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1.
Effects of adenosine deaminase on the sensitivity of glucose transport, glycolysis and glycogen synthesis to insulin in muscles of the rat 总被引:4,自引:0,他引:4
B Leighton F J Lozeman I G Vlachonikolis R A Challiss J A Pitcher E A Newsholme 《The International journal of biochemistry》1988,20(1):23-27
1. Soleus, extensor digitorum longus (EDL) or hemi-diaphragm muscles of the rat were incubated in the presence of insulin and rates of the processes of glycolysis and glycogen synthesis were measured. 2. The concentrations of insulin required to cause half-maximal stimulation of glycolysis in both soleus and EDL preparations were significantly decreased by the presence of adenosine deaminase in the medium. 3. Adenosine deaminase increased the sensitivity of the process of hexose transport to insulin (in an identical manner to the change in sensitivity of glycolysis) in the EDL preparation. 4. None of the adenosine mediated effects on insulin-stimulated rates of glycolysis were observed in the hemi-diaphragm preparation or on the rates of glycogen synthesis in any of the three muscle preparations. 5. Therefore, changes in the adenosine system in skeletal muscle influence insulin sensitivity regardless of fibre type composition of the muscle. 相似文献
2.
WhileEscherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains ofE. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. EnterotoxigenicE. coli (ETEC) is the most extensively studied of the five categories ofE. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenicE. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three, additional categories ofE. coli diarrheal disease, their colonization factors and their host cell receptors are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and thatE. coli is part of these biofilms as both commensals and pathogens.Abbreviations CF
colonization factor
- CFA
Colonization Factor Antigen
- CS
coli-surface-associated antigen
- EAggEC
enteroaggregativeE. coli
- ECDD
E. coli diarrheal disease
- EHEC
enterohemorrhagicE. coli
- EIEC
enteroinvasiveE. coli
- EPEC
enteropathogenicE. coli
- ETEC
enterotoxigenicE. coli
- Gal
galactose
- GalNAc
N-acetyl galactosamine
- LT
heat-labile toxin
- NeuAc
N-acetyl neuraminic acid
- PCF
Putative colonization factor
- RBC
red blood cells
- SLT
Shiga-like toxin
- ST
heat-stable toxin 相似文献
3.
DNA sequences were determined for three to five alleles of the bride-of-
sevenless (boss) gene in each of four species of Drosophila. The product of
boss is a transmembrane receptor for a ligand coded by the sevenless gene
that triggers differentiation of the R7 photoreceptor cell in the compound
eye. Population parameters affecting the rate and pattern of molecular
evolution of boss were estimated from the multinomial configurations of
nucleotide polymorphisms of synonymous codons. The time of divergence
between D. melanogaster and D. simulans was estimated as approximately 1
Myr, that between D. teissieri and D. yakuba as approximately 0.75 Myr, and
that between the two pairs of sibling species as approximately 2 Myr. (The
boss genes themselves have estimated divergence times approximately 50%
greater than the species divergence times.) The effective size of the
species was estimated as approximately 5 x 10(6), and the average mutation
rate was estimated as 1-2 x 10(-9)/nucleotide/generation. The ratio of
amino acid polymorphisms within species to fixed differences between
species suggests that approximately 25% of all possible single-step amino
acid replacements in the boss gene product may be selectively neutral or
nearly neutral. The data also imply that random genetic drift has been
responsible for virtually all of the observed differences in the portion of
the boss gene analyzed among the four species.
相似文献
4.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
5.
Oligomeric forms of the membrane-bound acetylcholine receptor disclosed upon extraction of the M(r) 43,000 nonreceptor peptide 下载免费PDF全文
FJ Barrantes 《The Journal of cell biology》1982,92(1):60-68
Oligomeric forms of the acetylcholine receptor are directly visualized by electron microscopy in receptor-rich membranes from torpedo marmorata. The receptor structures are quantitatively correlated with the molecular species so far identified only after detergent solubilization, and further related to the polypeptide composition of the membranes and changes thereof. The structural identification is made possibly by the increased fragility of the membranes after extraction of nonreceptor peptides and their subsequent disruption upon drying onto hydrophilic carbon supports. Receptor particles in native membranes depleted of nonreceptor peptides appear as single units of 7-8 nm, and double and multiple aggregates thereof. Particle doublets having a main-axis diameter of 19 +/- 3 nm predominate in these membranes. Linear aggregates of particles similar to those observed in rotary replicas of quick-frozen fresh electrolytes (Heuser, J.E. and S. R. Salpeter. 1979, J. Cell Biol. 82: 150-173) are also present in the alkaline-extracted membranes. Chemical modifications of the thiol groups shift the distribution of structural species. Dithiothreitol reduction, which renders almost exclusively the 9S, monomeric receptor form, results in the observation of the 7-8 nm particle in isolated form. The proportion of doublets increases in membranes alkylated with N-ethylmaleimide. Treatment with 5,5’-dithiobis-(nitrobenzoic acid) increases the proportion of higher oligomeric species, and particle aggregates (n=oligo) predominate. The nonreceptor v-peptide (doublet of M(r) 43,000) appears to play a role in the receptor monomer-polymer equilibria. Receptor protein and v-peptide co-aggregate upon reduction and reoxidation of native membranes. In membranes protected ab initio with N- ethylmaleimide, only the receptor appears to self-aggregate. The v-peptide cannot be extracted from these alkylated membranes, though it is easily released from normal, subsequently alkylated or reduced membranes. A stabilization of the dimeric species by the nonreceptor v-peptide is suggested by these experiments. Monospecific antibodies against the v-peptide are used in conjunction with rhodamine- labeled anti-bodies in an indirect immunoflourescence assay to map the vectorial exposure of the v-peptide. When intact membranes, v-peptide depleted and “holey” native membranes (treated with 0.3 percent saponin) are compared, maximal labeling is obtained with the latter type of membranes, suggesting a predominantly cytoplasmic exposure of the antigenic determinants of the v-peptide in the membrane. The influence of the v-peptide in the thiol-dependent interconversions of the receptor protein and the putative topography of the peptide are analyzed in the light of the present results. 相似文献
6.
D W Litchfield B Lüscher F J Lozeman R N Eisenman E G Krebs 《The Journal of biological chemistry》1992,267(20):13943-13951
In human epidermal carcinoma A431 cells, the beta subunit of casein kinase II is phosphorylated at an autophosphorylation site and at serine 209 which can be phosphorylated in vitro by p34cdc2 (Litchfield, D. W., Lozeman, F. J., Cicirelli, M. F., Harrylock, M., Ericsson, L. H., Piening, C. J., and Krebs, E. G. (1991) J. Biol. Chem. 266, 20380-20389). Given the importance of p34cdc2 in the regulation of cell cycle events, we were interested in examining the phosphorylation of casein kinase II during different stages of the cell cycle. In this study it is demonstrated that the extent of phosphorylation of serine 209 in the beta subunit is significantly increased relative to phosphorylation of the autophosphorylation site when chicken bursal lymphoma BK3A cells are arrested at mitosis by nocodazole treatment. This result suggests that serine 209 is a likely physiological target for p34cdc2. In addition, the alpha subunit of casein kinase II also undergoes dramatic phosphorylation with an associated alteration in its electrophoretic mobility when BK3A cells or human Jurkat cells are arrested with nocodazole. Phosphopeptide mapping studies indicate that p34cdc2 can phosphorylate in vitro the same peptides on the alpha subunit that are phosphorylated in cells arrested at mitosis. These phosphorylation sites were localized to serine and threonine residues in the carboxyl-terminal domain of alpha. Taken together, the results of this study indicate that casein kinase II is a probable physiological substrate for p34cdc2 and suggest that its functional properties could be affected in a cell cycle-dependent manner. 相似文献
7.
Huff PW Lozeman FJ Kazala EC Prozniak C Wegner J Deng J Laroche A Mir PS Aalhus J Weselake RJ 《Analytical biochemistry》2003,318(2):254-259
Meaningful estimates of diacylglycerol acyltransferase (EC 2.3.1.20) activity in different tissue samples require effective, unbiased methods of sample storage. Samples of the pars costalis diaphragmatis muscle (skirt muscle of the diaphragm) were obtained from 18- to 20-month-old cattle and assayed for microsomal protein content and diacylglycerol acyltransferase activity after having been stored under various conditions as dissected tissue or microsomes prepared from dissected tissue. There was relative enrichment of diacylglycerol acyltransferase specific activity (p<0.05) when samples prepared from the pars costalis diaphragmatis muscle were dehydrated and stored for 2 weeks, as compared to the control condition (in which the microsome fraction was prepared from fresh pars costalis diaphragmatis muscle and assayed immediately). The results suggested that dehydration was an effective method of storage for bovine muscle samples destined for estimation of the microsomal diacylglycerol acyltransferase activity. The dehydration approach for preparing samples for analysis of diacylglycerol acyltransferase activity might also prove useful to investigators who are interested in obtaining reliable estimates of the activity of other enzymes in tissue samples. 相似文献
8.
Peggy CR Godschalk Mathijs P Bergman Raymond FJ Gorkink Guus Simons Nicole van den Braak Albert J Lastovica Hubert P Endtz Henri A Verbrugh Alex van Belkum 《BMC microbiology》2006,6(1):32-13
Background
Campylobacter jejuni is the predominant cause of antecedent infection in post-infectious neuropathies such as the Guillain-Barré (GBS) and Miller Fisher syndromes (MFS). GBS and MFS are probably induced by molecular mimicry between human gangliosides and bacterial lipo-oligosaccharides (LOS). This study describes a new C. jejuni-specific high-throughput AFLP (htAFLP) approach for detection and identification of DNA polymorphism, in general, and of putative GBS/MFS-markers, in particular. 相似文献9.
10.
Sylvanne M Daniels Carlos E Melendez-Peña Robert J Scarborough Aïcha Daher Helen S Christensen Mohamed El Far Damian FJ Purcell Sébastien Lainé Anne Gatignol 《BMC molecular biology》2009,10(1):38-13