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1.
The role of minor components of the leaves ofZostera marina L. in altering the activity of micro-organisms directly and indirectly by affecting amphipod grazers was investigated in laboratory experiments. Water-soluble extracts of eelgrass leaves inhibited the growth of many marine bacteria and a micro-alga (Platymonas sp.) at concentrations equivalent to as little as 10 g dry wt. of leaf.ml–1. The potency of leaf extracts was higher in young, actively metabolizing tissue than in older leaves, and was higher in leaves collected in summer during rapid growth than in winter. Water-soluble inhibitors may explain the low biomass of epiphytes on actively growing leaves. Phenolic acids, previously identified in eelgrass leaves, may account for part of the antimicrobial activity. Three free phenolic acids inhibited the test micro-organisms at concentrations as low as 2 M; caffeic acid was more potent than either protocatechuic or gentisic acid. Extracts of young leaves also inhibited grazing by amphipods on dead leaves. The time required for leaching of soluble inhibitors may account for the delay observed between the loss of leaves from the plants and the onset of grazing. Thus, interactions among the biotic components of the detritus ecosystem may be significantly modified by minor components of the macrophyte tissue.  相似文献   

2.
Efferent and reciprocal synapses have been demonstrated in the carotid body of the domestic fowl (Gallus gallus domesticus). Synapses were also found with purely afferent morphology, but were probably components of reciprocal synapses. The general morphology of the endings suggested the presence of two types of axon, afferent axons making reciprocal and perhaps afferent synapses with Type I cells, and efferent axons making efferent synapses with Type I cells. A few axo-dendritic synapses were also found. The dense-cored vesicles associated with the afferent components of reciprocal synapses and with the possible true afferent synapses varied in diameter and core but could belong to one population of pre-synaptic vesicles. These observations are consistent wtih a new theory for the carotid body receptor mechanism. This proposes a spontaneously discharging afferent axon inhibited by an inhibitory transmitter substance released by the Type I cell via the "afferent" component of its reciprocal synapse, the "efferent" component inhibiting this release. Besides this chemoreceptor modulation of its afferent axon, the Type I cell may also have a general secretory function.  相似文献   

3.
Red wine and its components have been shown to possess cardioprotective and anti-atherogenic effects. Additionally, red wine and many of its components like catechin, epicatechin, rutin, transresveratrol and quercetin possess antioxidant properties. Oxidized low density lipoprotein (LDL) is involved in the development of an atherosclerotic lesion. Red wine, therefore, may be anti-atherogenic because of its antioxidant effects on LDL modification. This study examined the antioxidant effects of catechin, epicatechin, rutin, transresveratrol, quercetin and Merlot wines on LDL oxidation. Merlot was chosen because although other red wines have been tested, limited information exists for this variety. Oxidation was carried out with AAPH (2,2-Azo-bis(2-amidinopropane) dihydrochloride) and AMVN (2,2-Azo-bis(2,4-dimethylvaleronitrile)), as water and lipid soluble peroxyl radical generating systems (FRGS), respectively. This allowed us to determine the lipophilic antioxidant characteristics of the wine and its components. Conjugated diene assays were used to measure LDL oxidation over 6 hrs. In an AAPH system, all polyphenolic compounds except transresveratrol displayed an antioxidant effect. LDL oxidation by AAPH was also inhibited by aliquots of Merlot wine. No antioxidant effects were observed in an AMVN environment except for a mild antioxidant effect by quercetin. Surprisingly, incubation of LDL with Merlot wine strongly protected against oxidation by AMVN. In summary, the five phenolic compounds displayed antioxidant effects in a water soluble free radical generating system, but only quercetin showed this in a lipid soluble one. However, red wine inhibited LDL oxidation by both water and lipid soluble free radical generating systems. Our data suggest, therefore, that red wines contain unidentified antioxidants that provide protection against LDL oxidation within a lipid soluble environment. (Mol Cell Biochem 263: 211–215, 2004)  相似文献   

4.
5.
Summary Some plant lectins, Concanavalin agglutinin (Con A), succinyl Con A and wheat germ agglutinin (WGA) increased the adhesion of dissociated embryonic cells of the sea urchin,Pseudocentrotus depressus, to the substratum (plastic and glass surface) in vitro. Other plant lectins,Ulex europeus agglutinin (UEA) andDolichos biflorus agglutinin (DBA) had no effect on the cell-to-substratum interaction. A specific monocarbohydrate inhibitor of lectins, -methyl-d-mannoside, inhibited the Con A-induced cell-to-substratum adhesion of dissociated embryonic cells. This observation suggests that the Con A-induced cell-to-substratum adhesion may be attributed to the Con A-carbohydrate interaction. In Millipore-filtered sea water (MPFSW) containing Con A (0.1 mg/ml), dissociated embryonic cells adhered to the substratum for more than 6 h at 18°C, while in MPFSW as control, almost all the dissociated cells were released from the substratum after 1 h. A scanning electron microscopic study showed that dissociated embryonic cells adhered to the substratum were surrounded by an extracellular fibrous material, when the cells were cultured in MPFSW containing Con A. The induction of the extracellular fibrous material by Con A was inhibited by -methyl-d-mannoside. The appearance of this material may be related to the cell-to-substratum adhesion of dissociated cells. Sequential extractions of Con A-treated dissociated cells with Triton X 100 and urea solubilized most of the cellular components, leaving the fibrous material on the surface. Biochemical conponents of the isolated fibrous material included sea urchin fibronectin, Con A and minor components (88 and 140 kilodalton proteins). Fibronectin preformed in the cells was excreted after the dissociation, while the 88 and 140 kilodalton proteins were synthesized and released to the extracellular space.  相似文献   

6.
Exopolysaccharide (EPS) is produced by many marine bacteria and is important for cell aggregation in the ocean. d-amino acids are important components in bacteria and are recently recognized as signal molecules for regulation of bacterial growth. In this study, the effects of d-amino acids on EPS production, cell aggregation, and metabolic activity were investigated using an EPS-producing bacterium Alteromonas macleodii strain JL2069. EPS produced by JL2069 was inhibited by 1 mM of d-Ala and d-Ser, but not by d-Glu. The formation of particulate organic matter (POM) was promoted by the three amino acids. A new technique of microcalorimetry analysis indicated that the metabolic activity of the JL2069 cells was inhibited by these d-amino acids. Our results suggested that d-amino acids may reduce the bacterial metabolism by changing bacterial lifestyle from planktonic to cell aggregation growth which occurs independent of the production of EPS.  相似文献   

7.
On a preparation of isolated spinal cord of the frog Rana ridibunda, using intracellular recording from lumbar motoneurons, there were compared effects of GABA and Gly on membrane potentials, membrane resistance, and EPSP evoked by activation of dorsal root fibers or of brainstem reticular formation. All parameters were compared in the same cell. At the same concentration (10 mM), Gly evoked membrane depolarization by 20–50% greater than GABA. Response of application of a mixture of GABA and Gly was by 20% lower than the arithmetic sum of responses to the GABA application and the Gly application. The late components and the semiwidth both of complex and of simpler DR and RF EPSP decreased significantly (to 95%) on the background of application of GABA and Gly. The late components of the both EPSP were inhibited stronger by GABA than by Gly. The early mono- and disynaptic EPSP components were inhibited to the essentially lesser degree than the late components. Gly always inhibited the early DR EPSP more markedly than GABA did. In the greater part of motoneurons the early RF EPSP were stronger inhibited by Gly, in their smaller part, by GABA. In many motoneurons the early components did not decrease at all. The motoneuron membrane resistance decreased under effect of GABA and Gly to the approximately equal extent (by 10–30%). Not in all neurons there was revealed the correspondence between a decrease of the membrane resistance (RM) and a decrease of the early EPSP components. Based on the obtained data, it is suggested that the inhibitory influences in frogs is mediated by both Gly- and GABA-receptors. On the membrane of motoneuron the inhibition is mediated to the relatively greater degree by Gly-receptors, whereas on the membrane of interneurons, by GABA-receptors. During inhibition of DR EPSP the predominance of Gly-receptors is observed in the greater number of motoneurons than during inhibition of RF EPSP. Between individual motoneurons there are significant quantitative differences of all parameters.  相似文献   

8.
Active movements of the chromosomes may be needed in the process, where homologous chromosomes find each other during the meiotic pairing. Because the components of the cytoskeleton are generally believed to be responsible for all movements in living nonmuscle cells, we have analyzed the regulation of the movements of zygotene chromosomes in the male rat by using specific inhibitors of the assembly of the various components of the cytoskeleton. — Colcemid, an inhibitor of microtubule formation, completely inhibited the chromosome movements in vitro at a concentration of 1 g/ml. This was associated with a damage of the nuclear envelope revealed by the electron microscopic analysis. Another inhibitor of microtubule formation, vinblastine, was ineffective below the level of general toxicity (100 g/ml). A specific microfilament inhibitor, cytochalasin B was similarly ineffective. — The findings suggest the presence of a specific colcemid-sensitive mechanism in the nuclear envelope of the zygotene spermatocytes, which regulates the movements of the chromosomes during meiotic pairing.  相似文献   

9.
The molecular components of a phenolic fraction (P2), obtained from liquid chromatography of a Swiss Chard (Beta vulgaris subsp. cycla) extract, were identified using HPLC-ESI-MS/MS. The primary P2 components were: vitexin-2'O-rhamnoside, its demethylated form 2'-xylosylvitexin, isorhamnetin 3-gentiobioside, and rutin. P2 "in toto" and the single components were characterized for antioxidant capacity, antimitotic activity on MCF-7 human breast cancer cells and for toxicity to human lymphocytes and macrophages. P2 inhibited MCF-7 cell proliferation (IC(50) value = 9 microg/ml) without inducing apoptosis, showed no toxicity to human lymphocytes and slight toxicity to macrophages. Vitexin-2'O-rhamnoside strongly inhibited DNA synthesis in MCF-7 cells, whereas 2'-xylosylvitexin and isorhamnetin 3-gentiobioside were activators; combinations of activators and inhibitors maintained the over-all inhibitory effect.  相似文献   

10.
POLYARTHRITIS induced in rats by the administration of complete Freund's adjuvant is an immunologically mediated disease which can be passively transferred with cells1. Using this model, we have recently described2 the development of a non-complement-dependent antibody specific for lipoprotein antigenic components of Mycobacterium butyricum (Mb). The antibody response precedes both the development of the disease and purified protein derivative (PPD) skin reactivity and is not inhibited by effective doses of immunosuppressive agents that prevent disease and modify PPD reactivity. These observations suggested that the Mb antibody may have a regulatory function in the disease process.  相似文献   

11.
Two operation regimes of the electron transport system were found in rat liver mitochondria during the cyanide-resistant succinate oxidation catalyzed by menadione. Under isotonic conditions, the mitochondria were found to contain two electron transport components, one of which was sensitive to mucidin, whereas the other one was inhibited by antimycin A. Both electron transport components were inhibited by thenoyltrifluoroacetone (TTFA). In hypotonic media, the polyenzymatic respiratory complex of mitochondria underwent transformations. In this case the electron transport during the cyanide-resistant succinate oxidation was insensitive to mucidin and antimycin A and was suppressed only by TTFA. Some experimental evidence in favour of pathways of electron transfer under different regimes of mitochondrial function was obtained. It was supposed that in isotonic incubation media the cyanide-resistant respiration is mainly due to menadione reduction in two points of the Q-cycle, i.e., in the region of the "i" center and in the "o" center. Under hypotonic conditions, the main electron flux to menadione occurs only via the Q-cycle "i" center. The observed relatively slow reduction of cytochromes b and ci+c plays an insignificant role in the cyanide-resistant respiration. It was shown that the ability of menadione to stimulate the cyanide-resistant respiration is correlated with a higher polarity of this compound as compared with CoQ2 and endogenous CoQ10 of mitochondria. The role of the polyisoprenoid substituent in CoQ10 as a structural component providing for the specificity of interaction with mitochondrial respiratory chain carriers is discussed.  相似文献   

12.
The kinetics and specificity of GABA and taurine uptake were studied in the bullfrog sympathetic ganglia. GABA uptake system consisted of simple saturable component and taurine uptake system consisted of two saturable components exclusive of non-saturable influx. Taurine unaffected GABA uptake while GABA inhibited taurine uptake competitively with theK i/Km ratio of 38. GABA (5.14 M) uptake was inhibited by -aminovaleric acid and slightly by 2,4-diaminobutyric acid (5 mM, each) among ten structural analogs. Taurine uptake under high-affinity conditions was most strongly suppressed by hypotaurine and -alanine competitively with theK i/Km ratio of 1.0 and 1.9, respectively. Autoradiography showed that glial cells were heavily labeled by both [3H]GABA and [3H]taurine. These results suggest that GABA is transported by a highly specific carrier system distinct from the taurine carrier and that taurine, hypotaurine, and -alanine may share the same high-affinity carrier system in the glial cells of the bullfrog sympathetic ganglia.  相似文献   

13.
Two different spectral analyses of heart rate (HR) variability (HRV) were performed on seven young male subjects to evaluate the effects of different color temperatures of light exposure (6700 K, 5000 K, 3000 K) before sleep on cardiac vagal activity. In investigating HRV, we used an ordinary fast Fourier transform (FFT) and coarse graining spectral analysis (CGSA), which selectively extracts random fractal components from a given time series. The results showed that suppressions of HR during sleep after 6700 K light exposure were more inhibited than the other two lighting conditions. Increases in high-frequency (HF) components of HRV during sleep were also inhibited by 6700 K pre-sleep lighting. These results indicate that pre-sleep exposure to light of a higher color temperature may inhibit the enhancement of cardiac vagal activity during sleep. Moreover, significant HF alterations were shown in fractal-free HF (not in ordinary HF) components by CGSA. Because the HF component originates from respiratory sinus arrhythmia with periodical fluctuations, CGSA may be an appropriate approach for HRV evaluation during sleep.  相似文献   

14.
We investigated the properties of an artificial chimeric peptide that contains an Arg-Gly-Asp (RGD)-tripeptide, the versatile cell recognition signal of extracellular matrix protein components, coupled to a carboxyl-terminal fragment of the highly specific alpha-thrombin inhibitor, hirudin (residues 53-64): WGRGDSANGDFEEIPEEYL (RGD-hirudin53-64). Hirudin53-64 and RGD-hirudin53-64 inhibited the fibrinogen clotting activity of alpha-thrombin and prolonged the activated partial thromboplastin time of human plasma. In addition, both peptides afforded total protection to thrombin from trypsionolysis. Neither hirudin53-64 nor RGD-hirudin53-64 dramatically interfered with the thrombin-antithrombin inhibition reaction either in the absence or presence of added heparin. alpha-Thrombin-induced platelet aggregation was effectively inhibited by hirudin53-64 and RGD-hirudin53-64. Unlike hirudin53-64, RGD-hirudin53-64 in solution inhibited integrin-mediated endothelial cell and fibroblast cell attachment to polystyrene wells in the presence of fetal bovine serum. Collectively, our results demonstrate that RGD-hirudin53-64 has anticoagulant/antiplatelet aggregation activity attributable to its hirudin sequence and integrin-directed cell attachment activity due to its RGD site. Our results suggest that this chimeric motif may serve as a prototype for a new class of anticoagulants where an integrin-specific sequence "targets" the peptide to a cell (ultimately through the platelet integrin alpha IIb beta 3) trapped amid a thrombus with ensuing proteinase inhibition.  相似文献   

15.
The kinetics of l-aspartate transport into pea chloroplasts was studied in the presence and absence of transport inhibitors to determine whether multiple aspartate carriers exist. Transport was measured by the silicone oil centrifugation technique. Reciprocal plots of concentration-dependent transport rates were biphasic, indicating the presence of two transport components, distinguishable on the basis of their affinity for aspartate. These transport components, called high affinity and low affinity transport could also be distinguished on the basis of their apparent substrate saturability and their sensitivity to media pH. The apparent Km for high affinity transport was 30 micromolar. The Km for low affinity transport was not determined. To test whether these transport components could also be distinguished on the basis of inhibitor sensitivity and to assess the value of inhibitors for distinguishing multiple aspartate translocators, a survey of several classes of potential inhibitors was conducted. High affinity aspartate transport was inhibited by p-chloromercuribenzenesulfonate and mersalyl, both sulfhydryl-reactive reagents; diethyl pyrocarbonate, a histidine-reactive reagent; and nigericin and carbonyl cyanide m-chlorophenylhydrazone, both ionophores. Low affinity aspartate transport was not inhibited by p-chloromercuribenzenesulfonate or nigericin, but preliminary results suggest it was sensitive to diethyl pyrocarbonate. Because the high and low affinity transport components could be distinguished not only by their sensitivity to media pH and substrate saturability, but also by their sensitivity to various inhibitors, we concluded that they may represent different transport systems or carriers.  相似文献   

16.
Thyrotropin-releasing hormone, TRH, increases the plasma levels of glucagon, insulin, glucose and free fatty acids in rabbits. However, TRH has no direct effects on the release of hormones neither from the endocrine pancreas in humans nor from the isolated perfused rat pancreas. The aim of the present study was to investigate if the effects of TRH in rabbits were mediated by the autonomic nervous system. The TRH "Roche"-induced hyperglucagonemia was inhibited by phentolamine (an alpha-receptor blocking drug), yohimbine (an alpha-2 -receptor blocking drug) and atropine. The TRH "Roche"-induced hyperinsulinemia was inhibited by propranolol (a beta-receptor blocking drug). The TRH "Roche"-induced hyperglycemia was inhibited by all four drugs. The TRH "Roche"-induced increases in the plasma levels of free fatty acids were not inhibited by the sympathetic and parasympathetic blocking drugs. The effects of TRH "Roche" on the plasma levels of glucagon, insulin and glucose cannot be explained by increases in the plasma levels of catecholamines. TRH, given intravenously into rabbits, may possibly act on regions in the central nervous system which control carbohydrate metabolism and the release of glucagon and insulin from the endocrine pancreas by sympathetic and parasympathetic mechanisms.  相似文献   

17.
To analyze components of the idiotypic network in experimental autoimmune disease, we produced 17 isogeneic anti-idiotopic monoclonal antibodies (anti-Id) against two experimental autoimmune myasthenia gravis-producing anti-acetylcholine receptor (anti-AChR) monoclonal antibodies. We studied the binding of five of the anti-Id to the anti-AChR monoclonal antibodies bearing the complementary idiotopes (Id-mAb). They bound with Kd values ranging from 0.06 to 0.86 nM, values comparable to those of Id-mAb:AChR complexes (0.26 and 0.34 nM). All of the anti-Id tested moderately inhibited the binding of AChR to Id-mAb, whereas for each anti-Id, AChR either strongly inhibited anti-Id binding or had no effect on anti-Id binding. Hence, the inhibition of Id-mAb:AChR binding by anti-Id was not reciprocal with the inhibition of anti-Id:Id-mAb binding by AChR. For each anti-Id, the relative affinities of anti-Id and AChR for Id-mAb together with the lack of symmetry of inhibition by anti-Id compared to inhibition by AChR indicate that these two "ligands" are not competitive inhibitors. Consequently, anti-Id and AChR do not bind to overlapping sites on the Id-mAb, suggesting that the observed inhibition is mediated allosterically. This may be a common mechanism of anti-Id:Id binding, which would have important implications for the mechanism of anti-Id-induced suppression.  相似文献   

18.
1. When pig ear skin slices were cultured for 18h in the presence of 1μg of tunicamycin/ml the incorporation of d-[3H]glucosamine into the epidermis, solubilized with 8m-urea/5% (w/v) sodium dodecyl sulphate, was inhibited by 45–55%. This degree of inhibition was not increased by using up to 5μg of tunicamycin/ml or by treating the skin slices with tunicamycin for up to 8 days. The incorporation of (U-14C)-labelled l-amino acids under these conditions was not affected by tunicamycin. Polyacrylamide-gel electrophoresis indicated that the labelling of the major glycosaminoglycan peak with d-[3H]glucosamine was unaffected, whereas that of the faster migrating glycoprotein components was considerably decreased in the presence of tunicamycin. 2. Subcellular fractionation indicated that tunicamycin specifically inhibited the incorporation of d-[3H]glucosamine but not of (U-14C)-labelled l-amino acids into particulate (mainly plasma-membrane) glycoproteins by about 70%. The labelling of soluble glycoproteins was hardly affected. Polyacrylamide-gel electrophoresis of the plasma-membrane fraction showed decreased d-[3H]glucosamine incorporation into all glycoprotein components, indicating that the plasma-membrane glycoproteins contained mainly N-asparagine-linked oligosaccharides. 3. Cellulose acetate electrophoresis of both cellular and extracellular glycosaminoglycans showed that tunicamycin had no significant effect on the synthesis of the major component, hyaluronic acid. However, the incorporation of both d-[3H]glucosamine and 35SO42− into sulphated glycosaminoglycans was inhibited by about 50%. This inhibition was partially overcome, at least in the cellular fraction, by 2mm-p-nitrophenyl β-d-xyloside indicating that tunicamycin-treated epidermis retained the ability to synthesize sulphated glycosaminoglycan chains. Tunicamycin may affect the synthesis and/or degradation of proteoglycan core proteins or the xylosyltransferase. 4. Electron-microscopic examination of epidermis treated with tunicamycin for up to 4 days revealed no significant changes in cell-surface morphology or in epidermal-cell adhesion. Either N-asparagine-linked carbohydrates play little role in epidermal-cell adhesion or more probably there is little turnover of these components in epidermal adhesive structures such as desmosomes and hemidesmosomes during organ culture.  相似文献   

19.
Woo HM  Kang JH  Kawada T  Yoo H  Sung MK  Yu R 《Life sciences》2007,80(10):926-931
Inflammation plays a key role in obesity-related pathologies such as cardiovascular disease, type II diabetes, and several types of cancer. Obesity-induced inflammation entails the enhancement of the recruitment of macrophages into adipose tissue and the release of various proinflammatory proteins from fat tissue. Therefore, the modulation of inflammatory responses in obesity may be useful for preventing or ameliorating obesity-related pathologies. Some spice-derived components, which are naturally occurring phytochemicals, elicit antiobesity and antiinflammatory properties. In this study, we investigated whether active spice-derived components can be applied to the suppression of obesity-induced inflammatory responses. Mesenteric adipose tissue was isolated from obese mice fed a high-fat diet and cultured to prepare an adipose tissue-conditioned medium. Raw 264.7 macrophages were treated with the adipose tissue-conditioned medium with or without active spice-derived components (i.e., diallyl disulfide, allyl isothiocyanate, piperine, zingerone and curcumin). Chemotaxis assay was performed to measure the degree of macrophage migration. Macrophage activation was estimated by measuring tumor necrosis factor-alpha (TNF-alpha), nitric oxide, and monocyte chemoattractant protein-1 (MCP-1) concentrations. The active spice-derived components markedly suppressed the migration of macrophages induced by the mesenteric adipose tissue-conditioned medium in a dose-dependent manner. Among the active spice-derived components studied, allyl isothiocyanate, zingerone, and curcumin significantly inhibited the cellular production of proinflammatory mediators such as TNF-alpha and nitric oxide, and significantly inhibited the release of MCP-1 from 3T3-L1 adipocytes. Our findings suggest that the spice-derived components can suppress obesity-induced inflammatory responses by suppressing adipose tissue macrophage accumulation or activation and inhibiting MCP-1 release from adipocytes. These spice-derived components may have a potential to improve chronic inflammatory conditions in obesity.  相似文献   

20.
The effect of ouabain on the antiviral and anticellular activities of interferon and its components was tested in RSb cells. These cells were found to be inhibited in growth by both components. Ouabain, known to block the antiviral effect of interferon without affecting the growth inhibitory effect, depressed both effects of the antiviral component. The effect of the growth inhibitory component was unaltered by the drug. The results support earlier suggestions that two different mechanisms may be involved in the growth regulation by interferon.  相似文献   

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