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11.
Jacqueline Goffart-Roskam 《Antonie van Leeuwenhoek》1965,31(1):249-261
Infection of a culture ofStaphylococcus aureus by a phage left more surviving colony-forming, sensitive bacteria than might be expected from the calculation of Po according to the Poisson distribution. The discrepancy could at least partly be explained by the heterogeneity in surface area of the colony-forming units before infection. The ratio lysogens/lysed cells shows a tendency to decrease when multiplicity is increased from 6 to 130.The experiments stress the influence of the bacterial density on the adsorption rate constant of the bacteriophage.Single step growth curve experiments gave low burst size values. The latent period was about 30 min. The stationary period began 45 to 50 min after infection. 相似文献
12.
Studies on the Formation of 6-Hydroxydopamine in Mouse Brain After Administration of 2,4,5-Trihydroxyphenylalanine (6-HydroxyDOPA) 总被引:1,自引:1,他引:0
2,4,5-Trihydroxyphenylalanine (6-OH-DOPA) destroys central and peripheral noradrenergic neurons, while sparing dopaminergic neurons. Previous studies indicate that 6-OH-DOPA toxicity is mediated by the formation of 6-hydroxydopamine. However, levels of 6-hydroxydopamine in brain following peripheral administration of 6-OH-DOPA have not been documented. In the current study, 6-OH-DOPA and 6-hydroxydopamine were measured in brain by HPLC with electrochemical detection after intraperitoneal injection of 6-OH-DOPA. When mice were injected with 100 mg 6-OH-DOPA/kg, 6-hydroxydopamine levels in the striatum were highest (1.9 microgram/g) at 15 min and fell slowly to 24% of the peak value at 4 h. Experiments with reserpine indicated that the relatively stability of 6-hydroxydopamine was largely dependent upon storage in synaptic vesicles. Reserpine (10 mg/kg) lowered striatal 6-hydroxydopamine levels to 21.6% of control (non-reserpine-treated) values at 1 h, and to 8.9% of control values at 4 h. Levels of 6-hydroxydopamine in the striatum at 1 h were increased 113% by pargyline (100 mg/kg), 145% by alpha-methyldopahydrazine (carbidopa; 25 mg/kg), and 261% by pargyline and carbidopa together. Levels of dopamine in the striatum were unchanged at 2.5 h after 200 mg 6-OH-DOPA/kg (with pargyline and 50 mg carbidopa/kg), whereas levels of norepinephrine in the frontal cortex fell by 77%. At the same time, 6-hydroxydopamine levels were 8.8-fold higher in the striatum (5.54 micrograms/g) than in the cortex (0.63 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
13.
Pascal Genschik Andrée Durr Jacqueline Fleck 《Molecular genetics and genomics : MGG》1994,244(5):548-556
We characterized three genes encoding different E2-type ubiquitin carrier proteins involved in the ubiquitin-mediated proteolytic pathway:UbcAt3 shows homologies to the yeastCDC34 gene andUbcAt4a andUbcAt4b are two different genes homologous to theUbc1/4/5 subfamily in yeast. Their accumulation was analysed and compared with that of the different families encoding polyubiquitins, as well as the monoubiquitin fusion protein, which is considered as a marker for cell division, during various developmental stages including GO/S transition and senescence of higher plant cells. Our results imply that theseUbc genes are under the control of complex mechanisms, and are differentially regulated, but not necessarily co-regulated with ubiquitin genes. Even the closely relatedUbcAt4a andUbcAt4b genes of the same multigene subfamily are controlled by distinct regulatory mechanisms. 相似文献
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Rémy Kachadourian Alia Dellagi Jacqueline Laurent Laurent Bricard Gerhard Kunesch Dominique Expert 《Biometals》1996,9(2):143-150
Iron deprivation of Erwinia amylovora CFBP1430, a species causing fire blight on Pomoïdeae, was shown to induce the production of siderophores of the desferrioxamine (dfo) family and two outer membrane polypeptides with apparent molecular weight of about 70 and 80 kDa, respectively. Cyclic dfo E was characterized as the major metabolite. Phage MudIIpR13 insertional mutagenesis and screening on CAS-agar medium yielded three dfo non-producing and one overproducing clones. These clones failed to grow in the presence of the Fe(III) chelator EDDHA and were determined further as dfo and ferrioxamine transport negative mutants, respectively. The transport mutant which appeared to lack the 70 kDa polypeptide in the outer membrane allowed the purification of dfo E. Growth under iron limitation of dfo negative mutants was stimulated with ferrioxamine E and B but not with other ferrisiderophores tested. The host DNA sequence flanking the left terminal part of the MudIIpR13 prophage responsible for the transport mutation was cloned and used to probe a parental gene library by DNA-DNA hybridization. Two recombinant cosmids restoring the transport mutation to normal were identified. Both cosmids also conferred the ability to utilize ferrioxamine B and E as iron sources on a FhuE1 mutant of Escherichia coli. This correlated with the production of an additional polypeptide of 70 kDa in the outer membrane of E. coli transconjugants, thus confirming that this protein serves the ferrioxamine receptor function (FoxR) in E. amylovora.R. Kachadourian and A. Dellagi have contributed equally to this work. 相似文献
16.
Jacqueline S. Knight Francisco Madueño Simon A. Barnes John C. Gray 《Molecular biotechnology》1996,6(3):335-345
The levels of individual photosynthetic proteins can be independently decreased by theAgrobacterium-mediated transformation of plants with antisens RNA constructs. Protocols for the introduction of such constructs intoAgrobacterium, theAgrobacterium-mediated transformation of tobacco leaf disks, and the screening and analysis of the transgenic plants produced are described. 相似文献
17.
Cloning of the mgtE Mg2+ transporter from Providencia stuartii and the distribution of mgtE in gram-negative and gram-positive bacteria. 总被引:1,自引:1,他引:0 下载免费PDF全文
D E Townsend A J Esenwine J George rd D Bross M E Maguire R L Smith 《Journal of bacteriology》1995,177(18):5350-5354
The MM281 strain of Salmonella typhimurium possesses mutations in each of its three Mg2+ transport systems, requires 100 mM Mg2+ for growth, and was used to screen a genomic library from the gram-negative bacterium Providencia stuartii for clones that could restore the ability to grow without Mg2+ supplementation. The clones obtained also conferred sensitivity to Co2+, a phenotype similar to that seen with the S. typhimurium corA Mg2+ transport gene. The sequence of the cloned P. stuartii DNA revealed the presence of a single open reading frame, which was shown to express a protein with a gel molecular mass of 37 kDa in agreement with the deduced size of 34 kDa. Despite a phenotype similar to that of corA and the close phylogenetic relationship between P. stuartii and S. typhimurium, this new putative Mg2+ transporter lacks similarity to the CorA Mg2+ transporter and is instead homologous to MgtE, a newly discovered Mg2+ transport protein from the gram-positive bacterium Bacillus firmus OF4. The distribution of mgtE in bacteria was studied by Southern blot hybridization to PCR amplification products. In contrast to the ubiquity of the corA gene, which encodes the dominant constitutive Mg2+ influx system of bacteria, mgtE has a much more limited phylogenetic distribution. 相似文献
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What's new in lysozyme research? 总被引:49,自引:0,他引:49
The present review is focused on the main achievements realized in the lysozyme research field since the meeting held in 1972 to commemorate the fiftieth anniversary of the discovery of this enzyme. Despite of extensive structural, physico-chemical, crystallographic, genetic, immunological and evolutionary studies devoted to lysozymes, their biological role is still not exactly known. 相似文献
20.
David E. Moody Jacqueline L. James Edward A. Smuckler 《Biochemical and biophysical research communications》1980,97(2):673-679
Treatment of male rats with carbon tetrachloride, bromotrichloromethane, chloroform, 1,2-dibromoethane, 1-bromo-2-chloroethane, and 1,2-dibromo-3-chloropropane results in a decrease in cytochrome P-450 content and alterations in the relative content of fatty acids in hepatic microsomes. A high correlation was found between the loss of cytochrome P-450, the decrease in arachidonic acid (r=0.93), and the increases in linoleic (r=?0.91) and oleic acids (r=?0.89). 相似文献