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41.
Bacterial flagellar diversity and significance in pathogenesis 总被引:4,自引:0,他引:4
Bacterial flagella are structurally diverse, ranging from the thoroughly investigated model examples found in Escherichia coli and Salmonella typhimurium to the more exotic sheathed flagella of, for example, Helicobacter pylori, and the complex multi-flagellin endoflagella found in many spirochaetes. We summarize some of the emerging structural and genetic findings relating to these more novel flagellar types, and outline their possible significance in the pathogenicity of some medically important bacteria. 相似文献
42.
Interactions between the roach,Rutilus rutilus,and waterfowl populations of Lough Neagh,Northern Ireland 总被引:2,自引:0,他引:2
Ian J. Winfield Denise K. Winfield Catherine M. Tobin 《Environmental Biology of Fishes》1992,33(1-2):207-214
Synopsis Following the introduction of roach, Rutilus rutilus, to a large eutrophic lake in ca. 1973, a subsequent increase in the abundance of this cyprinid through the 1970s was accompanied by a decline in the numbers of one of the lake&s most abundant overwintering waterfowl, the tufted duck, Aythya fuligula, and an increase in overwintering piscivorous great crested grebes, Podiceps cristatus. We suggest that these contrasting trends are causally related and that competition for benthos and increased prey availability are the mechanisms responsible for the changes in the tufted duck and grebe populations respectively. In agreement with these hypotheses, a reduction in the roach population during the mid 1980s was accompanied by a recovery of tufted ducks and a decline of grebes. 相似文献
43.
Ethanol intake and synaptosomal 3H-serotonin uptake were studied in male Fawn-Hooded and Sprague-Dawley rats. Fawn-Hooded rats consumed more alcohol and more water than Sprague-Dawley rats. Plasma alcohol levels of Sprague-Dawley rats were not detectable but were about 5 mg/dl in Fawn-Hooded rats. Ethanol intake increased the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex, but not in thalamus. In Fawn-Hooded rats, serotonin uptake (Vmax) was higher than in Sprague-Dawley rats cortex. Ethanol intake reduced the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex. In cortex, the carrier affinity for serotonin was increased in alcoholized Fawn-Hooded rats. These results indicate that synaptosomal 3H-serotonin uptake is affected by ethanol intake. In Fawn-Hooded rats, high ethanol consumption is associated with high serotonin uptake. In rats presenting high serotonin uptake, alcoholisation reduces 3H-serotonin internalisation in synaptosomes, indicating a specific sensitivity to alcohol intake of serotonin uptake system. 相似文献
44.
α-Amylase activity (EC 3.2. 1.1) is greatly increased in leaves of tobacco (Nicotiana tabacum L. cv Samsun NN) infected with tobacco mosaic virus (TMV). The kinetics of enzyme induction during the hypersensitive reaction resemble those of other hydrolases known to be pathogenesis-related proteins of tobacco. Two α-amylases were purified from TMV-infected leaves and shown to have features in common with well-characterized pathogenesis-related proteins: they are acidic monomers that can be separated upon electrophoresis on basic native gels, and they are found in the apoplastic compartment of the cell. This extra-cellular localization was demonstrated by comparing the α-amylase partition between the intercellular wash fluid and the cell extract with that of proteins of known cellular compartmentalization. These data indicate an active secretion of both α-amylases produced in tobacco upon TMV infection. 相似文献
45.
A gibberellin-regulated gene from wheat with sequence homology to cathepsin B of mammalian cells 总被引:5,自引:0,他引:5
Francisco J. Cejudo George Murphy Catherine Chinoy David C. Baulcombe 《The Plant journal : for cell and molecular biology》1992,2(6):937-948
A previous report described several cDNAs corresponding to mRNAs which accumulated in wheat aleurone layers treated with gibberellic acid (GA) (Baulcombe and Buffard, 1983). The protein sequence deduced from one of these clones (2529) has extensive similarity to the thiol protease, cathepsin B from mammalian cells. Southern analysis of wheat DNA has shown that the 2529 mRNA is encoded by a small family of genes carried on the group 4 chromosome. The nucleotide sequence of a member of the gene family expressed at a low level in aleurone layers and the use of a primer extension assay to identify a clone of a member of the gene family producing an abundant mRNA are reported. The 2529 mRNA accumulates in the scutellum and the aleurone layer of germinating grains where its expression is regulated by GA. In the scutellum the expression was restricted to the parenchyma, suggesting that the 2529 product may have a role other than for mobilization of the endosperm. 相似文献
46.
Anne M. Gallagher Catherine T. Kelly William M. Fogarty 《Applied microbiology and biotechnology》1991,35(4):455-460
Summary The ascosporogenous yeast Lipomyces tetrasporus produced an unusual extracellular carbohydrase. It was purified to homogeneity using ammonium sulphate precipitation and DEAE Bio-gel A ion-exchange chromatography. While retaining highest activity on low-molecular-weight saccharides such as maltose and nigerose, it displays considerable activity towards polymeric substrates including soluble starch. It is particularly unusual in that it also hydrolyses dextran and has a very high affinity for this substrate. The enzyme has an exo-lytic mode of action with the only hydrolysis product, glucose, being released in the -anomeric form. Optimum activity occurs at pH 4.5 and at 50°C. It is a glycoprotein, and has an M
r value of 150 000 (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) — 183 000 (fast protein liquid chromatography) and a pI of 6.0.
Offprint requests to: C. T. Kelly 相似文献
47.
Twila Jackson Michael F. Allard Catherine M. Sreenan Lisa K. Doss Sanford P. Bishop Judith L. Swain 《Molecular and cellular biochemistry》1991,104(1-2):15-19
Transgenic animals provide a model system to elucidate the role of specific proteins in development. This model is now being used increasingly in the cardiovascular system to study cardiac growth and differentiation. During cardiac myocyte development a transition occurs from hyperplastic to hypertrophic growth. In the heart the switch from myocyte proliferation to terminal differentiation is synchronous with a decrease in c-myc mRNA abundance. To determine whether c-myc functions to regulate myocyte proliferation and/or differentiation, we examined the in vivo effect of increasing c-myc expression during fetal development and of preventing the decrease in c-myc mRNA expression that normally occurs during myocyte development. The model system used was a strain of transgenic mice exhibiting constitutive expression of c-myc mRNA in cardiac myocytes throughout development. Increased c-myc mRNA expression is associated with both atrial and ventricular enlargement in the transgenic mice. This increase in cardiac mass is secondary to myocyte hyperplasia, with the transgenic hearts containing greater than twice as many myocytes as nontransgenic hearts. The results of this study indicate that constitutive expression of c-myc mRNA in the heart during development results in enhanced hyperplastic growth, and suggest a regulatory role for the c-myc protooncogene in cardiac myogenesis. 相似文献
48.
Tom Lanaras Catherine M. Cook Ann P. Wood Don P. Kelly Geoffrey A. Codd 《Archives of microbiology》1991,156(5):338-343
The bacterial symbionts of many marine invertebrates contain ribulose 1,5-bisphosphate (RuBP) carboxylase but apparently no carboxysomes, polyhedral bodies containing RuBP carboxylase. In the few cases where polyhedral bodies have been observed they have not been characterised enzymatically. Polyhedral bodies, 50–90 nm in diameter, were observed in thin cell sections of Thiobacillus thyasiris the putative symbiont of Thyasira flexuosa and RuBP carboxylase activity was detected in both soluble and particulate fractions after centrifugation of cell-free extracts. RuBP carboxylase purified 90-fold from the soluble fraction was of high molecular weight and consisted of large and small subunits, with molecular weights of 53,110 and 11,100 respectively. Particulate RuBP carboxylase activity was associated with polyhedral bodies 50–100 nm in diameter, as revealed by density gradient centrifugation and electron microscopy. Therefore, the polyhedral bodies were inferred to be carboxysomes. Native electrophoresis of isolated carboxysomes demonstrated a major band which comigrated with the purified RuBP carboxylase and three minor bands of lower molecular weight. Sodium dodecyl-sulphate (SDS) gel electrophoresis of SDS-dissociated carboxysomes demonstrated nine major polypeptides two of which were the large and small subunits of RuBP carboxylase. The RuBP carboxylase subunits represented 21% of the total carboxysomal protein. The most abundant polypeptide had a molecular weight of 40,500. Knowledge of carboxysome composition is necessary to provide an understanding of carboxysome function.Abbreviations FPLC
fast performance liquid chromatography
- IB
isolation buffer
- PAGE
polyacrylamide gel electrophoresis
- RuBP
carboxylase
- ribulose
1,5-bisphosphate carboxylase/oxygenase
- SDS
sodium dodecyl-sulphate 相似文献
49.
Monique Berthelon Catherine Caillaud Françoise Rey Philippe Labrune Dominique Melle Josué Feingold Jean Frézal Marie-Louise Briard Jean-Pierre Farriaux Pierre Guibaud Hubert Journel Bernard Le Marec Nicole Maurin Jean-Louis Nivelon Henri Plauchu Jean-Marie Saudubray Philippe Tron Jean Rey Arnold Münnich Stanislas Lyonnet 《Human genetics》1991,86(4):355-358
Summary A total of 252 chromosomes from 126 patients with phenylalanine hydroxylase (PAH) deficiencies were analyzed for both mutant genotypes and restriction fragment length polymorphism (RFLP) haplotypes at the PAH locus. The mutant genes studied originated either from Western Europe (116 alleles) or from Mediterranean countries (136 alleles). Only 27% of all mutant alleles were found to carry identified mutations, particularly mutations at codon 252 (2.3%), 261 (7.5%), 280 (6.3%), 408 (3.5%) and at the splice donor site of intron 12 (6.3%). The mutant genotypes were associated with RFLP haplotypes 7, 1, 38, 2 and 3 at the PAH locus respectively. Except for the splice mutation of intron 12, these associations were preferential, but not exclusive, since the other four mutations were found on the background of at least two RFLP haplotypes. These results, together with the observation that 85% of PAH deficient patients are heterozygotes for their mutant genotypes, emphasize the great heterogeneity of PAH deficiencies in Mediterranean countries and hamper systematic DNA testing for carrier status in this population. 相似文献
50.
Clinical and molecular heterogeneity of phenylalanine hydroxylase deficiencies in France 总被引:20,自引:10,他引:10
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Franoise Rey Monique Berthelon Catherine Caillaud Stanislas Lyonnet Vronique Abadie Flicienne Blandin-Savoja Josu Feingold Jean-Marie Saudubray Jean Frzal Arnold Munnich Jean Rey 《American journal of human genetics》1988,43(6):914-921
RFLPs of 68 normal and 74 mutant alleles at the phenylalanine hydroxylase (PAH) locus were determined in 37 French kindreds. A total of 23 haplotypes, including 18 normal and 16 mutant alleles, were observed. Two-thirds of all mutant alleles were confined within only four haplotypes, while the last third was accounted for by 12 haplotypes, including eight haplotypes absent from Caucasian pedigrees reported thus far. Several mutant haplotypes were present in typical phenylketonuria only, others were present in variants only, and some were present in both. In addition, a particular mutant haplotype (haplotype 2) was found to harbor different mutations in our series, resulting in either typical phenylketonuria or in mild hyperphenylalaninemias. The diploid combination of so many mutant haplotypes in PAH-deficient patients and of compound heterozygosity at the PAH locus in southern Europe might account for the broad spectrum of individual phenotypes observed in France. 相似文献