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2.
Working with a Streptomyces albus strain that had previously been bred to produce industrial amounts (10 mg/ml) of salinomycin, we demonstrated the efficacy of introducing drug resistance-producing mutations for further strain improvement. Mutants with enhanced salinomycin production were detected at a high incidence (7 to 12%) among spontaneous isolates resistant to streptomycin (Str r), gentamicin, or rifampin (Rif r). Finally, we successfully demonstrated improvement of the salinomycin productivity of the industrial strain by 2.3-fold by introducing a triple mutation. The Str r mutant was shown to have a point mutation within the rpsL gene (encoding ribosomal protein S12). Likewise, the Rif r mutant possessed a mutation in the rpoB gene (encoding the RNA polymerase β subunit). Increased productivity of salinomycin in the Str r mutant (containing the K88R mutation in the S12 protein) may be a result of an aberrant protein synthesis mechanism. This aberration may manifest itself as enhanced translation activity in stationary-phase cells, as we have observed with the poly(U)-directed cell-free translation system. The K88R mutant ribosome was characterized by increased 70S complex stability in low Mg 2+ concentrations. We conclude that this aberrant protein synthesis ability in the Str r mutant, which is a result of increased stability of the 70S complex, is responsible for the remarkable salinomycin production enhancement obtained. 相似文献
3.
Social, economic and environmental coherence is sought in the management of livestock wastewater. Wetlands facilitate the biogeochemical processes that exploit livestock wastewater and provide opportunities to achieve such coherence and also to deliver on a range of ecosystem services. The Integrated Constructed Wetland (ICW) concept integrates three inextricably linked objectives: water quantity and quality management, landscape-fit to improve aesthetic site values and enhanced biodiversity. The synergies derived from this explicit integration allow one of the key challenges for livestock management to be addressed. An example utilizing twelve ICW systems from a catchment on the south coast of Ireland demonstrates that over an eight year period mean reduction of total and soluble phosphorus (molybdate reactive phosphorus) exceeded 95% and the mean removal of ammonium-N exceeded 98%. This paper reviews evidence regarding the capacity of ICWs to provide a coherent and sustainable alternative to conventional systems. 相似文献
4.
Mesenchymal stem cells (MSCs) have a capacity to differentiate into the chondrogenic lineage and are a valuable allogenic source for cartilage tissue engineering. However, they still have critical limitations of relatively inefficient chondrogenic differentiation in vitro and of dedifferentiation and/or hypertrophic changes at late stages of differentiation. Numerous approaches using biochemical and mechanical factors have been tried but have so far failed to overcome these problems. Recent studies by other groups and ours have shown that low-intensity ultrasound (LIUS) is an efficient tool for promoting the chondrogenic differentiation of MSCs both in vitro and in vivo. A series of our experiments suggests that LIUS not only induces chondrogenic differentiation of MSCs but also has diverse additional activities that enhance the viability of MSCs, increase possibly the integrity of the differentiated tissues and delays hypertrophic changes during differentiation. Therefore, LIUS could be an innovative and versatile tool for chondrogenic differentiation of MSCs and for cartilage tissue engineering. 相似文献
6.
BackgroundWater Sensitive Urban Design (WSUD) systems are frequently used as part of a stormwater harvesting treatment trains (e.g. biofilters (bio-retentions and rain-gardens) and wetlands). However, validation frameworks for such systems do not exist, limiting their adoption for end-uses such as drinking water. The first stage in the validation framework is pre-validation, which prepares information for further validation monitoring. ObjectivesA pre-validation roadmap, consisting of five steps, is suggested in this paper. Detailed methods for investigating target micropollutants in stormwater, and determining challenge conditions for biofilters and wetlands, are provided. MethodsA literature review was undertaken to identify and quantify micropollutants in stormwater. MUSIC V5.1 was utilized to simulate the behaviour of the systems based on 30-year rainfall data in three distinct climate zones; outputs were evaluated to identify the threshold of operational variables, including length of dry periods (LDPs) and volume of water treated per event. ResultsThe paper highlights that a number of micropollutants were found in stormwater at levels above various worldwide drinking water guidelines (eight pesticides, benzene, benzo(a)pyrene, pentachlorophenol, di-(2-ethylhexyl)-phthalate and a total of polychlorinated biphenyls). The 95 th percentile LDPs was exponentially related to system design area while the 5 th percentile length of dry periods remained within short durations (i.e. 2–8 hours). 95 th percentile volume of water treated per event was exponentially related to system design area as a percentage of an impervious catchment area. ConclusionsThe out-comings of this study show that pre-validation could be completed through a roadmap consisting of a series of steps; this will help in the validation of stormwater treatment systems. 相似文献
7.
Discharging of non-treated oily sludge from oil refineries has undesirable impacts on the environment. In this research, the biotreatment of total petroleum hydrocarbons (TPHs) from Abadan Petroleum Refinery, Iran was done using co-composting method. A 5 kg mixture of oily sludge and compost (oily sludge: compost ratios 1:0, 1:0.1, 1:0.3, 1:0.5, and 1:0.7 w/w) and a bulking agent of wheat straw were used as treatments. All treatments were placed in a wooden box inside a laboratory and aerated every 2–3 days by mixing during two months of the experiments. The variation of TPHs concentration, bacterial density, C/N ratio, pH, and temperature were assessed during the 63 days- experiments. Results showed that the majority of TPHs of samples was removed at first 30 days. The maximum TPHs removal (65%) was obtained in the sludge: compost = 1:0.5 at the operation time of 63 day. The significant different between removal efficiency of oily sludge: compost ratios and the control sample (p value < 0.05) indicated the appropriate density of TPHs degrader-bacteria in treated samples. The highest variation in C/N ratio was observed 15± 0.58 in the oily sludge: compost = 1:0.1. At the beginning of experiments, the pH values of all treatments was alkaline, but became neutral at the end of the reaction time. The TPHs degradation kinetic for all oily sludge: compost ratios followed pseudo second-order model. In general, co-composting has high efficiency in oily sludge remediation and can be potentially applied as a simple and cost-effective approach for remediation of oily sludge. 相似文献
8.
Several species of stenodermatine bats congregate in large numbers at collpas in southeastern Peru to drink water. We conducted the first experimental tests of preference for collpa water by representative bats. Artibeus species preferred mineral-rich collpa water over water from other sources, supporting the hypothesis that they seek resources (especially sodium) at collpas. 相似文献
9.
Despite years of research, Alzheimer’s disease (AD) remains incurable and thus poses a major health challenge in coming years. This neurodegenerative disease belongs to a heterogeneous group of human tauopathies, characterized by the extracellular deposition of beta amyloid-Aβ and intracellular accumulation of tau protein in neuronal and glial cells, whereby tau pathology best correlates with disease progression. For decades, several disease-modifying agents were brought to clinical studies with promising efficacy in preclinical trials; however, all of the subsequent clinical trials failed. Therefore, the pursuit for therapeutic agents for the treatment of AD and other tauopathies still continue. Recent evidences show previously unidentified role of peripheral immune system in regulating the inflammatory status of the brain, mainly the dendritic cells. A decrease in functionality and count of dendritic cells has been observed in Alzheimer’s disease. Here, we discuss a potential role of dendritic cell-based vaccines as therapeutic approach in ameliorating disease pathogenesis in AD and other tauopathies. 相似文献
10.
Uncertainties about future conditions and the effects of chosen actions, as well as increasing resource scarcity, have been driving forces in the utilization of adaptive management strategies. However, many applications of adaptive management have been criticized for a number of shortcomings, including a limited ability to learn from actions and a lack of consideration of stakeholder objectives. To address these criticisms, we supplement existing adaptive management approaches with a decision-analytical approach that first informs the initial selection of management alternatives and then allows for periodic re-evaluation or phased implementation of management alternatives based on monitoring information and incorporation of stakeholder values. We describe the application of this enhanced adaptive management (EAM) framework to compare remedial alternatives for mercury in the South River, based on an understanding of the loading and behavior of mercury in the South River near Waynesboro, VA. The outcomes show that the ranking of remedial alternatives is influenced by uncertainty in the mercury loading model, by the relative importance placed on different criteria, and by cost estimates. The process itself demonstrates that a decision model can link project performance criteria, decision-maker preferences, environmental models, and short- and long-term monitoring information with management choices to help shape a remediation approach that provides useful information for adaptive, incremental implementation. 相似文献
12.
Hypereutrophication of U.S. surface waters is one of the leading causes of impairment for water quality. With nutrient criteria development and total maximum daily load (TMDL) issues looming for regulators, agricultural research is focusing on practices aimed at decreasing nutrient contributions to receiving aquatic ecosystems. This study examined the use of rice ( Oryza sativa) for luxury uptake of nitrogen and phosphorus components associated with agricultural storm runoff. Mesocosms (379 L) planted with rice were exposed to two concentrations (5 and 10 mg/L) of nitrate, ammonia, and orthophosphorus. Results from these mesocosms were compared to unvegetated controls (also amended with 5 or 10 mg/L nitrate, ammonia, and orthophosphorus) to determine efficiency of rice in remediating nutrient runoff. Statistically significant differences in ammonia and nitrate retention of vegetated mesocosms amended with 5 mg/L versus vegetated mesocosms amended with 10 mg/L were noted after the first exposure. Although rice is a nutrient-dependent aquatic plant, this study suggests that more efficient mitigation is possible at lower inflow concentrations as opposed to higher inflow concentrations. 相似文献
13.
Hyperinsulinemia and exaggerated insulin response to glucose are among the hallmarks of obesity. However, the role of hyperinsulinemia in the etiology and maintenance of obesity has been controversial. If hyperinsulinemia plays a critical role as proposed, then its reversal may have therapeutic potential. To test this hypothesis, the activity of Ro 23–7637, {4-(2,2-diphenylethenyl)-1-[1-oxo-9-(3-pyridinyl) nonyl]piperidine}, which partially normalizes plasma insulin by an action on pancreatic islets from obese rats, was assessed. When islets were cultured for 2 days with 10 μM Ro 23–7637, a significant reduction in the exaggerated glucose-induced insulin secretion was observed. When islets from lean rats were exposed to Ro 23–7637, no reduction in insulin secretion was observed. The effects of oral administration of Ro 23–7637 were assessed in Zucker and diet-induced obese rats in doses ranging from 5 to 90 mg/kg/day. Dose-related reductions were observed in: 1) glucose-induced insulin secretion; 2) basal insulin concentration; 3) daily food intake; and 4) body weight gain. In diet-induced obese rats, selective mobilization of fat, maintenance of body protein, and decreased energetic efficiency were also observed. An association between the partial normalization of glucose-induced insulin responses and reductions of basal insulin, reduced rates of body weight gain or body weight loss and decreased food intake was observed in obese rats. Therefore, these studies indicate that Ro 23–7637 is an orally active, efficacious antiobesity agent. 相似文献
14.
Glaucoma is a neurodegenerative disease and second leading cause of blindness in western world. The disease is characterized by an elevated intraocular pressure. Carbonic anhydrase plays a major role by forming aqueous humor and its inhibition can reduce intraocular pressure by partially suppressing the secretion of aqueous humor. Thus in this study, we proposed to identify the potential novel compounds targeting the carbonic anhydrase. The diversity set-II molecules library consisting of 1880 compounds from National Cancer Institute were virtually screened (molecular docking) against human carbonic anhydrase protein. For the obtained best compounds, the nature of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), which determine nucleophilic and electrophilic activity, were calculated by using density functional theory (DFT). The in silico screening suggested 5 best compounds that are effective in comparison to the dorzolamide, a widely used carbonic anhydrase inhibitor for glaucoma treatment. Of the five compounds, 4-nitro-7-[(1-oxidopyridin-1-ium-2-yl) thio] benzofurazan (ZINC01757986) exhibited the better binding affinity (??9.2 cal/mol) in comparison to dorzolamide (??7.2 kcal/mol). The DFT studies on novel identified compound, ZINC01757986 exhibited less HOMO–LUMO energy gap, low hardness and more softness (0.2305 eV, 0.1152 eV and 8.6805 eV) when compared to dorzalamide (0.9536 eV, 0.4768 eV and 2.0973 eV). These studies emphasize that ZINC01757986 can be used as potential carbonic anhydrase inhibitor and lead compounds for the development of an effective anti-glaucoma drug. The results emphasize that these compounds could be potential lead molecules for further structure-based discovery of antiglaucoma drugs. 相似文献
15.
This paper represents the culmination of a four-year ethnographic research project in a leading U.K. manufacturing company. A number of organizational deficiencies in the new product introduction (NPI) process are identified. Proposals subsequently are implemented that enhance the effectiveness of this process. The paper identifies the critical need for organizations to communicate effectively among different functional areas with respect to new products. A review of modeling techniques identifies the GRAI grid as an effective model for analyzing and improving cooperative business processes. The GRAI grid is set within the framework of a novel implementation methodology and subsequently is applied to the NPI process within the collaborating company. The paper concludes by reporting the substantial benefits gained. 相似文献
16.
A highly enantioselective methodology for the synthesis of the GABA(B) receptor agonist (R)-(-)-baclofen is described. This synthesis begins with p-chlorophenethyl alcohol and involves a catalytic carbon-hydrogen insertion reaction of a chiral dirhodium(II) carboxamidate with the corresponding diazoacetate (81% yield, 95% ee). Subsequent steps convert the intermediate gamma-lactone to (R)- (-)-baclofen in a 60% overall yield. The amount of catalyst required for the C-H insertion transformation is only 0.5 mol%. 相似文献
17.
Altered activity of the hypothalamic pituitary adrenal (HPA) axis is one of the most commonly observed neuroendocrine abnormalities
in patients suffering from major depressive disorder (MDD). Altered cortisol secretion can be found in as many as 80% of depressed
patients. This observation has led to intensive clinical and preclinical research aiming to better understand the molecular
mechanisms which underlie the alteration of the HPA axis responsiveness in depressive illness. Dysfunctional glucocorticoid
receptor (GR) mediated negative feedback regulation of cortisol levels and changes in arginine vasopressin (AVP)/vasopressin
V 1b receptor and corticotrophin-releasing factor/CRF 1 receptor regulation of adrenocotricotrophin (ACTH) release have all been implicated in over-activity of the HPA axis. Agents
that intervene with the mechanisms involved in (dys)regulation of cortisol synthesis and release are under investigation as
possible therapeutic agents. The current status of some of these approaches is described in this review.
Special issue article in honor of George Fink. 相似文献
18.
正Transposable elements(TEs)make up nearly half of the mammalian genome.Recent probabilistic re-annotation of genome sequences indicated that as much as two-thirds or more of the human genome may be derived from TEs(de Koning et al.,2011).Their ability to mobilize in the genome represents a constant threat to the host by creating insertion mutations,which may lead to progressive deterioration of genetic information.To counteract this threat,host cells 相似文献
19.
Dichlorodihydrofluorescein (DCFH(2)) is a widely used probe for intracellular H(2)O(2). However, H(2)O(2) can oxidize DCFH(2) only in the presence of a catalyst, whose identity in cells has not been clearly defined. We compared the peroxidase activity of Cu,Zn-superoxide dismutase (CuZnSOD), cytochrome c, horseradish peroxidase (HRP), Cu(2+), and Fe(3+) under various condi-tions to identify an intracellular catalyst. Enormous increase by bicarbonate in the rate of DCFH(2) oxidation distinguished CuZnSOD from cytochrome c and HRP. Cyanide inhibited the reaction catalyzed by CuZnSOD but accelerated that by Cu(2+) and Fe(3+). Oxidation of DCFH(2) by H(2)O(2) in the presence of a cell lys-ate was also enhanced by bicarbonate and inhibited by cyanide. Confocal microscopy of H(2)O(2)-treated cells showed enhanced DCF fluorescence in the presence of bicarbonate and attenuated fluorescence for the cells pre-incubated with KCN. Moreover, DCF fluorescence was intensified in CuZnSOD-transfected HaCaT and RAW 264.7 cells. We propose that CuZnSOD is a potential intracellular catalyst for the H(2)O(2)-dependent oxidation of DCFH(2). 相似文献
20.
Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, −84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this is the first report of C. meleagridis from Ireland.Demand for high-quality drinking and recreational waters rises exponentially due to global demographic growth in the human population, reinforcing an urgent need for microbiologically safe reclaimed waters ( 12). Wastewater discharges are worldwide risk factors for the introduction of human pathogens into surface waters used as drinking and recreational resources. Cryptosporidium parvum, C. hominis, Giardia duodenalis, and human-virulent microsporidia (i.e., Encephalitozoon intestinalis, E. hellem, E. cuniculi, and Enterocytozoon bieneusi) are waterborne enteropathogens inflicting considerable morbidity in healthy people and mortality (e.g., Cryptosporidium and microspora) in immunodeficient individuals ( 34, 44). Their transmissive stages, i.e., oocysts, cysts, and spores, are resistant to environmental stressors and are therefore long-lasting and relatively ubiquitous in the environment ( 13, 27, 45). These pathogens are category B biodefense agents on the U.S. National Institutes of Health list, and microsporidian spores are on the Contaminant Candidate List of the U.S. Environmental Protection Agency ( 29) because spore identification, removal, and inactivation in drinking water are technologically challenging. Surface water is not routinely monitored for these pathogens, despite evidence demonstrating environmental contamination derived from wastewater discharges ( 12). Environmentally, all aforementioned pathogens (except C. hominis) have a broad zoonotic reservoir ( 13, 27, 34).Constructed wetlands of either vertical or horizontal flow are increasingly used worldwide for secondary or tertiary treatment of municipal wastewater due to minimum electric requirements and low maintenance costs ( 6, 32). The wetland concept has become an attractive wastewater treatment alternative to conventional tertiary treatment processes for (i) municipal wastewater, (ii) on-site domestic wastewater treatment, and (iii) concentrated animal feeding operations ( 24). In wetlands, human-pathogenic microorganisms are physically removed and biodegraded by sedimentation ( 2, 23), filtration and evapotranspiration-driven attachment to plant roots ( 10, 43), natural die-off ( 28), UV radiation, straining and sorption by biofilm ( 31), and protozoan predation ( 37). It is thought that the performance of subsurface flow (SSF) wetlands in removing human pathogens is superior to that of secondary wastewater treatment, i.e., conventional sewage sludge activation ( 40). Horizontal wetlands usually discharge to surface waters that are frequently used for recreation or drinking water production ( 6). It is commonly assumed that human pathogens identified in wetland effluents originate from the wastewater ( 39). However, this was never proven because studies of human pathogens in wetlands ( 10, 23, 28, 31, 32, 39, 40) did not utilize molecular epidemiology techniques to differentiate pathogen species or assess their viability.In general, wastewater can be injected under the wetland surface for plug flow hydraulics, i.e., SSF ( 43), or be delivered to the wetland surface for free-surface flow (FSF). Because the wastewater resides in wetlands, these areas can act as endemic sites supporting both propagation and transmission of human zoonotic pathogens ( 15). Sizing reed-bed systems for a residence time of 5 days has become a standard practice ( 6, 31, 39), leaving plenty of time for the propagation and spreading of wastewater-derived pathogens in wetland habitats via a wide variety of wildlife ( 12, 15). Any temporal or permanent malfunctioning caused by clogged inlet pipes can cause (i) hydraulic short circuits that bypass part of the filtration area in FSF wetlands or (ii) chance SSF wetland filtration dynamics to FSF dynamics ( 31, 40). This can additionally increase wastewater retention time in wetlands.The purposes of the present study were to (i) determine species of human protozoan and fungal enteropathogens entering, residing, and leaving constructed horizontal wetlands used for tertiary treatment of municipal wastewater; (ii) determine the efficacy for removal of Cryptosporidium oocysts, G. duodenalis cysts, and human-virulent microsporidian spore species by wetlands from wastewater subjected to secondary treatment; and (iii) compare pathogen removal efficacies between SSF and FSF wetlands. We used a multiplexed fluorescence in situ hybridization (FISH) assay with immunofluorescence antibody (IFA) to identify C. parvum and C. hominis oocysts and microsporidian spores and to assess their viability in a quantitative manner. Since multiplexed FISH specifically identifies C. parvum and C. hominis oocysts but does not differentiate between these species ( 36), we used PCR-restriction fragment length polymorphism (RFLP) to identify other potential oocyst species. In addition, we used PCR to confirm species of microsporidian spores identified by FISH. 相似文献
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