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51.
The penicillin-binding protein (PBP) profiles of 33Clostridium perfringens and sixClostridium species isolated from clinically significant infections were analyzed. Three new PBPs—PBPs 2B, 4B, and 5B (84, 70, and 49 kDa respectively)—and a high-molecular-weight PBP 6 (45 kDa) were demonstrated in theC. perfringens isolates. In addition to PBPs 1 and 2, PBPs 2B and 4B were seen to show low binding affinities for penicillin, although further studies are required to determine their possible roles in the development of penicillin resistance. The PBP profiles of theC. perfringens isolates were complex. Variations in apparent molecular weights (M
r
s) of all PBPs, with the exception of PBP 5 and the presence or absence of PBPs 2, 3, and 4B, gave rise to nine different PBP patterns. The high-M
rPBPs 5 and 6, which exhibited high-penicillin-binding affinities, were with only one exception consistent within theC. perfringens isolates. These PBPs 5 and 6 of theC. perfringens isolates and independent PBPs found in the otherClostridium species studied indicate that PBP analysis may assist in the differentiation ofClostridium spacies. 相似文献
52.
Martine de Boer Maaike te Lintel Hekkert Jiang Chang Bibi S. van Thiel Leonie Martens Maxime M. Bos Marion G. J. de Kleijnen Yanto Ridwan Yanti Octavia Elza D. van Deel Lau A. Blonden Renata M. C. Brandt Sander Barnhoorn Paula K. Bautista-Niño Ilona Krabbendam-Peters Rianne Wolswinkel Banafsheh Arshi Mohsen Ghanbari Christian Kupatt Leon J. de Windt A. H. Jan Danser Ingrid van der Pluijm Carol Ann Remme Monika Stoll Joris Pothof Anton J. M. Roks Maryam Kavousi Jeroen Essers Jolanda van der Velden Jan H. J. Hoeijmakers Dirk J. Duncker 《Aging cell》2023,22(3):e13768
53.
A porcine glucosephosphate isomeraseprocessed pseudogene has been isolated and sequenced. The pseudogene has several base substitutions as well as an insertion and deletions, and is 83% homologous to the corresponding cDNA. It contains an intervening sequence of 565 bp, is truncated at the 3 end, and is flanked by direct repeats of seven nucleotides. Fluorescent in situ hybridization to porcine metaphase chromosomes localized the processed pseudogene to Chromosome (Chr) 1q1.6-1.7. A (GT)14(AT)15 microsatellite was detected close to the processed pseudogene. 相似文献
54.
Frans A. Prins Ronnie van Diemen-Steenvoorde Jan Bonnet Ingrid Cornelese-ten Velde 《Histochemistry and cell biology》1993,99(6):417-425
Reflection contrast microscopy (RCM) of ultrathin sections was recently introduced as a sensitive technique for visualization with enhanced definition in immunogold histochemistry. Experience of using RCM as a major tool in immunocytochemical research in different fields is summarized, e.g. oncology, nephrology and embryology. The sensitive visualization of immunocytochemical labels, gold particles or peroxidase-diaminobenzidine deposits in or on ultrathin sections, by RCM instead of electron microscopy is demonstrated. RCM of ultrathin sections is an adequate light microscopical alternative for immunoelectron microscopy, since an overview of both label and tissue is obtained with a high image definition and high contrast of label. In the studies presented, RCM is shown to provide a better gradation in staining intensity and staining pattern than other light microscopical methods. Moreover, a precise localization of multiple labels is obtained with this method. Besides the applications shown, ultrathin section visualization by RCM is very useful for correlative light- and electron microscopical studies of fine structures. Commercially available fluorescence microscopes can be adapted for proper RCM functioning; an adaptation scheme and list of microscopes tested is provided. 相似文献
55.
Dido Vassilacopoulou James A. Ripellino Nikolaos Tezapsidis Vivian Y. H. Hook Nikolaos K. Robakis 《Journal of neurochemistry》1995,64(5):2140-2146
Abstract: The amyloid β peptide (Aβ) of Alzheimer disease is derived from the proteolytic processing of the amyloid precursor proteins (APPs), which are considered type I transmembrane proteins. Here we report that the soluble fraction of isolated adrenal medullary chromaffin granules (CG), a model neuronal secretory vesicle system, contains an antigen that immunochemically and on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was indistinguishable from full-length APP. A truncated APP fragment with intact Aβ sequence was also detected in the soluble fraction of CG. In vitro experiments showed that full-length APP was solubilized from CG membranes at 37°C as a function of pH, with a peak of activity between pH 8.5 and pH 9.0. Solubilization of full-length APP was inhibited by several protease inhibitors, including aprotinin, cystatin, and iodoacetamide, by the divalent cations Ca2+ and Zn2+ , and by preheating of the membranes. These results are consistent with and suggest the involvement of an enzymatic mechanism in the solubilization of potentially amyloidogenic full-length APP. Production of Aβ from a transmembrane APP predicts a proteolytic cleavage within the lipid bilayer, a site relatively inaccessible to proteases. Thus, the detected soluble, potentially amyloidogenic, full-length APP may be a substrate for the proteases producing Aβ. The detection of soluble APP with intact Aβ sequence in secretory vesicles is consistent with the extracellular topology of amyloid depositions. 相似文献
56.
The relative uptake rates of N, P, K, S, Ca, Mg, Fe, Mn, Zn, Cu, and Al were estimated in beech seedlings pot cultured in the field in six acid soils (treatments). The relative uptake rates were compared with the relative growth rates. The relative uptake rates of N, K and Ca agreed well with the growth rates of the seedlings irrespective of widely differing soil conditions (acid sand-clayey till, pH 4–6). The relative uptake rates of P, Fe, and Al differed from that predicted by the growth rate. The uptake rates of Fe and Al were highest at the lowest growth rates, and the P uptake rate was lower than the growth rate in these treatments. Thus the P availability probably limited growth in an eluvial (E) horizon of a podzol, and possibly in the illuvial (B) horizon of a podzol and in an acid clayey till (Dystric Cambisol). Low P uptake was associated with a tendency towards higher relative root growth rates. In terms of the concept of steady state nutrition the high relative root growth rate in some treatments may be interpreted as an acclimation to low P supply. The P limitation seemed to be related to interactions among Fe, Al and organic compounds of the soil solution.FAX no: +4646104423 相似文献
57.
We conducted a set of in situ incubations to evaluate patterns of N availability among dominant land uses in the shortgrass
steppe region of Colorado, USA, and to assess recovery of soil fertility in abandoned fields. Replicated 30 d incubations
were performed in 3 sets of native (never cultivated), abandoned (cultivated until 1937), and currently cultivated, fallow
fields. Net N mineralization and the percentage of total N that was mineralized increased in the order: native, abandoned,
cultivated. Higher soil water content in fallow fields is the most likely reason for greater mineralization in cultivated
fields, while higher total organic C and C/N ratios in native and abandoned fields may explain differences in mineralization
between these land uses. Recovery of soil organic matter in abandoned fields appears to involve accumulation of soil C and
N under perennial plants, but probable methodological artifacts complicate evaluation of the role of individual plants in
recovery of N availability. Higher N mineralization and turnover in cultivated fields may make them more susceptible to N
losses; recovery of N cycling in abandoned fields appears to involve a return to slower N turnover and tighter N cycling similar
to native shortgrass steppe. 相似文献
58.
A mutator, mu2(a), in Drosophila melanogaster potentiates terminal deficiencies. In the female germ line the y mutant frequency induced by irradiation of mature oocytes with 5 Gy increases approximately twofold in heterozygotes and 20-fold in homozygotes compared with wild type. The recovery of terminal deficiencies is not limited to breaks close to chromosome ends; high frequencies of deficiencies can be recovered with breakpoints located in centric heterochromatin or near the middle of a chromosome arm. Lesions induced by γ-rays are repaired slowly in mu2(a) oocytes, but become ``fixed' as terminal deficiencies upon fertilization. A few lesions induced in wild-type females also produce terminal deficiencies. Mutator males do not exhibit an increase in terminal deletions, regardless of the germ cell stage irradiated. In addition, there is no increase in the mutant frequency when mature sperm are irradiated and fertilize eggs produced by mu2(a) females. The data are consistent with the hypothesis that lesions induced in sperm chromosomes are repaired after fertilization, while lesions induced in oocyte chromosomes are shunted instead to a mechanism that stabilizes broken chromosome ends. We propose that mu2 affects chromosomal structure during oogenesis, thereby modulating DNA repair. 相似文献
59.
Roman Bo?a Peter Baran L'ubor Dlháň Hartmut Fuess Wolfgang Haase Franz Renz Wolfgang Linert Ingrid Svoboda Rüdiger Werner 《Inorganica chimica acta》1997,260(2):4119-136
The structure of the [Fe(bzimpy)2](ClO4)2·xH2O system (x = 0.25) was determined by single crystal X-ray structure analysis. The Fe(II) ion is hexacoordinated by six donor nitrogen atoms. The magnetic properties of the complex were investigated by powder magnetic susceptibility measurements and ESR. The freshly prepared sample does not show any traces of iron(III) impurities but these are formed as a function of time. After 1 year the sample contains 8.2% iron(III) as shown by UV spectroscopy and indicated by geff = 4.3 and 2.0 in its ESR spectrum. This explains the recorded ξ versus T behaviour at low temperature: with increasing temperature the ξ value decreases according to the Curie-Weiss law for a S = 5/2 system having an effective g = 4.3. Above 220 K a continuous increase in the ξ value is observed and a spin crossover applies. The spin transition is not complete at room temperature. A pronounced hysteresis is observed upon heating/cooling the sample between 220 and 414 K on the basis of magnetic data and infrared spectra. 相似文献
60.
Liedtke Christa; Polsakiewicz Monika; Hartmann Ingrid; Peters Petra; Volkmann Dieter; Scherer Gnther F.E. 《Journal of experimental botany》1997,48(6):1215-1221
The vacuolar membrane, the tonoplast, is a proteinrich membranehitherto only few proteins in it have been identified. As anapproach for the identification of tonoplast proteins by monoclonalantibodies (MABs), purified tonoplast from cress roots (Lepidiumsativum L.) were used for immunization and plasma membranesas a control membrane to test the absence of antigen. The MABTOP 35 identified a glycoprotein of about 35 kDa in purifiedtonoplast of cress roots. Triton X-114 phase separation showedthat it was a hydrophobic integral membrane protein. In immunocytochemistrythe MAB TOP 35 strongly labelled the vacuolar membrane. Theabsence of cell wall or plasma membrane labelling by TOP 35indicates a distinct biosynthetic pathway of this protein tothe vacuolar membrane in plants. Key words: Immnocytochemistry, Lepidium sativum, monoclonal antibody, secretion, vacuole 相似文献