Enhanced Endosomal Escape by Light-Fueled Liquid-Metal Transformer.

PubMed

Lu, Yue; Lin, Yiliang; Chen, Zhaowei; Hu, Quanyin; Liu, Yang; Yu, Shuangjiang; Gao, Wei; Dickey, Michael D; Gu, Zhen

2017-04-12

Effective endosomal escape remains as the "holy grail" for endocytosis-based intracellular drug delivery. To date, most of the endosomal escape strategies rely on small molecules, cationic polymers, or pore-forming proteins, which are often limited by the systemic toxicity and lack of specificity. We describe here a light-fueled liquid-metal transformer for effective endosomal escape-facilitated cargo delivery via a chemical-mechanical process. The nanoscale transformer can be prepared by a simple approach of sonicating a low-toxicity liquid-metal. When coated with graphene quantum dots (GQDs), the resulting nanospheres demonstrate the ability to absorb and convert photoenergy to drive the simultaneous phase separation and morphological transformation of the inner liquid-metal core. The morphological transformation from nanospheres to hollow nanorods with a remarkable change of aspect ratio can physically disrupt the endosomal membrane to promote endosomal escape of payloads. This metal-based nanotransformer equipped with GQDs provides a new strategy for facilitating effective endosomal escape to achieve spatiotemporally controlled drug delivery with enhanced efficacy.

Microbial exopolysaccharide-mediated synthesis and stabilization of metal nanoparticles.

PubMed

Sathiyanarayanan, Ganesan; Dineshkumar, Krishnamoorthy; Yang, Yung-Hun

2017-11-01

Exopolysaccharides (EPSs) are structurally and functionally valuable biopolymer secreted by different prokaryotic and eukaryotic microorganisms in response to biotic/abiotic stresses and to survive in extreme environments. Microbial EPSs are fascinating in various industrial sectors due to their excellent material properties and less toxic, highly biodegradable, and biocompatible nature. Recently, microbial EPSs have been used as a potential template for the rapid synthesis of metallic nanoparticles and EPS-mediated metal reduction processes are emerging as simple, harmless, and environmentally benign green chemistry approaches. EPS-mediated synthesis of metal nanoparticles is a distinctive metabolism-independent bio-reduction process due to the formation of interfaces between metal cations and the polyanionic functional groups (i.e. hydroxyl, carboxyl and amino groups) of the EPS. In addition, the range of physicochemical features which facilitates the EPS as an efficient stabilizing or capping agents to protect the primary structure of the metal nanoparticles with an encapsulation film in order to separate the nanoparticle core from the mixture of composites. The EPS-capping also enables the further modification of metal nanoparticles with expected material properties for multifarious applications. The present review discusses the microbial EPS-mediated green synthesis/stabilization of metal nanoparticles, possible mechanisms involved in EPS-mediated metal reduction, and application prospects of EPS-based metal nanoparticles.

Metal-metal interaction mediates the iron induction of Drosophila MtnB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiang, Wenjia; Huang, Yunpeng; Wan, Zhihui

Metallothionein (MT) protein families are a class of small and universal proteins rich in cysteine residues. They are synthesized in response to heavy metal stresses to sequester the toxic ions by metal-thiolate bridges. Five MT family members, namely MtnA, MtnB, MtnC, MtnD and MtnE, have been discovered and identified in Drosophila. These five isoforms of MTs are regulated by metal responsive transcription factor dMTF-1 and play differentiated but overlapping roles in detoxification of metal ions. Previous researches have shown that Drosophila MtnB responds to copper (Cu), cadmium (Cd) and zinc (Zn). Interestingly in this study we found that Drosophila MtnBmore » expression also responds to elevated iron levels in the diet. Further investigations revealed that MtnB plays limited roles in iron detoxification, and the direct binding of MtnB to ferrous iron in vitro is also weak. The induction of MtnB by iron turns out to be mediated by iron interference of other metals, because EDTA at even a partial concentration of that of iron can suppress this induction. Indeed, in the presence of iron, zinc homeostasis is altered, as reflected by expression changes of zinc transporters dZIP1 and dZnT1. Thus, iron-mediated MtnB induction appears resulting from interrupted homeostasis of other metals such as zinc, which in turns induced MtnB expression. Metal-metal interaction may more widely exist than we expected. - Highlights: • Metallothionein B expression is regulated by iron in Drosophila melanogaster. • MtnB has limited physiological roles in iron detoxification. • Binding affinity of MtnB to iron is weak in vitro. • Induction of Drosophila MtnB by iron is mediated indirectly through metal-metal interaction.« less

Optimization of Agrobacterium-Mediated Transformation in Soybean

PubMed Central

Li, Shuxuan; Cong, Yahui; Liu, Yaping; Wang, Tingting; Shuai, Qin; Chen, Nana; Gai, Junyi; Li, Yan

2017-01-01

High transformation efficiency is a prerequisite for study of gene function and molecular breeding. Agrobacterium tumefaciens-mediated transformation is a preferred method in many plants. However, the transformation efficiency in soybean is still low. The objective of this study is to optimize Agrobacterium-mediated transformation in soybean by improving the infection efficiency of Agrobacterium and regeneration efficiency of explants. Firstly, four factors affecting Agrobacterium infection efficiency were investigated by estimation of the rate of GUS transient expression in soybean cotyledonary explants, including Agrobacterium concentrations, soybean explants, Agrobacterium suspension medium, and co-cultivation time. The results showed that an infection efficiency of over 96% was achieved by collecting the Agrobacterium at a concentration of OD650 = 0.6, then using an Agrobacterium suspension medium containing 154.2 mg/L dithiothreitol to infect the half-seed cotyledonary explants (from mature seeds imbibed for 1 day), and co-cultured them for 5 days. The Agrobacterium infection efficiencies for soybean varieties Jack Purple and Tianlong 1 were higher than the other six varieties. Secondly, the rates of shoot elongation were compared among six different concentration combinations of gibberellic acid (GA3) and indole-3-acetic acid (IAA). The shoot elongation rate of 34 and 26% was achieved when using the combination of 1.0 mg/L GA3 and 0.1 mg/L IAA for Jack Purple and Tianlong 1, respectively. This rate was higher than the other five concentration combinations of GA3 and IAA, with an 18 and 11% increase over the original laboratory protocol (a combination of 0.5 mg/L GA3 and 0.1 mg/L IAA), respectively. The transformation efficiency was 7 and 10% for Jack Purple and Tianlong 1 at this optimized hormone concentration combination, respectively, which was 2 and 6% higher than the original protocol, respectively. Finally, GUS histochemical staining, PCR, herbicide

Optimization of Agrobacterium-Mediated Transformation in Soybean.

PubMed

Li, Shuxuan; Cong, Yahui; Liu, Yaping; Wang, Tingting; Shuai, Qin; Chen, Nana; Gai, Junyi; Li, Yan

2017-01-01

High transformation efficiency is a prerequisite for study of gene function and molecular breeding. Agrobacterium tumefaciens -mediated transformation is a preferred method in many plants. However, the transformation efficiency in soybean is still low. The objective of this study is to optimize Agrobacterium -mediated transformation in soybean by improving the infection efficiency of Agrobacterium and regeneration efficiency of explants. Firstly, four factors affecting Agrobacterium infection efficiency were investigated by estimation of the rate of GUS transient expression in soybean cotyledonary explants, including Agrobacterium concentrations, soybean explants, Agrobacterium suspension medium, and co-cultivation time. The results showed that an infection efficiency of over 96% was achieved by collecting the Agrobacterium at a concentration of OD 650 = 0.6, then using an Agrobacterium suspension medium containing 154.2 mg/L dithiothreitol to infect the half-seed cotyledonary explants (from mature seeds imbibed for 1 day), and co-cultured them for 5 days. The Agrobacterium infection efficiencies for soybean varieties Jack Purple and Tianlong 1 were higher than the other six varieties. Secondly, the rates of shoot elongation were compared among six different concentration combinations of gibberellic acid (GA 3 ) and indole-3-acetic acid (IAA). The shoot elongation rate of 34 and 26% was achieved when using the combination of 1.0 mg/L GA 3 and 0.1 mg/L IAA for Jack Purple and Tianlong 1, respectively. This rate was higher than the other five concentration combinations of GA 3 and IAA, with an 18 and 11% increase over the original laboratory protocol (a combination of 0.5 mg/L GA 3 and 0.1 mg/L IAA), respectively. The transformation efficiency was 7 and 10% for Jack Purple and Tianlong 1 at this optimized hormone concentration combination, respectively, which was 2 and 6% higher than the original protocol, respectively. Finally, GUS histochemical staining, PCR

A comprehensive review of metal-induced cellular transformation studies.

PubMed

Chen, Qiao Yi; Costa, Max

2017-09-15

In vitro transformation assays not only serve practical purposes in screening for potential carcinogenic substances in food, drug, and cosmetic industries, but more importantly, they provide a means of understanding the critical biological processes behind in vivo cancer development. In resemblance to cancer cells in vivo, successfully transformed cells display loss of contact inhibition, gain of anchorage independent growth, resistant to proper cell cycle regulation such as apoptosis, faster proliferation rate, potential for cellular invasion, and ability to form tumors in experimental animals. Cells purposely transformed using metal exposures enable researchers to examine molecular changes, dissect various stages of tumor formation, and ultimately elucidate metal induced cancer mode of action. For practical purposes, this review specifically focuses on studies incorporating As-, Cd-, Cr-, and Ni-induced cell transformation. Through investigating and comparing an extensive list of studies using various methods of metal-induced transformation, this review serves to bridge an information gap and provide a guide for avoiding procedural discrepancies as well as maximizing experimental efficiency. Copyright © 2017 Elsevier Inc. All rights reserved.

Co-metal-organic-frameworks with pure uniform crystal morphology prepared via Co2 + exchange-mediated transformation from Zn-metallogels for luminol catalysed chemiluminescence

NASA Astrophysics Data System (ADS)

Tang, Xue Qian; Xiao, Bo Wen; Li, Chun Mei; Wang, Dong Mei; Huang, Cheng Zhi; Li, Yuan Fang

2017-03-01

Cation exchange-mediated transformation from Zn-metallogels (MOGs), which was a mild facile strategy relative to the demanding hydrothermal method, was employed to develop Co2 + metal-organic frameworks (Co-MOFs) at room temperature. The obtained Co-MOFs was of uniform octahedral morphology and possessed high activity to catalyze luminol chemiluminescence without extra oxidants. By adding cysteine, the CL emission of luminol-Co-MOFs system was further enhanced. Based on this phenomenon, Co-MOFs was utilized to build a practical sensing platform for cysteine determination. Under the optimized conditions, the relative CL intensity (ΔI) was proportional to the concentration of cysteine in the range of 2-10 μM, and the detection limit was 0.49 μM (3S/N). Moreover, the established method was applied to the determination of cysteine in commercially available pharmaceutical injections.

Redox-mediated activation of latent transforming growth factor-beta 1

NASA Technical Reports Server (NTRS)

Barcellos-Hoff, M. H.; Dix, T. A.; Chatterjee, A. (Principal Investigator)

1996-01-01

Transforming growth factor beta 1 (TGF beta) is a multifunctional cytokine that orchestrates response to injury via ubiquitous cell surface receptors. The biological activity of TGF beta is restrained by its secretion as a latent complex (LTGF beta) such that activation determines the extent of TGF beta activity during physiological and pathological events. TGF beta action has been implicated in a variety of reactive oxygen-mediated tissue processes, particularly inflammation, and in pathologies such as reperfusion injury, rheumatoid arthritis, and atherosclerosis. It was recently shown to be rapidly activated after in vivo radiation exposure, which also generates reactive oxygen species (ROS). In the present studies, the potential for redox-mediated LTGF beta activation was investigated using a cell-free system in which ROS were generated in solution by ionizing radiation or metal ion-catalyzed ascorbate reaction. Irradiation (100 Gray) of recombinant human LTGF beta in solution induced 26% activation compared with that elicited by standard thermal activation. Metal-catalyzed ascorbate oxidation elicited extremely efficient recombinant LTGF beta activation that matched or exceeded thermal activation. The efficiency of ascorbate activation depended on ascorbate concentrations and the presence of transition metal ions. We postulate that oxidation of specific amino acids in the latency-conferring peptide leads to a conformation change in the latent complex that allows release of TGF beta. Oxidative activation offers a novel route for the involvement of TGF beta in tissue processes in which ROS are implicated and endows LTGF beta with the ability to act as a sensor of oxidative stress and, by releasing TGF beta, to function as a signal for orchestrating the response of multiple cell types. LTGF beta redox sensitivity is presumably directed toward recovery of homeostasis; however, oxidation may also be a mechanism of LTGF beta activation that can be deleterious during

Efficient Agrobacterium-mediated transformation of the liverwort Marchantia polymorpha using regenerating thalli.

PubMed

Kubota, Akane; Ishizaki, Kimitsune; Hosaka, Masashi; Kohchi, Takayuki

2013-01-01

The thallus, the gametophyte body of the liverwort Marchantia polymorpha, develops clonal progenies called gemmae that are useful in the isolation and propagation of isogenic plants. Developmental timing is critical to Agrobacterium-mediated transformation, and high transformation efficiency has been achieved only with sporelings. Here we report an Agrobacterium-mediated transformation system for M. polymorpha using regenerating thalli. Thallus regeneration was induced by cutting the mature thallus across the apical-basal axis and incubating the basal portion of the thallus for 3 d. Regenerating thalli were infected with Agrobacterium carrying binary vector that contained a selection marker, the hygromycin phosphotransferase gene, and hygromycin-resistant transformants were obtained with an efficiency of over 60%. Southern blot analysis verified random integration of 1 to 4 copies of the T-DNA into the M. polymorpha genome. This Agrobacterium-mediated transformation system for M. polymorpha should provide opportunities to perform genetic transformation without preparing spores and to generate a sufficient number of transformants with isogenic background.

Co-metal-organic-frameworks with pure uniform crystal morphology prepared via Co2+ exchange-mediated transformation from Zn-metallogels for luminol catalysed chemiluminescence.

PubMed

Tang, Xue Qian; Xiao, Bo Wen; Li, Chun Mei; Wang, Dong Mei; Huang, Cheng Zhi; Li, Yuan Fang

2017-03-15

Cation exchange-mediated transformation from Zn-metallogels (MOGs), which was a mild facile strategy relative to the demanding hydrothermal method, was employed to develop Co 2+ metal-organic frameworks (Co-MOFs) at room temperature. The obtained Co-MOFs was of uniform octahedral morphology and possessed high activity to catalyze luminol chemiluminescence without extra oxidants. By adding cysteine, the CL emission of luminol-Co-MOFs system was further enhanced. Based on this phenomenon, Co-MOFs was utilized to build a practical sensing platform for cysteine determination. Under the optimized conditions, the relative CL intensity (ΔI) was proportional to the concentration of cysteine in the range of 2-10μM, and the detection limit was 0.49μM (3S/N). Moreover, the established method was applied to the determination of cysteine in commercially available pharmaceutical injections. Copyright © 2016 Elsevier B.V. All rights reserved.

Advances in Stereoconvergent Catalysis from 2005–2015: Transition-Metal-Mediated Stereoablative Reactions, Dynamic Kinetic Resolutions, and Dynamic Kinetic Asymmetric Transformations

PubMed Central

Bhat, Vikram; Welin, Eric R.; Guo, Xuelei; Stoltz, Brian M.

2017-01-01

An important subset of asymmetric synthesis is dynamic kinetic resolution, dynamic kinetic asymmetric processes and stereoablative transformations. Initially, only enzymes were known to catalyze dynamic kinetic processes but recently various synthetic catalysts have been developed. This review summarizes major advances in non-enzymatic, transition metal promoted dynamic asymmetric transformations reported between 2005 and 2015. PMID:28164696

Agrobacterium tumefaciens-mediated transformation of oleaginous yeast Lipomyces species.

PubMed

Dai, Ziyu; Deng, Shuang; Culley, David E; Bruno, Kenneth S; Magnuson, Jon K

2017-08-01

Interest in using renewable sources of carbon, especially lignocellulosic biomass, for the production of hydrocarbon fuels and chemicals has fueled interest in exploring various organisms capable of producing hydrocarbon biofuels and chemicals or their precursors. The oleaginous (oil-producing) yeast Lipomyces starkeyi is the subject of active research regarding the production of triacylglycerides as hydrocarbon fuel precursors using a variety of carbohydrate and nutrient sources. The genome of L. starkeyi has been published, which opens the door to production strain improvements through the development and use of the tools of synthetic biology for this oleaginous species. The first step in establishment of synthetic biology tools for an organism is the development of effective and reliable transformation methods with suitable selectable marker genes and demonstration of the utility of the genetic elements needed for expression of introduced genes or deletion of endogenous genes. Chemical-based methods of transformation have been published but suffer from low efficiency. To address these problems, Agrobacterium-mediated transformation was investigated as an alternative method for L. starkeyi and other Lipomyces species. In this study, Agrobacterium-mediated transformation was demonstrated to be effective in the transformation of both L. starkeyi and other Lipomyces species. The deletion of the peroxisomal biogenesis factor 10 gene was also demonstrated in L. starkeyi. In addition to the bacterial antibiotic selection marker gene hygromycin B phosphotransferase, the bacterial β-glucuronidase reporter gene under the control of L. starkeyi translation elongation factor 1α promoter was also stably expressed in six different Lipomyces species. The results from this study demonstrate that Agrobacterium-mediated transformation is a reliable and effective genetic tool for homologous recombination and expression of heterologous genes in L. starkeyi and other Lipomyces

Transformational leadership and task cohesion in sport: the mediating role of inside sacrifice.

PubMed

Cronin, Lorcan Donal; Arthur, Calum Alexander; Hardy, James; Callow, Nichola

2015-02-01

In this cross-sectional study, we examined a mediational model whereby transformational leadership is related to task cohesion via sacrifice. Participants were 381 American (Mage = 19.87 years, SD = 1.41) Division I university athletes (188 males, 193 females) who competed in a variety of sports. Participants completed measures of coach transformational leadership, personal and teammate inside sacrifice, and task cohesion. After conducting multilevel mediation analysis, we found that both personal and teammate inside sacrifice significantly mediated the relationships between transformational leadership behaviors and task cohesion. However, there were differential patterns of these relationships for male and female athletes. Interpretation of the results highlights that coaches should endeavor to display transformational leadership behaviors as they are related to personal and teammate inside sacrifices and task cohesion.

Improvement of Agrobacterium-mediated transformation and rooting of black cherry

Treesearch

Ying Wang; Paula M. Pijut

2014-01-01

An improved protocol for Agrobacterium-mediated transformation of an elite, mature black cherry genotype was developed. To increase transformation efficiency, vacuum infiltration, sonication, and a combination of the two treatments were applied during the cocultivation of leaf explants with Agrobacterium tumefaciens strain EHA105...

Novel compounds that enhance Agrobacterium-mediated plant transformation by mitigating oxidative stress.

PubMed

Dan, Yinghui; Zhang, Song; Zhong, Heng; Yi, Hochul; Sainz, Manuel B

2015-02-01

Agrobacterium tumefaciens caused tissue browning leading to subsequent cell death in plant transformation and novel anti-oxidative compounds enhanced Agrobacterium -mediated plant transformation by mitigating oxidative stress. Browning and death of cells transformed with Agrobacterium tumefaciens is a long-standing and high impact problem in plant transformation and the agricultural biotechnology industry, severely limiting the production of transgenic plants. Using our tomato cv. MicroTom transformation system, we demonstrated that Agrobacterium caused tissue browning (TB) leading to subsequent cell death by our correlation study. Without an antioxidant (lipoic acid, LA) TB was severe and associated with high levels of GUS transient expression and low stable transformation frequency (STF). LA addition shifted the curve in that most TB was intermediate and associated with the highest levels of GUS transient expression and STF. We evaluated 18 novel anti-oxidative compounds for their potential to enhance Agrobacterium-mediated transformation, by screening for TB reduction and monitoring GUS transient expression. Promising compounds were further evaluated for their effect on MicroTom and soybean STF. Among twelve non-antioxidant compounds, seven and five significantly (P < 0.05) reduced TB and increased STF, respectively. Among six antioxidants four of them significantly reduced TB and five of them significantly increased STF. The most efficient compound found to increase STF was melatonin (MEL, an antioxidant). Optimal concentrations and stages to use MEL in transformation were determined, and Southern blot analysis showed that T-DNA integration was not affected by MEL. The ability of diverse compounds with different anti-oxidative mechanisms can reduce Agrobacterium-mediated TB and increase STF, strongly supporting that oxidative stress is an important limiting factor in Agrobacterium-mediated transformation and the limiting factor can be controlled by these

Cell transformation mediated by chromosomal deoxyribonucleic acid of polyoma virus-transformed cells.

PubMed Central

Della Valle, G; Fenton, R G; Basilico, C

1981-01-01

To study the mechanism of deoxyribonucleic acid (DNA)-mediated gene transfer, normal rat cells were transfected with total cellular DNA extracted from polyoma virus-transformed cells. This resulted in the appearance of the transformed phenotype in 1 X 10(-6) to 3 X 10(-6) of the transfected cells. Transformation was invariably associated with the acquisition of integrated viral DNA sequences characteristic of the donor DNA. This was caused not by the integration of free DNA molecules, but by the transfer of large DNA fragments (10 to 20 kilobases) containing linked cellular and viral sequences. Although Southern blot analysis showed that integration did not appear to occur in a homologous region of the recipient chromosome, the frequency of transformation was rather high when compared with that of purified polyoma DNA, perhaps due to "position" effects or to the high efficiency of recombination of large DNA fragments. Images PMID:6100965

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process

NASA Astrophysics Data System (ADS)

Feng, Bingmei; Wang, Huixin; Wang, Dongniu; Yu, Huilong; Chu, Yi; Fang, Hai-Tao

2014-11-01

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g-1, twice as high as that of the latter.After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2

Phosphate-Mediated Remediation of Metals and Radionuclides

DOE PAGES

Martinez, Robert J.; Beazley, Melanie J.; Sobecky, Patricia A.

2014-01-01

Worldwide industrialization activities create vast amounts of organic and inorganic waste streams that frequently result in significant soil and groundwater contamination. Metals and radionuclides are of particular concern due to their mobility and long-term persistence in aquatic and terrestrial environments. As the global population increases, the demand for safe, contaminant-free soil and groundwater will increase as will the need for effective and inexpensive remediation strategies. Remediation strategies that include physical and chemical methods (i.e., abiotic) or biological activities have been shown to impede the migration of radionuclide and metal contaminants within soil and groundwater. However, abiotic remediation methods are oftenmore » too costly owing to the quantities and volumes of soils and/or groundwater requiring treatment. The in situ sequestration of metals and radionuclides mediated by biological activities associated with microbial phosphorus metabolism is a promising and less costly addition to our existing remediation methods. This review highlights the current strategies for abiotic and microbial phosphate-mediated techniques for uranium and metal remediation.« less

Metal transformation as a strategy for bacterial detoxification of heavy metals.

PubMed

Essa, Ashraf M M; Al Abboud, Mohamed A; Khatib, Sayeed I

2018-01-01

Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile metabolic products (VMPs) of Escherichia coli Z3 for 24 h using aerobic bioreactor. The effect of the metals treated with VMPs in comparison to the untreated metals on the growth of E. coli S1 and Staphylococcus aureus S2 (local isolates) was examined. Moreover, the toxic properties of the treated and untreated metals were monitored using minimum inhibitory concentration assay. A marked reduction of the treated metals toxicity was recorded in comparison to the untreated metals. Scanning electron microscopy and energy dispersive X-ray analysis revealed the formation of metal particles in the treated metal solutions. In addition to heavy metals at variable ratios, these particles consisted of carbon, oxygen, sulfur, nitrogen elements. The inhibition of metal toxicity was attributed to the existence of ammonia, hydrogen sulfide, and carbon dioxide in the VMPs of E. coli Z3 culture that might responsible for the transformation of soluble metal ions into metal complexes. This study clarified the capability of E. coli Z3 for indirect detoxification of heavy metals via the immobilization of metal ions into biologically unavailable species. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biolistic- and Agrobacterium-mediated transformation protocols for wheat.

PubMed

Tamás-Nyitrai, Cecília; Jones, Huw D; Tamás, László

2012-01-01

After rice, wheat is considered to be the most important world food crop, and the demand for high-quality wheat flour is increasing. Although there are no GM varieties currently grown, wheat is an important target for biotechnology, and we anticipate that GM wheat will be commercially available in 10-15 years. In this chapter, we summarize the main features and challenges of wheat transformation and then describe detailed protocols for the production of transgenic wheat plants both by biolistic and Agrobacterium-mediated DNA-delivery. Although these methods are used mainly for bread wheat (Triticum aestivum L.), they can also be successfully applied, with slight modifications, to tetraploid durum wheat (T. turgidum L. var. durum). The appropriate size and developmental stage of explants (immature embryo-derived scutella), the conditions to produce embryogenic callus tissues, and the methods to regenerate transgenic plants under increasing selection pressure are provided in the protocol. To illustrate the application of herbicide selection system, we have chosen to describe the use of the plasmid pAHC25 for biolistic transformation, while for Agrobacterium-mediated transformation the binary vector pAL156 (incorporating both the bar gene and the uidA gene) has been chosen. Beside the step-by-step methodology for obtaining stably transformed and normal fertile plants, procedures for screening and testing transgenic wheat plants are also discussed.

Transformational leadership, empowerment, and job satisfaction: the mediating role of employee empowerment.

PubMed

Choi, Sang Long; Goh, Chin Fei; Adam, Muhammad Badrull Hisyam; Tan, Owee Kowang

2016-12-01

Recent studies have revealed that nursing staff turnover remains a major problem in emerging economies. In particular, nursing staff turnover in Malaysia remains high due to a lack of job satisfaction. Despite a shortage of healthcare staff, the Malaysian government plans to create 181 000 new healthcare jobs by 2020 through the Economic Transformation Programme (ETP). This study investigated the causal relationships among perceived transformational leadership, empowerment, and job satisfaction among nurses and medical assistants in two selected large private and public hospitals in Malaysia. This study also explored the mediating effect of empowerment between transformational leadership and job satisfaction. This study used a survey to collect data from 200 nursing staff, i.e., nurses and medical assistants, employed by a large private hospital and a public hospital in Malaysia. Respondents were asked to answer 5-point Likert scale questions regarding transformational leadership, employee empowerment, and job satisfaction. Partial least squares-structural equation modeling (PLS-SEM) was used to analyze the measurement models and to estimate parameters in a path model. Statistical analysis was performed to examine whether empowerment mediated the relationship between transformational leadership and job satisfaction. This analysis showed that empowerment mediated the effect of transformational leadership on the job satisfaction in nursing staff. Employee empowerment not only is indispensable for enhancing job satisfaction but also mediates the relationship between transformational leadership and job satisfaction among nursing staff. The results of this research contribute to the literature on job satisfaction in healthcare industries by enhancing the understanding of the influences of empowerment and transformational leadership on job satisfaction among nursing staff. This study offers important policy insight for healthcare managers who seek to increase job

Agrobacterium tumefaciens-mediated transformation of oleaginous yeast Lipomyces species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Ziyu; Deng, Shuang; Culley, David E.

Background: Because of interest in the production of renewable bio-hydrocarbon fuels, various living organisms have been explored for their potential use in producing fuels and chemicals. The oil-producing (oleaginous) yeast Lipomyces starkeyi is the subject of active research regarding the production of lipids using a wide variety of carbon and nutrient sources. The genome of L. starkeyi has been published, which opens the door to production strain improvements using the tools of synthetic biology and metabolic engineering. However, using these tools for strain improvement requires the establishment of effective and reliable transformation methods with suitable selectable markers (antibiotic resistance ormore » auxotrophic marker genes) and the necessary genetic elements (promoters and terminators) for expression of introduced genes. Chemical-based methods have been published, but suffer from low efficiency or the requirement for targeting to rRNA loci. To address these problems, Agrobacterium-mediated transformation was investigated as an alternative method for L. starkeyi and other Lipomyces species. Results: In this study, Agrobacterium-mediated transformation was demonstrated to be effective in the transformation of both L. starkeyi and other Lipomyces species and that the introduced DNA can be reliably integrated into the chromosomes of these species. The gene deletion of Ku70 and Pex10 was also demonstrated in L. starkeyi. In addition to the bacterial antibiotic selection marker gene hygromycin B phosphotransferase, the bacterial -glucuronidase reporter gene under the control of L. starkeyi translation elongation factor 1 promoter was also stably expressed in seven different Lipomyces species. Conclusion: The results from this study clearly demonstrate that Agrobacterium-mediated transformation is a reliable genetic tool for gene deletion and integration and expression of heterologous genes in L. starkeyi and other Lipomyces species.« less

Modeling of Heavy Metal Transformation in Soil Ecosystem

NASA Astrophysics Data System (ADS)

Kalinichenko, Kira; Nikovskaya, Galina N.

2017-04-01

The intensification of industrial activity leads to an increase in heavy metals pollution of soils. In our opinion, sludge from biological treatment of municipal waste water, stabilized under aerobic-anaerobic conditions (commonly known as biosolid), may be considered as concentrate of natural soil. In their chemical, physical and chemical and biological properties these systems are similar gel-like nanocomposites. These contain microorganisms, humic substances, clay, clusters of nanoparticles of heavy metal compounds, and so on involved into heteropolysaccharides matrix. It is known that microorganisms play an important role in the transformation of different nature substances in soil and its health maintenance. The regularities of transformation of heavy metal compounds in soil ecosystem were studied at the model of biosolid. At biosolid swelling its structure changing (gel-sol transition, weakening of coagulation contacts between metal containing nanoparticles, microbial cells and metabolites, loosening and even destroying of the nanocomposite structure) can occur [1, 2]. The promotion of the sludge heterotrophic microbial activities leads to solubilization of heavy metal compounds in the system. The microbiological process can be realized in alcaligeneous or acidogeneous regimes in dependence on the type of carbon source and followed by the synthesis of metabolites with the properties of flocculants and heavy metals extragents [3]. In this case the heavy metals solubilization (bioleaching) in the form of nanoparticles of hydroxycarbonate complexes or water soluble complexes with oxycarbonic acids is observed. Under the action of biosolid microorganisms the heavy metals-oxycarbonic acids complexes can be transformed (catabolised) into nano-sizing heavy metals- hydroxycarbonates complexes. These ecologically friendly complexes and microbial heteropolysaccharides are able to interact with soil colloids, stay in the top soil profile, and improve soil structure due

Regulatory focus and burnout in nurses: The mediating effect of perception of transformational leadership.

PubMed

Shi, Rui; Zhang, Shilei; Xu, Hang; Liu, Xufeng; Miao, Danmin

2015-12-01

This correlation study investigated the relationship between nurses' regulatory focus and burnout, as mediated by their perceptions of transformational leadership, using a cross-sectional research design with anonymous questionnaires. In July-August 2012, data were collected from 378 nurses from three hospitals in Shaanxi Province, China, using self-report questionnaires for measuring the nurses' regulatory focus, their level of burnout and their perception of whether the leadership of their supervisor was transformational. Structural equation modelling and bootstrapping procedures were used to identify the mediating effect of their perceptions of transformational leadership. The results supported our hypothesized model. The type of regulatory focus emerged as a significant predictor of burnout. Having a perception of transformational leadership partially mediated the relationship between regulatory focus and burnout. Having a promotion focus reduced burnout when the participants perceived transformational leadership, whereas having a prevention focus exhibited the opposite pattern. The mediating effect of the perception of transformational leadership suggests that a promotion focus may help diminish burnout, directly and indirectly. Nurse managers must be aware of the role of a regulatory focus and cultivate promotion focus in their followers. © 2014 Wiley Publishing Asia Pty Ltd.

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process.

PubMed

Feng, Bingmei; Wang, Huixin; Wang, Dongniu; Yu, Huilong; Chu, Yi; Fang, Hai-Tao

2014-11-06

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO₂ coated-carbon nanotube (CNT), SnO₂ coated-CNT, Cu₂O/CuO coated-CNT and TiO₂ coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO₂-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO₂ coated-carboxylated CNTs and TiO₂-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO₂ coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO₂ of the former reaches 85 mA h g(-1), twice as high as that of the latter.

Selective Metal Cation Capture by Soft Anionic Metal-Organic Frameworks via Drastic Single-Crystal-to-Single-Crystal Transformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Jian; Saraf, Laxmikant V.; Schwenzer, Birgit

2012-05-25

Flexible anionic metal-organic frameworks transform to neutral heterobimetallic systems via single-crystal-to-single-crystal processes invoked by cation insertion. These transformations are directed by cooperative bond breakage and formation, resulting in expansion or contraction of the 3D framework by up to 33% due to the flexible nature of the organic linker. These MOFs displays highly selective uptake of divalent transition metal cations (Co2+ and Ni2+ for example) over alkali metal cations (Li+ and Na+).

Agrobacterium-mediated genetic transformation of Fraxinus americana hypocotyls

Treesearch

Kaitlin J. Palla; Paula M. Pijut

2015-01-01

An Agrobacterium tumefaciens-mediated genetic transformation system was successfully developed for white ash (Fraxinus americana) using hypocotyls as the initial explants. Hypocotyls isolated from mature embryos germinated on Murashige and Skoog (MS) medium supplemented with 22.2 µM 6-benzyladenine (BA) and 0.5 µM...

Microbial-mediated method for metal oxide nanoparticle formation

DOEpatents

Rondinone, Adam J.; Moon, Ji Won; Love, Lonnie J.; Yeary, Lucas W.; Phelps, Tommy J.

2015-09-08

The invention is directed to a method for producing metal oxide nanoparticles, the method comprising: (i) subjecting a combination of reaction components to conditions conducive to microbial-mediated formation of metal oxide nanoparticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium suitable for sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible metal oxide component containing one or more reducible metal species, and one or more electron donors that provide donatable electrons to said metal-reducing microbes during consumption of the electron donor by said metal-reducing microbes; and (ii) isolating said metal oxide nanoparticles, which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide nanoparticle compositions produced by the inventive method.

Agrobacterium- and Biolistic-Mediated Transformation of Maize B104 Inbred.

PubMed

Raji, Jennifer A; Frame, Bronwyn; Little, Daniel; Santoso, Tri Joko; Wang, Kan

2018-01-01

Genetic transformation of maize inbred genotypes remains non-routine for many laboratories due to variations in cell competency to induce embryogenic callus, as well as the cell's ability to receive and incorporate transgenes into the genome. This chapter describes two transformation protocols using Agrobacterium- and biolistic-mediated methods for gene delivery. Immature zygotic embryos of maize inbred B104, excised from ears harvested 10-14 days post pollination, are used as starting explant material. Disarmed Agrobacterium strains harboring standard binary vectors and the biolistic gun system Bio-Rad PDS-1000/He are used as gene delivery systems. The herbicide resistant bar gene and selection agent bialaphos are used for identifying putative transgenic type I callus events. Using the step-by-step protocols described here, average transformation frequencies (number of bialaphos resistant T 0 callus events per 100 explants infected or bombarded) of 4% and 8% can be achieved using the Agrobacterium- and biolistic-mediated methods, respectively. An estimated duration of 16-21 weeks is needed using either protocol from the start of transformation experiments to obtaining putative transgenic plantlets with established roots. In addition to laboratory in vitro procedures, detailed greenhouse protocols for producing immature ears as transformation starting material and caring for transgenic plants for seed production are also described.

Electrochemically Induced Insulator-Metal-Insulator Transformations of Vanadium Dioxide Nanocrystal Films

NASA Astrophysics Data System (ADS)

Milliron, Delia; Dahlman, Clayton; Leblanc, Gabriel; Bergerud, Amy

Vanadium dioxide (VO2) undergoes significant optical, electronic, and structural changes as it transforms between the low-temperature monoclinic and high-temperature rutile phases. The low-temperature state is insulating and transparent, while the high-temperature state is metallic and IR blocking. Alternative stimuli have been utilized to trigger insulator-to-metal transformations in VO2, including electrochemical gating. Here, VO2 nanocrystal films have been prepared by solution deposition of V2O3 nanocrystals followed by oxidative annealing. Nanocrystalline VO2 films are electrochemically reduced, inducing changes in their electronic and optical properties. We observe a reversible transition between infrared transparent insulating phases and a darkened metallic phase by in situ visible-near-infrared spectroelectrochemistry and correlate these observations with structural and electronic changes monitored by X-ray absorption spectroscopy, X-ray diffraction, Raman spectroscopy, and conductivity measurements. Reduction causes an initial transformation to a metallic, IR-colored distorted monoclinic phase. However, an unexpected reversible transition from conductive, reduced monoclinic VO2 to an infrared-transparent insulating phase is observed upon further reduction.

Transformation of heavy metal speciation during sludge drying: mechanistic insights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weng, Huanxin; Ma, Xue-Wen; Fu, Feng-Xia

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized the Cr, Cu, Cd and Pb in sludge by transforming acid-soluble, reducible andmore » oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge.« less

Transformation of heavy metal speciation during sludge drying: mechanistic insights.

PubMed

Weng, Huan-Xin; Ma, Xue-Wen; Fu, Feng-Xia; Zhang, Jin-Jun; Liu, Zan; Tian, Li-Xun; Liu, Chongxuan

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized Cr, Cu, Cd, and Pb in sludge by transforming acid-soluble, reducible, and oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge. Copyright © 2013 Elsevier B.V. All rights reserved.

Lysosome-related organelles as mediators of metal homeostasis.

PubMed

Blaby-Haas, Crysten E; Merchant, Sabeeha S

2014-10-10

Metal ion assimilation is essential for all forms of life. However, organisms must properly control the availability of these nutrients within the cell to avoid inactivating proteins by mismetallation. To safeguard against an imbalance between supply and demand in eukaryotes, intracellular compartments contain metal transporters that load and unload metals. Although the vacuoles of Saccharomyces cerevisiae and Arabidopsis thaliana are well established locales for the storage of copper, zinc, iron, and manganese, related compartments are emerging as important mediators of metal homeostasis. Here we describe these compartments and review their metal transporter complement. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Metal oxide nanoparticle mediated enhanced Raman scattering and its use in direct monitoring of interfacial chemical reactions.

PubMed

Li, Li; Hutter, Tanya; Finnemore, Alexander S; Huang, Fu Min; Baumberg, Jeremy J; Elliott, Stephen R; Steiner, Ullrich; Mahajan, Sumeet

2012-08-08

Metal oxide nanoparticles (MONPs) have widespread usage across many disciplines, but monitoring molecular processes at their surfaces in situ has not been possible. Here we demonstrate that MONPs give highly enhanced (×10(4)) Raman scattering signals from molecules at the interface permitting direct monitoring of their reactions, when placed on top of flat metallic surfaces. Experiments with different metal oxide materials and molecules indicate that the enhancement is generic and operates at the single nanoparticle level. Simulations confirm that the amplification is principally electromagnetic and is a result of optical modulation of the underlying plasmonic metallic surface by MONPs, which act as scattering antennae and couple light into the confined region sandwiched by the underlying surface. Because of additional functionalities of metal oxides as magnetic, photoelectrochemical and catalytic materials, enhanced Raman scattering mediated by MONPs opens up significant opportunities in fundamental science, allowing direct tracking and understanding of application-specific transformations at such interfaces. We show a first example by monitoring the MONP-assisted photocatalytic decomposition reaction of an organic dye by individual nanoparticles.

Efficient transformation of oil palm protoplasts by PEG-mediated transfection and DNA microinjection.

PubMed

Masani, Mat Yunus Abdul; Noll, Gundula A; Parveez, Ghulam Kadir Ahmad; Sambanthamurthi, Ravigadevi; Prüfer, Dirk

2014-01-01

Genetic engineering remains a major challenge in oil palm (Elaeis guineensis) because particle bombardment and Agrobacterium-mediated transformation are laborious and/or inefficient in this species, often producing chimeric plants and escapes. Protoplasts are beneficial as a starting material for genetic engineering because they are totipotent, and chimeras are avoided by regenerating transgenic plants from single cells. Novel approaches for the transformation of oil palm protoplasts could therefore offer a new and efficient strategy for the development of transgenic oil palm plants. We recently achieved the regeneration of healthy and fertile oil palms from protoplasts. Therefore, we focused on the development of a reliable PEG-mediated transformation protocol for oil palm protoplasts by establishing and validating optimal heat shock conditions, concentrations of DNA, PEG and magnesium chloride, and the transfection procedure. We also investigated the transformation of oil palm protoplasts by DNA microinjection and successfully regenerated transgenic microcalli expressing green fluorescent protein as a visible marker to determine the efficiency of transformation. We have established the first successful protocols for the transformation of oil palm protoplasts by PEG-mediated transfection and DNA microinjection. These novel protocols allow the rapid and efficient generation of non-chimeric transgenic callus and represent a significant milestone in the use of protoplasts as a starting material for the development of genetically-engineered oil palm plants.

An improved Agrobacterium-mediated transformation of recalcitrant indica rice (Oryza sativa L.) cultivars.

PubMed

Shri, Manju; Rai, Arti; Verma, Pankaj Kumar; Misra, Prashant; Dubey, Sonali; Kumar, Smita; Verma, Sikha; Gautam, Neelam; Tripathi, Rudra Deo; Trivedi, Prabodh Kumar; Chakrabarty, Debasis

2013-04-01

Agrobacterium-mediated transformation of indica rice varieties has been quite difficult as these are recalcitrant to in vitro responses. In the present study, we established a high-efficiency Agrobacterium tumefaciens-mediated transformation system of rice (Oryza sativa L. ssp. indica) cv. IR-64, Lalat, and IET-4786. Agrobacterium strain EHA-101 harboring binary vector pIG121-Hm, containing a gene encoding for β-glucuronidase (GUS) and hygromycin resistance, was used in the transformation experiments. Manipulation of different concentrations of acetosyringone, days of co-culture period, bacterial suspension of different optical densities (ODs), and the concentrations of L-cysteine in liquid followed by solid co-culture medium was done for establishing the protocol. Among the different co-culture periods, 5 days of co-culture with bacterial cells (OD600 nm = 0.5-0.8) promoted the highest frequency of transformation (83.04 %) in medium containing L-cysteine (400 mg l(-1)). Putative transformed plants were analyzed for the presence of a transgene through genomic PCR and GUS histochemical analyses. Our results also suggest that different cultural conditions and the addition of L-cysteine in the co-culture medium improve the Agrobacterium-mediated transformation frequencies from an average of 12.82 % to 33.33 % in different indica rice cultivars.

Efficient Transformation of Oil Palm Protoplasts by PEG-Mediated Transfection and DNA Microinjection

PubMed Central

Masani, Mat Yunus Abdul; Noll, Gundula A.; Parveez, Ghulam Kadir Ahmad; Sambanthamurthi, Ravigadevi; Prüfer, Dirk

2014-01-01

Background Genetic engineering remains a major challenge in oil palm (Elaeis guineensis) because particle bombardment and Agrobacterium-mediated transformation are laborious and/or inefficient in this species, often producing chimeric plants and escapes. Protoplasts are beneficial as a starting material for genetic engineering because they are totipotent, and chimeras are avoided by regenerating transgenic plants from single cells. Novel approaches for the transformation of oil palm protoplasts could therefore offer a new and efficient strategy for the development of transgenic oil palm plants. Methodology/Principal Findings We recently achieved the regeneration of healthy and fertile oil palms from protoplasts. Therefore, we focused on the development of a reliable PEG-mediated transformation protocol for oil palm protoplasts by establishing and validating optimal heat shock conditions, concentrations of DNA, PEG and magnesium chloride, and the transfection procedure. We also investigated the transformation of oil palm protoplasts by DNA microinjection and successfully regenerated transgenic microcalli expressing green fluorescent protein as a visible marker to determine the efficiency of transformation. Conclusions/Significance We have established the first successful protocols for the transformation of oil palm protoplasts by PEG-mediated transfection and DNA microinjection. These novel protocols allow the rapid and efficient generation of non-chimeric transgenic callus and represent a significant milestone in the use of protoplasts as a starting material for the development of genetically-engineered oil palm plants. PMID:24821306

Phase transformations in the hematite-metal system during mechanical alloying

NASA Astrophysics Data System (ADS)

Kozlov, K. A.; Shabashov, V. A.; Litvinov, A. V.; Sagaradze, V. V.

2009-04-01

Mössbauer spectroscopy and X-ray diffraction are used to show that the phase transformations in hematite α-Fe2O3-metal ( M = Fe, Ni, Ti, Zr) powder mixtures induced by severe cold plastic deformation in ball mills occur via the formation of M-Fe-O solid solutions, redox reactions with the reduction of metallic iron, and the formation of secondary M x O y oxides and M x Fe y intermetallics. Mechanical activation in a ball mill is compared to that under high-pressure shear in Bridgman anvils. The transformations that take place in a ball mill are found to have several stages and to be accelerated.

Frugivore-Mediated Selection in A Habitat Transformation Scenario

PubMed Central

Fontúrbel, Francisco E.; Medel, Rodrigo

2017-01-01

Plant-animal interactions are strong drivers of phenotypic evolution. However, the extent to which anthropogenic habitat transformation creates new selective scenarios for plant-animal interactions is a little explored subject. We examined the effects of native forest replacement by exotic Eucalyptus trees on the frugivore-mediated phenotypic selection coefficients imposed by the relict marsupial Dromiciops gliroides upon traits involved in frugivore attraction and germination success of the mistletoe Tristerix corymbosus (Loranthaceae). We found significant gradients for seed weight and sugar content along the native - transformed habitat gradient. While selection for larger seed weight was more relevant in native habitats, fruits with intermediate sugar content were promoted in transformed habitats. The spatial habitat structure and microclimate features such as the degree of sunlight received influenced the natural selection processes, as they correlated with the phenotypic traits analysed. The response of this plant-frugivore interaction to human disturbance seemed to be context-dependent, in which extremely transformed habitats would offer new opportunities for natural selection on dispersal-related traits. Even in recent transformation events like this, human disturbance acts as a strong contemporary evolution driver. PMID:28349942

Advances in Agrobacterium tumefaciens-mediated genetic transformation of graminaceous crops.

PubMed

Singh, Roshan Kumar; Prasad, Manoj

2016-05-01

Steady increase in global population poses several challenges to plant science research, including demand for increased crop productivity, grain yield, nutritional quality and improved tolerance to different environmental factors. Transgene-based approaches are promising to address these challenges by transferring potential candidate genes to host organisms through different strategies. Agrobacterium-mediated gene transfer is one such strategy which is well known for enabling efficient gene transfer in both monocot and dicots. Due to its versatility, this technique underwent several advancements including development of improved in vitro plant regeneration system, co-cultivation and selection methods, and use of hyper-virulent strains of Agrobacterium tumefaciens harbouring super-binary vectors. The efficiency of this method has also been enhanced by the use of acetosyringone to induce the activity of vir genes, silver nitrate to reduce the Agrobacterium-induced necrosis and cysteine to avoid callus browning during co-cultivation. In the last two decades, extensive efforts have been invested towards achieving efficient Agrobacterium-mediated transformation in cereals. Though high-efficiency transformation systems have been developed for rice and maize, comparatively lesser progress has been reported in other graminaceous crops. In this context, the present review discusses the progress made in Agrobacterium-mediated transformation system in rice, maize, wheat, barley, sorghum, sugarcane, Brachypodium, millets, bioenergy and forage and turf grasses. In addition, it also provides an overview of the genes that have been recently transferred to these graminaceous crops using Agrobacterium, bottlenecks in this technique and future possibilities for crop improvement.

Metal-Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal-Organic Framework.

PubMed

Cliffe, Matthew J; Castillo-Martínez, Elizabeth; Wu, Yue; Lee, Jeongjae; Forse, Alexander C; Firth, Francesca C N; Moghadam, Peyman Z; Fairen-Jimenez, David; Gaultois, Michael W; Hill, Joshua A; Magdysyuk, Oxana V; Slater, Ben; Goodwin, Andrew L; Grey, Clare P

2017-04-19

We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed "double cluster" (Hf 12 O 8 (OH) 14 ), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal-organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal-organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials.

Dioxygen in Polyoxometalate Mediated Reactions.

PubMed

Weinstock, Ira A; Schreiber, Roy E; Neumann, Ronny

2018-03-14

In this review article, we consider the use of molecular oxygen in reactions mediated by polyoxometalates. Polyoxometalates are anionic metal oxide clusters of a variety of structures that are soluble in liquid phases and therefore amenable to homogeneous catalytic transformations. Often, they are active for electron transfer oxidations of a myriad of substrates and upon reduction can be reoxidized by molecular oxygen. For example, the phosphovanadomolybdate, H 5 PV 2 Mo 10 O 40 , can oxidize Pd(0) thereby enabling aerobic reactions catalyzed by Pd and H 5 PV 2 Mo 10 O 40 . In a similar vein, polyoxometalates can stabilize metal nanoparticles, leading to additional transformations. Furthermore, electron transfer oxidation of other substrates such as halides and sulfur-containing compounds is possible. More uniquely, H 5 PV 2 Mo 10 O 40 and its analogues can mediate electron transfer-oxygen transfer reactions where oxygen atoms are transferred from the polyoxometalate to the substrate. This unique property has enabled correspondingly unique transformations involving carbon-carbon, carbon-hydrogen, and carbon-metal bond activation. The pathway for the reoxidation of vanadomolybdates with O 2 appears to be an inner-sphere reaction, but the oxidation of one-electron reduced polyoxotungstates has been shown through intensive research to be an outer-sphere reaction. Beyond electron transfer and electron transfer-oxygen transfer aerobic transformations, there a few examples of apparent dioxygenase activity where both oxygen atoms are donated to a substrate.

Agrobacterium-mediated transformation of finger millet (Eleusine coracana (L.) Gaertn.) using shoot apex explants.

PubMed

Ceasar, S Antony; Ignacimuthu, S

2011-09-01

A new Agrobacterium-mediated transformation system was developed for finger millet using shoot apex explants. The Agrobacterium strain LBA4404 harboring binary vector pCAMBIA1301, which contained hygromycin phosphotransferase (hptII) as selectable marker gene and β-glucuronidase (GUS) as reporter gene, was used for optimization of transformation conditions. Two finger millet genotypes, GPU 45 and CO 14, were used in this study. The optimal conditions for the Agrobacterium-mediated transformation of finger millet were found to be the co-cultivation of explants obtained on the 16th day after callus induction (DACI), exposure of explants for 30 min to agrobacterial inoculum and 3 days of co-cultivation on filter paper placed on medium supplemented with 100 μM acetosyringone (AS). Addition of 100 μM L: -cysteine in the selection medium enhanced the frequency of transformation and transgenic plant recovery. Both finger millet genotypes were transformed by Agrobacterium. A frequency of 19% transient expression with 3.8% stable transformation was achieved in genotype GPU 45 using optimal conditions. Five stably transformed plants were fully characterized by Southern blot analysis. A segregation analysis was also performed in four R(1) progenies, which showed normal Mendelian pattern of transgene segregation. The inheritance of transgenes in R(1) progenies was also confirmed by Southern blot analysis. This is the first report on Agrobacterium-mediated transformation of finger millet. This study underpins the introduction of numerous agronomically important genes into the genome of finger millet in the future.

Highly Efficient Electroporation-mediated Transformation into Edible Mushroom Flammulina velutipes

PubMed Central

Kim, Jong Kun; Park, Young Jin; Kong, Won Sik

2010-01-01

In this study, we developed an efficient electroporation-mediated transformation system featuring Flammulina velutipes. The flammutoxin (ftx) gene of F. velutipes was isolated by reverse transcription-PCR. pFTXHg plasmid was constructed using the partial ftx gene (410 bp) along with the hygromycin B phosphotransferase gene (hygB) downstream of the glyceraldehydes-3-phosphate dehydrogenase (gpd) promoter. The plasmid was transformed into protoplasts of monokaryotic strain 4019-20 of F. velutipes by electroporation. High transformation efficiency was obtained with an electric-pulse of 1.25 kV/cm by using 177 transformants/µg of DNA in 1 × 107 protoplasts. PCR and Southern blot hybridization indicated that a single copy of the plasmid DNA was inserted at different locations in the F. velutipes genome by non-homologous recombination. Therefore, this transformation system could be used as a useful tool for gene function analysis of F. velutipes. PMID:23956676

Highly Efficient Electroporation-mediated Transformation into Edible Mushroom Flammulina velutipes.

PubMed

Kim, Jong Kun; Park, Young Jin; Kong, Won Sik; Kang, Hee Wan

2010-12-01

In this study, we developed an efficient electroporation-mediated transformation system featuring Flammulina velutipes. The flammutoxin (ftx) gene of F. velutipes was isolated by reverse transcription-PCR. pFTXHg plasmid was constructed using the partial ftx gene (410 bp) along with the hygromycin B phosphotransferase gene (hygB) downstream of the glyceraldehydes-3-phosphate dehydrogenase (gpd) promoter. The plasmid was transformed into protoplasts of monokaryotic strain 4019-20 of F. velutipes by electroporation. High transformation efficiency was obtained with an electric-pulse of 1.25 kV/cm by using 177 transformants/µg of DNA in 1 × 10(7) protoplasts. PCR and Southern blot hybridization indicated that a single copy of the plasmid DNA was inserted at different locations in the F. velutipes genome by non-homologous recombination. Therefore, this transformation system could be used as a useful tool for gene function analysis of F. velutipes.

Highly efficient transformation system for Malassezia furfur and Malassezia pachydermatis using Agrobacterium tumefaciens-mediated transformation.

PubMed

Celis, A M; Vos, A M; Triana, S; Medina, C A; Escobar, N; Restrepo, S; Wösten, H A B; de Cock, H

2017-03-01

Malassezia spp. are part of the normal human and animal mycobiota but are also associated with a variety of dermatological diseases. The absence of a transformation system hampered studies to reveal mechanisms underlying the switch from the non-pathogenic to pathogenic life style. Here we describe, a highly efficient Agrobacterium-mediated genetic transformation system for Malassezia furfur and M. pachydermatis. A binary T-DNA vector with the hygromycin B phosphotransferase (hpt) selection marker and the green fluorescent protein gene (gfp) was introduced in M. furfur and M. pachydermatis by combining the transformation protocols of Agaricus bisporus and Cryptococcus neoformans. Optimal temperature and co-cultivation time for transformation were 5 and 7days at 19°C and 24°C, respectively. Transformation efficiency was 0.75-1.5% for M. furfur and 0.6-7.5% for M. pachydermatis. Integration of the hpt resistance cassette and gfp was verified using PCR and fluorescence microscopy, respectively. The T-DNA was mitotically stable in approximately 80% of the transformants after 10 times sub-culturing in the absence of hygromycin. Improving transformation protocols contribute to study the biology and pathophysiology of Malassezia. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Transformational leadership, intrinsic motivation, and trust: a moderated-mediated model of workplace safety.

PubMed

Conchie, Stacey M

2013-04-01

Two studies examine the role of motivation and trust in the relationship between safety-specific transformational leadership and employees' safety behavior. Study 1 tested the prediction that intrinsic and identified regulation motivations mediate the relationship between safety-specific transformational leadership and employees' safety behaviors. Study 2 further explored this relationship by testing the prediction that the mediating role of intrinsic motivation is dependent on employees' level of trust in their leader. Survey data from the U.K. construction industry supported both predictions. However, the mediating role of intrinsic motivation was found only for challenge safety citizenship behaviors (i.e., voice) and not for affiliative safety citizenship behaviors (i.e., helping). These findings suggest that employees' intrinsic motivation is important to the effectiveness of leaders' efforts to promote some but not all forms of safety behavior.

Structural Transformation of Guanine Coordination Motifs in Water Induced by Metal ions and Temperature.

PubMed

Li, Wei; Jin, Jing; Liu, Xiaoqing; Wang, Li

2018-06-15

The transformation effects of metal ions and temperature on the DNA bases guanine (G) metal-organic coordination motifs in water have been investigated by scanning tunneling microcopy (STM). The G molecules form an ordered hydrogen-bonded structure at the water- highly oriented pyrolytic graphite (HOPG) interface. The STM observations reveal that the canonical G/9H form can be transformed into the G/(3H, 7H) tautomer by increasing the temperature of the G solution to 38.6oC. Moreover, metal ions bind with G molecules to form G4Fe13+, G3Fe32+ and the heterochiral intermixed G4Na1+ metal-organic networks after the introduction of the alkali-metal ions in cellular environment.

Establishment of a simple and efficient Agrobacterium-mediated transformation system for Phytophthora palmivora.

PubMed

Wu, Dongliang; Navet, Natasha; Liu, Yingchao; Uchida, Janice; Tian, Miaoying

2016-09-06

As an agriculturally important oomycete genus, Phytophthora contains a large number of destructive plant pathogens that severely threaten agricultural production and natural ecosystems. Among them is the broad host range pathogen P. palmivora, which infects many economically important plant species. An essential way to dissect their pathogenesis mechanisms is genetic modification of candidate genes, which requires effective transformation systems. Four methods were developed for transformation of Phytophthora spp., including PEG(polyethylene glycol)/CaCl2 mediated protoplast transformation, electroporation of zoospores, microprojectile bombardment and Agrobacterium-mediated transformation (AMT). Among them, AMT has many advantages over the other methods such as easy handling and mainly generating single-copy integration in the genome. An AMT method previously reported for P. infestans and P. palmivora has barely been used in oomycete research due to low success and low reproducibility. In this study, we report a simple and efficient AMT system for P. palmivora. Using this system, we were able to reproducibly generate over 40 transformants using zoospores collected from culture grown in a single 100 mm-diameter petri dish. The generated GFP transformants constitutively expressed GFP readily detectable using a fluorescence microscope. All of the transformants tested using Southern blot analysis contained a single-copy T-DNA insertion. This system is highly effective and reproducible for transformation of P. palmivora and expected to be adaptable for transformation of additional Phytophthora spp. and other oomycetes. Its establishment will greatly accelerate their functional genomic studies.

Agrobacterium rhizogenes-mediated transformation of Superroot-derived Lotus corniculatus plants: a valuable tool for functional genomics.

PubMed

Jian, Bo; Hou, Wensheng; Wu, Cunxiang; Liu, Bin; Liu, Wei; Song, Shikui; Bi, Yurong; Han, Tianfu

2009-06-25

Transgenic approaches provide a powerful tool for gene function investigations in plants. However, some legumes are still recalcitrant to current transformation technologies, limiting the extent to which functional genomic studies can be performed on. Superroot of Lotus corniculatus is a continuous root cloning system allowing direct somatic embryogenesis and mass regeneration of plants. Recently, a technique to obtain transgenic L. corniculatus plants from Superroot-derived leaves through A. tumefaciens-mediated transformation was described. However, transformation efficiency was low and it took about six months from gene transfer to PCR identification. In the present study, we developed an A. rhizogenes-mediated transformation of Superroot-derived L. corniculatus for gene function investigation, combining the efficient A. rhizogenes-mediated transformation and the rapid regeneration system of Superroot. The transformation system using A. rhizogenes K599 harbouring pGFPGUSPlus was improved by validating some parameters which may influence the transformation frequency. Using stem sections with one node as explants, a 2-day pre-culture of explants, infection with K599 at OD(600) = 0.6, and co-cultivation on medium (pH 5.4) at 22 degrees C for 2 days enhanced the transformation frequency significantly. As proof of concept, Superroot-derived L. corniculatus was transformed with a gene from wheat encoding an Na+/H+ antiporter (TaNHX2) using the described system. Transgenic Superroot plants were obtained and had increased salt tolerance, as expected from the expression of TaNHX2. A rapid and efficient tool for gene function investigation in L. corniculatus was developed, combining the simplicity and high efficiency of the Superroot regeneration system and the availability of A. rhizogenes-mediated transformation. This system was improved by validating some parameters influencing the transformation frequency, which could reach 92% based on GUS detection. The combination

From Nanowires to Biofilms: An Exploration of Novel Mechanisms of Uranium Transformation Mediated by Geobacter Bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

REGUERA, GEMMA

2014-01-16

One promising strategy for the in situ bioremediation of radioactive groundwater contaminants that has been identified by the SBR Program is to stimulate the activity of dissimilatory metal-reducing microorganisms to reductively precipitate uranium and other soluble toxic metals. The reduction of U(VI) and other soluble contaminants by Geobacteraceae is directly dependent on the reduction of Fe(III) oxides, their natural electron acceptor, a process that requires the expression of Geobacter’s conductive pili (pilus nanowires). Expression of conductive pili by Geobacter cells leads to biofilm development on surfaces and to the formation of suspended biogranules, which may be physiological closer to biofilmsmore » than to planktonic cells. Biofilm development is often assumed in the subsurface, particularly at the matrix-well screen interface, but evidence of biofilms in the bulk aquifer matrix is scarce. Our preliminary results suggest, however, that biofilms develop in the subsurface and contribute to uranium transformations via sorption and reductive mechanisms. In this project we elucidated the mechanism(s) for uranium immobilization mediated by Geobacter biofilms and identified molecular markers to investigate if biofilm development is happening in the contaminated subsurface. The results provided novel insights needed in order to understand the metabolic potential and physiology of microorganisms with a known role in contaminant transformation in situ, thus having a significant positive impact in the SBR Program and providing novel concept to monitor, model, and predict biological behavior during in situ treatments.« less

Gene disruption in Trichoderma atroviride via Agrobacterium-mediated transformation.

PubMed

Zeilinger, Susanne

2004-02-01

A modified Agrobacterium-mediated transformation method for the efficient disruption of two genes encoding signaling compounds of the mycoparasite Trichoderma atroviride is described, using the hph gene of Escherichia coli as selection marker. The transformation vectors contained about 1 kb of 5' and 3' non-coding regions from the tmk1 (encoding a MAP kinase) or tga3 (encoding an alpha-subunit of a heterotrimeric G protein) target loci flanking a selection marker. Transformation of fungal conidia and selection on hygromycin-containing media applying an overlay-based procedure, which overcomes the lack of formation of distinct single colonies by the fungus, led to stable clones for both disruption constructs. Southern and PCR analyses proved gene disruption by single-copy homologous integration with a frequency of approximately 60% for both genes; and the loss of tmk1 and tga3 transcript formation in the disruptants was demonstrated by RT-PCR.

Reductive dechlorination of trichloroethene mediated by humic-metal complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

O`Loughlin, E.J.; Burris, D.R.; Delcomyn, C.A.

1999-04-01

Experiments were conducted to determine if transition metal-humic acid complexes can act as e{sup {minus}} transfer mediators in the reductive dechlorination of trichloroethene (TCE) using Ti(III) citrate as the bulk reductant. In the presence of Ni-Aldrich humic acid (AHA) complexes, TCE reduction was rapid, with complete removal of TCE in less than 23 h. Cu-AHA complexes were less effective as e{sup {minus}} mediators than Ni-AHA complexes; only 60% of TCE was reduced after 150 h. Partially dechlorinated intermediates were observed during TCE reduction; however, they were transitory, and at no time accounted for more than 2% of the initial TCEmore » mass on a mole C basis. Ethane and ethene were the primary end products of TCE reduction; however, a suite of other non-chlorinated hydrocarbons consisting of methane and C{sub 3} to C{sub 6} alkanes and alkenes were also observed. The results suggest that humic-metal complexes may represent a previously unrecognized class of electron mediators in natural environments.« less

Visible Light Induced Organic Transformations Using Metal-Organic-Frameworks (MOFs).

PubMed

Deng, Xiaoyu; Li, Zhaohui; García, Hermenegildo

2017-08-22

With the aim of developing renewable energy based processes, researchers are paying increasing interest to light induced organic transformations. Metal-organic frameworks (MOFs), a class of micro-/mesoporous hybrid materials, are recently emerging as a new type of photoactive materials for organic syntheses due to their unique structural characteristics. In this Review, we summarized the recent applications of MOFs as photocatalysts for light induced organic transformations, including (1) oxidation of alcohols, amines, alkene, alkanes and sulfides; (2) hydroxylation of aromatic compounds like benzene; (3) activation of the C-H bonds to construct new C-C or C-X bonds; (4) atom-transfer radical polymerization (ATRP). This Review starts with general background information of using MOFs in photocatalysis, followed by a description of light induced organic transformations promoted by photoactive inorganic nodes and photocatalytic active ligands in MOFs, respectively. Thereafter, the use of MOFs as multifunctional catalysts for light induced organic transformations via an efficient merge of the metal/ligand/guest based catalysis where the photocatalytic activity of MOFs plays a key role are discussed. Finally, the limitations, challenges and the future perspective of the application of MOFs for light induced organic transformations were addressed. The objective of this Review is to serve as a starting point for other researchers to get into this largely unexplored field. It is also our goal to stimulate intensive research in this field for rational designing of MOF materials to overcome their current limitations in photocatalysis, which can lead to more creative visible-light-induced organic transformations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Relationship between transformational leadership style and organizational commitment: Mediating effect of psychological empowerment

NASA Astrophysics Data System (ADS)

Asif, Muhammad; Ayyub, Samia; Bashir, Muhammad Khawar

2014-12-01

This study explores the relationship between style of transformational leadership and organizational commitment of employees with mediating role of psychological empowerment in the textile sector Punjab Pakistan. Data was collected using tools from 250 employees. The transformational leadership questionnaire, MLQ-Multifactor leadership Questionnaire [1] was used to verify the perception of the employees towards transformational leadership style in two dimensions i.e. idealized influence and inspirational motivation. The organizational commitment questionnaire designed by [2] was used to verify the affective organizational commitment. Further, psychological empowerment questionnaire was developed by [3] which was used to examine the state of psychological empowerment of textile sector employees. Pearson Correlation revealed that there exists a positive significant relationship between idealized influence and affective organizational commitment, Inspirational motivation and affective organizational commitment, affective organizational commitment and psychological empowerment. The results from the study put forward that there is a significant relationship between style of transformational leadership and organizational commitment. The mediating variable which one is suitable in the model i.e. psychological empowerment and the model is good fit as the F value is significant.

Agrobacterium-mediated genetic transformation and plant regeneration of the hardwood tree species Fraxinus profunda

Treesearch

Micah E. Stevens; Paula M. Pijut

2014-01-01

Using mature hypocotyls as the initial explants, an Agrobacterium tumefaciens-mediated genetic transformation system was successfully developed for pumpkin ash (Fraxinus profunda). This transformation protocol is an invaluable tool to combat the highly aggressive, non-native emerald ash borer (EAB), which has the potential to...

Optimization of Production Conditions for Protoplasts and Polyethylene Glycol-Mediated Transformation of Gaeumannomyces tritici.

PubMed

Wang, Mei; Zhang, Jie; Wang, Lanying; Han, Lirong; Zhang, Xing; Feng, Juntao

2018-05-24

Take-all, caused by Gaeumannomyces tritici , is one of the most important wheat root diseases worldwide, as it results in serious yield losses. In this study, G. tritici was transformed to express the hygromycin B phosphotransferase using a combined protoplast and polyethylene glycol (PEG)-mediated transformation technique. Based on a series of single-factor experimental results, three major factors-temperature, enzyme lysis time, and concentration of the lysing enzyme-were selected as the independent variables, which were optimized using the response surface methodology. A higher protoplast yield of 9.83 × 10⁷ protoplasts/mL was observed, and the protoplast vitality was also high, reaching 96.27% after optimization. Protoplasts were isolated under the optimal conditions, with the highest transformation frequency (46⁻54 transformants/μg DNA). Polymerase chain reaction and Southern blotting detection indicated that the genes of hygromycin phosphotransferase were successfully inserted into the genome of G. tritici . An optimised PEG-mediated protoplast transformation system for G. tritici was established. The techniques and procedures described will lay the foundation for establishing a good mutation library of G. tritici and could be used to transform other fungi.

Agrobacterium tumefaciens-mediated transformation of Phellodendron amurense Rupr. using mature-seed explants.

PubMed

Yang, Jingli; Zhao, Bo; Kim, Yeon Bok; Zhou, Chenguang; Li, Chunyan; Chen, Yunlin; Zhang, Haizhen; Li, Cheng Hao

2013-01-01

An efficient transformation protocol was developed for Agrobacterium-mediated transformation of Phellodendron amurense Rupr. for using explants from mature seeds. The binary vector pCAMBIA1303, which contained hygromycin phosphotransferase (hptII) as a selectable marker gene and β-glucuronidase (GUS) as a reporter gene, was used for transformation studies. Different factors that affect survival of transformed buds, namely Agrobacterium infection method, bacterial strain, pre-culture duration, acetosyringone concentration, co-culture duration, and co-culture temperature were examined and optimized for transformation efficiency on the basis of GUS staining of hygromycin-resistant buds. Polymerase chain reaction (PCR), Southern blot and reverse transcription PCR confirmed the presence of the GUS gene. A transformation frequency of 13.1 % was achieved under optimized conditions for transformation (A. tumefaciens strain EHA105, 4 days co-cultivation at 4 °C, and infection of the pre-cultured mature-seed explants for 2 days). This is the first report of a successful genetic transformation protocol for P. amurense.

Detection of defects in formed sheet metal using medial axis transformation

NASA Astrophysics Data System (ADS)

Murmu, Naresh C.; Velgan, Roman

2003-05-01

In the metal forming processes, the sheet metals are often prone to various defects such as thinning, dents, wrinkles etc. In the present manufacturing environments with ever increasing demand of higher quality, detecting the defects of formed sheet metal using an effective and objective inspection system is the foremost norm to remain competitive in market. The defect detection using optical techniques aspire to satisfy its needs to be non-contact and fast. However, the main difficulties to achieve this goal remain essentially on the development of efficient evaluation technique and accurate interpretation of extracted data. The defect like thinning is detected by evaluating the deviations of the thickness in the formed sheet metal against its nominal value. The present evaluation procedure for determination of thickness applied on the measurements data is not without deficiency. To improve this procedure, a new evaluation approach based on medial axis transformation is proposed here. The formed sheet metals are digitized using fringe projection systems in different orientations, and afterwards registered into one coordinate frame. The medial axis transformation (MAT) is applied on the point clouds, generating the point clouds of MAT. This data is further processed and medial surface is determined. The thinning defect is detected by evaluating local wall thickness and other defects like wrinkles are determined using the shape recognition on the medial surface. The applied algorithm is simple, fast and robust.

Progress of cereal transformation technology mediated by Agrobacterium tumefaciens.

PubMed

Hiei, Yukoh; Ishida, Yuji; Komari, Toshihiko

2014-01-01

Monocotyledonous plants were believed to be not transformable by the soil bacterium Agrobacterium tumefaciens until two decades ago, although convenient protocols for infection of leaf disks and subsequent regeneration of transgenic plants had been well established in a number of dicotyledonous species by then. This belief was reinforced by the fact that monocotyledons are mostly outside the host range of crown gall disease caused by the bacterium and by the failures in trials in monocotyledons to mimic the transformation protocols for dicotyledons. However, a key reason for the failure could have been the lack of active cell divisions at the wound sites in monocotyledons. The complexity and narrow optimal windows of critical factors, such as genotypes of plants, conditions of the plants from which explants are prepared, tissue culture methods and culture media, pre-treatments of explants, strains of A. tumefaciens, inducers of virulence genes, transformation vectors, selection marker genes and selective agents, kept technical hurdles high. Eventually it was demonstrated that rice and maize could be transformed by co-cultivating cells of callus cultures or immature embryos, which are actively dividing or about to divide, with A. tumefaciens. Subsequently, these initial difficulties were resolved one by one by many research groups, and the major cereals are now transformed quite efficiently. As many as 15 independent transgenic events may be regenerated from a single piece of immature embryo of rice. Maize transformation protocols are well established, and almost all transgenic events deregulated for commercialization after 2003 were generated by Agrobacterium-mediated transformation. Wheat, barley, and sorghum are also among those plants that can be efficiently transformed by A. tumefaciens.

Progress of cereal transformation technology mediated by Agrobacterium tumefaciens

PubMed Central

Hiei, Yukoh; Ishida, Yuji; Komari, Toshihiko

2014-01-01

Monocotyledonous plants were believed to be not transformable by the soil bacterium Agrobacterium tumefaciens until two decades ago, although convenient protocols for infection of leaf disks and subsequent regeneration of transgenic plants had been well established in a number of dicotyledonous species by then. This belief was reinforced by the fact that monocotyledons are mostly outside the host range of crown gall disease caused by the bacterium and by the failures in trials in monocotyledons to mimic the transformation protocols for dicotyledons. However, a key reason for the failure could have been the lack of active cell divisions at the wound sites in monocotyledons. The complexity and narrow optimal windows of critical factors, such as genotypes of plants, conditions of the plants from which explants are prepared, tissue culture methods and culture media, pre-treatments of explants, strains of A. tumefaciens, inducers of virulence genes, transformation vectors, selection marker genes and selective agents, kept technical hurdles high. Eventually it was demonstrated that rice and maize could be transformed by co-cultivating cells of callus cultures or immature embryos, which are actively dividing or about to divide, with A. tumefaciens. Subsequently, these initial difficulties were resolved one by one by many research groups, and the major cereals are now transformed quite efficiently. As many as 15 independent transgenic events may be regenerated from a single piece of immature embryo of rice. Maize transformation protocols are well established, and almost all transgenic events deregulated for commercialization after 2003 were generated by Agrobacterium-mediated transformation. Wheat, barley, and sorghum are also among those plants that can be efficiently transformed by A. tumefaciens. PMID:25426132

Benzyl Alcohol-Mediated Versatile Method to Fabricate Nonstoichiometric Metal Oxide Nanostructures.

PubMed

Qamar, Mohammad; Adam, Alaaldin; Azad, Abdul-Majeed; Kim, Yong-Wah

2017-11-22

Nanostructured metal oxides with cationic or anionic deficiency find applications in a wide range of technological areas including the energy sector and environment. However, a facile route to prepare such materials in bulk with acceptable reproducibility is still lacking; many synthesis techniques are still only bench-top and cannot be easily scaled-up. Here, we report that the benzyl alcohol (BA)-mediated method is capable of producing a host of nanostructured metal oxides (MO x , where M = Ti, Zn, Ce, Sn, In, Ga, or Fe) with inherent nonstoichiometry. It employs multifunctional BA as a solvent, a reducing agent, and a structure-directing agent. Depending on the oxidation states of metal, elemental or nonstoichiometric oxide forms are obtained. Augmented photoelectrochemical oxidation of water under visible light by some of these nonstoichiometric oxides highlights the versatility of the BA-mediated synthesis protocol.

Highly-efficient liposome-mediated transformation system for the basidiomycetous fungus Flammulina velutipes.

PubMed

Shi, Liang; Chen, Dongdong; Xu, Chao; Ren, Ang; Yu, Hanshou; Zhao, Mingwen

2017-07-11

Flammulina velutipes is a well-known edible mushroom cultivated all over the world. However, because of the low transformation frequency, the expensive instruments required, and the complicated, time-consuming procedures necessary, there is insufficient genetic research on F. velutipes. In this study, we report a liposome-mediated transformation (LMT) system for the genetic transformation of F. velutipes. Using the LMT system, we obtained 82 ± 4 stable F. velutipes transformants per 10 5 protoplasts, which is a clear increase in transformation frequency compared to the other methods used. We were able to detect the expression of an EGFP reporter gene in the F. velutipes transformants using fluorescence imaging assays. Furthermore, we used this method to transfer the laccase gene into F. velutipes and found that the transcriptional level and enzymatic activity increased in these transformants. Mitotic stability analysis showed that all of the selected transformants remained mitotically stable, even after five successive rounds of sub-culturing. These results demonstrate a new transgenic approach that will facilitate F. velutipes research.

Expression of Foreign Genes Demonstrates the Effectiveness of Pollen-Mediated Transformation in Zea mays.

PubMed

Yang, Liyan; Cui, Guimei; Wang, Yixue; Hao, Yaoshan; Du, Jianzhong; Zhang, Hongmei; Wang, Changbiao; Zhang, Huanhuan; Wu, Shu-Biao; Sun, Yi

2017-01-01

Plant genetic transformation has arguably been the core of plant improvement in recent decades. Efforts have been made to develop in planta transformation systems due to the limitations present in the tissue-culture-based methods. Herein, we report an improved in planta transformation system, and provide the evidence of reporter gene expression in pollen tube, embryos and stable transgenicity of the plants following pollen-mediated plant transformation with optimized sonication treatment of pollen. The results showed that the aeration at 4°C treatment of pollen grains in sucrose prior to sonication significantly improved the pollen viability leading to improved kernel set and transformation efficiency. Scanning electron microscopy observation revealed that the removal of operculum covering pollen pore by ultrasonication might be one of the reasons for the pollen grains to become competent for transformation. Evidences have shown that the eGfp gene was expressed in the pollen tube and embryos, and the Cry1Ac gene was detected in the subsequent T 1 and T 2 progenies, suggesting the successful transfer of the foreign genes to the recipient plants. The Southern blot analysis of Cry1Ac gene in T 2 progenies and PCR-identified Apr gene segregation in T 2 seedlings confirmed the stable inheritance of the transgene. The outcome illustrated that the pollen-mediated genetic transformation system can be widely applied in the plant improvement programs with apparent advantages over tissue-culture-based transformation methods.

Optimized conditions for biolistic-mediated transformation of Lilium longilforum 'Nellie White'

USDA-ARS?s Scientific Manuscript database

A variety of tissues were used for biolistic-mediated transformation of Lilum longiflorum 'Nellie White'. Transgenic plants were not recovered from five-month-old, non-embryogenic callus or suspension cells that had been bombarded with pDM327 that contains the bar-uidA fusion gene under control the ...

An approach to crystallizing proteins by metal-mediated synthetic symmetrization

PubMed Central

Laganowsky, Arthur; Zhao, Minglei; Soriaga, Angela B; Sawaya, Michael R; Cascio, Duilio; Yeates, Todd O

2011-01-01

Combining the concepts of synthetic symmetrization with the approach of engineering metal-binding sites, we have developed a new crystallization methodology termed metal-mediated synthetic symmetrization. In this method, pairs of histidine or cysteine mutations are introduced on the surface of target proteins, generating crystal lattice contacts or oligomeric assemblies upon coordination with metal. Metal-mediated synthetic symmetrization greatly expands the packing and oligomeric assembly possibilities of target proteins, thereby increasing the chances of growing diffraction-quality crystals. To demonstrate this method, we designed various T4 lysozyme (T4L) and maltose-binding protein (MBP) mutants and cocrystallized them with one of three metal ions: copper (Cu2+), nickel (Ni2+), or zinc (Zn2+). The approach resulted in 16 new crystal structures—eight for T4L and eight for MBP—displaying a variety of oligomeric assemblies and packing modes, representing in total 13 new and distinct crystal forms for these proteins. We discuss the potential utility of the method for crystallizing target proteins of unknown structure by engineering in pairs of histidine or cysteine residues. As an alternate strategy, we propose that the varied crystallization-prone forms of T4L or MBP engineered in this work could be used as crystallization chaperones, by fusing them genetically to target proteins of interest. PMID:21898649

Metal complex-based electron-transfer mediators in dye-sensitized solar cells

DOEpatents

Elliott, C. Michael; Sapp, Shawn A.; Bignozzi, Carlo Alberto; Contado, Cristiano; Caramori, Stefano

2006-03-28

This present invention provides a metal-ligand complex and methods for using and preparing the same. In particular, the metal-ligand complex of the present invention is of the formula: L.sub.a-M-X.sub.b where L, M, X, a, and b are those define herein. The metal-ligand complexes of the present invention are useful in a variety of applications including as electron-transfer mediators in dye-sensitized solar cells and related photoelectrochromic devices.

Engineered metal based nanomaterials in aqueous environments: Interactions, transformations and implications

NASA Astrophysics Data System (ADS)

Mudunkotuwa, Imali Ama

Nanoscience and nanotechnology offer potential routes towards addressing critical issues such as clean and sustainable energy, environmental protection and human health. Specifically, metal and metal oxide nanomaterials are found in a wide range of applications and therefore hold a greater potential of possible release into the environment or for the human to be exposed. Understanding the aqueous phase behavior of metal and metal oxide nanomaterials is a key factor in the safe design of these materials because their interactions with living systems are always mediated through the aqueous phase. Broadly the transformations in the aqueous phase can be classified as dissolution, aggregation and adsorption which are dependent and linked processes to one another. The complexity of these processes at the liquid-solid interface has therefore been one of the grand challenges that has persisted since the beginning of nanotechnology. Although classical models provide guidance for understanding dissolution and aggregation of nanoparticles in water, there are many uncertainties associated with the recent findings. This is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles. Therefore currently the environmental health and safety studies related to nanomaterials are more focused on understanding the surface chemistry that governs the overall processes in the liquid-solid interfacial region at the molecular level. The metal based nanomaterials focused on in this dissertation include TiO2, ZnO, Cu and CuO. These are among the most heavily used in a number of applications ranging from uses in the construction industry to cosmetic formulation. Therefore they are produced in large scale and have been detected in the environment. There is debate within the scientific community related to their safety as a result of the lack of understanding on the surface interactions that arise from the detailed nature of the surfaces

Contamination of the transformer oil of power transformers and shunting reactors by metal-containing colloidal particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

L'vov, S. Yu.; Komarov, V. B.; Bondareva, V. N.

The results of a measurement of the contamination of the oil in 66 transformers by metal-containing colloidal particles, formed as a result of the interaction of the oil with the structural materials (the copper of the windings, the iron of the tank and core etc.), and also the results of measurements of the optical turbidity of the oil in 136 transformers when they were examined at the Power Engineering Research and Development Center Company are presented. Methods of determining the concentration of copper and iron in transformer oil are considered. The limiting values of the optical turbidity factors, the coppermore » and iron content are determined. These can serve as a basis for taking decisions on whether to replace the silica gel of the filters for continuously purifying the oil of power transformers and the shunting reactors in addition to the standardized oil contamination factors, namely, the dielectric loss tangent and the acidity number of the oil.« less

Factors influencing Agrobacterium-mediated embryogenic callus transformation of Valencia sweet orange (Citrus sinensis) containing the pTA29-barnase gene.

PubMed

Li, D D; Shi, W; Deng, X X

2003-12-01

Valencia sweet orange (Citrus sinensis (L.) Osbeck) calluses were used as explants to develop a new transformation system for citrus mediated by Agrobacterium tumefaciens. Factors affecting Agrobacterium-mediated transformation efficiency included mode of pre-cultivation, temperature of cocultivation and presence of acetosyringone (AS). The highest transformation efficiency was obtained with a 4-day pre-cultivation period in liquid medium. Transformation efficiency was higher when cocultivation was performed for 3 days at 19 degrees C than at 23 or 28 degrees C. Almost no resistant callus was obtained if the cocultivation medium lacked AS. The transformation procedure yielded transgenic Valencia plants containing the pTA29-barnase gene, as verified by PCR amplification and confirmed by Southern blotting. Because male sterility is a common factor leading to seedlessness in citrus cultivars with parthenocarpic characteristics, production of seedless citrus genotypes by Agrobacterium-mediated genetic transformation is a promising alternative to conventional breeding methods.

Agrobacterium tumefaciens-mediated transformation of the entomopathogenic fungus Nomuraea rileyi.

PubMed

Shao, Changwen; Yin, Youping; Qi, Zhaoran; Li, Ren; Song, Zhangyong; Li, Yan; Wang, Zhongkang

2015-10-01

An Agrobacterium-mediated genetic transformation system for the entomopathogenic fungus Nomuraea rileyi was established. Three binary T-DNA vectors, pPZP-Hph, pPZP-Hph-RNAi and pPZP-Hph-DsRed2, were constructed. The trpc promoter from Aspergillus nidulans was used as the cis-regulatory element to drive the expression of hygromycin phosphotransferase (hph) gene and DsRed2, which conferred the hygromycin B (Hyg B) resistance and red fluorescence visualization, respectively. The blastospores and conidia were used as the recipients. The blastospores' transformation efficiency reached ∼20-40 transformants per 10(6) blastospores, whereas the conidia were not transformed. Based on an analysis of five generations of subcultures, PCR and Southern blotting assays, the Ptrpc-hph cassette had integrated into the genomes of all transformants, which contained single copy of the hph gene and showed mitotic stability. Abundant altered morphologic phenotypes in colonies, blastospores and hyphae formations were observed in the arbitrary insertional mutants of N. rileyi, which made it possible to study the relationships between the functions and the interrupted genes over the whole genome. The transformation protocol will promote the functional characterization of genes, and the construction of genetically engineered strains of this important entomopathogenic fungus, and potentially of other similar fungal pathogens. Copyright © 2015 Elsevier Inc. All rights reserved.

Heavy metals resistant plasmid-mediated utilization of solar by Pseudomonas aeruginosa AA301.

PubMed

Abo-Amer, Aly E; Mohamed, Rehab M

2006-01-01

Solar-degrading bacteria, Pseudomonas aeruginosa strains, were isolated from Egyptian soil by Mineral Salt Medium (MSM) supplemented with Solar (motor fuel) from different oil-contaminated sites in Sohag province. The strain AA301 of Pseudomonas aeruginosa showed appreciable growth in MSM medium containing high concentrations of Solar ranging from 0.5 to 3% (v/v), with optimum concentration at 1.5%. Solar was used as a sole carbon source and a source of energy by the bacterium. The ability to degrade Solar was found to be associated with a single 60-kb plasmid designated pSOL15. The plasmid-cured variant, which was obtained by culturing in LB broth with kanamycin, lost the plasmid indicative the ability to degrade Solar must depend on this plasmid. The wild type isolate, Pseudomonas aeruginosa AA301 and transformant strain, have maximum growth (OD600 = approximately 2) on Solar, however the plasmid-cured variant did not have any significant growth on Solar. Moreover, resistance to a wide range of heavy metals such as Mn2+, Hg2+, Mg2+, Cd2+, Zn2+, and Ni2+ was also 60-kb plasmid-mediated. Therefore, the strain AA301 could be good candidate for remediation of some heavy metals and oil hydrocarbons in heavily polluted sites.

Agrobacterium-mediated transformation of the haploid liverwort Marchantia polymorpha L., an emerging model for plant biology.

PubMed

Ishizaki, Kimitsune; Chiyoda, Shota; Yamato, Katsuyuki T; Kohchi, Takayuki

2008-07-01

Agrobacterium-mediated transformation has not been practical in pteridophytes, bryophytes and algae to date, although it is commonly used in model plants including Arabidopsis and rice. Here we present a rapid Agrobacterium-mediated transformation system for the haploid liverwort Marchantia polymorpha L. using immature thalli developed from spores. Hundreds of hygromycin-resistant plants per sporangium were obtained by co-cultivation of immature thalli with Agrobacterium carrying the binary vector that contains a reporter, the beta-glucuronidase (GUS) gene with an intron, and a selection marker, the hygromycin phosphotransferase (hpt) gene. In this system, individual gemmae, which arise asexually from single initial cells, were analyzed as isogenic transformants. GUS activity staining showed that all hygromycin-resistant plants examined expressed the GUS transgene in planta. DNA analyses verified random integration of 1-5 copies of the intact T-DNA between the right and the left borders into the M. polymorpha genome. The efficient and rapid Agrobacterium-mediated transformation of M. polymorpha should provide molecular techniques to facilitate comparative genomics, taking advantage of this unique model plant that retains many features of the common ancestor of land plants.

Metal chaperones prevent zinc-mediated cognitive decline.

PubMed

Adlard, Paul A; Parncutt, Jacqui; Lal, Varsha; James, Simon; Hare, Dominic; Doble, Philip; Finkelstein, David I; Bush, Ashley I

2015-09-01

Zinc transporter-3 (ZnT3) protein is responsible for loading zinc into presynaptic vesicles and consequently controls the availability of zinc at the glutamatergic synapse. ZnT3 has been shown to decline with age and in Alzheimer's disease (AD) and is crucially involved in learning and memory. In this study, we utilised whole animal behavioural analyses in the ZnT3 KO mouse line, together with electrophysiological analysis of long-term potentiation in brain slices from ZnT3 KO mice, to show that metal chaperones (clioquinol, 30 mg/kg/day for 6weeks) can prevent the age-dependent cognitive phenotype that characterises these animals. This likely occurs as a result of a homeostatic restoration of synaptic protein expression, as clioquinol significantly restored levels of various pre- and postsynaptic proteins that are critical for normal cognition, including PSD-95; AMPAR and NMDAR2b. We hypothesised that this clioquinol-mediated restoration of synaptic health resulted from a selective increase in synaptic zinc content within the hippocampus. While we demonstrated a small regional increase in hippocampal zinc content using synchrotron x-ray fluorescence microscopy, further sub-region analyses are required to determine whether this effect is seen in other regions of the hippocampal formation that are more closely linked to the synaptic plasticity effects observed in this study. These data support our recent report on the use of a different metal chaperone (PBT2) to prevent normal age-related cognitive decline and demonstrate that metal chaperones are efficacious in preventing the zinc-mediated cognitive decline that characterises ageing and disease. Copyright © 2014 Elsevier Inc. All rights reserved.

Metal-mediated DNA base pairing: alternatives to hydrogen-bonded Watson-Crick base pairs.

PubMed

Takezawa, Yusuke; Shionoya, Mitsuhiko

2012-12-18

With its capacity to store and transfer the genetic information within a sequence of monomers, DNA forms its central role in chemical evolution through replication and amplification. This elegant behavior is largely based on highly specific molecular recognition between nucleobases through the specific hydrogen bonds in the Watson-Crick base pairing system. While the native base pairs have been amazingly sophisticated through the long history of evolution, synthetic chemists have devoted considerable efforts to create alternative base pairing systems in recent decades. Most of these new systems were designed based on the shape complementarity of the pairs or the rearrangement of hydrogen-bonding patterns. We wondered whether metal coordination could serve as an alternative driving force for DNA base pairing and why hydrogen bonding was selected on Earth in the course of molecular evolution. Therefore, we envisioned an alternative design strategy: we replaced hydrogen bonding with another important scheme in biological systems, metal-coordination bonding. In this Account, we provide an overview of the chemistry of metal-mediated base pairing including basic concepts, molecular design, characteristic structures and properties, and possible applications of DNA-based molecular systems. We describe several examples of artificial metal-mediated base pairs, such as Cu(2+)-mediated hydroxypyridone base pair, H-Cu(2+)-H (where H denotes a hydroxypyridone-bearing nucleoside), developed by us and other researchers. To design the metallo-base pairs we carefully chose appropriate combinations of ligand-bearing nucleosides and metal ions. As expected from their stronger bonding through metal coordination, DNA duplexes possessing metallo-base pairs exhibited higher thermal stability than natural hydrogen-bonded DNAs. Furthermore, we could also use metal-mediated base pairs to construct or induce other high-order structures. These features could lead to metal-responsive functional

Establishment of an efficient genetic transformation method in Dunaliella tertiolecta mediated by Agrobacterium tumefaciens.

PubMed

Norzagaray-Valenzuela, Claudia D; Germán-Báez, Lourdes J; Valdez-Flores, Marco A; Hernández-Verdugo, Sergio; Shelton, Luke M; Valdez-Ortiz, Angel

2018-05-16

Microalgae are photosynthetic microorganisms widely used for the production of highly valued compounds, and recently they have been shown to be promising as a system for the heterologous expression of proteins. Several transformation methods have been successfully developed, from which the Agrobacterium tumefaciens-mediated method remains the most promising. However, microalgae transformation efficiency by A. tumefaciens is shown to vary depending on several transformation conditions. The present study aimed to establish an efficient genetic transformation system in the green microalgae Dunaliella tertiolecta using the A. tumefaciens method. The parameters assessed were the infection medium, the concentration of the A. tumefaciens and co-culture time. As a preliminary screening, the expression of the gusA gene and the viability of transformed cells were evaluated and used to calculate a novel parameter called Transformation Efficiency Index (TEI). The statistical analysis of TEI values showed five treatments with the highest gusA gene expression. To ensure stable transformation, transformed colonies were cultured on selective medium using hygromycin B and the DNA of resistant colonies were extracted after five subcultures and molecularly analyzed by PCR. Results revealed that treatments which use solid infection medium, A. tumefaciens OD 600  = 0.5 and co-culture times of 72 h exhibited the highest percentage of stable gusA expression. Overall, this study established an efficient, optimized A. tumefaciens-mediated genetic transformation of D. tertiolecta, which represents a relatively easy procedure with no expensive equipment required. This simple and efficient protocol opens the possibility for further genetic manipulation of this commercially-important microalgae for biotechnological applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Critical indices for reversible gamma-alpha phase transformation in metallic cerium

NASA Astrophysics Data System (ADS)

Soldatova, E. D.; Tkachenko, T. B.

1980-08-01

Critical indices for cerium have been determined within the framework of the pseudobinary solution theory along the phase equilibrium curve, the critical isotherm, and the critical isobar. The results obtained verify the validity of relationships proposed by Rushbrook (1963), Griffiths (1965), and Coopersmith (1968). It is concluded that reversible gamma-alpha transformation in metallic cerium is a critical-type transformation, and cerium has a critical point on the phase diagram similar to the critical point of the liquid-vapor system.

Agrobacterium-mediated transformation of two Serbian potato cultivars (Solanum tuberosum L. cv. Dragacevka and cv. Jelica)

USDA-ARS?s Scientific Manuscript database

An efficient protocol for Agrobacterium-mediated transformation of Serbian potato cultivars Dragacevka and Jelica, enabling the introduction of oryzacystatin genes OCI and OCII, was established. Starting with leaf explants a two-stage transformation protocol combining procedures of Webb and Wenzler...

A comparison of Agrobacterium-mediated transformation and protoplast-mediated transformation with CRISPR-Cas9 and bipartite gene targeting substrates, as effective gene targeting tools for Aspergillus carbonarius.

PubMed

Weyda, István; Yang, Lei; Vang, Jesper; Ahring, Birgitte K; Lübeck, Mette; Lübeck, Peter S

2017-04-01

In recent years, versatile genetic tools have been developed and applied to a number of filamentous fungi of industrial importance. However, the existing techniques have limitations when it comes to achieve the desired genetic modifications, especially for efficient gene targeting. In this study, we used Aspergillus carbonarius as a host strain due to its potential as a cell factory, and compared three gene targeting techniques by disrupting the ayg1 gene involved in the biosynthesis of conidial pigment in A. carbonarius. The absence of the ayg1 gene leads to phenotypic change in conidia color, which facilitated the analysis on the gene targeting frequency. The examined transformation techniques included Agrobacterium-mediated transformation (AMT) and protoplast-mediated transformation (PMT). Furthermore, the PMT for the disruption of the ayg1 gene was carried out with bipartite gene targeting fragments and the recently adapted CRISPR-Cas9 system. All three techniques were successful in generating Δayg1 mutants, but showed different efficiencies. The most efficient method for gene targeting was AMT, but further it was shown to be dependent on the choice of Agrobacterium strain. However, there are different advantages and disadvantages of all three gene targeting methods which are discussed, in order to facilitate future approaches for fungal strain improvements. Copyright © 2017 Elsevier B.V. All rights reserved.

High-efficiency Agrobacterium-mediated transformation of Norway spruce (Picea abies) and loblolly pine (Pinus taeda)

NASA Technical Reports Server (NTRS)

Wenck, A. R.; Quinn, M.; Whetten, R. W.; Pullman, G.; Sederoff, R.; Brown, C. S. (Principal Investigator)

1999-01-01

Agrobacterium-mediated gene transfer is the method of choice for many plant biotechnology laboratories; however, large-scale use of this organism in conifer transformation has been limited by difficult propagation of explant material, selection efficiencies and low transformation frequency. We have analyzed co-cultivation conditions and different disarmed strains of Agrobacterium to improve transformation. Additional copies of virulence genes were added to three common disarmed strains. These extra virulence genes included either a constitutively active virG or extra copies of virG and virB, both from pTiBo542. In experiments with Norway spruce, we increased transformation efficiencies 1000-fold from initial experiments where little or no transient expression was detected. Over 100 transformed lines expressing the marker gene beta-glucuronidase (GUS) were generated from rapidly dividing embryogenic suspension-cultured cells co-cultivated with Agrobacterium. GUS activity was used to monitor transient expression and to further test lines selected on kanamycin-containing medium. In loblolly pine, transient expression increased 10-fold utilizing modified Agrobacterium strains. Agrobacterium-mediated gene transfer is a useful technique for large-scale generation of transgenic Norway spruce and may prove useful for other conifer species.

A rapid, highly efficient and economical method of Agrobacterium-mediated in planta transient transformation in living onion epidermis.

PubMed

Xu, Kedong; Huang, Xiaohui; Wu, Manman; Wang, Yan; Chang, Yunxia; Liu, Kun; Zhang, Ju; Zhang, Yi; Zhang, Fuli; Yi, Liming; Li, Tingting; Wang, Ruiyue; Tan, Guangxuan; Li, Chengwei

2014-01-01

Transient transformation is simpler, more efficient and economical in analyzing protein subcellular localization than stable transformation. Fluorescent fusion proteins were often used in transient transformation to follow the in vivo behavior of proteins. Onion epidermis, which has large, living and transparent cells in a monolayer, is suitable to visualize fluorescent fusion proteins. The often used transient transformation methods included particle bombardment, protoplast transfection and Agrobacterium-mediated transformation. Particle bombardment in onion epidermis was successfully established, however, it was expensive, biolistic equipment dependent and with low transformation efficiency. We developed a highly efficient in planta transient transformation method in onion epidermis by using a special agroinfiltration method, which could be fulfilled within 5 days from the pretreatment of onion bulb to the best time-point for analyzing gene expression. The transformation conditions were optimized to achieve 43.87% transformation efficiency in living onion epidermis. The developed method has advantages in cost, time-consuming, equipment dependency and transformation efficiency in contrast with those methods of particle bombardment in onion epidermal cells, protoplast transfection and Agrobacterium-mediated transient transformation in leaf epidermal cells of other plants. It will facilitate the analysis of protein subcellular localization on a large scale.

A Rapid, Highly Efficient and Economical Method of Agrobacterium-Mediated In planta Transient Transformation in Living Onion Epidermis

PubMed Central

Xu, Kedong; Huang, Xiaohui; Wu, Manman; Wang, Yan; Chang, Yunxia; Liu, Kun; Zhang, Ju; Zhang, Yi; Zhang, Fuli; Yi, Liming; Li, Tingting; Wang, Ruiyue; Tan, Guangxuan; Li, Chengwei

2014-01-01

Transient transformation is simpler, more efficient and economical in analyzing protein subcellular localization than stable transformation. Fluorescent fusion proteins were often used in transient transformation to follow the in vivo behavior of proteins. Onion epidermis, which has large, living and transparent cells in a monolayer, is suitable to visualize fluorescent fusion proteins. The often used transient transformation methods included particle bombardment, protoplast transfection and Agrobacterium-mediated transformation. Particle bombardment in onion epidermis was successfully established, however, it was expensive, biolistic equipment dependent and with low transformation efficiency. We developed a highly efficient in planta transient transformation method in onion epidermis by using a special agroinfiltration method, which could be fulfilled within 5 days from the pretreatment of onion bulb to the best time-point for analyzing gene expression. The transformation conditions were optimized to achieve 43.87% transformation efficiency in living onion epidermis. The developed method has advantages in cost, time-consuming, equipment dependency and transformation efficiency in contrast with those methods of particle bombardment in onion epidermal cells, protoplast transfection and Agrobacterium-mediated transient transformation in leaf epidermal cells of other plants. It will facilitate the analysis of protein subcellular localization on a large scale. PMID:24416168

The migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge.

PubMed

Huang, Hua-Jun; Yuan, Xing-Zhong

2016-01-01

Various hydrothermal treatment methods, including hydrothermal carbonization, liquefaction and sub/super-critical water gasification, have been applied to the disposal of sewage sludge for producing bio-materials or bio-fuels. It has become a research hotspot whether the heavy metals contained in sewage sludge can be well treated/stabilized after the hydrothermal treatments. This review firstly summarized the methods of assessing heavy metals' contamination level/risk and then discussed the migration and transformation behaviors of heavy metals from the following aspects: the effect of reaction temperature, the effect of additives (catalysts and other biomass), the effect of the type of solvent and the effect of reaction time. This review can provide an important reference for the further study of the migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Efficient PEG/CaCl₂-Mediated Transformation Approach for the Medicinal Fungus Wolfiporia cocos.

PubMed

Sun, Qiao; Wei, Wei; Zhao, Juan; Song, Jia; Peng, Fang; Zhang, Shaopeng; Zheng, Yonglian; Chen, Ping; Zhu, Wenjun

2015-09-01

Sclerotia of Wolfiporia cocos are of medicinal and culinary value. The genes and molecular mechanisms involved in W. cocos sclerotial formation are poorly investigated because of the lack of a suitable and reproducible transformation system for W. cocos. In this study, a PEG/ CaCl₂-mediated genetic transformation system for W. cocos was developed. The promoter Pgpd from Ganoderma lucidum effectively drove expression of the hygromycin B phosphotransferase gene in W. cocos, and approximately 30 transformants were obtained per 10 μg DNA when the protoplast suspension density was 10(6) protoplasts/ml. However, no transformants were obtained under the regulation of the PtrpC promoter from Aspergillus nidulans.

Differential roles of glucosinolates and camalexin at different stages of Agrobacterium-mediated transformation.

PubMed

Shih, Po-Yuan; Chou, Shu-Jen; Müller, Caroline; Halkier, Barbara Ann; Deeken, Rosalia; Lai, Erh-Min

2018-03-02

Agrobacterium tumefaciens is the causal agent of crown gall disease in a wide range of plants via a unique interkingdom DNA transfer from bacterial cells into the plant genome. Agrobacterium tumefaciens is capable of transferring its T-DNA into different plant parts at different developmental stages for transient and stable transformation. However, the plant genes and mechanisms involved in these transformation processes are not well understood. We used Arabidopsis thaliana Col-0 seedlings to reveal the gene expression profiles at early time points during Agrobacterium infection. Common and differentially expressed genes were found in shoots and roots. A gene ontology analysis showed that the glucosinolate (GS) biosynthesis pathway was an enriched common response. Strikingly, several genes involved in indole glucosinolate (iGS) modification and the camalexin biosynthesis pathway were up-regulated, whereas genes in aliphatic glucosinolate (aGS) biosynthesis were generally down-regulated, on Agrobacterium infection. Thus, we evaluated the impacts of GSs and camalexin during different stages of Agrobacterium-mediated transformation combining Arabidopsis mutant studies, metabolite profiling and exogenous applications of various GS hydrolysis products or camalexin. The results suggest that the iGS hydrolysis pathway plays an inhibitory role on transformation efficiency in Arabidopsis seedlings at the early infection stage. Later in the Agrobacterium infection process, the accumulation of camalexin is a key factor inhibiting tumour development on Arabidopsis inflorescence stalks. In conclusion, this study reveals the differential roles of GSs and camalexin at different stages of Agrobacterium-mediated transformation and provides new insights into crown gall disease control and improvement of plant transformation. © 2018 THE AUTHORS. MOLECULAR PLANT PATHOLOGY PUBLISHED BY BRITISH SOCIETY FOR PLANT PATHOLOGY AND JOHN WILEY & SONS LTD.

Phytoremediation using microbially mediated metal accumulation in Sorghum bicolor.

PubMed

Phieler, René; Merten, Dirk; Roth, Martin; Büchel, Georg; Kothe, Erika

2015-12-01

Reclaiming land that has been anthropogenically contaminated with multiple heavy metal elements, e.g., during mining operations, is a growing challenge worldwide. The use of phytoremediation has been discussed with varying success. Here, we show that a careful examination of options of microbial determination of plant performance is a key element in providing a multielement remediation option for such landscapes. We used both (a) mycorrhiza with Rhizophagus irregularis and (b) bacterial amendments with Streptomyces acidiscabies E13 and Streptomyces tendae F4 to mediate plant-promoting and metal-accumulating properties to Sorghum bicolor. In pot experiments, the effects on plant growth and metal uptake were scored, and in a field trial at a former uranium leaching heap site near Ronneburg, Germany, we could show the efficacy under field conditions. Different metals could be extracted at the same time, with varying microbial inoculation and soil amendment scenarios possible when a certain metal is the focus of interest. Especially, manganese was extracted at very high levels which might be useful even for phytomining approaches.

Mediating the effects of work-life conflict between transformational leadership and health-care workers' job satisfaction and psychological wellbeing.

PubMed

Munir, Fehmidah; Nielsen, Karina; Garde, Anne H; Albertsen, Karen; Carneiro, Isabella G

2012-05-01

To explore the mediating effects of work-life conflict between transformational leadership and job satisfaction and psychological wellbeing. The importance of work-life balance for job satisfaction and wellbeing among health-care employees is well-recognized. Evidence shows that transformational leadership style is linked to psychological wellbeing. It is possible that transformational leadership is also associated with employees' perceptions of work-life conflict, thereby influencing their job satisfaction and wellbeing. A longitudinal design was used where staff working within Danish elderly care completed a questionnaire at baseline and 18-month follow-up (N=188). Regression analyses showed that transformational leadership style was directly associated with perceptions of work-life conflict, job satisfaction and psychological wellbeing. Work-life conflict mediated between transformational leadership and wellbeing, but not job satisfaction. The findings suggest transformational leadership style may improve perceptions of work-life balance and employee wellbeing. Managers should adopt transformational leadership styles to reduce work-life conflict and enhance the wellbeing of their staff. © 2011 Blackwell Publishing Ltd.

Promoting safety voice with safety-specific transformational leadership: the mediating role of two dimensions of trust.

PubMed

Conchie, Stacey M; Taylor, Paul J; Donald, Ian J

2012-01-01

Although safety-specific transformational leadership is known to encourage employee safety voice behaviors, less is known about what makes this style of leadership effective. We tested a model that links safety-specific transformational leadership to safety voice through various dimensions of trust. Data from 150 supervisor-employee dyads from the United Kingdom oil industry supported our predictions that the effects of safety-specific transformational leadership are sequentially mediated by affect-based trust beliefs and disclosure trust intentions. Moreover, we found that reliance trust intentions moderated the effect of disclosure: employees' disclosure intentions mediated the effects of affect-based trust on safety voice behaviors only when employees' intention to rely on their leader was moderate to high. These findings suggest that leaders seeking to encourage safety voice behaviors should go beyond "good reason" arguments and develop affective bonds with their employees.

Controlling the plasmonic surface waves of metallic nanowires by transformation optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yichao; Yuan, Jun; Yin, Ge

2015-07-06

In this letter, we introduce the technique of using transformation optics to manipulate the mode states of surface plasmonic waves of metallic nanowire waveguides. As examples we apply this technique to design two optical components: a three-dimensional (3D) electromagnetic mode rotator and a mode convertor. The rotator can rotate the polarization state of the surface wave around plasmonic nanowires by arbitrarily desired angles, and the convertor can transform the surface wave modes from one to another. Full-wave simulation is performed to verify the design and efficiency of our devices. Their potential application in photonic circuits is envisioned.

Agrobacterium-mediated transformation in Alpinia galanga (Linn.) Willd. for enhanced acetoxychavicol acetate production.

PubMed

Rao, Kiranmayee; Chodisetti, Bhuvaneswari; Mangamoori, Lakshmi Narasu; Giri, Archana

2012-09-01

Agrobacterium-mediated transformations ensure elevated amounts of secondary metabolite accumulation with genetic and biosynthetic stability. In the present study, Alpinia galanga rich in bioactive compounds was genetically transformed using different strains of Agrobacterium rhizogenes viz. LBA 9402, A(4), 532, 2364 and PRTGus. Even though a higher growth rate was obtained with the LBA 9402 strain, maximum acetoxychavicol acetate accumulation (ACA) was seen in the PRTGus transformant. PRTGus root line has shown 10.1 fold higher ACA content in comparison to the control roots. The lowest ACA production was shown by the A(4) transformant (4.9 fold). The quantification of ACA in the transformed roots was carried out by using HPLC, which was found to be in the order of PRTGus > LBA 9402 > 2364 > 532 > A(4). The fast growth rate of hairy roots, genetic stability and their ability to synthesize more than one metabolite offer a promising system for the production of valuable secondary metabolites.

An efficient Agrobacterium-mediated transformation method for the edible mushroom Hypsizygus marmoreus.

PubMed

Zhang, Jin jing; Shi, Liang; Chen, Hui; Sun, Yun qi; Zhao, Ming wen; Ren, Ang; Chen, Ming jie; Wang, Hong; Feng, Zhi yong

2014-01-01

Hypsizygus marmoreus is one of the major edible mushrooms in East Asia. As no efficient transformation method, the molecular and genetics studies were hindered. The glyceraldehyde-3-phosphate dehydrogenase (GPD) gene of H. marmoreus was isolated and its promoter was used to drive the hygromycin B phosphotransferase (HPH) and enhanced green fluorescent protein (EGFP) in H. marmoreus. Agrobacterium tumefaciens-mediated transformation (ATMT) was successfully applied in H. marmoreus. The transformation parameters were optimized, and it was found that co-cultivation of bacteria with protoplast at a ratio of 1000:1 at a temperature of 26 °C in medium containing 0.3 mM acetosyringone resulted in the highest transformation efficiency for Agrobacterium strain. Besides, three plasmids, each carrying a different promoter (from H. marmoreus, Ganoderma lucidum and Lentinula edodes) driving the expression of an antibiotic resistance marker, were also tested. The construct carrying the H. marmoreus gpd promoter produced more transformants than other constructs. Our analysis showed that over 85% of the transformants tested remained mitotically stable even after five successive rounds of subculturing. Putative transformants were analyzed for the presence of hph gene by PCR and Southern blot. Meanwhile, the expression of EGFP in H. marmoreus transformants was detected by fluorescence imaging. This ATMT system increases the transformation efficiency of H. marmoreus and may represent a useful tool for molecular genetic studies in this mushroom species. Copyright © 2014 Elsevier GmbH. All rights reserved.

Biotic and abiotic retention, recycling and remineralization of metals in the ocean

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, Philip W.; Ellwood, Michael J.; Tagliabue, Alessandro

Trace metals shape both the biogeochemical functioning and biological structure of oceanic provinces. Trace metal biogeochemistry has primarily focused on modes of external supply of metals from aeolian, hydrothermal, sedimentary and other sources. However, metals also undergo internal transformations such as abiotic and biotic retention, recycling and remineralization. The role of these internal transformations in metal biogeochemical cycling is now coming into focus. First, the retention of metals by biota in the surface ocean for days, weeks or months depends on taxon-specific metal requirements of phytoplankton, and on their ultimate fate: that is, viral lysis, senescence, grazing and/or export tomore » depth. Rapid recycling of metals in the surface ocean can extend seasonal productivity by maintaining higher levels of metal bioavailability compared to the influence of external metal input alone. As metal-containing organic particles are exported from the surface ocean, different metals exhibit distinct patterns of remineralization with depth. These patterns are mediated by a wide range of physicochemical and microbial processes such as the ability of particles to sorb metals, and are influenced by the mineral and organic characteristics of sinking particles. We conclude that internal metal transformations play an essential role in controlling metal bioavailability, phytoplankton distributions and the subsurface resupply of metals.« less

Agrobacterium-Mediated Transformation of Bread and Durum Wheat Using Freshly Isolated Immature Embryos

NASA Astrophysics Data System (ADS)

Huixia, Wu; Angela, Doherty; Jones, Huw D.

Agrobacterium-mediated transformation of wheat is becoming a viable alternative to the more established biolistic protocols. It offers advantages in terms of simple, low-copy-number integrations and can be applied with similar efficiencies to specific durum wheat and spring and winter bread wheat types varieties.

Adaptive self-assembly and induced-fit transformations of anion-binding metal-organic macrocycles

NASA Astrophysics Data System (ADS)

Zhang, Ting; Zhou, Li-Peng; Guo, Xiao-Qing; Cai, Li-Xuan; Sun, Qing-Fu

2017-06-01

Container-molecules are attractive to chemists due to their unique structural characteristics comparable to enzymes and receptors in nature. We report here a family of artificial self-assembled macrocyclic containers that feature induced-fit transformations in response to different anionic guests. Five metal-organic macrocycles with empirical formula of MnL2n (M=Metal L=Ligand n=3, 4, 5, 6, 7) are selectively obtained starting from one simple benzimidazole-based ligand and square-planar palladium(II) ions, either by direct anion-adaptive self-assembly or induced-fit transformations. Hydrogen-bonding interactions between the inner surface of the macrocycles and the anionic guests dictate the shape and size of the product. A comprehensive induced-fit transformation map across all the MnL2n species is drawn, with a representative reconstitution process from Pd7L14 to Pd3L6 traced in detail, revealing a gradual ring-shrinking mechanism. We envisage that these macrocyclic molecules with adjustable well-defined hydrogen-bonding pockets will find wide applications in molecular sensing or catalysis.

Plant Cell Division Analyzed by Transient Agrobacterium-Mediated Transformation of Tobacco BY-2 Cells.

PubMed

Buschmann, Henrik

2016-01-01

The continuing analysis of plant cell division will require additional protein localization studies. This is greatly aided by GFP-technology, but plant transformation and the maintenance of transgenic lines can present a significant technical bottleneck. In this chapter I describe a method for the Agrobacterium-mediated genetic transformation of tobacco BY-2 cells. The method allows for the microscopic analysis of fluorescence-tagged proteins in dividing cells in within 2 days after starting a coculture. This transient transformation procedure requires only standard laboratory equipment. It is hoped that this rapid method would aid researchers conducting live-cell localization studies in plant mitosis and cytokinesis.

Effects of Grazing on Bacteria-Mediated Corrosion of Metals in Seawater

DTIC Science & Technology

1986-05-01

NUMBEER2. GOVT ACCESSION NO. 3. RECIPIENT’S CATA’.00 NJUMIIER 4. TITLE (mESubtitle) S*TYPE OF REPORT a ’!;.iOO COVERED IL’ Effects of Grazing on... Effects of Grazing on Bacteria-Mediated Corrosion of Metals in Seawater ONR Contract No. : N00014-83-0652 Project Period: August 1983-August, 1985 Principal...the laboratory to address the next two objectives. II. Effect of Protozoa on Total Numbers of Bacteria on Metals This objective included testing a

Characteristics and Kinetic Analysis of AQS Transformation and Microbial Goethite Reduction:Insight into "Redox mediator-Microbe-Iron oxide" Interaction Process.

PubMed

Zhu, Weihuang; Shi, Mengran; Yu, Dan; Liu, Chongxuan; Huang, Tinglin; Wu, Fengchang

2016-03-29

The characteristics and kinetics of redox transformation of a redox mediator, anthraquinone-2-sulfonate (AQS), during microbial goethite reduction by Shewanella decolorationis S12, a dissimilatory iron reduction bacterium (DIRB), were investigated to provide insights into "redox mediator-iron oxide" interaction in the presence of DIRB. Two pre-incubation reaction systems of the "strain S12- goethite" and the "strain S12-AQS" were used to investigate the dynamics of goethite reduction and AQS redox transformation. Results show that the concentrations of goethite and redox mediator, and the inoculation cell density all affect the characteristics of microbial goethite reduction, kinetic transformation between oxidized and reduced species of the redox mediator. Both abiotic and biotic reactions and their coupling regulate the kinetic process for "Quinone-Iron" interaction in the presence of DIRB. Our results provide some new insights into the characteristics and mechanisms of interaction among "quinone-DIRB- goethite" under biotic/abiotic driven.

An efficient Agrobacterium-mediated transformation method for aflatoxin generation fungus Aspergillus flavus.

PubMed

Han, Guomin; Shao, Qian; Li, Cuiping; Zhao, Kai; Jiang, Li; Fan, Jun; Jiang, Haiyang; Tao, Fang

2018-05-01

Aspergillus flavus often invade many important corps and produce harmful aflatoxins both in preharvest and during storage stages. The regulation mechanism of aflatoxin biosynthesis in this fungus has not been well explored mainly due to the lack of an efficient transformation method for constructing a genome-wide gene mutant library. This challenge was resolved in this study, where a reliable and efficient Agrobacterium tumefaciens-mediated transformation (ATMT) protocol for A. flavus NRRL 3357 was established. The results showed that removal of multinucleate conidia, to collect a homogenous sample of uninucleate conidia for use as the transformation material, is the key step in this procedure. A. tumefaciens strain AGL-1 harboring the ble gene for zeocin resistance under the control of the gpdA promoter from A. nidulans is suitable for genetic transformation of this fungus. We successfully generated A. flavus transformants with an efficiency of ∼ 60 positive transformants per 10 6 conidia using our protocol. A small-scale insertional mutant library (∼ 1,000 mutants) was constructed using this method and the resulting several mutants lacked both production of conidia and aflatoxin biosynthesis capacity. Southern blotting analysis demonstrated that the majority of the transformants contained a single T-DNA insert on the genome. To the best of our knowledge, this is the first report of genetic transformation of A. flavus via ATMT and our protocol provides an effective tool for construction of genome-wide gene mutant libraries for functional analysis of important genes in A. flavus.

Strain-dependent activation energy of shear transformation in metallic glasses

NASA Astrophysics Data System (ADS)

Xu, Bin; Falk, Michael; Li, Jinfu; Kong, Lingti

2017-04-01

Shear transformation (ST) plays a decisive role in determining the mechanical behavior of metallic glasses, which is believed to be a stress-assisted thermally activated process. Understanding the dependence in its activation energy on the stress imposed on the material is of central importance to model the deformation process of metallic glasses and other amorphous solids. Here a theoretical model is proposed to predict the variation of the minimum energy path (MEP) associated with a particular ST event upon further deformation. Verification based on atomistic simulations and calculations are also conducted. The proposed model reproduces the MEP and activation energy of an ST event under different imposed macroscopic strains based on a known MEP at a reference strain. Moreover, an analytical approach is proposed based on the atomistic calculations, which works well when the stress varies linearity along the MEP. These findings provide necessary background for understanding the activation processes and, in turn, the mechanical behavior of metallic glasses.

Nano-MnO2-mediated transformation of triclosan with humic molecules present: kinetics, products, and pathways.

PubMed

Sun, Kai; Li, Shunyao; Waigi, Michael Gatheru; Huang, Qingguo

2018-05-01

It has been shown that manganese dioxide (MnO 2 ) can mediate transformation of phenolic contaminants to form phenoxyl radical intermediates, and subsequently, these intermediates intercouple to form oligomers via covalent binding. However, the reaction kinetics and transformation mechanisms of phenolic contaminants with humic molecules present in nano-MnO 2 -mediated systems were still unclear. In this study, it was proven that nano-MnO 2 were effective in transforming triclosan under acidic conditions (pH 3.5-5.0) during manganese reduction, and the apparent pseudo first-order kinetics rate constants (k = 0.0599-1.5314 h -1 ) increased as the pH decreased. In particular, the transformation of triclosan by nano-MnO 2 was enhanced in the presence of low-concentration humic acid (1-10 mg L -1 ). The variation in the absorption of humic molecules at 275 nm supported possible covalent binding between humic molecules and triclosan in the nano-MnO 2 -mediated systems. A total of four main intermediate products were identified by high-resolution mass spectrometry (HRMS), regardless of humic molecules present in the systems or not. These products correspond to a suite of radical intercoupling reactions (dimers and trimers), ether cleavage (2,4-dichlorophenol), and oxidation to quinone-like products, triggered by electron transfer from triclosan molecules to nano-MnO 2 . A possible reaction pathway in humic acid solutions, including homo-coupling, decomposition, oxidation, and cross-coupling, was proposed. Our findings provide valuable information regarding the environmental fate and transformation mechanism of triclosan by nano-MnO 2 in complex water matrices.

Stable ABTS Immobilized in the MIL-100(Fe) Metal-Organic Framework as an Efficient Mediator for Laccase-Catalyzed Decolorization.

PubMed

Liu, Youxun; Geng, Yuanyuan; Yan, Mingyang; Huang, Juan

2017-06-02

The successful encapsulation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), a well-known laccase mediator, within a mesoporous metal-organic framework sample (i.e., MIL-100(Fe)) was achieved using a one-pot hydrothermal synthetic method. The as-prepared ABTS@MIL-100(Fe) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nitrogen sorption, and cyclic voltammetry (CV). Our ABTS@MIL-100(Fe)-based electrode exhibited an excellent electrochemical response, indicating that MIL-100(Fe) provides an appropriate microenvironment for the immobilization and electroactivity of ABTS molecules. ABTS@MIL-100(Fe) was then evaluated as an immobilized laccase mediator for dye removal using indigo carmine (IC) as a model dye. Through the application of laccase in combination with a free (ABTS) or immobilized (ABTS@MIL-100(Fe)) mediator, decolorization yields of 95% and 94%, respectively, were obtained for IC after 50 min. In addition, following seven reuse cycles of ABTS@MIL-100(Fe) for dye treatment, a decolorization yield of 74% was obtained. Dye decolorization occurred through the breakdown of the chromophoric group by the Laccase/ABTS@MIL-100(Fe) system, and a catalytic mechanism was proposed. We therefore expect that the stability, reusability, and validity of ABTS@MIL-100(Fe) as a laccase mediator potentially render it a promising tool for dye removal, in addition to reducing the high running costs and potential toxicity associated with synthetic mediators.

Mechanisms of Contact-Mediated Killing of Yeast Cells on Dry Metallic Copper Surfaces▿

PubMed Central

Quaranta, Davide; Krans, Travis; Santo, Christophe Espírito; Elowsky, Christian G.; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

2011-01-01

Surfaces made of copper or its alloys have strong antimicrobial properties against a wide variety of microorganisms. However, the molecular mode of action responsible for the antimicrobial efficacy of metallic copper is not known. Here, we show that dry copper surfaces inactivate Candida albicans and Saccharomyces cerevisiae within minutes in a process called contact-mediated killing. Cellular copper ion homeostasis systems influenced the kinetics of contact-mediated killing in both organisms. Deregulated copper ion uptake through a hyperactive S. cerevisiae Ctr1p (ScCtr1p) copper uptake transporter in Saccharomyces resulted in faster inactivation of mutant cells than of wild-type cells. Similarly, lack of the C. albicans Crp1p (CaCrp1p) copper-efflux P-type ATPase or the metallothionein CaCup1p caused more-rapid killing of Candida mutant cells than of wild-type cells. Candida and Saccharomyces took up large quantities of copper ions as soon as they were in contact with copper surfaces, as indicated by inductively coupled plasma mass spectroscopy (ICP-MS) analysis and by the intracellular copper ion-reporting dye coppersensor-1. Exposure to metallic copper did not cause lethality through genotoxicity, deleterious action on a cell's genetic material, as indicated by a mutation assay with Saccharomyces. Instead, toxicity mediated by metallic copper surfaces targeted membranes in both yeast species. With the use of Live/Dead staining, onset of rapid and extensive cytoplasmic membrane damage was observed in cells from copper surfaces. Fluorescence microscopy using the indicator dye DiSBaC2(3) indicated that cell membranes were depolarized. Also, during contact-mediated killing, vacuoles first became enlarged and then disappeared from the cells. Lastly, in metallic copper-stressed yeasts, oxidative stress in the cytoplasm and in mitochondria was elevated. PMID:21097600

Plasmon-Mediated Solar Energy Conversion via Photocatalysis in Noble Metal/Semiconductor Composites.

PubMed

Wang, Mengye; Ye, Meidan; Iocozzia, James; Lin, Changjian; Lin, Zhiqun

2016-06-01

Plasmonics has remained a prominent and growing field over the past several decades. The coupling of various chemical and photo phenomenon has sparked considerable interest in plasmon-mediated photocatalysis. Given plasmonic photocatalysis has only been developed for a relatively short period, considerable progress has been made in improving the absorption across the full solar spectrum and the efficiency of photo-generated charge carrier separation. With recent advances in fundamental (i.e., mechanisms) and experimental studies (i.e., the influence of size, geometry, surrounding dielectric field, etc.) on plasmon-mediated photocatalysis, the rational design and synthesis of metal/semiconductor hybrid nanostructure photocatalysts has been realized. This review seeks to highlight the recent impressive developments in plasmon-mediated photocatalytic mechanisms (i.e., Schottky junction, direct electron transfer, enhanced local electric field, plasmon resonant energy transfer, and scattering and heating effects), summarize a set of factors (i.e., size, geometry, dielectric environment, loading amount and composition of plasmonic metal, and nanostructure and properties of semiconductors) that largely affect plasmonic photocatalysis, and finally conclude with a perspective on future directions within this rich field of research.

Intravascular local gene transfer mediated by protein-coated metallic stent.

PubMed

Yuan, J; Gao, R; Shi, R; Song, L; Tang, J; Li, Y; Tang, C; Meng, L; Yuan, W; Chen, Z

2001-10-01

To assess the feasibility, efficiency and selectivity of adenovirus-mediated gene transfer to local arterial wall by protein-coated metallic stent. A replication-defective recombinant adenovirus carrying the Lac Z reporter gene for nuclear-specific beta-galactosidase (Ad-beta gal) was used in this study. The coating for metallic stent was made by immersing it in a gelatin solution containing crosslinker. The coated stents were mounted on a 4.0 or 3.0 mm percutaneous transluminal coronary angioplasty (PTCA) balloon and submersed into a high-titer Ad-beta gal viral stock (2 x 10(10) pfu/ml) for 3 min, and then implanted into the carotid arteries in 4 mini-swines and into the left anterior descending branch of the coronary artery in 2 mini-swines via 8F large lumen guiding catheters. The animals were sacrificed 7 (n = 4), 14 (n = 1) and 21 (n = 1) days after implantation, respectively. The beta-galactosidase expression was assessed by X-gal staining. The results showed that the expression of transgene was detected in all animal. In 1 of carotid artery with an intact intima, the beta-gal expression was limited to endothelial cells. In vessels with denuded endothelium, gene expression was found in the sub-intima, media and adventitia. The transfection efficiency of medial smooth muscle cells was 38.6%. In 2 animals sacrificed 7 days after transfection, a microscopic examination of X-gal-stained samples did not show evidence of transfection in remote organs and arterial segments adjacent to the treated arterial site. Adenovirus-mediated arterial gene transfer to endothelial, smooth muscle cells and adventitia by protein-coated metallic stent is feasible. The transfection efficiency is higher. The coated stent may act as a good carrier of adenovirus-mediated gene transfer and have a potential to prevent restenosis following PTCA.

Transformational Leadership and Knowledge Sharing: Mediating Roles of Employee's Empowerment, Commitment, and Citizenship Behaviors

ERIC Educational Resources Information Center

Han, Seung Hyun; Seo, Gaeun; Yoon, Seung Won; Yoon, Dong-Yeol

2016-01-01

Purpose: The purpose of this paper is to empirically examine the fundamental process through which transformational leaders play a significant role in employees' knowledge sharing by investigating mediating roles of individual affects, particularly psychological empowerment, organizational commitment and organizational citizenship behavior (OCB).…

The effect of low-temperature transformation of mixtures of sewage sludge and plant materials on content, leachability and toxicity of heavy metals.

PubMed

Gondek, Krzysztof; Baran, Agnieszka; Kopeć, Michał

2014-12-01

The aim of the study was to determine the influence of the process of low-temperature transformation and the addition of plant material to sewage sludge diversifying the content of mobile forms of heavy metals and their ecotoxicity. The experimental design included: sewage sludge+rape straw, sewage sludge+wheat straw, sewage sludge+sawdust, sewage sludge+bark and sewage sludge with no addition. The mixtures were subjected to thermal transformation in a chamber furnace, under conditions without air. The procedure consisted of two stages: the first stage (130°C for 40 min) focused on drying the material, whereas in the second stage (200°C for 30 min) proper thermal transformation of materials took place. Thermal transformation of the materials, caused an increase in total contents of heavy metals in comparison to the material before transformation. From among elements, the cadmium content changed the most in materials after thermal transformation. As a result of thermal transformation, the content of water soluble form of the heavy metals decreased significantly in all the prepared mixtures. Low toxicity of the extracts from materials for Vibrio fischeri and Lepidium sativum was found in the research, regardless of transformation process. L. sativum showed higher sensitivity to heavy metals occurring in the studied extracts from materials than V. fischeri, evidence of which are the positive significant correlations between the content of metals and the inhibition of root growth of L. sativum. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies of transformational leadership in consumer service: leadership trust and the mediating-moderating role of cooperative conflict management.

PubMed

Yang, Yi-Feng

2012-02-01

This is the third in a series of studies evaluating how transformational leadership is associated with related variables such as job satisfaction, change commitment, leadership trust, cooperative conflict management, and market orientation. The present paper evaluates the effects of transformational leadership and cooperative conflict management along with their mediating and moderating of leadership trust in the life insurance industry for two sample groups, sales managers and sales employees. The main effect of leadership trust was mediated and moderated by cooperative conflict management. Cooperative conflict management made a more important contribution than transformational leadership or the moderating effect (interaction), but these three together were the most important variables predicting highest leadership trust. Transformational leadership has an indirect influence on leadership trust. This work summarizes the specific contribution and importance of building successful leadership trust associations with employees in relation to leadership and satisfaction with change commitment.

The development of coil short circuits when transformer windings become contaminated with metal-containing colloidal particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

L'vov, S. Yu.; Lyut'ko, E. O.; Bondareva, V. N.

The radiational-thermal development of coil short circuits due to the action of partial discharges of the first kind when the windings of transformers, autotransformers and shunting reactors become contaminated with metal-containing colloidal particles, formed in the transformer oil as a result of the interaction of the oil with the constructional materials (the copper of the windings, the iron of the tank, the core etc.) is considered. Acriterion of dangerous contamination of the coil insulation of the windings by metal-containing colloidal particles is proposed, namely, 3% of the mass content of copper and iron in it, which, if exceeded, may servemore » as a basis for recognizing the state of transformers, autotransformers and shunting reactors at a voltage of 110 kV and above the limit. It is shown that filters for continuously cleaning the oil play a considerable role in prolonging the life of transformer equipment.« less

Development of Protoporphyrinogen Oxidase as an Efficient Selection Marker for Agrobacterium tumefaciens-Mediated Transformation of Maize

PubMed Central

Li, Xianggan; Volrath, Sandy L.; Nicholl, David B.G.; Chilcott, Charles E.; Johnson, Marie A.; Ward, Eric R.; Law, Marcus D.

2003-01-01

In this article, we report the isolation of plant protoporphyrinogen oxidase (PPO) genes and the isolation of herbicide-tolerant mutants. Subsequently, an Arabidopsis double mutant (Y426M + S305L) was used to develop a selectable marker system for Agrobacterium tumefaciens-mediated transformation of maize (Zea mays) and to obtain multiple events tolerant to the PPO family of herbicides. Maize transformants were produced via butafenacil selection using a flexible light regime to increase selection pressure. Butafenacil selection per se did not change transgene copy number distribution relative to other selectable marker systems, but the most tolerant events identified in the greenhouse were more likely to contain multiple copies of the introduced mutant PPO gene. To date, more than 2,500 independent transgenic maize events have been produced using butafenacil selection. The high frequency of A. tumefaciens-mediated transformation via PPO selection enabled us to obtain single-copy transgenic maize lines tolerant to field levels of butafenacil. PMID:12972658

Development of an Agrobacterium-Mediated Stable Transformation Method for the Sensitive Plant Mimosa pudica

PubMed Central

Mano, Hiroaki; Fujii, Tomomi; Sumikawa, Naomi; Hiwatashi, Yuji; Hasebe, Mitsuyasu

2014-01-01

The sensitive plant Mimosa pudica has long attracted the interest of researchers due to its spectacular leaf movements in response to touch or other external stimuli. Although various aspects of this seismonastic movement have been elucidated by histological, physiological, biochemical, and behavioral approaches, the lack of reverse genetic tools has hampered the investigation of molecular mechanisms involved in these processes. To overcome this obstacle, we developed an efficient genetic transformation method for M. pudica mediated by Agrobacterium tumefaciens (Agrobacterium). We found that the cotyledonary node explant is suitable for Agrobacterium-mediated transformation because of its high frequency of shoot formation, which was most efficiently induced on medium containing 0.5 µg/ml of a synthetic cytokinin, 6-benzylaminopurine (BAP). Transformation efficiency of cotyledonary node cells was improved from almost 0 to 30.8 positive signals arising from the intron-sGFP reporter gene by using Agrobacterium carrying a super-binary vector pSB111 and stabilizing the pH of the co-cultivation medium with 2-(N-morpholino)ethanesulfonic acid (MES) buffer. Furthermore, treatment of the explants with the detergent Silwet L-77 prior to co-cultivation led to a two-fold increase in the number of transformed shoot buds. Rooting of the regenerated shoots was efficiently induced by cultivation on irrigated vermiculite. The entire procedure for generating transgenic plants achieved a transformation frequency of 18.8%, which is comparable to frequencies obtained for other recalcitrant legumes, such as soybean (Glycine max) and pea (Pisum sativum). The transgene was stably integrated into the host genome and was inherited across generations, without affecting the seismonastic or nyctinastic movements of the plants. This transformation method thus provides an effective genetic tool for studying genes involved in M. pudica movements. PMID:24533121

Development of an Agrobacterium-mediated stable transformation method for the sensitive plant Mimosa pudica.

PubMed

Mano, Hiroaki; Fujii, Tomomi; Sumikawa, Naomi; Hiwatashi, Yuji; Hasebe, Mitsuyasu

2014-01-01

The sensitive plant Mimosa pudica has long attracted the interest of researchers due to its spectacular leaf movements in response to touch or other external stimuli. Although various aspects of this seismonastic movement have been elucidated by histological, physiological, biochemical, and behavioral approaches, the lack of reverse genetic tools has hampered the investigation of molecular mechanisms involved in these processes. To overcome this obstacle, we developed an efficient genetic transformation method for M. pudica mediated by Agrobacterium tumefaciens (Agrobacterium). We found that the cotyledonary node explant is suitable for Agrobacterium-mediated transformation because of its high frequency of shoot formation, which was most efficiently induced on medium containing 0.5 µg/ml of a synthetic cytokinin, 6-benzylaminopurine (BAP). Transformation efficiency of cotyledonary node cells was improved from almost 0 to 30.8 positive signals arising from the intron-sGFP reporter gene by using Agrobacterium carrying a super-binary vector pSB111 and stabilizing the pH of the co-cultivation medium with 2-(N-morpholino)ethanesulfonic acid (MES) buffer. Furthermore, treatment of the explants with the detergent Silwet L-77 prior to co-cultivation led to a two-fold increase in the number of transformed shoot buds. Rooting of the regenerated shoots was efficiently induced by cultivation on irrigated vermiculite. The entire procedure for generating transgenic plants achieved a transformation frequency of 18.8%, which is comparable to frequencies obtained for other recalcitrant legumes, such as soybean (Glycine max) and pea (Pisum sativum). The transgene was stably integrated into the host genome and was inherited across generations, without affecting the seismonastic or nyctinastic movements of the plants. This transformation method thus provides an effective genetic tool for studying genes involved in M. pudica movements.

Agrobacterium-mediated transformation of maize (Zea mays) with Cre-lox site specific recombination cassettes in BIBAC vectors.

PubMed

Vega, Juan M; Yu, Weichang; Han, Fangpu; Kato, Akio; Peters, Eric M; Zhang, Zhanyuan J; Birchler, James A

2008-04-01

The Cre/loxP site-specific recombination system has been applied in various plant species including maize (Zea mays) for marker gene removal, gene targeting, and functional genomics. A BIBAC vector system was adapted for maize transformation with a large fragment of genetic material including a herbicide resistance marker gene, a 30 kb yeast genomic fragment as a marker for fluorescence in situ hybridization (FISH), and a 35S-lox-cre recombination cassette. Seventy-five transgenic lines were generated from Agrobacterium-mediated transformation of a maize Hi II line with multiple B chromosomes. Eighty-four inserts have been localized among all 10 A chromosome pairs by FISH using the yeast DNA probe together with a karyotyping cocktail. No inserts were found on the B chromosomes; thus a bias against the B chromosomes by the Agrobacterium-mediated transformation was revealed. The expression of a cre gene was confirmed in 68 of the 75 transgenic lines by a reporter construct for cre/lox mediated recombination. The placement of the cre/lox site-specific recombination system in many locations in the maize genome will be valuable materials for gene targeting and chromosome engineering.

Transformational leadership and safety performance among nurses: the mediating role of knowledge-related job characteristics.

PubMed

Lievens, Ilse; Vlerick, Peter

2014-03-01

To report the impact of transformational leadership on two dimensions of nurses' safety performance (i.e. safety compliance and safety participation) and to study the mediating role of knowledge-related job characteristics in this relationship. Safety performance refers to the behaviours that employees exhibit to adhere to safety guidelines and to promote health and safety at their workplace. Nurses' safety performance is a major challenge for healthcare settings, urging the need to identify the key determinants and psychological mechanisms that influence it. A cross-sectional survey study. The study was carried out in September 2010 in a large Belgian hospital. We used self-administered questionnaires; 152 nurses participated. The hypotheses were tested using hierarchical regression analyses. In line with our first hypothesis, the results show that transformational leadership exerted a significant positive impact on both dimensions of nurses' safety performance. This positive relation was mediated by knowledge-related job characteristics, supporting our second hypothesis. Head nurses' transformational leadership can enhance nurses' compliance with and participation in safety. Furthermore, transformational head nurses are able to influence the perception that their nurses have about the kind and amount of knowledge in their job, which can also lead to increases in both dimensions of nurses' safety performance. This study therefore demonstrates the key impact that transformational head nurses have, both directly and indirectly, on the safety performance of their nurses. © 2013 John Wiley & Sons Ltd.

Agrobacterium-mediated genetic transformation of yam (Dioscorea rotundata): an important tool for functional study of genes and crop improvement

PubMed Central

Nyaboga, Evans; Tripathi, Jaindra N.; Manoharan, Rajesh; Tripathi, Leena

2014-01-01

Although genetic transformation of clonally propagated crops has been widely studied as a tool for crop improvement and as a vital part of the development of functional genomics resources, there has been no report of any existing Agrobacterium-mediated transformation of yam (Dioscorea spp.) with evidence of stable integration of T-DNA. Yam is an important crop in the tropics and subtropics providing food security and income to over 300 million people. However, yam production remains constrained by increasing levels of field and storage pests and diseases. A major constraint to the development of biotechnological approaches for yam improvement has been the lack of an efficient and robust transformation and regeneration system. In this study, we developed an Agrobacterium-mediated transformation of Dioscorea rotundata using axillary buds as explants. Two cultivars of D. rotundata were transformed using Agrobacterium tumefaciens harboring the binary vectors containing selectable marker and reporter genes. After selection with appropriate concentrations of antibiotic, shoots were developed on shoot induction and elongation medium. The elongated antibiotic-resistant shoots were subsequently rooted on medium supplemented with selection agent. Successful transformation was confirmed by polymerase chain reaction, Southern blot analysis, and reporter genes assay. Expression of gusA gene in transgenic plants was also verified by reverse transcription polymerase chain reaction analysis. Transformation efficiency varied from 9.4 to 18.2% depending on the cultivars, selectable marker genes, and the Agrobacterium strain used for transformation. It took 3–4 months from Agro-infection to regeneration of complete transgenic plant. Here we report an efficient, fast and reproducible protocol for Agrobacterium-mediated transformation of D. rotundata using axillary buds as explants, which provides a useful platform for future genetic engineering studies in this economically important

A Fruiting Body Tissue Method for Efficient Agrobacterium-Mediated Transformation of Agaricus bisporus

PubMed Central

Chen, Xi; Stone, Michelle; Schlagnhaufer, Carl; Romaine, C. Peter

2000-01-01

We describe a modified Agrobacterium-mediated method for the efficient transformation of Agaricus bisporus. Salient features of this procedure include cocultivation of Agrobacterium and fruiting body gill tissue and use of a vector with a homologous promoter. This method offers new prospects for the genetic manipulation of this commercially important mushroom species. PMID:11010906

Agrobacterium-mediated genetic transformation of pineapple (Ananas comosus L., Merr.).

PubMed

Mhatre, Minal

2013-01-01

Pineapple (Ananas comosus L., Merr.) is a commercially important crop, grown in the tropical and subtropical regions. However, the crop is faced with postharvest damage and poor varietal and nutritional improvement. Being a vegetatively propagated crop, conventional breeding programs take longer time for genetic improvement, which may not necessarily successfully develop an improved cultivar. Hence, the genetic modification of pineapple is an alternative handy approach to improve pineapple. We have established an Agrobacterium-mediated transformation system using leaf bases from in vitro-grown pineapple plants. Being a monocot, acetosyringone is added to the culture medium for overnight growth of Agrobacterium and transformation to transfer a gene of interest MSI99 soybean ferritin. Leaf bases isolated from in vitro shoot cultures are treated with Agrobacterium suspension at two dilutions, 10× and 20×, for 30 min. Explants are subsequently blot dried and cultured on gelrite solidified hormone-free Pin1 medium for 2 days (cocultivation). Periodic transfer is first done to the regeneration medium (Pin1) containing cefotaxime for the suppression of Agrobacterium growth. The transformants are selected by culturing on Pin1 medium containing cefotaxime and kanamycin. Multiple shoots, regenerated in leaf bases, are further multiplied and individually rooted in the liquid RM medium amended with antibiotics to recover plants. Putative transformants are analyzed for transgene integration and expression using standard molecular biological methods of PCR, RT-PCR, and genomic Southern.

Alternative synthetic approaches for metal-organic frameworks: transformation from solid matters.

PubMed

Zhan, Guowu; Zeng, Hua Chun

2016-12-20

Developing economic and sustainable synthetic strategies for metal-organic frameworks (MOFs) is imperative for promoting MOF materials into large scale industrial use. Very recently, an alternative strategy for MOF synthesis by using solvent-insoluble "solid matters" as cation reservoirs and/or templates has been developed to accomplish this goal, in which the solid matters often refer to metals, metal oxides, hydroxides, carbonates, and so forth, but excluding the soluble metal salts which have been prevailingly used in MOF synthesis. Although most of the pioneering activities in this field have just started in the past 5 years, remarkable achievements have been made covering the synthesis, functionalization, positioning, and applications. A great number of MOFs in powder form, thin-films, or membranes, have been prepared through such solid-to-MOF transformations. This field is rapidly developing and expanding, and the number of related scientific publications has strikingly increased over the last few years. The aim of this review is to summarise the latest developments, highlight the present state-of-the-art, and also provide an overview for future research directions.

Characteristics and kinetic analysis of AQS transformation and microbial goethite reduction: Insight into “redox mediator-microbe-iron oxide” interaction process

DOE PAGES

Zhu, Weihuang; Shi, Mengran; Yu, Dan; ...

2016-03-29

Here, the characteristics and kinetics of redox transformation of a redox mediator, anthraquinone-2-sulfonate (AQS), during microbial goethite reduction by Shewanella decolorationis S12, a dissimilatory iron reduction bacterium (DIRB), were investigated to provide insights into “redox mediator-iron oxide” interaction in the presence of DIRB. Two pre-incubation reaction systems of the “strain S12-goethite” and the “strain S12-AQS” were used to investigate the dynamics of goethite reduction and AQS redox transformation. Results show that the concentrations of goethite and redox mediator, and the inoculation cell density all affect the characteristics of microbial goethite reduction, kinetic transformation between oxidized and reduced species of themore » redox mediator. Both abiotic and biotic reactions and their coupling regulate the kinetic process for “Quinone-Iron” interaction in the presence of DIRB. Our results provide some new insights into the characteristics and mechanisms of interaction among “quinone-DIRB- goethite” under biotic/abiotic driven.« less

Transformational Leadership, Transactional Contingent Reward, and Organizational Identification: The Mediating Effect of Perceived Innovation and Goal Culture Orientations.

PubMed

Xenikou, Athena

2017-01-01

Purpose: The aim of this research was to investigate the effect of transformational leadership and transactional contingent reward as complementary, but distinct, forms of leadership on facets of organizational identification via the perception of innovation and goal organizational values. Design/Methodology/Approach: Three studies were carried out implementing either a measurement of mediation or experimental-causal-chain design to test for the hypothesized effects. Findings: The measurement of mediation study showed that transformational leadership had a positive direct and indirect effect, via innovation value orientation, on cognitive identification, whereas transactional contingent reward was more strongly related to affective, rather than cognitive, identification, and goal orientation was a mediator of their link. The findings of the two experimental-causal-chain studies further supported the hypothesized effects. Transformational leadership was found to lead subordinates to perceive the culture as more innovative compared to transactional contingent reward, whereas transactional contingent reward led employees to perceive the culture as more goal, than innovation, oriented. Finally, innovation, compared to goal, value orientation increased cognitive identification, while goal orientation facilitated affective, rather than cognitive, identification. Implications: The practical implications involve the development of strategies organizations can apply, such as leadership training programs, to strengthen their ties with their employees, which, in turn, may have a positive impact on in-role, as well as extra-role, behaviors. Originality/Value: The originality of this research concerns the identification of distinct mechanisms explaining the effect of transformational leadership and transactional contingent reward on cognitive and affective identification applying an organizational culture perspective and a combination of measurement and causal mediation designs.

Mineral transformations during the dissolution of uranium ore minerals by dissimilatory metal-reducing bacteria

NASA Astrophysics Data System (ADS)

Glasauer, S.; Weidler, P.; Fakra, S.; Tyliszczak, T.; Shuh, D.

2011-12-01

Carnotite minerals [X2(UO2)2(VO4)2]; X = K, Ca, Ba, Mn, Na, Cu or Pb] form the major ore of uranium in the Colorado Plateau. These deposits are highly oxidized and contain U(VI) and V(IV). The biotransformation of U(VI) bound in carnotite by bacteria during dissimilatory metal reduction presents a complex puzzle in mineral chemistry. Both U(VI) and V(V) can be respired by metal reducing bacteria, and the mineral structure can change depending on the associated counterion. We incubated anaerobic cultures of S. putrefaciens CN32 with natural carnotite minerals from southeastern Utah in a nutrient-limited defined medium. Strain CN32 is a gram negative bacterium and a terrestrial isolate from New Mexico. The mineral and metal transformations were compared to a system that contained similar concentrations of soluble U(VI) and V(V). Electron (SEM, TEM) microscopies and x-ray spectromicroscopy (STXM) were used in conjunction with XRD to track mineral changes, and bacterial survival was monitored throughout the incubations. Slow rates of metal reduction over 10 months for the treatment with carnotite minerals revealed distinct biotic and abiotic processes, providing insight on mineral transformation and bacteria-metal interactions. The bacteria existed as small flocs or individual cells attached to the mineral phase, but did not adsorb soluble U or V, and accumulated very little of the biominerals. Reduction of mineral V(V) necessarily led to a dismantling of the carnotite structure. Bioreduction of V(V) by CN32 contributed small but profound changes to the mineral system, resulting in new minerals. Abiotic cation exchange within the carnotite group minerals induced the rearrangement of the mineral structures, leading to further mineral transformation. In contrast, bacteria survival was poor for treatments with soluble U(VI) and V(V), although both metals were reduced completely and formed solid UO2 and VO2; we also detected V(III). For these treatments, the bacteria

Genetic transformation of Fusarium avenaceum by Agrobacterium tumefaciens mediated transformation and the development of a USER-Brick vector construction system

PubMed Central

2014-01-01

Background The plant pathogenic and saprophytic fungus Fusarium avenaceum causes considerable in-field and post-field losses worldwide due to its infections of a wide range of different crops. Despite its significant impact on the profitability of agriculture production and a desire to characterize the infection process at the molecular biological level, no genetic transformation protocol has yet been established for F. avenaceum. In the current study, it is shown that F. avenaceum can be efficiently transformed by Agrobacterium tumefaciens mediated transformation. In addition, an efficient and versatile single step vector construction strategy relying on Uracil Specific Excision Reagent (USER) Fusion cloning, is developed. Results The new vector construction system, termed USER-Brick, is based on a limited number of PCR amplified vector fragments (core USER-Bricks) which are combined with PCR generated fragments from the gene of interest. The system was found to have an assembly efficiency of 97% with up to six DNA fragments, based on the construction of 55 vectors targeting different polyketide synthase (PKS) and PKS associated transcription factor encoding genes in F. avenaceum. Subsequently, the ΔFaPKS3 vector was used for optimizing A. tumefaciens mediated transformation (ATMT) of F. avenaceum with respect to six variables. Acetosyringone concentration, co-culturing time, co-culturing temperature and fungal inoculum were found to significantly impact the transformation frequency. Following optimization, an average of 140 transformants per 106 macroconidia was obtained in experiments aimed at introducing targeted genome modifications. Targeted deletion of FaPKS6 (FA08709.2) in F. avenaceum showed that this gene is essential for biosynthesis of the polyketide/nonribosomal compound fusaristatin A. Conclusion The new USER-Brick system is highly versatile by allowing for the reuse of a common set of building blocks to accommodate seven different types of genome

Improved production of transgenic Dioscorea zingiberensis (Dioscoreaceae) by Agrobacterium tumefaciens-mediated transformation.

PubMed

Shi, L; Fan, J Q; Hu, C G; Luo, J; Yao, J L

2012-02-03

The establishment of high-efficiency Agrobacterium-mediated transformation techniques could improve the production of Dioscorea zingiberensis, a medicinal species with a high diosgenin content. We co-cultivated embryogenic calli induced from mature seeds with A. tumefaciens strain EHA105. A binary vector, pCAMBIA1381, which contains the gfp and hpt genes under the control of the ubiquitin promoter and the CaMV 35S promoter, respectively, was used for transformation. Pre-culture, basic medium, acetosyringone, and bacterial density were evaluated to establish the most efficient protocol. The optimal conditions consisted of MS medium without CaCl(2) for pre- and co-cultivation, three days for pre-culture, addition of 200 μM AS, and an OD(600) of 0.5. The transgenic plants grown under selection were confirmed by PCR analysis and Southern blot analysis. This protocol produced transgenic D. zingiberensis plants in seven months, with a transformation efficiency of 6%.

Linking transformational leadership to nurses' extra-role performance: the mediating role of self-efficacy and work engagement.

PubMed

Salanova, Marisa; Lorente, Laura; Chambel, Maria J; Martínez, Isabel M

2011-10-01

This paper is a report of a social cognitive theory-guided study about the link between supervisors' transformational leadership and staff nurses' extra-role performance as mediated by nurse self-efficacy and work engagement. Past research has acknowledged the positive influence that transformational leaders have on employee (extra-role) performance. However, less is known about the psychological mechanisms that may explain the links between transformational leaders and extra-role performance, which encompasses behaviours that are not considered formal job requirements, but which facilitate the smooth functioning of the organization as a social system. Seventeen supervisors evaluated nurses' extra-role performance, the data generating a sample consisting of 280 dyads. The nurses worked in different health services in a large Portuguese hospital and the participation rate was 76·9% for nurses and 100% for supervisors. Data were collected during 2009. A theory-driven model of the relationships between transformation leadership, self-efficacy, work engagement and nurses' extra-role performance was tested using Structural Equation Modelling. Data analysis revealed a full mediation model in which transformational leadership explained extra-role performance through self-efficacy and work engagement. A direct relationship between transformational leadership and work engagement was also found. Nurses' supervisors with a transformational leadership style enhance different 'extra-role' performance in nurses and this increases hospital efficacy. They do so by establishing a sense of self-efficacy but also by amplifying their levels of engagement in the workplace. © 2011 Blackwell Publishing Ltd.

Transformation of metal-organic frameworks for molecular sieving membranes

PubMed Central

Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

2016-01-01

The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

Plasmon‐Mediated Solar Energy Conversion via Photocatalysis in Noble Metal/Semiconductor Composites

PubMed Central

Wang, Mengye; Ye, Meidan; Iocozzia, James

2016-01-01

Plasmonics has remained a prominent and growing field over the past several decades. The coupling of various chemical and photo phenomenon has sparked considerable interest in plasmon‐mediated photocatalysis. Given plasmonic photocatalysis has only been developed for a relatively short period, considerable progress has been made in improving the absorption across the full solar spectrum and the efficiency of photo‐generated charge carrier separation. With recent advances in fundamental (i.e., mechanisms) and experimental studies (i.e., the influence of size, geometry, surrounding dielectric field, etc.) on plasmon‐mediated photocatalysis, the rational design and synthesis of metal/semiconductor hybrid nanostructure photocatalysts has been realized. This review seeks to highlight the recent impressive developments in plasmon‐mediated photocatalytic mechanisms (i.e., Schottky junction, direct electron transfer, enhanced local electric field, plasmon resonant energy transfer, and scattering and heating effects), summarize a set of factors (i.e., size, geometry, dielectric environment, loading amount and composition of plasmonic metal, and nanostructure and properties of semiconductors) that largely affect plasmonic photocatalysis, and finally conclude with a perspective on future directions within this rich field of research. PMID:27818901

Effect of selection agents to Chrysanthemum (Chrysanthemum morifolium) callus growth after Agrobacterium-mediated genetic transformation

NASA Astrophysics Data System (ADS)

Sjahril, R.; Jamaluddin, I.; Nadir, M.; Asman; Dungga, N. E.

2018-05-01

Genetic transformation mediated by Agrobacterium tumefaciens requires an efficient selection method for successful progress of transformation. This study aims to determine the concentration and kind of antibiotics and selection agents used during transformation to formulate standard protocol of chrysanthemum in the process of propagating disease resistant Chrysanthemum mediated by Agrobacterium tumefaciens EHA105 (pEKB-WD). The experiments were performed by planting chrysanthemum explants leaf cutting (5 mm diameter on NAA medium 2 mg L-1 BAP 2 mg L-1) with addition of Kanamycin: 25, 50, 100, 150 and 200 (mg L-1); Hygromycin: 5, 10, 25, 50 and 75 (mg L-1); Paromomycin: 10, 25, 50, 75 and 100 (mg L-1). Experiment was arranged in a Completely Randomized Design (CRD). Each treatment was repeated five times thus 75 bottles of culture were used; each bottle consists of 5 pieces of leaf cuttings, resulted in total of 375 pieces. The results showed that selection agent had a critical value for Hygromycin 25 mg L-1 and Kanamycin 100 mg L-1 which can make explant experienced necrosis better than Paromomycin. Paromomycin at 100 mg L-1 was only able to kill explant’s periphery. Remained callus stayed fresh more than 50% so that when used as the selection agent could produce more escape cell. The optimum transformation with concentration of 10% Agrobacterium (vol/vol) with 30 minutes co-cultivation can produce more efficient transformed callus. Considering the high price of Hygromycin, it was best to use Kanamycin as selective agents.

Geomycology: biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation.

PubMed

Gadd, Geoffrey M

2007-01-01

The study of the role that fungi have played and are playing in fundamental geological processes can be termed 'geomycology' and this article seeks to emphasize the fundamental importance of fungi in several key areas. These include organic and inorganic transformations and element cycling, rock and mineral transformations, bioweathering, mycogenic mineral formation, fungal-clay interactions, metal-fungal interactions, and the significance of such processes in the environment and their relevance to areas of environmental biotechnology such as bioremediation. Fungi are intimately involved in biogeochemical transformations at local and global scales, and although such transformations occur in both aquatic and terrestrial habitats, it is the latter environment where fungi probably have the greatest influence. Within terrestrial aerobic ecosystems, fungi may exert an especially profound influence on biogeochemical processes, particularly when considering soil, rock and mineral surfaces, and the plant root-soil interface. The geochemical transformations that take place can influence plant productivity and the mobility of toxic elements and substances, and are therefore of considerable socio-economic relevance, including human health. Of special significance are the mutualistic symbioses, lichens and mycorrhizas. Some of the fungal transformations discussed have beneficial applications in environmental biotechnology, e.g. in metal leaching, recovery and detoxification, and xenobiotic and organic pollutant degradation. They may also result in adverse effects when these processes are associated with the degradation of foodstuffs, natural products, and building materials, including wood, stone and concrete. It is clear that a multidisciplinary approach is essential to understand fully all the phenomena encompassed within geomycology, and it is hoped that this review will serve to catalyse further research, as well as stimulate interest in an area of mycology of global

Agrobacterium-mediated genetic transformation of Coffea arabica (L.) is greatly enhanced by using established embryogenic callus cultures

PubMed Central

2011-01-01

Background Following genome sequencing of crop plants, one of the main challenges today is determining the function of all the predicted genes. When gene validation approaches are used for woody species, the main obstacle is the low recovery rate of transgenic plants from elite or commercial cultivars. Embryogenic calli have frequently been the target tissue for transformation, but the difficulty in producing or maintaining embryogenic tissues is one of the main problems encountered in genetic transformation of many woody plants, including Coffea arabica. Results We identified the conditions required for successful long-term proliferation of embryogenic cultures in C. arabica and designed a highly efficient and reliable Agrobacterium tumefaciens-mediated transformation method based on these conditions. The transformation protocol with LBA1119 harboring pBin 35S GFP was established by evaluating the effect of different parameters on transformation efficiency by GFP detection. Using embryogenic callus cultures, co-cultivation with LBA1119 OD600 = 0.6 for five days at 20 °C enabled reproducible transformation. The maintenance conditions for the embryogenic callus cultures, particularly a high auxin to cytokinin ratio, the age of the culture (optimum for 7-10 months of proliferation) and the use of a yellow callus phenotype, were the most important factors for achieving highly efficient transformation (> 90%). At the histological level, successful transformation was related to the number of proembryogenic masses present. All the selected plants were proved to be transformed by PCR and Southern blot hybridization. Conclusion Most progress in increasing transformation efficiency in coffee has been achieved by optimizing the production conditions of embryogenic cultures used as target tissues for transformation. This is the first time that a strong positive effect of the age of the culture on transformation efficiency was demonstrated. Our results make Agrobacterium-mediated

Transformational Leadership, Transactional Contingent Reward, and Organizational Identification: The Mediating Effect of Perceived Innovation and Goal Culture Orientations

PubMed Central

Xenikou, Athena

2017-01-01

Purpose: The aim of this research was to investigate the effect of transformational leadership and transactional contingent reward as complementary, but distinct, forms of leadership on facets of organizational identification via the perception of innovation and goal organizational values. Design/Methodology/Approach: Three studies were carried out implementing either a measurement of mediation or experimental-causal-chain design to test for the hypothesized effects. Findings: The measurement of mediation study showed that transformational leadership had a positive direct and indirect effect, via innovation value orientation, on cognitive identification, whereas transactional contingent reward was more strongly related to affective, rather than cognitive, identification, and goal orientation was a mediator of their link. The findings of the two experimental-causal-chain studies further supported the hypothesized effects. Transformational leadership was found to lead subordinates to perceive the culture as more innovative compared to transactional contingent reward, whereas transactional contingent reward led employees to perceive the culture as more goal, than innovation, oriented. Finally, innovation, compared to goal, value orientation increased cognitive identification, while goal orientation facilitated affective, rather than cognitive, identification. Implications: The practical implications involve the development of strategies organizations can apply, such as leadership training programs, to strengthen their ties with their employees, which, in turn, may have a positive impact on in-role, as well as extra-role, behaviors. Originality/Value: The originality of this research concerns the identification of distinct mechanisms explaining the effect of transformational leadership and transactional contingent reward on cognitive and affective identification applying an organizational culture perspective and a combination of measurement and causal mediation designs

Defect-mediated magnetism of transition metal doped zinc oxide thin films

NASA Astrophysics Data System (ADS)

Roberts, Bradley Kirk

Magnetism in transition metal doped wide band-gap materials is of interest to further the fundamental science of materials and future spintronics applications. Large inter-dopant separations require mediation of ferromagnetism by some method; carrier-mediated mechanisms are typically applicable to dilute magnetic semiconductors with low Curie temperatures. Dilute magnetic oxides, commonly with poor conductivity and TC above room temperature, cannot be described within this theory. Recent experiment and theory developments suggest that ferromagnetic exchange in these materials can be mediated by defects. This research includes experimental results justifying and developing this approach. Thin films of Cr doped ZnO (band gap ˜3.3 eV) were deposited with several processing variations to enhance the effects of either 0-dimensional (vacancy, hydrogen-related defect) or two-dimensional defects (surface/interface) and thereby affect magnetism and conductivity. We observe surface magnetism in dielectric thin films of oxygen-saturated ZnO:Cr with spontaneous magnetic moment and conductance dropping approximately exponentially with increasing thickness. Uniform defect concentrations would not result in such magnetic ordering behavior indicating that magnetism is mediated either by surface defects or differing concentrations of point defects near the surface. Polarized neutron reflectivity profiling confirms a magnetically active region of ˜8 nm at the film surface. Hydrogen is notoriously present as a defect and carrier dopant in ZnO, and artificial introduction of hydrogen in dielectric ZnO:Cr films results in varying electronic and magnetic behavior. Free carriers introduced with hydrogen doping are not spin-polarized requiring an alternative explanation for ferromagnetism. We find from positron annihilation spectroscopy measurements that hydrogen doping increases the concentration of an altered VZn-related defect (a preliminary interpretation) throughout the film, which

In situ-generated metal oxide catalyst during CO oxidation reaction transformed from redox-active metal-organic framework-supported palladium nanoparticles

PubMed Central

2012-01-01

The preparation of redox-active metal-organic framework (ra-MOF)-supported Pd nanoparticles (NPs) via the redox couple-driven method is reported, which can yield unprotected metallic NPs at room temperature within 10 min without the use of reducing agents. The Pd@ra-MOF has been exploited as a precursor of an active catalyst for CO oxidation. Under the CO oxidation reaction condition, Pd@ra-MOF is transformed into a PdOx-NiOy/C nanocomposite to generate catalytically active species in situ, and the resultant nanocatalyst shows sustainable activity through synergistic stabilization. PMID:22898143

Agrobacterium tumefaciens-mediated transformation for investigating pathogenicity genes of the phytopathogenic fungus Colletotrichum sansevieriae.

PubMed

Nakamura, Masayuki; Kuwahara, Hideto; Onoyama, Keisuke; Iwai, Hisashi

2012-08-01

Agrobacterium tumefaciens-mediated transformation (AtMT) has become a common technique for DNA transformation of yeast and filamentous fungi. In this study, we first established a protocol of AtMT for the phytopathogenic fungus Colletotrichum sansevieriae. Binary T-DNA vector containing the hygromycin B phosphotransferase gene controlled by the Aspergillus nidulans gpdA promoter and the trpC terminator was constructed with pCAMBIA0380 and used with three different strains LBA4404, GV3101, and GV2260 of A. tumefaciens. Transformants were most effectively obtained when GV2260 and C. sansevieriae Sa-1-2 were co-cultivated; there were about 320 transformants per 10(6) spores. When 1,048 transformants were inoculated on Sansevieria trifasciata, three transformants were found to have completely lost their pathogenicity and two transformants displayed reduced pathogenicity. All of the five transformants had a single copy of T-DNA in their genomes. The three pathogenicity-deficient transformants were subjected to thermal asymmetric interlaced polymerase chain reaction and the reaction allowed us to amplify the sequences flanking the left and/or right borders. The flanking sequences of the two transformants, M154 and M875, showed no homology to any sequences in databases, but the sequences of M678 contained motifs of alpha-1,3-glucan synthase, suggesting that the gene might contribute to the pathogenicity of C. sansevieriae. This study describes a useful method for investigating pathogenicity genes in C. sansevieriae.

Extracellular Saccharide-Mediated Reduction of Au3+ to Gold Nanoparticles: New Insights for Heavy Metals Biomineralization on Microbial Surfaces.

PubMed

Kang, Fuxing; Qu, Xiaolei; Alvarez, Pedro J J; Zhu, Dongqiang

2017-03-07

Biomineralization is a critical process controlling the biogeochemical cycling, fate, and potential environmental impacts of heavy metals. Despite the indispensability of extracellular polymeric substances (EPS) to microbial life and their ubiquity in soil and aquatic environments, the role played by EPS in the transformation and biomineralization of heavy metals is not well understood. Here, we used gold ion (Au 3+ ) as a model heavy metal ion to quantitatively assess the role of EPS in biomineralization and discern the responsible functional groups. Integrated spectroscopic analyses showed that Au 3+ was readily reduced to zerovalent gold nanoparticles (AuNPs, 2-15 nm in size) in aqueous suspension of Escherichia coli or dissolved EPS extracted from microbes. The majority of AuNPs (95.2%) was formed outside Escherichia coli cells, and the removal of EPS attached to cells pronouncedly suppressed Au 3+ reduction, reflecting the predominance of the extracellular matrix in Au 3+ reduction. XPS, UV-vis, and FTIR analyses corroborated that Au 3+ reduction was mediated by the hemiacetal groups (aldehyde equivalents) of reducing saccharides of EPS. Consistently, the kinetics of AuNP formation obeyed pseudo-second-order reaction kinetics with respect to the concentrations of Au 3+ and the hemiacetal groups in EPS, with minimal dependency on the source of microbial EPS. Our findings indicate a previously overlooked, universally significant contribution of EPS to the reduction, mineralization, and potential detoxification of metal species with high oxidation state.

Homeologous plastid DNA transformation in tobacco is mediated by multiple recombination events.

PubMed Central

Kavanagh, T A; Thanh, N D; Lao, N T; McGrath, N; Peter, S O; Horváth, E M; Dix, P J; Medgyesy, P

1999-01-01

Efficient plastid transformation has been achieved in Nicotiana tabacum using cloned plastid DNA of Solanum nigrum carrying mutations conferring spectinomycin and streptomycin resistance. The use of the incompletely homologous (homeologous) Solanum plastid DNA as donor resulted in a Nicotiana plastid transformation frequency comparable with that of other experiments where completely homologous plastid DNA was introduced. Physical mapping and nucleotide sequence analysis of the targeted plastid DNA region in the transformants demonstrated efficient site-specific integration of the 7.8-kb Solanum plastid DNA and the exclusion of the vector DNA. The integration of the cloned Solanum plastid DNA into the Nicotiana plastid genome involved multiple recombination events as revealed by the presence of discontinuous tracts of Solanum-specific sequences that were interspersed between Nicotiana-specific markers. Marked position effects resulted in very frequent cointegration of the nonselected peripheral donor markers located adjacent to the vector DNA. Data presented here on the efficiency and features of homeologous plastid DNA recombination are consistent with the existence of an active RecA-mediated, but a diminished mismatch, recombination/repair system in higher-plant plastids. PMID:10388829

Hypothesis test of mediation effect in causal mediation model with high-dimensional continuous mediators.

PubMed

Huang, Yen-Tsung; Pan, Wen-Chi

2016-06-01

Causal mediation modeling has become a popular approach for studying the effect of an exposure on an outcome through a mediator. However, current methods are not applicable to the setting with a large number of mediators. We propose a testing procedure for mediation effects of high-dimensional continuous mediators. We characterize the marginal mediation effect, the multivariate component-wise mediation effects, and the L2 norm of the component-wise effects, and develop a Monte-Carlo procedure for evaluating their statistical significance. To accommodate the setting with a large number of mediators and a small sample size, we further propose a transformation model using the spectral decomposition. Under the transformation model, mediation effects can be estimated using a series of regression models with a univariate transformed mediator, and examined by our proposed testing procedure. Extensive simulation studies are conducted to assess the performance of our methods for continuous and dichotomous outcomes. We apply the methods to analyze genomic data investigating the effect of microRNA miR-223 on a dichotomous survival status of patients with glioblastoma multiforme (GBM). We identify nine gene ontology sets with expression values that significantly mediate the effect of miR-223 on GBM survival. © 2015, The International Biometric Society.

XK-related protein 5 (XKR5) is a novel negative regulator of KIT/D816V-mediated transformation.

PubMed

Sun, Jianmin; Thingholm, Tine; Højrup, Peter; Rönnstrand, Lars

2018-06-18

In order to investigate the molecular mechanisms by which the oncogenic mutant KIT/D816V causes transformation of cells, we investigated proteins that selectively bind KIT/D816V, but not wild-type KIT, as potential mediators of transformation. By mass spectrometry several proteins were identified, among them a previously uncharacterized protein denoted XKR5 (XK-related protein 5), which is related to the X Kell blood group proteins. We could demonstrate that interaction between XKR5 and KIT/D816V leads to phosphorylation of XKR5 at Tyr 369, Tyr487, and Tyr 543. Tyrosine phosphorylated XKR5 acts as a negative regulator of KIT signaling, which leads to downregulation of phosphorylation of ERK, AKT, and p38. This led to reduced proliferation and colony forming capacity in semi-solid medium. Taken together, our data demonstrate that XKR5 is a novel type of negative regulator of KIT-mediated transformation.

Peculiarities of structural transformations in metal nanoparticles at high speed collisions

NASA Astrophysics Data System (ADS)

Zolnikov, K. P.; Kryzhevich, D. S.; Korchuganov, A. V.

2018-01-01

A molecular dynamics simulation of nanosized particle collision under the electrical explosion of metal wires of different types was conducted. Interatomic interactions were described on the base of the embedded atom method. Used potentials allowed describing with high accuracy many mechanical and physical properties which are very important for the simulations of nanoparticle collisions with high velocities. The dynamics of the nanosized particle formation at the electric pulse explosion of metal wires of different types was studied. Features of particle collisions on the example of nanoscale particles of copper and nickel, whose velocities varied from 50 to 1500 m/s were investigated. The peculiarities of structural transformations in the colliding particles depending on the velocity of collision were determined. The intervals of collision velocities in which interaction between particles is elastic or leads to the formation of structural defects or melting were calculated. The analysis of the structure and distribution of chemical elements over the cross section of the particles which were synthesized under simultaneous explosions of different metal wires was carried out.

Effects of metals on the transformation of hexabromocyclododecane (HBCD) in solvents: implications for solvent-based recycling of brominated flame retardants.

PubMed

Zhong, Yin; Peng, Ping'an; Yu, Zhiqiang; Deng, Haopeng

2010-09-01

The management of electronic wastes (e-wastes) has become a global issue as it may release large quantities of hazardous materials such as heavy metals and brominated flame retardants (BFRs) to the environment. Solvent-based recycling is a newly developed, efficient and environmentally beneficial technology for the removal or recovery of BFRs from e-wastes. However, little is known about the behavior of BFRs in the solvents and to what extent they may be affected by co-existing heavy metals. This study quantified the rates of transformation of hexabromocyclododecane (HBCD), a widely used BFR, in the presence of different solvents (i.e. acetone, methanol or toluene) and metals (i.e. Ni, Cu, Zn, Fe or Al). Our experimental results showed that less than 20% of HBCD was transformed in all pure solvent systems within 24h at 50 degrees C. The presence of Ni greatly increased the transformation of HBCD (45-99%) in these solvent systems, whereas other metals had little or no effect on extraction process. The kinetics study showed that transformation of HBCD in Ni-containing systems followed pseudo-first-order kinetics and that the highest transformation rate constant (1.2+/-0.1h(-1)) of HBCD was recorded in the Ni+acetone system. The formation of HBr and pentabromocyclododecene in the acetone+Ni system suggested that transformation of HBCD proceeded via dehydrobromination. Collectively, these results indicated that acetone should not be applied in the recycling or extraction of HBCD from Ni-rich e-wastes, as debromination of HBCD may occur during these processes, even at mild extraction temperatures. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

[Analysis of heavy-metal-mediated disease and development of a novel remediation system based on fieldwork and experimental research].

PubMed

Yajima, Ichiro; Zou, Cunchao; Li, Xiang; Nakano, Chizuru; Omata, Yasuhiro; Kumasaka, Mayuko Y

2015-01-01

Heavy-metal pollution occurs in various environments, including water, air and soil, and has serious effects on human health. Since heavy-metal pollution in drinking water causes various diseases including skin cancer, it has become a global problem worldwide. However, there is limited information on the mechanism of development of heavy-metal-mediated disease. We performed both fieldwork and experimental studies to elucidate the levels of heavy-metal pollution and mechanisms of development of heavy-metal-related disease and to develop a novel remediation system. Our fieldwork in Bangladesh, Vietnam and Malaysia demonstrated that drinking well water in these countries was polluted with high concentrations of several heavy metals including arsenic, barium, iron and manganese. Our experimental studies based on the data from our fieldwork demonstrated that these heavy metals caused skin cancer and hearing loss. Further experimental studies resulted in the development of a novel remediation system with which toxic heavy metals were absorbed from polluted drinking water. Implementation of both fieldwork and experimental studies is important for prediction, prevention and therapy of heavy-metal-mediated diseases.

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

DOE PAGES

Berman, Diana; Deshmukh, Sanket; Narayanan, Badri; ...

2016-07-04

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the processmore » can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.« less

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berman, Diana; Deshmukh, Sanket; Narayanan, Badri

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the processmore » can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.« less

[Effects of stabilization treatment on migration and transformation of heavy metals in mineral waste residues].

PubMed

Zhao, Shu-Hua; Chen, Zhi-Liang; Zhang, Tai-Ping; Pan, Wei-Bin; Peng, Xiao-Chun; Che, Rong; Ou, Ying-Juan; Lei, Guo-Jian; Zhou, Ding

2014-04-01

Different forms of heavy metals in soil will produce different environmental effects, and will directly influence the toxicity, migration and bioavailability of heavy metals. This study used lime, fly ash, dried sludge, peanut shells as stabilizers in the treatment of heavy metals in mineral waste residues. Morphological analyses of heavy metal, leaching experiments, potted plant experiments were carried out to analyze the migration and transformation of heavy metals. The results showed that after adding stabilizers, the pH of the acidic mineral waste residues increased to more than neutral, and the organic matter content increased significantly. The main existing forms of As, Pb, and Zn in the mineral waste residues were the residual. The contents of exchangeable and organic matter-bound As decreased by 65.6% and 87.7% respectively after adding fly ash, dried sludge and peanut shells. Adding lime, fly ash and peanut shells promoted the transformation of As from the Fe-Mn oxide-bound to the carbonate-bound, and adding lime and fly ash promoted the transformation of Pb and Zn from the exchangeable, Fe-Mn oxide-bound, organic matter-bound to the residual. After the early stage of the stabilization treatment, the contents of As, Pb and Zn in the leachate had varying degrees of decline, and adding peanut shells could reduce the contents of As, Pb and Zn in the leachate further. Among them, the content of As decreased most significantly after treatment with fly ash, dried sludge and peanut shells, with a decline of 57.4%. After treatment with lime, fly ash and peanut shells, the content of Zn decreased most significantly, by 24.9%. The addition of stabilizers was advantageous to the germination and growth of plants. The combination of fly ash, dried sludge and peanut shell produced the best effect, and the Vetiveria zizanioides germination rate reached 76% in the treated wasted mineral residues.

Delineation of First-Order Elastic Property Closures for Hexagonal Metals Using Fast Fourier Transforms

PubMed Central

Landry, Nicholas W.; Knezevic, Marko

2015-01-01

Property closures are envelopes representing the complete set of theoretically feasible macroscopic property combinations for a given material system. In this paper, we present a computational procedure based on fast Fourier transforms (FFTs) for delineation of elastic property closures for hexagonal close packed (HCP) metals. The procedure consists of building a database of non-zero Fourier transforms for each component of the elastic stiffness tensor, calculating the Fourier transforms of orientation distribution functions (ODFs), and calculating the ODF-to-elastic property bounds in the Fourier space. In earlier studies, HCP closures were computed using the generalized spherical harmonics (GSH) representation and an assumption of orthotropic sample symmetry; here, the FFT approach allowed us to successfully calculate the closures for a range of HCP metals without invoking any sample symmetry assumption. The methodology presented here facilitates for the first time computation of property closures involving normal-shear coupling stiffness coefficients. We found that the representation of these property linkages using FFTs need more terms compared to GSH representations. However, the use of FFT representations reduces the computational time involved in producing the property closures due to the use of fast FFT algorithms. Moreover, FFT algorithms are readily available as opposed to GSH codes. PMID:28793566

Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Zhihui; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049; Zhang, Feng

2015-04-15

By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, Hg{sup 2+} are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface areamore » up to 373 m{sup 2}/g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, and Hg{sup 2+}, respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater. - Graphical abstract: Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO. - Highlights: • We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites. • Introduction of PD layer increases metal ions adsorption capacity. • PEI–PD/RGO aerogel exhibited a superior adsorption performance. • PEI–PD/RGO aerogel can be recycled several times in a simple way.« less

Does self-efficacy mediate the relationship between transformational leadership behaviours and healthcare workers' sleep quality? A longitudinal study.

PubMed

Munir, Fehmidah; Nielsen, Karina

2009-09-01

This paper is a report of a study conducted to investigate the longitudinal relationship between transformational leadership behaviours and employees' sleep quality, and the mediating effects of self-efficacy. Although there is evidence for the influential role of transformational leadership on health outcomes, researchers have used either attitude outcomes (e.g. job satisfaction) or softer health measures, such as general well-being. Specific measures of well-being such as sleep quality have not been used, despite its association with working conditions. A longitudinal design was used to collect data from Danish healthcare workers at time 1 in 2005 (n = 447) and 18 months later at time 2 in 2007 (n = 274). Structural equation modelling was used to investigate the relationships between transformational leadership, self-efficacy and sleep quality at both time points independently (cross-sectionally) and longitudinally. For all constructs, time 2 measures were influenced by the baseline level. Direct relationships between transformational leadership and sleep quality were found. This relationship was negative cross-sectionally at both time points, but positive between baseline and follow-up. The relationship between leadership and employees' sleep quality was not mediated by employees' self-efficacy. Our results indicate that training managers in transformational leadership behaviours may have a positive impact on healthcare workers' health over time. However, more research is needed to examine the mechanisms by which transformational leadership brings about improved sleep quality; self-efficacy was not found to be the explanation.

Altering Genomic Integrity: Heavy Metal Exposure Promotes Transposable Element-Mediated Damage.

PubMed

Morales, Maria E; Servant, Geraldine; Ade, Catherine; Roy-Engel, Astrid M

2015-07-01

Maintenance of genomic integrity is critical for cellular homeostasis and survival. The active transposable elements (TEs) composed primarily of three mobile element lineages LINE-1, Alu, and SVA comprise approximately 30% of the mass of the human genome. For the past 2 decades, studies have shown that TEs significantly contribute to genetic instability and that TE-caused damages are associated with genetic diseases and cancer. Different environmental exposures, including several heavy metals, influence how TEs interact with its host genome increasing their negative impact. This mini-review provides some basic knowledge on TEs, their contribution to disease, and an overview of the current knowledge on how heavy metals influence TE-mediated damage.

Bioavailable transition metals in particulate matter mediate cardiopulmonary injury in healthy and compromised animal models.

PubMed Central

Costa, D L; Dreher, K L

1997-01-01

Many epidemiologic reports associate ambient levels of particulate matter (PM) with human mortality and morbidity, particularly in people with preexisting cardiopulmonary disease (e.g., chronic obstructive pulmonary disease, infection, asthma). Because much ambient PM is derived from combustion sources, we tested the hypothesis that the health effects of PM arise from anthropogenic PM that contains bioavailable transition metals. The PM samples studied derived from three emission sources (two oil and one coal fly ash) and four ambient airsheds (St. Louis, MO; Washington; Dusseldorf, Germany; and Ottawa, Canada). PM was administered to rats by intratracheal instillation in equimass or equimetal doses to address directly the influence of PM mass versus metal content on acute lung injury and inflammation. Our results indicated that the lung dose of bioavailable transition metal, not instilled PM mass, was the primary determinant of the acute inflammatory response for both the combustion source and ambient PM samples. Residual oil fly ash, a combustion PM rich in bioavailable metal, was evaluated in a rat model of cardiopulmonary disease (pulmonary vasculitis/hypertension) to ascertain whether the disease state augmented sensitivity to that PM. Significant mortality and enhanced airway responsiveness were observed. Analysis of the lavaged lung fluids suggested that the milieu of the inflamed lung amplified metal-mediated oxidant chemistry to jeopardize the compromised cardiopulmonary system. We propose that soluble metals from PM mediate the array of PM-associated injuries to the cardiopulmonary system of the healthy and at-risk compromised host. PMID:9400700

Potential of acetylacetone as a mediator for Trametes versicolor laccase in enzymatic transformation of organic pollutants.

PubMed

Yang, Hua; Sun, Hongfei; Zhang, Shujuan; Wu, Bingdang; Pan, Bingcai

2015-07-01

Low-cost and environmentally friendly mediators could facilitate the application of laccase (EC 1.10.3.2) in variant biotechnological processes. Acetylacetone (AA) represents an inexpensive and low toxic small molecular diketone that has been proven as an effective mediator for laccase in free radical polymerization. However, the potential of AA as a mediator for laccase in pollutant detoxification and/or degradation is still unknown. In this work, the roles of AA in laccase-induced polymerization and transformation were investigated. AA was demonstrated to be a highly efficient mediator in the laccase-induced grafting copolymerization of acrylamide and chitosan. The efficacy of AA in the laccase-induced decoloration of malachite green (MG) was compared with that of the widely used 1-hydroxybenzotriazole (HBT). The laccase-AA system had the highest turnover number (TON, 39.1 μmol/U), followed by the laccase-only system (28.5 μmol/U), while the TON of the laccase-HBT system was the lowest (14.9 μmol/U). The pseudo-first-order transformation rate constant (k 1) of MG in the laccase-AA system was up to 0.283 h(-1) under the given conditions, while the k 1 of AA caused by laccase was only 0.008 h(-1). In the five-cycle run, the concentration of AA remained stable. The larger TON of the laccase-AA system and the stability of AA in the cycling runs demonstrate that AA was more recyclable than HBT in the LMS, leading to a prolonged serving life of laccase. These results suggest that AA might be a potential redox mediator for laccase.

Transformation and bioavailability of metal oxide nanoparticles in aquatic and terrestrial environments. A review.

PubMed

Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

2017-11-01

Metal oxide nanoparticles (MeO-NPs) are among the most consumed NPs and also have wide applications in various areas which increased their release into the environmental system. Aquatic (water and sediments) and terrestrial compartments are predicted to be the destination of the released MeO-NPs. In these compartments, the particles are subjected to various dynamic processes such as physical, chemical and biological processes, and undergo transformations which drive them away from their pristine state. These transformation pathways can have strong implications for the fate, transport, persistence, bioavailability and toxic-effects of the NPs. In this critical review, we provide the state-of-the-knowledge on the transformation processes and bioavailability of MeO-NPs in the environment, which is the topic of interest to researchers. We also recommend future research directions in the area which will support future risk assessments by enhancing our knowledge of the transformation and bioavailability of MeO-NPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Six1 overexpression at early stages of HPV16-mediated transformation of human keratinocytes promotes differentiation resistance and EMT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Hanwen; Pirisi, Lucia; Creek, Kim E., E-mail: creekk@sccp.sc.edu

Previous studies in our laboratory discovered that SIX1 mRNA expression increased during in vitro progression of HPV16-immortalized human keratinocytes (HKc/HPV16) toward a differentiation-resistant (HKc/DR) phenotype. In this study, we explored the role of Six1 at early stages of HPV16-mediated transformation by overexpressing Six1 in HKc/HPV16. We found that Six1 overexpression in HKc/HPV16 increased cell proliferation and promoted cell migration and invasion by inducing epithelial–mesenchymal transition (EMT). Moreover, the overexpression of Six1 in HKc/HPV16 resulted in resistance to serum and calcium-induced differentiation, which is the hallmark of the HKc/DR phenotype. Activation of MAPK in HKc/HPV16 overexpressing Six1 is linked to resistancemore » to calcium-induced differentiation. In conclusion, this study determined that Six1 overexpression resulted in differentiation resistance and promoted EMT at early stages of HPV16-mediated transformation of human keratinocytes. - Highlights: • Six1 expression increases during HPV16-mediated transformation. • Six1 overexpression causes differentiation resistance in HPV16-immortalized cells. • Six1 overexpression in HPV16-immortalized keratinocytes activates MAPK. • Activation of MAPK promotes EMT and differentiation resistance. • Six1 overexpression reduces Smad-dependent TGF-β signaling.« less

Assessing the impact of As-Cd-Pb metal mixture on cell transformation by two-stage Balb/c 3T3 cell assay.

PubMed

Rodríguez-Sastre, M A; Rojas, E; Valverde, M

2014-07-01

Human beings are exposed to metals as a consequence of various industrial activities, including glass production, agrochemical production, metallurgy and battery manufacture. New data about the possible mechanisms involved in the carcinogenic activity of these metals are constantly being reported. Exposure to complex mixtures of metals is more likely to occur than exposure to a single metal alone. Among these elements, arsenic, cadmium and lead are ubiquitous air and water pollutants that continue to threaten the quality of public health around the world. The aim of the present study was to evaluate the capability of a mixture of 2 µM NaAsO2, 2 µM CdCl2 and 5 µM Pb(C2H3O2)2·3H2O at relevant epidemiological concentrations to induce cell transformation processes. Transforming potential was determined by a murine two-stage Balb/c 3T3 cell assay. Cell viability, reactive oxygen species (ROS), DNA damage, cell cycle analysis, senescence, generation time and metallothionein expression were also evaluated. The results showed that the metal mixture induced morphological cell transformation only when acting as initiator stimuli of the process. A decrease in cell viability was observed at the promotion stage, a time during which ROS increase, especially when a metal mixture was applied as a promoter stimulant. Changes in DNA damage were not observed throughout the assay; however, we observed G1 cell cycle arrest. The metal mixture, acting as a promoter, is capable of inducing senescence, but metals employed as initiators with 12-O-tetradecanoylphorbol-13-acetate as a promoter are capable of causing avoidance of senescence and triggering the transformation potential of the cells. © The Author 2014. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Guest-Induced Two-Way Structural Transformation in a Layered Metal-Organic Framework Thin Film.

PubMed

Haraguchi, Tomoyuki; Otsubo, Kazuya; Sakata, Osami; Fujiwara, Akihiko; Kitagawa, Hiroshi

2016-12-28

Fabrication of thin films made of metal-organic frameworks (MOFs) has been intensively pursued for practical applications that use the structural response of MOFs. However, to date, only physisorption-induced structural response has been studied in these films. Chemisorption can be expected to provide a remarkable structural response because of the formation of bonds between guest molecules and reactive metal sites in host MOFs. Here, we report that chemisorption-induced two-way structural transformation in a nanometer-sized MOF thin film. We prepared a two-dimensional layered-type MOF Fe[Pt(CN) 4 ] thin film using a step-by-step approach. Although the as-synthesized film showed poor crystallinity, the dehydrated form of this thin film had a highly oriented crystalline nature (Film-D) as confirmed by synchrotron X-ray diffraction (XRD). Surprisingly, under water and pyridine vapors, Film-D showed chemisorption-induced dynamic structural transformations to Fe(L) 2 [Pt(CN) 4 ] thin films [L = H 2 O (Film-H), pyridine (Film-P)], where water and pyridine coordinated to the open Fe 2+ site. Dynamic structural transformations were also confirmed by in situ XRD, sorption measurement, and infrared reflection absorption spectroscopy. This is the first report of chemisorption-induced dynamic structural response in a MOF thin film, and it provides useful insights, which would lead to future practical applications of MOFs utilizing chemisorption-induced structural responses.

Investigating different mechanisms for biogenic selenite transformations: Geobacter sulfurreducens, Shewanella oneidensis and Veillonella atypica

USGS Publications Warehouse

Pearce, C.I.; Pattrick, R.A.D.; Law, N.; Charnock, J.M.; Coker, V.S.; Fellowes, J.W.; Oremland, R.S.; Lloyd, J.R.

2009-01-01

The metal-reducing bacteria Geobacter sulfurreducens, Shewanella oneidensis and Veillonella atypica, use different mechanisms to transform toxic, bioavailable sodium selenite to less toxic, non-mobile elemental selenium and then to selenide in anaerobic environments, offering the potential for in situ and ex situ bioremediation of contaminated soils, sediments, industrial effluents, and agricultural drainage waters. The products of these reductive transformations depend on both the organism involved and the reduction conditions employed, in terms of electron donor and exogenous extracellular redox mediator. The intermediary phase involves the precipitation of elemental selenium nanospheres and the potential role of proteins in the formation of these structures is discussed. The bionanomineral phases produced during these transformations, including both elemental selenium nanospheres and metal selenide nanoparticles, have catalytic, semiconducting and light-emitting properties, which may have unique applications in the realm of nanophotonics. This research offers the potential to combine remediation of contaminants with the development of environmentally friendly manufacturing pathways for novel bionanominerals. ?? 2009 Taylor & Francis.

High Pressure Phase Transformations in Heavy Rare Earth Metals and Connections to Actinide Crystal Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vohra, Yogesh K.; Sangala, Bagvanth Reddy; Stemshorn, Andrew K.

2008-07-01

High-pressure studies have been performed on heavy rare earth metals Terbium (Tb) to 155 GPa and Holmium (Ho) to 134 GPa in a diamond anvil cell at room temperature. The following crystal structure sequence was observed in both metals hcp {yields} Sm-type {yields} dhcp {yields} distorted fcc (hR-24) {yields} monoclinic (C2/m) with increasing pressure. The last transformation to a low symmetry monoclinic phase is accompanied by a volume collapse of 5 % for Tb at 51 GPa and a volume collapse of 3 % for Ho at 103 GPa. This volume collapse under high pressure is reminiscent of f-shell delocalizationmore » in light rare earth metal Cerium (Ce), Praseodymium (Pr), and heavy actinide metals Americium (Am) and Curium (Cm). The orthorhombic Pnma phase that has been reported in Am and Cm after f-shell delocalization is not observed in heavy rare earth metals under high pressures. (authors)« less

Transformation of heavy metal fractionation under changing environments: a case study of a drainage system in an e-waste dismantling community.

PubMed

Damrongsiri, Seelawut

2018-04-01

The change in environmental conditions during the transportation of contaminated soil and sediment was expected to affect the transformation of heavy metal fractionation. This study disclosed the serious contamination of copper (Cu), lead (Pb), and zinc (Zn) in the sewer sediment of an e-waste dismantling community in Thailand which may be caused by flushed contaminated soil and e-waste fragments. Two environmental conditions were simulated to observe the transformation of heavy metal fractionation. The anoxic sewer condition was induced using high substrate and sulfate in a closed container. The aeration of anoxic contaminated sediment was applied to simulate the transformation to an oxidative environment. The BCR sequential extraction was applied for heavy metal fractionation in this study. The study results exhibited that when heavy metal contaminated soil was transferred into this induced anoxic condition, fractionation was redistributed based on the chemical change of system that tends to be associated into F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (acid soluble/exchangeable fraction). Cu exhibited the outstanding capability association to F3. The iron sulfide was not observed as usual due to its lower capability than Cu, Pb, and Zn. When contaminated sediment was transported to a more oxidative environment, the heavy metals fractionation would be redistributed again among those new environment media. It is noteworthy that F3 of Cu was stable even in oxic conditions. F2 of Fe was not developed by this oxic condition, possibly because its dehydration process was limited. The redistribution under an oxic environment became F1 > F2 > F3 indicating their more available form. This transformation was imperative and should be taken into account in heavy metal contaminated site management and control.

Methods for genetic transformation of filamentous fungi.

PubMed

Li, Dandan; Tang, Yu; Lin, Jun; Cai, Weiwen

2017-10-03

Filamentous fungi have been of great interest because of their excellent ability as cell factories to manufacture useful products for human beings. The development of genetic transformation techniques is a precondition that enables scientists to target and modify genes efficiently and may reveal the function of target genes. The method to deliver foreign nucleic acid into cells is the sticking point for fungal genome modification. Up to date, there are some general methods of genetic transformation for fungi, including protoplast-mediated transformation, Agrobacterium-mediated transformation, electroporation, biolistic method and shock-wave-mediated transformation. This article reviews basic protocols and principles of these transformation methods, as well as their advantages and disadvantages.

Second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass.

PubMed

Cao, Q P; Li, J F; Zhang, P N; Horsewell, A; Jiang, J Z; Zhou, Y H

2007-06-20

The second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass was investigated by differential scanning calorimetry and x-ray diffractometry. The difference of the Gibbs free energies between the amorphous phase and the crystalline products during the transformation is estimated to be about 2.46 kJ mol(-1) at 753 K, much smaller than the 61 kJ mol(-1) obtained assuming that it is a polymorphic transformation. It was revealed that the phase transformation occurs through a eutectic crystallization of Cu(51)Zr(14) and Cu(2)TiZr, having an effective activation energy of the order of 400 kJ mol(-1). The average Avrami exponent n is about 2.0, indicating that the crystallization is diffusion controlled.

Co-detoxification of transformer oil-contained PCBs and heavy metals in medical waste incinerator fly ash under sub- and supercritical water.

PubMed

Wang, Chunfeng; Zhu, Nengmin; Wang, Yanmin; Zhang, Fushen

2012-01-17

The simultaneous detoxification processes of transformer oil-contained PCBs and heavy metals in medical waste incinerator (MWI) fly ash were developed under sub- and supercritical water. The addition of MWI fly ash to transformer oil-contained PCBs was found to increase the destruction efficiency of PCBs, at the same time, it facilitated reducing the leaching concentration of toxic metals from residues (obtained after reaction) for harmless disposal. In this study, we elucidated primarily the catalysis possibility of heavy metals in raw MWI fly ash for PCBs degradation by adopting the sequential extraction procedure. For both MWI fly ashes, more than 90% destruction efficiency of PCBs was achieved at ≥375 °C for 30 min, and trichlorobenzene (TCB) existing in the transformer oil was also completely decomposed. The correlation of catalytic performance to PCBs degradation was discussed based on structural characteristics and dechlorinated products. Likewise, such process rendered residues innocuous through supercritical water treatment for reuse or disposal in landfill.

EFFECT OF HUMIC CONSTITUENTS ON THE TRANSFORMATION OF CHLORINATED PHENOLS AND ANILINES IN THE PRESENCE OF OXIDOREDUCTIVE ENZYMES OR BIRNESSITE. (R823847)

EPA Science Inventory

Chlorinated phenols and anilines are transformed and detoxified in soil
through oxidative coupling reactions mediated by enzymes or metal oxides. The
reactions may be influenced by humic constituents, such as syringaldehyde or
catechol, that originate from lignin d...

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

PubMed

Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies of Metal-Metal Bonded Compounds in Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, John F.

The overall goals of this research are (1) to define the fundamental coordination chemistry underlying successful catalytic transformations promoted by metal-metal bonded compounds, and (2) to explore new chemical transformations that occur at metal-metal bonded sites that could lead to the discovery of new catalytic processes. Transformations of interest include metal-promoted reactions of carbene, nitrene, or nitrido species to yield products with new C–C and C–N bonds, respectively. The most promising suite of transition metal catalysts for these transformations is the set of metal-metal bonded coordination compounds of Ru and Rh of the general formula M 2(ligand) 4, where Mmore » = Ru or Rh and ligand = a monoanionic, bridging ligand such as acetate. Development of new catalysts and improvement of catalytic conditions have been stymied by a general lack of knowledge about the nature of highly reactive intermediates in these reactions, the knowledge that is to be supplied by this work. Our three specific objectives for this year have been (A) to trap, isolate, and characterize new reactive intermediates of general relevance to catalysis, (B) to explore the electronic structure and reactivity of these unusual species, and how these two properties are interrelated, and (C) to use our obtained mechanistic knowledge to design new catalysts with a focus on Earth-abundant first-row transition metal compounds.« less

Ionothermal synthesis and structural transformation targeted by ion exchange in metal-1,3,5-benzenetricarboxylate compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Qing-Qing; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002; Liu, Bing

Ionothermal reactions of 1,3,5-benzenetricarboxylate acid (H{sub 3}BTC) and Ni(NO{sub 3}){sub 2}, Co(NO{sub 3}){sub 2} and Cu(NO{sub 3}){sub 2} gave two discrete 32-membered ring-like allomers, [M{sub 2}(HBTC){sub 2}(NH{sub 2}CONH{sub 2}){sub 2}(H{sub 2}O){sub 4}]·3H{sub 2}O (M=Ni(1), Co(2)) and one layered [Cu{sub 2}(BTC)Cl(H{sub 2}O){sub 4}] (3). The weak interactions in 1 can be deconstructed to some degree in ion exchange by exploring the factors of divalent and trivalent metal species, metal concentration and soaking time, which are demonstrated by PXRD and N{sub 2} absorption. Cu{sup 2+} has the highest N{sub 2} adsorbance when soaking with 1, and 1 can keep structure stable whenmore » Cu{sup 2+} below 0.16 mol L{sup −1} and the soaking time within 24d. As Cu{sup 2+} beyond 0.16 mol L{sup −1} and the soaking time beyond 24d, the structure of compound 1 starts to transform with the crystal morphology from clear pale green to opaque blue. Ionothermal reactions of compound 1 with different Cu{sup 2+} amounts obtained Ni{sup 2+}-Cu{sup 2+} hetero complexes, whose PXRD patterns are similar to that of 3 and EDS indicates Cu{sup 2+}% increases with Cu{sup 2+} additions and close to 100% as Cu{sup 2+} being 1.6 mmol. It suggests that 3 is a controlled product and Cu{sup 2+} can transform discrete compound 1 into 2D compound 3. - Graphical abstract: Three compounds were synthesized through ionothermal reactions. The weak interactions in compound 1 can be deconstructed by ion exchange and discrete compound 1 can be transformed into layered compound 3. - Highlights: • Two discrete ring-like and one layered compounds were ionothermally synthesized. • Metal species, metal concentration and soaking time deconstruct the H-bondings in 1. • 1 can be transformed to 3 through ionothermal reaction, otherwise forbidden.« less

Fungal inoculation and elevated CO2 mediate growth of Lolium mutiforum and Phytolacca americana, metal uptake, and metal bioavailability in metal-contaminated soil: evidence from DGT measurement.

PubMed

Song, Ningning; Wang, Fangli; Zhang, Changbo; Tang, Shirong; Guo, Junkang; Ju, Xuehai; Smith, Donald L

2013-01-01

Fungal inoculation and elevated CO2 may mediate plant growth and uptake of heavy metals, but little evidence from Diffusive Gradients in Thin-films (DGT) measurement has been obtained to characterize the process. Lolium mutiforum and Phytolacca americana were grown at ambient and elevated CO2 on naturally Cd and Pb contaminated soils inoculated with and without Trichoderma asperellum strain C3 or Penicillium chrysogenum strain D4, to investigate plant growth, metal uptake, and metal bioavailability responses. Fungal inoculation increased plant biomass and shoot/root Cd and Pb concentrations. Elevated CO2 significantly increased plants biomass, but decreased Cd and Pb concentrations in shoot/root to various extents, leading to a metal dilution phenomenon. Total Cd and Pb uptake by plants, and DGT-measured Cd and Pb concentrations in rhizosphere soils, were higher in all fungal inoculation and elevated CO2 treatments than control treatments, with the combined treatments having more influence than either treatment alone. Metal dilution phenomenon occurred because the increase in DGT-measured bioavailable metal pools in plant rhizosphere due to elevated CO2 was unable to match the increase in requirement for plant uptake of metals due to plant biomass increase.

A new high-frequency Agrobacterium-mediated transformation technique for Sesamum indicum L. using de-embryonated cotyledon as explant.

PubMed

Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha

2014-09-01

In spite of the economic importance of sesame (Sesamum indicum L.) and the recent availability of its genome sequence, a high-frequency transformation protocol is still not available. The only two existing Agrobacterium-mediated transformation protocols that are available have poor transformation efficiencies of less than 2%. In the present study, we report a high-frequency, simple, and reproducible transformation protocol for sesame. Transformation was done using de-embryonated cotyledons via somatic embryogenic stages. All the critical parameters of transformation, like incubation period of explants in pre-regeneration medium prior to infection by Agrobacterium tumefaciens, cocultivation period, concentrations of acetosyringone in cocultivation medium, kanamycin concentration, and concentration of plant hormones, including 6-benzylaminopurine, have been optimized. This protocol is superior to the two existing protocols in its high regeneration and transformation efficiencies. The transformed sesame lines have been tested by PCR, RT-PCR for neomycin phosphotransferase II gene expression, and β-glucuronidase (GUS) assay. The regeneration frequency and transformation efficiency are 57.33 and 42.66%, respectively. T0 and T1 generation transgenic plants were analyzed, and several T1 plants homozygous for the transgenes were obtained.

Transforming growth factor-beta1 mediates cellular response to DNA damage in situ

NASA Technical Reports Server (NTRS)

Ewan, Kenneth B.; Henshall-Powell, Rhonda L.; Ravani, Shraddha A.; Pajares, Maria Jose; Arteaga, Carlos; Warters, Ray; Akhurst, Rosemary J.; Barcellos-Hoff, Mary Helen

2002-01-01

Transforming growth factor (TGF)-beta1 is rapidly activated after ionizing radiation, but its specific role in cellular responses to DNA damage is not known. Here we use Tgfbeta1 knockout mice to show that radiation-induced apoptotic response is TGF-beta1 dependent in the mammary epithelium, and that both apoptosis and inhibition of proliferation in response to DNA damage decrease as a function of TGF-beta1 gene dose in embryonic epithelial tissues. Because apoptosis in these tissues has been shown previously to be p53 dependent, we then examined p53 protein activation. TGF-beta1 depletion, by either gene knockout or by using TGF-beta neutralizing antibodies, resulted in decreased p53 Ser-18 phosphorylation in irradiated mammary gland. These data indicate that TGF-beta1 is essential for rapid p53-mediated cellular responses that mediate cell fate decisions in situ.

Knowledge management as a mediator for the efficacy of transformational leadership and quality management initiatives in U.S. health care.

PubMed

Gowen, Charles R; Henagan, Stephanie C; McFadden, Kathleen L

2009-01-01

The health care industry has become one of the largest sectors of the U.S. economy and provides the greatest job growth of any industry. With such growth, effective leadership, knowledge management, and quality programs can ameliorate patient safety outcomes and improve organizational performance. This exploratory study examines the efficacy of transformational leadership, knowledge management, and quality initiatives, each of which has been proven effective in health care organizations. The literature has neglected the relationships among these three types of programs, although they are increasingly implemented simultaneously now. This research tests the degree to which knowledge management could act as a mediator of the effects transformational leadership and quality management have on organizational performance for hospitals. Our survey of U.S. hospitals utilizes validated scales from the literature. By calling and e-mailing quality and other department directors, the data set includes responses from all 50 states in our sample of 370 U.S. hospitals. Statistical tests confirmed acceptable regional distribution, interrater reliability, and control variable characteristics for our sample. Structural equation modeling is used to test the research hypotheses. These preliminary results reveal that transformational leadership and quality management improve knowledge management. In addition, transformational leadership is fully mediated by knowledge responsiveness and quality management is partially mediated by knowledge responsiveness for their effects on organizational performance. The unique contribution of this study includes the suggestion that greater transformational leadership skills are important for health care executives to motivate successful knowledge management initiatives. Secondly, continuous improvements in quality management programs have significant positive impacts on knowledge management and organizational outcomes in hospitals. Finally, successful

Detection of Oil Palm Root Penetration by Agrobacterium-Mediated Transformed Ganoderma boninense, Expressing Green Fluorescent Protein.

PubMed

Govender, Nisha; Wong, Mui-Yun

2017-04-01

A highly efficient and reproducible Agrobacterium-mediated transformation protocol for Ganoderma boninense was developed to facilitate observation of the early stage infection of basal stem rot (BSR). The method was proven amenable to different explants (basidiospore, protoplast, and mycelium) of G. boninense. The transformation efficiency was highest (62%) under a treatment combination of protoplast explant and Agrobacterium strain LBA4404, with successful expression of an hyg marker gene and gus-gfp fusion gene under the control of heterologous p416 glyceraldehyde 3-phosphate dehydrogenase promoter. Optimal transformation conditions included a 1:100 Agrobacterium/explant ratio, induction of Agrobacterium virulence genes in the presence of 250 μm acetosyringone, co-cultivation at 22°C for 2 days on nitrocellulose membrane overlaid on an induction medium, and regeneration of transformants on potato glucose agar prepared with 0.6 M sucrose and 20 mM phosphate buffer. Evaluated transformants were able to infect root tissues of oil palm plantlets with needle-like microhyphae during the penetration event. The availability of this model pathogen system for BSR may lead to a better understanding of the pathogenicity factors associated with G. boninense penetration into oil palm roots.

Optimization of factors influencing microinjection method for Agrobacterium tumefaciens-mediated transformation of tomato.

PubMed

Vinoth, S; Gurusaravanan, P; Jayabalan, N

2013-02-01

A simple and efficient protocol for Agrobacterium-mediated genetic transformation of tomato was developed using combination of non-tissue culture and micropropagation systems. Initially, ESAM region of 1-day-old germinated tomato seeds were microinjected for one to five times with Agrobacterium inoculums (OD(600) = 0.2-1.0). The germinated seeds were cocultivated in the MS medium fortified with (0-200 mM) acetosyringone and minimal concentrations of (0-20 mg L(-1)) kanamycin, and the antibiotic concentration was doubled during the second round of selection. Bacterial concentration of OD(600) = 0.6 served as an optimal concentration for infection and the transformation efficiency was significantly higher of about 46.28 %. In another set of experiment, an improved and stable regeneration system was adapted for the explants from the selection medium. Four-day-old double cotyledonary nodal explants were excised from the microinjected seedlings and cultured onto the MS medium supplemented with 1.5 mg L(-1) thidiazuron, 1.5 mg L(-1) indole-3-butyric acid, 30 mg L(-1) kanamycin, and 0-1.5 mg L(-1) adenine sulphate. Maximum of 9 out of 13 micropropagated shoots were shown positive to GUS assay. By this technique, the transformation efficiency was increased from 46.28 to 65.90 %. Thus, this paper reports the successful protocol for the mass production of transformants using microinjection and micropropagation techniques.

In situ atomic-scale imaging of the metal/oxide interfacial transformation

DOE PAGES

Zou, Lianfeng; Li, Jonathan; Zakharov, Dmitri; ...

2017-08-21

Directly probing structure dynamics at metal/oxide interfaces has been a major challenge due to their buried nature.Using environmental transmission electron microscopy,here we report observations of the in-place formation of Cu 2O/Cu interfaces via the oxidation of Cu, and subsequently probe the atomic mechanisms by which interfacial transformation and grain rotation occur at the interfaces during reduction in an H 2 gas environment. The Cu 2O→Cu transformation is observed to occur initially along the Cu 2O/Cu interface in a layer-by-layer manner.The accumulation of oxygen vacancies at the Cu 2O/Cu interface drives the collapse of the Cu 2O lattice near the interfacemore » region, which results in a tilted Cu 2O/Cu interface with concomitant Cu 2O island rotation. Lastly, these results provide unprecedented microscopic detail regarding the redox reactions of supported oxides,which differs fundamentally from the reduction of bulk or isolated oxides that requires the formation of new interfaces between the parent oxide and the reduced phase.« less

Assessment of factors affecting Agrobacterium-mediated genetic transformation of the unicellular green alga, Chlorella vulgaris.

PubMed

Cha, Thye San; Yee, Willy; Aziz, Ahmad

2012-04-01

The successful establishment of an Agrobacterium-mediated transformation method and optimisation of six critical parameters known to influence the efficacy of Agrobacterium T-DNA transfer in the unicellular microalga Chlorella vulgaris (UMT-M1) are reported. Agrobacterium tumefaciens strain LBA4404 harbouring the binary vector pCAMBIA1304 containing the gfp:gusA fusion reporter and a hygromycin phosphotransferase (hpt) selectable marker driven by the CaMV35S promoter were used for transformation. Transformation frequency was assessed by monitoring transient β-glucuronidase (GUS) expression 2 days post-infection. It was found that co-cultivation temperature at 24°C, co-cultivation medium at pH 5.5, 3 days of co-cultivation, 150 μM acetosyringone, Agrobacterium density of 1.0 units (OD(600)) and 2 days of pre-culture were optimum variables which produced the highest number of GUS-positive cells (8.8-20.1%) when each of these parameters was optimised individually. Transformation conducted with the combination of all optimal parameters above produced 25.0% of GUS-positive cells, which was almost a threefold increase from 8.9% obtained from un-optimised parameters. Evidence of transformation was further confirmed in 30% of 30 randomly-selected hygromycin B (20 mg L(-1)) resistant colonies by polymerase chain reaction (PCR) using gfp:gusA and hpt-specific primers. The developed transformation method is expected to facilitate the genetic improvement of this commercially-important microalga.

Determination of Trace Available Heavy Metals in Soil Using Laser-Induced Breakdown Spectroscopy Assisted with Phase Transformation Method.

PubMed

Yi, Rongxing; Yang, Xinyan; Zhou, Ran; Li, Jiaming; Yu, Huiwu; Hao, Zhongqi; Guo, Lianbo; Li, Xiangyou; Lu, Yongfeng; Zeng, Xiaoyan

2018-05-18

To detect available heavy metals in soil using laser-induced breakdown spectroscopy (LIBS) and improve its poor detection sensitivity, a simple and low cost sample pretreatment method named solid-liquid-solid transformation was proposed. By this method, available heavy metals were extracted from soil through ultrasonic vibration and centrifuging and then deposited on a glass slide. Utilization of this solid-liquid-solid transformation method, available Cd and Pb elements in soil were detected successfully. The results show that the regression coefficients of calibration curves for soil analyses reach to more than 0.98. The limits of detection could reach to 0.067 and 0.94 ppm for available Cd and Pb elements in soil under optimized conditions, respectively, which are much better than those obtained by conventional LIBS.

Cadmium-induced malignant transformation of rat liver cells: Potential key role and regulatory mechanism of altered apolipoprotein E expression in enhanced invasiveness.

PubMed

Suzuki, Masayo; Takeda, Shuso; Teraoka-Nishitani, Noriko; Yamagata, Akane; Tanaka, Takahiro; Sasaki, Marika; Yasuda, Natsuki; Oda, Makiko; Okano, Tatsuji; Yamahira, Kazuhiro; Nakamura, Yuta; Kobayashi, Takanobu; Kino, Katsuhito; Miyazawa, Hiroshi; Waalkes, Michael P; Takiguchi, Masufumi

2017-05-01

Cadmium is a transition metal that is classified as human carcinogen by the International Agency for Research on Cancer (IARC) with multiple target sites. Many studies using various model systems provide evidence of cadmium-induced malignancy formation in vivo or malignant cell transformation in vitro. Nonetheless, further studies are needed to completely understand the mechanisms of cadmium carcinogenicity. Our prior studies have utilized a rat liver epithelial cell line (TRL 1215) as a model for cadmium-induced malignant transformation. In the present study, we focused on the molecular mechanisms of this malignant transformation, especially with regard to hyper-invasiveness stimulated by cadmium transformation. By performing a series of biochemical analyses on cadmium transformed cells, it was determined that cadmium had significantly down-regulated the expression of apolipoprotein E (ApoE). ApoE was recently established as a suppressor of cell invasion. A key factor in the suppression of ApoE by cadmium appeared to be that the metal evoked a 5-aza-2'-deoxycytidine-sensitive hypermethylation of the regulatory region of ApoE, coupled with interference of the action of liver X receptor α (LXRα), a transcriptional regulator for ApoE. Furthermore, the expression of LXRα itself was suppressed by cadmium-mediated epigenetic modification. Re-expression of ApoE clearly abrogated the cell invasion stimulated by cadmium-induced malignant transformation. Together, the current results suggest that the cadmium-mediated enhanced cell invasion is linked to down-regulation of ApoE during malignant transformation these liver cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Agrobacterium tumefaciens-mediated transformation of Lasiodiplodia theobromae, the causal agent of gummosis in cashew nut plants.

PubMed

Muniz, C R; da Silva, G F; Souza, M T; Freire, F C O; Kema, G H J; Guedes, M I F

2014-02-21

Lasiodiplodia theobromae is a major pathogen of many different crop cultures, including cashew nut plants. This paper describes an efficient Agrobacterium tumefaciens-mediated transformation (ATMT) system for the successful delivery of T-DNA, transferring the genes of green fluorescent protein (gfp) and hygromycin B phosphotransferase (hph) to L. theobromae. When the fungal pycnidiospores were co-cultured with A. tumefaciens harboring the binary vector with hph-gfp gene, hygromycin-resistant fungus only developed with acetosyringone supplementation. The cashew plants inoculated with the fungus expressing GFP revealed characteristic pathogen colonization by epifluorescence microscopy. Intense and bright green hyphae were observed for transformants in all extensions of mycelium cultures. The penetration of parenchyma cells near to the inoculation site, beneath the epicuticle surface, was observed prior to 25 dpi. Penetration was followed by the development of hyphae within invaded host cells. These findings provide a rapid and reproducible ATMT method for L. theobromae transformation.

Effects of biochar on nitrogen transformation and heavy metals in sludge composting.

PubMed

Liu, Wei; Huo, Rong; Xu, Junxiang; Liang, Shuxuan; Li, Jijin; Zhao, Tongke; Wang, Shutao

2017-07-01

Composting is regarded as an effective treatment to suppress pathogenic organisms and stabilize the organic material in sewage sludge. This study investigated the use of biochar as an amendment to improve the composting effectiveness and reduce the bioavailability of heavy metals and loss of nitrogen during composting. Biochar of 0%, 1%, 3%, 5% and 7% were added into a mixture of sludge and straw, respectively. The use of biochar, even in small amounts, altered the composting process and the properties of the end products. Biochar addition resulted in a higher pile temperature (66°C) and could reduce nitrogen loss by transforming ammonium into nitrite. In the 5% biochar group, the final product from sludge composting, ammonia nitrogen, decreased by 22.4% compared to the control, and nitrate nitrogen increased by 310.6%. Considering temperature and N transformation, the treatment with 5% biochar is suggested for sludge composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.

PubMed

Ishiwata, Takumi; Furukawa, Yuki; Sugikawa, Kouta; Kokado, Kenta; Sada, Kazuki

2013-04-10

Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.

Shape-transformable liquid metal nanoparticles in aqueous solution† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00057j Click here for additional data file.

PubMed Central

Lin, Yiliang; Liu, Yang

2017-01-01

Stable suspensions of eutectic gallium indium (EGaIn) liquid metal nanoparticles form by probe-sonicating the metal in an aqueous solution. Positively-charged molecular or macromolecular surfactants in the solution, such as cetrimonium bromide or lysozyme, respectively, stabilize the suspension by interacting with the negative charges of the surface oxide that forms on the metal. The liquid metal breaks up into nanospheres via sonication, yet can transform into rods of gallium oxide monohydroxide (GaOOH) via moderate heating in solution either during or after sonication. Whereas heating typically drives phase transitions from solid to liquid (via melting), here heating drives the transformation of particles from liquid to solid via oxidation. Interestingly, indium nanoparticles form during the process of shape transformation due to the selective removal of gallium. This dealloying provides a mechanism to create indium nanoparticles at temperatures well below the melting point of indium. To demonstrate the versatility, we show that it is possible to shape transform and dealloy other alloys of gallium including ternary liquid metal alloys. Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS) mapping, and X-ray diffraction (XRD) confirm the dealloying and transformation mechanism. PMID:28580116

Super electron donor-mediated reductive transformation of nitrobenzenes: a novel strategy to synthesize azobenzenes and phenazines.

PubMed

Nozawa-Kumada, Kanako; Abe, Erina; Ito, Shungo; Shigeno, Masanori; Kondo, Yoshinori

2018-05-02

The transformation of nitrobenzenes into azobenzenes by pyridine-derived super electron donor 2 is described. This method provides an efficient synthesis of azobenzenes because of not requiring the use of expensive transition-metals, toxic or flammable reagents, or harsh conditions. Moreover, when using 2-fluoronitrobenzenes as substrates, phenazines were found to be obtained. The process affords a novel synthesis of phenazines.

[Effects of strong reductive process on transformation of heavy metals in protected vegetable soil].

PubMed

Sun, Yan Chen; Zeng, Xiang Feng; Yang, Li Qiong; Shi, Ya Nan; Chen, Xi Juan; Zhuang, Jie

2017-11-01

The application of sewage and manure in protected vegetable cultivation can induce the occurrence of heavy metals contamination. The present research studied the transformation of heavy metals (Cd, Cu, Pb and Zn) by incubating contaminated protected soil with maize straw and then leaching. The results showed that soil pH was significantly decreased, being more evident in maize straw treatment; soil Eh dropped quickly below -280 mV. Maize straw treatment promoted the activation of Cd, Cu, Pb and Zn from soil, and the total percent of oxidizable fraction and residual fraction of Cd, Cu, Pb and Zn declined at 9 th day; the amount of Cd, Cu, Pb and Zn in soil reduced 18.1%, 19.0%, 16.1% and 15.7% at 15 th day, respectively. Compared to control, maize straw treatment could increase the concentrations of dissolved Cd and Zn, but Cu decreased. The concentration of colloidal-bound Cd and Pb increased, Cu decreased and no significant change occurred in Zn in maize straw treatment. Strong reductive approach could activate heavy metals in protected vegetable soil, increase the risk of heavy metals accumulation in vegetables, and possibly cause water pollution accompanied with soil water mobilization.

Transformation of soybean Gy3 gene into Artemisaarenaria mediated by corona discharge

NASA Astrophysics Data System (ADS)

Chao, Lu-meng; Na, Ri; Xue, Dan; Xu, Yongze; Liu, Teng

2013-03-01

In order to improve the protein content of desert plant, a method of genetic transformation mediated by corona discharge was established. Artemisia seeds were processed in corona electric field for 120 min at 12 kV, and then soaked in 0.1 SSC media that contained Soybean Gy3 gene DNA to incubate for 12 h at 26 °C. Finally the seeds were inoculated on the differentiation medium. Polymerase Chain Reaction (PCR) and Reverse Transcription Polymerase Chain Reaction (RT-PCR) detection showed that the Soybean Gy3 gene had been successfully introduced into genomic DNA of the regenerated plants of Artemisaarenaria. The study provided a new way for corona discharge in plant genetic modification.

Increased Agrobacterium-mediated transformation and rooting efficiencies in canola (Brassica napus L.) from hypocotyl segment explants

NASA Technical Reports Server (NTRS)

Cardoza, V.; Stewart, C. N.

2003-01-01

An efficient protocol for the production of transgenic Brassica napus cv. Westar plants was developed by optimizing two important parameters: preconditioning time and co-cultivation time. Agrobacterium tumefaciens-mediated transformation was performed using hypocotyls as explant tissue. Two variants of a green fluorescent protein (GFP)-encoding gene--mGFP5-ER and eGFP--both under the constitutive expression of the cauliflower mosaic virus 35S promoter, were used for the experiments. Optimizing the preconditioning time to 72 h and co-cultivation time with Agrobacterium to 48 h provided the increase in the transformation efficiency from a baseline of 4% to 25%. With mGFP5-ER, the transformation rate was 17% and with eGFP it was 25%. Transgenic shoots were selected on 200 mg/l kanamycin. Rooting efficiency was 100% on half-strength Murashige and Skoog medium with 10 g/l sucrose and 0.5 mg/l indole butyric acid in the presence of kanamycin.

A theoretical study of the omega-phase transformation in metals

NASA Astrophysics Data System (ADS)

Sanati, Mahdi

I have studied the formation of o-phase from electronic and mesoscopic (domain wall) points of view. To study the formation of domain walls, I have extended the Landau model of Cook for the o-phase transition by including a spatial gradient (Ginzburg) term of the scalar order parameter. In general, the Landau free energy is an asymmetric double-well potential. From the variational derivative of the total free energy I obtained a static equilibrium condition. By solving this equation for different physical parameters and boundary conditions, I obtained different quasi-one-dimensional soliton-like solutions. These solutions correspond to three different types of domain walls between the o-phase and the beta-matrix. These results are used to model the formation of the o-phase in bcc Ti. Canonical band model and first principles calculations confirmed the instability of the bcc-phase of group III and IV transition metals with respect to the o-phase transformation. I showed that the d-electron density is the controlling parameter for this type of the transformation. Also the possibility of formation of the o-phase for rare earth metals is discussed. First-principles full-potential linear muffin-tin orbital method (FPLMTO) calculations are performed for o-type displacement of the atoms to study the formation of the o-phase in TiAl and Ti 3Al2Nb alloys. The results of my calculations showed an instability in ordered B2 TiAl structure with respect to the o-phase when one third of the Al atoms are replaced by Nb atoms. These phenomena are explained, first by symmetry arguments; then a pair potential model is used to illustrate this instability based on interactions between different pair of atoms derived from the electronic structure. In addition, importance of the atomic arrangements on the structural stability of the Ti3Al2 Nb system is discussed.

Two-State Reactivity in Low-Valent Iron-Mediated C-H Activation and the Implications for Other First-Row Transition Metals.

PubMed

Sun, Yihua; Tang, Hao; Chen, Kejuan; Hu, Lianrui; Yao, Jiannian; Shaik, Sason; Chen, Hui

2016-03-23

C-H bond activation/functionalization promoted by low-valent iron complexes has recently emerged as a promising approach for the utilization of earth-abundant first-row transition metals to carry out this difficult transformation. Herein we use extensive density functional theory and high-level ab initio coupled cluster calculations to shed light on the mechanism of these intriguing reactions. Our key mechanistic discovery for C-H arylation reactions reveals a two-state reactivity (TSR) scenario in which the low-spin Fe(II) singlet state, which is initially an excited state, crosses over the high-spin ground state and promotes C-H bond cleavage. Subsequently, aryl transmetalation occurs, followed by oxidation of Fe(II) to Fe(III) in a single-electron transfer (SET) step in which dichloroalkane serves as an oxidant, thus promoting the final C-C coupling and finalizing the C-H functionalization. Regeneration of the Fe(II) catalyst for the next round of C-H activation involves SET oxidation of the Fe(I) species generated after the C-C bond coupling. The ligand sphere of iron is found to play a crucial role in the TSR mechanism by stabilization of the reactive low-spin state that mediates the C-H activation. This is the first time that the successful TSR concept conceived for high-valent iron chemistry is shown to successfully rationalize the reactivity for a reaction promoted by low-valent iron complexes. A comparative study involving other divalent middle and late first-row transition metals implicates iron as the optimum metal in this TSR mechanism for C-H activation. It is predicted that stabilization of low-spin Mn(II) using an appropriate ligand sphere should produce another promising candidate for efficient C-H bond activation. This new TSR scenario therefore emerges as a new strategy for using low-valent first-row transition metals for C-H activation reactions.

Metalloproteinase-dependent transforming growth factor-alpha release mediates neurotensin-stimulated MAP kinase activation in human colonic epithelial cells.

PubMed

Zhao, Dezheng; Zhan, Yanai; Koon, Hon Wai; Zeng, Huiyan; Keates, Sarah; Moyer, Mary P; Pothoulakis, Charalabos

2004-10-15

Expression of the neuropeptide neurotensin (NT) and its high affinity receptor (NTR1) is increased during the course of Clostridium difficile toxin A-induced acute colitis, and NTR1 antagonism attenuates the severity of toxin A-induced inflammation. We recently demonstrated in non-transformed human colonic epithelial NCM460 cells that NT treatment caused activation of a Ras-mediated MAP kinase pathway that significantly contributes to NT-induced interleukin-8 (IL-8) secretion. Here we used NCM460 cells, which normally express low levels of NTR1, and NCM460 cells stably transfected with NTR1 to identify the upstream signaling molecules involved in NT-NTR1-mediated MAP kinase activation. We found that inhibition of the epidermal growth factor receptor (EGFR) by either an EGFR neutralizing antibody or by its specific inhibitor AG1478 (0.2 microm) blocked NT-induced MAP kinase activation. Moreover, NT stimulated tyrosine phosphorylation of the EGFR, and pretreatment with a broad spectrum metalloproteinase inhibitor batimastat reduced NT-induced MAP kinase activation. Using neutralizing antibodies against the EGFR ligands EGF, heparin-binding-EGF, transforming growth factor-alpha (TGFalpha), or amphiregulin we have shown that only the anti-TGFalpha antibody significantly decreases NT-induced phosphorylation of EGFR and MAP kinases. Furthermore, inhibition of the EGF receptor by AG1478 significantly reduced NT-induced IL-8 promoter activity and IL-8 secretion. This is the first report demonstrating that NT binding to NTR1 transactivates the EGFR and that this response is linked to NT-mediated proinflammatory signaling. Our findings indicate that matrix metalloproteinase-mediated release of TGFalpha and subsequent EGFR transactivation triggers a NT-mediated MAP kinase pathway that leads to IL-8 gene expression in human colonic epithelial cells.

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: A Review

PubMed Central

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-01-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical, and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter, or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article. PMID:29755967

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: a Review

NASA Astrophysics Data System (ADS)

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-04-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article.

Synergistic Effects among the Structure, Martensite Transformation and Shear Band in a Shape Memory Alloy-Metallic Glass Composite

NASA Astrophysics Data System (ADS)

Zhang, Xudong; Ren, Junqiang; Ding, Xiangdong

2018-05-01

In this work, we use the finite element method to investigate the free volume evolution, as well as the martensite transformation effect and its connection with the pretreatment strain, in a shape memory alloy-metallic glass composite. Our simulation results show that the martensite phase transformation can enhance the blocking effect while relieving the free volume localization. The synergistic effect among the martensite transformation effect, blocking effect, and shear band interaction in the composite is responsible for the tensile plasticity and work-hardening capability. In addition, we design a Sierpinski carpet-like fractal microstructure so that the composite exhibits improved tensile performance as a result of the enhanced synergistic effect. However, the tensile performance of the composite deteriorates with increasing pretreatment strain since the martensite transformation effect is weakened.

SacB-SacR gene cassette as the negative selection marker to suppress Agrobacterium overgrowth in Agrobacterium-mediated plant transformation

USDA-ARS?s Scientific Manuscript database

Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transformation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce ...

Female reproductive tissues are the primary target of Agrobacterium-mediated transformation by the Arabidopsis floral-dip method.

PubMed

Desfeux, C; Clough, S J; Bent, A F

2000-07-01

The floral-dip method for Agrobacterium-mediated transformation of Arabidopsis allows efficient plant transformation without need for tissue culture. To facilitate use with other plant species, we investigated the mechanisms that underlie this method. In manual outcrossing experiments, application of Agrobacterium tumefaciens to pollen donor plants did not produce any transformed progeny, whereas application of Agrobacterium to pollen recipient plants yielded transformants at a rate of 0.48%. Agrobacterium strains with T-DNA carrying gusA (encoding beta-glucuronidase [GUS]) under the control of 35S, LAT52, or ACT11 promoters revealed delivery of GUS activity to developing ovules, whereas no GUS staining of pollen or pollen tubes was observed. Transformants derived from the same seed pod contained independent T-DNA integration events. In Arabidopsis flowers, the gynoecium develops as an open, vase-like structure that fuses to form closed locules roughly 3 d prior to anthesis. In correlation with this fact, we found that the timing of Agrobacterium infection was critical. Transformants were obtained and GUS staining of ovules and embryo sacs was observed only if the Agrobacterium were applied 5 d or more prior to anthesis. A 6-fold higher rate of transformation was obtained with a CRABS-CLAW mutant that maintains an open gynoecium. Our results suggest that ovules are the site of productive transformation in the floral-dip method, and further suggest that Agrobacterium must be delivered to the interior of the developing gynoecium prior to locule closure if efficient transformation is to be achieved.

In Situ Transformation of MOFs into Layered Double Hydroxide Embedded Metal Sulfides for Improved Electrocatalytic and Supercapacitive Performance.

PubMed

Yilmaz, Gamze; Yam, Kah Meng; Zhang, Chun; Fan, Hong Jin; Ho, Ghim Wei

2017-07-01

Direct adoption of metal-organic frameworks (MOFs) as electrode materials shows impoverished electrochemical performance owing to low electrical conductivity and poor chemical stability. In this study, we demonstrate self-templated pseudomorphic transformation of MOF into surface chemistry rich hollow framework that delivers highly reactive, durable, and universal electrochemically active energy conversion and storage functionalities. In situ pseudomorphic transformation of MOF-derived hollow rhombic dodecahedron template and sulfurization of nickel cobalt layered double hydroxides (NiCo-LDHs) lead to the construction of interlayered metal sulfides (NiCo-LDH/Co 9 S 8 ) system. The embedment of metal sulfide species (Co 9 S 8 ) at the LDH intergalleries offers optimal interfacing of the hybrid constituent elements and materials stability. The hybrid NiCo-LDH/Co 9 S 8 system collectively presents an ideal porous structure, rich redox chemistry, and high electrical conductivity matrix. This leads to a significant enhancement in its complementary electrocatalytic hydrogen evolution and supercapacitive energy storage properties. This work establishes the potential of MOF derived scaffold for designing of novel class hybrid inorganic-organic functional materials for electrochemical applications and beyond. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ynamides in Ring Forming Transformations

PubMed Central

WANG, XIAO-NA; YEOM, HYUN-SUK; FANG, LI-CHAO; HE, SHUZHONG; MA, ZHI-XIONG; KEDROWSKI, BRANT L.; HSUNG, RICHARD P.

2013-01-01

Conspectus The ynamide functional group activates carbon-carbon triple bonds through an attached nitrogen atom that bears an electron-withdrawing group. As a result, the alkyne has both electrophilic and nucleophilic properties. Through the selection of the electron-withdrawing group attached to nitrogen chemists can modulate the electronic properties and reactivity of ynamides, making these groups versatile synthetic building blocks. The reactions of ynamides also lead directly to nitrogen-containing products, which provides access to important structural motifs found in natural products and molecules of medicinal interest. Therefore, researchers have invested increasing time and research in the chemistry of ynamides in recent years. This Account surveys and assesses new organic transformations involving ynamides developed in our laboratory and in others around the world. We showcase the synthetic power of ynamides for rapid assembly of complex molecular structures. Among the recent reports of ynamide transformations, ring-forming reactions provide a powerful tool for generating molecular complexity quickly. In addition to their synthetic utility, such reactions are mechanistically interesting. Therefore, we focus primarily on the cyclization chemistry of ynamides. This Account highlights ynamide reactions that are useful in the rapid synthesis of cyclic and polycyclic structural manifolds. We discuss the mechanisms active in the ring formations and describe representative examples that demonstrate the scope of these reactions and provide mechanistic insights. In this discussion we feature examples of ynamide reactions involving radical cyclizations, ring-closing metathesis, transition metal and non-transition metal mediated cyclizations, cycloaddition reactions, and rearrangements. The transformations presented rapidly introduce structural complexity and include nitrogen within, or in close proximity to, a newly formed ring (or rings). Thus, ynamides have emerged

Recent advances in heterobimetallic catalysis across a "transition metal-tin" motif.

PubMed

Das, Debjit; Mohapatra, Swapna Sarita; Roy, Sujit

2015-06-07

Heterobimetallic catalysts, bearing a metal-metal bond between a transition metal (TM) and a tin atom, are very promising due to their ability in mediating a wide variety of organic transformations. Indeed the utilization of such catalysts is a challenging and evolving area in the field of homogeneous catalysis. Catalysis across a 'TM-Sn' motif is an emerging area in the broader domain of multimetallic catalysis. The present review apprises the chemists' community of the past, present and future scope of this versatile catalytic motif. The TM-Sn catalyzed reactions presented include, among others, Friedel-Crafts alkylation, carbonylation, polymerization, cyclization, olefin metathesis, Heck coupling, hydroarylation Michael addition and tandem coupling. The mechanistic aspects of the reactions have been highlighted as well.

Gene regulation mediating fiber-type transformation in skeletal muscle cells is partly glucose- and ChREBP-dependent.

PubMed

Hanke, Nina; Scheibe, Renate J; Manukjan, Georgi; Ewers, David; Umeda, Patrick K; Chang, Kin-Chow; Kubis, Hans-Peter; Gros, Gerolf; Meissner, Joachim D

2011-03-01

Adaptations in the oxidative capacity of skeletal muscle cells can occur under several physiological or pathological conditions. We investigated the effect of increasing extracellular glucose concentration on the expression of markers of energy metabolism in primary skeletal muscle cells and the C2C12 muscle cell line. Growth of myotubes in 25mM glucose (high glucose, HG) compared with 5.55mM led to increases in the expression and activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a marker of glycolytic energy metabolism, while oxidative markers peroxisome proliferator-activated receptor γ coactivator 1α and citrate synthase decreased. HG induced metabolic adaptations as are seen during a slow-to-fast fiber transformation. Furthermore, HG increased fast myosin heavy chain (MHC) IId/x but did not change slow MHCI/β expression. Protein phosphatase 2A (PP2A) was shown to mediate the effects of HG on GAPDH and MHCIId/x. Carbohydrate response element-binding protein (ChREBP), a glucose-dependent transcription factor downstream of PP2A, partially mediated the effects of glucose on metabolic markers. The glucose-induced increase in PP2A activity was associated with an increase in p38 mitogen-activated protein kinase activity, which presumably mediates the increase in MHCIId/x promoter activity. Liver X receptor, another possible mediator of glucose effects, induced only an incomplete metabolic shift, mainly increasing the expression of the glycolytic marker. Taken together, HG induces a partial slow-to-fast transformation comprising metabolic enzymes together with an increased expression of MHCIId/x. This work demonstrates a functional role for ChREBP in determining the metabolic type of muscle fibers and highlights the importance of glucose as a signaling molecule in muscle. Copyright © 2011 Elsevier B.V. All rights reserved.

"We're Trying to Take Action": Transformative Agency, Role Re-Mediation, and the Complexities of Youth Participatory Action Research

ERIC Educational Resources Information Center

Bertrand, Melanie; Durand, E. Sybil; Gonzalez, Taucia

2017-01-01

This article seeks to illuminate the complexity of youth participatory action research (YPAR) through the use of two concepts: (1) transformative agency, a collective initiative to address conflicts and contradictions in activity systems, and (2) role re-mediation, the disruption of power relations. We demonstrate that these concepts, in…

In Situ Monitoring and Modeling of the Solution-Mediated Polymorphic Transformation of Rifampicin: From Form II to Form I.

PubMed

Guo, Nannan; Hou, Baohong; Wang, Na; Xiao, Yan; Huang, Jingjing; Guo, Yanmei; Zong, Shuyi; Hao, Hongxun

2018-01-01

In this article, the solution-mediated polymorphic transformation of rifampicin was investigated and simulated in 3 solvents at 30°C. The solid-state form I and form II of rifampicin was characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). To explore the relative stability, solubility data of form I and form II of rifampicin in butan-1-ol were determined using a dynamical method. In addition, Raman spectroscopy and focused beam reflectance measurement were used to in situ monitor the transformation of rifampicin from form II to form I. The liquid state concentration of rifampicin was measured by UV spectroscopic method. To investigate the effect of solvent on transformation, the transformation experiments were carried out in 3 solvents. Furthermore, a mathematical model was built to describe the kinetics of dissolution, nucleation, and growth processes during transformation by using experimental data. By combination of experimental and simulation results, it was found that the transformation process of rifampicin is controlled by dissolution of form II in heptane, whereas the transformation in hexane and octane was firstly controlled by dissolution of solid-state form and then controlled by growth of form I. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

How Followers Differing in Career Motivation Gain Career Profits from Transformational Leaders: A Longitudinal Moderated Mediation Model.

PubMed

Baethge, Anja; Rigotti, Thomas; Vincent-Hoeper, Sylvie

2017-01-01

Although, transformational leadership is among the most thoroughly examined leadership theories, knowledge regarding its association with followers' career outcomes is still limited. Furthermore, the underlying mechanisms explaining how transformational leaders affect their employees' career success are yet not well-understood. Based on theoretical assumptions about the processes involved in setting the goal of "making a career," we propose an indirect effect of transformational leadership on subjective and objective career success via development opportunities that depends on the level of career motivation of employees. We conducted a longitudinal study with two measurement occasions separated by 13 months with 320 employees of a large IT company. Respondents provided ratings online on their direct supervisor's transformational leadership, their own development opportunities, and career motivation at T1; subjective career success was rated at both time points, whereas objective indicators of career transitions were rated at T2 retrospectively. Using structural equation modeling, we tested the proposed moderated mediation model. The results indicated that transformational leadership increased subordinates' subjective career success via development opportunities. In addition, and contrary to theoretical reasoning, the indirect effect was not significant for employees with high career motivation. Thus, employees high in career motivation appeared not to benefit from the development opportunities offered by transformational leaders. The results are discussed in light of tailored leadership that takes the aspirations, and needs of followers into account.

How Followers Differing in Career Motivation Gain Career Profits from Transformational Leaders: A Longitudinal Moderated Mediation Model

PubMed Central

Baethge, Anja; Rigotti, Thomas; Vincent-Hoeper, Sylvie

2017-01-01

Although, transformational leadership is among the most thoroughly examined leadership theories, knowledge regarding its association with followers' career outcomes is still limited. Furthermore, the underlying mechanisms explaining how transformational leaders affect their employees' career success are yet not well-understood. Based on theoretical assumptions about the processes involved in setting the goal of “making a career,” we propose an indirect effect of transformational leadership on subjective and objective career success via development opportunities that depends on the level of career motivation of employees. We conducted a longitudinal study with two measurement occasions separated by 13 months with 320 employees of a large IT company. Respondents provided ratings online on their direct supervisor's transformational leadership, their own development opportunities, and career motivation at T1; subjective career success was rated at both time points, whereas objective indicators of career transitions were rated at T2 retrospectively. Using structural equation modeling, we tested the proposed moderated mediation model. The results indicated that transformational leadership increased subordinates' subjective career success via development opportunities. In addition, and contrary to theoretical reasoning, the indirect effect was not significant for employees with high career motivation. Thus, employees high in career motivation appeared not to benefit from the development opportunities offered by transformational leaders. The results are discussed in light of tailored leadership that takes the aspirations, and needs of followers into account. PMID:28932204

Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

PubMed Central

Nayak, Nadiya B.; Nayak, Bibhuti B.

2016-01-01

Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications. PMID:27198738

30 CFR 56.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Grounding transformer and switchgear enclosures... MINES Electricity § 56.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 56.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding transformer and switchgear enclosures... MINES Electricity § 56.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 56.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Grounding transformer and switchgear enclosures... MINES Electricity § 56.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 56.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Grounding transformer and switchgear enclosures... MINES Electricity § 56.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 56.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding transformer and switchgear enclosures... MINES Electricity § 56.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

Structural Differentiation between Layered Single (Ni) and Double Metal Hydroxides (Ni–Al LDHs) Using Wavelet Transformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siebecker, Matthew G.; Sparks, Donald L.

2017-09-07

Layered double hydroxides (LDHs) are anionic clays important in disciplines such as environmental chemistry, geochemistry, and materials science. Developments in signal processing of extended X-ray absorption fine structure (EXAFS) data, such as wavelet transformation (WT), have been used to identify transition metals and Al present in the hydroxide sheets of LDHs. The WT plots of LDHs should be distinct from those of isostructural single metal hydroxides. However, no direct comparison of these minerals appears in the literature using WT. This work systematically analyzes a suite of Ni-rich mineral standards, including Ni–Al LDHs, single metal Ni hydroxides, and Ni-rich silicates usingmore » WT. The results illustrate that the WT plots for α-Ni(OH)2 and Ni–Al LDHs are often indistinguishable from each other, with similar two-component plots for the different mineral types. This demonstrates that the WT of the first metal shell often cannot be used to differentiate an LDH from a single metal hydroxide. Interlayer anions adsorbed to the hydroxide sheet of α-Ni(OH)2 affect the EXAFS spectra and are not visible in the FT but are clearly resolved and discrete in the WT.« less

Formation of a new crystalline form of anhydrous β-maltose by ethanol-mediated crystal transformation.

PubMed

Verhoeven, Nicolas; Neoh, Tze Loon; Ohashi, Tetsuya; Furuta, Takeshi; Kurozumi, Sayaka; Yoshii, Hidefumi

2012-04-01

β-Maltose monohydrate was transformed into an anhydrous form by ethanol-mediated method under several temperatures with agitation. A new stable anhydrous form of β-maltose (Mβ(s)) was obtained, as substantiated by the X-ray diffraction patterns. Mβ(s) obtained by this method presented a fine porous structure, resulting in greater specific surface area compared to those of β-maltose monohydrate and anhydrous β-maltose obtained by vacuum drying (Mβ(h)). The crystal transformation presumably consisted of two steps: dehydration reaction from the hydrous to amorphous forms and crystal formation from the amorphous forms to the noble anhydrous form. The kinetics of these reactions were determined by thermal analysis using Jander's equation and Arrhenius plots. The overall activation energies of the dehydration reaction and the formation of anhydrous maltose were evaluated to be 100 and 90 kJ/mol, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Generation of Marker- and/or Backbone-Free Transgenic Wheat Plants via Agrobacterium-Mediated Transformation.

PubMed

Wang, Gen-Ping; Yu, Xiu-Dao; Sun, Yong-Wei; Jones, Huw D; Xia, Lan-Qin

2016-01-01

Horizontal transfer of antibiotic resistance genes to animals and vertical transfer of herbicide resistance genes to the weedy relatives are perceived as major biosafety concerns in genetically modified (GM) crops. In this study, five novel vectors which used gusA and bar as a reporter gene and a selection marker gene, respectively, were constructed based on the pCLEAN dual binary vector system. Among these vectors, 1G7B and 5G7B carried two T-DNAs located on two respective plasmids with 5G7B possessing an additional virGwt gene. 5LBTG154 and 5TGTB154 carried two T-DNAs in the target plasmid with either one or double right borders, and 5BTG154 carried the selectable marker gene on the backbone outside of the T-DNA left border in the target plasmid. In addition, 5BTG154, 5LBTG154, and 5TGTB154 used pAL154 as a helper plasmid which contains Komari fragment to facilitate transformation. These five dual binary vector combinations were transformed into Agrobacterium strain AGL1 and used to transform durum wheat cv Stewart 63. Evaluation of the co-transformation efficiencies, the frequencies of marker-free transgenic plants, and integration of backbone sequences in the obtained transgenic lines indicated that two vectors (5G7B and 5TGTB154) were more efficient in generating marker-free transgenic wheat plants with no or minimal integration of backbone sequences in the wheat genome. The vector series developed in this study for generation of marker- and/or backbone-free transgenic wheat plants via Agrobacterium -mediated transformation will be useful to facilitate the creation of "clean" GM wheat containing only the foreign genes of agronomic importance.

30 CFR 57.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Grounding transformer and switchgear enclosures... NONMETAL MINES Electricity Surface and Underground § 57.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 57.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding transformer and switchgear enclosures... NONMETAL MINES Electricity Surface and Underground § 57.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 57.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Grounding transformer and switchgear enclosures... NONMETAL MINES Electricity Surface and Underground § 57.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 57.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding transformer and switchgear enclosures... NONMETAL MINES Electricity Surface and Underground § 57.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

30 CFR 57.12026 - Grounding transformer and switchgear enclosures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Grounding transformer and switchgear enclosures... NONMETAL MINES Electricity Surface and Underground § 57.12026 Grounding transformer and switchgear enclosures. Metal fencing and metal buildings enclosing transformers and switchgear shall be grounded. ...

Agrobacterium tumefaciens-mediated transformation of Campanula carpatica: factors affecting transformation and regeneration of transgenic shoots.

PubMed

Sriskandarajah, Sridevy; Frello, Stefan; Jørgensen, Kirsten; Serek, Margrethe

2004-08-01

An efficient transformation system for Campanula carpatica was developed using Agrobacterium tumefaciens strains LBA4404 (harbouring the plasmid pBI121), and AGL0 (harbouring the plasmid pBEO210). This is the first report on the transformation of C. carpatica. Various factors affecting the transformation efficiency and subsequent regeneration were identified. The age of seedlings from which the explants for transformation studies were taken, and the growth conditions under which the seedlings were grown had a significant influence on the production of transformed shoots. Hypocotyls taken from 12-day-old seedlings grown in the dark were the most productive, with up to 25% of hypocotyls producing transformed shoots. Explants taken from 5-week-old seedlings produced only transformed callus. The medium used for co-cultivation and incubation also had a significant influence on transformation frequency and shoot regeneration. The cultivar "Blue Uniform" was more responsive than "White Uniform". Both bacterial strains and plasmids were equally effective in producing transformed tissue. Transformed shoots were selected on kanamycin medium, and the presence of the uidA and nptII genes in those selected shoots was confirmed by beta-glucuronidase and ELISA analyses, respectively.

Female Reproductive Tissues Are the Primary Target of Agrobacterium-Mediated Transformation by the Arabidopsis Floral-Dip Method1

PubMed Central

Desfeux, Christine; Clough, Steven J.; Bent, Andrew F.

2000-01-01

The floral-dip method for Agrobacterium-mediated transformation of Arabidopsis allows efficient plant transformation without need for tissue culture. To facilitate use with other plant species, we investigated the mechanisms that underlie this method. In manual outcrossing experiments, application of Agrobacterium tumefaciens to pollen donor plants did not produce any transformed progeny, whereas application of Agrobacterium to pollen recipient plants yielded transformants at a rate of 0.48%. Agrobacterium strains with T-DNA carrying gusA (encoding β-glucuronidase [GUS]) under the control of 35S, LAT52, or ACT11 promoters revealed delivery of GUS activity to developing ovules, whereas no GUS staining of pollen or pollen tubes was observed. Transformants derived from the same seed pod contained independent T-DNA integration events. In Arabidopsis flowers, the gynoecium develops as an open, vase-like structure that fuses to form closed locules roughly 3 d prior to anthesis. In correlation with this fact, we found that the timing of Agrobacterium infection was critical. Transformants were obtained and GUS staining of ovules and embryo sacs was observed only if the Agrobacterium were applied 5 d or more prior to anthesis. A 6-fold higher rate of transformation was obtained with a CRABS-CLAW mutant that maintains an open gynoecium. Our results suggest that ovules are the site of productive transformation in the floral-dip method, and further suggest that Agrobacterium must be delivered to the interior of the developing gynoecium prior to locule closure if efficient transformation is to be achieved. PMID:10889238

Factors affecting the efficient transformation of Colletotrichum species

USGS Publications Warehouse

Redman, Regina S.; Rodriguez, Rusty J.

1994-01-01

Factors affecting the efficient transformation of Colletotrichum species. Experimental Mycology, 18, 230-246. Twelve isolates representing four species of Colletotrichum were transformed either by enhanced protoplast, restriction enzyme-mediated integration (REMI), or electroporation-mediated protocols. The enhanced protoplast transformation protocol resulted in 100- and 50-fold increases in the transformation efficiencies of Colletotrichum lindemuthianum and C. magna , respectively. REMI transformation involved the use of Hin dIII and vector DNA linearized with HindIII to increase the number of integration events and potential gene disruptions in the fungal genome. Combining the enhanced protoplast and the REMI protocols resulted in a 22-fold increase in the number of hygromycin/nystatin-resistant mutants in C. lindemuthianum . Electroporation-mediated transformation was performed on mycelial fragments and spores of four Colletotrichum species, resulting in efficiencies of up to 1000 transformants/μg DNA. The pHA1.3 vector which confers hygromycin resistance contains telomeric sequences from Fusarium oxysporum , transforms by autonomous replication and genomic integration, and was essential for elevated transformation efficiencies of 100 to 10,000 transformants/μg DNA. Modifications of pHA1.3 occurred during bacterial amplification and post fungal transformation resulting in plasmids capable of significantly elevated transformation efficiencies in C. lindemuthianum.

Selective inhibition of CTCF binding by iAs directs TET-mediated reprogramming of 5-hydroxymethylation patterns in iAs-transformed cells

PubMed Central

Rea, Matthew; Gripshover, Tyler; Fondufe-Mittendorf, Yvonne

2017-01-01

Methylation at cytosine (5mC) is a fundamental epigenetic DNA modification recently associated with iAs-mediated carcinogenesis. In contrast, the role of 5-hydroxymethylcytosine (5hmC), the oxidation product of 5mC in iAs-mediated carcinogenesis is unknown. Here we assess the hydroxymethylome in iAs-transformed cells, showing that dynamic modulation of hydroxymethylated DNA is associated with specific transcriptional networks. Moreover, this pathologic iAs-mediated carcinogenesis is characterized by a shift toward a higher hydroxymethylation pattern genome-wide. At specific promoters, hydroxymethylation correlated with increased gene expression. Furthermore, this increase in hydroxymethylation occurs concurrently with an upregulation of ten-eleven translocation (TET) enzymes that oxidize 5-methylcytosine (5mC) in DNA. To gain an understanding into how iAs might impact TET expression, we found that iAs inhibits the binding of CTCF at the proximal, weak CTCF binding sites of the TET1 and TET2 gene promoters and enhances CTCF binding at the stronger distal binding site. Further analyses suggest that this distal site acts as an enhancer, thus high CTCF occupancy at the enhancer region of TET1 and TET2 possibly drives their high expression in iAs-transformed cells. These results have major implications in understanding the impact of differential CTCF binding, genome architecture and its consequences in iAs-mediated pathogenesis. PMID:29175454

piggybac- and PhiC31-Mediated Genetic Transformation of the Asian Tiger Mosquito, Aedes albopictus (Skuse)

PubMed Central

Labbé, Geneviève M. C.; Nimmo, Derric D.; Alphey, Luke

2010-01-01

Background The Asian tiger mosquito, Aedes albopictus (Skuse), is a vector of several arboviruses including dengue and chikungunya. This highly invasive species originating from Southeast Asia has travelled the world in the last 30 years and is now established in Europe, North and South America, Africa, the Middle East and the Caribbean. In the absence of vaccine or antiviral drugs, efficient mosquito control strategies are crucial. Conventional control methods have so far failed to control Ae. albopictus adequately. Methodology/Principal Findings Germline transformation of Aedes albopictus was achieved by micro-injection of embryos with a piggyBac-based transgene carrying a 3xP3-ECFP marker and an attP site, combined with piggyBac transposase mRNA and piggyBac helper plasmid. Five independent transgenic lines were established, corresponding to an estimated transformation efficiency of 2–3%. Three lines were re-injected with a second-phase plasmid carrying an attB site and a 3xP3-DsRed2 marker, combined with PhiC31 integrase mRNA. Successful site-specific integration was observed in all three lines with an estimated transformation efficiency of 2–6%. Conclusions/Significance Both piggybac- and site-specific PhiC31-mediated germline transformation of Aedes albopictus were successfully achieved. This is the first report of Ae. albopictus germline transformation and engineering, a key step towards studying and controlling this species using novel molecular techniques and genetic control strategies. PMID:20808959

The mediating effects of team and self-efficacy on the relationship between transformational leadership, and job satisfaction and psychological well-being in healthcare professionals: a cross-sectional questionnaire survey.

PubMed

Nielsen, Karina; Yarker, Joanna; Randall, Raymond; Munir, Fehmidah

2009-09-01

The importance of transformational leadership for the health and well-being of staff in the healthcare sector is increasingly acknowledged, however, there is less knowledge about the mechanisms that may explain the links between transformational leaders and employee health and well-being. To examine two possible psychological mechanisms that link transformational leadership behaviours to employee job satisfaction and well-being. Cross-sectional study design. The study took place in two elderly care centers in large Danish local government. Staff were predominantly healthcare assistants but also nurses and other healthcare-related professions participated in the study. 274 elderly care employees completed the questionnaire. Surveys were sent to all employees working at the centers. 91% were female, the average age was 45 years. A questionnaire was distributed to all members of staff in the elderly care centers and where employees were asked to rate their line manager's leadership style and were asked to evaluate their own level of self-efficacy as well as the level of efficacy in their team (team efficacy) and their job satisfaction and psychological well-being. Both team and self-efficacy were found to act as mediators, however, their effects differed. Self-efficacy was found to fully mediate the relationship between transformational leadership and well-being and team efficacy was found to partially mediate the relationship between transformational leadership and job satisfaction and fully mediate the relationship between transformational leadership and well-being. Within the pressurised environment faced by employees in the healthcare sector today transformational leaders may help ensure employees' job satisfaction and psychological well-being. They do so through the establishment of a sense of being in control as individuals but also as being part of a competent group.

Changing stress while stressing change: the role of interprofessional education in mediating stress in the introduction of a transformative technology.

PubMed

Gillan, Caitlin; Wiljer, David; Harnett, Nicole; Briggs, Kaleigh; Catton, Pamela

2010-11-01

The introduction of a transformative technology into practice settings can affect the functioning of interprofessional teams, placing stress on interprofessional relationships, thus slowing adoption and change. This study explored the potential of an interprofessional education (IPE) approach to mediate this stress and facilitate the adoption of a transformative technology- Image Guided Radiation Therapy (IGRT). Oncologists, physicists, and therapists in radiation medicine who attended an interprofessional IGRT Education Course were interviewed about perceived benefits and stressors to IPE and to interprofessional practice (IPP) in the IGRT context. A modified grounded theory approach was used to conduct 14 interviews, with 200 minutes of interview time recorded. In introducing IGRT, participants noted interprofessional stress in understanding and adopting new technology. IPE offered common terminology, appreciation for others' knowledge, and a holistic framework for practice. Outcomes were thought to foster collaboration, efficiency, and improved professional role definition. Time constraints and power relations were noted to be residual stressors exacerbated by IPE, but were thought to be transient. IPE can thus be of benefit in the implementation of transformative technologies such as IGRT, through mediation of interprofessional stress inherent in change. Interprofessional knowledge, collaboration, and efficiency in practice facilitate the development and adoption of a new practice model.

c-Jun/AP-1 pathway-mediated cyclin D1 expression participates in low dose arsenite-induced transformation in mouse epidermal JB6 Cl41 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Dongyun; Li Jingxia; Gao Jimin

2009-02-15

Arsenic is a well-documented human carcinogen associated with skin carcinogenesis. Our previous work reveals that arsenite exposure is able to induce cell transformation in mouse epidermal cell JB6 Cl41 through the activation of ERK, rather than JNK pathway. Our current studies further evaluate downstream pathway in low dose arsenite-induced cell transformation in JB6 Cl41 cells. Our results showed that treatment of cells with low dose arsenite induced activation of c-Jun/AP-1 pathway, and ectopic expression of dominant negative mutant of c-Jun (TAM67) blocked arsenite-induced transformation. Furthermore, our data indicated that cyclin D1 was an important downstream molecule involved in c-Jun/AP-1-mediated cellmore » transformation upon low dose arsenite exposure, because inhibition of cyclin D1 expression by its specific siRNA in the JB6 Cl41 cells resulted in impairment of anchorage-independent growth of cells induced by low dose arsenite. Collectively, our results demonstrate that c-Jun/AP-1-mediated cyclin D1 expression is at least one of the key events implicated in cell transformation upon low dose arsenite exposure.« less

The PDZ-binding motif of Yes-associated protein is required for its co-activation of TEAD-mediated CTGF transcription and oncogenic cell transforming activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shimomura, Tadanori; Miyamura, Norio; Hata, Shoji

2014-01-17

Highlights: •Loss of the PDZ-binding motif inhibits constitutively active YAP (5SA)-induced oncogenic cell transformation. •The PDZ-binding motif of YAP promotes its nuclear localization in cultured cells and mouse liver. •Loss of the PDZ-binding motif inhibits YAP (5SA)-induced CTGF transcription in cultured cells and mouse liver. -- Abstract: YAP is a transcriptional co-activator that acts downstream of the Hippo signaling pathway and regulates multiple cellular processes, including proliferation. Hippo pathway-dependent phosphorylation of YAP negatively regulates its function. Conversely, attenuation of Hippo-mediated phosphorylation of YAP increases its ability to stimulate proliferation and eventually induces oncogenic transformation. The C-terminus of YAP contains amore » highly conserved PDZ-binding motif that regulates YAP’s functions in multiple ways. However, to date, the importance of the PDZ-binding motif to the oncogenic cell transforming activity of YAP has not been determined. In this study, we disrupted the PDZ-binding motif in the YAP (5SA) protein, in which the sites normally targeted by Hippo pathway-dependent phosphorylation are mutated. We found that loss of the PDZ-binding motif significantly inhibited the oncogenic transformation of cultured cells induced by YAP (5SA). In addition, the increased nuclear localization of YAP (5SA) and its enhanced activation of TEAD-dependent transcription of the cell proliferation gene CTGF were strongly reduced when the PDZ-binding motif was deleted. Similarly, in mouse liver, deletion of the PDZ-binding motif suppressed nuclear localization of YAP (5SA) and YAP (5SA)-induced CTGF expression. Taken together, our results indicate that the PDZ-binding motif of YAP is critical for YAP-mediated oncogenesis, and that this effect is mediated by YAP’s co-activation of TEAD-mediated CTGF transcription.« less

Nano-fabricated plasmonic optical transformer

DOEpatents

Choo, Hyuck; Cabrini, Stefano; Schuck, P. James; Liang, Xiaogan; Yablonovitch, Eli

2015-06-09

The present invention provides a plasmonic optical transformer to produce a highly focuses optical beam spot, where the transformer includes a first metal layer, a dielectric layer formed on the first metal layer, and a second metal layer formed on the dielectric layer, where the first metal layer, the dielectric layer, and the second layer are patterned to a shape including a first section having a first cross section, a second section following the first section having a cross-section tapering from the first section to a smaller cross-section, and a third section following the second section having a cross-section matching the tapered smaller cross-section of the second section.

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

PubMed Central

Engelen, Bernward; Panthöfer, Martin; Deiseroth, Hans-Jörg; Schlirf, Jens

2016-01-01

Summary A one-pot transformation, which involves the reaction of ketones with aldehydes in the presence of metal halides to furnish tetrahydro-2H-pyran-2,4-diols in a highly diastereoselective manner, is investigated thoroughly by experiments and computations. The reaction was also successfully implemented on a flow micro reactor system. PMID:27340472

Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bharti, Amardeep, E-mail: abharti@pu.ac.in; Goyal, Navdeep; Singh, Suman

Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

Integrin-Mediated Transforming Growth Factor-β Activation Regulates Homeostasis of the Pulmonary Epithelial-Mesenchymal Trophic Unit

PubMed Central

Araya, Jun; Cambier, Stephanie; Morris, Alanna; Finkbeiner, Walter; Nishimura, Stephen L.

2006-01-01

Trophic interactions between pulmonary epithelial and mesenchymal cell types, known as the epithelial-mesenchymal trophic unit (EMTU), are crucial in lung development and lung disease. Transforming growth factor (TGF)-β is a key factor in mediating these interactions, but it is expressed in a latent form that requires activation to be functional. Using intact fetal tracheal tissue and primary cultures of fetal tracheal epithelial cells and fibroblasts, we demonstrate that a subset of integrins, αvβ6 and αvβ8, are responsible for almost all of the TGF-β activation in the EMTU. Both αvβ8 and αvβ6 contribute to fetal tracheal epithelial activation of TGF-β, whereas only αvβ8 contributes to fetal tracheal fibroblast activation of TGF-β. Interestingly, fetal tracheal epithelial αvβ8-mediated TGF-β activation can be enhanced by phorbol esters, likely because of the increased activity of MT1-MMP, an essential co-factor in αvβ8-mediated activation of TGF-β. Autocrine αvβ8-mediated TGF-β activation by fetal tracheal fibroblasts results in suppression of both transcription and secretion of hepatocyte growth factor, which is sufficient to affect phosphorylation of the airway epithelial hepatocyte growth factor receptor, c-Met, as well as airway epithelial proliferation in a co-culture model of the EMTU. These findings elucidate the function and complex regulation of integrin-mediated activation of TGF-β within the EMTU. PMID:16877343

Integrin-mediated transforming growth factor-beta activation regulates homeostasis of the pulmonary epithelial-mesenchymal trophic unit.

PubMed

Araya, Jun; Cambier, Stephanie; Morris, Alanna; Finkbeiner, Walter; Nishimura, Stephen L

2006-08-01

Trophic interactions between pulmonary epithelial and mesenchymal cell types, known as the epithelial-mesenchymal trophic unit (EMTU), are crucial in lung development and lung disease. Transforming growth factor (TGF)-beta is a key factor in mediating these interactions, but it is expressed in a latent form that requires activation to be functional. Using intact fetal tracheal tissue and primary cultures of fetal tracheal epithelial cells and fibroblasts, we demonstrate that a subset of integrins, alpha(v)beta(6) and alpha(v)beta(8), are responsible for almost all of the TGF-beta activation in the EMTU. Both alpha(v)beta(8) and alpha(v)beta(6) contribute to fetal tracheal epithelial activation of TGF-beta, whereas only alpha(v)beta(8) contributes to fetal tracheal fibroblast activation of TGF-beta. Interestingly, fetal tracheal epithelial alpha(v)beta(8)-mediated TGF-beta activation can be enhanced by phorbol esters, likely because of the increased activity of MT1-MMP, an essential co-factor in alpha(v)beta(8)-mediated activation of TGF-beta. Autocrine alpha(v)beta(8)-mediated TGF-beta activation by fetal tracheal fibroblasts results in suppression of both transcription and secretion of hepatocyte growth factor, which is sufficient to affect phosphorylation of the airway epithelial hepatocyte growth factor receptor, c-Met, as well as airway epithelial proliferation in a co-culture model of the EMTU. These findings elucidate the function and complex regulation of integrin-mediated activation of TGF-beta within the EMTU.

Microstructural evolution in ultra-low-carbon steel weldments—Part I: Controlled thermal cycling and continuous cooling transformation diagram of the weld metal

NASA Astrophysics Data System (ADS)

Fonda, R. W.; Spanos, G.

2000-09-01

The transformation behavior and microstructural evolution of the as-deposited weld metal from an ultra-low-carbon (ULC) weldment were characterized by dilatometry, optical microscopy, transmission electron microscopy, and microhardness measurements. These results were used to construct a continuous cooling transformation (CCT) diagram for this weld metal. The major microconstituents observed in this ULC weldment were (in order of decreasing cooling rate) coarse autotempered martensite, fine lath martensite, lath ferrite, and degenerate lath ferrite. No polygonal ferrite was observed. These results were also used to develop criteria to differentiate between the two predominant microstructures in these ULC steels, lath martensite, and lath ferrite, which can look quite similar but have very different properties.

Solution-mediated phase transformation of haloperidol mesylate in the presence of sodium lauryl sulfate.

PubMed

Greco, Kristyn; Bogner, Robin

2011-09-01

Forming a salt is a common way to increase the solubility of a poorly soluble compound. However, the solubility enhancement gained by salt formation may be lost due to solution-mediated phase transformation (SMPT) during dissolution. The SMPT of a salt can occur due to a supersaturated solution near the dissolving surface caused by pH or other solution conditions. In addition to changes in pH, surfactants are also known to affect SMPT. In this study, SMPT of a highly soluble salt, haloperidol mesylate, at pH 7 in the presence of a commonly used surfactant, sodium lauryl sulfate (SLS), was investigated. Dissolution experiments were performed using a flow-through dissolution apparatus with solutions containing various concentrations of SLS. Compacts of haloperidol mesylate were observed during dissolution in the flow-through apparatus using a stereomicroscope. Raman microscopy was used to characterize solids. The dissolution of haloperidol mesylate was significantly influenced by the addition of sodium lauryl sulfate. In conditions where SMPT was expected, the addition of SLS at low concentrations (0.1-0.2 mM) reduced the dissolution of haloperidol mesylate. In solutions containing concentrations of SLS above the critical micelle concentration (CMC) (10-15 mM), the dissolution of haloperidol mesylate increased compared to below the CMC. The solids recovered from solubility experiments of haloperidol mesylate indicated that haloperidol free base precipitated at all concentrations of SLS. Above 5 mM of SLS, Raman microscopy suggested a new form, perhaps the estolate salt. The addition of surfactant in solids that undergo solution-mediated phase transformation can add complexity to the dissolution profiles and conversion.

Forms of Mediation: The Case of Interpreter-Mediated Interactions in Medical Systems

ERIC Educational Resources Information Center

Baraldi, Claudio

2009-01-01

This paper analyses the forms of mediation in interlinguistic interactions performed in Italian healthcare services and in contexts of migration. The literature encourages dialogic transformative mediation, empowering participants' voices and changing cultural presuppositions in social systems. It may be doubtful, however, whether mediation can…

Ecological risk assessment on heavy metals in soils: Use of soil diffuse reflectance mid-infrared Fourier-transform spectroscopy

PubMed Central

Wang, Cheng; Li, Wei; Guo, Mingxing; Ji, Junfeng

2017-01-01

The bioavailability of heavy metals in soil is controlled by their concentrations and soil properties. Diffuse reflectance mid-infrared Fourier-transform spectroscopy (DRIFTS) is capable of detecting specific organic and inorganic bonds in metal complexes and minerals and therefore, has been employed to predict soil composition and heavy metal contents. The present study explored the potential of DRIFTS for estimating soil heavy metal bioavailability. Soil and corresponding wheat grain samples from the Yangtze River Delta region were analyzed by DRIFTS and chemical methods. Statistical regression analyses were conducted to correlate the soil spectral information to the concentrations of Cd, Cr, Cu, Zn, Pb, Ni, Hg and Fe in wheat grains. The principal components in the spectra influencing soil heavy metal bioavailability were identified and used in prediction model construction. The established soil DRIFTS-based prediction models were applied to estimate the heavy metal concentrations in wheat grains in the mid-Yangtze River Delta area. The predicted heavy metal concentrations of wheat grain were highly consistent with the measured levels by chemical analysis, showing a significant correlation (r2 > 0.72) with acceptable root mean square error RMSE. In conclusion, DRIFTS is a promising technique for assessing the bioavailability of soil heavy metals and related ecological risk. PMID:28198802

Cavitation instability in bulk metallic glasses

NASA Astrophysics Data System (ADS)

Dai, L. H.; Huang, X.; Ling, Z.

2015-09-01

Recent experiments have shown that fracture surfaces of bulk metallic glasses (BMGs) usually exhibit an intriguing nanoscale corrugation like fractographic feature mediated by nanoscale void formation. We attribute the onset of this nanoscale corrugation to TTZs (tension transformation zones) mediated cavitation. In our recent study, the spall experiments of Zr-based BMG using a single-stage light gas gun were performed. To uncover the mechanisms of the spallation damage nucleation and evolution, the samples were designed to be subjected to dynamic tensile loadings of identical amplitude but with different durations by making use of the multi-stress pulse and the double-flyer techniques. It is clearly revealed that the macroscopic spall fracture in BMGs originates from the nucleation, growth and coalescence of micro-voids. Then, a microvoid nucleation model of BMGs based on free volume theory is proposed, which indicates that the nucleation of microvoids at the early stage of spallation in BMGs is resulted from diffusion and coalescence of free volume. Furthermore, a theoretical model of void growth in BMGs undergoing remote dynamic hydrostatic tension is developed. The critical condition of cavitation instability is obtained. It is found that dynamic void growth in BMGs can be well controlled by a dimensionless inertial number characterizing the competition between intrinsic and extrinsic time scales. To unveil the atomic-level mechanism of cavitation, a systematic molecular dynamics (MD) simulation of spallation behaviour of a binary metallic glass with different impact velocities was performed. It is found that micro-void nucleation is determined TTZs while the growth is controlled by shear transformation zones (STZs) at atomic scale.

Fluid mediated transformation of aragonitic cuttlebone to calcite

NASA Astrophysics Data System (ADS)

Perdikouri, C.; Kasioptas, A.; Putnis, A.

2009-04-01

The aragonite to calcite transition has been studied extensively over the years because of its wide spectra of applications and of its significant geochemical interest. While studies of kinetics (e.g. Topor et al., 1981), thermodynamics (e.g. Wolf et al., 1996) and behavior of ions such as Sr and Mg (e.g. Yoshioka et al., 1986) have been made there are still unanswered questions regarding this reaction especially in the cases where the effects of fluid composition are considered. It is well known that when heated in air, aragonite transforms by a solid state reaction to calcite. The aragonite cuttlebone of the sepia officinalis that was used for our experiments undergoes a phase transition at ~370-390˚ C, measured by in situ heating experiments in a Philips X'pert X-ray powder diffractometer equipped with a HTK 1200 High temperature oven. Successive X-ray scans were taken at isothermal temperatures at 200C intervals. A similar temperature range was found by Vongsavat et al. 2006, who studied this transition in Acropora corals. It is possible however to promote this transition at considerably lower temperatures by means of a fluid mediated reaction where the replacement takes place by a dissolution-precipitation mechanism (Putnis & Putnis, 2007). We have successfully carried out hydrothermal experiments where cuttlebone has been converted to calcite at 200˚ C. Using the PhreeqC program we calculated the required composition of a solution that would be undersaturated with respect to aragonite and saturated with respect to calcite leading to dissolution of the aragonite and to a consequent precipitation of the new calcite phase, similar to the experiments described in an earlier study (Perdikouri et al, 2008). This reaction is not pseudomorphic and results in the destruction of the morphology, presumably due to the molar volume increase. A total transformation of the cuttlebone produced a fine calcite powder. The cuttlebone exhibits a unique microstructure, made

An efficient and high-throughput protocol for Agrobacterium-mediated transformation based on phosphomannose isomerase positive selection in Japonica rice (Oryza sativa L.).

PubMed

Duan, Yongbo; Zhai, Chenguang; Li, Hao; Li, Juan; Mei, Wenqian; Gui, Huaping; Ni, Dahu; Song, Fengshun; Li, Li; Zhang, Wanggen; Yang, Jianbo

2012-09-01

A number of Agrobacterium-mediated rice transformation systems have been developed and widely used in numerous laboratories and research institutes. However, those systems generally employ antibiotics like kanamycin and hygromycin, or herbicide as selectable agents, and are used for the small-scale experiments. To address high-throughput production of transgenic rice plants via Agrobacterium-mediated transformation, and to eliminate public concern on antibiotic markers, we developed a comprehensive efficient protocol, covering from explant preparation to the acquisition of low copy events by real-time PCR analysis before transplant to field, for high-throughput production of transgenic plants of Japonica rice varieties Wanjing97 and Nipponbare using Escherichia coli phosphomannose isomerase gene (pmi) as a selectable marker. The transformation frequencies (TF) of Wanjing97 and Nipponbare were achieved as high as 54.8 and 47.5%, respectively, in one round of selection of 7.5 or 12.5 g/L mannose appended with 5 g/L sucrose. High-throughput transformation from inoculation to transplant of low copy events was accomplished within 55-60 days. Moreover, the Taqman assay data from a large number of transformants showed 45.2% in Wanjing97 and 31.5% in Nipponbare as a low copy rate, and the transformants are fertile and follow the Mendelian segregation ratio. This protocol facilitates us to perform genome-wide functional annotation of the open reading frames and utilization of the agronomically important genes in rice under a reduced public concern on selectable markers. We describe a comprehensive protocol for large scale production of transgenic Japonica rice plants using non-antibiotic selectable agent, at simplified, cost- and labor-saving manners.

Efficient and rapid Agrobacterium-mediated genetic transformation of durum wheat (Triticum turgidum L. var. durum) using additional virulence genes.

PubMed

Wu, Huixia; Doherty, Angela; Jones, Huw D

2008-06-01

Genetic transformation of wheat, using biolistics or Agrobacterium, underpins a range of specific research methods for identifying genes and studying their function in planta. Transgenic approaches to study and modify traits in durum wheat have lagged behind those for bread wheat. Here we report the use of Agrobacterium strain AGL1, with additional vir genes housed in a helper plasmid, to transform and regenerate the durum wheat variety Ofanto. The use of the basic pSoup helper plasmid with no additional vir genes failed to generate transformants, whereas the presence of either virG542 or the 15 kb Komari fragment containing virB, virC and virG542 produced transformation efficiencies of between 0.6 and 9.7%. Of the 42 transgenic plants made, all but one (which set very few seeds) appeared morphologically normal and produced between 100 and 300 viable seeds. The transgene copy number and the segregation ratios were found to be very similar to those previously reported for bread wheat. We believe that this is the first report describing successful genetic transformation of tetraploid durum wheat (Triticum turgidum L. var. durum) mediated by Agrobacterium tumefaciens using immature embryos as the explant.

14-3-3 sigma and 14-3-3 zeta plays an opposite role in cell growth inhibition mediated by transforming growth factor-beta 1.

PubMed

Hong, Hye-Young; Jeon, Woo-Kwang; Bae, Eun-Jin; Kim, Shin-Tae; Lee, Ho-Jae; Kim, Seong-Jin; Kim, Byung-Chul

2010-03-01

The expression of 14-3-3 proteins is dysregulated in various types of cancer. This study was undertaken to investigate the effects of 14-3-3 zeta and 14-3-3 sigma on cell growth inhibition mediated by transforming growth factor-beta 1 (TGF-beta1). Mouse mammary epithelial cells (Eph4) that are transformed with oncogenic c-H-Ras (EpRas) and no longer sensitive to TGF-beta1-mediated growth inhibition displayed increased expression of 14-3-3 zeta and decreased expression of 14-3-3 sigma compared with parental Eph4 cells. Using small interfering RNA-mediated knockdown and overexpression of 14-3-3 sigma or 14-3-3 zeta, we showed that 14-3-3 sigma is required for TGF-beta1-mediated growth inhibition whereas 14-3-3 zeta negatively modulates this growth inhibitory response. Notably, overexpression of 14-3-3 zeta increased the level of Smad3 protein that is phosphorylated at linker regions and cannot mediate the TGF-beta1 growth inhibitory response. Consistent with this finding, mutation of the 14-3-3 zeta phosphorylation sites in Smad3 markedly reduced the 14-3-3 zeta-mediated inhibition of TGF-beta1-induced p15 promoter-reporter activity and cell cycle arrest, suggesting that these residues are critical targets of 14-3-3 zeta in the suppression of TGF-beta1-mediated growth. Taken together, our findings indicate that dysregulation of 14-3-3 sigma or 14-3-3 zeta contributes to TGF-beta1 resistance in cancer cells.

Studies of transformational leadership in the consumer service workgroup: cooperative conflict resolution and the mediating roles of job satisfaction and change commitment.

PubMed

Yang, Yi-Feng

2012-10-01

The present paper evaluates the effect of transformational leadership on job satisfaction and change commitment along with their interconnected effects (mediation) on cooperative conflict resolution (management) in customer service activities in Taiwan. The multi-source samples consist of data from personnel serving at customer centers (workgroups), such as phone service personnel, customer representatives, financial specialists, and front-line salespeople. An empirical study was carried out using a multiple mediation procedure incorporating boot-strapping techniques and PRODCLIN2 with structural equation modeling (SEM) analysis. The results indicate that the main effect of the leadership style on cooperative conflict resolution is mediated by change commitment and job satisfaction.

Wheat (Triticum aestivum L.) transformation using mature embryos.

PubMed

Medvecká, Eva; Harwood, Wendy A

2015-01-01

In most protocols for the Agrobacterium-mediated transformation of wheat, the preferred target tissues are immature embryos. However, transformation methods relying on immature embryos require the growth of plants under controlled conditions to provide a continuous supply of good-quality target tissue. The use of mature embryos as a target tissue has the advantage of only requiring good-quality seed as the starting material. Here we describe a transformation method based on the Agrobacterium-mediated transformation of callus cultures derived from mature wheat embryos of the genotype Bobwhite S56.

Transition Metal Polypyridine Complexes: Studies of Mediation in Dye-Sensitized Solar Cells and Charge Separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, C. Michael; Prieto, Amy L.

2017-02-08

The Elliott group has long been supported by DOE for studies of cobalt(II/III) trisbypiridine (DTB) mediator complexes in dye sensitized solar cells. Previous work demonstrated that Co(II/III) chemistry is sensitive to the environment, showing unprecedented electrode-surface and electrolyte dependant voltammetry. In electrolytes that have large lipophilic cations, voltammetry of the [Co(DTB) 3] 2+/3+ couple is nearly Nernstian in appearance on nominally oxide-free metal surfaces. In contrast, on semiconductor electrodes in electrolytes with small, hard cations such as Li +, the electron transfer rates are so slow that it is difficult to measure any Faradaic current even at overpotentials of ±1more » V. These studies are of direct relevance to the operation of cobalt-based mediators in solar cells. The research has also shown that these mediators are compatible with copper phenantroline based dyes, in contrast to I - due to the insolubility of CuI.« less

Phase Transformations and Microstructural Evolution: Part I

DOE PAGES

Clarke, Amy Jean

2015-08-29

The activities of the Phase Transformations Committee of the Materials Processing & Manufacturing Division (MPMD) of The Minerals, Metals & Materials Society (TMS) are oriented toward understanding the fundamental aspects of phase transformations. Emphasis is placed on the thermodynamic driving forces for phase transformations, the kinetics of nucleation and growth, interfacial structures and energies, transformation crystallography, surface reliefs, and, above all, the atomic mechanisms of phase transformations. Phase transformations and microstructural evolution are directly linked to materials processing, properties, and performance, including in extreme environments, of structural metal alloys. In this paper, aspects of phase transformations and microstructural evolution aremore » highlighted from the atomic to the microscopic scale for ferrous and non-ferrous alloys. Many papers from this issue are highlighted with small summaries of their scientific achievements given.« less

Effects of medium and trace metals on kinetics of carbon tetrachloride transformation by Pseudomonas sp. strain KC.

PubMed Central

Tatara, G M; Dybas, M J; Criddle, C S

1993-01-01

Under denitrifying conditions, Pseudomonas sp. strain KC transforms carbon tetrachloride (CT) to carbon dioxide via a complex but as yet undetermined mechanism. Transformation rates were first order with respect to CT concentration over the CT concentration range examined (0 to 100 micrograms/liter) and proportional to protein concentration, giving pseudo-second-order kinetics overall. Addition of ferric iron (1 to 20 microM) to an actively transforming culture inhibited CT transformation, and the degree of inhibition increased with increasing iron concentration. By removing iron from the trace metals solution or by removing iron-containing precipitate from the growth medium, higher second-order rate coefficients were obtained. Copper also plays a role in CT transformation. Copper was toxic at neutral pH. By adjusting the medium pH to 8.2, soluble iron and copper levels decreased as a precipitate formed, and CT transformation rates increased. However, cultures grown at high pH without any added trace copper (1 microM) exhibited slower growth rates and greatly reduced rates of CT transformation, indicating that copper is required for CT transformation. The use of pH adjustment to decrease iron solubility, to avoid copper toxicity, and to provide a selective advantage for strain KC was evaluated by using soil slurries and groundwater containing high levels of iron. In samples adjusted to pH 8.2 and inoculated with strain KC, CT disappeared rapidly in the absence or presence of acetate or nitrate supplements. CT did not disappear in pH-adjusted controls that were not inoculated with strain KC. PMID:8357248

Phase transformations and equation of state of praseodymium metal to 103 GPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesnut, Gary N.; Vohra, Yogesh K.

2000-08-01

Pressure-induced structural phase transformations in a trivalent rare-earth metal praseodymium (Pr) were studied at room temperature in a diamond anvil cell to 103 GPa by energy dispersive x-ray diffraction using a synchrotron source. Our x-ray diffraction studies document the following crystal structure sequence: dhcp{yields}fcc{yields}distorted fcc(hR24 type){yields}monoclinic(C2/m){yields}{alpha}-uranium with increasing pressure. We measure a 16.7% volume collapse at the transition to the {alpha}-uranium phase at 20 GPa. The high-pressure {alpha}-uranium phase in Pr was found to be stable to the highest pressure of 103 GPa, which corresponds to a volume compression V/V{sub 0}=0.407. (c) 2000 The American Physical Society.

Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first-principles calculations.

PubMed

Andrés, Juan; Gracia, Lourdes; Gouveia, Amanda Fernandes; Ferrer, Mateus Meneghetti; Longo, Elson

2015-10-09

Morphology is a key property of materials. Owing to their precise structure and morphology, crystals and nanocrystals provide excellent model systems for joint experimental and theoretical investigations into surface-related properties. Faceted polyhedral crystals and nanocrystals expose well-defined crystallographic planes depending on the synthesis method, which allow for thoughtful investigations into structure-reactivity relationships under practical conditions. This feature article introduces recent work, based on the combined use of experimental findings and first-principles calculations, to provide deeper knowledge of the electronic, structural, and energetic properties controlling the morphology and the transformation mechanisms of different metals and metal oxides: Ag, anatase TiO2, BaZrO3, and α-Ag2WO4. According to the Wulff theorem, the equilibrium shapes of these systems are obtained from the values of their respective surface energies. These investigations are useful to gain further understanding of how to achieve morphological control of complex three-dimensional crystals by tuning the ratio of the surface energy values of the different facets. This strategy allows the prediction of possible morphologies for a crystal and/or nanocrystal by controlling the relative values of surface energies.

Oxidation-Mediated Fingering in Liquid Metals

NASA Astrophysics Data System (ADS)

Eaker, Collin B.; Hight, David C.; O'Regan, John D.; Dickey, Michael D.; Daniels, Karen E.

2017-10-01

We identify and characterize a new class of fingering instabilities in liquid metals; these instabilities are unexpected due to the large interfacial tension of metals. Electrochemical oxidation lowers the effective interfacial tension of a gallium-based liquid metal alloy to values approaching zero, thereby inducing drastic shape changes, including the formation of fractals. The measured fractal dimension (D =1.3 ±0.05 ) places the instability in a different universality class than other fingering instabilities. By characterizing changes in morphology and dynamics as a function of droplet volume and applied electric potential, we identify the three main forces involved in this process: interfacial tension, gravity, and oxidative stress. Importantly, we find that electrochemical oxidation can generate compressive interfacial forces that oppose the tensile forces at a liquid interface. The surface oxide layer ultimately provides a physical and electrochemical barrier that halts the instabilities at larger positive potentials. Controlling the competition between interfacial tension and oxidative (compressive) stresses at the interface is important for the development of reconfigurable electronic, electromagnetic, and optical devices that take advantage of the metallic properties of liquid metals.

SRC-like adaptor protein 2 (SLAP2) is a negative regulator of KIT-D816V-mediated oncogenic transformation.

PubMed

Rupar, Kaja; Moharram, Sausan A; Kazi, Julhash U; Rönnstrand, Lars

2018-04-23

KIT is a receptor tyrosine kinase (RTK) involved in several cellular processes such as regulation of proliferation, survival and differentiation of early hematopoietic cells, germ cells and melanocytes. Activation of KIT results in phosphorylation of tyrosine residues in the receptor, and recruitment of proteins that mediate downstream signaling and also modulate receptor signaling. Here we show that the SRC-like adaptor protein 2 (SLAP2) binds to wild-type KIT in a ligand-dependent manner and is furthermore found constitutively associated with the oncogenic mutant KIT-D816V. Peptide fishing analysis mapped pY568 and pY570 as potential SLAP2 association sites in KIT, which overlaps with the SRC binding sites in KIT. Expression of SLAP2 in cells expressing the transforming mutant KIT-D816V led to reduced cell viability and reduced colony formation. SLAP2 also partially blocked phosphorylation of several signal transduction molecules downstream of KIT such as AKT, ERK, p38 and STAT3. Finally, SLAP2 expression enhanced ubiquitination of KIT and its subsequent degradation. Taken together, our data demonstrate that SLAP2 negatively modulates KIT-D816V-mediated transformation by enhancing degradation of the receptor.

Efficient and genotype-independent Agrobacterium--mediated tomato transformation.

PubMed

Park, Sung Hun; Morris, Jay L; Park, Jung Eun; Hirschi, Kendal D; Smith, Roberta H

2003-10-01

An efficient method to transform five cultivars of tomato (Lycopersicon esculentum), Micro-Tom, Red Cherry, Rubion, Piedmont, and E6203 is reported. A comparison was made of leaf, cotyledon, and hypocotyl explants on 7 different regeneration media without Agrobacterium tumefaciens cocultivation and on 11 different media with cocultivation. Although all cultivars and explants formed callus and regenerated on the initial 7 media, cocultivation with A. tumefaciens significantly reduced the callus induction and regeneration. From these experiments, a transformation methodology using either hypocotyls or cotyledons cultured for one day on BA 1 mgL-1, NAA 0.1 mgL-1 and 3 days cocultivation with the Agrobacterium on this same medium followed by a transfer to a medium with zeatin 2 mgL-1 and IAA 0.1 mgL-1 for 4-6 weeks resulted in a greater than 20% transformation frequency for all five cultivars tested. In this transformation method, no feeder layers of tobacco, petunia or tomato suspension cultures were used, and the subculture media was minimal. Stable integration and transmission of the transgene in T1 generation plants were confirmed by Southern blot analysis. This procedure represents a simple, efficient and general means of transforming tomato.

Modeling of phase transformations of Ti6Al4 V during laser metal deposition

NASA Astrophysics Data System (ADS)

Suárez, A.; Tobar, M. J.; Yáñez, A.; Pérez, I.; Sampedro, J.; Amigó, V.; Candel, J. J.

The low density, excellent high temperature mechanical properties and good corrosion resistance of titanium and its alloys have led to a diversified range of successful applications. As a consequence, there is a demand of increasing the capabilities of processing such alloys. The laser cladding technique allows direct metal deposition with an excellent metallurgical bond and a pore free fine grained microstructure. A nonlinear transient thermo-metallurgical model was developed to study the technique with titanium alloys to get a better understanding of the thermal and metallurgical underlying aspects. The calculated temperatures and phase transformations are compared with experimental tests.

Transformational Leadership and Organizational Citizenship Behavior: A Meta-Analytic Test of Underlying Mechanisms.

PubMed

Nohe, Christoph; Hertel, Guido

2017-01-01

Based on social exchange theory, we examined and contrasted attitudinal mediators (affective organizational commitment, job satisfaction) and relational mediators (trust in leader, leader-member exchange; LMX) of the positive relationship between transformational leadership and organizational citizenship behavior (OCB). Hypotheses were tested using meta-analytic path models with correlations from published meta-analyses (761 samples with 227,419 individuals overall). When testing single-mediator models, results supported our expectations that each of the mediators explained the relationship between transformational leadership and OCB. When testing a multi-mediator model, LMX was the strongest mediator. When testing a model with a latent attitudinal mechanism and a latent relational mechanism, the relational mechanism was the stronger mediator of the relationship between transformational leadership and OCB. Our findings help to better understand the underlying mechanisms of the relationship between transformational leadership and OCB.

Transformational Leadership and Organizational Citizenship Behavior: A Meta-Analytic Test of Underlying Mechanisms

PubMed Central

Nohe, Christoph; Hertel, Guido

2017-01-01

Based on social exchange theory, we examined and contrasted attitudinal mediators (affective organizational commitment, job satisfaction) and relational mediators (trust in leader, leader-member exchange; LMX) of the positive relationship between transformational leadership and organizational citizenship behavior (OCB). Hypotheses were tested using meta-analytic path models with correlations from published meta-analyses (761 samples with 227,419 individuals overall). When testing single-mediator models, results supported our expectations that each of the mediators explained the relationship between transformational leadership and OCB. When testing a multi-mediator model, LMX was the strongest mediator. When testing a model with a latent attitudinal mechanism and a latent relational mechanism, the relational mechanism was the stronger mediator of the relationship between transformational leadership and OCB. Our findings help to better understand the underlying mechanisms of the relationship between transformational leadership and OCB. PMID:28848478

Cytoskeletal dynamics in interphase, mitosis and cytokinesis analysed through Agrobacterium-mediated transient transformation of tobacco BY-2 cells.

PubMed

Buschmann, H; Green, P; Sambade, A; Doonan, J H; Lloyd, C W

2011-04-01

Transient transformation with Agrobacterium is a widespread tool allowing rapid expression analyses in plants. However, the available methods generate expression in interphase and do not allow the routine analysis of dividing cells. Here, we present a transient transformation method (termed 'TAMBY2') to enable cell biological studies in interphase and cell division. Agrobacterium-mediated transient gene expression in tobacco BY-2 was analysed by Western blotting and quantitative fluorescence microscopy. Time-lapse microscopy of cytoskeletal markers was employed to monitor cell division. Double-labelling in interphase and mitosis enabled localization studies. We found that the transient transformation efficiency was highest when BY-2/Agrobacterium co-cultivation was performed on solid medium. Transformants produced in this way divided at high frequency. We demonstrated the utility of the method by defining the behaviour of a previously uncharacterized microtubule motor, KinG, throughout the cell cycle. Our analyses demonstrated that TAMBY2 provides a flexible tool for the transient transformation of BY-2 with Agrobacterium. Fluorescence double-labelling showed that KinG localizes to microtubules and to F-actin. In interphase, KinG accumulates on microtubule lagging ends, suggesting a minus-end-directed function in vivo. Time-lapse studies of cell division showed that GFP-KinG strongly labels preprophase band and phragmoplast, but not the metaphase spindle. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

Structure of the thermophilic l-Arabinose isomerase from Geobacillus kaustophilus reveals metal-mediated intersubunit interactions for activity and thermostability.

PubMed

Choi, Jin Myung; Lee, Yong-Jik; Cao, Thinh-Phat; Shin, Sun-Mi; Park, Min-Kyu; Lee, Han-Seung; di Luccio, Eric; Kim, Seong-Bo; Lee, Sang-Jae; Lee, Sang Jun; Lee, Sung Haeng; Lee, Dong-Woo

2016-04-15

Thermophilic l-arabinose isomerase (AI), which catalyzes the interconversion of l-arabinose and l-ribulose, can be used to produce d-tagatose, a sugar substitute, from d-galactose. Unlike mesophilic AIs, thermophilic AIs are highly dependent on divalent metal ions for their catalytic activity and thermostability at elevated temperatures. However, the molecular basis underlying the substrate preferences and metal requirements of multimeric AIs remains unclear. Here we report the first crystal structure of the apo and holo forms of thermophilic Geobacillus kaustophilus AI (GKAI) in hexamer form. The structures, including those of GKAI in complex with l-arabitol, and biochemical analyses revealed not only how the substrate-binding site of GKAI is formed through displacement of residues at the intersubunit interface when it is bound to Mn(2+), but also revealed the water-mediated H-bonding networks that contribute to the structural integrity of GKAI during catalysis. These observations suggest metal-mediated isomerization reactions brought about by intersubunit interactions at elevated temperatures are responsible for the distinct active site features that promote the substrate specificity and thermostability of thermophilic AIs. Copyright © 2016 Elsevier Inc. All rights reserved.

Biochemical transformation of coals

DOEpatents

Lin, Mow S.; Premuzic, Eugene T.

1999-03-23

A method of biochemically transforming macromolecular compounds found in solid carbonaceous materials, such as coal is provided. The preparation of new microorganisms, metabolically weaned through challenge growth processes to biochemically transform solid carbonaceous materials at extreme temperatures, pressures, pH, salt and toxic metal concentrations is also disclosed.

Synthesis and characterization of boric acid mediated metal-organic frameworks based on trimesic acid and terephthalic acid

NASA Astrophysics Data System (ADS)

Ozer, Demet; Köse, Dursun A.; Şahin, Onur; Oztas, Nursen Altuntas

2017-08-01

The new metal-organic framework materials based on boric acid reported herein. Sodium and boron containing metal-organic frameworks were synthesized by one-pot self-assembly reaction in the presence of trimesic acid and terephthalic acid in water/ethanol solution. Boric acid is a relatively cheap boron source and boric acid mediated metal-organic framework prepared mild conditions compared to the other boron source based metal-organic framework. The synthesized compounds were characterized by FT-IR, p-XRD, TGA/DTA, elemental analysis, 13C-MAS NMR, 11B-NMR and single crystal measurements. The molecular formulas of compounds were estimated as C18H33B2Na5O28 and C8H24B2Na2O17 according to the structural analysis. The obtained complexes were thermally stable. Surface properties of inorganic polymer complexes were investigated by BET analyses and hydrogen storage properties of compound were also calculated.

TRACE METAL TRANSFORMATION MECHANISMS DURING COAL COMBUSTION

EPA Science Inventory

The article reviews mechanisms governing the fate of trace metals during coal combustion and presents new theoretical results that interpret existing data. Emphasis is on predicting the size-segregated speciation of trace metals in pulverized-coal-fired power plant effluents. Thi...

Heat storage in alloy transformations

NASA Technical Reports Server (NTRS)

Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

1981-01-01

The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

Transformation of lettuce (Lactuca sativa) mediated by Agrobacterium tumefaciens.

PubMed

Michelmore, R; Marsh, E; Seely, S; Landry, B

1987-12-01

Lactuca sativa can be routinely transformed using Ti plasmids of Agrobacterium tumefaciens containing a chimeric kanamycin resistance gene (NOS.NPTII.NOS). Critical experimental variables were plant genotype, bacterial concentration, presence of a nurse culture and timing of transfers between tissue culture media. Transformation was confirmed by the ability to callus and root in the presence of kanamycin, nopaline production, and by hybridization in Southern blots. Transformation has been achieved with several Ti vectors. Several hundred transformed plants have been regenerated. Kanamycin resistance was inherited monogenically. Homozygotes can be selected by growing R2 seedlings on media containing G418.

Genetic Transformation of Switchgrass

NASA Astrophysics Data System (ADS)

Xi, Yajun; Ge, Yaxin; Wang, Zeng-Yu

Switchgrass (Panicum virgatum L.) is a highly productive warm-season C4 species that is being developed into a dedicated biofuel crop. This chapter describes a protocol that allows the generation of transgenic switchgrass plants by Agrobacterium tumefaciens-mediated transformation. Embryogenic calluses induced from caryopses or inflorescences were used as explants for inoculation with A. tumefaciens strain EHA105. Hygromycin phosphotransferase gene (hph) was used as the selectable marker and hygromycin was used as the selection agent. Calluses resistant to hygromycin were obtained after 5-6 weeks of selection. Soil-grown switchgrass plants were regenerated about 6 months after callus induction and Agrobacterium-mediated transformation.

Genetic transformation of switchgrass.

PubMed

Xi, Yajun; Ge, Yaxin; Wang, Zeng-Yu

2009-01-01

Switchgrass (Panicum virgatum L.) is a highly productive warm-season C4 species that is being developed into a dedicated biofuel crop. This chapter describes a protocol that allows the generation of transgenic switchgrass plants by Agrobacterium tumefaciens-mediated transformation. Embryogenic calluses induced from caryopses or inflorescences were used as explants for inoculation with A. tumefaciens strain EHA105. Hygromycin phosphotransferase gene (hph) was used as the selectable marker and hygromycin was used as the selection agent. Calluses resistant to hygromycin were obtained after 5-6 weeks of selection. Soil-grown switchgrass plants were regenerated about 6 months after callus induction and Agrobacterium-mediated transformation.

Influence of phase transformation on stress evolution during growth of metal thin films on silicon.

PubMed

Fillon, A; Abadias, G; Michel, A; Jaouen, C; Villechaise, P

2010-03-05

In situ stress measurements during two-dimensional growth of low mobility metal films on amorphous Si were used to demonstrate the impact of interface reactivity and phase transformation on stress evolution. Using Mo1-xSix films as examples, the results show that the tensile stress rise, which develops after the film has become crystalline, is correlated with an increase in lateral grain size. The origin of the tensile stress is attributed to the volume change resulting from the alloy crystallization, which occurs at a concentration-dependent critical thickness.

30 CFR 57.12085 - Transformer stations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Transformer stations. 57.12085 Section 57.12085 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Underground Only § 57.12085 Transformer stations. Transformer stations shall be enclosed to prevent persons...

30 CFR 57.12085 - Transformer stations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Transformer stations. 57.12085 Section 57.12085 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Underground Only § 57.12085 Transformer stations. Transformer stations shall be enclosed to prevent persons...

30 CFR 57.12085 - Transformer stations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Transformer stations. 57.12085 Section 57.12085 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Underground Only § 57.12085 Transformer stations. Transformer stations shall be enclosed to prevent persons...

30 CFR 57.12085 - Transformer stations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Transformer stations. 57.12085 Section 57.12085 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Underground Only § 57.12085 Transformer stations. Transformer stations shall be enclosed to prevent persons...

30 CFR 57.12085 - Transformer stations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Transformer stations. 57.12085 Section 57.12085 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Underground Only § 57.12085 Transformer stations. Transformer stations shall be enclosed to prevent persons...

Aegle marmelos Mediated Green Synthesis of Different Nanostructured Metal Hexacyanoferrates: Activity against Photodegradation of Harmful Organic Dyes

PubMed Central

Jassal, Vidhisha; Kaith, B. S.

2016-01-01

Prussian blue analogue potassium metal hexacyanoferrate (KMHCF) nanoparticles Fe4[Fe(CN)6]3 (FeHCF), K2Cu3[Fe(CN)6]2 (KCuHCF), K2Ni[Fe(CN)6]·3H2O (KNiHCF), and K2Co[Fe(CN)6] (KCoHCF) have been synthesized using plant based biosurfactant Aegle marmelos (Bael) and water as a green solvent. It must be emphasized here that no harmful reagent or solvent was used throughout the study. Plant extracts are easily biodegradable and therefore do not cause any harm to the environment. Hence, the proposed method of synthesis of various KMHCF nanoparticles followed a green path. The synthesized nanoparticles were characterized by powder X-ray diffraction (PXRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FT-IR). MHCF nanoparticles were used for the photocatalytic degradation of toxic dyes like Malachite Green (MG), Eriochrome Black T (EBT), Methyl Orange (MO), and Methylene Blue (MB). Under optimized reaction conditions, maximum photocatalytic degradation was achieved in case of KCuHCF nanoparticles mediated degradation process (MG: 96.06%, EBT: 83.03%, MB: 94.72%, and MO: 63.71%) followed by KNiHCF (MG: 95%, EBT: 80.32%, MB: 91.35%, and MO: 59.42%), KCoHCF (MG: 91.45%, EBT: 78.84%, MB: 89.28%, and MO: 58.20%). PMID:27034896

Metal-Mediated Modulation of Streptococcal Cysteine Protease Activity and Its Biological Implications

PubMed Central

Chella Krishnan, Karthickeyan; Mukundan, Santhosh; Landero Figueroa, Julio A.; Caruso, Joseph A.

2014-01-01

Streptococcal cysteine protease (SpeB), the major secreted protease produced by group A streptococcus (GAS), cleaves both host and bacterial proteins and contributes importantly to the pathogenesis of invasive GAS infections. Modulation of SpeB expression and/or its activity during invasive GAS infections has been shown to affect bacterial virulence and infection severity. Expression of SpeB is regulated by the GAS CovR-CovS two-component regulatory system, and we demonstrated that bacteria with mutations in the CovR-CovS two-component regulatory system are selected for during localized GAS infections and that these bacteria lack SpeB expression and exhibit a hypervirulent phenotype. Additionally, in a separate study, we showed that expression of SpeB can also be modulated by human transferrin- and/or lactoferrin-mediated iron chelation. Accordingly, the goal of this study was to investigate the possible roles of iron and other metals in modulating SpeB expression and/or activity in a manner that would potentiate bacterial virulence. Here, we report that the divalent metals zinc and copper inhibit SpeB activity at the posttranslational level. Utilizing online metal-binding site prediction servers, we identified two putative metal-binding sites in SpeB, one of which involves the catalytic-dyad residues 47Cys and 195His. Based on our findings, we propose that zinc and/or copper availability in the bacterial microenvironment can modulate the proteolytic activity of SpeB in a manner that preserves the integrity of several other virulence factors essential for bacterial survival and dissemination within the host and thereby may exacerbate the severity of invasive GAS infections. PMID:24799625

Biochemical transformation of coals

DOEpatents

Lin, M.S.; Premuzic, E.T.

1999-03-23

A method of biochemically transforming macromolecular compounds found in solid carbonaceous materials, such as coal is provided. The preparation of new microorganisms, metabolically weaned through challenge growth processes to biochemically transform solid carbonaceous materials at extreme temperatures, pressures, pH, salt and toxic metal concentrations is also disclosed. 7 figs.

Phase Transformations and Metallization of Magnesium Oxide at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

McWilliams, R. Stewart; Spaulding, Dylan K.; Eggert, Jon H.; Celliers, Peter M.; Hicks, Damien G.; Smith, Raymond F.; Collins, Gilbert W.; Jeanloz, Raymond

2012-12-01

Magnesium oxide (MgO) is representative of the rocky materials comprising the mantles of terrestrial planets, such that its properties at high temperatures and pressures reflect the nature of planetary interiors. Shock-compression experiments on MgO to pressures of 1.4 terapascals (TPa) reveal a sequence of two phase transformations: from B1 (sodium chloride) to B2 (cesium chloride) crystal structures above 0.36 TPa, and from electrically insulating solid to metallic liquid above 0.60 TPa. The transitions exhibit large latent heats that are likely to affect the structure and evolution of super-Earths. Together with data on other oxide liquids, we conclude that magmas deep inside terrestrial planets can be electrically conductive, enabling magnetic field-producing dynamo action within oxide-rich regions and blurring the distinction between planetary mantles and cores.

Studies of transformational leadership in consumer service: market orientation behavior and alternative roles for the mediators and moderators of change commitment.

PubMed

Yang, Yi-Feng

2013-12-01

The present paper evaluates the relation between transformational leadership and market orientation along with the mediating and moderating effects of change commitment for employees in customer centers in Taiwan. 327 questionnaires were returned by personnel at several customer centers in four different insurance companies. Inter-rater agreement was acceptable based on the multiple raters (i.e., the consumer-related employees from the division groups) of one individual (i.e., a manager)--indicating the aggregated measures were acceptable. The multi-source sample comprised data taken from the four division centers: phone services, customer representatives, financial specialists, and front-line salespeople. The relations were assessed using a multiple mediation procedure incorporating bootstrap techniques and PRODCLIN2 with structural equation modeling analysis. The results reflect a mediating role for change commitment.

Transformation of chlorinated paraffins to olefins during metal work and thermal exposure - Deconvolution of mass spectra and kinetics.

PubMed

Schinkel, Lena; Lehner, Sandro; Knobloch, Marco; Lienemann, Peter; Bogdal, Christian; McNeill, Kristopher; Heeb, Norbert V

2018-03-01

Chlorinated paraffins (CPs) are high production volume chemicals widely used as additives in metal working fluids. Thereby, CPs are exposed to hot metal surfaces which may induce degradation processes. We hypothesized that the elimination of hydrochloric acid would transform CPs into chlorinated olefins (COs). Mass spectrometry is widely used to detect CPs, mostly in the selected ion monitoring mode (SIM) evaluating 2-3 ions at mass resolutions R < 20'000. This approach is not suited to detected COs, because their mass spectra strongly overlap with CPs. We applied a mathematical deconvolution method based on full-scan MS data to separate interfered CP/CO spectra. Metal drilling indeed induced HCl-losses. CO proportions in exposed mixtures of chlorotridecanes increased. Thermal exposure of chlorotridecanes at 160, 180, 200 and 220 °C also induced dehydrohalogenation reactions and CO proportions also increased. Deconvolution of respective mass spectra is needed to study the CP transformation kinetics without bias from CO interferences. Apparent first-order rate constants (k app ) increased up to 0.17, 0.29 and 0.46 h -1 for penta-, hexa- and heptachloro-tridecanes exposed at 220 °C. Respective half-life times (τ 1/2 ) decreased from 4.0 to 2.4 and 1.5 h. Thus, higher chlorinated paraffins degrade faster than lower chlorinated ones. In conclusion, exposure of CPs during metal drilling and thermal treatment induced HCl losses and CO formation. It is expected that CPs and COs are co-released from such processes. Full-scan mass spectra and subsequent deconvolution of interfered signals is a promising approach to tackle the CP/CO problem, in case of insufficient mass resolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cotton transformation via pollen tube pathway.

PubMed

Wang, Min; Zhang, Baohong; Wang, Qinglian

2013-01-01

Although many gene transfer methods have been employed for successfully obtaining transgenic cotton, the major constraint in cotton improvement is the limitation of genotype because the majority of transgenic methods require plant regeneration from a single transformed cell which is limited by cotton tissue culture. Comparing with other plant species, it is difficult to induce plant regeneration from cotton; currently, only a limited number of cotton cultivars can be cultured for obtaining regenerated plants. Thus, development of a simple and genotype-independent genetic transformation method is particularly important for cotton community. In this chapter, we present a simple, cost-efficient, and genotype-independent cotton transformation method-pollen tube pathway-mediated transformation. This method uses pollen tube pathway to deliver transgene into cotton embryo sacs and then insert foreign genes into cotton genome. There are three major steps for pollen tube pathway-mediated genetic transformation, which include injection of -foreign genes into pollen tube, integration of foreign genes into plant genome, and selection of transgenic plants.

Agrobacterium-mediated transformation of protocorm-like bodies in Cymbidium.

PubMed

Chin, Dong Poh; Mishiba, Kei-ichiro; Mii, Masahiro

2007-06-01

Genetically transformed plants of Cymbidium were regenerated after cocultivating protocorm-like bodies (PLB) with Agrobacterium tumefaciens strain EHA101 (pIG121Hm) that harbored genes for beta-glucuronidase (gus), hygromycin phosphotransferase (hpt) and neomycin phosphotransferase II (nptII). PLB of three genotypes maintained in liquid new Dogashima medium (NDM), were subjected to transformation experiments. The PLB inoculated with Agrobacterium produced secondary PLB, 4 weeks after transfer onto 2.5 g L(-1) gellan gum-solidified NDM containing 10 g L(-1) sucrose, 20 mg L(-1) hygromycin and 40 mg L(-1) meropenem. Transformation efficiency was affected by genotype and the presence of acetosyringone during cocultivation. The highest transformation efficiency was obtained when PLB from the genotype L4 were infected and cocultivated with Agrobacterium on medium containing 100 muM acetosyringone. Transformation of the hygromycin-resistant plantlets regenerated from different sites of inoculated PLB was confirmed by histochemical GUS assay, PCR analysis and Southern blot hybridization.

Protoplast isolation, transient transformation of leaf mesophyll protoplasts and improved Agrobacterium-mediated leaf disc infiltration of Phaseolus vulgaris: tools for rapid gene expression analysis.

PubMed

Nanjareddy, Kalpana; Arthikala, Manoj-Kumar; Blanco, Lourdes; Arellano, Elizabeth S; Lara, Miguel

2016-06-24

Phaseolus vulgaris is one of the most extensively studied model legumes in the world. The P. vulgaris genome sequence is available; therefore, the need for an efficient and rapid transformation system is more imperative than ever. The functional characterization of P. vulgaris genes is impeded chiefly due to the non-amenable nature of Phaseolus sp. to stable genetic transformation. Transient transformation systems are convenient and versatile alternatives for rapid gene functional characterization studies. Hence, the present work focuses on standardizing methodologies for protoplast isolation from multiple tissues and transient transformation protocols for rapid gene expression analysis in the recalcitrant grain legume P. vulgaris. Herein, we provide methodologies for the high-throughput isolation of leaf mesophyll-, flower petal-, hypocotyl-, root- and nodule-derived protoplasts from P. vulgaris. The highly efficient polyethylene glycol-mannitol magnesium (PEG-MMG)-mediated transformation of leaf mesophyll protoplasts was optimized using a GUS reporter gene. We used the P. vulgaris SNF1-related protein kinase 1 (PvSnRK1) gene as proof of concept to demonstrate rapid gene functional analysis. An RT-qPCR analysis of protoplasts that had been transformed with PvSnRK1-RNAi and PvSnRK1-OE vectors showed the significant downregulation and ectopic constitutive expression (overexpression), respectively, of the PvSnRK1 transcript. We also demonstrated an improved transient transformation approach, sonication-assisted Agrobacterium-mediated transformation (SAAT), for the leaf disc infiltration of P. vulgaris. Interestingly, this method resulted in a 90 % transformation efficiency and transformed 60-85 % of the cells in a given area of the leaf surface. The constitutive expression of YFP further confirmed the amenability of the system to gene functional characterization studies. We present simple and efficient methodologies for protoplast isolation from multiple P

Optimization of in vitro regeneration and Agrobacterium tumefaciens-mediated transformation with heat-resistant cDNA in Brassica oleracea subsp. italica cv. Green Marvel.

PubMed

Ravanfar, Seyed Ali; Aziz, Maheran Abdul; Saud, Halimi Mohd; Abdullah, Janna Ong

2015-11-01

An efficient system for shoot regeneration and Agrobacterium tumefaciens-mediated transformation of Brassica oleracea cv. Green Marvel cultivar is described. This study focuses on developing shoot regeneration from hypocotyl explants of broccoli cv. Green Marvel using thidiazuron (TDZ), zeatin, and kinetin, the optimization of factors affecting Agrobacterium-mediated transformation of the hypocotyl explants with heat-resistant cDNA, followed by the confirmation of transgenicity of the regenerants. High shoot regeneration was observed in 0.05-0.1 mg dm(-3) TDZ. TDZ at 0.1 mg dm(-3) produced among the highest percentage of shoot regeneration (96.67 %) and mean number of shoot formation (6.17). The highest percentage (13.33 %) and mean number (0.17) of putative transformant production were on hypocotyl explants subjected to preculture on shoot regeneration medium (SRM) with 200 µM acetosyringone. On optimization of bacterial density and inoculation time, the highest percentage and mean number of putative transformant production were on hypocotyl explants inoculated with a bacterial dilution of 1:5 for 30 min. Polymerase chain reaction (PCR) assay indicated a transformation efficiency of 8.33 %. The luciferase assay showed stable integration of the Arabidopsis thaliana HSP101 (AtHSP101) cDNA in the transgenic broccoli regenerants. Three out of five transgenic lines confirmed through PCR showed positive hybridization bands of the AtHSP101 cDNA through Southern blot analysis. The presence of AtHSP101 transcripts in the three transgenic broccoli lines indicated by reverse transcription-PCR (RT-PCR) confirmed the expression of the gene. In conclusion, an improved regeneration system has been established from hypocotyl explants of broccoli followed by successful transformation with AtHSP101 for resistance to high temperature.

High pressure phase-transformation induced texture evolution and strengthening in zirconium metal: Experiment and modeling

DOE PAGES

Yu, Xiaohui; Zhang, Ruifeng; Weldon, David; ...

2015-07-28

We studied the phase-transition induced texture changes and strengthening mechanism for zirconium metal under quasi-hydrostatic compression and uni-axial deformation under confined high pressure using the deformation-DIA (D-DIA) apparatus. It is shown that the experimentally obtained texture for ω-phase Zr can be qualitatively described by combining a subset of orientation variants previously proposed in two different models. The determined flow stress for the high-pressure ω-phase is 0.5–1.2 GPa, more than three times higher than that of the α-phase. Using first-principles calculations, we investigated the mechanical and electronic properties of the two Zr polymorphs. We find that the observed strengthening can bemore » attributed to the relatively strong directional bonding in the ω phase, which significantly increases its shear plastic resistance over the α-phase Zr. The present findings provide an alternate route for Zr metal strengthening by high-pressure phase transformation.« less

Agrobacterium tumefaciens-mediated transformation of Narcissus tazzeta var. chinensis.

PubMed

Lu, Gang; Zou, Qingcheng; Guo, Deping; Zhuang, Xiaoying; Yu, Xiaolin; Xiang, Xun; Cao, Jiashu

2007-09-01

Phytoene synthase (PSY), as a key regulatory enzyme for carotene biosynthesis, plays an important role in regulating color formation in many species. In the present study, a protocol was developed for the transformation of Narcissus tazzeta var chinensis using Agrobacterium tumefaciens strain LBA4404 harboring a binary vector pCAMBIA1301 plasmid which contained an antisense phytoene synthase gene, a reporter beta-glucuronidase gene and a selectable marker hygromycin phosphotransferase gene. Effects of some factors on efficiency of transformation and regeneration were examined. Preculture of the explants for 6 days before inoculation enhanced the transient GUS expression. The addition of acetosyringone (AS) at 100 micromol l(-1) for inoculation and a period of 3 days co-cultivation yielded efficient transient GUS expression. Transformants were obtained through selection on MS medium containing 5 mg l(-1) 6-benzylaminopurine (BA), 0.1 mg l(-1)alpha-naphthalene acetic acid (NAA) and 40 mg l(-1) hygromycin. The transformation frequency was 1.24% based on PCR analysis of gus gene. One or two copies of transgene were demonstrated in different transformations by Southern blotting analyses. Northern blotting results confirmed that the transcription of the endogenous psy gene in transgenic plants was inhibited or silenced. The method reported here provides new opportunities for improvement of quality traits of Narcissus tazzeta via genetic transformation.

Mediation of wound-related Rous sarcoma virus tumorigenesis by TFG (transforming growth factor)-. beta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sieweke, M.H.; Bissell, M.J.; Thompson, N.L.

1990-06-29

In Rous sarcoma virus (RSV)-infected chickens, wounding leads to tumor formation with nearly 100% frequency in tissues that would otherwise remain tumor-free. Identifying molecular mediators of this phenomenon should yield important clues to the mechanisms involved in RSV tumorigenesis. Immunohistochemical staining showed that TGF-{beta} is present locally shortly after wounding, but not in unwounded controls. In addition, subcutaneous administration of recombinant transforming growth factor {beta}1 (TGF-{beta}1) could substitute completely for wounding in tumor induction. A treatment protocol of four doses of 800 nanograms of TGF-{beta} resulted in v-src-expressing tumors with 100% frequency; four doses of only 10 nanograms still ledmore » to tumor formation in 80% of the animals. This effect was specific, as other growth factors with suggested roles in would healing did not elicit the same response. Epidermal growth factor (EGF) or TGF-{alpha} had no effect, and platelet-derived growth factor (PDGF) or insulin-like growth factor-1 (IGF-1) yielded only occasional tumors after longer latency. TGF-{beta} release during the would-healing response may thus be a critical event that creates a conducive environment for RSV tumorigenesis and may act as a cofactor for transformation in this system. 31 refs., 3 figs., 2 tabs.« less

VIP1 and Its Homologs Are Not Required for Agrobacterium-Mediated Transformation, but Play a Role in Botrytis and Salt Stress Responses

PubMed Central

Lapham, Rachelle; Lee, Lan-Ying; Tsugama, Daisuke; Lee, Sanghun; Mengiste, Tesfaye; Gelvin, Stanton B.

2018-01-01

The bZIP transcription factor VIP1 interacts with the Agrobacterium virulence protein VirE2, but the role of VIP1 in Agrobacterium-mediated transformation remains controversial. Previously tested vip1-1 mutant plants produce a truncated protein containing the crucial bZIP DNA-binding domain. We generated the CRISPR/Cas mutant vip1-2 that lacks this domain. The transformation susceptibility of vip1-2 and wild-type plants is similar. Because of potential functional redundancy among VIP1 homologs, we tested transgenic lines expressing VIP1 fused to a SRDX repression domain. All VIP1-SRDX transgenic lines showed wild-type levels of transformation, indicating that neither VIP1 nor its homologs are required for Agrobacterium-mediated transformation. Because VIP1 is involved in innate immune response signaling, we tested the susceptibility of vip1 mutant and VIP1-SRDX plants to Pseudomonas syringae and Botrytis cinerea. vip1 mutant and VIP1-SRDX plants show increased susceptibility to B. cinerea but not to P. syringae infection, suggesting a role for VIP1 in B. cinerea, but not in P. syringae, defense signaling. B. cinerea susceptibility is dependent on abscisic acid (ABA) which is also important for abiotic stress responses. The germination of vip1 mutant and VIP1-SRDX seeds is sensitive to exogenous ABA, suggesting a role for VIP1 in response to ABA. vip1 mutant and VIP1-SRDX plants show increased tolerance to growth in salt, indicating a role for VIP1 in response to salt stress. PMID:29946325

30 CFR 57.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Locking transformer enclosures. 57.12068 Section 57.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface Only § 57.12068 Locking transformer enclosures. Transformer enclosures shall be kept...

30 CFR 57.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Locking transformer enclosures. 57.12068 Section 57.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface Only § 57.12068 Locking transformer enclosures. Transformer enclosures shall be kept...

30 CFR 57.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Locking transformer enclosures. 57.12068 Section 57.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface Only § 57.12068 Locking transformer enclosures. Transformer enclosures shall be kept...

30 CFR 57.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Locking transformer enclosures. 57.12068 Section 57.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface Only § 57.12068 Locking transformer enclosures. Transformer enclosures shall be kept...

30 CFR 56.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

30 CFR 56.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

30 CFR 56.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

30 CFR 56.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

30 CFR 56.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Locking transformer enclosures. 56.12068 Section 56.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... § 56.12068 Locking transformer enclosures. Transformer enclosures shall be kept locked against...

30 CFR 57.12068 - Locking transformer enclosures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Locking transformer enclosures. 57.12068 Section 57.12068 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface Only § 57.12068 Locking transformer enclosures. Transformer enclosures shall be kept...

Development of an Efficient Agrobacterium-Mediated Transformation System and Production of Herbicide-Resistant Transgenic Plants in Garlic (Allium sativum L.)

PubMed Central

Ahn, Yul-Kyun; Yoon, Moo-Kyoung; Jeon, Jong-Seong

2013-01-01

The genetic improvement of garlic plants (Allium sativum L.) with agronomical beneficial traits is rarely achieved due to the lack of an applicable transformation system. Here, we developed an efficient Agrobacterium-mediated transformation procedure with Danyang, an elite Korean garlic cultivar. Examination of sGFP (synthetic green fluorescence protein) expression revealed that treatment with 2-(N-morpholino) ethanesulfonic acid (MES), L-cysteine and/or dithiothreitol (DTT) gives the highest efficiency in transient gene transfer during Agrobacterium co-cultivation with calli derived from the roots of in vitro plantlets. To increase stable transformation efficiency, a two-step selection was employed on the basis of hygromycin resistance and sGFP expression. Of the hygromycin-resistant calli initially produced, only sGFP-expressing calli were subcultured for selection of transgenic calli. Transgenic plantlets produced from these calli were grown to maturity. The transformation efficiency increased up to 10.6% via our optimized procedure. DNA and RNA gel-blot analysis indicated that transgenic garlic plants stably integrated and expressed the phosphinothricin acetyltransferase (PAT) gene. A herbicide spraying assay demonstrated that transgenic plants of garlic conferred herbicide resistance, whilst non-transgenic plants and weeds died. These results indicate that our transformation system can be efficiently utilized to produce transgenic garlic plants with agronomic benefits. PMID:23832764

Development of an efficient Agrobacterium-mediated transformation system and production of herbicide-resistant transgenic plants in garlic (Allium sativum L.).

PubMed

Ahn, Yul-Kyun; Yoon, Moo-Kyoung; Jeon, Jong-Seong

2013-08-01

The genetic improvement of garlic plants (Allium sativum L.) with agronomical beneficial traits is rarely achieved due to the lack of an applicable transformation system. Here, we developed an efficient Agrobacterium-mediated transformation procedure with Danyang, an elite Korean garlic cultivar. Examination of sGFP (synthetic green fluorescence protein) expression revealed that treatment with 2-(N-morpholino) ethanesulfonic acid (MES), L-cysteine and/or dithiothreitol (DTT) gives the highest efficiency in transient gene transfer during Agrobacterium co-cultivation with calli derived from the roots of in vitro plantlets. To increase stable transformation efficiency, a two-step selection was employed on the basis of hygromycin resistance and sGFP expression. Of the hygromycin-resistant calli initially produced, only sGFP-expressing calli were subcultured for selection of transgenic calli. Transgenic plantlets produced from these calli were grown to maturity. The transformation efficiency increased up to 10.6% via our optimized procedure. DNA and RNA gel-blot analysis indicated that transgenic garlic plants stably integrated and expressed the phosphinothricin acetyltransferase (PAT) gene. A herbicide spraying assay demonstrated that transgenic plants of garlic conferred herbicide resistance, whilst nontransgenic plants and weeds died. These results indicate that our transformation system can be efficiently utilized to produce transgenic garlic plants with agronomic benefits.

Ionothermal synthesis and structural transformation targeted by ion exchange in metal-1,3,5-benzenetricarboxylate compounds

NASA Astrophysics Data System (ADS)

Xu, Qing-Qing; Liu, Bing; Xu, Ling; Jiao, Huan

2017-03-01

Ionothermal reactions of 1,3,5-benzenetricarboxylate acid (H3BTC) and Ni(NO3)2, Co(NO3)2 and Cu(NO3)2 gave two discrete 32-membered ring-like allomers, [M2(HBTC)2(NH2CONH2)2(H2O)4]·3H2O (M=Ni(1), Co(2)) and one layered [Cu2(BTC)Cl(H2O)4] (3). The weak interactions in 1 can be deconstructed to some degree in ion exchange by exploring the factors of divalent and trivalent metal species, metal concentration and soaking time, which are demonstrated by PXRD and N2 absorption. Cu2+ has the highest N2 adsorbance when soaking with 1, and 1 can keep structure stable when Cu2+ below 0.16 mol L-1 and the soaking time within 24d. As Cu2+ beyond 0.16 mol L-1 and the soaking time beyond 24d, the structure of compound 1 starts to transform with the crystal morphology from clear pale green to opaque blue. Ionothermal reactions of compound 1 with different Cu2+ amounts obtained Ni2+-Cu2+ hetero complexes, whose PXRD patterns are similar to that of 3 and EDS indicates Cu2+% increases with Cu2+ additions and close to 100% as Cu2+ being 1.6 mmol. It suggests that 3 is a controlled product and Cu2+ can transform discrete compound 1 into 2D compound 3.

Regeneration of hyaline cartilage by cell-mediated gene therapy using transforming growth factor beta 1-producing fibroblasts.

PubMed

Lee, K H; Song, S U; Hwang, T S; Yi, Y; Oh, I S; Lee, J Y; Choi, K B; Choi, M S; Kim, S J

2001-09-20

Transforming growth factor beta (TGF-beta) has been considered as a candidate for gene therapy of orthopedic diseases. The possible application of cell-mediated TGF-beta gene therapy as a new treatment regimen for degenerative arthritis was investigated. In this study, fibroblasts expressing active TGF-beta 1 were injected into the knee joints of rabbits with artificially made cartilage defects to evaluate the feasibility of this therapy for orthopedic diseases. Two to 3 weeks after the injection there was evidence of cartilage regeneration, and at 4 to 6 weeks the cartilage defect was completely filled with newly grown hyaline cartilage. Histological analyses of the regenerated cartilage suggested that it was well integrated with the adjacent normal cartilage at the sides of the defect and that the newly formed tissue was indeed hyaline cartilage. Our findings suggest that cell-mediated TGF-beta 1 gene therapy may be a novel treatment for orthopedic diseases in which hyaline cartilage damage has occurred.

Engineering island-chain silicon nanowires via a droplet mediated Plateau-Rayleigh transformation

PubMed Central

Xue, Zhaoguo; Xu, Mingkun; Zhao, Yaolong; Wang, Jimmy; Jiang, Xiaofan; Yu, Linwei; Wang, Junzhuan; Xu, Jun; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

2016-01-01

The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities. We here exploit a nanoscale locomotion of metal droplets to demonstrate a large and readily controllable morphology engineering of crystalline SiNWs, from straight ones into continuous or discrete island-chains, at temperature <350 °C. This has been accomplished via a tin (Sn) droplet mediated in-plane growth where amorphous Si thin film is consumed as precursor to produce crystalline SiNWs. Thanks to a significant interface-stretching effect, a periodic Plateau-Rayleigh instability oscillation can be stimulated in the liquid Sn droplet, and the temporal oscillation of the Sn droplets is translated faithfully, via the deformable liquid/solid deposition interface, into regular spatial modulation upon the SiNWs. Combined with a unique self-alignment and positioning capability, this new strategy could enable a rational design and single-run fabrication of a wide variety of nanowire-based optoelectronic devices. PMID:27682161

Decomposition of ferrite in commercial superduplex stainless steel weld metals; microstructural transformations above 700 °C

NASA Astrophysics Data System (ADS)

Gregori, A.; Nilsson, J.-O.

2002-04-01

The microstructural stability at temperatures above 700 °C of weld metal of type 29Cr-8Ni-2Mo-0.39N and weld metal of type 25Cr-10Ni-4Mo-0.28N has been compared. Multipass welding was employed using the gas tungsten arc welding technique with a shielding gas of Ar+2 pct N2. The quantitative assessment of the intermetallic phase was performed using automatic image analysis in the light optical microscope (LOM). Detailed microanalysis was also performed using scanning and transmission electron microscopy. A computer program developed by the authors was used to calculate a continuous cooling-temperature (CCT) diagram on the basis of the experimentally determined time-temperature-transformation (TTT) diagram. Thermodynamic calculations for estimating phase stabilities and for interpreting experimental observations were performed. It was found that weld metal of type 29Cr-8Ni-2Mo-0.39N was microstructurally more stable than weld metal of type 25Cr-10Ni-4Mo-0.28N. A lower molybdenum concentration and a higher nitrogen concentration in the former alloy could explain the higher stability with respect to the intermetallic phase. The higher nitrogen concentration also provides a rationale for the higher stability against the formation of secondary austenite in weld metal of type 29Cr-8Ni-2Mo-0.39N. This effect, which is associated with a lower thermodynamic driving force for precipitation of secondary austenite during multipass welding, can be explained by nitrogen-enhanced primary austenite formation.

Metal-centred azaphosphatriptycene gear with a photo- and thermally driven mechanical switching function based on coordination isomerism.

PubMed

Ube, Hitoshi; Yasuda, Yoshihiro; Sato, Hiroyasu; Shionoya, Mitsuhiko

2017-02-08

Metal ions can serve as a centre of molecular motions due to their coordination geometry, reversible bonding nature and external stimuli responsiveness. Such essential features of metal ions have been utilized for metal-mediated molecular machines with the ability to motion switch via metallation/demetallation or coordination number variation at the metal centre; however, motion switching based on the change in coordination geometry remain largely unexplored. Herein, we report a Pt II -centred molecular gear that demonstrates control of rotor engagement and disengagement based on photo- and thermally driven cis-trans isomerization at the Pt II centre. This molecular rotary motion transmitter has been constructed from two coordinating azaphosphatriptycene rotators and one Pt II ion as a stator. Isomerization between an engaged cis-form and a disengaged trans-form is reversibly driven by ultraviolet irradiation and heating. Such a photo- and thermally triggered motional interconversion between engaged/disengaged states on a metal ion would provide a selector switch for more complex interlocking systems.

Sulfur-Mediated Electron Shuttling Sustains Microbial Long-Distance Extracellular Electron Transfer with the Aid of Metallic Iron Sulfides.

PubMed

Kondo, Katsuhito; Okamoto, Akihiro; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-07-07

In addition to serving as an energy source for microbial growth, iron sulfides are proposed to act as naturally occurring electrical wires that mediate long-distance extracellular electron transfer (EET) and bridge spatially discrete redox environments. These hypothetical EET reactions stand on the abilities of microbes to use the interfacial electrochemistry of metallic/semiconductive iron sulfides to maintain metabolisms; however, the mechanisms of these phenomena remain unexplored. To obtain insight into EET to iron sulfides, we monitored EET at the interface between Shewanella oneidensis MR-1 cells and biomineralized iron sulfides in an electrochemical cell. Respiratory current steeply increased with the concomitant formation of poorly crystalline mackinawite (FeS) minerals, indicating that S. oneidensis has the ability to exploit extracellularly formed metallic FeS for long-distance EET. Deletion of major proteins of the metal-reduction (Mtr) pathway (OmcA, MtrC, CymA, and PilD) caused only subtle effects on the EET efficiency, a finding that sharply contrasts the majority of studies that report that the Mtr pathway is indispensable for the reduction of metal oxides and electrodes. The gene expression analyses of polysulfide and thiosulfate reductase suggest the existence of a sulfur-mediated electron-shuttling mechanism by which HS(-) ions and water-soluble polysulfides (HS(n)(-), where n ≥ 2) generated in the periplasmic space deliver electrons from cellular metabolic processes to cell surface-associated FeS. The finding of this Mtr-independent pathway indicates that polysulfide reductases complement the function of outer-membrane cytochromes in EET reactions and, thus, significantly expand the number of microbial species potentially capable of long-distance EET in sulfur-rich anoxic environments.

Agrobacterium tumefasciens-mediated transformation of the aquatic fungus Blastocladiella emersonii.

PubMed

Vieira, André L G; Camilo, César M

2011-08-01

Agrobacterium tumefaciens is widely used for plant DNA transformation and more recently, has also been used to transform yeast, filamentous fungi and even human cells. Using this technique, we developed the first transformation protocol for the saprobic aquatic fungus Blastocladiella emersonii, a Blastocladiomycete localized at the base of fungal phylogenetic tree, which has been shown as a promising and interesting model of study of cellular function and differentiation. We constructed binary T-DNA vectors containing hygromycin phosphotransferase (hph) or enhanced green fluorescent protein (egfp) genes, under the control of Aspergillus nidulans trpC promoter and terminator sequences. 24 h of co-cultivation in induction medium (IM) agar plates, followed by transfer to PYG-agar plates containing cefotaxim to kill Agrobacterium tumefsciens and hygromycin to select transformants, resulted in growth and sporulation of resistant transformants. Genomic DNA from the pool o resistant zoospores were shown to contain T-DNA insertion as evidenced by PCR amplification of hph gene. Using a similar protocol we could also evidence the expression of enhanced green fluorescent protein (EGFP) in zoospores derived from transformed cells. This protocol can also open new perspectives for other non-transformable closely related fungi, like the Chytridiomycete class. Copyright © 2011 Elsevier Inc. All rights reserved.

Early events in Agrobacterium-mediated genetic transformation of citrus explants.

PubMed

Peña, Leandro; Pérez, Rosa M; Cervera, Magdalena; Juárez, José A; Navarro, Luis

2004-07-01

Genetic transformation of plants relies on two independent but concurrent processes: integration of foreign DNA into plant cells and regeneration of whole plants from these transformed cells. Cell competence for regeneration and for transformation does not always fall into the same cell type/developmental stage, and this is one of the main causes of the so-called recalcitrance for transformation of certain plant species. In this study, a detailed examination of the first steps of morphogenesis from citrus explants after co-cultivation with Agrobacterium tumefaciens was performed, and an investigation into which cells and tissues are competent for regeneration and transformation was carried out. Moreover, the role of phytohormones in the co-cultivation medium as possible enhancers of gene transfer was also studied. A highly responsive citrus genotype and well-established culture conditions were used to perform a histological analysis of morphogenesis and cell competence for transformation after co-cultivation of citrus epicotyl segments with A. tumefaciens. In addition, the role of phytohormones as transformation enhancers was investigated by flow cytometry. It is demonstrated that cells competent for transformation are located in the newly formed callus growing from the cambial ring. Conditions conducive to further development of this callus, such as treatment of explants in a medium rich in auxins, resulted in a more pronounced formation of cambial callus and a slower shoot regeneration process, both in Agrobacterium-inoculated and non-inoculated explants. Furthermore, co- cultivation in a medium rich in auxins caused a significant increase in the rate of actively dividing cells in S-phase, the stage in which cells are more prone to integrate foreign DNA. Use of proper co-cultivation medium and conditions led to a higher number of stably transformed cells and to an increase in the final number of regenerated transgenic plants.

Improved Agrobacterium-mediated transformation and high efficiency of root formation from hypocotyl meristem of spring Brassica napus 'Precocity' cultivar.

PubMed

Liu, X X; Lang, S R; Su, L Q; Liu, X; Wang, X F

2015-12-14

Rape seed (Brassica napus L.) is one of the most important oil seed crops in the world. Genetic manipulation of rapeseed requires a suitable tissue culture system and an efficient method for plant regeneration, as well as an efficient transformation procedure. However, development of transgenic B. napus has been problematic, and current studies are limited to cultivated varieties. In this study, we report a protocol for regeneration of transgenic rape after Agrobacterium-mediated transformation of hypocotyls from the spring B. napus 'Precocity' cultivar. We analyzed the effects of plant growth regulators in the medium on regeneration. Additionally, factors affecting the transformation efficiency, including seedling age, Agrobacterium concentration, infection time, and co-cultivation time, were assessed by monitoring GUS expression. Results from these experiments revealed that transformation was optimized when the meristematic parts of the hypocotyls were taken from 8 day-old seedlings, cultured on Murashinge and Skoog basal media containing 0.1 mg/L 1-naphthaleneacetic acid and 2.5 mg/L 6-benzylaminopurine, and incubated in Agrobacterium suspension (OD600 = 0.5) for 3 to 5 min, followed by 2 days of co-cultivation. Integration of T-DNA into the plant genome was confirmed by polymerase chain reaction (PCR), b-glucuronidase histochemical staining, and quantitative real-time PCR. The protocols developed for regeneration, transformation, and rooting described in this study could help to accelerate the development of transgenic spring rape varieties with novel features.

Cell transformation by human adenoviruses.

PubMed

Endter, C; Dobner, T

2004-01-01

The last 40 years of molecular biological investigations into human adenoviruses have contributed enormously to our understanding of the basic principles of normal and malignant cell growth. Much of this knowledge stems from analyses of their productive infection cycle in permissive host cells. Also, initial observations concerning the carcinogenic potential of human adenoviruses subsequently revealed decisive insights into the molecular mechanisms of the origins of cancer, and established adenoviruses as a model system for explaining virus-mediated transformation processes. Today it is well established that cell transformation by human adenoviruses is a multistep process involving several gene products encoded in early transcription units 1A (E1A) and 1B (E1B). Moreover, a large body of evidence now indicates that alternative or additional mechanisms are engaged in adenovirus-mediated oncogenic transformation involving gene products encoded in early region 4 (E4) as well as epigenetic changes resulting from viral DNA integration. In particular, detailed studies on the tumorigenic potential of subgroup D adenovirus type 9 (Ad9) E4 have now revealed a new pathway that points to a novel, general mechanism of virus-mediated oncogenesis. In this chapter, we summarize the current state of knowledge about the oncogenes and oncogene products of human adenoviruses, focusing particularly on recent findings concerning the transforming and oncogenic properties of viral proteins encoded in the E1B and E4 transcription units.

Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.

2008-02-15

Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP datamore » showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.« less

Determination of the transforming activities of adenovirus oncogenes.

PubMed

Nevels, Michael; Dobner, Thomas

2007-01-01

The last 50 yr of molecular biological investigations into human adenoviruses (Ads) have contributed enormously to our understanding of the basic principles of normal and malignant cell growth. Much of this knowledge stems from analyses of the Ad productive infection cycle in permissive host cells. Also, initial observations concerning the transforming potential of human Ads subsequently revealed decisive insights into the molecular mechanisms of the origins of cancer and established Ads as a model system for explaining virus-mediated transformation processes. Today it is well established that cell transformation by human Ads is a multistep process involving several gene products encoded in early transcription units 1A (E1A) and 1B (E1B). Moreover, a large body of evidence now indicates that alternative or additional mechanisms are engaged in Ad-mediated oncogenic transformation involving gene products encoded in early region 4 (E4) as well as epigenetic changes resulting from viral DNA integration. In particular, studies on the transforming potential of several E4 gene products have now revealed new pathways that point to novel general mechanisms of virus-mediated oncogenesis. In this chapter we describe in vitro and in vivo assays to determine the transforming and oncogenic activities of the E1A, E1B, and E4 oncoproteins in primary baby rat kidney cells and athymic nude mice.

Determination of the transforming activities of adenovirus oncogenes.

PubMed

Speiseder, Thomas; Nevels, Michael; Dobner, Thomas

2014-01-01

The last 50 years of molecular biological investigations into human adenoviruses (Ads) have contributed enormously to our understanding of the basic principles of normal and malignant cell growth. Much of this knowledge stems from analyses of the Ad productive infection cycle in permissive host cells. Also, initial observations concerning the transforming potential of human Ads subsequently revealed decisive insights into the molecular mechanisms of the origins of cancer and established Ads as a model system for explaining virus-mediated transformation processes. Today it is well established that cell transformation by human Ads is a multistep process involving several gene products encoded in early transcription units 1A (E1A) and 1B (E1B). Moreover, a large body of evidence now indicates that alternative or additional mechanisms are engaged in Ad-mediated oncogenic transformation involving gene products encoded in early region 4 (E4) as well as epigenetic changes resulting from viral DNA integration. In particular, studies on the transforming potential of several E4 gene products have now revealed new pathways that point to novel general mechanisms of virus-mediated oncogenesis. In this chapter we describe in vitro and in vivo assays to determine the transforming and oncogenic activities of the E1A, E1B, and E4 oncoproteins in primary baby rat kidney cells, human amniotic fluid cells and athymic nude mice.

Insight into the Effects of Reinforcement Shape on Achieving Continuous Martensite Transformation in Phase Transforming Matrix Composites

NASA Astrophysics Data System (ADS)

Zhang, Xudong; Ren, Junqiang; Wang, Xiaofei; Zong, Hongxiang; Cui, Lishan; Ding, Xiangdong

2017-12-01

A continuous martensite transformation is indispensable for achieving large linear superelasticity and low modulus in phase transforming metal-based composites. However, determining how to accurately condition the residual martensite in a shape memory alloy matrix though the reinforcement shape to achieve continuous martensite transformation has been a challenge. Here, we take the finite element method to perform a comparative study of the effects of nanoinclusion shape on the interaction and martensite phase transformation in this new composite. Two typical samples are compared: one reinforced by metallic nanowires and the other by nanoparticles. We find that the residual martensite within the shape memory alloy matrix after a pretreatment can be tailored by the reinforcement shape. In particular, our results show that the shape memory alloy matrix can retain enough residual martensite phases to achieve continuous martensite transformation in the subsequent loading when the aspect ratio of nanoreinforcement is larger than 20. In contrast, the composites reinforced with spherical or low aspect ratio reinforcement show a typical nonlinear superelasticity as a result of a low stress transfer-induced discontinuous martensite transformation within the shape memory alloy matrix.

Spatially resolved surface valence gradient and structural transformation of lithium transition metal oxides in lithium-ion batteries.

PubMed

Liu, Hanshuo; Bugnet, Matthieu; Tessaro, Matteo Z; Harris, Kristopher J; Dunham, Mark J R; Jiang, Meng; Goward, Gillian R; Botton, Gianluigi A

2016-10-26

Layered lithium transition metal oxides are one of the most important types of cathode materials in lithium-ion batteries (LIBs) that possess high capacity and relatively low cost. Nevertheless, these layered cathode materials suffer structural changes during electrochemical cycling that could adversely affect the battery performance. Clear explanations of the cathode degradation process and its initiation, however, are still under debate and not yet fully understood. We herein systematically investigate the chemical evolution and structural transformation of the LiNi x Mn y Co 1-x-y O 2 (NMC) cathode material in order to understand the battery performance deterioration driven by the cathode degradation upon cycling. Using high-resolution electron energy loss spectroscopy (HR-EELS) we clarify the role of transition metals in the charge compensation mechanism, particularly the controversial Ni 2+ (active) and Co 3+ (stable) ions, at different states-of-charge (SOC) under 4.6 V operation voltage. The cathode evolution is studied in detail from the first-charge to long-term cycling using complementary diagnostic tools. With the bulk sensitive 7 Li nuclear magnetic resonance (NMR) measurements, we show that the local ordering of transition metal and Li layers (R3[combining macron]m structure) is well retained in the bulk material upon cycling. In complement to the bulk measurements, we locally probe the valence state distribution of cations and the surface structure of NMC particles using EELS and scanning transmission electron microscopy (STEM). The results reveal that the surface evolution of NMC is initiated in the first-charging step with a surface reduction layer formed at the particle surface. The NMC surface undergoes phase transformation from the layered structure to a poor electronic and ionic conducting transition-metal oxide rock-salt phase (R3[combining macron]m → Fm3[combining macron]m), accompanied by irreversible lithium and oxygen loss. In addition to

An improved ternary vector system for Agrobacterium-mediated rapid maize transformation.

PubMed

Anand, Ajith; Bass, Steven H; Wu, Emily; Wang, Ning; McBride, Kevin E; Annaluru, Narayana; Miller, Michael; Hua, Mo; Jones, Todd J

2018-05-01

A simple and versatile ternary vector system that utilizes improved accessory plasmids for rapid maize transformation is described. This system facilitates high-throughput vector construction and plant transformation. The super binary plasmid pSB1 is a mainstay of maize transformation. However, the large size of the base vector makes it challenging to clone, the process of co-integration is cumbersome and inefficient, and some Agrobacterium strains are known to give rise to spontaneous mutants resistant to tetracycline. These limitations present substantial barriers to high throughput vector construction. Here we describe a smaller, simpler and versatile ternary vector system for maize transformation that utilizes improved accessory plasmids requiring no co-integration step. In addition, the newly described accessory plasmids have restored virulence genes found to be defective in pSB1, as well as added virulence genes. Testing of different configurations of the accessory plasmids in combination with T-DNA binary vector as ternary vectors nearly doubles both the raw transformation frequency and the number of transformation events of usable quality in difficult-to-transform maize inbreds. The newly described ternary vectors enabled the development of a rapid maize transformation method for elite inbreds. This vector system facilitated screening different origins of replication on the accessory plasmid and T-DNA vector, and four combinations were identified that have high (86-103%) raw transformation frequency in an elite maize inbred.

Ultrafast fluorescent decay induced by metal-mediated dipole–dipole interaction in two-dimensional molecular aggregates

DOE PAGES

Hu, Qing; Jin, Dafei; Xiao, Jun; ...

2017-09-05

Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the conventional (single or colloidal) dye molecules and quantum dots. Here, in this paper, we verify that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at a picosecond timescale. Our streak-camera lifetime measurement and interacting lattice–dipole calculation reveal that the metal-mediated dipole–dipole interaction shortens the fluorescent lifetime to about one-halfmore » and increases the energy dissipation rate by 10 times that expected from the noninteracting single-dipole picture. In conclusion, our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a unique direction for developing fast and efficient optoelectronic devices.« less

Characterization of buried metal-molecule-metal junctions using Fourier transform infrared microspectroscopy

NASA Astrophysics Data System (ADS)

Babayco, Christopher B.; Land, Donald P.; Parikh, Atul N.; Kiehl, Richard A.

2014-09-01

We have devised an infrared spectromicroscopy based experimental configuration to enable structural characterization of buried molecular junctions. Our design utilizes a small mercury drop at the focal point of an infrared microscope to act as a mirror in studying metal-molecule-metal (MmM) junctions. An organic molecular monolayer is formed either directly on the mercury drop or on a thin, infrared (IR) semi-transparent layer of Au deposited onto an IR transparent, undoped silicon substrate. Following the formation of the monolayer, films on either metal can be examined independently using specular reflection spectroscopy. Furthermore, by bringing together the two monolayers, a buried molecular bilayer within the MmM junction can be characterized. Independent examination of each half of the junction prior to junction formation also allows probing any structural and/or conformational changes that occur as a result of forming the bilayer. Because our approach allows assembling and disassembling microscopic junctions by forming and withdrawing Hg drops onto the monolayer covered metal, spatial mapping of junctions can be performed simply by translating the location of the derivatized silicon wafer. Finally, the applicability of this technique for the longer-term studies of changes in molecular structure in the presence of electrical bias is discussed.

Biochemical transformation of solid carbonaceous material

DOEpatents

Lin, Mow S.; Premuzic, Eugene T.

2001-09-25

A method of biochemically transforming macromolecular compounds found in solid carbonaceous materials, such as coal is provided. The preparation of new microorganisms, metabolically weaned through challenge growth processes to biochemically transform solid carbonaceous materials at extreme temperatures, pressures, pH, salt and toxic metal concentrations is also disclosed.

A Conserved Metal Binding Motif in the Bacillus subtilis Competence Protein ComFA Enhances Transformation.

PubMed

Chilton, Scott S; Falbel, Tanya G; Hromada, Susan; Burton, Briana M

2017-08-01

Genetic competence is a process in which cells are able to take up DNA from their environment, resulting in horizontal gene transfer, a major mechanism for generating diversity in bacteria. Many bacteria carry homologs of the central DNA uptake machinery that has been well characterized in Bacillus subtilis It has been postulated that the B. subtilis competence helicase ComFA belongs to the DEAD box family of helicases/translocases. Here, we made a series of mutants to analyze conserved amino acid motifs in several regions of B. subtilis ComFA. First, we confirmed that ComFA activity requires amino acid residues conserved among the DEAD box helicases, and second, we show that a zinc finger-like motif consisting of four cysteines is required for efficient transformation. Each cysteine in the motif is important, and mutation of at least two of the cysteines dramatically reduces transformation efficiency. Further, combining multiple cysteine mutations with the helicase mutations shows an additive phenotype. Our results suggest that the helicase and metal binding functions are two distinct activities important for ComFA function during transformation. IMPORTANCE ComFA is a highly conserved protein that has a role in DNA uptake during natural competence, a mechanism for horizontal gene transfer observed in many bacteria. Investigation of the details of the DNA uptake mechanism is important for understanding the ways in which bacteria gain new traits from their environment, such as drug resistance. To dissect the role of ComFA in the DNA uptake machinery, we introduced point mutations into several motifs in the protein sequence. We demonstrate that several amino acid motifs conserved among ComFA proteins are important for efficient transformation. This report is the first to demonstrate the functional requirement of an amino-terminal cysteine motif in ComFA. Copyright © 2017 American Society for Microbiology.

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

PubMed Central

2017-01-01

As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal–oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal–oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron–oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we

The Effects of Transformational Leadership and Mediating Factors on the Organizational Success Using Structural Equation Modeling: A Case Study.

PubMed

Ravangard, Ramin; Karimi, Sakine; Farhadi, Payam; Sajjadnia, Zahra; Shokrpour, Nasrin

This study was undertaken to determine the effects of transformational leadership (TL) and mediating factors on organizational success (OS) from the administrative, financial, and support employees' perspective in teaching hospitals affiliated with Shiraz University of Medical Sciences using structural equation modeling. Three hundred administrative and financial employees were selected, using stratified sampling proportional to size and simple random sampling. Data were collected using 5 questionnaires and analyzed using SPSS 21.0 and Lisrel 8.5 through Pearson correlation coefficient and path analysis and confirmatory factor analysis methods. Results showed that TL had significant positive effects on the 3 mediating factors, including organizational culture (t = 15.31), organizational citizenship behavior (OCB) (t = 10.06), and social capital (t = 10.25). Also, the organizational culture (t = 2.26), OCB (t = 3.48), and social capital (t = 7.41) had significant positive effects on OS. According to the results, TL had an indirect effect on OS. Therefore, organizations can achieve more success by strengthening organizational culture, OCB, and social capital through using transformational leadership style. Therefore, in order to increase OS, the following recommendations are made: supporting and encouraging new ideas in the organization, promoting teamwork, strengthening intergroup and intragroup relationships, planning to strengthen and enrich the social and organizational culture, considering the promotion of social capital in the employee training, establishing a system to give rewards to the employees performing extra-role activities, providing a suitable environment for creative employees, and so on.

The Mediating Effect of Social Capital on the Relationship Between Public Health Managers' Transformational Leadership and Public Health Nurses' Organizational Empowerment in Korea Public Health.

PubMed

Jun, Soo Young

2017-12-01

This study was to verify the effect of public health nurse's (PHN's) social capital on the relationship between public health manager's (PHM's) transformational leadership and PHN's organizational empowerment in Korea public health. This was a cross-sectional descriptive study involving 303 PHNs from public health centers in Daegu and Gyeongsangbuk-do cities in South Korea. Data were collected from February 29, 2016 to April 8, 2016, using structured questionnaires which included general characteristics, transformational leadership, organizational empowerment, and social capital. Data were analyzed using descriptive statistics, correlations, and structural equation model. PHM's transformational leadership has a positive effect on PHN's social capital and PHN's organizational empowerment. Social capital had a mediating effect between transformational leadership and organizational empowerment in PHNs. This study suggests that PHM's transformational leadership is a contributing factor to improve PHN's organizational empowerment, and transformational leadership can lead to improve PHN's organizational empowerment through PHN's social capital. So, an intervention program to promote organizational empowerment should include strategies to enhance PHM's transformational leadership as well as to improve PHN's social capital. Copyright © 2017. Published by Elsevier B.V.

A new and efficient approach for construction of uridine/uracil auxotrophic mutants in the filamentous fungus Aspergillus oryzae using Agrobacterium tumefaciens-mediated transformation.

PubMed

Nguyen, Khuyen Thi; Ho, Quynh Ngoc; Do, Loc Thi Binh Xuan; Mai, Linh Thi Dam; Pham, Duc-Ngoc; Tran, Huyen Thi Thanh; Le, Diep Hong; Nguyen, Huy Quang; Tran, Van-Tuan

2017-06-01

Aspergillus oryzae is a filamentous fungus widely used in food industry and as a microbial cell factory for recombinant protein production. Due to the inherent resistance of A. oryzae to common antifungal compounds, genetic transformation of this mold usually requires auxotrophic mutants. In this study, we show that Agrobacterium tumefaciens-mediated transformation (ATMT) method is very efficient for deletion of the pyrG gene in different Aspergillus oryzae wild-type strains to generate uridine/uracil auxotrophic mutants. Our data indicated that all the obtained uridine/uracil auxotrophic transformants, which are 5- fluoroorotic acid (5-FOA) resistant, exist as the pyrG deletion mutants. Using these auxotrophic mutants and the pyrG selectable marker for genetic transformation via A. tumefaciens, we could get about 1060 transformants per 10 6 fungal spores. In addition, these A. oryzae mutants were also used successfully for expression of the DsRed fluorescent reporter gene under control of the A. oryzae amyB promoter by the ATMT method, which resulted in obvious red transformants on agar plates. Our work provides a new and effective approach for constructing the uridine/uracil auxotrophic mutants in the importantly industrial fungus A. oryzae. This strategy appears to be applicable to other filamentous fungi to develop similar genetic transformation systems based on auxotrophic/nutritional markers for food-grade recombinant applications.

BIOMETHYLATION AND ENVIRONMENTAL TRANSPORT OF METALS

EPA Science Inventory

Toxic heavy metals are ubiquitous in the environment. They are found as metal or oxide dust in air, metal ions attached to humic substances in surface and ground water, and as metal ions bound to soils and sediments. The transformations, mobilization, transport, and bioaccumulati...

Fourier transform infrared isotopic studies on novel metal-carbon clusters trapped in argon matrix environments

NASA Astrophysics Data System (ADS)

Bates, Sarah Anne

The characterization of the vibrational spectra and structures of small metal-carbon (MnCm) clusters is important to the detection of astrophysical species and may elucidate the bonding and growth mechanisms of metallocarbohedrenes, or metcars. Additionally, transition metal-carbon clusters have applications in modern materials science as catalysts for nanomaterial formation. A new experimental apparatus for the preparation of MnC m clusters has been designed and constructed, incorporating a new closed cycle refrigeration system, a chamber for the deposition of samples, associated vacuum system, and a fully automated mechanism to simultaneously translate and rotate carbon and metal rods during laser ablation. A new technique for fabricating carbon rods has been developed to expedite carbon rod production and to facilitate the formation of the MnC m clusters studied. Fourier transform infrared (FTIR) investigations have been done for the first time on transition metal-carbon clusters. The molecular clusters were formed by trapping the products from dual laser ablation of metal and carbon rods in solid Ar at ˜10 K. Comparing FTIR measurements of vibrational fundamentals and 13C isotopic shifts with the predictions of density functional theory (DFT) calculations has enabled the identification of five novel metal-carbon molecules, establishing their ground state geometries and permitting the assignment of vibrational fundamentals, including the nu 1(sigma) modes of (5pi) linear CrC3, ( 2Delta) linear CoC3, and (2pi) linear CuC3 at 1789.5, 1918.2, and 1830.0 cm-1, respectively, the nu3(sigmau)=1624.0 and nu 4(sigmau)=528.3 cm-1 modes of (1Sigmag+) linear AlC3Al, and the nu2(sigma)=1210.9 cm -1 mode of linear AlC3. Evidence for the tentative identification of the nu1(a1)=1554.3 cm-1 mode of (3B1) fanlike CrC4 and the nu4(sigmau)=1987.3 cm-1 mode of (1Sigmag +) linear AlC4Al is also presented. All FTIR measurements of vibrational frequencies and 13C shifts are in very

Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

PubMed

Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

2015-11-23

Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment.

Spatial variance of POPs and heavy metals in transformer oil-contaminated soil around Tamil Nadu.

PubMed

Murugan, Karuvelan; Vasudevan, Namasivayam

2017-09-05

The persistent organic pollutants in the environment are one of the global issues to their unregulated disposal and informal recycling. This study investigates the contamination of soil with polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), phenolic compounds and heavy metals via spillage of transformer oil (TO). Fresh TO (FTO), used TO (UTO) and soil samples were analysed using GC-MS to confirm the presence of 8 PCB congeners, 16 PAHs and 24 types of phenolic compounds and using inductively coupled plasma optical emission spectrometry to confirm the presence of 7 heavy metals. The chromatographic analysis revealed the levels of mono-, di-, tri-, tetra-, penta-, hexa-, hepta- and octachlorobiphenyls in FTO to be 5.63, 25.24, 0.195, 0.185, 2.169, 1.023 and 5.28 mg/L and the level of mono-, di-, tri-, tetra-, penta- and hexachlorobiphenyls in UTO to be 0.27, 1.21, 1.31, 0.80, 1.77 and 3.90 mg/L. Analysis of soil from 10 different TO-contaminated sites showed the presence of PCBs, PAHs, phenolic compounds and heavy metals in the concentration range of 0.53-42.87 mg/kg, 3.19-246.6 μg/kg, 0.01-4086.45 μg/kg and 1.0-401.3 mg/kg, respectively. The variation in the concentration of these compounds and heavy metals among different sampling sites was determined using principal component analysis (PCA), metric multi-dimensional scaling (MDS) and Bray-Curtis cluster analysis (Bu-CA). The toxicity equivalence factor and the mechanism involved in the disruption of endocrine system are discussed. Thus, this study exemplifies the need for complete ban of PCB-containing TOs in developing countries and urges the need for technology for the disposal of TO.

Mitogen-Inducible Gene-6 Mediates Feedback Inhibition from Mutated BRAF towards the Epidermal Growth Factor Receptor and Thereby Limits Malignant Transformation

PubMed Central

Milewska, Malgorzata; Romano, David; Herrero, Ana; Guerriero, Maria Luisa; Birtwistle, Marc; Quehenberger, Franz; Hatzl, Stefan; Kholodenko, Boris N.; Segatto, Oreste; Kolch, Walter; Zebisch, Armin

2015-01-01

BRAF functions in the RAS-extracellular signal-regulated kinase (ERK) signaling cascade. Activation of this pathway is necessary to mediate the transforming potential of oncogenic BRAF, however, it may also cause a negative feedback that inhibits the epidermal growth factor receptor (EGFR). Mitogen-inducible gene-6 (MIG-6) is a potent inhibitor of the EGFR and has been demonstrated to function as a tumor suppressor. As MIG-6 can be induced via RAS-ERK signaling, we investigated its potential involvement in this negative regulatory loop. Focus formation assays were performed and demonstrated that MIG-6 significantly reduces malignant transformation induced by oncogenic BRAF. Although this genetic interaction was mirrored by a physical interaction between MIG-6 and BRAF, we did not observe a direct regulation of BRAF kinase activity by MIG-6. Interestingly, a selective chemical EGFR inhibitor suppressed transformation to a similar degree as MIG-6, whereas combining these approaches had no synergistic effect. By analyzing a range of BRAF mutated and wildtype cell line models, we could show that BRAF V600E causes a strong upregulation of MIG-6, which was mediated at the transcriptional level via the RAS-ERK pathway and resulted in downregulation of EGFR activation. This feedback loop is operational in tumors, as shown by the analysis of almost 400 patients with papillary thyroid cancer (PTC). Presence of BRAF V600E correlated with increased MIG-6 expression on the one hand, and with inactivation of the EGFR and of PI3K/AKT signaling on the other hand. Importantly, we also observed a more aggressive disease phenotype when BRAF V600E coexisted with low MIG-6 expression. Finally, analysis of methylation data was performed and revealed that higher methylation of MIG-6 correlated to its decreased expression. Taken together, we demonstrate that MIG-6 efficiently reduces cellular transformation driven by oncogenic BRAF by orchestrating a negative feedback circuit directed

Highly Efficient Agrobacterium-Mediated Transformation of Wheat Via In Planta Inoculation

NASA Astrophysics Data System (ADS)

Risacher, Thierry; Craze, Melanie; Bowden, Sarah; Paul, Wyatt; Barsby, Tina

This chapter details a reproducible method for the transformation of spring wheat using Agrobacterium tumefaciens via the direct inoculation of bacteria into immature seeds in planta as described in patent WO 00/63398(1. Transformation efficiencies from 1 to 30% have been obtained and average efficiencies of at least 5% are routinely achieved. Regenerated plants are phenotypically normal with 30-50% of transformation events carrying introduced genes at single insertion sites, a higher rate than is typically reported for transgenic plants produced using biolistic transformation methods.

Agrobacterium-mediated transformation of Fraxinus pennsylvanica hypocotyls and plant regeneration

Treesearch

Ningxia Du; Paula M. Pijut

2009-01-01

A genetic transformation protocol for green ash (Fraxinus pennsylvanica) hypocotyl explants was developed. Green ash hypocotyls were transformed using Agrobacterium tumefaciens strain EHA105 harboring binary vector pq35GR containing the neomycin phosphotransferase (nptII) and β-glucuronidase (GUS) fusion...

Development of an Agrobacterium-mediated transformation system for the cold-adapted fungi Pseudogymnoascus destructans and P. pannorum.

PubMed

Zhang, Tao; Ren, Ping; Chaturvedi, Vishnu; Chaturvedi, Sudha

2015-08-01

The mechanisms of cold adaptation by fungi remain unknown. This topic is of high interest due to the emergence of white-nose syndrome (WNS), a skin infection of hibernating bats caused by Pseudogymnoascus destructans (Pd). Recent studies indicated that apart from Pd, there is an abundance of other Pseudogymnoascus species in the hibernacula soil. We developed an Agrobacterium tumefaciens-mediated transformation (ATMT) system for Pd and a related fungus Pseudogymnoascus pannorum (Pp) to advance experimental studies. URE1 gene encoding the enzyme urease was used as an easy to screen marker to facilitate molecular genetic analyses. A Uracil-Specific Excision Reagent (USER) Friendly pRF-HU2 vector containing Pd or Pp ure1::hygromycin (HYG) disruption cassette was introduced into A. tumefaciens AGL-1 cells by electroporation and the resulting strains were co-cultivated with conidia of Pd or Pp for various durations and temperatures to optimize the ATMT system. Overall, 680 Pd (0.006%) and 1800 Pp (0.018%) transformants were obtained from plating of 10(7) conidia; their recoveries were strongly correlated with the length of the incubation period (96h for Pd; 72h for Pp) and with temperature (15-18°C for Pd; 25°C for Pp). The homologous recombination in transformants was 3.1% for Pd and 16.7% for Pp. The availability of a standardized ATMT system would allow future molecular genetic analyses of Pd and related cold-adapted fungi. Copyright © 2015. Published by Elsevier Inc.

Educational Alchemy: The Transformation of Schools.

ERIC Educational Resources Information Center

Mugits, Michael James

Alchemy is the magical or mysterious power or process involving chemistry, magic, and philosophy in transforming one thing into another. The term is often used to describe the medieval study that sought to transform cheaper metals into gold or silver. "Educational alchemy" is the process by which schools are converted into more effective learning…

Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

NASA Astrophysics Data System (ADS)

Kamnev, A. A.; Antonyuk, L. P.; Tugarova, A. V.; Tarantilis, P. A.; Polissiou, M. G.; Gardiner, P. H. E.

2002-06-01

Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563-564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co2+, Cu2+ and Zn2+) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.

CRISPR/Cas9-mediated efficient genome editing via blastospore-based transformation in entomopathogenic fungus Beauveria bassiana.

PubMed

Chen, Jingjing; Lai, Yiling; Wang, Lili; Zhai, Suzhen; Zou, Gen; Zhou, Zhihua; Cui, Chunlai; Wang, Sibao

2017-04-03

Beauveria bassiana is an environmentally friendly alternative to chemical insecticides against various agricultural insect pests and vectors of human diseases. However, its application has been limited due to slow kill and sensitivity to abiotic stresses. Understanding of the molecular pathogenesis and physiological characteristics would facilitate improvement of the fungal performance. Loss-of-function mutagenesis is the most powerful tool to characterize gene functions, but it is hampered by the low rate of homologous recombination and the limited availability of selectable markers. Here, by combining the use of uridine auxotrophy as recipient and donor DNAs harboring auxotrophic complementation gene ura5 as a selectable marker with the blastospore-based transformation system, we established a highly efficient, low false-positive background and cost-effective CRISPR/Cas9-mediated gene editing system in B. bassiana. This system has been demonstrated as a simple and powerful tool for targeted gene knock-out and/or knock-in in B. bassiana in a single gene disruption. We further demonstrated that our system allows simultaneous disruption of multiple genes via homology-directed repair in a single transformation. This technology will allow us to study functionally redundant genes and holds significant potential to greatly accelerate functional genomics studies of B. bassiana.

CRISPR/Cas9-mediated efficient genome editing via blastospore-based transformation in entomopathogenic fungus Beauveria bassiana

PubMed Central

Chen, Jingjing; Lai, Yiling; Wang, Lili; Zhai, Suzhen; Zou, Gen; Zhou, Zhihua; Cui, Chunlai; Wang, Sibao

2017-01-01

Beauveria bassiana is an environmentally friendly alternative to chemical insecticides against various agricultural insect pests and vectors of human diseases. However, its application has been limited due to slow kill and sensitivity to abiotic stresses. Understanding of the molecular pathogenesis and physiological characteristics would facilitate improvement of the fungal performance. Loss-of-function mutagenesis is the most powerful tool to characterize gene functions, but it is hampered by the low rate of homologous recombination and the limited availability of selectable markers. Here, by combining the use of uridine auxotrophy as recipient and donor DNAs harboring auxotrophic complementation gene ura5 as a selectable marker with the blastospore-based transformation system, we established a highly efficient, low false-positive background and cost-effective CRISPR/Cas9-mediated gene editing system in B. bassiana. This system has been demonstrated as a simple and powerful tool for targeted gene knock-out and/or knock-in in B. bassiana in a single gene disruption. We further demonstrated that our system allows simultaneous disruption of multiple genes via homology-directed repair in a single transformation. This technology will allow us to study functionally redundant genes and holds significant potential to greatly accelerate functional genomics studies of B. bassiana. PMID:28368054

Activation of antioxidant pathways in ras-mediated oncogenic transformation of human surface ovarian epithelial cells revealed by functional proteomics and mass spectrometry.

PubMed

Young, Travis W; Mei, Fang C; Yang, Gong; Thompson-Lanza, Jennifer A; Liu, Jinsong; Cheng, Xiaodong

2004-07-01

Cellular transformation is a complex process involving genetic alterations associated with multiple signaling pathways. Development of a transformation model using defined genetic elements has provided an opportunity to elucidate the role of oncogenes and tumor suppressor genes in the initiation and development of ovarian cancer. To study the cellular and molecular mechanisms of Ras-mediated oncogenic transformation of ovarian epithelial cells, we used a proteomic approach involving two-dimensional electrophoresis and mass spectrometry to profile two ovarian epithelial cell lines, one immortalized with SV40 T/t antigens and the human catalytic subunit of telomerase and the other transformed with an additional oncogenic ras(V12) allele. Of approximately 2200 observed protein spots, we have identified >30 protein targets that showed significant changes between the immortalized and transformed cell lines using peptide mass fingerprinting. Among these identified targets, one most notable group of proteins altered significantly consists of enzymes involved in cellular redox balance. Detailed analysis of these protein targets suggests that activation of Ras-signaling pathways increases the threshold of reactive oxidative species (ROS) tolerance by up-regulating the overall antioxidant capacity of cells, especially in mitochondria. This enhanced antioxidant capacity protects the transformed cells from high levels of ROS associated with the uncontrolled growth potential of tumor cells. It is conceivable that an enhanced antioxidation capability may constitute a common mechanism for tumor cells to evade apoptosis induced by oxidative stresses at high ROS levels.

Modulation of nitric oxide-mediated metal release from metallothionein by the redox state of glutathione in vitro.

PubMed

Khatai, Leila; Goessler, Walter; Lorencova, Helena; Zangger, Klaus

2004-06-01

Metallothioneins (MTs) release bound metals when exposed to nitric oxide. At inflammatory sites, both metallothionein and inducible nitric oxide synthase (iNOS) are induced by the same factors and the zinc released from metallothionein by NO suppresses both the induction and activity of iNOS. In a search for a possible modulatory mechanism of this coexpression of counteracting proteins, we investigated the role of the glutathione redox state in vitro because the oxidation state of thiols is involved in the metal binding in Cd-S or Zn-S clusters found in metallothioneins, and NO also binds to reduced glutathione via S-nitrosation. Using a variety of techniques, we found that NO and also ONOO(-)-mediated metal release from purified MTs is suppressed by reduced glutathione (GSH), but not by oxidized glutathione. Considering the millimolar concentrations of GSH present in mammalian cells, the metal release from MTs by NO should play no role in living systems. Therefore, the fact that it has been observed in vivo points to a hitherto unknown mechanism or additional compound(s) being involved in this physiologically relevant reaction and as long as this additional factor is not found experimental results on the MT-NO interaction should be treated with caution. Contrary to the peroxynitrite-induced activation of guanylyl cyclase, where GSH is needed, we found that the metal release from metallothionein by peroxynitrite is not enhanced, but also suppressed by reduced glutathione. In addition, we show that zinc, the major natural metal ligand in mammalian MTs and suppressor of iNOS, is released more readily under the influence of NO than cadmium, but in contrast to the MT isoform 1, the amount of metal released from the beta-domain of MT-2 is comparable to that from the alpha-domain.

Transforming growth factor β-mediated suppression of antitumor T cells requires FoxP1 transcription factor expression.

PubMed

Stephen, Tom L; Rutkowski, Melanie R; Allegrezza, Michael J; Perales-Puchalt, Alfredo; Tesone, Amelia J; Svoronos, Nikolaos; Nguyen, Jenny M; Sarmin, Fahmida; Borowsky, Mark E; Tchou, Julia; Conejo-Garcia, Jose R

2014-09-18

Tumor-reactive T cells become unresponsive in advanced tumors. Here we have characterized a common mechanism of T cell unresponsiveness in cancer driven by the upregulation of the transcription factor Forkhead box protein P1 (Foxp1), which prevents CD8⁺ T cells from proliferating and upregulating Granzyme-B and interferon-γ in response to tumor antigens. Accordingly, Foxp1-deficient lymphocytes induced rejection of incurable tumors and promoted protection against tumor rechallenge. Mechanistically, Foxp1 interacted with the transcription factors Smad2 and Smad3 in preactivated CD8⁺ T cells in response to microenvironmental transforming growth factor-β (TGF-β), and was essential for its suppressive activity. Therefore, Smad2 and Smad3-mediated c-Myc repression requires Foxp1 expression in T cells. Furthermore, Foxp1 directly mediated TGF-β-induced c-Jun transcriptional repression, which abrogated T cell activity. Our results unveil a fundamental mechanism of T cell unresponsiveness different from anergy or exhaustion, driven by TGF-β signaling on tumor-associated lymphocytes undergoing Foxp1-dependent transcriptional regulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Ligand functionalization as a deactivation pathway in a fac-Ir(ppy)3-mediated radical addition.

PubMed

Devery Iii, James J; Douglas, James J; Nguyen, John D; Cole, Kevin P; Flowers Ii, Robert A; Stephenson, Corey R J

2015-01-01

Knowledge of the kinetic behavior of catalysts under synthetically relevant conditions is vital for the efficient use of compounds that mediate important transformations regardless of their composition or driving force. In particular, these data are of great importance to add perspective to the growing number of applications of photoactive transition metal complexes. Here we present kinetic, synthetic, and spectroscopic evidence of the mechanistic behavior of fac -Ir(ppy) 3 in a visible light-mediated radical addition to 3-methylindole, demonstrating the instability of fac -Ir(ppy) 3 under these conditions. During the reaction, rapid in situ functionalization of the photocatalyst occurs, eventually leading to deactivation. These findings demonstrate a conceivable deactivation process for catalytic single electron reactions in the presence of radicophilic ligands. Attempts to inhibit photocatalyst deactivation through structural modification provide further insight into catalyst selection for a given system of interest.

The mediating role of organizational justice in the relationship between transformational leadership and nurses' quality of work life: a cross-sectional questionnaire survey.

PubMed

Gillet, Nicolas; Fouquereau, Evelyne; Bonnaud-Antignac, Angélique; Mokounkolo, René; Colombat, Philippe

2013-10-01

The importance of transformational leadership for nurses' well-being is increasingly acknowledged. However, there is a paucity of research examining the mechanisms that may explain the relationships between transformational leadership and nurses' quality of work life. First, to examine two possible psychological mechanisms that link transformational leadership behaviors to nurses' quality of work life. Second, to study the relationship between nurses' quality of work life and their work engagement. Cross-sectional study design. The study took place in 47 different hematology, oncology, and hematology/oncology units in France. Participants were nurses and auxiliary nurses. 343 nurses completed the questionnaire. Surveys were sent to all nurses working in the units. 95% were female, the average age was 36.30 years. Nurses were asked to rate their supervisor's transformational leadership style and their perceptions of distributive and interactional justice in the unit. They were also asked to evaluate their own level of quality of work life and their work engagement. Distributive justice and interactional justice were found to fully mediate the relationship between transformational leadership and nurses' quality of work life. In addition, nurses' quality of work life positively related to their work engagement. Transformational leaders may help ensure nurses' quality of work life which in turn increases their work engagement. These leadership practices are thus beneficial for both employees and organization. Copyright © 2012 Elsevier Ltd. All rights reserved.

Selective Metal-Ion-Mediated Vesicle Adhesion Based on Dynamic Self-Organization of a Pyrene-Appended Glutamic Acid.

PubMed

Xing, Pengyao; Wang, Yajie; Yang, Minmin; Zhang, Yimeng; Wang, Bo; Hao, Aiyou

2016-07-13

Vesicles with dynamic membranes provide an ideal model system for investigating biological membrane activities, whereby vesicle aggregation behaviors including adhesion, fusion, fission, and membrane contraction/extension have attracted much attention. In this work we utilize an aromatic amino acid (pyrene-appended glutamic acid, PGlu) to prepare nanovesicles that aggregate to form vesicle clusters selectively induced by Fe(3+) or Cu(2+), and the vesicles transform into irregular nano-objects when interacting with Al(3+). Vesicle clusters have better stability than pristine vesicles, which hinders the spontaneous morphological transformation from vesicles into lamellar nanosheets with long incubation period. The difference between complexation of Fe(3+) and Al(3+) with vesicles was studied by various techniques. On the basis of metal ion-vesicle interactions, this self-assembled nanovesicle system also behaves as an effective fluorescent sensor for Fe(3+) and Al(3+), which cause fluorescence quenching and enhanced excimer emission, respectively.

Highly efficient Agrobacterium-mediated transformation of embryogenic cell suspensions of Musa acuminata cv. Mas (AA) via a liquid co-cultivation system.

PubMed

Huang, Xia; Huang, Xue-Lin; Xiao, Wang; Zhao, Jie-Tang; Dai, Xue-Mei; Chen, Yun-Feng; Li, Xiao-Ju

2007-10-01

A high efficient protocol of Agrobacterium-mediated transformation of Musa acuminata cv. Mas (AA), a major banana variety of the South East Asia region, was developed in this study. Male-flower-derived embryogenic cell suspensions (ECS) were co-cultivated in liquid medium with Agrobacterium strain EHA105 harboring a binary vector pCAMBIA2301 carrying nptII and gusA gene in the T-DNA. Depending upon conditions and duration of co-cultivation in liquid medium, 0-490 transgenic plants per 0.5 ml packed cell volume (PCV) of ECS were obtained. The optimum duration of inoculation was 2 h, and the highest transformation frequency was achieved when infected ECS were co-cultivated in liquid medium first for 12 h at 40 rpm and then for 156 h at 100 rpm on a rotary shaker. Co-cultivation for a shorter duration (72 h) or shaking constantly at 100 rpm at the same duration gave 1.6 and 1.8 folds lower transformation efficiency, respectively. No transgenic plants were obtained in parallel experiments carried on semi-solid media. Histochemical GUS assay and molecular analysis in several tissues of the transgenic plants demonstrated that foreign genes were stably integrated into the banana genome. Compared to semi-solid co-cultivation transformation in other banana species, it is remarkable that liquid co-cultivation was much more efficient for transformation of the Mas cultivar, and was at least 1 month faster for regenerating transgenic plants.

Alkali-Metal-Mediated Magnesiations of an N-Heterocyclic Carbene: Normal, Abnormal, and "Paranormal" Reactivity in a Single Tritopic Molecule.

PubMed

Martínez-Martínez, Antonio J; Fuentes, M Ángeles; Hernán-Gómez, Alberto; Hevia, Eva; Kennedy, Alan R; Mulvey, Robert E; O'Hara, Charles T

2015-11-16

Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr(2-). Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr(-) monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ROLES OF EPIDERMAL GROWTH FACTOR (EGF) AND TRANSFORMING GROWTH FACTOR-ALPHA (TGF-A) IN MEDIATION OF DIOXIN (TCDD)-INDUCED DELAYS IN DEVELOPMENT OF THE MOUSE MAMMARY GLAND

EPA Science Inventory

Roles of Epidermal Growth Factor (EGF) and Transforming Growth Factor-alpha (TGF-a) in Mediation of Dioxin (TCDD)-Induced Delays in Development of the Mouse Mammary Gland.
Suzanne E. Fenton, Barbara Abbott, Lamont Bryant, and Angela Buckalew. U.S. EPA, NHEERL, Reproductive Tox...

Solvent-induced controllable synthesis, single-crystal to single-crystal transformation and encapsulation of Alq3 for modulated luminescence in (4,8)-connected metal-organic frameworks.

PubMed

Lan, Ya-Qian; Jiang, Hai-Long; Li, Shun-Li; Xu, Qiang

2012-07-16

In this work, for the first time, we have systematically demonstrated that solvent plays crucial roles in both controllable synthesis of metal-organic frameworks (MOFs) and their structural transformation process. With solvent as the only variable, five new MOFs with different structures have been constructed, in which one MOF undergoes solvent-induced single-crystal to single-crystal (SCSC) transformation that involves not only solvent exchange but also the cleavage and formation of coordination bonds. Particularly, a significant crystallographic change has been realized through an unprecedented three-step SCSC transformation process. Furthermore, we have demonstrated that the obtained MOF could be an excellent host for chromophores such as Alq3 for modulated luminescent properties.

Leaching behavior of heavy metals and transformation of their speciation in polluted soil receiving simulated acid rain.

PubMed

Zheng, Shun-an; Zheng, Xiangqun; Chen, Chun

2012-01-01

Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.

Leaching Behavior of Heavy Metals and Transformation of Their Speciation in Polluted Soil Receiving Simulated Acid Rain

PubMed Central

Zheng, Shun-an; Zheng, Xiangqun; Chen, Chun

2012-01-01

Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects. PMID:23185399

Phase transformations at interfaces: Observations from atomistic modeling

DOE PAGES

Frolov, T.; Asta, M.; Mishin, Y.

2016-10-01

Here, we review the recent progress in theoretical understanding and atomistic computer simulations of phase transformations in materials interfaces, focusing on grain boundaries (GBs) in metallic systems. Recently developed simulation approaches enable the search and structural characterization of GB phases in single-component metals and binary alloys, calculation of thermodynamic properties of individual GB phases, and modeling of the effect of the GB phase transformations on GB kinetics. Atomistic simulations demonstrate that the GB transformations can be induced by varying the temperature, loading the GB with point defects, or varying the amount of solute segregation. The atomic-level understanding obtained from suchmore » simulations can provide input for further development of thermodynamics theories and continuous models of interface phase transformations while simultaneously serving as a testing ground for validation of theories and models. They can also help interpret and guide experimental work in this field.« less

Methane combustion reactivity during the metal→metallic oxide transformation of Pd-Pt catalysts: Effect of oxygen pressure

NASA Astrophysics Data System (ADS)

Qi, Wenjie; Ran, Jingyu; Zhang, Zhien; Niu, Juntian; Zhang, Peng; Fu, Lijuan; Hu, Bo; Li, Qilai

2018-03-01

Density functional theory combined with kinetic models were used to probe different kinetics consequences by which methane activation on different oxygen chemical potential surfaces as oxygen pressure increased. The metallic oxide → metal transformation temperature of Pd-Pt catalysts increased with the increase of the Pd content or/and O2 pressure. The methane conversion rate on Pt catalyst increased and then decreased to a constant value when increasing the O2 pressure, and Pd catalyst showed a poor activity performance in the case of low O2 pressure. Moreover, its activity increased as the oxygen chemical potential for O2 pressure increased in the range of 2.5-10 KPa. For metal clusters, the Csbnd H bond and Odbnd O bond activation steps occurred predominantly on *-* site pairs. The methane conversion rate was determined by O2 pressure because the adsorbed O atoms were rapidly consumed by other adsorbed species in this kinetic regime. As the O2 pressure increased, the metallic active sites for methane activation were decreased and there was no longer lack of adsorbed O atoms, resulting in the decrease of the methane conversion rate. Furthermore, when the metallic surfaces were completely covered by adsorbed oxygen atoms at higher oxygen chemical potentials, Pt catalyst showed a poor activity due to a high Csbnd H bond activation barrier on O*sbnd O*. In the case of high O2 pressure, Pd atoms preferred to segregate to the active surface of Pd-Pt catalysts, leading to the formation of PdO surfaces. The increase of Pd segregation promoted a subsequent increase in active sites and methane conversion rate. The PdO was much more active than metallic and O* saturated surfaces for methane activation, inferred from the theory and experimental study. Pd-rich bimetallic catalyst (75% molar Pd) showed a dual high methane combustion activity on O2-poor and O2-rich conditions.

Transformation of taxol-producing endophytic fungi by restriction enzyme-mediated integration (REMI).

PubMed

Wang, Yechun; Guo, Binhui; Miao, Zhiqi; Tang, Kexuan

2007-08-01

The REMI method was used to introduce the plasmid pV2 harboring the hygromycin B phosphotransferase (hph) gene controlled by the Aspergillus nidulans trpC promoter and the trpC terminator into a taxol-producing endophytic fungus BT2. REMI transformation yielded stable transformants capable of continuing to grow on PDA medium containing 125 mug mL(-1) hygromycin B. The transformation efficiency was about 5-6 transformants mug(-1) plasmid DNA. The presence of hph gene in transformants was confirmed by PCR and Southern blot analyses. To the authors' knowledge, this is the first report on the transformation of taxol-producing endophytic fungi by the REMI technique. This study provides an effective approach for improving taxol production of endophytic fungi by the genetic engineering of taxol biosynthetic pathway genes in the future.

Evaluation of parameters affecting switchgrass tissue culture: toward a consolidated procedure for Agrobacterium-mediated transformation of switchgrass (Panicum virgatum)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Chien-Yuan; Donohoe, Bryon S.; Ahuja, Neha

Switchgrass (Panicum virgatum), a robust perennial C4-type grass, has been evaluated and designated as a model bioenergy crop by the U.S. DOE and USDA. Conventional breeding of switchgrass biomass is difficult because it displays self-incompatible hindrance. Therefore, direct genetic modifications of switchgrass have been considered the more effective approach to tailor switchgrass with traits of interest. Successful transformations have demonstrated increased biomass yields, reduction in the recalcitrance of cell walls and enhanced saccharification efficiency. Several tissue culture protocols have been previously described to produce transgenic switchgrass lines using different nutrient-based media, co-cultivation approaches, and antibiotic strengths for selection. After evaluatingmore » the published protocols, we consolidated these approaches and optimized the process to develop a more efficient protocol for producing transgenic switchgrass. First, seed sterilization was optimized, which led to a 20% increase in yield of induced calluses. Second, we have selected a N 6 macronutrient/B 5 micronutrient (NB)-based medium for callus induction from mature seeds of the Alamo cultivar, and chose a Murashige and Skoog-based medium to regenerate both Type I and Type II calluses. Third, Agrobacterium-mediated transformation was adopted that resulted in 50-100% positive regenerated transformants after three rounds (2 weeks/round) of selection with antibiotic. Genomic DNA PCR, RT-PCR, Southern blot, visualization of the red fluorescent protein and histochemical β-glucuronidase (GUS) staining were conducted to confirm the positive switchgrass transformants. The optimized methods developed here provide an improved strategy to promote the production and selection of callus and generation of transgenic switchgrass lines. The process for switchgrass transformation has been evaluated and consolidated to devise an improved approach for transgenic switchgrass production. With

Evaluation of parameters affecting switchgrass tissue culture: toward a consolidated procedure for Agrobacterium-mediated transformation of switchgrass (Panicum virgatum)

DOE PAGES

Lin, Chien-Yuan; Donohoe, Bryon S.; Ahuja, Neha; ...

2017-12-19

Switchgrass (Panicum virgatum), a robust perennial C4-type grass, has been evaluated and designated as a model bioenergy crop by the U.S. DOE and USDA. Conventional breeding of switchgrass biomass is difficult because it displays self-incompatible hindrance. Therefore, direct genetic modifications of switchgrass have been considered the more effective approach to tailor switchgrass with traits of interest. Successful transformations have demonstrated increased biomass yields, reduction in the recalcitrance of cell walls and enhanced saccharification efficiency. Several tissue culture protocols have been previously described to produce transgenic switchgrass lines using different nutrient-based media, co-cultivation approaches, and antibiotic strengths for selection. After evaluatingmore » the published protocols, we consolidated these approaches and optimized the process to develop a more efficient protocol for producing transgenic switchgrass. First, seed sterilization was optimized, which led to a 20% increase in yield of induced calluses. Second, we have selected a N 6 macronutrient/B 5 micronutrient (NB)-based medium for callus induction from mature seeds of the Alamo cultivar, and chose a Murashige and Skoog-based medium to regenerate both Type I and Type II calluses. Third, Agrobacterium-mediated transformation was adopted that resulted in 50-100% positive regenerated transformants after three rounds (2 weeks/round) of selection with antibiotic. Genomic DNA PCR, RT-PCR, Southern blot, visualization of the red fluorescent protein and histochemical β-glucuronidase (GUS) staining were conducted to confirm the positive switchgrass transformants. The optimized methods developed here provide an improved strategy to promote the production and selection of callus and generation of transgenic switchgrass lines. The process for switchgrass transformation has been evaluated and consolidated to devise an improved approach for transgenic switchgrass production. With

Metals, minerals and microbes: geomicrobiology and bioremediation.

PubMed

Gadd, Geoffrey Michael

2010-03-01

Microbes play key geoactive roles in the biosphere, particularly in the areas of element biotransformations and biogeochemical cycling, metal and mineral transformations, decomposition, bioweathering, and soil and sediment formation. All kinds of microbes, including prokaryotes and eukaryotes and their symbiotic associations with each other and 'higher organisms', can contribute actively to geological phenomena, and central to many such geomicrobial processes are transformations of metals and minerals. Microbes have a variety of properties that can effect changes in metal speciation, toxicity and mobility, as well as mineral formation or mineral dissolution or deterioration. Such mechanisms are important components of natural biogeochemical cycles for metals as well as associated elements in biomass, soil, rocks and minerals, e.g. sulfur and phosphorus, and metalloids, actinides and metal radionuclides. Apart from being important in natural biosphere processes, metal and mineral transformations can have beneficial or detrimental consequences in a human context. Bioremediation is the application of biological systems to the clean-up of organic and inorganic pollution, with bacteria and fungi being the most important organisms for reclamation, immobilization or detoxification of metallic and radionuclide pollutants. Some biominerals or metallic elements deposited by microbes have catalytic and other properties in nanoparticle, crystalline or colloidal forms, and these are relevant to the development of novel biomaterials for technological and antimicrobial purposes. On the negative side, metal and mineral transformations by microbes may result in spoilage and destruction of natural and synthetic materials, rock and mineral-based building materials (e.g. concrete), acid mine drainage and associated metal pollution, biocorrosion of metals, alloys and related substances, and adverse effects on radionuclide speciation, mobility and containment, all with immense social

Green Synthesis of Cyclodextrin-Based Metal-Organic Frameworks through the Seed-Mediated Method for the Encapsulation of Hydrophobic Molecules.

PubMed

Qiu, Chao; Wang, Jinpeng; Qin, Yang; Fan, Haoran; Xu, Xueming; Jin, Zhengyu

2018-04-25

Metal-organic frameworks (MOFs) are attracting considerable attention as a result of their unique structural properties, such as a high surface area, highly porous topology, and tunable size and shape, which enable them to have potential applications as a new class of carriers for functional agent or drug delivery. However, most of the MOFs and the polymers used are not pharmaceutically acceptable. For the first time, this study successfully conducted the rapid synthesis of cyclodextrin metal-organic frameworks (CD-MOFs) through a facile and green seed-mediated method. The size control, crystal structure, and thermal properties of CD-MOFs with and without seeds were investigated. When 1 mg/mL seed was added, the size of γ-CD-MOF crystals decreased from 6.2 ± 0.8 to 1.8 ± 0.4 μm. The CD-MOFs synthesized though the seed-mediated method had higher crystallinity and thermal stability than those that were not. Furthermore, the CD-MOFs could encapsulate hydrophobic molecules, such as Nile red (NR), which was chosen as a model, and the interaction mechanism between γ-CD-MOFs and NR was investigated. Results showed the formation of a 1:1 complex between NR and CD-MOFs, demonstrating the potential of these polymers as carriers for hydrophobic drug delivery applications.

Toehold-mediated internal control to probe the near-field interaction between the metallic nanoparticle and the fluorophore

NASA Astrophysics Data System (ADS)

Ang, Y. S.; Yung, L. Y. L.

2014-10-01

Metallic nanoparticles (MNPs) are known to alter the emission of vicinal fluorophores through the near-field interaction, leading to either fluorescence quenching or enhancement. Much ambiguity remains in the experimental outcome of such a near-field interaction, particularly for bulk colloidal solution. It is hypothesized that the strong far-field interference from the inner filter effect of the MNPs could mask the true near-field MNP-fluorophore interaction significantly. Thus, in this work, a reliable internal control capable of decoupling the near-field interaction from far-field interference is established by the use of the DNA toehold concept to mediate the in situ assembly and disassembly of the MNP-fluorophore conjugate. A model gold nanoparticle (AuNP)-Cy3 system is used to investigate our proposed toehold-mediated internal control system. The maximum fluorescence enhancement is obtained for large-sized AuNP (58 nm) separated from Cy3 at an intermediate distance of 6.8 nm, while fluorescence quenching is observed for smaller-sized AuNP (11 nm and 23 nm), which is in agreement with the theoretical values reported in the literature. This work shows that the toehold-mediated internal control design can serve as a central system for evaluating the near-field interaction of other MNP-fluorophore combinations and facilitate the rational design of specific MNP-fluorophore systems for various applications.Metallic nanoparticles (MNPs) are known to alter the emission of vicinal fluorophores through the near-field interaction, leading to either fluorescence quenching or enhancement. Much ambiguity remains in the experimental outcome of such a near-field interaction, particularly for bulk colloidal solution. It is hypothesized that the strong far-field interference from the inner filter effect of the MNPs could mask the true near-field MNP-fluorophore interaction significantly. Thus, in this work, a reliable internal control capable of decoupling the near

The Effects of Integrated Transformational Leadership on Achievement

ERIC Educational Resources Information Center

Boberg, John Eric; Bourgeois, Steven J.

2016-01-01

Purpose: Greater understanding about how variables mediate the relationship between leadership and achievement is essential to the success of reform efforts that hold leaders accountable for student learning. The purpose of this paper is to test a model of integrated transformational leadership including three important school mediators.…

Transforming growth factor β-induced expression of chondroitin sulfate proteoglycans is mediated through non-Smad signaling pathways.

PubMed

Jahan, Naima; Hannila, Sari S

2015-01-01

The expression of chondroitin sulfate proteoglycans (CSPGs) by reactive astrocytes is a major factor contributing to glial scarring and regenerative failure after spinal cord injury, but the molecular mechanisms underlying CSPG expression remain largely undefined. One contributing factor is transforming growth factor β (TGFβ), which is upregulated after injury and has been shown to induce expression of CSPGs in vitro. TGFβ typically mediates its effects through the Smad2/3 signaling pathway, and it has been suggested that this pathway is responsible for CSPG expression. However, there is evidence that TGFβ can also activate non-Smad signaling pathways. In this study, we report that TGFβ-induced expression of three different CSPGs--neurocan, brevican, and aggrecan--is mediated through non-Smad signaling pathways. We observed significant increases in TGFβ-induced expression of neurocan, brevican, and aggrecan following siRNA knockdown of Smad2 or Smad4, which indicates that Smad signaling is not required for the expression of these CSPGs. In addition, we show that neurocan, aggrecan, and brevican levels are significantly reduced when TGFβ is administered in the presence of either the PI3K inhibitor LY294002 or the mTOR inhibitor rapamycin, but not the MEK1/2 inhibitor U0126. This suggests that TGFβ mediates this effect through non-Smad-dependent activation of the PI3K-Akt-mTOR signaling pathway, and targeting this pathway may therefore be an effective means of reducing CSPG expression in the injured CNS. Copyright © 2014 Elsevier Inc. All rights reserved.

Catalytic transformation of persistent contaminants using a new composite material based on nanosized zero-valent metal - field experiment results

NASA Astrophysics Data System (ADS)

Dror, I.; Merom Jacov, O.; Berkowitz, B.

2010-12-01

A new composite material based on deposition of nanosized zero valent iron (ZVI) particles and cyanocobalamine (vitamin B12) on a diatomite matrix is presented. Cyanocobalamine is known to be an effective electron mediator, having strong synergistic effects with ZVI for reductive dehalogenation reactions. This composite material also improves the reducing capacity of nanosized ZVI by preventing agglomeration of iron particles, thus increasing their active surface area. The porous structure of the diatomite matrix allows high hydraulic conductivity, which favors channeling of contaminated water to the reactive surface of the composite material and in turn faster rates of remediation. The ability of the material to degrade or transform rapidly and completely a large spectrum of water pollutants will be demonstrated, based on results from two field site experiments where polluted groundwater containing a mixture of industrial and agricultural persistent pollutants was treated. In addition a set of laboratory experiments using individual contaminant solutions to analyze chemical transformations under controlled conditions will be presented.

Stability of phase transformation models for Ti-6Al-4V under cyclic thermal loading imposed during laser metal deposition

NASA Astrophysics Data System (ADS)

Klusemann, Benjamin; Bambach, Markus

2018-05-01

Processing conditions play a crucial role for the resulting microstructure and properties of the material. In particular, processing materials under non-equilibrium conditions can lead to a remarkable improvement of the final properties [1]. Additive manufacturing represents a specific process example considered in this study. Models for the prediction of residual stresses and microstructure in additive manufacturing processes, such as laser metal deposition, are being developed with huge efforts to support the development of materials and processes as well as to support process design [2-4]. Since the microstructure predicted after each heating and cooling cycle induced by the moving laser source enters the phase transformation kinetics and microstucture evolution of the subsequent heating and cooling cycle, a feed-back loop for the microstructure calculation is created. This calculation loop may become unstable so that the computed microstructure and related properties become very sensitive to small variations in the input parameters, e.g. thermal conductivity. In this paper, a model for phase transformation in Ti-6Al-4V, originally proposed by Charles Murgau et al. [5], is adopted and minimal adjusted concerning the decomposition of the martensite phase are made. This model is subsequently used to study the changes in the predictions of the different phase volume fractions during heating and cooling under the conditions of laser metal deposition with respect to slight variations in the thermal process history.

Phase Transformations and Microstructural Evolution: Part II

DOE PAGES

Clarke, Amy Jean

2015-10-30

The activities of the Phase Transformations Committee of the Materials Processing & Manufacturing Division (MPMD) of The Minerals, Metals & Materials Society (TMS) are oriented toward understanding the fundamental aspects of phase transformations. Emphasis is placed on the thermodynamic driving forces for phase transformations, the kinetics of nucleation and growth, interfacial structures and energies, transformation crystallography, surface reliefs, and, above all, the atomic mechanisms of phase transformations. Phase transformations and microstructural evolution are directly linked to materials processing, properties, and performance. In this issue, aspects of liquid–solid and solid-state phase transformations and microstructural evolution are highlighted. Many papers in thismore » issue are highlighted by this paper, giving a brief summary of what they bring to the scientific community.« less

Evolution of Metallicity in Vanadium Dioxide by Creation of Oxygen Vacancies

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Zuo, Fan; Wan, Chenghao; Dutta, Aveek; Kim, Jongbum; Rensberg, Jura; Nawrodt, Ronny; Park, Helen Hejin; Larrabee, Thomas J.; Guan, Xiaofei; Zhou, You; Prokes, S. M.; Ronning, Carsten; Shalaev, Vladimir M.; Boltasseva, Alexandra; Kats, Mikhail A.; Ramanathan, Shriram

2017-03-01

Tuning of the electronic state of correlated materials is key to their eventual use in advanced electronics and photonics. The prototypical correlated oxide (VO2 ) is insulating at room temperature and transforms to a metallic state when heated to 67 °C (340 K). We report the emergence of a metallic state that is preserved down to 1.8 K by annealing thin films of VO2 at an ultralow oxygen partial pressure (PO2˜10-24 atm ). The films can be reverted back to their original state by annealing in oxygen, and this process can be iterated multiple times. The metallic phase created by oxygen deficiency has a tetragonal rutile structure and contains a large number of oxygen vacancies far beyond the solubility at equilibrium (greater than approximately 50 times). The oxygen starvation reduces the oxidation state of vanadium from V4 + to V3 + and leads to the metallization. The extent of resistance reduction (concurrent with tuning of optical properties) can be controlled by the time-temperature envelope of the annealing conditions since the process is diffusionally driven. This experimental platform, which can extensively tune oxygen vacancies in correlated oxides, provides an approach to study emergent phases and defect-mediated adaptive electronic and structural phase boundary crossovers.

Relationship between expression level of hygromycin B-resistant gene and Agrobacterium tumefaciens-mediated transformation efficiency in Beauveria bassiana JEF-007.

PubMed

Nai, Y S; Lee, M R; Kim, S; Lee, S J; Kim, J C; Yang, Y T; Kim, J S

2017-09-01

Agrobacterium tumefaciens-mediated transformation (AtMT) is an effective method for generation of entomopathogenic Beauveria bassiana transformants. However, some strains grow on the selective medium containing hygromycin B (HygB), which reduces the selection efficiency of the putative transformants. In this work, a relationship between HygB resistance gene promoter and AtMT efficiency was investigated to improve the transformant selection. Ten B. bassiana isolates were grown on 800 μg ml -1 HygB medium, but only JEF-006, -007 and -013 showed susceptibility to the antibiotics. Particularly, JEF-007 showed the most dose-dependent susceptibility. Two different Ti-Plasmids, pCeg (gpdA promoter based) and pCambia-egfp (CaMV 35S promoter based), were constructed to evaluate the promoters on the expression of HygB resistance gene (hph) at 100, 150 and 200 μg ml -1 HygB medium. Eight days after the transformation, wild type, AtMT/pCeg and AtMT/pCambia-egfp colonies were observed on 100 μg ml -1 HygB, but significantly larger numbers of colonies were counted on AtMT/pCeg plates. At higher HygB concentration (150 μg ml -1 ), only AtMT/pCeg colonies were further observed, but very few colonies were observed on the wild type and AtMT/pCambia-egfp plates. Putative transformants were subjected to PCR, RT-PCR and qRT-PCR to investigate the T-DNA insertion rate and gene expression level. Consequently, >80% of colonies showed successful AtMT transformation, and the hph expression level in AtMT/pCeg colonies was higher than that of AtMT/pCambia-egfp colonies. In the HygB-susceptible B. bassianaJEF-007, gpdA promoter works better than CaMV 35S promoter in the expression of HygB resistance gene at 150 μg ml -1 HygB, consequently improving the selection efficiency of putative transformants. These results provide useful information for determining AtMT effectiveness in B. bassiana isolates, particularly antibiotic susceptibility and the role of promoters. © 2017 The

Transforming growth factor beta mediates the progesterone suppression of an epithelial metalloproteinase by adjacent stroma in the human endometrium.

PubMed Central

Bruner, K L; Rodgers, W H; Gold, L I; Korc, M; Hargrove, J T; Matrisian, L M; Osteen, K G

1995-01-01

Unlike most normal adult tissues, cyclic growth and tissue remodeling occur within the uterine endometrium throughout the reproductive years. The matrix metalloproteinases (MMPs), a family of structurally related enzymes that degrade specific components of the extracellular matrix are thought to be the physiologically relevant mediators of extracellular matrix composition and turnover. Our laboratory has identified MMPs of the stromelysin family in the cycling human endometrium, implicating these enzymes in mediating the extensive remodeling that occurs in this tissue. While the stromelysins are expressed in vivo during proliferation-associated remodeling and menstruation-associated endometrial breakdown, none of the stromelysins are expressed during the progesterone-dominated secretory phase of the cycle. Our in vitro studies of isolated cell types have confirmed progesterone suppression of stromal MMPs, but a stromal-derived paracrine factor was found necessary for suppression of the epithelial-specific MMP matrilysin. In this report, we demonstrate that transforming growth factor beta (TGF-beta) is produced by endometrial stroma in response to progesterone and can suppress expression of epithelial matrilysin independent of progesterone. Additionally, we find that an antibody directed against the mammalian isoforms of TGF-beta abolishes progesterone suppression of matrilysin in stromal-epithelial cocultures, implicating TGF-beta as the principal mediator of matrilysin suppression in the human endometrium. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:7638197

High-efficiency Agrobacterium rhizogenes-mediated transformation of heat inducible sHSP18.2-GUS in Nicotiana tabacum.

PubMed

Chen, Shih-Cheng; Liu, Hui-Wen; Lee, Kung-Ta; Yamakawa, Takashi

2007-01-01

The chimerical gene, Arabidopsis thaliana sHSP18.2 promoter fused to E. coli gusA gene, was Agrobacterium rhizogenes-mediated transformed into Nicotiana tabacum as a heat-regulatable model, and the thermo-inducible expression of GUS activity in N. tabacum transgenic hairy roots was profiled. An activation of A. rhizogenes with acetosyringone (AS) before cocultured with tobacco's leaf disc strongly promoted transgenic hairy roots formation. Transgenic hairy roots formation efficiency of A. rhizogenes precultured with 200 microM AS supplementation was 3.1-fold and 7.5-fold, respectively, compared to the formation efficiency obtained with and without AS supplementation in coculture. Transgenic hairy roots transformed with different AS concentration exhibited a similar pattern of thermo-inducibility after 10 min to 3 h heat treatments detected by GUS expression. The peak of expressed GUS specific activity, 399,530 pmol MUG per mg total protein per min, of the transgenic hairy roots was observed at 48 h after 3 h of 42 degrees C heat treatment, and the expressed GUS specific activity was 7-26 times more than that reported in A. thaliana, tobacco BY-2 cells and Nicotiana plumbaginifolia. Interference caused by AS supplementation on the growth of transgenic hairy roots, time-course of GUS expression and its expression level were not observed.

Phyto-mediated metallic nano-architectures via Melissa officinalis L.: synthesis, characterization and biological properties.

PubMed

Fierascu, Irina; Georgiev, Milen I; Ortan, Alina; Fierascu, Radu Claudiu; Avramescu, Sorin Marius; Ionescu, Daniela; Sutan, Anca; Brinzan, Alexandru; Ditu, Lia Mara

2017-09-29

The development of methods for obtaining new materials with antimicrobial properties, based on green chemistry principles has been a target of research over the past few years. The present paper describes the phyto-mediated synthesis of metallic nano-architectures (gold and silver) via an ethanolic extract of Melissa officinalis L. (obtained by accelerated solvent extraction). Different analytic methods were applied for the evaluation of the extract composition, as well as for the characterization of the phyto-synthesized materials. The cytogenotoxicity of the synthesized materials was evaluated by Allium cepa assay, while the antimicrobial activity was examined by applying both qualitative and quantitative methods. The results demonstrate the synthesis of silver nanoparticles (average diameter 13 nm) and gold nanoparticles (diameter of ca. 10 nm); the bi-metallic nanoparticles proved to have a core-shell flower-like structure, composed of smaller particles (ca. 8 nm). The Ag nanoparticles were found not active on nuclear DNA damage. The Au nanoparticles appeared nucleoprotective, but were aggressive in generating clastogenic aberrations in A. cepa root meristematic cells. Results of the antimicrobial assays show that silver nanoparticles were active against most of the tested strains, as the lowest MIC value being obtained against B. cereus (approx. 0.0015 mM).

Intracellular mediators of transforming growth factor beta superfamily signaling localize to endosomes in chicken embryo and mouse lenses in vivo.

PubMed

Rajagopal, Ramya; Ishii, Shunsuke; Beebe, David C

2007-06-25

Endocytosis is a key regulator of growth factor signaling pathways. Recent studies showed that the localization to endosomes of intracellular mediators of growth factor signaling may be required for their function. Although there is substantial evidence linking endocytosis and growth factor signaling in cultured cells, there has been little study of the endosomal localization of signaling components in intact tissues or organs. Proteins that are downstream of the transforming growth factor-beta superfamily signaling pathway were found on endosomes in chicken embryo and postnatal mouse lenses, which depend on signaling by members of the TGFbeta superfamily for their normal development. Phosphorylated Smad1 (pSmad1), pSmad2, Smad4, Smad7, the transcriptional repressors c-Ski and TGIF and the adapter molecules Smad anchor for receptor activation (SARA) and C184M, localized to EEA-1- and Rab5-positive vesicles in chicken embryo and/or postnatal mouse lenses. pSmad1 and pSmad2 also localized to Rab7-positive late endosomes. Smad7 was found associated with endosomes, but not caveolae. Bmpr1a conditional knock-out lenses showed decreased nuclear and endosomal localization of pSmad1. Many of the effectors in this pathway were distributed differently in vivo from their reported distribution in cultured cells. Based on the findings reported here and data from other signaling systems, we suggest that the localization of activated intracellular mediators of the transforming growth factor-beta superfamily to endosomes is important for the regulation of growth factor signaling.

Effect of ferrite transformation on the tensile and stress corrosion properties of type 316 L stainless steel weld metal thermally aged at 873 K

NASA Astrophysics Data System (ADS)

Shaikh, H.; Khatak, H. S.; Seshadri, S. K.; Gnanamoorthy, J. B.; Rodriguez, P.

1995-07-01

This article deals with the effect of the microstructural changes, due to transformation of delta ferrite, on the associated variations that take place in the tensile and stress corrosion properties of type 316 L stainless steel weld deposits when subjected to postweld heat treatment at 873 K for prolonged periods (up to 2000 hours). On aging for short durations (up to 20 hours), carbide/ carbonitride was the dominant transformation product, whereas sigma phase was dominant at longer aging times. The changes in the tensile and stress corrosion behavior of the aged weld metal have been attributed to the two competitive processes of matrix softening and hardening. Yield strength (YS) was found to depend predominantly on matrix softening only, while sig-nificant changes in the ultimate tensile strength (UTS) and the work-hardening exponent, n, occurred due to matrix hardening. Ductility and stress corrosion properties were considerably affected by both factors. Fractographic observations on the weld metal tested for stress-corrosion cracking (SCC) indicated a combination of transgranular cracking of the austenite and interface cracking.

Water-mediated solid-state transformation of a polymorphic drug during aqueous-based drug-layer coating of pellets.

PubMed

Lust, Andres; Lakio, Satu; Vintsevits, Julia; Kozlova, Jekaterina; Veski, Peep; Heinämäki, Jyrki; Kogermann, Karin

2013-11-01

During aqueous drug-layer coating, drug substance(s) are exposed to water and elevated temperatures which can lead to water-mediated process induced transformations (PITs). The effects of aqueous drug-layer coating of pellets (Cellets(®)) on the anhydrous piroxicam, PRX, were investigated in the miniaturized coating equipment and with free films. Hydroxypropyl methylcellulose (HPMC) was used as a carrier coating polymer. Free films were prepared by using an in-house small-scale rotating plate system equipped with an atomization air nozzle. Raman spectroscopy, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the solid-state properties and surface morphology of the pellets and free films. The results showed that anhydrous PRX form I (AH) and monohydrate (MH) were stable during drug-layer coating, but amorphous PRX in solid dispersion (SD) crystallized as MH already after 10 min of coating. Furthermore, the increase in a dissolution rate was achieved from the drug-layer coated inert pellets compared to powder forms. In conclusion, water-mediated solid-state PITs of amorphous PRX is evident during aqueous-based drug-layer coating of pellets, and solid-state change can be verified using Raman spectroscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

Germline Transformation of Drosophila Virilis Mediated by the Transposable Element Hobo

PubMed Central

Lozovskaya, E. R.; Nurminsky, D. I.; Hartl, D. L.; Sullivan, D. T.

1996-01-01

A laboratory strain of Drosophila virilis was genetically transformed with a hobo vector carrying the miniwhite cassette using a helper plasmid with an hsp70-driven hobo transposase-coding sequence. The rate of transformation was 0.5% per fertile G0 animal. Three transgenic insertions were cloned and characterized and found to be authentic hobo insertions. These results, together with the known wide-spread distribution of hobo in diverse insect species, suggest that hobo and related transposable elements may be of considerable utility in the germline transformation of insects other than D. melanogaster. PMID:8770594

Leiomyoma-derived transforming growth factor-β impairs bone morphogenetic protein-2-mediated endometrial receptivity.

PubMed

Doherty, Leo F; Taylor, Hugh S

2015-03-01

To determine whether transforming growth factor (TGF)-β3 is a paracrine signal secreted by leiomyoma that inhibits bone morphogenetic protein (BMP)-mediated endometrial receptivity and decidualization. Experimental. Laboratory. Women with symptomatic leiomyomas. Endometrial stromal cells (ESCs) and leiomyoma cells were isolated from surgical specimens. Leiomyoma-conditioned media (LCM) was applied to cultured ESC. The TGF-β was blocked by two approaches: TGF-β pan-specific antibody or transfection with a mutant TGF-β receptor type II. Cells were then treated with recombinant human BMP-2 to assess BMP responsiveness. Expression of BMP receptor types 1A, 1B, 2, as well as endometrial receptivity mediators HOXA10 and leukemia inhibitory factor (LIF). Enzyme-linked immunosorbent assay showed elevated TGF-β levels in LCM. LCM treatment of ESC reduced expression of BMP receptor types 1B and 2 to approximately 60% of pretreatment levels. Preincubation of LCM with TGF-β neutralizing antibody or mutant TGF receptor, but not respective controls, prevented repression of BMP receptors. HOXA10 and LIF expression was repressed in recombinant human BMP-2 treated, LCM exposed ESC. Pretreatment of LCM with TGF-β antibody or transfection with mutant TGF receptor prevented HOXA10 and LIF repression. Leiomyoma-derived TGF-β was necessary and sufficient to alter endometrial BMP-2 responsiveness. Blockade of TGF-β prevents repression of BMP-2 receptors and restores BMP-2-stimulated expression of HOXA10 and LIF. Blockade of TGF signaling is a potential strategy to improve infertility and pregnancy loss associated with uterine leiomyoma. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Macromolecular metal carboxylates

NASA Astrophysics Data System (ADS)

Dzhardimalieva, G. I.; Pomogailo, A. D.

2008-03-01

Data on the synthesis and physicochemical studies of salts of mono- or dibasic unsaturated carboxylic acids and unsaturated metal oxo-carboxylates are generalised and described systematically. The structures and properties of the COO group in various compounds and characteristic features of the structures of carboxylate complexes are analysed. The main routes and kinetics of polymerisation transformations of unsaturated metal carboxylates are considered. The attention is focused on the effect of the metal ion on the monomer reactivity and the polymer morphology and structure. The possibility of stereochemical control of radical polymerisation of unsaturated metal carboxylates is demonstrated. The electronic, magnetic, optical, absorption and thermal properties of metal (co)polymers and nanocomposites and their main applications are considered.

Transforming Ourselves through the Power of Mediated Instruction.

ERIC Educational Resources Information Center

Guadarrama, Irma N., Ed.; Kirksey, Lockie, Ed.

1996-01-01

A collection of essays on English-as-a-Second-Language (ESL) and bilingual education focuses on issues in making curricula meaningful for teachers and students. Articles include: "Critical Mediation: When Teachers and Students Connect in the 'Ecliptic Zone'" (Irma N. Guadarrama); "Reflecting on Ideological Baggage: Latino…

Barriers to horizontal cell transformation by extracellular vesicles containing oncogenic H-ras.

PubMed

Lee, Tae Hoon; Chennakrishnaiah, Shilpa; Meehan, Brian; Montermini, Laura; Garnier, Delphine; D'Asti, Esterina; Hou, Wenyang; Magnus, Nathalie; Gayden, Tenzin; Jabado, Nada; Eppert, Kolja; Majewska, Loydie; Rak, Janusz

2016-08-09

Extracellular vesicles (EVs) enable the exit of regulatory, mutant and oncogenic macromolecules (proteins, RNA and DNA) from their parental tumor cells and uptake of this material by unrelated cellular populations. Among the resulting biological effects of interest is the notion that cancer-derived EVs may mediate horizontal transformation of normal cells through transfer of mutant genes, including mutant ras. Here, we report that H-ras-mediated transformation of intestinal epithelial cells (IEC-18) results in the emission of exosome-like EVs containing genomic DNA, HRAS oncoprotein and transcript. However, EV-mediated horizontal transformation of non-transformed cells (epithelial, astrocytic, fibroblastic and endothelial) is transient, limited or absent due to barrier mechanisms that curtail the uptake, retention and function of oncogenic H-ras in recipient cells. Thus, epithelial cells and astrocytes are resistant to EV uptake, unless they undergo malignant transformation. In contrast, primary and immortalized fibroblasts are susceptible to the EV uptake, retention of H-ras DNA and phenotypic transformation, but these effects are transient and fail to produce a permanent tumorigenic conversion of these cells in vitro and in vivo, even after several months of observation. Increased exposure to EVs isolated from H-ras-transformed cancer cells, but not to those from their indolent counterparts, triggers demise of recipient fibroblasts. Uptake of H-ras-containing EVs stimulates but fails to transform primary endothelial cells. Thus, we suggest that intercellular transfer of oncogenes exerts regulatory rather than transforming influence on recipient cells, while cancer cells may often act as preferential EV recipients.

Barriers to horizontal cell transformation by extracellular vesicles containing oncogenic H-ras

PubMed Central

Lee, Tae Hoon; Chennakrishnaiah, Shilpa; Meehan, Brian; Montermini, Laura; Garnier, Delphine; D'Asti, Esterina; Hou, Wenyang; Magnus, Nathalie; Gayden, Tenzin; Jabado, Nada; Eppert, Kolja; Majewska, Loydie; Rak, Janusz

2016-01-01

Extracellular vesicles (EVs) enable the exit of regulatory, mutant and oncogenic macromolecules (proteins, RNA and DNA) from their parental tumor cells and uptake of this material by unrelated cellular populations. Among the resulting biological effects of interest is the notion that cancer-derived EVs may mediate horizontal transformation of normal cells through transfer of mutant genes, including mutant ras. Here, we report that H-ras-mediated transformation of intestinal epithelial cells (IEC-18) results in the emission of exosome-like EVs containing genomic DNA, HRAS oncoprotein and transcript. However, EV-mediated horizontal transformation of non-transformed cells (epithelial, astrocytic, fibroblastic and endothelial) is transient, limited or absent due to barrier mechanisms that curtail the uptake, retention and function of oncogenic H-ras in recipient cells. Thus, epithelial cells and astrocytes are resistant to EV uptake, unless they undergo malignant transformation. In contrast, primary and immortalized fibroblasts are susceptible to the EV uptake, retention of H-ras DNA and phenotypic transformation, but these effects are transient and fail to produce a permanent tumorigenic conversion of these cells in vitro and in vivo, even after several months of observation. Increased exposure to EVs isolated from H-ras-transformed cancer cells, but not to those from their indolent counterparts, triggers demise of recipient fibroblasts. Uptake of H-ras-containing EVs stimulates but fails to transform primary endothelial cells. Thus, we suggest that intercellular transfer of oncogenes exerts regulatory rather than transforming influence on recipient cells, while cancer cells may often act as preferential EV recipients. PMID:27437771

Joining of parts via magnetic heating of metal aluminum powders

DOEpatents

Baker, Ian

2013-05-21

A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

Rapid limit tests for metal impurities in pharmaceutical materials by X-ray fluorescence spectroscopy using wavelet transform filtering.

PubMed

Arzhantsev, Sergey; Li, Xiang; Kauffman, John F

2011-02-01

We introduce a new method for analysis of X-ray fluorescence (XRF) spectra based on continuous wavelet transform filters, and the method is applied to the determination of toxic metals in pharmaceutical materials using hand-held XRF spectrometers. The method uses the continuous wavelet transform to filter the signal and noise components of the spectrum. We present a limit test that compares the wavelet domain signal-to-noise ratios at the energies of the elements of interest to an empirically determined signal-to-noise decision threshold. The limit test is advantageous because it does not require the user to measure calibration samples prior to measurement, though system suitability tests are still recommended. The limit test was evaluated in a collaborative study that involved five different hand-held XRF spectrometers used by multiple analysts in six separate laboratories across the United States. In total, more than 1200 measurements were performed. The detection limits estimated for arsenic, lead, mercury, and chromium were 8, 14, 20, and 150 μg/g, respectively.

The Role of Transforming Growth Factor β in Cell-to-Cell Contact-Mediated Epstein-Barr Virus Transmission.

PubMed

Nanbo, Asuka; Ohashi, Makoto; Yoshiyama, Hironori; Ohba, Yusuke

2018-01-01

Infection of Epstein-Barr virus (EBV), a ubiquitous human gamma herpesvirus, is closely linked to various lymphoid and epithelial malignancies. Previous studies demonstrated that the efficiency of EBV infection in epithelial cells is significantly enhanced by coculturing them with latently infected B cells relative to cell-free infection, suggesting that cell-to-cell contact-mediated viral transmission is the dominant mode of infection by EBV in epithelial cells. However, a detailed mechanism underlying this process has not been fully understood. In the present study, we assessed the role of transforming growth factor β (TGF-β), which is known to induce EBV's lytic cycle by upregulation of EBV's latent-lytic switch BZLF1 gene. We have found that 5 days of cocultivation facilitated cell-to-cell contact-mediated EBV transmission. Replication of EBV was induced in cocultured B cells both with and without a direct cell contact in a time-dependent manner. Treatment of a blocking antibody for TGF-β suppressed both induction of the lytic cycle in cocultured B cells and subsequent viral transmission. Cocultivation with epithelial cells facilitated expression of TGF-β receptors in B cells and increased their susceptibility to TGF-β. Finally, we confirmed the spontaneous secretion of TGF-β from epithelial cells, which was not affected by cell-contact. In contrast, the extracellular microvesicles, exosomes derived from cocultured cells partly contributed to cell-to-cell contact-mediated viral transmission. Taken together, our findings support a role for TGF-β derived from epithelial cells in efficient viral transmission, which fosters induction of the viral lytic cycle in the donor B cells.

Bioleaching combined brine leaching of heavy metals from lead-zinc mine tailings: Transformations during the leaching process.

PubMed

Ye, Maoyou; Yan, Pingfang; Sun, Shuiyu; Han, Dajian; Xiao, Xiao; Zheng, Li; Huang, Shaosong; Chen, Yun; Zhuang, Shengwei

2017-02-01

During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simple-to-Complex Transformation in Liquid Rubidium.

PubMed

Gorelli, Federico A; De Panfilis, Simone; Bryk, Taras; Ulivi, Lorenzo; Garbarino, Gaston; Parisiades, Paraskevas; Santoro, Mario

2018-05-18

We investigated the atomic structure of liquid Rb along an isothermal path at 573 K, up to 23 GPa, by X-ray diffraction measurements. By raising the pressure, we observed a liquid-liquid transformation from a simple metallic liquid to a complex one. The transition occurs at 7.5 ± 1 GPa which is slightly above the first maximum of the T-P melting line. This transformation is traced back to the density-induced hybridization of highest electronic orbitals leading to the accumulation of valence electrons between Rb atoms and to the formation of interstitial atomic shells, a behavior that Rb shares with Cs and is likely to be common to all alkali metals.

Causal Mediation Analysis of Survival Outcome with Multiple Mediators.

PubMed

Huang, Yen-Tsung; Yang, Hwai-I

2017-05-01

Mediation analyses have been a popular approach to investigate the effect of an exposure on an outcome through a mediator. Mediation models with multiple mediators have been proposed for continuous and dichotomous outcomes. However, development of multimediator models for survival outcomes is still limited. We present methods for multimediator analyses using three survival models: Aalen additive hazard models, Cox proportional hazard models, and semiparametric probit models. Effects through mediators can be characterized by path-specific effects, for which definitions and identifiability assumptions are provided. We derive closed-form expressions for path-specific effects for the three models, which are intuitively interpreted using a causal diagram. Mediation analyses using Cox models under the rare-outcome assumption and Aalen additive hazard models consider effects on log hazard ratio and hazard difference, respectively; analyses using semiparametric probit models consider effects on difference in transformed survival time and survival probability. The three models were applied to a hepatitis study where we investigated effects of hepatitis C on liver cancer incidence mediated through baseline and/or follow-up hepatitis B viral load. The three methods show consistent results on respective effect scales, which suggest an adverse estimated effect of hepatitis C on liver cancer not mediated through hepatitis B, and a protective estimated effect mediated through the baseline (and possibly follow-up) of hepatitis B viral load. Causal mediation analyses of survival outcome with multiple mediators are developed for additive hazard and proportional hazard and probit models with utility demonstrated in a hepatitis study.

Metal ions induced heat shock protein response by elevating superoxide anion level in HeLa cells transformed by HSE-SEAP reporter gene.

PubMed

Yu, Zhanjiang; Yang, Xiaoda; Wang, Kui

2006-06-01

The aim of this work is to define the relationship between heat shock protein (HSP) and reactive oxygen species (ROS) in the cells exposed to different concentrations of metal ions, and to evaluate a new method for tracing the dynamic levels of cellular reactive oxygen species using a HSE-SEAP reporter gene. The expression of heat shock protein was measured using a secreted alkaline phosphatase (SEAP) reporter gene transformed into HeLa cell strain, the levels of superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)) were determined by NBT reduction assay and DCFH staining flow cytometry (FCM), respectively. The experimental results demonstrated that the expression of heat shock protein induced by metal ions was linearly related to the cellular superoxide anion level before cytotoxic effects were observed, but not related to the cellular hydrogen peroxide level. The experimental results suggested that metal ions might induce heat shock protein by elevating cellular superoxide anion level, and thus the expression of heat shock protein indicated by the HSE-SEAP reporter gene can be an effective model for monitoring the dynamic level of superoxide anion and early metal-induced oxidative stress/cytotoxicity.

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

NASA Astrophysics Data System (ADS)

Song, Zhibo; Wang, Qixing; Li, Ming-Yang; Li, Lain-Jong; Zheng, Yu Jie; Wang, Zhuo; Lin, Tingting; Chi, Dongzhi; Ding, Zijing; Huang, Yu Li; Thye Shen Wee, Andrew

2018-04-01

Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48 ) on single-layer tungsten diselenide (WSe2) is revealed by low-temperature scanning tunneling microscopy, from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers insights into the growth behavior at 2D organic/TMD hybrid heterointerfaces.

ENVIRONMENTAL CHARACTERISTICS AFFECTING REDUCTIVE TRANSFORMATION OF ORGANIC POLLUTANTS IN ANOXIC SEDIMENTS

EPA Science Inventory

Reductive transformations are important processes for determining the fate of organic pollutants in anoxic environments. These processes are most often microbially mediated by both direct and indirect means. For example, specific bacteria transform organic pollutants directly as ...

Mediated electrochemical oxidation of organic wastes without electrode separators

DOEpatents

Farmer, Joseph C.; Wang, Francis T.; Hickman, Robert G.; Lewis, Patricia R.

1996-01-01

An electrochemical cell/electrolyte/mediator combination for the efficient destruction of organic contaminants using metal salt mediators in a sulfuric acid electrolyte, wherein the electrodes and mediator are chosen such that hydrogen gas is produced at the cathode and no cell membrane is required.

Exploring the impact of transformational leadership on nurse innovation behaviour: a cross-sectional study.

PubMed

Weng, Rhay-Hung; Huang, Ching-Yuan; Chen, Li-Mei; Chang, Li-Yu

2015-05-01

This study explored the influences of transformational leadership on nurse innovation behaviour and the mediating role of organisational climate. Recently, global nursing experts have been aggressively encouraging nurses to pursue innovation in nursing in order to improve nursing outcomes. Nursing innovation, in turn, is affected by nursing leadership. We employed a questionnaire survey to collect data, and selected a sample of nurses from hospitals in Taiwan. A total of 439 valid surveys were obtained. Hierarchical multiple regression model analysis was conducted to test the study hypothesis. The mean values of agreement of nurse innovation behaviour and transformational leadership were 3.40 and 3.78, respectively. Patient safety climate and innovation climate were found to have full mediating effects on the relationship between transformational leadership and innovation behaviour. Organisational climate has a significant impact on innovation behaviour. Transformational leadership has indirect effects on innovation behaviour via the mediation of patient safety climate and innovation climate. Hospitals should enhance transformational leadership by designing leadership training programmes and establishing transformational culture. In addition, nursing managers should foster nursing innovation through improvements in organisational climate. © 2013 John Wiley & Sons Ltd.

Ectopic Integration of Transforming DNA Is Rare among Neurospora Transformants Selected for Gene Replacement

PubMed Central

Miao, VPW.; Rountree, M. R.; Selker, E. U.

1995-01-01

In a variety of organisms, DNA-mediated transformation experiments commonly produce transformants with multiple copies of the transforming DNA, including both selected and unselected molecules. Such ``cotransformants'' are much more common than expected from the individual transformation frequencies, suggesting that subpopulations of cells, or nuclei, are particularly competent for transformation. We found that Neurospora crassa transformants selected for gene replacement at the am gene had not efficiently incorporated additional DNA, suggesting that nuclei that undergo transformation by homologous recombination are not highly competent at integration of DNA by illegitimate recombination. Spheroplasts were treated with DNA fragments homologous to am and with an Escherichia coli hph plasmid. Transformants were initially selected for hph (hygromycin(R)), allowed to conidiate to generate homokaryons and then selected for either Am(-) (gene replacements) or hph. Surprisingly, most am replacement strains were hygromycin(S) (124/140) and carried no extraneous DNA (116/140). Most transformants selected for hph also had ectopic copies of am DNA and/or multiple copies of hph sequences (32/35), generally at multiple sites, confirming that efficient cotransformation could occur. To test the implication that cotransformation involving gene replacement and ectopic integration is rare, we compared the yields of am replacement strains with or without prior selection for hph. The initial selection did not appreciably help (or hinder) recovery of strains with replacements. PMID:7789758

Isolation of a conjugative F-like plasmid from a multidrug-resistant Escherichia coli strain CM6 using tandem shock wave-mediated transformation.

PubMed

Soto-Alonso, G; Cruz-Medina, J A; Caballero-Pérez, J; Arvizu-Hernández, I; Ávalos-Esparza, L M; Cruz-Hernández, A; Romero-Gómez, S; Rodríguez, A L; Pastrana-Martínez, X; Fernández, F; Loske, A M; Campos-Guillén, J

2015-07-01

Genetic characterization of plasmids from bacterial strains provides insight about multidrug resistance. Ten wild type Escherichia coli (E. coli) strains isolated from cow fecal samples were characterized by their antibiotic resistance profile, plasmid patterns and three different identification methods. From one of the strains, a fertility factor-like plasmid was replicated using tandem shock wave-mediated transformation. Underwater shock waves with a positive pressure peak of up to approximately 40 MPa, followed by a pressure trough of approximately -19 MPa were generated using an experimental piezoelectric shock wave source. Three different shock wave energies and a fixed delay of 750 μs were used to study the relationship between energy and transformation efficiency (TE), as well as the influence of shock wave energy on the integrity of the plasmid. Our results showed that the mean shock wave-mediated TE and the integrity of the large plasmid (~70 kb) were reduced significantly at the energy levels tested. The sequencing analysis of the plasmid revealed a high identity to the pHK17a plasmid, including the replication system, which was similar to the plasmid incompatibility group FII. It also showed that it carried an extended spectrum beta-lactamase gene, ctx-m-14. Furthermore, diverse genes for the conjugative mechanism were identified. Our results may be helpful in improving methodologies for conjugative plasmid transfer and directly selecting the most interesting plasmids from environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Transforming Environmental Knowledge into Behavior: The Mediating Role of Environmental Emotions

ERIC Educational Resources Information Center

Carmi, Nurit; Arnon, Sara; Orion, Nir

2015-01-01

The present study was based on the premise that environmental knowledge can drive environmental behavior only if it arouses environmental emotions. Using a structural equations modeling approach, we tested the direct, as well as the indirect (mediated) effects of knowledge on behavior and assessed the mediating role of environmental emotions. We…

Mexican immigrant transnational social capital and class transformation: examining the role of peer mediation in insurgent science

NASA Astrophysics Data System (ADS)

Richardson Bruna, Katherine

2010-06-01

In this article, I return to the interactions of Augusto and his teacher in an "English Learner Science" classroom in a demographically-transitioning US Midwest community (Richardson Bruna and Vann in Cult Stud Sci Educ 2:19-59, 2007) and further engage a class-first perspective to achieve two main conceptual objectives. First, I examine Augusto's science education experience as a way of understanding processes Rouse (Towards a transnational perspective on migration: Race, class, ethnicity, and nationalism reconsidered. The New York Academy of Sciences, New York, 1992) refers to as "the disciplinary production of class-specific subjects" (p. 31). Coming from a subsistence farming community in rural Mexico to an industrialized meatpacking community in semi-rural Iowa, I describe how Augusto undergoes a change in his class identity (experiences a Class Transformation) that is not just reflected but, in fact, produced in his science class. Second, I examine the work Augusto does to resist these processes of disciplinary production as he reshapes his teacher's instruction (promotes a class transformation) through specific transnational social capital he leverages as peer mediation. My overall goals in the article are to demonstrate the immediate relevance of a socio-historical, situated perspective to science teaching and learning and to outline domains of action for an insurgent, class-cognizant, science education practice informed by transnational social capital, like Augusto's.

The kinases MEKK2 and MEKK3 regulate transforming growth factor-β-mediated helper T cell differentiation.

PubMed

Chang, Xing; Liu, Fang; Wang, Xiaofang; Lin, Aiping; Zhao, Hongyu; Su, Bing

2011-02-25

Mitogen-activated protein kinases (MAPKs) are key mediators of the T cell receptor (TCR) signals but their roles in T helper (Th) cell differentiation are unclear. Here we showed that the MAPK kinase kinases MEKK2 (encoded by Map3k2) and MEKK3 (encoded by Map3k3) negatively regulated transforming growth factor-β (TGF-β)-mediated Th cell differentiation. Map3k2(-/-)Map3k3(Lck-Cre/-) mice showed an abnormal accumulation of regulatory T (Treg) and Th17 cells in the periphery, consistent with Map3k2(-/-)Map3k3(Lck-Cre/-) naive CD4(+) T cells' differentiation into Treg and Th17 cells with a higher frequency than wild-type (WT) cells after TGF-β stimulation in vitro. In addition, Map3k2(-/-)Map3k3(Lck-Cre/-) mice developed more severe experimental autoimmune encephalomyelitis. Map3k2(-/-)Map3k3(Lck-Cre/-) T cells exhibited impaired phosphorylation of SMAD2 and SMAD3 proteins at their linker regions, which negatively regulated the TGF-β responses in T cells. Thus, the crosstalk between TCR-induced MAPK and the TGF-β signaling pathways is important in regulating Th cell differentiation. Copyright © 2011 Elsevier Inc. All rights reserved.

Transforming growth factor beta induced FoxP3+ regulatory T cells suppress Th1 mediated experimental colitis.

PubMed

Fantini, M C; Becker, C; Tubbe, I; Nikolaev, A; Lehr, H A; Galle, P; Neurath, M F

2006-05-01

The imbalance between effector and regulatory T cells plays a central role in the pathogenesis of inflammatory bowel diseases. In addition to the thymus, CD4+CD25+ regulatory T cells can be induced in the periphery from a population of CD25- T cells by treatment with transforming growth factor beta (TGF-beta). Here, we analysed the in vivo function of TGF-beta induced regulatory T (Ti-Treg) cells in experimental colitis. Ti-Treg cells were generated in cell culture in the presence or absence of TGF-beta and tested for their regulatory potential in experimental colitis using the CD4+CD62L+ T cell transfer model. Ti-Treg cells significantly suppressed Th1 mediated colitis on CD4+CD62L+ T cell transfer in vivo, as shown by high resolution endoscopy, histology, immunohistochemistry, and cytokine analysis. Further analysis of in vivo and in vitro expanded Ti-Treg cells showed that exogenous interleukin 2 (IL-2) was crucial for survival and expansion of these cells. Our data suggest that regulatory Ti-Treg cells expand by TGF-beta and exogenous IL-2 derived from effector T cells at the site of inflammation. In addition to Tr1 and thymic CD4+CD25+ T cells, peripheral Ti-Treg cells emerge as a class of regulatory T cells with therapeutic potential in T cell mediated chronic intestinal inflammation.

Mediated electrochemical oxidation of organic wastes without electrode separators

DOEpatents

Farmer, J.C.; Wang, F.T.; Hickman, R.G.; Lewis, P.R.

1996-05-14

An electrochemical cell/electrolyte/mediator combination is described for the efficient destruction of organic contaminants using metal salt mediators in a sulfuric acid electrolyte, wherein the electrodes and mediator are chosen such that hydrogen gas is produced at the cathode and no cell membrane is required. 3 figs.

Metal Ions, Not Metal-Catalyzed Oxidative Stress, Cause Clay Leachate Antibacterial Activity

PubMed Central

Otto, Caitlin C.; Koehl, Jennifer L.; Solanky, Dipesh; Haydel, Shelley E.

2014-01-01

Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4–5), generate reactive oxygen species (ROS) and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions. PMID:25502790

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining.

PubMed

Zhang, Xu; Yang, Huanhuan; Cui, Zhaojie

2017-10-01

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.

The construction and use of versatile binary vectors carrying pyrG auxotrophic marker and fluorescent reporter genes for Agrobacterium-mediated transformation of Aspergillus oryzae.

PubMed

Nguyen, Khuyen Thi; Ho, Quynh Ngoc; Pham, Thu Ha; Phan, Tuan-Nghia; Tran, Van-Tuan

2016-12-01

Aspergillus oryzae is a safe mold widely used in food industry. It is also considered as a microbial cell factory for production of recombinant proteins and enzymes. Currently, genetic manipulation of filamentous fungi is achieved via Agrobacterium tumefaciens-mediated transformation methods usually employing antibiotic resistance markers. These methods are hardly usable for A. oryzae due to its strong resistance to the common antifungal compounds used for fungal transformation. In this study, we have constructed two binary vectors carrying the pyrG gene from A. oryzae as a biochemical marker than an antibiotic resistance marker, and an expression cassette for GFP or DsRed reporter gene under control of the constitutive gpdA promoter from Aspergillus nidulans. All components of these vectors are changeable to generate new versions for specific research purposes. The developed vectors are fully functional for heterologous expression of the GFP and DsRed fluorescent proteins in the uridine/uracil auxotrophic A. oryzae strain. Our study provides a new approach for A. oryzae transformation using pyrG as the selectable auxotrophic marker, A. tumefaciens as the DNA transfer tool and fungal spores as the transformation material. The binary vectors constructed can be used for gene expression studies in this industrially important filamentous fungus.

Phase transformation in tantalum under extreme laser deformation

DOE PAGES

Lu, C. -H.; Hahn, E. N.; Remington, B. A.; ...

2015-10-19

The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centeredmore » cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).« less

Phase Transformation in Tantalum under Extreme Laser Deformation

PubMed Central

Lu, C.-H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

2015-01-01

The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear). PMID:26478106

Chemotherapeutic Drug Based Metal-Organic Particles for Microvesicle-Mediated Deep Penetration and Programmable pH/NIR/Hypoxia Activated Cancer Photochemotherapy.

PubMed

Zhang, Da; Wu, Ming; Cai, Zhixiong; Liao, Naishun; Ke, Kun; Liu, Hongzhi; Li, Ming; Liu, Gang; Yang, Huanghao; Liu, Xiaolong; Liu, Jingfeng

2018-02-01

A novel metal-organic particle (MOP) based nanodrug formed by mild self-assembly of chemotherapeutic drugs, including banoxantrone and doxorubicin, through Cu(II)-mediated coordination effects, is reported. In this nanodrug, Cu(II) acts as a bridge to join AQ4N and DOX, and then, self-assembly of [-AQ4N-Cu(II)-(DOX) 2 -Cu(II)-] n complexes forms nanosized MOPs (referred to as ADMOPs) through multiple interactions including host-metal-guest coordination, hydrophobic interactions, π-stacking, and van der Waals force. The ADMOPs reported here have several important features over conventional drugs, including tumor microenvironment pH-sensitive drug release that can be tracked by "turning on" the fluorescence of AQ4N or DOX through proton competition with Cu(II) to break the coordination bonds and much deeper penetration into solid tumors via microvesicle-mediated intercellular transfer. Most strikingly, the ADMOPs can serve as stimuli-responsive nanocarriers to efficiently load the photosensitizer phthalocyanine due to their inherent highly porous characteristics. Thus, the ADMOPs significantly enhance the chemotherapeutic efficacy by "on-demand" photodynamic therapy, which further induces a hypoxic environment that enhances the reduction of AQ4N to systematically increase the therapeutic efficiency. Taken together, the designed ADMOPs composed of chemotherapeutic drugs may serve as a potential programmable controlled synergistic agent for cancer therapy.

Identification of auxotrophic mutants of the yeast Kluyveromyces marxianus by non-homologous end joining-mediated integrative transformation with genes from Saccharomyces cerevisiae.

PubMed

Yarimizu, Tohru; Nonklang, Sanom; Nakamura, Junpei; Tokuda, Shuya; Nakagawa, Takaaki; Lorreungsil, Sasithorn; Sutthikhumpha, Surasit; Pukahuta, Charida; Kitagawa, Takao; Nakamura, Mikiko; Cha-Aim, Kamonchai; Limtong, Savitree; Hoshida, Hisashi; Akada, Rinji

2013-12-01

The isolation and application of auxotrophic mutants for gene manipulations, such as genetic transformation, mating selection and tetrad analysis, form the basis of yeast genetics. For the development of these genetic methods in the thermotolerant fermentative yeast Kluyveromyces marxianus, we isolated a series of auxotrophic mutants with defects in amino acid or nucleic acid metabolism. To identify the mutated genes, linear DNA fragments of nutrient biosynthetic pathway genes were amplified from Saccharomyces cerevisiae chromosomal DNA and used to directly transform the K. marxianus auxotrophic mutants by random integration into chromosomes through non-homologous end joining (NHEJ). The appearance of transformant colonies indicated that the specific S. cerevisiae gene complemented the K. marxianus mutant. Using this interspecific complementation approach with linear PCR-amplified DNA, we identified auxotrophic mutations of ADE2, ADE5,7, ADE6, HIS2, HIS3, HIS4, HIS5, HIS6, HIS7, LYS1, LYS2, LYS4, LYS9, LEU1, LEU2, MET2, MET6, MET17, TRP3, TRP4 and TRP5 without the labour-intensive requirement of plasmid construction. Mating, sporulation and tetrad analysis techniques for K. marxianus were also established. With the identified auxotrophic mutant strains and S. cerevisiae genes as selective markers, NHEJ-mediated integrative transformation with PCR-amplified DNA is an attractive system for facilitating genetic analyses in the yeast K. marxianus. Copyright © 2013 John Wiley & Sons, Ltd.

Process for the enhanced capture of heavy metal emissions

DOEpatents

Biswas, Pratim; Wu, Chang-Yu

2001-01-01

This invention is directed to a process for forming a sorbent-metal complex. The process includes oxidizing a sorbent precursor and contacting the sorbent precursor with a metallic species. The process further includes chemically reacting the sorbent precursor and the metallic species, thereby forming a sorbent-metal complex. In one particular aspect of the invention, at least a portion of the sorbent precursor is transformed into sorbent particles during the oxidation step. These sorbent particles then are contacted with the metallic species and chemically reacted with the metallic species, thereby forming a sorbent-metal complex. Another aspect of the invention is directed to a process for forming a sorbent metal complex in a combustion system. The process includes introducing a sorbent precursor into a combustion system and subjecting the sorbent precursor to an elevated temperature sufficient to oxidize the sorbent precursor and transform the sorbent precursor into sorbent particles. The process further includes contacting the sorbent particles with a metallic species and exposing the sorbent particles and the metallic species to a complex-forming temperature whereby the metallic species reacts with the sorbent particles thereby forming a sorbent-metal complex under UV irradiation.

Genetic Transformation of Metroxylon sagu (Rottb.) Cultures via Agrobacterium-Mediated and Particle Bombardment

PubMed Central

Ibrahim, Evra Raunie

2014-01-01

Sago palm (Metroxylon sagu) is a perennial plant native to Southeast Asia and exploited mainly for the starch content in its trunk. Genetic improvement of sago palm is extremely slow when compared to other annual starch crops. Urgent attention is needed to improve the sago palm planting material and can be achieved through nonconventional methods. We have previously developed a tissue culture method for sago palm, which is used to provide the planting materials and to develop a genetic transformation procedure. Here, we report the genetic transformation of sago embryonic callus derived from suspension culture using Agrobacterium tumefaciens and gene gun systems. The transformed embryoids cells were selected against Basta (concentration 10 to 30 mg/L). Evidence of foreign genes integration and function of the bar and gus genes were verified via gene specific PCR amplification, gus staining, and dot blot analysis. This study showed that the embryogenic callus was the most suitable material for transformation as compared to the fine callus, embryoid stage, and initiated shoots. The gene gun transformation showed higher transformation efficiency than the ones transformed using Agrobacterium when targets were bombarded once or twice using 280 psi of helium pressure at 6 to 8 cm distance. PMID:25295258

Structure-conserving spontaneous transformations between nanoparticles

NASA Astrophysics Data System (ADS)

Krishnadas, K. R.; Baksi, Ananya; Ghosh, Atanu; Natarajan, Ganapati; Pradeep, Thalappil

2016-11-01

Ambient, structure- and topology-preserving chemical reactions between two archetypal nanoparticles, Ag25(SR)18 and Au25(SR)18, are presented. Despite their geometric robustness and electronic stability, reactions between them in solution produce alloys, AgmAun(SR)18 (m+n=25), keeping their M25(SR)18 composition, structure and topology intact. We demonstrate that a mixture of Ag25(SR)18 and Au25(SR)18 can be transformed to any arbitrary alloy composition, AgmAun(SR)18 (n=1-24), merely by controlling the reactant compositions. We capture one of the earliest events of the process, namely the formation of the dianionic adduct, (Ag25Au25(SR)36)2-, by electrospray ionization mass spectrometry. Molecular docking simulations and density functional theory (DFT) calculations also suggest that metal atom exchanges occur through the formation of an adduct between the two clusters. DFT calculations further confirm that metal atom exchanges are thermodynamically feasible. Such isomorphous transformations between nanoparticles imply that microscopic pieces of matter can be transformed completely to chemically different entities, preserving their structures, at least in the nanometric regime.

Speciation and transformation of heavy metals during vermicomposting of animal manure.

PubMed

Lv, Baoyi; Xing, Meiyan; Yang, Jian

2016-06-01

This work was conducted to evaluate the effects of vermicomposting on the speciation and mobility of heavy metals (Zn, Pb, Cr, and Cu) in cattle dung (CD) and pig manure (PM) using tessier sequential extraction method. Results showed that the pH, total organic carbon and C/N ratio were reduced, while the electric conductivity and humic acid increased after 90days vermicomposting. Moreover, the addition of earthworm could accelerate organic stabilization in vermicomposting. The total heavy metals in final vermicompost from CD and PM were higher than the initial values and the control without worms. Sequential extraction indicated that vermicomposting decreased the migration and availability of heavy metals, and the earthworm could reduce the mobile fraction, while increase the stable fraction of heavy metals. Furthermore, these results indicated that vermicomposting played a positive role in stabilizing heavy metals in the treatment of animal manure. Copyright © 2016 Elsevier Ltd. All rights reserved.

A strain-mediated corrosion model for bioabsorbable metallic stents.

PubMed

Galvin, E; O'Brien, D; Cummins, C; Mac Donald, B J; Lally, C

2017-06-01

This paper presents a strain-mediated phenomenological corrosion model, based on the discrete finite element modelling method which was developed for use with the ANSYS Implicit finite element code. The corrosion model was calibrated from experimental data and used to simulate the corrosion performance of a WE43 magnesium alloy stent. The model was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile. The non-linear plastic strain model, extrapolated from the experimental data, was also found to adequately capture the corrosion-induced reduction in the radial stiffness of the stent over time. The model developed will help direct future design efforts towards the minimisation of plastic strain during device manufacture, deployment and in-service, in order to reduce corrosion rates and prolong the mechanical integrity of magnesium devices. The need for corrosion models that explore the interaction of strain with corrosion damage has been recognised as one of the current challenges in degradable material modelling (Gastaldi et al., 2011). A finite element based plastic strain-mediated phenomenological corrosion model was developed in this work and was calibrated based on the results of the corrosion experiments. It was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile and the corrosion-induced reduction in the radial stiffness of the stent over time. To the author's knowledge, the results presented here represent the first experimental calibration of a plastic strain-mediated corrosion model of a corroding magnesium stent. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Characteristics of Mitochondrial Transformation into Human Cells

PubMed Central

Kesner, E. E.; Saada-Reich, A.; Lorberboum-Galski, H.

2016-01-01

Mitochondria can be incorporated into mammalian cells by simple co-incubation of isolated mitochondria with cells, without the need of transfection reagents or any other type of intervention. This phenomenon was termed mitochondrial transformation, and although it was discovered in 1982, currently little is known regarding its mechanism(s). Here we demonstrate that mitochondria can be transformed into recipient cells very quickly, and co-localize with endogenous mitochondria. The isolated mitochondria interact directly with cells, which engulf the mitochondria with cellular extensions in a way, which may suggest the involvement of macropinocytosis or macropinocytosis-like mechanisms in mitochondrial transformation. Indeed, macropinocytosis inhibitors but not clathrin-mediated endocytosis inhibition-treatments, blocks mitochondria transformation. The integrity of the mitochondrial outer membrane and its proteins is essential for the transformation of the mitochondria into cells; cells can distinguish mitochondria from similar particles and transform only intact mitochondria. Mitochondrial transformation is blocked in the presence of the heparan sulfate molecules pentosan polysulfate and heparin, which indicate crucial involvement of cellular heparan sulfate proteoglycans in the mitochondrial transformation process. PMID:27184109

Abundance, Composition and Activity of Ammonia Oxidizer and Denitrifier Communities in Metal Polluted Rice Paddies from South China

PubMed Central

Liu, Yuan; Liu, Yongzhuo; Ding, Yuanjun; Zheng, Jinwei; Zhou, Tong; Pan, Genxing; Crowley, David; Li, Lianqing; Zheng, Jufeng; Zhang, Xuhui; Yu, Xinyan; Wang, Jiafang

2014-01-01

While microbial nitrogen transformations in soils had been known to be affected by heavy metal pollution, changes in abundance and community structure of the mediating microbial populations had been not yet well characterized in polluted rice soils. Here, by using the prevailing molecular fingerprinting and enzyme activity assays and comparisons to adjacent non-polluted soils, we examined changes in the abundance and activity of ammonia oxidizing and denitrifying communities of rice paddies in two sites with different metal accumulation situation under long-term pollution from metal mining and smelter activities. Potential nitrifying activity was significantly reduced in polluted paddies in both sites while potential denitrifying activity reduced only in the soils with high Cu accumulation up to 1300 mg kg−1. Copy numbers of amoA (AOA and AOB genes) were lower in both polluted paddies, following the trend with the enzyme assays, whereas that of nirK was not significantly affected. Analysis of the DGGE profiles revealed a shift in the community structure of AOA, and to a lesser extent, differences in the community structure of AOB and denitrifier between soils from the two sites with different pollution intensity and metal composition. All of the retrieved AOB sequences belonged to the genus Nitrosospira, among which species Cluster 4 appeared more sensitive to metal pollution. In contrast, nirK genes were widely distributed among different bacterial genera that were represented differentially between the polluted and unpolluted paddies. This could suggest either a possible non-specific target of the primers conventionally used in soil study or complex interactions between soil properties and metal contents on the observed community and activity changes, and thus on the N transformation in the polluted rice soils. PMID:25058658

When nurse emotional intelligence matters: How transformational leadership influences intent to stay.

PubMed

Wang, Lin; Tao, Hong; Bowers, Barbara J; Brown, Roger; Zhang, Yaqing

2018-05-01

The purpose of this study was to examine the role of staff nurse emotional intelligence between transformational leadership and nurse intent to stay. Nurse intent to stay and transformational leadership are widely recognized as vital components of nurse retention. Staff nurse emotional intelligence that has been confirmed improvable has been recently recognized in the nursing literature as correlated with retention. Yet, the nature of the relationships among these three variables is not known. Cross-sectional data for 535 Chinese nurses were analysed using Structural Equation Modelling. Transformational leadership and staff nurse emotional intelligence were significant predictors of nurse intent to stay, accounting for 34.3% of the variance in nurse intent to stay. Staff nurse emotional intelligence partially mediates the relationship between transformational leadership and nurse intent to stay. The findings of the study emphasized the importance of transformational leadership in enhancing nurse emotional intelligence and to provide a deeper understanding of the mediating role of emotional intelligence in the relationship between nurse manager's transformational leadership and nurse's intent to stay. Nurse leaders should develop training programmes to improve nursing manager transformational leadership and staff nurse emotional intelligence in the workplace. © 2018 John Wiley & Sons Ltd.

Effects of Phase Transformations and Dynamic Material Strength on Hydrodynamic Instability Evolution in Metals

NASA Astrophysics Data System (ADS)

Opie, Saul

Hydrodynamic phenomena such as the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities can be described by exponential/linear growth of surface perturbations at a bimaterial interface when subjected to constant/impulsive acceleration. A challenge in designing systems to mitigate or exploit these effects is the lack of accurate material models at large dynamic strain rates and pressures. In particular, little stress-strain constitutive information at large strain rates and pressures is available for transient material phases formed at high pressures, and the continuum effect the phase transformation process has on the instability evolution. In this work, a phase-aware isotropic strength model is developed and partially validated with a novel RM-based instability experiment in addition to existing data from the literature. With the validated material model additional simulations are performed to provide insight into to the role that robust material constitutive behavior (e.g., pressure, temperature, rate dependence) has on RM instability and how RM instability experiments can be used to characterize and validated expected material behavior. For phase aware materials, particularly iron in this work, the simulations predict a strong dependence on the Atwood number that single phase materials do not have. At Atwood numbers close to unity, and pressures in the high pressure stability region, the high pressure phase dominates the RM evolution. However, at Atwood numbers close to negative one, the RM evolution is only weakly affected by the high-pressure phase even for shocks well above the phase transformation threshold. In addition to RM evolution this work looks at the closely related shock front perturbation evolution. Existing analytical models for isentropic processes in gases and liquids are modified for metal equation of states and plastic behavior for the first time. It is found that the presence of a volume collapsing phase transformation with increased

Real time dynamics of Si magic clusters mediating phase transformation: Si(111)-(1 × 1) to (7 × 7) reconstruction revisited

NASA Astrophysics Data System (ADS)

Ong, Wei Jie; Tok, Eng Soon

2012-07-01

Using Scanning Tunneling Microscope (STM), we show that the surface undergoes phase transformation from disordered "1 × 1" to (7 × 7) reconstruction which is mediated by the formation of Si magic clusters. Mono-disperse Si magic clusters of size ~ 13.5 ± 0.5 Å can be formed by heating the Si(111) surface to 1200 °C and quenching it to room temperature at cooling rates of at least 100 °C/min. The structure consists of 3 tetra-clusters of size ~ 4.5 Ǻ similar to the Si magic clusters that were formed from Si adatoms deposited by Si solid source on Si(111)-(7 × 7) [1]. Using real time STM scanning to probe the surface at ~ 400 °C, we show that Si magic clusters pop up from the (1 × 1) surface and form spontaneously during the phase transformation. This is attributed to the difference in atomic density between "disordered 1 × 1" and (7 × 7) surface structures which lead to the release of excess Si atoms onto the surface as magic clusters.

The Agrobacterium-mediated transformation of common wheat (Triticum aestivum L.) and triticale (x Triticosecale Wittmack): role of the binary vector system and selection cassettes.

PubMed

Bińka, Agnieszka; Orczyk, Wacław; Nadolska-Orczyk, Anna

2012-02-01

The influence of two binary vector systems, pGreen and pCAMBIA, on the Agrobacterium-mediated transformation ability of wheat and triticale was studied. Both vectors carried selection cassettes with bar or nptII driven by different promoters. Two cultivars of wheat, Kontesa and Torka, and one cultivar of triticale, Wanad, were tested. The transformation rates for the wheat cultivars ranged from 0.00 to 3.58% and from 0.00 to 6.79% for triticale. The best values for wheat were 3.58% for Kontesa and 3.14% for Torka, and these were obtained after transformation with the pGreen vector carrying the nptII selection gene under the control of 35S promoter. In the case of the bar selection system, the best transformation rates were, respectively, 1.46 and 1.79%. Such rates were obtained when the 35S::bar cassette was carried by the pCAMBIA vector; they were significantly lower with the pGreen vector. The triticale cultivar Wanad had its highest transformation rate after transformation with nptII driven by 35S in pCAMBIA. The bar selection system for the same triticale cultivar was better when the gene was driven by nos and the selection cassette was carried by pGreen. The integration of the transgenes was confirmed with at least three pairs of specific starters amplifying the fragments of nptII, bar, or gus. The expression of selection genes, measured by reverse transcriptase polymerase chain reaction (RT-PCR) in relation to the actin gene, was low, ranging from 0.00 to 0.63 for nptII and from 0.00 to 0.33 for bar. The highest relative transcript accumulation was observed for nptII driven by 35S and expressed in Kontesa that had been transformed with pGreen.

Environmental epigenetics in metal exposure

PubMed Central

Martinez-Zamudio, Ricardo

2011-01-01

Although it is widely accepted that chronic exposure to arsenite, nickel, chromium and cadmium increases cancer incidence in individuals, the molecular mechanisms underlying their ability to transform cells remain largely unknown. Carcinogenic metals are typically weak mutagens, suggesting that genetic-based mechanisms may not be primarily responsible for metal-induced carcinogenesis. Growing evidence shows that environmental metal exposure involves changes in epigenetic marks, which may lead to a possible link between heritable changes in gene expression and disease susceptibility and development. Here, we review recent advances in the understanding of metal exposure affecting epigenetic marks and discuss establishment of heritable gene expression in metal-induced carcinogenesis. PMID:21610324

Degradation of anthracene by laccase of Trametes versicolor in the presence of different mediator compounds.

PubMed

Johannes, C; Majcherczyk, A; Hüttermann, A

1996-10-01

Laccase of Trametes versicolor was generally able to oxidize anthracene in vitro. After 72 h incubation about 35% of the anthracene was transformed stoichiometrically to 9,10-anthraquinone. Transformation of anthracene increased rapidly in the presence of different mediators that readily generate stable radicals: 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1-hydroxybenzotriazole. For the reaction, the presence of both the laccase and the mediator was necessary. In the presence of 0.005 mM 1-hydroxybenzotriazole this conversion had removed 47% of the anthracene after 72 h; 75% of the substrate was oxidized during this period when ABTS (1 mM) was used as mediator. In contrast to reactions without or with only low concentrations of a mediator, there was a discrepancy between the disappearance of anthracene and the formation of 9,10-anthraquinone in mediator-forced reactions. Coupling-products of mediators with anthracene degradation products were found. Anthracene disappeared nearly completely after incubation for 72 h with laccase in a 0.1 mM solution of 1-hydroxybenzotriazole and was transformed to 9,10-anthraquinone in about 80% yield; 90% of the substrate was transformed in the presence of ABTS (2.0 mM) resulting again in 80% quinone. Phenothiazine was not effective in this system.

Interphase Transformations at Metal (Copper, Iron)-Polymer Gel-Electrolyte Interfaces

NASA Astrophysics Data System (ADS)

Lyamina, G. V.; Dubinina, O. V.; Vaitulevich, E. A.; Mokrousov, G. M.

2018-07-01

The results from studies of the interface boundaries between metals (copper and iron) and gel electrolyte based on methacrylic copolymers are organized systematically. In contrast to processes in liquid electrolytes, a number of key features of the reactions that occur at such interfaces are revealed: a diffusion limiting stage; a lack of reverse reactions; and the formation of coordination compounds of metal ions with the functional groups of polymers, the stabilities of which are several orders of magnitude greater than that of coordination with their low-molecular weight counterparts. It is shown that processes which employ polymeric organogels can be used for the careful cleaning of the metal surfaces, and for the formation of a desired phase composition on the latter.

Soybean (Glycine max) transformation using mature cotyledonary node explants.

PubMed

Olhoft, Paula M; Donovan, Christopher M; Somers, David A

2006-01-01

Agrobacterium tumefaciens-mediated transformation of soybeans has been steadily improved since its development in 1988. Soybean transformation is now possible in a range of genotypes from different maturity groups using different explants as sources of regenerable cells, various selectable marker genes and selective agents, and different A. tumefaciens strains. The cotyledonary-node method has been extensively investigated and across a number of laboratories yields on average greater than 1% transformation efficiency (one Southern-positive, independent event per 100 cotyledonary-node explants). Continued improvements in the cotyledonary-node method concomitant with further increases in transformation efficiency will enhance broader adoption of this already productive transformation method for use in crop improvement and functional genomics research efforts.

Mediating the Conflict between Transformative Pedagogy and Bureaucratic Practice