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1.
Murine Cytomegalovirus m02 Gene Family Protects against Natural Killer Cell-Mediated Immune Surveillance
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Sofia A. Oliveira Se-Ho Park Peter Lee Albert Bendelac Thomas E. Shenk 《Journal of virology》2002,76(2):885-894
The murine cytomegalovirus m02 gene family encodes putative type I membrane glycoproteins named m02 through m16. A subset of these genes were fused to an epitope tag and cloned into an expression vector. In transfected and murine cytomegalovirus-infected cells, m02, m04, m05, m06, m07, m09, m10, and m12 localized to cytoplasmic structures near the nucleus, whereas m08 and m13 localized to a filamentous structure surrounding the nucleus. Substitution mutants lacking the m02 gene (SMsubm02) or the entire m02 gene family (SMsubm02-16) grew like their wild-type parent in cultured cells. However, whereas SMsubm02 was as pathogenic as the wild-type virus, SMsubm02-16 was markedly less virulent. SMsubm02-16 produced less infectious virus in most organs compared to wild-type virus in BALB/c and C57BL/6J mice, but it replicated to wild-type levels in the organs of immunodeficient gamma(c)/Rag2 mice, lacking multiple cell types including natural killer cells, and in C57BL/6J mice depleted of natural killer cells. These results argue that one or more members of the m02 gene family antagonize natural killer cell-mediated immune surveillance. 相似文献
2.
Steroid metabolites in urine from neonates with 21-hydroxylase deficiency are predominantly polyhydroxylated 17-hydroxyprogesterone and androgen metabolites, and most have incompletely defined structure. This study forms part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal types of steroid metabolism.Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra, obtained with constant excitation conditions, were used together to determine the structure of the D-ring and the side chain of 20-oxo and 20-hydroxy pregnane(ene)s without oxo groups on the A-, B-, and C-ring.All possible combinations of D-ring and side chain configuration were considered. Most fragmentations could be interpreted as partial or complete D-ring cleavages with loss of the side chain, aided by comparison with spectra of deuterated derivatives and of borohydride reduced metabolites. Possible rearrangement ions are also discussed. More than 140 endogenous metabolites were characterized.GC-MS/MS was especially beneficial for characterization of compounds with 16,17-dihydroxy-20-oxo structure, interpreted as markers of intra-uterine enzyme induction. It also assisted the differentiation of 16-hydroxy-20-oxo metabolites, present in urine of non-affected neonates, from the diagnostic 17-hydroxy-20-oxosteroids and enabled the detection of 15,17-dihydroxy-20-oxo compounds in low concentrations. The presence of 17,21-dihydroxylated pregnane(ene)s despite the deficit in CYP21A2 is discussed.We conclude that GC-MS combined with GC-MS/MS allows reliable identification of the structure of the D-ring and side chain of pregnane(ene)s without prior isolation, even when in low concentrations in urine. 相似文献
3.
4.
AbstractThe Argolis Peninsula covers the north-eastern part of Peloponnisos and is surrounded by the Gulf of Argosaronic. The area hosts three species of the genus Fritillaria: F. graeca, F. rhodocanakis and F. spetsiotica. Fritillaria graeca is a Greek endemic taxon and its distribution includes Peloponnisos, C & E Sterea Ellas, C Evia and in proximity to Sterea Ellas, Salamis and Kea islands, while the stenoendemic F. rhodocanakis and F. spetsiotica are mainly found on Idra and Spetses islands respectively. The last two taxa are included in the Red Data Book of Rare and Threatened Plants of Greece, while F. rhodocanakis is also included in the IUCN Red List. Hybridization among them is a common phenomenon in the areas where they coexist, leading to an array of morphologically and karyologically intermediate forms. The current study presents the taxa’s karyomorphometric analysis for the first time and reveals hybrids’ cytological variety, including differences in marker chromosomes, polyploidy and the number of B-chromosomes. 相似文献
5.
The effects of structural analogues, excitatory amino acids and certain drugs on spontaneous and potassium-stimulated exogenous taurine and GABA release were investigated in mouse cerebral cortex slices using a superfusion system. Spontaneous efflux of both amino acids was rather slow but could be enhanced by their uptake inhibitors. Taurine efflux was facilitated by exogenous taurine, hypotaurine, -alanine and GABA, whereas GABA, nipecotic acid and homotaurine effectively enhanced GABA release. The stimulatory potency of the analogues closely corresponded to their ability to inhibit taurine and GABA uptake, respectively, indicating that these efflux processes could be mediated by the carriers operating outwards. Glutamate induced GABA release, whereas taurine efflux was potentiated by aspartate, glutamate, cysteate, homocysteate and kainate. The centrally acting drugs, including GABA agonists and antagonists, as well as the proposed taurine antagonist TAG (6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide), had no marked effects on spontaneous taurine and GABA release. Potassium ions stimulated dosedependently both taurine and GABA release from the slices, the responses of taurine being strikingly slow but sustained. Exogenous GABA and nipecotic acid accelerated the potassium-stimulated GABA release, whereas picrotoxin and bicuculline were ineffective. The potassium-stimulated taurine release was unaltered or suppressed by exogenous taurine and analogues, differing in this respect from GABA release. The apparent magnitude of the depolarization-induced GABA release is thus influenced by the function of membrane transport sites, but the same conclusion cannot be drawn with regard to taurine. Haloperidol and imipramine were able to affect the evoked release of both taurine and GABA. 相似文献
6.
Oscillations in photosynthesis are initiated and supported by imbalances in the supply of ATP and NADPH to the Calvin cycle 总被引:4,自引:0,他引:4
Agu Laisk Katharina Siebke Ulvi Gerst Hillar Eichelmann Vello Oja Ulrich Heber 《Planta》1991,185(4):554-562
Oscillations in the rate of photosynthesis of sunflower (Helianthus annuus L.) leaves were induced by subjecting leaves, whose photosynthetic apparatus had been activated, to a sudden transition from darkness or low light to high-intensity illumination, or by transfering them in the light from air to an atmosphere containing saturating CO2. It was found that at the first maximum, light-and CO2-saturated photosynthesis can be much faster than steady-state photosynthesis. Both QA in the reaction center of PS II and P700 in the reaction center of PS I of the chloroplast electron-transport chain were more oxidized during the maxima of photosynthesis than during the minima. Maxima of P700 oxidation slightly preceded maxima in photosynthesis. During a transition from low to high irradiance, the assimilatory force FA, which was calculated from ratios of dihydroxyacetone phosphate to phosphoglycerate under the assumption that the reactions catalyzed by NADP-dependent glyceraldehydephosphate dehydrogenase, phosphoglycerate kinase and triosephosphate isomerase are close to equilibrium, oscillated in parallel with photosynthesis. However, only one of its components, the calculated phosphorylation potential (ATP)/(ADP)(Pi), paralleled photosynthesis, whereas calculated NADPH/NADP ratios exhibited antiparallel behaviour. When photosynthetic oscillations were initiated by a transition from low to high CO2, the assimilatory force FA declined, was very low at the first minimum of photosynthesis and increased as photosynthesis rose to its second maximum. The observations indicate that the minima in photosynthesis are caused by lack of ATP. This leads to overreduction of the electron-transport chain which is indicated by the reduction of P700. During photosynthetic oscillations the chloroplast thylakoid system is unable to adjust the supply of ATP and NADPH rapidly to demand at the stoichiometric relationship required by the carbonreduction cycle.Abbreviations PGA
3-phosphoglycerate
- DHAP
dihydroxyacetone phosphate
- P700
electron-donor pigment in the reaction enter of PS I
- QA
quinone acceptor in the reaction center of PS II
This work received support from the Estonian Academy of Sciences, the Bavarian Ministry of Science and Art and the Sonderforschungsbereich 251 of the University of Würzburg. We are grateful for criticism by D.A. Walker, Robert Hill Institute, University of Sheffield, U.K. and by Mark Stitt, Institute of Botany, University of Heidelberg, FRG. 相似文献
7.
Michael J. Sofia William T. Jackson Davis L. SaussyJr. Steven A. Silbaugh Larry L. Froelich Sandra L. Cockerham Peter W. Stengel 《Bioorganic & medicinal chemistry letters》1992,2(12)
A series of
-alkoxyphenols containing a tetrazole acid sidechain have been prepared as antagonists of leukotriene B4 receptors. These compounds were tested as receptor antagonists of human neutrophil and guinea pig lung membrane leukotriene B4 receptors. Compounds in this series were found to be up to 18-fold more potent than LY255283. These results indicate that the acyl group of the 1,2,4,5 substituted hydroxyacetophenone class of LTB4 antagonists is not critical to antagonist potency. 相似文献
8.
Pekka Oja Raija M. T. Laukkanen T. Katriina Kukkonen-Harjula Ilkka M. Vuori Matti E. Pasanen Seppo P. T. Niittym?ki Tiina Solakivi 《European journal of applied physiology and occupational physiology》1991,62(6):400-404
Two experiments were carried out to compare the cardiorespiratory and metabolic effects of cross-country skiing and running training during two successive winters. Forty-year-old men were randomly assigned into skiing (n = 15 in study 1, n = 16 in study 2), running (n = 16 in study 1 and n = 16 in study 2) and control (n = 17 in study 1 and n = 16 in study 2) groups. Three subjects dropped out of the programme. The training lasted 9-10 weeks with 40-min exercise sessions three times each week. The training intensity was controlled at 75%-85% of the maximal oxygen consumption (VO2max) using portable heart rate metres and the mean heart rate was 156-157 beats.min-1 in the training groups. In the pooled data of the two studies the mean increase in the VO2max (in ml.min-1.kg-1) on a cycle ergometer was 17% for the skiing group, 13% for the running group and 2% for the control group. The increase in VO2max was highly significant in the combined exercise group compared to the control group but did not differ significantly between the skiing and running groups. The fasting serum concentrations of lipoproteins and insulin did not change significantly in any of the groups. These results suggested that training by cross-country skiing and running of the same duration and intensity at each session for 9-10 weeks improved equally the cardiorespiratory fitness of untrained middle-aged men. 相似文献
9.
Synthesis of the transferrin receptor by cultures of embryonic chicken spinal neurons 总被引:4,自引:1,他引:3
G J Markelonis T H Oh L P Park C Y Cha C A Sofia J W Kim P Azari 《The Journal of cell biology》1985,100(1):8-17
We have purified a glycoprotein from chicken sciatic nerves, sciatin, which has pronounced trophic effects on avian skeletal muscle cells in culture. Recent studies have shown that sciatin is identical to the iron-transport protein, transferrin, in terms of its physicochemical structure, immunological reactivity, and biological activity. To determine whether transferrin is synthesized and released by neuronal tissue, we incubated cultures of dissociated chicken spinal neurons in a medium free of L-leucine containing either L-3H-amino acids or L-[14C]leucine and immunoprecipitated transferrin with highly specific antibodies. The radiolabeled protein precipitated by rabbit heteroclonal, goat heteroclonal, or mouse monoclonal antitransferrin antibodies increased in specific activity in a linear manner for at least 30 min. Synthesis of this protein was abolished by the presence of puromycin (20 micrograms/ml) or cycloheximide (10(-5) M). The disappearance of the radiolabeled protein from cells was linear with a half-life (t 1/2) of 8-10 h. When immunoprecipitates were separated by SDS gel electrophoresis, a prominent band corresponding to transferrin (Mr 84,000) was visualized by staining with Coomassie Blue. However, when such gels were fluorographed, no radioactivity was apparent in the transferrin region of the gel although a prominent radioactive band was visualized at an Mr of 56,000. The protein of Mr 56,000 was not simply a degradation product of transferrin because this particular protein band was not generated by incubating radiolabeled transferrin with unlabeled neuronal homogenates. The protein of Mr 56,000 was purified from embryonic chicken brain and spinal cord by immunoabsorption chromatography on mouse monoclonal antitransferrin IgG conjugated to Sepharose 4B followed by affinity chromatography on immobilized transferrin. The purified protein bound radioiodinated transferrin and was precipitated by rabbit anti-chicken transferrin-receptor antibodies. Furthermore, this receptor protein was found to be localized on the plasma membrane of dorsal root ganglion neurons by immunocytochemistry using the peroxidase-antiperoxidase technique, and by blocking experiments, which showed that antitransferrin receptor IgG could inhibit the binding of fluorescein-conjugated transferrin at 4 degrees C to cultured neurons in vitro. From these data, we conclude that transferrin is not synthesized by cultures of chicken spinal cord neurons, but that the receptor for transferrin is synthesized by these cultures and is precipitated by antitransferrin antibodies as an antigen-receptor complex. 相似文献
10.
Zooplankton composition of ten reservoirs in southern Brazil 总被引:5,自引:2,他引:3
Marlene Sofia Arcifa 《Hydrobiologia》1984,113(1):137-145
The zooplankton of ten reservoirs of Sao Paulo State was analyzed as part of a larger project, Typology of Reservoirs of São Paulo State.Twenty-four genera of Rotifera, six species of Copepoda and at least nine species of Cladocera were found in samples collected on four occasions in 1979. In general, Rotifera dominated in most reservoirs, although fluctuations occurred during the year.The reservoirs were arranged in four groups, according to zooplankton density, whose range was 10 to 500 i 1–1.The average composition of Crustacea, in number of species at any one time is comparable to those of other water bodies, being a little higher than that of Colorado lakes.The number of species of limnetic Cladocera in Brazil is between those of Holarctic Region and Tropical Asia.
Ceriodaphnia cornuta and Bosminopsis deitersi, and a few species of Daphnia are typical of Brazilian zooplankton. Thermocyclops crassus is common in the southern reservoirs but T. minutus seems to be more widely distributed in Brazil. Calanoida occurred in relatively few reservoirs in São Paulo and usually one species at one time. Brachionus and Keratella were more abundant closer to the Equator then to the Tropics, where other genera seem to be more abundant.The range in size of the planktonic Crustacea is relatively small when compared to temperate lakes, being similar to that of other tropical lakes. 相似文献