Protein synthesis in dorsal and ventral regions of Xenopus laevis embryos in relation to dorsal and ventral differentiation

Two-dimensional gel electrophoresis has been used to analyze protein synthesis in dorsal and ventral regions in embryonic stages of Xenopus laevis. Proteins specific either to dorsal or to ventral regions are synthesized for the first time at gastrulation, concomitant with morphological differentiation. The reliability of these proteins as markers of dorsal and ventral differentiation was tested by examining their synthesis in Uv-irradiated embryos, which have severely reduced capacity for dorsal development, reflected in reduced levels of the neuromuscular-specific enzyme acetylcholinesterase, but which continue to synthesize the great majority of proteins at normal rates. Synthesis of dorsal indicator proteins should be reduced or absent in these embryos, whereas ventral indicators should be synthesized at least to the same extent as in control embryos. Some of the putative dorsal and ventral indicators failed this test, but the majority were confirmed as reliable markers of dorsal and ventral differentiation, thus providing a connection between morphology and gene expression in the establishment of the dorsal-ventral axis in X. laevis.     

Cometabolic turnover of aniline,phenol and some of their monochlorinated derivatives by the Rhodococcus mutant strain AM 144

One-step conversion of aniline, phenol and some of their monochlorinated derivatives into the corresponding catechols by resting pre-adapted cells of the Rhodococcus mutant strain AM 144 (defective in synthesis of catechol 1,2-dioxygenase) was shown to depend on the availability of an additional metabolizable carbon substrate, e.g. glucose or acetate. A stoichiometric relation existed between the amount of the latter compounds added and the amount of aniline (or phenol, respectively) converted into catechol suggesting that the primary function of the cosubstrates was to provide reducing power to the oxygenative transformation reaction. The observed cosubstrate-dependence generally parallels that seen in previous studies on turnover of different monochloroaromatic non-growth substrates by aromatics-utilizing Rhodococcus wildtype-strains. Cell cultures of strain AM 144 growing at the expense of acetate also proved able to convert aniline into catechol. Typically, growth of the cells was retarded during the phase of aniline transformation as compared to the respective control cultures. Based on the results of these model experiments, it was concluded that (i) in natural microbial communities cometabolically active bacteria would hardly enrich under cometabolic conditions over fast-growing non-cometabolizing bacteria if the latter organisms will tolerate the particular non-growth substrate, and (ii) cometabolizing bacteria would have a selective advantage only if the non-growth substrate to be transformed is a toxic one or if it can serve as a potential nutrient source (e.g., of nitrogen or sulfur).Abbreviations MCA monochloroaniline - MCP monochlorophenol - MCC monochlorocatechol - TLC thin-layer chromatography - MS mass spectrometry - GLC gas-liquid chromatography - UV ultraviolet (range of the spectrum)     

Leaf and tepal anatomy, plastid ultrastructure and chlorophyll content in Galanthus nivalis L. and Leucojum aestivum L.

The leaf structure of Galanthus nivalis L. (snowdrop) and Leucojum aestivum L. (snowflake) is characterized by a homogeneous mesophyll tissue. The dominant characters of the leaves are cavities with mucose substance. There is a striking difference between these plants tepal anatomy. A central cavity occurs only in snowdrop tepals. Plastids from white parts of the tepals have a poorly developed membrane system. Leaves and green parts of tepals of both species possess amoeboid chloroplasts and contain chlorophyll a and b. The chlorophyll content in tepals is lower than in leaves, but the chlorophyll a:b ratio is always 2:1. Both, snowdrop and snowflake are from the family Amaryllidaceae, but their ecology is different. This paper presents common features related to systematic relatedness and differences induced by ecological factors.     

Studies on the possible biological effects of 50 Hz electric and/or magnetic fields: Evaluation of some glycolytic enzymes,glycolytic flux,energy and oxido-reductive potentials in human erythrocytes exposed in vitro to power frequency fields

An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione levels. all of which are biochemical parameters significant to erythrocyte function. Cells exposed to individual or superimposed EMFs have not shown any significant difference compared with the controls. © 1993 Wiley-Liss. Inc.     

Isolation and characterization of catechol oxidase from Solanum melongena

Catechol oxidase was distributed in soluble and particulate fractions of Solanum melongena. The purified preparation appears to be homogeneous by polyacrylamide gel electrophoresis. The enzyme shows two pH maxima—with catechol, 6.5 and 7.5; and with dopa, 6.5 and 7.9. The latent form of the enzyme does not occur in S. melongena. The preparation resembles the enzyme from other sources in substrate specificity towards various mono- and diphenols, having a higher affinity for catechol than dopa; this tendency increases on purification. The cresolase activity decreases with purification and a lag period with p-cresol is observed. The oxidation of mono- and diphenols is inhibited by ascorbic acid, sulphydryl compounds and chelating agents.     

Fine structural studies of rat adrenal cortices following prostaglandin administration

Summary Histological and fine structural studies of adrenal cortices were performed on male Sprague-Dawley rats which had been given intravenous injections of prostaglandin E₁ or E₂. It was found that there were increased numbers of intracellular lipid droplets, free ribonucleoprotein particles, cholesterol ester clefts and coated vesicles of both the small and large varieties. A reorganization of the internal mitochondrial membranes and the appearance of protrusions of parenchymal cytoplasm into the sinusoidal lumina accompanied by vasodilation were also observed. These alterations are not typical of those observed following exogenous ACTH administration and are therefore considered to be prostaglandin-induced. Supported in part by N.I.H. Grant AM-09561.     

Enhancing Data Reliability in TOMAHAQ for Large‐Scale Protein Quantification

The analytical scale of most mass‐spectrometry‐based targeted proteomics assays is usually limited by assay performance and instrument utilization. A recently introduced method, called triggered by offset, multiplexed, accurate mass, high resolution, and absolute quantitation (TOMAHAQ), combines both peptide and sample multiplexing to simultaneously improve analytical scale and quantitative performance. In the present work, critical technical requirements and data analysis considerations for successful implementation of the TOMAHAQ technique based on the study of a total of 185 target peptides across over 200 clinical plasma samples are discussed. Importantly, it is observed that significant interference originate from the TMTzero reporter ion used for the synthetic trigger peptides. This interference is not expected because only TMT10plex reporter ions from the target peptides should be observed under typical TOMAHAQ conditions. In order to unlock the great promise of the technique for high throughput quantification, here a post‐acquisition data correction strategy to deconvolute the reporter ion superposition and recover reliable data is proposed.     

桔黄赛多孢菌胞外胰蛋白酶的酶学特性

桔黄赛多孢菌Scedosporium aurantiacum是慢性肺病患者的常见呼吸道定植菌,在免疫缺陷人群中可引起侵袭性感染,致死率高,但由于致病机理不明,目前仍然缺乏有效的防控手段。我们在前期研究中,通过差异蛋白组学及酶工程技术发现分泌胰蛋白酶是桔黄赛多孢菌的潜在毒力因子,目前对这种蛋白酶的遗传信息、结构及致病机制并不清楚。本研究用Superdex S-200分子筛和DEAE-Sepharose离子交换两种填料将这种蛋白酶分离纯化出来,通过酶谱验证了纯化效果。进一步研究发现,这种胰蛋白酶对bFSR、bLSTR和bEKK 3种底物的水解性能最佳,对zFR和bzLR的水解性能最差。酶解最快的反应所对应的K_m为6.09μmol/L,V_max为13.01μmol/L/s,K_cat为23.65/s;酶解最慢的反应所对应的K_m为29.94μmol/L,V_max为11.35μmol/L/s,K_cat为20.63/s。研究结果对于填补赛多孢菌毒力因子研究的空白、针对毒力因子开发新型的抗真菌药物和治疗方法都具有重要意义。     

Lipophilic 9,10‐Dehydrofukinone Action on Pathogenic and Non‐Pathogenic Bacterial Biofilms. Why Is This Main Volatile Metabolite in Senecio?

The effect of a natural sesquiterpene ketone, 9,10‐dehydrofukinone (DHF), on pathogenic Staphylococcus aureus and Pseudomonas aeruginosa strains isolated from chronic infectious processes, was the focus of the present study. Lipophilic DHF produced important antibacterial synergistic effects in association with ciprofloxacin (CPX) against two biofilm‐forming strains of S. aureus HT1 (FIC=0.21) and P. aeruginosa HT5 (FIC=0.05). Hence, this mixture constitutes an excellent strategy to combat these biofilm‐producing bacteria that overexpress drug efflux pumps as a resistance mechanism. Additionally, a substantial rise in beneficial Lactobacillus biofilm biomass was determined as a very significant finding of this association. Particularly, a non‐pathogenic biofilm increment of 119 % was quantified when the mixture was added to a probiotic L. acidophilus ATCC SD‐5212 culture. A surface activity enhanced in 71 % with respect to untreated L. acidophilus culture was also generated by the DHF and CPX association, and therefore, a glycoprotein synthesis induction mediated by the mixture is discussed. The results obtained could help in the development of new selective antibiotics. From an ecological standpoint, the present study strongly suggests that DHF is a polyfunctional organic molecule produced with a high yield in Senecio punae that exerts a positive impact on a non‐pathogenic plant bacterium L. plantarum CE105.