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131.
大鼠缰核与下丘脑外侧区在调节心血管活动方面的机能联系 总被引:6,自引:0,他引:6
电刺激大鼠下丘脑外侧区(LH),动脉压明显升高,心率加快,在刺激电极同侧缰核(Hb)内微量注射盐酸利多卡因、电刺激LH引起的升压反应可被阻断38.9%,心率增快反应可被阻断44.4%,双侧Hb内微量注射盐酸利多卡因,电刺激LH引起的升压反应可被阻断40.7%,心率增快反应可被阻断41.2% ,单侧或双侧Hb内微量注射人工脑脊液均不能阻断电刺激LH引起的心血管反应。电刺激大鼠Hb,动脉压明显升高,心率无明显改变,在刺激电极同侧LH内微量注射盐酸利多卡因,电刺激Hb引起的升压反应可被阻断63.2%,双侧LH内微量注射盐酸利多卡因,电刺激Hb引起的升压反应可被阻断62.6%,单侧或双侧LH内微量注射人工脑脊液均不能阻断电刺激Hb引起的心血管反应。本实验提示Hb与LH在调节心血管活动方面有协同作用。 相似文献
132.
W. J. J. van den Tweel M. N. Widjojoatmodjo J. A. M. de Bont 《Archives of microbiology》1988,150(5):471-476
Thirteen bacteria were isolated on D-4-hydroxyphenylglycine as sole carbon and energy source. Seven strains transaminated only the D-enantiomer while the other six isolates transaminated both enantiomers of 4-hydroxyphenylglycine. One of the six strains utilizing both enantiomers was characterized as a Pseudomonas putida. This strain, MW27, employed two enantioselective transaminases, to catalyze the initial step in the metabolism of DL-4-hydroxyphenylglycine. The product of the transamination, 4-hydroxyphenylglyoxylate, was further metabolized via 4-hydroxybenzaldehyde and 4-hydroxybenzoate to protocatechuate. Preliminary results indicate that both transaminases are co-ordinately synthesized together with the 4-hydroxyphenylglyoxylate decarboxylase and the NADP+-dependent 4-hydroxybenzaldehyde dehydrogenase. 相似文献
133.
A degradation pathway for dl--phenylhydracrylic, phenylacetic, 3- and 4-hydroxyphenylacetic acid by a Flavobacterium is presented. Experiments with washed cells and enzyme studies revealed that dl--phenylhydracrylic acid in an initial reaction was oxidatively decarboxylated to phenylacetaldehyde. Whole cells oxidized both stereoisomers of phenylhydracrylic acid at different rates. The product phenylacetaldehyde in turn was oxidized to phenylacetic acid. No hydroxylation of phenylacetic acid was detected in cell extracts, but on the basis of experiments with washed cells it is assumed that phenylacetic acid is mainly metabolized via 3-hydroxyphenylacetic acid. This latter product was subsequently hydroxylated yielding the ring-cleavage substrate homogentisate. 4-Hydroxyphenylacetic acid was also degraded via homogentisate. Ringcleavage of homogentisate gave maleylacetoacetate which was further degraded through a glutathione-dependent pathway. Homoprotocatechuate was not an intermediate in the metabolism of dl-phenylhydracrylic acid, phenylacetic, 3- and 4-hydroxyphenylacetic acid metabolism, but it could be hydroxylated aspecifically to 2,4,5-trihydroxyphenylacetic acid by the action of the 3-hydroxyphenylacetic acid-6-hydroxylase.Abbreviations HPLC
high-performance liquid chromatography
- PHA
phenylhydracrylic acid
- PA
phenylacetic acid
- HPA
hyxdroxyphenylacetic acid
- PMS
phenazine methosulphate
- PMA
phenylmalonic acid
- GSH
glutathione 相似文献
134.
Anaerobic bacteria degrading 2-methoxyethanol were enriched from freshwater sediments, and three strains were isolated in pure culture. Two of them were Grampositive non-spore-forming rods and grew strictly anaerobically by acetogenic fermentation. Optimal growth occurred at 30°C, initial pH 7.5–8.0. 2-Methoxyethanol and 2-ethoxyethanol were fermented to acetate and corresponding alcohols. Hydrogen plus carbon dioxide, formate, acetoin, l-malate, lactate, pyruvate, fructose, and methoxyl groups of 3,4,5-trimethoxybenzoate and 3,4,5-trimethoxycinnamate were fermented to acetate. 1,2-Propanediol was fermented to acetate, propionate, and propanol. Strain MuME1 was described as a new species, Actetobacterium malicum. It had a DNA base composition of 44.1 mol% guanine plus cytosine. The third strain, which was identified as Pelobacter venetianus, fermented 2-methoxyethanol to methanol, ethanol, and acetate. 相似文献
135.
The -galactosidase (EC 3.2.1.32) of Corynebacterium murisepticum (inducible by lactose and galactose) was purified by successive column chromatography on Sephadex G-200, DEAE-Sephadex A-50 and DEAE-cellulose (DE52). The enzyme was found to be a dimer of identical subunits of molecular mass 100,000 daltons. The K
m values of the enzyme for the substrates lactose and o-nitrophenyl--d-galactopyranoside (ONPG) are 16.7 mM and 4.4 mM, respectively, indicating, its low affinity for the substrates. The Ouchterlony immunodiffusion method exhibited immunological homogeneity of the enzyme preparation. The catalytic site of the enzyme does not take part in antigen-antibody reaction. 相似文献
136.
137.
The in vitro and ex vivo effects of antidepressant drugs on membrane-bound phosphatidylinositol (PI) synthetase and PI: myo-inositol exchange enzyme activities were examined. In rat brain subcellular fractions, PI synthetase occurred exclusively in the microsomes. In comparison, the activity of CDP-diglyceride independent PI: myo-inositol exchange enzyme was low (3%). Of the various CDP-diglycerides tested for the activation of PI synthetase, CDP-dipalmitin was the most active. Addition of 1 mM of desipramine, amitriptyline, imipramine, iprindole, clomipramine and mianserin in vitro significantly inhibited (30–60%) PI synthetase activity, whereas the same concentration of zimelidine and fluoxetine had no effect. At low liponucleotide concentrations, PI synthetase activity was significantly enhanced by imipramine (1 mM), whereas the enzyme activity was inhibited at higher liponucleotide concentrations (>0.3 mM). In contrast, imipramine had no effect on the PI: myo-inositol exchange enzyme activity. No significant alteration in the PI synthetase activity was found following either acute (2 h) or chronic (21 d) treatment of rats with imipramine. The above results indicate that the de novo synthesis of PI is inhibited in vitro but not ex vivo by some antidepressant drugs. However, in view of the high concentration of the drugs required, the pharmacological significance of this inhibitory action with respect to their therapeutic effects is doubtful. 相似文献
138.
Bruce Vondracek Wayne A. Wurtsbaugh Joseph J. Cech 《Environmental Biology of Fishes》1988,21(1):45-57
The allocation of energy to growth and reproduction, in relation to temperature and food availability, was investigated in
laboratory experiments with the mosquitofish,Gambusia affinis. At constant temperature of 20, 25 and 30°C and ad libitum feeding, specific growth rates increased with increasing temperature
at 1.7, 3.1 and 3.4% dry mass day−1, respectively. Growth rates in a cycling temperature regime (20–30°C,
) were faster than in a 25°C constant temperature. As temperature increased from 20 to 30°C, mean age at first reproduction
decreased from 191 to 56 days and brood size and mass of offspring increased significantly. Interbrood interval was also temperature
dependent; estimates at 25 and 30°C for females >1000 mg were 22.6 and 18.6 days, respectively. Interbrood interval could
not be calculated at 20°C. Although fitness was highest at 30°C, females at 25°C invested a greater proportion of surplus
energy (growth and reproduction) to reproduction (38%) than at 20 (17%) or 30°C (36%) during the 32-week study. Fish at cooler
temperatures began reproduction at a smaller size.
Where rations were controlled at low, medium, and ad libitum levels, somatic and gonadal growth increased with increasing
temperatures and food availability. The proportion of energy invested in reproduction was highest at 25°C for each comparable
ration level. Calculated energy budgets indicated that over the 10-week study, 17–22% of the food energy was invested in growth,
0–7% in reproduction, and 75–83% in respiration and excretory losses, depending on feeding and temperature conditions. 相似文献
139.
Martina Weber 《Plant Systematics and Evolution》1988,161(1-2):53-64
The formation of sperm cells has been examined ultrastructurally in the tricellular pollen grains ofGalium mollugo L. (Rubiaceae).Trichodiadema setuliferum
Schwantes (Aizoaceae), andAvena sativa L. (Poaceae). After detachement from the intine the generative cell of all three species lies free within the vegetative cytoplasm. The two sperm cells are built inTrichodiadema andAvena by a single separating wall, while inGalium mollugo two independent walls are formed. However, both mechanisms separate the two male gametes completely. 相似文献
140.
The possibility that plant growth regulators may relate to a cyclic 3:5 adenosine monophosphate (cAMP)-dependent protein kinase through the control of cAMP level in the conidial germination process of Neurospora crassa was examined using a cAPM-dependent protein kinase mutant (cpk mutant) which is thought to be cAMP-independent because of defect in the regulatory subunit of cAMP-dependent protein kinase. IAA, 2,4-D and GA3 promoted conidial germination and elongation of young hyphae in the mutant as well as in the wild-type. The result suggests that the effects of auxin and gibberellin on germination and hyphal elongation are not mediated by cAMP. 相似文献