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31.
Aurelio Serrano Patricia Giménez Siegfried Scherer Peter Böger 《Archives of microbiology》1990,153(6):614-618
The in situ location of the electron carrier protein cytochrome C
553 (cyt c
553) has been investigated in both vegetative cells and heterocysts of the cyanobacterium Anabaena variabilis ATCC 29413 using the antibody-gold technique, carried out as a post-ernbedding immunoelectron microscopy procedure. When using a rabbit polyclonal anti-cyt c
553 specific antiserum an intense labelling, associated mainly with the cell periphery (cytoplasmic membrane and periplasmic area), was seen in both heterocysts and vegetative cells. The selective release of most of the cellular cyt c
553 during a Tris-EDTA treatment confirms a periplasmic localization of this protein in A. variabilis. The results indicate that most of cyt c
553 is located in the periplasmic space. The roles ascribed to this protein in both respiration and photosynthesis in cyanobacteria are discussed.Abbreviations Cyt c
553
cytochrome c
553
- PBS
phosphate buffered saline (20 mM sodium phosphate, 0.9% NaCl, pH 7.4)
- PMSF
phenylmethylsulfonyl fluoride
Recipient of a Research Fellowship of the Alexander von Humboldt Foundation (Bonn, FRG) for a leave to the University of Konstanz. 相似文献
32.
Paul L. Wood Tadimeti S. Rao Smriti Iyengar Thomas Lanthorn Joseph Monahan Alex Cordi Eric Sun Michael Vazquez Nancy Gray Patricia Contreras 《Neurochemical research》1990,15(2):217-230
Conclusions Current neurochemical studies of the NMDA receptor macromolecular complex are yielding new insights into the interactions of the subunits of this complex and the associated potential clinical benefits of selective modulation of these subnits. Such studies offer the great potential for a new generation of pharmacotherapies for a wide range of CNS disorders, including stroke, a condition for which there is currently no effective pharmacological treatment. However, it is essential to understand that the first generation products in this area may not be optimal pharmacotherapies, such that haracterization of possible receptor subtypes and understanding the molecular biology of the component proteins of the receptor complex will be crucial in the design of the optimal pharmacological modulators of the NMDA receptor complex.Special issue dedicated to Dr. Erminio Costa 相似文献
33.
34.
Hélène Pelletier Nils-Olivier Olsson Catherine Fady Danièle Reisser Patricia Lagadec Jean-François Jeannin 《Cancer immunology, immunotherapy : CII》1988,26(3):263-268
Summary DHD/K12 TRb (PROb) and DHD/K12 TSb (REGb) are two cancer cell variants originating from the same rat colon adenocarcinoma. They differ in their tumorigenicity: when inoculated into syngeneic BDIX rats, PROb cells induce progressive tumors whereas REGb cells induce tumors which always regress. As previously described, there is an inverse relation between their tumorigenicity and their susceptibility to NCMC mediated by syngeneic spleen or peripheral blood lymphocytes: PROb cells are significantly less sensitive to NCMC than REGb cells. This suggests a role for NCMC in the regression of REGb tumors. In this work the BDIX NCMC effector cells active in vitro against REGb cells were identified as NK cells according to four criteria: (1) efficacy in a 4-h 51Cr release assay, (2) sensitivity to anti-asGM1 antibody plus complement, (3) LGL morphology, and (4) ability to bind with the same affinity REGb and YAC-1 cells. In spleen, these NK cells were heterogeneous with respect to their asGM1 surface density and their morphology. PROb cells were not lysed by these NK cells in a short-term cytotoxicity assay, but only in a 16-h assay. It was shown that PROb and REGb cells were bound with the same affinity by NK cells, thus they certainly differ in their ability to resist to NK lytic mechanisms. This difference could play a role in the different tumorigenicity of the two variants.
Abbreviations used: NK, natural killer; NC, natural cytotoxic; NCMC, natural cell-mediated cytotoxicity; asGM1, asialo GM1; LL, large lymphocytes; LGL, large grnular lymphocytes; LAL, large agranular lymphocytes; PBMNC, peripheral blood mononuclear cells; E:T, effector to target cell ratio; C:H, cold to hot cell ratio; FBS, fetal bovine serum 相似文献
35.
Long-delay learning in rats with parabrachial pontine lesions 总被引:1,自引:0,他引:1
Two experiments were conducted to test the hypothesis that ratswith lesions in the parabrachial nucleus of the pons (PbN) canacquire conditioned taste aversions only if the conditionedand unconditioned stimuli are presented close together in time.In experiment 1, rats with lesions in the medial PbN, lateralPbN or outside of the PbN (lesioned control), and unoperatedcontrol rats were trained to avoid Na-saccharin in a one-bottletest. In this procedure, a 5-min delay was imposed between the15-min Na-saccharin presentation and an injection of LiCl (0.3M, 1 % body weight, i.p.). Results showed that, after threeNa-saccharin-LiCl pairings, all rats, except the medial PbNgroup, acquired a strong aversion to Na-saccharin. In experiment2, the same rats were presented with LiCl (0.12 M) in their15-min daily access to fluid on 3 alternate days. Although ratsin the medial PbN group drank more LiCl on day 1 than rats inthe other groups, they significantly reduced their LiCl consumptionon day 2 and did not differ from other groups by day 3. Resultsare discussed in terms of possible behavioral and physiologicalmechanisms that might account for these phenomena. 相似文献
36.
The regulation of amidase synthesis inP. aeruginosa is under positive control. This review describes the experimental evolution of amidase and its regulator protein for the hydrolysis of novel substrates and experiments to elucidate the mechanism of the control system. 相似文献
37.
An alternative to the Cholodny-Went, auxin-transport hypothesis of gravitropic stem bending was proposed as early as 1958, suggesting that gravistimulation induces changes in sensitivity to auxin, accounting for differential growth and bending. To test the sensitivity hypothesis, we immersed marked, decapitated sunflower (Helianthus annuus L.) hypocotyl sections in buffered auxin solutions over a wide concentration range (0, 10−8 to 10−2 molar IAA), photographed them at half-hour intervals, analyzed the negatives with a digitizer/computer, and evaluated surface-length changes in terms of Michaelis-Menten enzyme kinetics. Bending decreases with increasing auxin concentration; above about 10−4 molar IAA the hypocotyls bend down; increasing auxin inhibits elongation growth of lower surfaces (which is high at zero or relatively low auxin levels) but promotes upper-surface growth (which is low at low auxin levels). Thus, lower surfaces have a greater Km sensitivity to applied auxin than upper surfaces. At optimum auxin levels (maximum growth), growth of bottom surfaces exceeds that of top surfaces, so bottom tissues have a greater Vmax sensitivity. Vmax sensitivity of vertical controls is slightly lower than it is for either horizontal surface; Km sensitivity is intermediate. Clearly, gravistimulation leads to significant changes in tissue sensitivity to applied auxin. Perhaps these changes are also important in normal gravitropism. 相似文献
38.
The currrent California condor (Gymnogyps californianus) recovery plan entails increasing the reproductive rate via replacement-clutch manipulation of eggs. During the period from 1983 to 1985, 15 eggs were removed from wild nesting pairs for artificial incubation. The eggs were incubated at a dry bulb temperature of 36.4°C in modified forced-air Lyon Electric incubators. The incubation humidity was adjusted for individual eggs based on weight loss data (water = weight), 25.6–30.0°C wet bulb (41.0–63.0% Relative Humidity (RH)). The chicks were hatched initially under forced-air conditions of 36.1°C dry bulb, 31.1–01.7°C wet bulb (70.0–73.0% RH). In 1984, hatching parameters were changed to still-air conditions, 36.1°C dry bulb (top of the egg), 35.0°C dry bulb (bottom of the egg), 31.1–31.7°C wet bulb (70.0-73.0% RH). Tactile and auditory stimulation was utilized during the pip-to-hatch interval. From among 15 eggs collected, 13 hatched, and 12 condor chicks were raised successfully (hatchability: 86.7%; survivability: 92.3%). 相似文献
39.
Keith C. White Patricia C. Babbitt Douglas D. Buechter George L. Kenyon 《Journal of Protein Chemistry》1992,11(5):489-494
The importance of creatine kinase (E.C. 2.7.3.2) in endocrine tissues has been generally overlooked. Using a specific radiometric assay, we have demonstrated the existence of CK in the Brockmann body (principal islet) of the Coho salmon. We have purified this protein from insular tissue and concurrently purified CK from brain and muscle of the salmon. Purification characteristics, immunological cross-reactivity, and N-terminal sequence analysis have demonstrated that the predominant cytosolic CK from the Brockmann body is indistinguishable from the BB (brain) isoenzyme. Immunocytochemical studies indicated that the enzyme resides in the endocrine parenchyma. Phosphocreatine may serve as a reservoir of energy in the islet and augment its capacity to secrete hormones. The induction of CK-BB in the islet by other hormones could influence the secretion of insular hormones. Interorgan flux of the substrate creatine may be an undescribed mechanism of physiological regulation. 相似文献
40.
Immature maize spikelets have been successfully grown in vitro. Culture conditions were refined to maximize development of normal pollen grains. Kinetin was not required for normal development, in contrast to the absolute requirement for this plant growth regulator for in vitro tassel development. Development occured in all stages sampled, from premeiosis to postvacuolation, and there was no lag in progression through the various stages of development as compared to greenhouse-grown material. Cultured spikelets produced pollen that appeared morphologically normal, accumulated starch and had the normal two sperm nuclei and single vegetative nucleus. 相似文献