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1.
Summary -Hydroxybutyric acid (GHB) is a natural compound of mammalian brain synthesized from GABA. The characteristics of its synthesis, transport, release, distribution and turnover, in addition to the presence of a high affinity binding site for this substance in brain are in favor of a modulator role for GHB. The effects of hydrolytic enzymes on the specific binding capacity of GHB have been studied in the present work. Phospholipases A2 and C, neuraminidase and Pronase markedly decrease GHB binding to crude synaptosomal membranes from rat brain. This effect is time and enzyme concentration dependent. Trypsin, under the conditions employed, is less active. The inhibitory effects of phospholipases is correlated with phospholipid hydrolysis. Lysophospholipids, in the absence of bovine fatty acid free serum albumin partially inhibit GHB binding. The action of neuraminidase has been followed by sialic acid release and modifications of the ganglioside profile. The effects of phospholipase C and of neuraminidase are completely different to those on GABA binding sites. These results represent further data concerning the molecular existence of specific GHB binding sites on rat brain membranes.Abbreviations GHB -hydroxybutyrate - LPC L--lysophosphatidylcholine - LPE Lysophosphatidylethanolamine - PC Phosphatidylcholine - PE Phosphatidylethanolamine - BSA Bovine Serum Albumin  相似文献   
2.
Summary The effect of Triton X-100 on the activities of acid phosphatases from wheat germ, potato and human prostate was tested using -glycerophosphate, p-nitro-phenyl phosphate and naphthol AS BI phosphate as substrates. There was little effect on -glycerophosphatase activity at the concentrations of Triton X-100 tested. However at low concen trations of the detergent there was a stimulation of the activities of p-nitrophenyl phosphatase and naphthol phosphatase which were inhibited with the higher concentrations. Triton X-100 was found to enhance colour production between naphthol AS BI and fast red violet LB.Further evidence is presented confirming the presence of more than one acid phosphatase from each of the sources employed.  相似文献   
3.
Uptake,accumulation and metabolism of auxins in tobacco leaf protoplasts   总被引:2,自引:0,他引:2  
Uptake and metabolism of exogenous naphthalene-1-acetic acid (NAA) and indole-3-acetic acid (IAA) have been studied in tobacco (Nicotiana tabacum L. cv. Xanthi) mesophyll protoplasts. Both auxins entered protoplasts by diffusion under the action of the transmembrane pH gradient without any detectable participation of an influx carrier. Molecules were accumulated by an anion-trapping mechanism and most of them were metabolized within hours, essentially as glucose-ester and amino-acid conjugates. Protoplasts were equipped with a functional auxin-efflux carrier as evidenced by the inhibitory effect of naphthylphtalamic acid on IAA efflux. Basically, similar mechanisms of NAA and IAA uptake occurred in protoplasts. However, the two auxins differed in their levels of accumulation, due to different membrane-transport characteristics, and the nature of the metabolites produced. This shows the need to estimate the accumulation and the metabolism of auxins when analyzing their effects in a given cell system. The internal auxin concentration could be modulated by changing the transmembrane pH gradient, giving an interesting perspective for discriminating between the effects of intra- and extracellular auxin on physiological processes.Abbreviations BA benzoic acid - Ci/Ce accumulation ratio of auxin - IAAasp N-[3-indolylacetyl]-dl-aspartic acid - NAA naphthalene-1-acetic acid - NAAasp N-[1-naphthylacetyl]-l-aspartic acid - NPA N-1-naphthylphthalamic acid The authors thank Dr. M. Caboche (I.N.R.A, Versailles, France) for his generous gifts of some amide derivatives of 1-NAA, Mr. P. Varennes and Dr. B. Das (I.C.S.N., C.N.R.S., Gif-sur-Yvette, France) for recording and interpreting the mass spectra of NAA glucose ester, and Prof. P. Manigault (Institut des Sciences Végétales, Gif-sur-Yvette) for microscopy measurements of protoplast dimensions. This work was supported by funds from the C.N.R.S, I.N.R.A, and E.E.C.  相似文献   
4.
Characterization of lamin proteins in BHK cells   总被引:5,自引:0,他引:5  
Lamins are structural proteins found in rat liver nuclear envelope and are major constituents of the nuclear matrix. 2-D gel electrophoresis indicates that BHK cell nuclear matrix is composed of four major proteins (62 kD, 68 kD, 70 kD and 72 kD). Three of these proteins are very similar to lamins A, B and C of rat liver nuclear envelope according to their molecular mass and isoelectric points. An anti-serum specific to BHK matrix proteins has been raised. On 2-D immunoblot, this serum detects all the 62, 68 and 72 kD polypeptide isovariants but only one of the two isovariants of the 70 kD polypeptide. Rat lamins A, B and C react with the anti-BHK matrix serum. However, when a monoclonal antibody to rat liver lamins A, B and C is used (Burke, B, Tooze, J & Warren, G, EMBO j 2 (1983) 361 [23]), only the 72 kD (lamin A-like) and the 62 kD (lamin C-like) BHK polypeptides are detected. Our results suggest that although a strong similarity exists between BHK and rat lamins, there is no identical cross-reactivity between the two species.  相似文献   
5.
This study shows, by means of autoradiography, that RNA polymerase I activity is present in some of the nuclei isolated from Xenopus blastulae. This activity is localized in one or two nucleoli which have a diameter of at least 1.5 μm. The ratio between nucleolar and total nuclear grain counts allows a quantitative estimation of RNA polymerase I activity relative to total RNA polymerase activity at the blastula stage.  相似文献   
6.
Inoculation of leguminous seeds with selected rhizobial strains is practised in agriculture to ameliorate the plant yield by enhanced root nodulation and nitrogen uptake of the plant. However, effective symbiosis between legumes and rhizobia does not only depend on the capacity of nitrogen fixation but also on the entire nitrogen turnover in the rhizosphere. We investigated the influence of seed inoculation with two indigenous Sinorhizobium meliloti strains exhibiting different efficiency concerning plant growth promotion on nitrogen turnover processes in the rhizosphere during the growth of alfalfa. Quantification of six target genes (bacterial amoA, nirK, nirS, nosZ, nifH and archaeal amoA) within the nitrogen cycle was performed in rhizosphere samples before nodule formation, at bud development and at the late flowering stage. The results clearly demonstrated that effectiveness of rhizobial inocula is related to abundance of nifH genes in the late flowering phase of alfalfa. Moreover, other genes involved in nitrogen turnover had been affected by the inocula, e.g. higher numbers of amoA copies were observed during flowering when the more effective strain had been inoculated. However, the respective gene abundances differed overall to a greater extent between the three plant development stages than between the inoculation variants.  相似文献   
7.
The levels of total of IgG, IgG1, IgG2, IgG3 and IgG4 were evaluated in 54 patients with chronic paracoccidioidomycosis (PCM) before, during and after treatment using an enzyme-linked immunosorbent assay with Mexo and recombinant Pb27 (rPb27) as the antigens. Mexo was effective in distinguishing PCM patients from individuals in the negative control group (NC) based on total IgG and rPb27 performed worse than Mexo when these two groups were compared. IgG1, IgG2, IgG3 and IgG4 could not be used to clearly distinguish PCM patients from those in the NC group using either antigen. There was no clear relationship between antibody levels and the period of treatment. The majority of patients presented with decreased antibody levels during treatment, with no statistically significant differences among the different periods of treatment. Only IgG4 presented a negative correlation between its levels and clinical improvement during treatment. In total, 65% of untreated PCM patients showed reactivity against IgG4 when the Mexo antigen was used and this reactivity decreased over the course of treatment. There was a tendency towards decreasing antibody levels during treatment, but these antibody levels did not necessarily clear after the treatment was stopped. Mexo was useful for PCM diagnosis using total IgG; however, more studies are necessary before this antigen can be used in measuring the levels of total IgG and its subclasses for monitoring patients during treatment.  相似文献   
8.
9.
Magnetotactic bacteria (MTB) comprise a group of motile microorganisms common in most mesothermal aquatic habitats with pH values around neutrality. However, during the last two decades, a number of MTB from extreme environments have been characterized including: cultured alkaliphilic strains belonging to the Deltaproteobacteria class of the Proteobacteria phylum; uncultured moderately thermophilic strains belonging to the Nitrospirae phylum; cultured and uncultured moderately halophilic or strongly halotolerant bacteria affiliated with the Deltaproteobacteria and Gammaproteobacteria classes and an uncultured psychrophilic species belonging to the Alphaproteobacteria class. Here, we used culture‐independent techniques to characterize MTB from an acidic freshwater lagoon in Brazil (pH ~ 4.4). MTB morphotypes found in this acidic lagoon included cocci, rods, spirilla and vibrioid cells. Magnetite (Fe3O4) was the only mineral identified in magnetosomes of these MTB while magnetite magnetosome crystal morphologies within the different MTB cells included cuboctahedral (present in spirilla), elongated prismatic (present in cocci and vibrios) and bullet‐shaped (present in rod‐shaped cells). Intracellular pH measurements using fluorescent dyes showed that the cytoplasmic pH was close to neutral in most MTB cells and acidic in some intracellular granules. Based on 16S rRNA gene phylogenetic analyses, some of the retrieved gene sequences belonged to the genus Herbaspirillum within the Betaproteobacteria class of the Proteobacteria phylum. Fluorescent in situ hybridization using a Herbaspirillum‐specific probe hybridized with vibrioid MTB in magnetically‐enriched samples. Transmission electron microscopy of the Herbaspirillum‐like MTB revealed the presence of many intracellular granules and a single chain of elongated prismatic magnetite magnetosomes. Diverse populations of MTB have not seemed to have been described in detail in an acid environment. In addition, this is the first report of an MTB phylogenetically affiliated with Betaproteobacteria class.  相似文献   
10.
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