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排序方式: 共有273条查询结果,搜索用时 93 毫秒
41.
Antonio Rodríguez-García Alberto Sola-Landa Kristian Apel Fernando Santos-Beneit Juan F. Martín 《Nucleic acids research》2009,37(10):3230-3242
Bacterial growth requires equilibrated concentration of C, N and P sources. This work shows a phosphate control over the nitrogen metabolism in the model actinomycete Streptomyces coelicolor. Phosphate control of metabolism in Streptomyces is exerted by the two component system PhoR-PhoP. The response regulator PhoP binds to well-known PHO boxes composed of direct repeat units (DRus). PhoP binds to the glnR promoter, encoding the major nitrogen regulator as shown by EMSA studies, but not to the glnRII promoter under identical experimental conditions. PhoP also binds to the promoters of glnA and glnII encoding two glutamine synthetases, and to the promoter of the amtB-glnK-glnD operon, encoding an ammonium transporter and two putative nitrogen sensing/regulatory proteins. Footprinting analyses revealed that the PhoP-binding sequence overlaps the GlnR boxes in both glnA and glnII. ‘Information theory’ quantitative analyses of base conservation allowed us to establish the structure of the PhoP-binding regions in the glnR, glnA, glnII and amtB genes. Expression studies using luxAB as reporter showed that PhoP represses the above mentioned nitrogen metabolism genes. A mutant deleted in PhoP showed increased expression of the nitrogen metabolism genes. The possible conservation of phosphate control over nitrogen metabolism in other microorganisms is discussed. 相似文献
42.
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44.
Neuromodulin (P-57, GAP-43, B-50, F-1) is a neurospecific calmodulin binding protein that is phosphorylated by protein kinase C. Phosphorylation by protein kinase C has been shown to abolish the affinity of neuromodulin for calmodulin [Alexander, K. A., Cimler, B. M., Meier, K. E., & Storm, D. R. (1987) J. Biol. Chem. 262, 6108-6113], and we have proposed that the concentration of free CaM in neurons may be regulated by phosphorylation and dephosphorylation of neuromodulin. The purpose of this study was to identify the protein kinase C phosphorylation site(s) in neuromodulin using recombinant neuromodulin as a substrate. Toward this end, it was demonstrated that recombinant neuromodulin purified from Escherichia coli and bovine neuromodulin were phosphorylated with similar Km values and stoichiometries and that protein kinase C mediated phosphorylation of both proteins abolished binding to calmodulin-Sepharose. Recombinant neuromodulin was phosphorylated by using protein kinase C and [gamma-32P]ATP and digested with trypsin, and the resulting peptides were separated by HPLC. Only one 32P-labeled tryptic peptide was generated from phosphorylated neuromodulin. The sequence of this peptide was IQASFR. The serine in this peptide corresponds to position 41 of the entire protein, which is adjacent to or contained within the calmodulin binding domain of neuromodulin. A synthetic peptide, QASFRGHITRKKLKGEK, corresponding to the calmodulin binding domain with a few flanking residues, including serine-41, was also phosphorylated by protein kinase C. We conclude that serine-41 is the protein kinase C phosphorylation site of neuromodulin and that phosphorylation of this amino acid residue blocks binding of calmodulin to neuromodulin.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
45.
Changes in gibberellin-like activity and content of indole type auxins were investigated during grain development of the two high-lysine barley (Hordeum vulgare L.) genotypes Sv 73608 and Risø 1508, and their corresponding normal cultivars Mona and Bomi. A peak in gibberellin-like activity was found in developing grains of the normal cultivars about 18 days after anthesis, whereas the grains of the high-lysine genotypes showed a two to five times higher maximum about 3–4 days later. The auxin content of the cultivar Bomi showed a maximum between the 22nd and the 29th day after anthesis, whereas, throughout their development the grains of the mutant Risø 1508 exhibited only about 1/10 of the maximum level of auxin found in the grains of Bomi. The normal cultivar Mona also displayed higher contents of auxin than the high-lysine genotypes Sv 73608, particularly at the later stages of grain growth, but the differences in concentration were considerable smaller than for the pair ‘Bomi’—‘Risø 1508’. It is suggested that auxins play an important role in the development of barley grains. 相似文献
46.
Marí C. Santos Krissie D. Soares Betina M. Beltrame Natally S. B. Toson Maria do Carmo B. Pimentel Sérgio A. L. Bordignon Miriam A. Apel Andreas S. L. Mendez Amélia T. Henriques 《化学与生物多样性》2021,18(7):e2100041
The present study investigates the chemical composition, anti-inflammatory, and antihypertensive activities, in vitro, from extracts of Cuphea lindmaniana and Cuphea urbaniana leaves. The extraction was performed ultrasound-assisted, and UHPLC/MS analysis was in positive mode ionization. The anti-inflammatory activity of the extracts and miquelianin were assayed at concentrations 0.001–10 μg/mL by chemotaxis on rat polymorphonuclear neutrophils. The antihypertensive activity was performed by angiotensin-converting enzyme (ACE) inhibition. From the nineteen proposed compounds, six of them are described for the first time in this genus. The extracts displayed antichemotactic effect with a reduction of 100 % of the neutrophil migration, in vitro, in most concentrations. The ACE-inhibition presented results ranging from 19.58 to 22.82 %. In conclusion, C. lindmaniana and C. urbaniana extracts contain a rich diversity of flavonoids and display in vitro anti-inflammatory and antihypertensive potential. Thus, this study could serve as a scientific baseline for further investigation, on developmental novel products with therapeutic actions. 相似文献
47.
Daniel Apel Michele Brunelli Mohammed El-Gahry J. Christoph Geller Bernward Lauer Marc-Alexander Ohlow 《Indian pacing and electrophysiology journal》2018,18(5):159-164
Aims
The aim of this study was to analyze whether local application of 3% hydrogen peroxide (H2O2) additionally to standard antibiotic prophylaxis following implantation of cardiac implantable electronic devices (CIED) reduces the incidence of pocket infections (PI).Methods
In this observational case-control study every patient from the group additionally treated with H2O2 was matched with two patients out of the control group for age, male-gender, body-mass-index and operation time. The incidence of PI within 365 days after device implantation was compared.Results
During the 5-year study period, 429 consecutive patients were additionally treated with H2O2 and matched with 858 patients undergoing standard treatment (mean age 69?±?12 years, 876 males (67.4%), body-mass-index 28?±?4.0?kg/m2 and operation time 45?±?23?min). Except for a more frequent use of dual-platelet-inhibition in the H2O2-group, clinical characteristics were otherwise similar. A total of 23 (1.78%) PIs occurred, most of them (14/23; 61%) during the first 45 days after implantation procedure. The use of H2O2 was associated with a significant reduction (3/429?=?0.69% versus 20/858?=?2.33%; p?=?0.04), although patients of the H2O2 treated group received more complex procedures increasing the risk of PI.Conclusion
Intraoperative local application of 3% H2O2 seems to be associated with a significant reduced incidence of PI following implantation of CIED. Because of its non-randomized character this trial should be considered as a hypothesis generating study. 相似文献48.
Sönke Runge Barbara van Cleve Nikolai Lebedev Gregory Armstrong Klaus Apel 《Planta》1995,197(3):490-500
Mutant lines of Arabidopsis thaliana that are either blocked at various steps of the biosynthetic pathway of chlorophyll (Chl) or that are disturbed in one of the subsequent steps leading to the assembly of an active photosynthetic membrane were isolated by screening for Chl-deficient xantha (xan) mutants. Only mutants that segregated in a 31 ratio, that contained the same carotenoid spectrum as etiolated wild-type seedlings and less than 2% of the Chl of wild-type control seedlings, and whose Chl content was not affected by the addition of sucrose to the growth medium were selected for a more detailed analysis. As a final test for the classification of the selected mutants, light-grown xan mutants were vacuum-infiltrated and incubated with the common precursor of tetrapyrroles, -aminolevulinic acid (ALA), in the dark. Two major groups of mutants could be distinguished. Some of the mutants were blocked at various steps of the Chl pathway between ALA and protochlorophyllide (Pchlide) and did not accumulate the latter in the dark. The other mutants accumulated Pchlide in the dark regardless of whether exogenous ALA was added. This latter group could be subdivided into mutants with a biochemical lesion in a recently discovered second light-dependent Pchlide reduction step that occurs in green plants and mutants that have blocks in the assembly of Chl protein complexes. In the present work a total of seven different loci could be defined genetically in Arabidopsis that affect the synthesis of Chl and its integration into the growing photosynthetic membrane.Abbreviations ALA
-aminolevulinic acid
- Chl
chlorophyll
- Chlide
chlorophyllide
- Pchlide
protochlorophyllide
- POR
NADPH-Protochlorophyllide oxidoreductase
-
xan
xantha
This study was initiated while one of the authors (K.A.) was on sabbatical leave in the laboratory of Dr. C. Somerville (MSU, East Lansing, Mich., USA). We are extremely grateful to Dr. Somerville and his coworkers for advice and support during this time. This research was supported by the Deutsche Forschungsgemeinschaft and the Schweizerischer Nationalfonds. 相似文献
49.
The CO2 compensation concentration (Γ) and leaf anatomy were determined in 107 species of six tribes of Brassicaceae. There was an abundant bundle-sheath in all investigated species. The Moricandia syndrome, characterized by a high concentration of chloroplasts in the bundle-sheath cells and Γ values < 30 cm3(CO2) m-3, was found within species of the genera Moricandia, Diplotaxis and Brassica. Available results from molecular systematics indicate a common phylogenetic ancestor, suggesting monophyletic evolution
of the syndrome within the tribe Brassiceae. Nevertheless, Γ values of about 30 cm3 m-3 in some other genera of the tribes
Brassiceae and Sisymbrieae indicate an evolutionarily sliding, gradual transition from C3 ancestors.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
50.
Distinct roles for light-dependent NADPH:protochlorophyllide oxidoreductases (POR) A and B during greening in higher plants 总被引:5,自引:2,他引:3
Sönke Runge Ulrich Sperling Geneviève Frick Klaus Apel Gregory A. Armstrong 《The Plant journal : for cell and molecular biology》1996,9(4):513-523
Light-dependent NADPH:protochlorophyllide oxidoreductase (POR), a nuclear-encoded plastid-localized enzyme, catalyzes the photoreduction of protochlorophyllide (Pchlide) to chlorophyllide in higher plants, algae and cyanobacteria. Angiosperms require light for chlorophyll (Chl) biosynthesis and have recently been shown to contain two POR-encoding genes, PorA and PorB , that are differentially regulated by light and developmental state. PorA expression rapidly becomes undetectable after illumination of etiolated seedlings, whereas PorB expression persists throughout greening and in adult plants. In order to study the in vivo functions of Arabidopsis POR A and POR B we have abolished the expression of PorA through the use of the phytochrome A-mediated far-red high irradiance response. Wild-type seedlings grown in continuous far-red light (cFR) display the morphology of white light (WL)-grown seedlings, but contain only traces of Chl and do not green upon transfer to WL. This cFR-induced greening defect correlates with the absence of PorA mRNA, the putative POR A protein, phototransformable Pchlide-F655 , and with strongly reduced POR enzymatic activity in plant extracts. In contrast, a cFR-grown phyA mutant expresses the PorA gene, accumulates Chl and visibly greens in WL. Furthermore, constitutive overexpression of POR A in cFR-grown transgenic Arabidopsis wild-type seedlings restores Chl accumulation and WL-induced greening. These data demonstrate that POR A is required for greening and that the availability of POR A limits Chl accumulation during growth in cFR. POR B apparently provides a means to sustain light-dependent Chl biosynthesis in fully greened, mature plants in the absence of phototransformable Pchlide-F655 . 相似文献