 CD GAZ 密切合作的成果,是一种具有开创性的解决方法。

关键词： corrosion   iron, Fe  

摘要： It is demonstrated that PDIM imaging allows the observation of localized electrochemical reactions with subnanoscopic vertical resolution.

关键词： Phthiocerol dimycocerosate   PDIM   Phenolic glycolipid   PGL-I   Phosphatidyl inositol mannoside   PIM   Mycolates   Leprosy skin biopsies  

摘要： Lipids were extracted from small skin biopsies obtained from 5 lepromatous leprosy patients by employing a procedure designed to produce separate non-polar and polar fractions. The defatted tissue was subjected to alkaline hydrolysis and the total fatty acids in the hydrolysate were converted to methyl esters by a phase transfer reaction using iodomethane. The composition of free lipids and methyl esters of fatty acids was analysed by special thin-layer chromatographic systems. The presence of dimycocerosates of phthiocerol A, phthiocerol B and phthiodiolone A, phenolic glycolipid-I, two phosphatidyl inositol mannosides and 2 mycolates − alpha- and keto-mycolate − was demonstrated using reference lipid samples.