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101.
Bradykinin Stimulates Phosphoinositide Hydrolysis and Mobilization of Arachidonic Acid in Dorsal Root Ganglion Neurons 总被引:11,自引:4,他引:7
Cultures of fetal rat dorsal root ganglion neurons (7 days in culture) were prelabeled with myo-[3H]inositol or [3H]arachidonic acid for 24 h and stimulated with 10 microM bradykinin for time intervals of 5-300 s. The incubation was terminated by addition of 5% perchloric acid to extract inositol phosphates or organic solvent to extract lipids. Inositol phosphates were resolved by anion-exchange HPLC; lipids were resolved by TLC. Bradykinin stimulation resulted in a 10-fold increased accumulation of inositol 1,4,5-trisphosphate (IP3) and inositol bisphosphate (IP2) (fivefold) by 5 s. The increase in IP3 was transient (half maximal by 1 min), whereas stimulated IP2 levels were sustained for several minutes. Even longer term increases were observed in inositol monophosphate. Stimulation also resulted in a threefold increase in arachidonic acid which was preceded by transient increases in diacylglycerol (twofold) and arachidonoyl-monoacylglycerol (threefold). The temporal lag in the accumulation of arachidonic acid with respect to diglyceride and monoglyceride suggested the involvement of di- and monoglyceride lipases in arachidonic acid mobilization. A role for phospholipase A2 is also possible, because pretreatment of cultures with quinacrine partially blocked arachidonic acid release. Bradykinin-stimulated arachidonic acid release was decreased in the presence of calcium channel blockers nifedipine or verapamil (50 microM), or EDTA (2.5 mM). The role of calcium was verified further in that accumulation of phosphatidic acid, diacylglycerol, and arachidonic acid was maximally stimulated by treatment with the calcium ionophore A23187 (20 microM). 相似文献
102.
Plasma membranes from corn roots (Zea mays L.) were isolated by aqueous two-phase partitioning. A fraction enriched in a vanadate-sensitive ATPase showed characteristics of a plasma membrane ATPase. The sidedness of these vesicles was 89% right-side-out, as evaluated by the ATPase latency. A NADH-ferricyanide reductase was associated with these plasma membrane vesicles. The rate of ferricyanide reduction was 1.3 μmol · min−1·mg−1 protein and was strongly enhanced by the addition of lysophosphatidylcholine (LPC). The effect of this detergent on membrane solubilization and reductase activity was particularly studied. This type of detergent treatment revealed two pH optima (7.0 and 5.0) for the reductase activity, which exhibited biphasic kinetics in the absence or presence of the detergent. These data suggest that two or more reductases could be involved. In addition, membrane vesicle solubilization and determination of ATPase and reductase latency were simultanously studied. From these experiments, it is postulated that the reductase, which exhibits an optimum pH at 7.0 and is slightly stimulated by LPC, could be located on the external side of the plasmalemma. In contrast, the reductase at pH 5.0 strongly stimulated by the detergent treatment, is probably located on the internal side of the membrane, such as the catalytic site of ATPase. Finally, a possible direct action of LPC on the enzymes, is discussed. 相似文献
103.
Pascale Andre Christian Capo Anne Marie Benoliel Michel Buferne Pierre Bongrand 《Cell biochemistry and biophysics》1990,16(1-2):13-34
Fluorescent probes are widely used to study cell structure and function. However, few reports were devoted to a quantitative analysis of the intracellular distribution of fluorescent markers. In the present work, we describe the topographical changes of surface and cytoskeletal markers on individual cells subjected to adhesive or mechanical interaction. Conjugates were prepared with a cytotoxic T-lymphocyte clone and target cells. Specific antigens, membrane phospholipids, surface glycoconjugates, and polymerized actin were labeled with fluorescent antibodies or biochemical probes. The analysis of fluorescence distributions in conjugates demonstrated a selective reorganization of the plasma membrane with a gathering of some molecular species in the intercellular adhesion area. Furthermore, individual phagocytic cells were sucked into glass micropipets, then stained with fluorescent phallacidin to analyze the effect of mechanical efforts on the cytoskeleton organization. The concentration of polymerized actin was found to be similar in mechanicallyinduced protrusions and whole cells. It is concluded that adhesive interactions may result in marked cell polarization and formation of membrane zones with a particular biochemical composition. The submembranar cytoskeleton might play a role in this process. 相似文献
104.
Marianne Horoyan Anne-Marie Benoliel Christian Capo Pierre Bongrand 《Cell biochemistry and biophysics》1990,17(3):243-256
We combined fluorescence labeling, digital image processing, and micromanipulation to investigate the intracellular events induced by inflicting a mechanical stress on rat basophilic leukemia cells. Our findings were as follows:
- Most cells displayed a localized calcium rise in response to micropipet aspiration. This represented an average threefold increase as compared to resting level, and it was observed during the first 10 s following aspiration. A slow return to initial level occurred within about 3 min. Further, this calcium rise involved a mobilization of intracellular stores, since it was not prevented by adding a calcium chelator into the extracellular medium.
- All micropipet-aspirated cells displayed a local accumulation of microfilaments, with a preferential localization in the cell protrusions or near the pipet tips.
- No absolute correlation was found between the localization of calcium rise and cytoskeletal accumulation.
- Cell deformability was decreased when intracellular calcium was maintained at a constant (high or low) level with ionomycin and/or EGTA.
105.
106.
From 1987 until 1995, life-history traits of the Lesser Sheathbill Chionis minor in the Kerguelen Archipelago were compared with those at other localities, where this species breeds in seabird colonies. At Kerguelen Island only, some pairs breed on shores free of penguin and cormorant colonies. Moreover, pairs, including nonbreeders, and solitary individuals maintain territories all the year round. Site and mate changes were not linked, and all divorces were permanent. Fidelity rates were similar in all localities and so were the annual survival rates of adults. The survival rate of immature individuals was highest at Kerguelen Island, where sheathbills laid smaller clutches, produced fewer fledglings and had lower breeding success than in the other islands. At Kerguelen Island, pairs breeding on shores had similar clutch sizes but fledged fewer offspring than those breeding in seabird colonies. Further, the proportion of vacant territories and nonbreeders was higher on shores. Kerguelen sheathbills devoted less time to food acquisition than those on Marion Island, being exceptionally kleptoparasitic, and spent a smaller part of their foraging time exploiting seabird colonies. Their diet was mainly algae. The differences on Kerguelen Island as compared with other localities were caused by the presence of an extensive intertidal zone on the former, which reduced competition, making many more sites suitable and the environment more predictable. These life-history and behavioural traits are discussed in relation to life-history theory. As differences were also found, although less extensive, within the Kerguelen Archipelago, we suggest that some traits represent an adaptive response to external constraints and that the life-history strategy of the Lesser Sheathbill is particularly opportunistic. 相似文献
107.
Olivier Cohen Christine Cans Jean Louis Gilardi Hubert Roth Marie-Ange Mermet Pierre Jalbert Jacques Demongeot Martine Cuillel 《Human genetics》1996,97(5):659-667
Reciprocal translocations (rcp) are among the most common constitutional chromosomal aberrations in man. Using a European
database of 1574 families carrying autosomal rcp, a cartographic study was done on the breakpoints involved. The breakpoints
are non-randomly distributed along the different chromosomes, indicating “hot spots”. Breakpoints of rcp that result in descendants
that are unbalanced chromosomally at birth are more frequent in a distal position on chromosomal arms, and 65% of them are
localised in R-bands. Among the R-bands, bands rich in GC islands and poor in Alu repetitive sequences are more frequently
the site of breakpoints, as well as bands that include a fragile site. This result suggests that the variation in degree of
methylation in GC islands could be involved in chromosomal breakage and hence in chromosomal rearrangements.
Received: 10 April 1995 / Revised: 1 July 1995 相似文献
108.
Maria de Fatima Bonaldo Pierre Jelenc Long Su Lee Lawton M. -T. Wu Dorothy Warburton Marcelo Bento Soares 《Human genetics》1996,97(4):441-452
A study was conducted on the feasibility of isolating genes and pseudogenes that map to chromosome 13 by a hybridization-based approach using a 13-specific library and pools of repeat-free cDNA clones. Five pairs of cDNA and chromosome 13 genomic clones were identified and characterized. Partial or full-length sequence was derived from all cDNAs, and database searches were performed for putative gene identification. Partial sequence was also obtained from the chromosome 13 genomic clones for comparison with those of the hybridizing cDNAs. As a result of these analyses we identified three genes, a putative homologue of a porcine mRNA encoding an unidentified hepatic protein, a putative homologue of a yeast integral membrane protein, and a gene for a translationally controlled tumor protein, and two processed pseudogenes, ribosomal proteins L23a and S3a. The latter was formerly identified as the v-fos transformation effector gene, Fte-1, and recently cited as a possible candidate for the BRCA2 gene on chromosome 13. All genes and pseudogenes were localized to cytogenetic bands by in situ hybridization of metaphase chromosomes with probes derived from the chromosome 13 genomic clones. 相似文献
109.
We review some of the older literature concerning metabolic turnover of cholesterol in the nervous system. The overall picture
is that incorporation of radioactive precursors into brain cholesterol is roughly proportional to the rate of myelination
and that, once incorporated, radioactive cholesterol is relatively stable metabolically. We outline a strategy for demonstrating
the source (local synthesis or uptake from the circulation) of cholesterol in brain. The experimental design involves determining
the rate of accumulation of cholesterol this is calculated as the increasing amounts of sterol in brain at successive time
intervals during development. The rate of appearance of newly synthesized cholesterol is determined from incorporation of
radioactivity from3H2O (injected i.p. several hours prior to sacrifice) into cholesterol. The radioactivity associated with the sterol fractions
and the specific activity of body water determined from the serum can be used to calculate the absolute amount of sterol newly
synthesized during the time when3H2O was present. The results obtained demonstrated that all of the bulk cholesterol accumulating in brain can be accounted for
by newly synthesized cholesterol. None of the radioactive cholesterol came from the circulation, since cholesterol feeding
suppressed cholesterol biosynthesis in the liver and specific radioactivity of circulating cholesterol was negligible. Thus,
almost all cholesterol accumulating in brain during development is locally synthesized.
Special issue dedicated to Dr. Marion R. Smith. 相似文献
110.
Josiane Arnaud Pierre Bourlard Bernard Denis Alain E. Favier 《Biological trace element research》1996,53(1-3):129-136
This study was carried out to assess manganese (Mn) status after an acute episode of myocardial infarction. Plasma and erythrocyte
Mn concentrations were measured from admission to hospital to day 15 postadmission in 21 patients suffering from acute myocardial
infarction and in three control groups. The determination of Mn in these biological fluids was performed by electrothermal
atomic absorption spectrometry. Plasma Mn was higher (p<0.01) and erythrocyte Mn was similar in the acute myocardial infarction group compared to healthy age-matched control group.
Plasma and erythrocyte Mn remained unchanged during the 2 wk after acute myocardial infarction and were not correlated to
enzyme activities. A decrease of erythrocyte Mn with age, expressed in nmol/L, was noted (p<0.02). These results suggest that plasma and erythrocyte Mn do not provide an indication of myocardial damage. Nonetheless,
Mn status in elderly merits further attention. 相似文献