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991.
Summary Pituitaries of male and female rats neonatally treated with oestradiol dipropionate were examined with light and electron microscopy, disc electrophoresis and in vitro C14-leucine incorporation.Single dose of oestradiol administered shortly after birth to male rats has an prolonged stimulative effect on LTH synthesis and release. This is expressed in the cell hypertrophy, proliferation of ER, increase of corresponding band density and higher rate of 14C-leucine incorporation. In females this effect was less pronounced.STH cell in the treated male pituitaries were degranulated, corresponding hormone band density significantly lowered and incorporation of 14C-leucine was reduced. This could be considered as an inhibitory effect of oestradiol on STH synthesis and release. Such effect was more expressed two than four months after treatment and is more pronounced in male than in female rats.The technical assistence of Slobodanka Selimovi is gratefully acknowledged. 相似文献
992.
Development of a nuclear polyhedrosis in cells of Rhynchosciara angelae (Diptera, Sciaridae) and patterns of DNA synthesis in the infected cells 总被引:1,自引:0,他引:1
J S Morgante A B Da Cunha C Pavan J J Biesele R W Riess M C Garrido 《Journal of invertebrate pathology》1974,24(1):93-105
An ultrastructural and autoradiographic study of the infection of cells of Rhynchosciara angelae by a nuclear polyhedrosis virus (RPV) is presented. RPV is a DNA virus and causes a dramatic increase in the volume of the infected cells and in the sizes of chromosomes and their DNA contents. The structure of the nucleoli changes with the infection and the changes are mainly related to an increase of DNA synthesis. The concentration of ribosomes increases in the cytoplasm of the infected cells. Autoradiographic study of the DNA synthesis showed that it varies with the infective process.Four patterns of DNA synthesis, in relation to the host chromosomes and the virus, were disclosed by means of tritiated thymidine incorporation in the infected nuclei. The patterns are: (1) incorporation mainly in the chromosomes, (2) incorporation in the chromosomes and in the nucleoplasm, (3) incorporation only in the nucleoplasm, and (4) incorporation mainly in the chromosomes in dissociation. There is indication of a succession 1→2 and 3→4. The succession of patterns indicates that the virus induces first the increase of synthesis of host cell DNA and RNA. The bulk of the synthesis of viral DNA is evident only after the host cell DNA and RNA machinery is amplified. The aspects of the formation of viral membrane indicate that it is a de novo process in which the membrane material is capable of self-assembly. 相似文献
993.
Vladimir Bezjak 《Antonie van Leeuwenhoek》1954,20(1):269-272
Summary The purpose of this study was to find out whether there existed any difference betweenC. diphtheriae typemitis always present in the nasal cavity of ozaena patients (the so-calledC. belfanti) andC. diphtheriae of themitis type found in diphtheria patients or carriers.
Studying in details all the morphological, cultural and biochemical properties, a difference was found to exist in the reduction
of nitrates. This test was investigated in 55 strains ofC. belfanti and 45 strains of themitis type ofC. diphtheriae. All the strains ofC. belfanti yielded negative results in the reduction of nitrates, while all strains ofC. diphtheriae typemitis reduced nitrates within 24 hours.
The value of this observation was shorty discussed. 相似文献
994.
Transformation of three-component redox pattern of cytochrome (Cyt) b559 in PS II membrane fragments upon various treatments is manifested in decrease of the relative content (R) of the high potential (HP) redox form of Cyt b559 and concomitant increase in the fractions of the two lower potential forms. Redox titration of Cyt b559 in different types of PS II membrane preparations was performed and revealed that (1) alteration of redox titration curve of Cyt b559 upon treatment of a sample is not specific to the type of treatment; (2) each value of RHP defines the individual shape of the redox titration curve; (3) population of Cyt b559 may exist in several stable forms with multicomponent redox pattern: three types of three-component redox pattern and one type of two-component redox pattern as well as in the form with a single Em; (4) transformation of Cyt b559 proceeds as successive conversion between the stable forms with multicomponent redox pattern; (5) upon harsh treatments, Cyt b559 abruptly converts into the state with a single Em which value is intermediate between the Em values of the two lower potential forms. Analysis of the data using the model of Cyt b559-quinone redox interaction revealed that diminution of RHP in a range from 80 to 10% reflects a shift in redox equilibrium between the heme group of Cyt b559 and the interacting quinone, due to a gradual decrease of 90?mV in Em of the heme group at the virtually unchanged Em of the quinone component. 相似文献
995.
996.
Arifa Sosan Dimitri Svistunenko Darya Straltsova Katsiaryna Tsiurkina Igor Smolich Tracy Lawson Sunitha Subramaniam Vladimir Golovko David Anderson Anatoliy Sokolik Ian Colbeck Vadim Demidchik 《The Plant journal : for cell and molecular biology》2016,85(2):245-257
Silver nanoparticles (Ag NPs) are the world's most important nanomaterial and nanotoxicant. The aim of this study was to determine the early stages of interactions between Ag NPs and plant cells, and to investigate their physiological roles. We have shown that the addition of Ag NPs to cultivation medium, at levels above 300 mg L?1, inhibited Arabidopsis thaliana root elongation and leaf expansion. This also resulted in decreased photosynthetic efficiency and the extreme accumulation of Ag in tissues. Acute application of Ag NPs induced a transient elevation of [Ca2+]cyt and the accumulation of reactive oxygen species (ROS; partially generated by NADPH oxidase). Whole‐cell patch‐clamp measurements on root cell protoplasts demonstrated that Ag NPs slightly inhibited plasma membrane K+ efflux and Ca2+ influx currents, or caused membrane breakdown; however, in excised outside‐out patches, Ag NPs activated Gd3+‐sensitive Ca2+ influx channels with unitary conductance of approximately 56 pS. Bulk particles did not modify the plasma membrane currents. Tests with electron paramagnetic resonance spectroscopy showed that Ag NPs were not able to catalyse hydroxyl radical generation, but that they directly oxidized the major plant antioxidant, l ‐ascorbic acid. Overall, the data presented shed light on mechanisms of the impact of nanosilver on plant cells, and show that these include the induction of classical stress signalling reactions (mediated by [Ca2+]cyt and ROS) and a specific effect on the plasma membrane conductance and the reduced ascorbate. 相似文献
997.
Biochemical characterization of two haloalkane dehalogenases: DccA from Caulobacter crescentus and DsaA from Saccharomonospora azurea
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Vladimir N. Malashkevich Steven C. Almo Emily C. Mundorff 《Protein science : a publication of the Protein Society》2016,25(4):877-886
Two putative haloalkane dehalogenases (HLDs) of the HLD‐I subfamily, DccA from Caulobacter crescentus and DsaA from Saccharomonospora azurea, have been identified based on sequence comparisons with functionally characterized HLD enzymes. The two genes were synthesized, functionally expressed in E. coli and shown to have activity toward a panel of haloalkane substrates. DsaA has a moderate activity level and a preference for long (greater than 3 carbons) brominated substrates, but little activity toward chlorinated alkanes. DccA shows high activity with both long brominated and chlorinated alkanes. The structure of DccA was determined by X‐ray crystallography and was refined to 1.5 Å resolution. The enzyme has a large and open binding pocket with two well‐defined access tunnels. A structural alignment of HLD‐I subfamily members suggests a possible basis for substrate specificity is due to access tunnel size. 相似文献
998.
999.
Vyacheslav?A.?Shmarov Vladimir?V.?Malashchenko Maksim?E.?Meniailo Natalia?D.?Gazatova Natalia?M.?Todosenko Olga?B.?Melashchenko Andrei?G.?Goncharov Victor?I.?SeledtsovEmail author 《European cytokine network》2016,27(4):102-107
CD3+ T lymphocytes were isolated by positive magnetic separation from the peripheral blood of healthy donors. In the absence of any additional activating stimuli, interleukin-7 (IL-7) was shown to augment the levels of T cells expressing CD25 activation marker both in CD4-positive and in CD4-negative effector memory (CD45RA-CD197-) T cell subsets, as well as in terminally differentiated (CD45RA+CD197-) T cells, without significantly affecting the activation status of naive (CD45RA+CD197+) and central memory (CD45RA-CD197+) T cells. In addition, IL-7 noticeably enhanced the production of IL-2, interferon-γ (IFN-γ), and IL-10, but not IL-4, in T cells. The direct effects of IL-7 on T cell activation induced in vitro by MACSiBead? particles coated with CD2, CD3, and CD28 antibodies (Abs) were also investigated. Upon cell activation, IL-7 significantly augmented the levels of CD25+ T cells in naive (CD45RA+CD197+), central memory (CD45RA-CD197+), and effector memory (CD45RA-CD197-) T-cell compartments. In addition, IL-7 facilitated activation of CD4- (but not CD4+) terminally differentiated effector (CD45RA+CD197-) T cells. Finally, IL-7 was found to upregulate the production of IL-2, IFN-γ, IL-4, and IL-10 by activated T cells. In conclusion, we speculate that IL-7 is capable of enhancing functional T cell activity without causing significant functional inbalance between various T cell subsets. 相似文献
1000.
Assessment of brain metabolite correlates of adeno‐associated virus‐mediated over‐expression of human alpha‐synuclein in cortical neurons by in vivo 1H‐MR spectroscopy at 9.4 T
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