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1.
Renata Dziedzic Manjot Kiran Przemyslaw Plocinski Malgorzata Ziolkiewicz Anna Brzostek Meredith Moomey Indumati S. Vadrevu Jaroslaw Dziadek Murty Madiraju Malini Rajagopalan 《PloS one》2010,5(7)
FtsZ assembly at the midcell division site in the form of a Z-ring is crucial for initiation of the cell division process in eubacteria. It is largely unknown how this process is regulated in the human pathogen Mycobacterium tuberculosis. Here we show that the expression of clpX was upregulated upon macrophage infection and exposure to cephalexin antibiotic, the conditions where FtsZ-ring assembly is delayed. Independently, we show using pull-down, solid-phase binding, bacterial two-hybrid and mycobacterial protein fragment complementation assays, that M. tuberculosis FtsZ interacts with ClpX, the substrate recognition domain of the ClpXP protease. Incubation of FtsZ with ClpX increased the critical concentration of GTP-dependent polymerization of FtsZ. Immunoblotting revealed that the intracellular ratio of ClpX to FtsZ in wild type M. tuberculosis is approximately 1∶2. Overproduction of ClpX increased cell length and modulated the localization of FtsZ at midcell sites; however, intracellular FtsZ levels were unaffected. A ClpX-CFP fusion protein localized to the cell poles and midcell sites and colocalized with the FtsZ-YFP protein. ClpX also interacted with FtsZ mutant proteins defective for binding to and hydrolyzing GTP and possibly for interactions with other proteins. Taken together, our results suggest that M. tuberculosis ClpX interacts stoichiometrically with FtsZ protomers, independent of its nucleotide-bound state and negatively regulates FtsZ activities, hence cell division. 相似文献
2.
A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY 总被引:4,自引:0,他引:4
Ken McElreavey Raphaël Rappaport Eric Vilain Nacer Abbas François Richaud Stéphen Lortat-Jacob Roland Berger Maryvonne LeConiat Chafika Boucekkine Kiran Kucheria Samia Temtamy Claire Nihoul-Fekete Raja Brauner Marc Fellous 《Human genetics》1992,90(1-2):121-125
Summary A total of 30 cases of 46,XX true hermaphroditism was analysed for Y-DNA sequences including the recently cloned gene for male testis-determination SRY. In 3 cases, a portion of the Y chromosome including SRY was present and, in 2 cases, was localised, to Xp22 by in situ hybridisation. Since previous studies have shown that the majority of XX males are generated by an X-Y chromosomal interchange, the Xp22 position of the Yp material suggests that certain cases of hermaphroditism can arise by the same meiotic event. The phenotype in the 3 SRY-positive cases may be caused by X-inactivation resulting in somatic mosaicism of testis-determining factor expression giving rise to both testicular and ovarian tissues. Autosomal or X-linked mutation(s) elsewhere in the sex-determining pathway may explain the phenotype observed in the remaining 27 SRY-negative cases. 相似文献
3.
Anil K. Sinha V. Ann Linscombe B. Bhaskar Gollapudi George C. Jersey Colin N. Park 《Cell biology and toxicology》1985,1(4):333-342
Sister chromatid exchanges (SCE) were analyzed in peripheral blood lymphocytes from a select group of 71 healthy men, 56 nonsmokers and 15 cigarette smokers. In addition to estimating baseline SCE, data were examined to seek relationships of SCE frequencies to age and smoking. The baseline value of 7.53 SCE per cell from the 56 nonsmokers was within the range (5.60 to 9.10 SCE/cell) reported for other human populations. No relationship was found between the mean SCE frequency per cell and age. However, a significant increase in the SCE mean value was observed in smokers as compared to nonsmokers. The results of this study are compared with those of other reports on SCE effects of age and smoking.Abbreviations BUdR
5-bromo,2-deoxyuridine
- SCE
sister chromatid exchange 相似文献
4.
The effects of lead on Ca2+ homeostasis in nerve terminals was studied. Incubation with leadin vitro stimulated the activity of calmodulin and the maximum effect was observed at 30 M lead, higher concentrations had an inhibitory effect.In vivo exposure to lead increased the activity of calmodulin by 45%. Lead had an inhibitory effect on Ca2+ ATPase activity in both calmodulin-rich and calmodulin-depleted synaptic plasma membranes, the IC50 values for inhibition being 13.34 and 16.69 M respectively. Exogenous addition of calmodulin (5 g) and glutathione (1 mM) to calmodulin rich synaptic plasma membranes reversed the inhibition by IC50 concentration of lead.In vivo exposure of lead also significantly reduced the Ca2+ ATPase activity, resulting in an increase in intrasynaptosomal calcium. Concomitant with the increase in intrasynaptosomal calcium, lipid peroxidation values also increased significantly in lead-treated animals. In addition lead also had an inhibitory effect on depolarization induced Ca2+ uptake and the inhibition was found to be a competitive one. The results sugest that lead exerts its toxic effects by modifications of the intracellular calcium messenger system which would have serious consequences on neuronal functioning. 相似文献
5.
RasG protein accumulation occurs just prior to amoebae emergence during spore germination in Dictyostelium discoideum 总被引:1,自引:0,他引:1
Meenal Khosla George B. Spiegelman Gerald Weeks Todd W. Sands Kiran J. Virdy David A. Cotter 《FEMS microbiology letters》1994,117(3):293-298
Abstract RasG protein levels in dormant and germinating spores of Dictyostelium discoideum strains JC1 and SG1 were estimated by Western blotting. Ras Glevels were very low in dormant spores and remained low during the lag period, regardless of whether spores were heat activated or treated with autoactivator during the early stages of spore germination. RasG levels increased late during spore swelling just prior to the emergence stage of germination. These data are consistent with a requirement for RasG during vegetative growth. 相似文献
6.
Blood serum total cholesterol levels of crossbred Taur-indicus donor cows (n=22), in their 1st to 4th parity, were studied as an indicator of embryo yield. These cows were superovulated either with FSH or PMSG + anti-PMSG on the 12th day of the synchronized estrous cycle. The total and transferable number of embryos did not differ significantly between the treatment groups. The number of corpora lutea and total and transferable embryos in donors having total cholesterol levels <140 mg/dl were significantly (P < 0.05) lower than those of cows having >140 mg/dl, indicating that low total cholesterol levels might adversely affect superovulatory response. Thus, estimation of total cholesterol concentrations of potential donors can be a useful tool for predicting superovulatory responses. 相似文献
7.
Piotr Berman Paul Bertone Bhaskar Dasgupta Mark Gerstein Ming-Yang Kao Michael Snyder 《Journal of computational biology》2004,11(4):766-785
In this paper, we consider several variations of the following basic tiling problem: given a sequence of real numbers with two size-bound parameters, we want to find a set of tiles of maximum total weight such that each tiles satisfies the size bounds. A solution to this problem is important to a number of computational biology applications such as selecting genomic DNA fragments for PCR-based amplicon microarrays and performing homology searches with long sequence queries. Our goal is to design efficient algorithms with linear or near-linear time and space in the normal range of parameter values for these problems. For this purpose, we first discuss the solution to a basic online interval maximum problem via a sliding-window approach and show how to use this solution in a nontrivial manner for many of the tiling problems introduced. We also discuss NP-hardness results and approximation algorithms for generalizing our basic tiling problem to higher dimensions. Finally, computational results from applying our tiling algorithms to genomic sequences of five model eukaryotes are reported. 相似文献
8.
Genetics of high level penicillin resistance in clinical isolates of Streptococcus pneumoniae 总被引:5,自引:0,他引:5
Victoria A Barcus Kiran Ghanekar Maggie Yeo Tracey J Coffey Christopher G Dowson 《FEMS microbiology letters》1995,126(3):299-303
Abstract Mosaic penicillin-binding proteins (PBP) 1A, 2X and 2B genes were cloned from four clinical isolates of Streptococcus pneumoniae with levels of susceptibility to penicillin ranging from 1.5 to 16 μg benzylpenicillin ml−1 . In each instance it was possible to transform either the penicillin-sensitive laboratory strain R6 or a sensitive clinical isolate 110K/70 to the full level of penicillin resistance with these three penicillin-binding proteins alone. Until now it has not been possible to clearly determine whether alterations to PBP1A, 2X and 2B alone were sufficient to attain high level penicillin resistance. 相似文献
9.
Neurochemical changes in the extracellular fluid of the rostral ventrolateral medulla (RVLM) were produced by changes in arterial blood pressure. Blood pressure was raised or lowered with systemic infusions of phenylephrine or nitroprusside and neurochemicals were recovered from RVLM by in vivo microdialysis. A dialysis probe 300 microns in diameter and 500 microns in length was stereotaxically implanted in the RVLM of the urethane-anesthetized rat. Sterile physiological Ringer's solution was perfused at a rate of 1.5 microliter/min. The perfusate was collected under ice-cold conditions every 15 min for the assay of epinephrine, dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), ascorbic acid, and uric acid. After stable baseline neurochemical concentrations were achieved, animals were infused with phenylephrine or nitroprusside intravenously to raise or lower the blood pressure. Increasing blood pressure 50 mm Hg above the baseline value by phenylephrine led to a significant reduction in heart rate and a reduction in extracellular epinephrine and DOPAC concentrations. The 5-HIAA concentration was increased during the hypertensive drug infusion. There were no changes in the concentrations of ascorbic acid or uric acid. Hypotension produced by nitroprusside (-20 mm Hg) led to neurochemical changes which were the reciprocal of those seen during hypertension. During hypotension, heart rate increased as did the extracellular fluid epinephrine concentration. The 5-HIAA concentration fell with hypotension and remained depressed following the nitroprusside infusion. Ascorbic acid and uric acid concentrations did not change during hypotension but ascorbic acid did increase after the nitroprusside infusion stopped. These data provide direct evidence that epinephrine release in RVLM is linked to changes in systemic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.
Songbirds show dramatic neural plasticity as adults, including large-scale anatomical changes in discrete brain regions ("song control nuclei") controlling the production of singing behavior. The volumes of several song control nuclei are much larger in the breeding season than in the nonbreeding season, and these seasonal neural changes are regulated by plasma testosterone (T) levels. In many cases, the effects of T on the central nervous system are mediated by neural conversion to estradiol (E(2)) by the enzyme aromatase. The forebrain of male songbirds expresses very high levels of aromatase, in some cases adjacent to song control nuclei. We examined the effects of aromatase inhibition and estrogen treatment on song nuclei size using wild male songbirds in both the breeding and nonbreeding seasons. In breeding males, aromatase inhibition caused the volume of a telencephalic song control nucleus (HVC) to decrease, and this effect was partially rescued by concurrent estrogen replacement. In nonbreeding males, estradiol treatment caused HVC to grow to maximal spring size within 2 weeks. Overall, these data suggest that aromatization of T is an important mediator of song control system plasticity, and that estradiol has neurotrophic effects in adult male songbirds. This study demonstrates that estrogen can affect adult neural plasticity on a gross anatomical scale and is the first examination of estrogen effects on the brain of a wild animal. 相似文献