Detection of plasmid-mediated IMP-1 metallo-β-lactamase and quinolone resistance determinants in an ertapenem-resistant Enterobacter cloacae isolate

Objective: To investigate the mechanism of carbapenem resistance and the occurrence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in a clinical isolate of Enterobacter cloacae. Methods: An ertapenem-resistant E. cloacae ZY106, which was isolated from liquor puris of a female gastric cancer patient in a Chinese hospital, was investigated. Antibiotic susceptibilities were determined by agar dilution method. Conjugation experiments, isoelectric focusing, polymerase chain reaction (PCR), and DNA sequence analyses of plasmid-mediated carbapenemases and quinolone resistance determinants were preformed to confirm the genotype. Outer membrane proteins (OMPs) were examined by urea-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Urea-SDS-PAGE). Results: Minimum inhibitory concentrations (MCs) of imipenem, mer-openem, and ertapenem for ZY106 were 2,4, and 16 ug/ml, respectively. Conjugation studies with Escherichia coli resulted in the transfer of significantly reduced carbapenem susceptibility. ZY106 produced IMP-1 metallo-p-lactamase and CTX-M-3 extended-spectrum P-lactamase, and E. coli transconjugant produced IMP-1. Plasmid-mediated quinolone resistance determinant qnrSI was detected in ZY106. Transfer of the qnrSI-encoding-plasmid into E. coli by conjugation resulted in intermediate resistance to ciprofloxacin in E. coli transconjugant. Urea-SDS-PAGE analysis of OMPs showed that ZY106 lacked an OMP of approximately 38 KDa. Conclusion: It is the first IMP-1-producing Enterobacteriaceae in China and the first report of a clinical isolate that harbors both blaIMP and qnrS genes as well. The blaIMP-1, blaCTX-M-3, and qnrSl are encoded at three different plasmids. IMP-1 combined with the loss of an OMP possibly resulted in ertapenem resistance and reduced imipenem and mero-penem susceptibility in E. cloacae.     

改良的二维电泳法分离水稻小穗蛋白

介绍一种适于植物材料的二维电泳方法,并对其中各有关步骤进行了讨论。该方法特別适于含干扰等电聚焦,及含使背景显色杂质的植物材料的全蛋白分离,并可获得较高分辨率及稳定的二维电泳图谱。文中还利用这种二维电泳技术,比较了籼型广亲和水稻、籼稻,粳型广亲和水稻、粳稻小穗的蛋白质差异。     

水稻种子萌发过程中贮藏蛋白降解的研究概述

水稻种子贮藏蛋白分为水溶性清蛋白、醇溶性蛋白、盐溶性球蛋白和稀酸或稀碱溶性谷蛋白,其中以谷蛋白为主;水稻种子贮藏蛋白的降解与蛋白酶活性密切相关,它的降解过程受赤霉素、脱落酸、多效唑、茉莉酸甲酯等植物生长物质调控.     

论豆腐传统工艺的科学文化性

豆腐作坊的传统制作工艺虽然已延续了近千年,但在今天看来仍然不落后,而且包含着丰富的文化内涵。豆腐制作要经历选料、浸泡原料、磨浆、分离、煮浆过滤、点浆凝固和成型等一整套工序,每一道工序都有各自的讲究,包含着丰富的科学信息,是豆腐制作工艺经验的总结、传承与发展。     

川白芷胚胎发育时期蛋白质的动态变化

通过石蜡切片,汞-溴酚蓝染色,在显微镜下系统观察了川白芷胚胎发育时期蛋白质的动态变化.结果表明:在受精后1-16d,蛋白质积累逐渐增多,且胚细胞中的蛋白质含量的增加明显快于珠被;合点端细胞中蛋白质很明显,珠孔端蛋白质少于合点端;第17d后,胚和珠被的蛋白质含量逐渐下降.     

间歇性低氧运动对大鼠骨骼肌线粒体解偶联蛋白3（UCP3）表达的影响

目的：探讨间歇性低氧运动对肥胖及正常SD大鼠骨骼肌线粒体解偶联蛋白-3表达的影响。方法：将100只雄性健康大鼠随机分为正常对照组（40只）和肥胖造模组（60只），从造模成功的SD大鼠中挑选40只，随机分为肥胖常氧安静组（A组）、肥胖常氧运动组（B组）、肥胖低氧安静组（C组）和肥胖低氧运动组（D组）。正常对照组随机分为正常常氧安静组（E组）、正常常氧运动组（F组）、正常低氧运动组（G组）和正常低氧安静组（H组），每组10只。第4周末次运动后24h左右进行采样，采样前所有大鼠禁食过夜，取后肢骨骼肌匀浆提取线粒体，用western blot的方法测定肥胖大鼠以及正常组大鼠的骨骼肌线粒体UCP3的蛋白表达水平。结果：正常组大鼠骨骼肌线粒体UCP3蛋白表达明显高于造模组大鼠（P〈0．05）；低氧安静及运动组大鼠骨骼肌线粒体UCP3蛋白的表达均明显高于常氧安静组（P〈0．05）；低氧或运动对大鼠骨骼肌线粒体UCP3蛋白的表达的影响与大鼠的体脂百分比有呈负相关的趋势。结论：肥胖大鼠骨骼肌线粒体UCP3蛋白的表达低于正常大鼠，4周的有氧运动以及间歇性低氧刺激使骨骼肌线粒体UCP3蛋白的表达增加，运动与间歇性低氧刺激相结合能使骨骼肌线粒体UCP3的表达水平高于单一的运动或间歇性低氧刺激。而且，低氧刺激以及低氧刺激与运动相结合使得大鼠的体重、体脂百分比降低幅度比单一的运动更加明显。     

甘蔗糖蜜酒精发酵污染问题

在甘蔗糖蜜酒精生产中,由于杂菌污染而导致寄生发酵的现象普遍存在,严重时导致生产瘫痪。本文在对污染及其控制问题进行分析的基础上,指出控制污染的关键在于“抑菌”。     

线粒体解耦联蛋白(uncoupHng protein,UCP)与体内供热

综述了UCP(解耦联蛋白家族)的结构、功能及研究进展。     

A variant within the AQP1 3ʹ-untranslated region is associated with running performance,but not weight changes,during an Ironman Triathlon

The objective of this study was to test the association of the rs1049305 (G > C) variant within the 3?-untranslated region of the aquaporin 1 gene, AQP1, with changes in body weight, post-race serum sodium concentration and performance in Ironman triathletes. Five hundred and four male Ironman triathletes were genotyped for the rs1049305 variant within the AQP1 gene. Change in pre- and post-race body weight was calculated for 470 triathletes and used as a proxy for changes in body fluid during the race, as well as to divide triathletes into biologically relevant weight-loss groups (0–3%, 3–5% and >5%). There were no rs1049305 genotype effects on post-race serum sodium concentrations (P = 0.647), pre-race weight (P = 0.610) nor relative weight change during the Ironman Triathlons (P = 0.705). In addition, there were no significant differences in genotype (P = 0.640) nor allele (P = 0.643) distributions between the weight loss groups. However, triathletes who carry a C-allele were found to complete the 42.2-km run stage faster (mean 286, s = 49 min) than triathletes with a GG genotype (mean 296, s = 47 min; P = 0.032). The AQP1 rs1049305 variant is associated with running performance, but not relative body weight change, during the 2000, 2001 and 2006 South African Ironman Triathlons.     

Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system

BackgroundThe heterologous expression of parasitic proteins is challenging because the sequence composition often differs significantly from host preferences. However, the production of such proteins is important because they are potential drug targets and can be screened for interactions with new lead compounds. Here we compared two expression systems for the production of an active recombinant aldehyde dehydrogenase (SmALDH_312) from Schistosoma mansoni, which causes the neglected tropical disease schistosomiasis.ResultsWe produced SmALDH_312 successfully in the bacterium Escherichia coli and in the baculovirus expression vector system (BEVS). Both versions of the recombinant protein were found to be active in vitro, but the BEVS-derived enzyme showed 3.7-fold higher specific activity and was selected for further characterization. We investigated the influence of Mg²⁺, Ca²⁺ and Mn²⁺, and found out that the specific activity of the enzyme increased 1.5-fold in the presence of 0.5 mM Mg²⁺. Finally, we characterized the kinetic properties of the enzyme using a design-of-experiment approach, revealing optimal activity at pH 7.6 and 41°C.ConclusionsAlthough, E. coli has many advantages, such as rapid expression, high yields and low costs, this system was outperformed by BEVS for the production of a schistosome ALDH. BEVS therefore provides an opportunity for the expression and subsequent evaluation of schistosome enzymes as drug targets.How to cite: Harnischfeger J, Beutler M, Salzig D, et al. Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.08.002