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31.
Magdalena Torres M. France Bader Dominique Aunis M. Teresa Miras-Portugal 《Journal of neurochemistry》1987,48(1):233-235
Chromaffin cells both recently isolated or in culture present a high-affinity adenosine transporter with a Km value of 1 microM. When cells were exposed to nerve growth factor (NGF; 10 ng/ml), the adenosine transporter affinity decreased to 3 microM. This value was maintained from 3 days after plating to the end of the culture period. A change in the transport capacity was observed, with a significant increase (approximately 200-260%) in NGF-cultured cells throughout the period studied. 相似文献
32.
R H Oltmanns R Müller M K Otto F Lingens 《Applied and environmental microbiology》1989,55(10):2499-2504
Six bacterial strains able to use 4-fluorobenzoic acid as their sole source of carbon and energy were isolated by selective enrichment from various water and soil samples from the Stuttgart area. According to their responses in biochemical and morphological tests, the organisms were assigned to the genera Alcaligenes, Pseudomonas, and Aureobacterium. To elucidate the degradation pathway of 4-fluorobenzoate, metabolic intermediates were identified. Five gram-negative isolates degraded this substrate via 4-fluorocatechol, as described in previous studies. In growth experiments, these strains excreted 50 to 90% of the fluoride from fluorobenzoate. Alcaligenes sp. strains RHO21 and RHO22 used all three isomers of monofluorobenzoate. Alcaligenes sp. strain RHO22 also grew on 4-chlorobenzoate. Aureobacterium sp. strain RHO25 transiently excreted 4-hydroxybenzoate into the culture medium during growth on 4-fluorobenzoate, and stoichiometric amounts of fluoride were released. In cell extracts from this strain, the enzymes for the conversion of 4-fluorobenzoate, 4-hydroxybenzoate, and 3,4-dihydroxybenzoate could be detected. All these enzymes were inducible by 4-fluorobenzoate. These data suggest a new pathway for the degradation of 4-fluorobenzoate by Aureobacterium sp. strain RHO25 via 4-hydroxybenzoate and 3,4-dihydroxybenzoate. 相似文献
33.
Teresa Urbanik-Sypniewska Ulrich Seydel Michaela Greck Jürgen Weckesser Hubert Mayer 《Archives of microbiology》1989,152(6):527-532
The structure of the lipopolysaccharide from Rhizobium meliloti 10406, a derivative of the wild-type strain MVII-1, was examined. The compositional analysis of its polysaccharide moiety demonstrated lack of heptose(s), but high contents in glucose, galacturonic acid and 2-keto-3-deoxy-octonate (dOclA) as characteristic features. The lipid A moiety consisted of a -1,6 linked glucosamine disaccharide carrying ester (at C-4) and glycosidically (at C-1) linked phosphate residues, both present exclusively as monoester phosphates but not as phosphodiesters. Ester- and amidelinked 3-hydroxy fatty acids were mostly present as non-3-O-acylated residues. Laser desorption mass spectrometry (LD-MS) revealed heterogeneity in the fatty acid substitution, as was also indicated by the non-stoichiometric ratios obtained by quantitative fatty acid analysis. The predominating lipid A structure contained at the reducing glucosamine residue ester-linked 3-hydroxy-tetradecanoic acid (3-OH-14:0) and amide-linked 3-OH-18:0, or 3-OH-18:1, respectively. The distal (non-reducing) glucosamine carried ester-bound the recently discovered 27-hydroxyoctacosanoic acid and 3-OH-14:0 and, as amide-linked fatty acid, mostly 3-hydroxy-stearic acid (3-OH-18:0).The isolated lipopolysaccharide exhibited a high extent of lethal toxicity in galactosamine-treated mice, comparable to that of enterobacterial lipopolysaccharide. The structural relationship of LPS and lipid A of Rhizobium meliloti to other rhizobial lipopolysaccharides and lipid A's with respect to questions of taxonomy and of phylogenetic relationships will be discussed.Abbreviations LPS
lipopolysaccharide
- dOclA
3-deoxy-D-mannooctulosonic acid (KDO)
- GalA
galacturonic acid
- DOC
sodium deoxycholate
- PAGE
polyacrylamide gel electrophoresis
- LD-MS
laser desorption-mass spectrometry 相似文献
34.
Six bacterial strains able to use 4-fluorobenzoic acid as their sole source of carbon and energy were isolated by selective enrichment from various water and soil samples from the Stuttgart area. According to their responses in biochemical and morphological tests, the organisms were assigned to the genera Alcaligenes, Pseudomonas, and Aureobacterium. To elucidate the degradation pathway of 4-fluorobenzoate, metabolic intermediates were identified. Five gram-negative isolates degraded this substrate via 4-fluorocatechol, as described in previous studies. In growth experiments, these strains excreted 50 to 90% of the fluoride from fluorobenzoate. Alcaligenes sp. strains RHO21 and RHO22 used all three isomers of monofluorobenzoate. Alcaligenes sp. strain RHO22 also grew on 4-chlorobenzoate. Aureobacterium sp. strain RHO25 transiently excreted 4-hydroxybenzoate into the culture medium during growth on 4-fluorobenzoate, and stoichiometric amounts of fluoride were released. In cell extracts from this strain, the enzymes for the conversion of 4-fluorobenzoate, 4-hydroxybenzoate, and 3,4-dihydroxybenzoate could be detected. All these enzymes were inducible by 4-fluorobenzoate. These data suggest a new pathway for the degradation of 4-fluorobenzoate by Aureobacterium sp. strain RHO25 via 4-hydroxybenzoate and 3,4-dihydroxybenzoate. 相似文献
35.
Teresa Duda Stephen Chalberg Rameshwar K. Sharma 《Molecular and cellular biochemistry》1990,92(1):69-75
Summary A complementary DNA (cDNA) clone - cA2-47 - corresponding to a new 2-adrenergic receptor subtype has been isolated from a rat brain cDNA library and used as a hybridization probe to scrutinize the 2-receptor poly(A+) RNAs in rat brain, heart and adrenal gland. Hybridization of the 5 half of the coding region of this cDNA at 37°C to rat brain poly(A+) RNA revealed a single band at 5.8 kb as the size of its corresponding mRNA. Under identical hybridization conditions, a human platelet 2-receptor genomic probe failed to hybridize to any rat brain mRNAs.Under lower stringency conditions, hybridization of the full-length cDNA, cA2-47, to selected rat tissue poly(A+) RNA showed the presence of four different sized mRNAs in brain and three in both heart and adrenal gland. Messages of 1.3 kb and 2.1 kb were common in all three tissues (although the band at 2.1 kb was slightly higher in the heart and adrenal gland). A 5.8 kb mRNA was unique to the brain and a slightly higher band at 6.0 kb was consistently present in heart and adrenal gland but was absent in the brain. A fourth message at 3.4 kb was found predominantly in the brain and was either absent or present at very low levels in the other tissues examined. Under the same conditions, a human platelet 2-receptor probe hybridized to similar sized messages of 2.1 and 5.8 kb in rat brain and 2.2 and 6.0 kb in rat heart and adrenal gland. This probe, however, failed to detect the abundant 1.3 kb mRNA common to all tissues or the 3.4 kb message in rat brain. The extent of homology of these messages with cA2-47 is not confined to limited regions of the cDNA since similar hybridization patterns were observed using either 5-noncoding or 5-coding regions of the probe.These results provide the first direct evidence of a surprisingly large range of mRNA sizes for members of the 2-receptor family in brain, heart, and adrenal gland. The unique nature of certain members of the family in each of the tissues examined raises the curious possibility that these members might contribute to some of the individualized functions of the brain, cardiovasculature and adrenal gland. 相似文献
36.
Dale D. Brown Ronald G. Knowlton Joseph Hamill Teresa L. Schneider Ronald K. Hetzler 《European journal of applied physiology and occupational physiology》1990,60(3):179-182
The purpose of this study was to compare the physiological and biomechanical responses of wheelchair-dependent persons (WCD) to able-bodied persons (AB) during manual wheelchair ergometry. Five WCD and five AB performed a discontinuous wheelchair ergometer test starting at 12.8 W at 30 rev.min-1 (57 m.min-1) with increments of 7.0 W at 6-min intervals. Biomechanical data were collected 3.5 min into each stage followed by the collection of physiological data. After the fifth stage, peak oxygen consumption was determined by having the subject work against a resistance of 14.7-19.6 N at 30 rev.min-1. The WCD had significantly higher net mechanical efficiency at 26.7, 33.6 and 40.6 W in comparison to the AB. The WCD had significantly greater shoulder extension at the point of initial wheel contact as measured by the shoulder angle, while the AB had significantly greater shoulder range of motion at all work rates in comparison to the WCD. The results demonstrate that a significant physiological difference exists in the manner by which WCD and AB accomplish wheelchair ergometry. The biomechanical differences between AB and WCD were found to be a prominent factor contributing to the higher mechanical efficiency of WCD over AB. It was concluded that basic physiological and biomechanical differences exist between WCD and AB in manual wheelchair locomotion and that these differences are important considerations to the interpretation of data in wheelchair ergometry studies. 相似文献
37.
38.
The systemic injection of kainic acid (KA) has been shown to destroy neurons in the hippocampus and to induce limbic-type seizure activity. However, little is known on the neurochemical events that are associated with this convulsant effect. In the present work we studied the spontaneous and the K+-stimulated release of labeled -aminobutyric acid (GABA), glutamate, serotonin and dopamine, in hippocampal slices of KA-treated rats, at the moment of clinical seizures (2 h) and 72 h later. At the onset of convulsions we found a 40–45% decrease in the K+-stimulated release of GABA. The release of the other neurotransmitters was not significantly affected by KA treatment. After 72 h GABA release was still reduced by 30–40%. It is concluded that the epileptogenic effect of KA in the hippocampus is probably related to a diminished inhibitory GABAergic neurotransmission. 相似文献
39.
Teresa Thiel 《Archives of microbiology》1988,149(5):466-470
The amino acid leucine was transported by the cyanobacterium Anabaena variabilis. The K
m for transport was 10.8 M; the V
max was 8.7 nmoles min–1 mg–1 chlorophyll a. Transport of leucine was energy dependent: uptake of leucine was inhibited in the dark, and by DCMU and cyanide. Transport was neither dependent on nor enhanced by Na+. Prior growth of cells with leucine did not repress transport of [14C]-leucine. Alanine, glycine, valine, and methionine were strong competitive inhibitors of leucine uptake; serine, threonine, isoleucine, norleucine, and d-alanine competitively inhibited to a lesser degree. Other amino acids or amino acid analogues, including d-leucine, -aminoisobutyrate, and d-serine did not inhibit the transport of leucine.Abbreviations Chl a
chlorophyll a
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- TES
N-tris(hydroxymethyl)-2-aminoethane-sulfonic acid
- TCA
trichloroacetic acid
- Tris
N-tris(hydroxymethyl)aminoethane 相似文献
40.
Janusz Janiszewski Dietmar Otto 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,162(6):739-746
1. | Intracellular recordings of suboesophageal neurons were performed in the cricketGryllus bimaculatus during applied changes of head temperature in the range 8 to 32.5 °C. The temperature was controlled by perfusing the head with Ringer solution of appropriate temperature. Subsequent staining with Lucifer Yellow revealed descending, ascending or T-shaped cells with ventrally located somata (Fig. 1). |
2. | In 6 out of 7 neurons recorded (Fig. 1, neurons A, B, C, D, E, G) the firing rate was correlated with abdominal ventilatory pumping (Fig. 2a, b). These neurons also received input from cereal sensory hairs (Fig. 2c). Furthermore, one of them (Fig. 1, neuron A) showed responses to auditory (Fig. 2d) and another (Fig. 1, neuron E) to visual input (Fig. 2e). |
3. | Activity of every tested neuron was correlated with the temperature of the perfusing Ringer solution: the amplitude and duration of spikes and excitatory postsynaptic potentials increased with cooling (Fig. 3). Two types of temperature-dependent changes in firing rate were identified. In type I the spiking rate was higher at higher temperature (Figs. 4a, b; 5). In type II spiking rate was related to the direction of temperature change (Fig. 4c, d). |
4. | The possible involvement of one of the recorded cells (Fig. 1, neuron F) in thermoreception processes is discussed. Activity of this neuron was not related to the rhythm of abdominal ventilatory pumping, nor did the cell receive cereal, visual or auditory input. Its activity was related mainly to the direction of temperature changes i.e. with an increase in firing rate during cooling, independent of the temperature at which the cooling started and with a transient decrease in firing rate during warming from starting point of 10 °C. |