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101.
Stefan Evers Barbara Casadewall Murielle Charles Sylvie Dutka-Malen Marc Galimand Patrice Courvalin 《Journal of molecular evolution》1996,42(6):706-712
Thed-alanine:d-alanine-ligase-related enzymes can have three preferential substrate specificities. Usually, these enzymes synthesized-alanyl-d-alanine. In vancomycin-resistant Gram-positive bacteria, structurally related enzymes synthesized-alanyl-d-lactate or Dalanyl-d-serine. The sequence of internal fragments of eight structurald-alanine:d-alanine ligase genes from enterococci has been determined. Alignment of the deduced amino acid sequences with those of other
related enzymes from Gram-negative and Gram-positive bacteria revealed the presence of four distinct sequence patterns in
the putative substrate-binding sites, each correlating with specificity to a particular substrate (d-alanine:d-lactate ligases exhibited two patterns). Phylogenetic analysis showed different clusters. The enterococcal subtree was largely
superimposable on that derived from 16S rRNA sequences. In lactic acid bacteria, structural divergence due to differences
in substrate specificity was observed. Glycopeptide resistance proteins VanA and VanB, the VanC-type ligases, and Dd1A and
DdlB from enteric bacteria andHaemophilus influenzae constituted separate clusters.
Correspondence to: P. Courvalin 相似文献
102.
Barbara D. Hettinger-Smith Mark Leid Thomas F. Murray 《Journal of neurochemistry》1996,67(5):1921-1930
Abstract: Chronic treatment with the adenosine receptor antagonist caffeine evokes an up-regulation of A1 adenosine receptors and increased coupling of the receptor to G proteins in rat brain membranes. However, chronic agonist exposure has not been explored. Primary cultures of cerebellar granule cells were exposed chronically to A1 adenosine receptor agonists and antagonists. Exposure to the A1 adenosine receptor agonist N 6 -cyclopentyladenosine resulted in (1) a time- and concentration-dependent reduction in the density of receptors labeled by 1,3-[3 H]dipropyl-8-cyclopentylxanthine, (2) an enhanced ability of guanyl nucleotides to decrease the fraction of A1 adenosine receptor sites displaying high affinity for 2-chloroadenosine, and (3) a functional uncoupling of receptors from adenylyl cyclase (EC 4.6.1.1). The adenosine antagonists caffeine and 8- p -sulfophenyltheophylline produced alterations in A1 adenosine receptor homeostasis that were antipodal to those associated with agonist treatment. Antagonist exposure (1) increased the density of A1 adenosine receptors in cerebellar granule cell membranes, (2) blunted the effect of guanyl nucleotides on receptor coupling to G proteins, and (3) increased the functional coupling of receptors to adenylyl cyclase inhibition. Forskolin treatment of cerebellar granule cells did not affect receptor density, suggesting that cyclic AMP is not involved in the regulation of A1 adenosine receptor expression. 相似文献
103.
104.
Stefania Canino Barbara Nieri Laura Pistelli Amedeo Alpi Luigi De Bellis 《Physiologia plantarum》1996,98(1):13-19
The activity of NADP+ -dependent isocitrate dehydrogenase (ICDH, EC 1.1.1.42) was investigated during the post-germinative growth of cucumber ( Cucumis sativus L. cv. Marketmore) seedlings. Isoelectric focusing showed the presence of several isoenzymes, two of which represented 70–80% of the total NADP+ -ICDH activity in cotyledons of seedlings grown in the dark. They had pI values between 4.8 and 5.8. The isoenzyme with higher pI was purified to homogeneity by hydrophobic interaction, affinity, hydroxylapatite and anion exchange chromatography. The purified isoenzyme is a dimeric protein, consisting of two apparently identical 43-kDa subunits. It is specific for NADP+ , inhibited by ATP and by 2-oxoglutarate, whereas it is not inhibited by citrate, succinate, and glyoxylate. The data indicate that NADP+ -ICDH from cucumber is structurally similar to ICDHs from other plants, but it shows some peculiar biochemical characteristics. 相似文献
105.
Peter Salzer Gerhard Hebe Andreas Reith Barbara Zitterell-Haid Harald Stransky Katja Gaschler Achim Hager 《Planta》1996,198(1):118-126
Elicitors released from hyphae or cell walls of the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) Quél. induced in suspension-cultured cells of Picea abies (L.) Karst. a set of fast reactions: (i) an immediate efflux of Cl– into the medium, followed by a K+ efflux; (ii) an influx of Ca2+ (measured as accumulation of 45Ca2+ in the cells); (iii) a phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein (detectable by 4 min after elicitor application); (iv) an alkalinization of the medium, and (v) a transient synthesis of H2O2. The removal of extracellular Ca2+ by EGTA delayed the elicitor-induced alkalinization. A further reduction of this response could be achieved by TMB-8 an inhibitor of Ca2+ release from intracellular stores. Moreover, the inhibition of protein kinase activity by staurosporine prevented the extracellular alkalinization completely. However, the effectiveness of the elicitors in inducing the extracellular alkalinization was strongly impaired by constitutively secreted enzymes of spruce cells which cleaved the elicitors to inactive fragments. It is suggested that in ectomycorrhizae the efficacy of elicitors released from fungal cell walls is controlled by apoplastic enzymes of the host; the plant itself is able to reduce the activity of fungal elicitors on their way through the plant cell wall. But those elicitors which finally reach the plasma membrane of host cells induce reactions that are similar to the early defense reactions in plant-pathogen interactions.Abbreviations DW
dry weight
- FW
fresh weight
- TMB-8
3,4,5 trimethoxybenzoic acid 8-(diethylamino)-octyl ester
We thank Prof. M. Zenk (Universität München, Germany) for providing spruce cell cultures, and Dr. I. Kottke (Universität Tübingen, Germany) for isolates of Hebeloma crustuliniforme Tü 704. We are also thankful to Dr. W. Mayer (Universität Tübingen) for valuble discussions. This work was supported by Deutsche Forschungsgemeinschaft. B. Zitterell-Haid was financed by Graduiertenkolleg Interaktion in Waldökosystemen (supported by Deutsche Forschungsgemeinschaft) and G. Hebe by a scholarship of the Landesgraduiertenförderungsgesetz. 相似文献
106.
Robert N. Fontaine Ruanna E. Gossett Friedhelm Schroeder Barbara A. O'Toole Thomas Doetschman Ann B. Kier 《Molecular and cellular biochemistry》1996,159(2):149-153
The effect of transforming growth factor beta-1 (TGF1) expression on fatty acid binding proteins was examined in control and two strains of gene targeted TGF1-deficient mice. Homozygous TGF1-deficient 129 × CF-1, expressing multifocal inflammatory syndrome, had 25% less liver fatty acid binding protein (L-FABP) when compared to control mice. The decrease in L-FABP expression was not due to multifocal inflammatory syndrome since homozygous TGF1-deficient/immunodeficient C3H mice on a SLID background had 36% lower liver L-FABP than controls. This effect was developmentally related and specific to liver, but not the proximal intestine, where L-FABP is also expressed. Finally, the proximal intestine also expresses intestinal-FABP (1-FABP) which decreased 3-fold in the TGF1-deficient/immunodeficient C3H mice only. Thus, TGF1 appears to regulate the expression of L-FABP and I-FABP in the liver and the proximal intestine, respectively.Abbreviations L-FABP
liver fatty acid binding protein
- I-FABP
intestinal fatty acid binding protein
- TGF1
transforming growth factor beta-1
- TNF-
tumor necrosis factor-
- MIP-
macrophage inflammatory protein-
- PMSF
phenylmethyl sulfonyl fluoride
- PBS
phosphate buffered saline 相似文献
107.
Kailash Prasad Victor A. Laxdal Ming Yu Barbara L. Raney 《Molecular and cellular biochemistry》1996,165(1):55-63
While antibiotics are broadly used in dental and medical therapy, little attention has been directed towards the potential toxic side effects of antibiotics on tissue regeneration. Here we examined the effect of a quinolone antibiotic, pefloxacin (Rhone Poulenc) on rat parotid gland responses to chronic isoproterenol treatment. Groups of rats received injections of isoproterenol to induce glandular growth, saline (controls), pefloxacin, or isoproterenol and pefloxacin in combination. Parotid gland weight decreased significantly after pefloxacin treatment for 7 days as well as inhibiting glandular enlargement provoked by isoproterenol. The same trend was observed for the rates of DNA synthesis, with the incorporation of [3H]-thymidine in isoproterenol/pefloxacin-treated rats reduced to 49% of isoproterenol treatment alone levels. Saline-treated animals were 42% of the rate of [3H]-thymidine incorporation into DNA observed in isoproterenol treated rats. While isoproterenol treatment increased steady-state mRNA levels for fos, jun, myc, src, c-erbB-2, ras and topo II, inclusion of pefloxacin with the isoproterenol regimen blocked these increases. Pefloxacin treatment by itself did not alter proto-oncogene mRNA levels in the parotid gland. Glandular amylase activity was decreased in the pefloxacin treated group, while the combination of isoproterenol with pefloxacin did not decrease glandular amylase levels to the extent of that observed with -agonist treatment alone. In acute experiments, pefloxacin significantly decreased the volume of saliva secreted by the parotid gland. These results suggest that quinolone-based antibiotics disturb the secretory function of the parotid gland and can inhibit cell proliferation and regeneration. (Mol Cell Biochem 165: 55–63, 1996) 相似文献
108.
John B. Kerrison Vronique J. Arnould M. Michael Barmada Robert K. Koenekoop Barbara J. Schmeckpeper Irene H. Maumenee 《Genomics》1996,33(3):523
Congenital nystagmus is an idiopathic disorder characterized by bilateral ocular oscillations usually manifest during infancy. Vision is typically decreased due to slippage of images across the fovea. As such, visual acuity correlates with nystagmus intensity, which is the amplitude and frequency of eye movements at a given position of gaze. X-linked, autosomal dominant, and autosomal recessive pedigrees have been described, but no mapping studies have been published. We recently described a large pedigree with autosomal dominant congenital nystagmus. A genome-wide search resulted in six markers on 6p linked by two-point analysis at θ = 0 (D6S459, D6S452, D6S465, FTHP1, D6S257, D6S430). Haplotype analysis localizes the gene for autosomal dominant congenital motor nystagmus to an 18-cM region between D6S271 and D6S455. 相似文献
109.
110.
Stuart L. Myers Richard Turnage Kevin Kadesky Lori Bartula Angela Riva Barbara Kalley-Taylor 《Prostaglandins & other lipid mediators》1995,50(1)
This study examines the hypothesis that PAF stimulates release of PGI2 from inflamed rabbit gallbladder explant cell cultures. New Zealand white rabbits underwent bile duct ligation for 72 h (72 h BDL), or sham operation, Sham and 72 h BDL gallbladder explants were placed in culture, and the cells grown to 75% confluence. The cells were exposed to increasing concentrations of PAF for 60 min. The media analyzed for eicosanoid release by EIA and the cells analyzed for cyclooxygenase and prostacyclin synthase content by immunoblot analysis. PAF increased release of 6-keto-PGF1α from the 72 h BDL gallbladder cell cultures in a dose-related manner which was inhibited by indomethacin preincubation by 90%. The increased 72 h BDL cell release of 6-keto-PGF1α was not associated with changes in the content of cyclooxygenase or prostacyclin synthase. PAF did not alter eicosanoid release from sham control cell cultures. These data suggest that PAF can only up-regulate endogenous 6-keto-PGF1α release from the 72 h BDL cells that had been previously stimulated by inflammation. PAF may thus contribute to gallbladder distention and injury by chronic stimulation of inflamed gallbladder PGI2 release. 相似文献