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31.
Revital Katznelson 《FEMS microbiology letters》1989,62(4):231-242
Abstract Cyanobacterial mats, which develop on the surface of groundwater recharge basins in the Dan Region Wastewater Reclamation Project in Israel, tend to reduce the rate of effluent infiltration into the ground. The purpose of this work was to study the cyanobacterial populations found in the basins and to elucidate their contribution to the clogging process.
Three cyanobacterial types were isolated and their clogging capacity was determined in a simulation system. Simulation experiments were also used to study the effects of various flooding regimes on mat development and permeability.
In the recharge basins, clogging events have occurred in the autumn, winter or spring. During these seasons, Phormidium autumnale was found to be one of the dominant cyanobacterial types in the mat. This organism is capable of rapid gliding, forms raft-like structures, produces an extracellular sheath, and secretes copious amounts of mucus. The remarkable clogging capacity of P. autumnale is thought to be related to these features. Another cyanobacterium, which predominates in the mats during the summer, does not express this combination of features and its clogging capacity is much lower.
The recharge basins are normally flooded with effluent for 24 h and dried for 48 h. In a simulation experiment clogging was enhanced when cyanobacterial mats were not allowed to dry thoroughly between floodings. Alteration of the recharge regime to 10 h of flooding during the night only, followed by 38 h of drying, enabled temporal separation of light availability and water availability. Under this regime the development of cyanobacterial mats was significantly retarded. It is concluded that night-flooding can alleviate the operational problems associated with clogging of the recharge basins by cyanobacterial mats. 相似文献
Three cyanobacterial types were isolated and their clogging capacity was determined in a simulation system. Simulation experiments were also used to study the effects of various flooding regimes on mat development and permeability.
In the recharge basins, clogging events have occurred in the autumn, winter or spring. During these seasons, Phormidium autumnale was found to be one of the dominant cyanobacterial types in the mat. This organism is capable of rapid gliding, forms raft-like structures, produces an extracellular sheath, and secretes copious amounts of mucus. The remarkable clogging capacity of P. autumnale is thought to be related to these features. Another cyanobacterium, which predominates in the mats during the summer, does not express this combination of features and its clogging capacity is much lower.
The recharge basins are normally flooded with effluent for 24 h and dried for 48 h. In a simulation experiment clogging was enhanced when cyanobacterial mats were not allowed to dry thoroughly between floodings. Alteration of the recharge regime to 10 h of flooding during the night only, followed by 38 h of drying, enabled temporal separation of light availability and water availability. Under this regime the development of cyanobacterial mats was significantly retarded. It is concluded that night-flooding can alleviate the operational problems associated with clogging of the recharge basins by cyanobacterial mats. 相似文献
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Goldstein LH Dolinsky G Greenberg R Schaefer C Cohen-Kerem R Diav-Citrin O Malm H Reuvers-Lodewijks ME Rost van Tonningen-van Driel MM Arnon J Ornoy A Clementi M Di Gianantonio E Koren G Braunstein R Berkovitch M 《Birth defects research. Part A, Clinical and molecular teratology》2007,79(10):696-701
BACKGROUND: Azathioprine (AZP) interferes with nucleic acid synthesis and is teratogenic in animals. In view of the paucity of information on the use of AZP during pregnancy we investigated this subject in a prospective, controlled, multicenter study. Our objective was too determine whether exposure to AZP during pregnancy increases the risk for major malformations and to determine the effect on pregnancy outcome. METHODS: Pregnant women on AZP who contacted one of seven teratogen information services were compared to a cohort of pregnant women who contacted two of the seven teratogen information services and took nonteratogenic treatments during their pregnancy. RESULTS: Follow-up was completed on 189 women in the AZP group and compared to 230 women in the control group. The rate of major malformations did not differ between groups with six neonates in each; the AZP rate was 3.5% and the control group rate was 3.0% (p = .775; OR 1.17; CI: 0.37, 3.69). The mean birth weight and gestational age were lower in the AZP group (2,995 g vs. 3,252 g [p = .001, difference of mean: 257, 95% CI: 106.3, 408.1] and 37.8 weeks vs. 39.1 weeks [p = .001, difference of mean: 1.3, 95% CI: .5, 2.0], respectively). The AZP group had more cases of prematurity (21.4% vs. 5.2% [p < .001; OR 4.0; 95% CI: 2.0, 8.06]) and low birth weight (23% vs. 6.0% [p < .001; OR 3.81; 95% CI: 2.0, 7.2]). CONCLUSIONS: These results suggest that AZP (50-100 mg/day) does not triple the rate of birth defects; however, it is associated with lower birth weight, gestational age, and prematurity. Larger studies are needed to confirm these observations. 相似文献
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Daniel A. Henk Revital Shahar-Golan Khuraijam Ranjana Devi Kylie J. Boyce Nengyong Zhan Natalie D. Fedorova William C. Nierman Po-Ren Hsueh Kwok-Yung Yuen Tran P. M. Sieu Nguyen Van Kinh Heiman Wertheim Stephen G. Baker Jeremy N. Day Nongnuch Vanittanakom Elaine M. Bignell Alex Andrianopoulos Matthew C. Fisher 《PLoS pathogens》2012,8(10)
Molecular genetic approaches typically detect recombination in microbes regardless of assumed asexuality. However, genetic data have shown the AIDS-associated pathogen Penicillium marneffei to have extensive spatial genetic structure at local and regional scales, and although there has been some genetic evidence that a sexual cycle is possible, this haploid fungus is thought to be genetically, as well as morphologically, asexual in nature because of its highly clonal population structure. Here we use comparative genomics, experimental mixed-genotype infections, and population genetic data to elucidate the role of recombination in natural populations of P. marneffei. Genome wide comparisons reveal that all the genes required for meiosis are present in P. marneffei, mating type genes are arranged in a similar manner to that found in other heterothallic fungi, and there is evidence of a putatively meiosis-specific mutational process. Experiments suggest that recombination between isolates of compatible mating types may occur during mammal infection. Population genetic data from 34 isolates from bamboo rats in India, Thailand and Vietnam, and 273 isolates from humans in China, India, Thailand, and Vietnam show that recombination is most likely to occur across spatially and genetically limited distances in natural populations resulting in highly clonal population structure yet sexually reproducing populations. Predicted distributions of three different spatial genetic clusters within P. marneffei overlap with three different bamboo rat host distributions suggesting that recombination within hosts may act to maintain population barriers within P. marneffei. 相似文献
35.
Thomas S Thiery E Aflalo R Vayssettes C Verney C Berthuy I Créau N 《Gene expression patterns : GEP》2003,3(1):93-97
PCP4 (PEP-19) belongs to a family of proteins involved in calcium transduction signals and binds calmodulin via an IQ motif, in a calcium independent manner. PCP4 gene maps to murine chromosome 16 and in human to chromosome 21. Murine PCP4 expression in the brain has been detected by Northern blot analysis to be mainly post-natal and in the adult to have a neuronal pattern. To investigate if it might have a role earlier in development, we analyzed its expression during mouse embryogenesis by in situ hybridization from E7.5 post-coitum (p.c.) to E17.5 p.c., and in P0 brain. Early, at E7.5, a high expression is restricted to the extra embryonic ectoderm. Embryonic expression starts at E9.5. At E10.5, PCP4 shows a strong signal in the post-mitotic cells of the diencephalon, the metencephalon and the myelencephalon and in the dorsal and cranial ganglia. The floor plate is also densely labelled. At E17.5, PCP4 is expressed in the central nervous system, in the myenteric plexus, and in other ectoderm derivatives, for instance the lens, the hairy cells of the cochlea, the enamel organ and the hair follicles. Thus, during embryogenesis PCP4 is mainly expressed in ectoderm and neuroectoderm comprising neural crest derived cells. 相似文献
36.
Shamri R Grabovsky V Feigelson SW Dwir O Van Kooyk Y Alon R 《The Journal of biological chemistry》2002,277(42):40027-40035
VLA-4 and LFA-1 are the major vascular integrins expressed on circulating lymphocytes. Previous studies suggested that intact cholesterol rafts are required for integrin adhesiveness in different leukocytes. We found the alpha(4) integrins VLA-4 and alpha(4)beta(7) as well as the LFA-1 integrin to be excluded from rafts of human peripheral blood lymphocytes. Disruption of cholesterol rafts with the chelator methyl-beta-cyclodextrin did not affect the ability of these lymphocyte integrins to generate high avidity to their respective endothelial ligands and to promote lymphocyte rolling and arrest on inflamed endothelium under shear flow. In contrast, cholesterol extraction abrogated rapid chemokine triggering of alpha(4)-integrin-dependent peripheral blood lymphocytes adhesion, a process tightly regulated by G(i)-protein activation of G protein-coupled chemokine receptors (GPCR). Strikingly, stimulation of LFA-1 avidity to intercellular adhesion molecule 1 (ICAM-1) by the same chemokines, although G(i)-dependent, was insensitive to raft disruption. Our results suggest that alpha(4) but not LFA-1 integrin avidity stimulation by chemokines involves rapid chemokine-induced GPCR rearrangement that takes place at cholesterol raft platforms upstream to G(i) signaling. Our results provide the first evidence that a particular chemokine/GPCR pair can activate different integrins on the same cell using distinct G(i) protein-associated machineries segregated within defined membrane compartments. 相似文献
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Recombinant human acetylcholinesterase is secreted from transiently transfected 293 cells as a soluble globular enzyme 总被引:5,自引:0,他引:5
Baruch Velan Chanoch Kronman Haim Grosfeld Moshe Leitner Yehoshua Gozes Yehuda Flashner Tamar Sery Sara Cohen Revital Ben-Aziz Shlomo Seidman Avigdor Shafferman Hermona Soreq 《Cellular and molecular neurobiology》1991,11(1):143-156
1. Coding sequences for the human acetylcholinesterase (HuAChE; EC 3.1.1.7) hydrophilic subunit were subcloned in an expression plasmid vector under the control of cytomegalovirus IE gene enhancer-promoter. The human embryonic kidney cell line 293, transiently transfected with this vector, expressed catalytically active acetylcholinesterase. 2. The recombinant gene product exhibits biochemical traits similar to native "true" acetylcholinesterase as manifested by characteristic substrate inhibition, a Km of 117 microM toward acetylthiocholine, and a high sensitivity to the specific acetylcholinesterase inhibitor BW284C51. 3. The transiently transfected 293 cells (100 mm dish) produce in 24 hr active enzyme capable of hydrolyzing 1500 nmol acetylthiocholine per min. Eighty percent of the enzymatic activity appears in the cell growth medium as soluble acetylcholinesterase; most of the cell associated activity is confined to the cytosolic fraction requiring neither detergent nor high salt for its solubilization. 4. The active secreted recombinant enzyme appears in the monomeric, dimeric, and tetrameric globular hydrophilic molecular forms. 5. In conclusion, the catalytic subunit expressed from the hydrophilic AChE cDNA species has the inherent potential to be secreted in the soluble globular form and to generate polymorphism through self-association. 相似文献
38.
Investigating the cardiac pathology of SCO2‐mediated hypertrophic cardiomyopathy using patients induced pluripotent stem cell–derived cardiomyocytes 下载免费PDF全文
Tova Hallas Binyamin Eisen Yuval Shemer Ronen Ben Jehuda Lucy N. Mekies Shulamit Naor Revital Schick Sivan Eliyahu Irina Reiter Eugene Vlodavsky Yeshayahu Katz Katrin ?unap Avraham Lorber Richard Rodenburg Hanna Mandel Mihaela Gherghiceanu Ofer Binah 《Journal of cellular and molecular medicine》2018,22(2):913-925
Mutations in SCO2 are among the most common causes of COX deficiency, resulting in reduced mitochondrial oxidative ATP production capacity, often leading to hypertrophic cardiomyopathy (HCM). To date, none of the recent pertaining reports provide deep understanding of the SCO2 disease pathophysiology. To investigate the cardiac pathology of the disease, we were the first to generate induced pluripotent stem cell (iPSC)‐derived cardiomyocytes (iPSC‐CMs) from SCO2‐mutated patients. For iPSC generation, we reprogrammed skin fibroblasts from two SCO2 patients and healthy controls. The first patient was a compound heterozygote to the common E140K mutation, and the second was homozygote for the less common G193S mutation. iPSC were differentiated into cardiomyocytes through embryoid body (EB) formation. To test the hypothesis that the SCO2 mutation is associated with mitochondrial abnormalities, and intracellular Ca2+‐overload resulting in functional derangements and arrhythmias, we investigated in SCO2‐mutated iPSC‐CMs (compared to control cardiomyocytes): (i) the ultrastructural changes; (ii) the inotropic responsiveness to β‐adrenergic stimulation, increased [Ca2+]o and angiotensin‐II (AT‐II); and (iii) the Beat Rate Variability (BRV) characteristics. In support of the hypothesis, we found in the mutated iPSC‐CMs major ultrastructural abnormalities and markedly attenuated response to the inotropic interventions and caffeine, as well as delayed afterdepolarizations (DADs) and increased BRV, suggesting impaired SR Ca2+ handling due to attenuated SERCA activity caused by ATP shortage. Our novel results show that iPSC‐CMs are useful for investigating the pathophysiological mechanisms underlying the SCO2 mutation syndrome. 相似文献
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We present what is, to our knowledge, a new methodology for high-resolution three-dimensional imaging of oxygen concentration near live cells. The cells are placed in the buffer solution of a stable paramagnetic probe, and electron spin-resonance microimaging is employed to map out the probe's spin-spin relaxation time (T2). This information is directly linked to the concentration of the oxygen molecule. The method is demonstrated with a test sample and with a small amount of live photosynthetic cells (cyanobacteria), under conditions of darkness and light. Spatial resolution of ∼30 × 30 × 100 μm is demonstrated, with ∼μM oxygen concentration sensitivity and sub-fmol absolute oxygen sensitivity per voxel. The use of electron spin-resonance microimaging for oxygen mapping near cells complements the currently available techniques based on microelectrodes or fluorescence/phosphorescence. Furthermore, with the proper paramagnetic probe, it will also be readily applicable for intracellular oxygen microimaging, a capability which other methods find very difficult to achieve. 相似文献