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41.
IgM rheumatoid factor autoantibody and immunoglobulin-producing precursor cells in the bone marrow of humans 总被引:2,自引:0,他引:2
S Fong T A Gilbertson R J Hueniken S K Singhal J H Vaughan D A Carson 《Cellular immunology》1985,95(1):157-172
The natures of the IgM rheumatoid factor (RF)-, IgM-, and IgG-secreting cells in the human bone marrow as compared to the peripheral blood, have been investigated by (1) response to the polyclonal B-cell activator, the Epstein-Barr virus (EBV), (2) sensitivity to the S-phase specific antimetabolite hydroxyurea, (3) presence of the BA-1 and Ia antigens on the cell surface, and (4) cell size, as determined by counter flow elutriation. The EBV-inducible bone marrow IgM-RF precursors derived from medium to large B cells that were inhibited by hydroxyurea pretreatment. The marrow total IgM response derived from small to medium size cells, and was only partially inhibited by hydroxyurea. Hydroxyurea had no effect on IgM-RF or IgM synthesis by peripheral blood cells. These results indicate that the marrow EBV-induced IgM-RF response is not representative of the response by peripheral blood cells, moreover; the marrow RF secreting response arises from a dividing cell pool that may represent newly generated autoreactive B cells. 相似文献
42.
Dependence of phytoplankton assimilation quotients on light and nitrogen source: implications for oceanic primary productivity 总被引:1,自引:0,他引:1
Megard R. O.; Berman T.; Curtis P. J.; Vaughan P. W. 《Journal of plankton research》1985,7(5):691-702
Photosynthetic production of oxygen by phytoplankton assemblagedominated by Peridinium in Lake Kinneret, Israel, generallyexceeds the molar equivalent rate of carbon assimilation. Carbonassimilation occurs only if oxygenic photosynthesis exceedsa light-dependent threshold. Assimilation quotients (mol C molO21) are a variable function of irradiance, and typicallyonly about one-half of the photoreductant produced during oxygenicphotosynthesis is used for reduction of carbon dioxide. Mostof the residual oxygenic photoreductant probably is used forlight-dependent reduction of nitrate, which competes with carbondioxide for oxygenic photoreductant. Nitrate is an importantsource of nitrogen for this algal assemblage, and light-dependentnitrate reduction probably is much larger than carbon dioxidereduction at lowest irradiances in the euphotic zone. Oxygenproduction also may be much larger than carbon assimilationat low light levels in other environments where oxidized formsof nitrogen are important nitrogenous nutrients for phytoplankton,as in the lower euphotic zone of the sea, where low rates ofcarbon assimilation by phytoplankton have been thought to beinconsistent with the amount of oxygen that accumulates duringsummer. 相似文献
43.
Javier G. Fernández Velasco Norma L. Pucheu Oscar Romero Norma L. Kerber Raúl A. Fernández Augusto F. García 《Archives of microbiology》1985,143(2):192-195
The conditions under which an oscillatory behaviour is observed during net hydrolysis or synthesis of ATP in chromatophores of Rhodospirillum rubrum FR1 are described. In the case of ATPase the oscillations are observed at low temperature (ca. 11°C) in the dark after an initial transient behaviour. These oscillations are attenuated or disappear by the addition of an uncoupler.Oscillations are also observed during ATP synthesis. At 3°C the oscillations appear spontaneously if photophosphorylation is measured during a sufficiently long time. At 30°C the mere intercalation of a dark period also at 30°C is sufficient to trigger the oscillations in the following light period.Abbreviations Bchl
Bacteriochlorophyll
- FCCP
carbonyl cyanide p-trifluoromethoxyphenyl hydrazone
- PMS
phenazine methosulfate
- TMPD, N,N,N,N
tetramethyl-1,4-phenylenediamine
Dedicated to Prof. Dr. Gerhart Drews as a homage for his permanent example as hard worker and careful scientist and also for his remarkable human quality 相似文献
44.
Francisco Romero Francisco Javier Caballero Francisco Castillo José Manuel Roldán 《Archives of microbiology》1985,143(2):111-116
Anti-glutamine synthetase serum was raised in rabbits by injecting purified glutamine synthetase (GS) of the phototrophic bacterium Rhodopseudomonas capsulata E1F1. The antibodies were purified to monospecificity by immunoaffinity chromatography in GS-sepharose gel. These anti-GS antibodies were used to measure the antigen levels in crude extracts from bacteria, grown phototrophically with dinitrogen, nitrate, nitrite, ammonia, glutamate, glutamine or alanine as nitrogen sources. The amount of GS detected by rocket immunoelectrophoresis was proportional to Mn2+-dependent transferase activity measured in the crude extracts. Addition of GS inhibitor l-methionine-d,l-sulfoximine (MSX) to the actively growing cells promoted increased antigen levels, that were not found in the presence of glutamine or chloramphenicol. The ammonia-induced decrease in GS relative levels was reverted by MSX. GS levels remained constant when phototrophically growing cells were kept in the dark.Abbreviations GS
glutamine synthetase
- MOPS
2-(N-morpholine) propane sulfonate
- MSX
l-methionine-d,l-sulfoximine 相似文献
45.
M. K. Vaughan G. C. Brainard R. J. Reiter 《International journal of biometeorology》1984,28(3):201-210
Adult male Syrian hamsters were subjected to 1, 3, 5, 7 or 11 weeks of either natural winter conditions or rigorously controlled laboratory conditions (LD 1014; 22 ± 2C). Although both groups of hamsters gained weight over the course of the experiment, hamsters housed indoors were significantly heavier after 5 weeks of treatment compared to their outdoors counterparts. Animals housed under natural conditions exhibited a significant decrease in circulating levels of thyroxine (T4) and a rapid rise in triiodothyronine (T3) levels; the free T4 and free T3 index (FT4I and FT3I) mirrored the changes in circulating levels of the respective hormones. Laboratory-housed animals had a slight rise in T4 and FT4I at 3 weeks followed by a slow steady decline in these values; T3 and FT3I values did not change remarkably in these animals. Plasma cholesterol declined steadily over the course of the experiment in laboratory-maintained animals but increased slightly during the first 5 weeks in animals under natural conditions. Since the photoperiodic conditions were approximately of the same duration in these 2 groups, it is concluded that the major differences in body weight, thyroid hormone values and plasma cholesterol are due to some component (possibly temperature) in the natural environment. 相似文献
46.
Chromatographic behavior of cyclic AMP dependent protein kinase and its subunits from Dictyostelium discoideum 总被引:1,自引:0,他引:1
An adenosine cyclic 3',5'-monophosphate (cAMP) dependent protein kinase has recently been shown to exist in Dictyostelium discoideum and to be developmentally regulated. In this report we have followed the chromatographic behavior of both the holoenzyme and its subunits. A cAMP-dependent holoenzyme could be obtained from the 100000 g soluble fraction after passage through DE-52 cellulose (pH 7.5) and Sephacryl S300. Under conditions of low pH the holoenzyme could be further purified by flat-bed electrofocusing (pI = 6.8). Application of the holoenzyme to electrofocusing at high pH resulted in dissociation of the holoenzyme into a cAMP binding component (pI = 6.1) and a cAMP-independent catalytic activity (pI = 7.4). Dissociation of the holoenzyme into subunits also occurred during histone affinity chromatography and gel filtration chromatography (S300) in the presence of a dissociating buffer. Although the subunit structure was clearly evident during chromatography, the holoenzyme could not be dissociated by simple addition of cAMP to the extract. The catalytic subunit could be purified further by CM-Sephadex, DE-52 cellulose (pH 8.5), histone affinity, and hydrophobic chromatography. The regulatory subunit was further purified by DE-52 cellulose (pH 8.5) and cAMP affinity chromatography. Proof that the cAMP binding activity and the cAMP-independent catalytic activity were in fact the regulatory and catalytic subunits was shown by reconstitution of the cAMP-dependent holoenzyme from the purified subunits. By using these separation procedures, one can obtain from extracts of Dictyostelium the subunits that are free of each other as well as free of any endogenous protein substrates. 相似文献
47.
The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet thylakoids was examined using three different detergent-electrophoresis systems. On a per chlorophyll basis, manganese deficiency reduced the amounts of CPa complex (separated by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis), and CP 47 and CP 43 complexes (separated by octylglucoside/SDS-polyacrylamide gel electrophoresis) without decreasing the amounts of light harvesting complexes. Lithium dodecylsulfate/Triton X-100 polyacrylamide gel electrophoresis showed that manganese deficiency decreased several thylakoid polypeptides, including a chlorophyll b containing 30 kilodalton chlorophyll-protein complex, but did not decrease the amounts of 28 and 29 kilodalton light-harvesting chlorophyll b-containing polypeptides. 相似文献
48.
Selective regulation by pertussis toxin of insulin-induced activation of particulate cAMP phosphodiesterase activity in 3T3-L1 adipocytes 总被引:8,自引:0,他引:8
M L Elks P A Watkins V C Manganiello J Moss E Hewlett M Vaughan 《Biochemical and biophysical research communications》1983,116(2):593-598
Incubation of 3T3-L1 adipocytes with insulin or isoproterenol for 10 min increased particulate "low Km" cAMP phosphodiesterase activity by 42% and 50%, respectively. Pertussis toxin catalyzed the [32P]-ADP ribosylation of a 41,000 dalton protein in adipocyte particulate fractions; prior incubation of adipocytes with toxin markedly reduced incorporation of radiolabel. Exposure of adipocytes to pertussis toxin (0.3 microgram, 18 hr) increased glycerol production and inhibited activation of cAMP phosphodiesterase by insulin, but not by isoproterenol. These results suggest that pertussis toxin can interfere with receptor-mediated processes that stimulate cAMP hydrolysis as well as those that inhibit cAMP formation. 相似文献
49.
Confluent 3T3-L1 fibroblasts incubated for 72 h with methylisobutylxanthine, dexamethasone, and insulin differentiate and acquire phenotypic characteristics of mature adipocytes, including hormone-sensitive cAMP phosphodiesterase activity located in a particulate fraction of homogenates. About 10 days after initiating differentiation, a maximally effective concentration of insulin (100 pM) increased particulate cAMP phosphodiesterase activity 40 to 60% in 8 min; activation persisted for at least 30 min in the presence of insulin. Incubation of adipocytes for 6-8 min with agents that increased cAMP, e.g. 1 microM epinephrine, 0.1 microM isoproterenol, corticotropin (2 mu units/ml), or thyroid-stimulating hormone (15 ng/ml), also increased particulate phosphodiesterase activity 40-60%. Changes in phosphodiesterase activity produced by epinephrine tended to lag behind changes in cAMP. Insulin, epinephrine, and corticotropin increased Vmax, not Km (0.5 microM), for cAMP. Particulate phosphodiesterase activity, solubilized with detergent, eluted in a single peak from DEAE-Bio-Gel. Insulin and epinephrine increased the activity eluted in this peak. Neither insulin nor lipolytic hormones increased activity in soluble fractions from differentiated cells or particulate or soluble fractions from undifferentiated cells. Incubation of adipocytes for 48 h with 1 microM dexamethasone prevented insulin-induced activation of the particulate phosphodiesterase and did not alter basal activity. After incubation for 72 h with 0.1 microM dexamethasone, insulin and epinephrine activation were abolished. These effects of dexamethasone on hormonal regulation of particulate phosphodiesterase activity could account for some of the so-called permissive effects of glucocorticoids on cAMP-mediated processes as well as the "anti-insulin" effects of glucocorticoids. 相似文献
50.
In neuroblastoma-glioma (NG108-15) hybrid cells, opiates inhibit adenylate cyclase and stimulate a low Km GTPase. It has been postulated that the stimulation of GTPase plays a role in opiate inhibition of adenylate cyclase (Koski, G., and Klee, W. A. (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 4185-4189). Treatment of NG108-15 cells with pertussis toxin attenuates receptor-mediated inhibition of adenylate cyclase. The toxin acts by catalyzing the ADP-ribosylation of a 41,000-dalton substrate believed to be a part of the receptor-adenylate cyclase complex. We have found that toxin treatment of NG108-15 results in inhibition of the opiate-stimulated GTPase. The concentration of toxin required for inhibition of this GTPase was similar to that needed for both attenuation of opiate inhibition of adenylate cyclase and ADP ribosylation of the 41,000-dalton substrate. Inhibition of the opiate-induced GTPase by pertussis toxin in isolated membranes required NAD, consistent with the hypothesis that this effect of the toxin resulted from ADP ribosylation of a protein component of the system. Since the opiate-stimulated GTPase is believed to play a role in the receptor-mediated decrease in adenylate cyclase activity, inhibition of this GTPase may be an important part of the mechanism by which the toxin interferes with opiate action on adenylate cyclase. 相似文献