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1.
Nico K. Goosen Anja M. C. Horemans Silvia J. W. Hillebrand Claudius K. Stumm Godfried D. Vogels 《Archives of microbiology》1988,150(2):165-170
The sapropelic ciliate Plagiopyla nasuta was isolated and cultured in monoculture. Optimal conditions for growth were: 15–20°C, pH about 7, and about 2% of oxygen in the headspace. Cultures of P. nasuta produced methane. Epifluorescence microscopy revealed the presence of methanogenic bacteria as endosymbionts. An endosymbiont of the ciliate was isolated and identified as Methanobacterium formicicum. In the ciliate cell these methanogens were found to be closely associated with microbody-like organelles. No mitochondria could be detected. 相似文献
2.
Huub J. M. Op den Camp Claudius K. Stumm Gerben Straatsma Piet J. L. Derikx Leo J. L. D. van Griensven 《Microbial ecology》1990,19(3):303-309
The interaction betweenAgaricus bisporus andScytalidium thermophilum on agar media was studied by differential interference contrast and phase contrast microscopy.A. bisporus combatively replacesS. thermophilum in culture on agar media. The antagonistic effect ofA. bisporus is transmissible through a cellophane membrane and causes irreversible disintegration ofS. thermophilum protoplasm, resulting in a total loss of viability after prolonged interaction between the two fungi. On compost extract agar, but not on other media, the growth rate ofA. bisporus increased from 2.7 to 5.3 mm·d–1 following contact withS. thermophilum mycelium. 相似文献
3.
A general procedure, involving 4-dimethylaminopyridine-catalysed acylation of the amino groups in the appropriate S-blocked glutathione, is reported for the preparation of N-blocked derivatives of glutathiones. 相似文献
4.
The NreB–NreC two-component system of Staphylococcus carnosus for O2 sensing cooperates with the accessory nitrate sensor NreA in the NreA–NreB–NreC system for coordinated sensing and regulation of nitrate respiration by O2 and nitrate. ApoNreA (NreA in the absence of nitrate) interacts with NreB and inhibits NreB autophosphorylation (and activation). NreB contains the phosphatase motif DxxxQ. The present study shows that NreB on its own was inactive for the dephosphorylation of the phosphorylated response regulator NreC (NreC-P), but co-incubation with NreB and NreA stimulated NreC-P dephosphorylation. Either the presence of instead of apoNreA or mutation of the phosphatase motif (D160 or Q164) of NreB abrogated phosphatase activity of NreB. Phosphatase activity was observed for anoxic (active) NreB as well as oxic NreB, therefore the functional state of NreB is not relevant for phosphatase activity. Thus, NreB is a bifunctional sensor kinase with an integral cryptic phosphatase activity. Activation of phosphatase activity and dephosphorylation of NreC-P requires NreA as a cofactor. Accordingly, NreA and nitrate have major and dual roles in NreA–NreB–NreC regulation by (i) inhibiting NreB phosphorylation and (ii) triggering a kinase/phosphatase switch of NreB when present as apoNreA. 相似文献
5.
Vincent P. Alibu Sylvie Daunes Claudius D’Silva 《Bioorganic & medicinal chemistry letters》2013,23(15):4351-4353
A series of glutathione derivatives 1–4, modified at the N,S and/or COOH sites, with in vitro antitrypanosomal activity were tested against bloodstream form Trypanosoma brucei 247 wild type and a T. b. brucei 247 strain over-expressing the multiple drug resistance protein (MRPA) by 50–100x to assess the susceptibility of these compounds to resistance by the TbMRP protein. Of the compounds tested, only compound 1 inhibited both bloodstream form T. brucei and T. bruceiMRPA, with a resistance factor of 1.4, indicating it to be an inhibitor of this protein and proteins acting in synergy with the transporter, whilst 2 & 3 and its derivatives showed reduced inhibitory activity against T. bruceiMRPA, indicating them to be substrates and susceptible to resistance. 相似文献
6.
Early Weight Loss with Liraglutide 3.0 mg Predicts 1‐Year Weight Loss and is Associated with Improvements in Clinical Markers
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7.
ADP-ribosylation is involved in a variety of biological processes, many of which are chromatin-dependent and linked to important functions during the cell cycle. However, any study on ADP-ribosylation and the cell cycle faces the problem that synchronization with chemical agents or by serum starvation and subsequent growth factor addition already activates ADP-ribosylation by itself. Here, we investigated the functional contribution of ARTD1 in cell cycle re-entry and G1/S cell cycle progression using T24 urinary bladder carcinoma cells, which synchronously re-enter the cell cycle after splitting without any additional stimuli. In synchronized cells, ARTD1 knockdown, but not inhibition of its enzymatic activity, caused specific down-regulation of cyclin E during cell cycle re-entry and G1/S progression through alterations of the chromatin composition and histone acetylation, but not of other E2F-1 target genes. Although Cdk2 formed a functional complex with the residual cyclin E, p27Kip1 protein levels increased in G1 upon ARTD1 knockdown most likely due to inappropriate cyclin E-Cdk2-induced phosphorylation-dependent degradation, leading to decelerated G1/S progression. These results provide evidence that ARTD1 regulates cell cycle re-entry and G1/S progression via cyclin E expression and p27Kip1 stability independently of its enzymatic activity, uncovering a novel cell cycle regulatory mechanism. 相似文献
8.
9.
Lammich S Okochi M Takeda M Kaether C Capell A Zimmer AK Edbauer D Walter J Steiner H Haass C 《The Journal of biological chemistry》2002,277(47):44754-44759
Alzheimer's disease (AD)-associated gamma-secretase is a presenilin (PS)- dependent proteolytic activity involved in the intramembraneous cleavage of the beta-amyloid precursor protein, Notch, LDL receptor-related protein, E-cadherin, and ErbB-4. This cut produces the corresponding intracellular domains (ICD), which are required for nuclear signaling of Notch and probably ErbB-4, the beta-amyloid precursor protein, E-cadherin, and the LDL receptor-related protein as well. We have now investigated CD44, a cell surface adhesion molecule, which also undergoes an intramembraneous cleavage to liberate its ICD. We demonstrate that this cleavage requires a PS-dependent gamma-secretase activity. A loss-of-function PS1 mutation, a PS1/PS2 knockout, as well as two independent and highly specific gamma-secretase inhibitors, abolish this cleavage. Surprisingly, small peptides similar to the amyloid beta-peptide (Abeta) are generated by an additional cut in the middle of the transmembrane region of CD44. Like Abeta, these CD44 beta-peptides are generated in a PS-dependent manner. These findings therefore suggest a dual intramembraneous cleavage mechanism mediated by PS proteins. The dual cleavage mechanism is required for nuclear signaling as well as removal of remaining transmembrane domains, a general function of PS in membrane protein metabolism. 相似文献
10.