bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic Feasibility of Corn Stover Torrefaction for Distributed Processing Systems
Authors: Almberg Evan R. , Twedt Michael P. , Gerometta Christina , Gent Stephen P.
Published: November 2016

This study investigated the economic feasibility of distributed or decentralized torrefaction bio-refining using corn stover feedstock to generate value added products. Distributed bio-refining systems would be able to operate on private farm and commercial scales, eliminating the need for large capital investment for large processing facilities and decreasing logistical concerns for harvesting and marketing corn stover. A techno-economic model was developed to analyze the economics of harvesting techniques, logistics, processing requirements, and end product utilization. With the model, a base case analysis was established to analyze average values and to create a basis in which to compare a variety of economic scenarios. A sensitivity analysis was also completed to investigate outcomes based on variability of crop yields and product price, as well as costs associated with harvesting stover, input for operating the torrefaction system, and capital costs of equipment. Results of the analyses were quantified with respect to input costs required to generate torrefied products, potential profit of processed products, and the payback period of the production and conversion system. Preliminary results indicated that processing corn stover feedstock within a distribution torrefaction bio-refining system had high potential, in terms of economic feasibility, over a wide range of scenarios. Results indicated that payback periods as low as five years were possible under a wide variety of applications and operating costs. In addition to operating economically, it was also shown that end products could have increasing profit potential as a value added product.
Effect of Thermal Depolymerization of Wasted Food Extracts on Alternate Fuel Production
Authors: Herndon Marcus
Published: November 2016

Human activities like fossil fuel retrieval, biomass burning, waste disposal, and residential and commercial use of energy are continuing to effect the Earth’s energy budget by changing the emissions and resulting atmospheric concentrations of radioactively important gases, aerosols, and by changing land surface properties. These activities negatively contribute to Earth’s greenhouse gases including water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Approximately 82% of greenhouse gases are developed from the United States, Asia, and Europe alone. Food and their extraction processes, including transportation of those extracts, account for about 35% of those greenhouse gases. This includes wasted, rotten, and uneaten food. About 40% of food in the United States today goes uneaten, resulting in more than 20 pounds of food per person every month. Not only does this mean that Americans are throwing out upwards of $165 billion each year, amounting to $1,350 to more than $2,275 annually in waste per family of four, but also 25 percent of all freshwater and huge amounts of unnecessary chemicals, energy, and land. Moreover, almost all of that uneaten food ends up rotting in landfills. This number has increased, in regards to organic matter, from approximately 16 percent of U.S. methane emissions in 2010 upwards to 25 percent in 2012. With the increase in supply and demand of food, in addition to the lower consumer cost, the statistics of wasted feedstocks are rapidly increasing. The purpose of this research is to utilize wasted food to extract natural hydrocarbon oils through thermal depolymerization in order to develop an alternative fuel. Thermal depolymerization is a hydrous pyrolysis process that breaks down long chained polymers into simpler compounds and light hydrocarbons, much of which can be separated and used for fuel. Polymers include essentially all organic matter i.e. matter made of living or once-living things, which include petroleum products like plastic, styro-foam, and nylon, as well as plant and animal material, and manure. Potatoes and corn starch were used as feedstocks for this research and thermal depolymerization was conducted on the feedstocks for analysis and fuel collection. With optimum use and a mature thermal depolymerization technology, the Earth might comfortably support 10 times its current population at a high standard of living. There is enough biomass existing now accessible on the surface of the earth to provide 100 years of human energy use.
Small-Scale Thermal Energy Storage With Capillary Conductivity Enhancement
Authors: Hays A. , Borquist E. , Bailey D. , Wood D. , Weiss L.
Published: November 2016

Thermal energy is a leading topic of discussion in energy conservation and environmental fields. Specifically for large-scale applications solar energy and concentrated solar power (CSP) systems use techniques that include thermal energy storage systems and phase change materials to harvest energy. However, on the smaller centimeter scale, there have been historically fewer investigations of these same techniques. The main goal of this paper is to investigate thermal energy storage (TES) as applied to a small scale system for thermal energy capture. Typical large-scale TES consists of a phase change material that usually employs a wax or oil medium held within a conductive container. The system stores the energy when the wax medium undergoes a phase change. In typical applications like buildings, the system absorbs and stores incoming thermal energy during the day, and releases it back to the surrounding environment as temperatures cool at night.

This paper presents a new TES unit designed to integrate with a thermoelectric for energy harvesting application in small, cm-scale applications. In this manner, the TES serves as a thermal battery and source for the thermoelectric, even when originating power supply is interrupted. A unique feature of this TES is the inclusion of internal heat pipes. These heat pipes are fabricated from copper tubing and filled with working fluid, mounted vertically, and immersed in the wax medium of the TES. This transfers heat to the wax by means of thermal conductivity enhancement as an element of the heat pipe operation. This represents a first of its kind in this small-scale, thermal harvesting application.

As tested, the TES rests atop a low temperature (60 °C) heat source with a heat sink as the final setup component. The heat sink serves to simulate thermal energy rejection to a future thermoelectric device. To measure the temperature change of the device, thermocouples are placed on either side of the TES, and a third placed on the heat source to ensure that the energy input is appropriate and constant. Heat flux sensors (HFS) are placed between the heat source and the TES and between the TES and heat sink to monitor heat transferred to and from the device.

The TES is tested in a variety constructions as part of this effort. Basic design of the storage volume as well as fluid fill levels within the heat pipes are considered. Varying thermal energy inputs are also studied. Temperature and heat flux data are compared to show the thermal absorption capability and operating average thermal conductivities of the TES units. The baseline average thermal conductivity of the TES is approximately 0.5 W/mK. This represents the TES with wax alone filling the internal volume. Results indicate a fully functional, heat pipe TES capable of 8.23 W/mK.
Efficient Wind Turbine Micrositing in Large-Scale Wind Farms
Authors: Guirguis David , Romero David A. , Amon Cristina H.
Published: November 2016

As wind energy is established as a sustainable alternative source of electricity, very large-scale wind farms with hundreds of turbines are becoming increasingly common. For the optimal design of wind farm layouts, the number of decision variables is at least twice the number of turbines (e.g., the Cartesian coordinates of each turbine). As the number of turbines increases, the computational cost incurred by the optimization solver to converge to a satisfactory solution increases as well. This issue represents a serious limitation in the computer-aided design of large wind farms. Moreover, the wind farm domains are typically highly constrained including land-availability and proximity constraints. These non-linear constraints increase the complexity of the optimization problem and decrease the likelihood of obtaining even a feasible solution. Several approaches have been proposed for micrositing of wind turbines, including random searches, mixed-integer programs, and metaheuristics. Each of these methods has its own trade-off between the quality of optimized layouts and the computational cost of obtaining the solution. In this paper, we demonstrate the capability of non-linear mathematical programming for optimizing very large-scale wind farms by leveraging explicit, analytical derivatives for the objective and constraint functions, thus overcoming the aforementioned limitations while also providing convergence and local optimality guarantees. For that purpose, two large farms with hundreds of turbines and significant land-use constraints are solved on a standard personal computer.
Meta-Modeling Based Optimization of a Directional Augmentation Technique on Improving the Performance of Six Blades Savonius Rotor Using CFD Analysis
Authors: Ferdoues Mst Sunzida , Vijayaraghavan Krishna
Published: November 2016

The performance of Savonius wind turbine can be improved by increasing the effective wind velocity. One of the methods of improving the effective wind velocity is using directional augmentation technique, which actually affects the Omnidirectional capability of the Savonius rotor. This paper works on this method by using convergent nozzle at the outlet of the rotor. The whole work is based on Metamodeling based optimization and numerical simulation. Reynolds averaged Navier-stokes equation (RANS) based turbulence model has been used for simulations, such as static simulation and dynamic simulation. The CFD simulations are validated against previously published experimental data. The optimization procedure is performed by integrating the Design of Experiment (DOE), Computational Fluid Dynamics (CFD), Response Surface Model (RSM) and analysis of variance (ANOVA). The meta-model is able to identify significant design variable and the interactions. The proposed optimal nozzle is shown to improve the coefficient of the moment from 0.3 to 0.44.
Performance Enhancement of Concentrated Photovoltaic System Using Phase-Change Material
Authors: Emam Mohamed , Ahmed Mahmoud , Ookawara Shinichi
Published: November 2016

The contribution of renewable energy to the worldwide sustainable development and environmental preservation has been widely recognized nowadays. Concentrated photovoltaic (CPV) system, in particular, has received an extensive research effort as one of the most promising applications of solar energy. Due to the high concentration r1atio, a significant increase in the CPV temperature occurs. Consequently, the conversion efficiency deteriorates; thereby thermal regulation of a CPV system is of great importance. Therefore, a hybrid system including CPV, and phase change material (PCM) is considered as a single module to achieve higher solar conversion efficiency. Such a system provides a high-energy storage density at a constant temperature which corresponds to the phase transition temperature of the material. In the present study, a comprehensive model for CPV layers integrated with PCM was developed. This model was a coupled of a thermal model for CPV layers and fluid dynamic heat transfer model that took into account the phase-change phenomenon using enthalpy method, and the conversion of solar incident radiations. The effects of specific two variables on the solar cell temperature were investigated which were the PCM thickness of 50, 100, and 200 mm and concentration ratio (CR) from 5 to 20. It was found that the use of PCM could achieve a significant reduction of solar cell temperature. The solar cell temperature reduced from 180 °C to 38 °C by using PCM of thickness 200 mm at CR=5, while at the same PCM thickness, the cell temperature reduced from 510°C to 64°C at CR=20. Furthermore, the solar cell temperature was maintained at an average temperature of 38 °C for 8.4 hours using a 200 mm thickness of PCM at CR=5. In addition, at CR=20, the solar cell temperature was maintained at an average temperature of 64 °C for 2.0 hours using a 200 mm thickness of PCM. From the results, it was indicated that the use of PCM was an effective cooling technique since it attained a significant reduction in solar cell temperature, especially at high concentration ratio.
Transient Behavior of an Ammonia-Based Energy Recovery System
Authors: Bran-Anleu Gabriela , Kavehpour H. Pirouz , Lavine Adrienne S.
Published: November 2016

An ammonia thermochemical energy storage system consists of an endothermic reaction that disassociates ammonia into hydrogen using the solar energy, which can be stored for future use. The reverse reaction is carried out in the energy recovery process; the ammonia synthesis reaction is used to heat supercritical steam to temperatures on the order of 650 degrees Celsius as required for a supercritical steam Rankine cycle. The goal of this paper is to investigate the transient response in a synthesis reactor-heat-exchanger. It is desired to predict the time the system takes to reach steady state and the effect a perturbation has on the temperature response of the system. A numerical model has been developed to investigate the transient behavior of an ammonia synthesis reactor-heat exchanger. The model consists of a transient one dimensional concentric tube counter-flow reactor-heat exchanger. The effect of gas mass flow rate and initial gas temperature was investigated. Results show that as gas mass flow rate increases, the time for the outlet steam temperature to reach steady state decreases. For low gas mass flow rates, the required outlet steam temperature is not achieved.
Energy Efficiency Policy Roadmap for the State of Kuwait
Authors: Al-Ragom Fotouh A. , Alsayegh Osamah A. , Sreekanth K. J. , Alghimlas Fareed
Published: November 2016

This paper proposes a national energy efficiency policy to go along with the Development Plan of the State of Kuwait 2015–2020. Obstacles hindering the energy savings including, the general consensus of government officials, securing national energy funds, engaging various stakeholders, setting targets and establishing benchmarks and legal framework to monitor and gage progress are discussed. A SWOT analysis is conducted to arrive at short term (5 years) and long term (15 years) milestones for the policy roadmap needed to achieve optimum potential saving. Compared with the present consumption pattern (business as usual), primary energy saving will reach 2.4% by 2020 and extending to 30% saving by 2035. This saving target is the result of analyzing various policy scenarios through the application of energy conservation code, building energy audits, appliance labeling, building labeling, smart building energy monitoring and control, vehicle energy labeling, and electric vehicles.
Induction-heated nanoimprint on soda-lime glass using sapphire molds
Authors: Cai Jingxuan , Li Shijie , Guo Xu , Ge Haixong , Li Wen-Di
Published: November 2016

The authors developed an induction-heated high-temperature thermal nanoimprint process to directly transfer nanoscale features on sapphire molds to soda-lime glass substrates. Nanoholes of a 650-nm-period hexagonal lattice were directly imprinted in soda-lime glass using the induction-heated thermal nanoimprint configuration as an experimental demonstration. The morphology of nanostructures imprinted on glass substrates at different imprinting process parameters was characterized by scanning electron microscopy and atomic force microscopy and further numerically investigated using a finite element method. The soda-lime glass substrates imprinted with nanohole arrays were then used as secondary templates for further transferring nanostructures onto cyclic olefin copolymer films through another thermal nanoimprint process. The authors also demonstrated surface-enhanced Raman spectroscopy sensing applications on these nanostructured glass substrates after coating them with a thin layer of gold.
The Role of Psychological Flexibility in Injury Rehabilitation
Authors: DeGaetano Jessica J. , Wolanin Andrew T. , Marks Donald R. , Eastin Shiloh M.
Published: November 2016

The purpose of this study was to explore the influence of psychosocial factors and psychological flexibility on rehabilitation protocol adherence in a sample of injured collegiate athletes. Self-report measures were given to injured athletes before the start of a physical rehabilitation protocol. Upon completion of rehabilitation, each athlete was assessed by the chief athletic trainer using a measure of rehabilitation adherence. Correlational analyses and bootstrapped logistic regression analyses were conducted to determine whether broad psychosocial factors and level of psychological flexibility predicted engagement and adherence to a rehabilitation protocol. Psychological flexibility, as measured on the Acceptance and Action Questionnaire (2nd ed.; Bond et al., 2011), contributed significantly to the overall logistic regression model. Study findings suggested that assessment of psychological flexibility could give medical providers a way to evaluate both quickly and quantitatively potentially problematic behavioral responding among injured athletes, allowing for more effective adherence monitoring.
Caspase-2: Divide and conquer
Authors: Martin Ian
Published: November 2016

Preventing caspase-2 cleavage of tau blocks memory impairment in an animal model of Alzheimer’s disease.
GAL3 gene product is required for maintenance of the induced state of the GAL cluster genes in Saccharomyces cerevisiae
Authors: Nogi Y
Published: November 2016

The activities of the first three enzymes for galactose catabolism normally become detectable within 15 min after the addition of galactose into a culture of the yeast Saccharomyces cerevisiae. In S. cerevisiae with a recessive mutation termed gal3, a longer-than-normal lag is observed before the appearance of the enzyme activities (O. Winge and C. Roberts, C. R. Trav. Lab. Carlsberg Ser. Physiol. 24:263-315, 1948). I isolated two S. cerevisiae mutants with temperature-sensitive defects in the GAL3 gene. Temperature shift experiments with one of those mutants led to the conclusion that the GAL3 function is required not only for the initiation of enzyme induction but also for the maintenance of the induced state in galactose-nonfermenting S. cerevisiae because of a defect in any of the genes for the galactose-catabolizing enzymes, such as gal1 or gal10. In contrast, the GAL3 function is phenotypically dispensable in galactose-metabolizing S. cerevisiae. Thus, the normal catabolism of galactose can substitute for the GAL3 function.
Identification and properties of chlamydial polypeptides that bind eucaryotic cell surface components
Authors: Hackstadt T
Published: November 2016

An electroblotting technique was used to identify proteins of Chlamydia that bound surface-radioiodinated and Triton X-100-solubilized HeLa cell extracts. Two proteins, with apparent molecular masses of 18 and 32 kilodaltons (kDa), that bound HeLa cell surface components were identified on Chlamydia trachomatis L2 elementary bodies (EBs). Radioiodinated heparin, which disrupts chlamydial association with cultured cells, was also bound by these proteins. These two proteins were found on EBs but were absent or were present in reduced amounts on the noninfectious reticulate bodies. All C. trachomatis strains tested displayed two such proteins, although the apparent molecular weight of the larger protein varied with serotype in correlation with biotype and the disease that it caused. Two Chlamydia psittaci strains examined displayed only a single binding protein in the range of 17 to 19 kDa. All of the binding proteins stained intensely and distinctively on silver-stained sodium dodecyl sulfate-polyacrylamide gels and displayed an unusual sensitivity to reducing agents. The 32-kDa protein was not seen and did not bind 125I-labeled HeLa cell components if the EBs were solubilized in the presence of 2-mercaptoethanol. The 32-kDa protein was not affected by dithiothreitol, however. Similar to the effect of 2-mercaptoethanol, the 32-kDa protein was not visualized after treatment of EBs with the protease inhibitors tosyl-phenylalanine chloromethyl ketone (TPCK) or tosyl-lysine chloromethyl ketone (TLCK). TPCK and TLCK also abolished infectivity as did the alkylating agents N-ethylmaleimide and iodoacetamide, yet the latter two agents did not affect the appearance of the 32-kDa protein. These proteins were not detected in immunoblots with either rabbit antisera to C. trachomatis L2 EBs or by serum from a patient with lymphogranuloma venereum. The role of these proteins in the interaction of chlamydiae with host cells is not clear, but the binding of eucaryotic cell surface components and heparin, presence only during the infectious stage of the life cycle, variation between serotypes in correlation with disease, and sensitivity to reducing agents or protease inhibitors, collectively, suggest a role for these proteins in parasite-host interactions.
Regulation of glutamine synthesis by glycine and serine in Neurospora crassa
Authors: Hernández G , Mora Y , Mora J
Published: November 2016

The biosynthetic activities of the polypeptide subunits alpha and beta of glutamine synthetase (GS) were inhibited in vitro by glycine and serine. These amino acids inhibited the growth of a mutant strain with partial GS activity when grown on glutamate as the nitrogen source and also blocked the synthesis of the glutamine in vivo, thus demonstrating the inhibitory effect on GS activity in vivo. Glycine and serine lowered the intracellular glutamine pool and regulated GS beta synthesis. A preferential induction of synthesis of the GS beta polypeptide was observed when either of these amino acids was present in the medium. On this basis, we obtained a glycine-sensitive mutant which showed a structural alteration of the GS beta polypeptide. The double regulatory effect of either glycine or serine on glutamine synthesis may be considered an example of the regulation of glutamine synthesis by alpha-amino nitrogen. It may be a mechanism that regulates the assimilation of ammonium into glutamate versus glutamine.
Evolution of the regulatory isozymes of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase present in the Escherichia coli genealogy
Authors: Ahmad S , Rightmire B , Jensen R A
Published: November 2016

The evolutionary history of isozymes for 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase has been constructed in a phylogenetic cluster of procaryotes (superfamily B) that includes Escherichia coli. Members of superfamily B that have been positioned on a phylogenetic tree by oligonucleotide cataloging possess one or more of four distinct isozymes of DAHP synthase. DAHP synthase-0 is insensitive to feedback inhibition, while DAHP synthase-Tyr, DAHP synthase-Trp, and DAHP synthase-Phe are sensitive to feedback inhibition by L-tyrosine, L-tryptophan, and L-phenylalanine, respectively. The evolutionary history of this isozyme family can be deduced within superfamily B by using a cladistic methodology of maximum parsimony (R. A. Jensen, Mol. Biol. Evol. 2:92-108, 1985). DAHP synthase-0 was found in Acinetobacter species and in Oceanospirillum minutulum, organisms that also possess DAHP synthase-Tyr. These two isozymes were apparently present in a common ancestor that predated the evolutionary divergence of contemporary superfamily B sublineages. DAHP synthase-0 is postulated to have been the evolutionary forerunner of DAHP synthase-Trp. The newly evolved DAHP synthase-Trp is postulated to have possessed sensitivity to feedback inhibition by chorismate as well as by L-tryptophan, chorismate sensitivity having been retained in rRNA group I pseudomonads (minor sensitivity), group V pseudomonads (very sensitive), and Lysobacter enzymogenes (ultrasensitive). Organisms constituting the enteric lineage of the phylogenetic tree (including a cluster of four Oceanospirillum species) have all lost the chorismate sensitivity of DAHP synthase-Trp. The absence of DAHP synthase-Phe in the Oceanospirillum cluster of organisms supports the previous conclusion that DAHP synthase-Phe evolved recently within superfamily B, being present only Escherichia coli and its close relatives.
Isolation and characterization of lon mutants in Salmonella typhimurium
Authors: Downs D , Waxman L , Goldberg A L , Roth J
Published: November 2016

In this paper we report the isolation and characterization of lon mutants in Salmonella typhimurium. The mutants were isolated by using positive selection by chlorpromazine resistance. The physiological and biochemical properties of the lon mutants in S. typhimurium are very similar to those of Escherichia coli lon mutants. Mutants altered at this locus contain little or no activity of the ATP-dependent protease La and show a number of pleiotropic phenotypes, including increased production of capsular polysaccharides, increased sensitivity to UV light and other DNA-damaging agents, and a decreased ability to degrade abnormal proteins.
Posttranscriptional autoregulation of Escherichia coli threonyl tRNA synthetase expression in vivo
Authors: Butler J S , Springer M , Dondon J , Grunberg-Manago M
Published: November 2016

Five mutations in thrS, the gene for threonyl-tRNA synthetase, have been characterized, and the sites of the mutations have been localized to different regions of the thrS gene by recombination with M13 phage carrying portions of the thrS gene. Quantitative immunoblotting shows that some of these mutations cause the overproduction of structurally altered threonyl-tRNA synthetase in vivo. The amounts of in vivo thrS mRNA as measured by quantitative hybridization are, however, the same as wild-type levels for each mutant. These results demonstrate that the expression of threonyl-tRNA synthetase is autoregulated at the posttranscriptional level in vivo.
Genetic and molecular analysis of aroL, the gene for shikimate kinase II in Escherichia coli K-12
Authors: DeFeyter R C , Pittard J
Published: November 2016

The gene aroL in Escherichia coli K-12, specifying shikimate kinase II, was contransduced with proC at a frequency of 99%. The gene order is lac proC aroL. A 2.7-kilobase BamHI fragment containing aroL+ was cloned into pBR322. This plasmid conferred highly elevated levels of shikimate kinase synthesis which were subject to repression control by tyrR. The aroL gene was localized within a 730-base-pair region by both subcloning and insertional mutagenesis with Tn1000. A second gene, designated aroM and encoding a protein of molecular weight 26,000, is cotranscribed with aroL. Transcription proceeds in the order aroL aroM in a clockwise direction on the chromosome. The function of aroM remains unknown.
Nucleotide sequence of the transcription unit containing the aroL and aroM genes from Escherichia coli K-12
Authors: DeFeyter R C , Davidson B E , Pittard J
Published: November 2016

The nucleotide sequence of 2,021 base pairs (bp) of DNA containing the Escherichia coli aroLM operon was determined, and the coding regions of both aroL and aroM were identified. The 501-bp intercistronic region between aroL and aroM contains an open reading frame which might encode a 63-residue protein. Northern blots with RNA from strains carrying multicopy aroL+ plasmids detected one longer (2,000-base) and two shorter (950- and 1,100-base) transcripts which contained aroL. It was concluded that the longest transcript, which was not abundant, spanned the entire operon and that the shorter transcripts resulted from either termination or posttranscriptional processing in the intercistronic region. The DNA upstream of aroL contains a number of imperfect palindromes which are closely homologous to known sites of regulation by the TyrR protein in other operons.
Two different parasporal inclusions are produced by Bacillus thuringiensis subsp. finitimus
Authors: Debro L , Fitz-James P C , Aronson A
Published: November 2016

Bacillus thuringiensis subsp. finitimus produced at least two parasporal inclusions. One inclusion was formed within the exosporium and remained with the spore after mother cell lysis. A second inclusion formed somewhat later exterior to the exosporium. Each inclusion contained a major polypeptide of about 135,000 daltons with unique antigenic determinants. This subspecies contained only two plasmids, of 98 and 77 megadaltons (MDa). Strains cured of these plasmids produced only the free inclusion. Since the plasmid-cured strains did not contain DNA sequences homologous to plasmid DNA, the gene for the free-inclusion protein must be encoded in the chromosome. In contrast, the enclosed parasporal inclusion was produced only when the plasmid of 98 MDa was present. In addition, transfer of the 98-MDa plasmid to Bacillus cereus resulted in transcipients that produced small inclusions enclosed within the exosporium, and the protein extracted from these inclusions reacted with antibody specific for enclosed inclusion protein of B. thuringiensis subsp. finitimus. Genes in both the chromosome and a plasmid function in the synthesis of distinct parasporal proteins in this subspecies.
Enzymes of the beta-ketoadipate pathway are inducible in Rhizobium and Agrobacterium spp. and constitutive in Bradyrhizobium spp
Authors: Parke D , Ornston L N
Published: November 2016

Protocatechuate is a universal growth substrate for members of the family Rhizobiaceae, and these bacteria utilize the aromatic compound via the beta-ketoadipate pathway. This report describes transcriptional controls exercised by different subgroups of the Rhizobiaceae over five enzymes that catalyze consecutive reactions in the pathway: protocatechuate oxygenase (EC 1.13.11.3), beta-carboxy-cis,cis-muconate lactonizing enzyme (EC 5.5.1.2), gamma-carboxymuconolactone decarboxylase (EC 4.1.1.44), beta-ketoadipate enol-lactone hydrolase (EC 3.1.1.24), and beta-ketoadipate succinyl-coenzyme A transferase (EC 2.8.3.6). All five enzymes were inducible in the fast-growing strains Agrobacterium rhizogenes, Agrobacterium tumefaciens, Rhizobium fredii, Rhizobium meliloti, Rhizobium leguminosarum, and Rhizobium trifolii. Specific activities in induced cells ranged from 5- to 100-fold greater than those found in uninduced cells. In contrast to the fast-growing strains and members of every other microbial taxon examined to date, the slow-growing Bradyrhizobium japonicum and cowpea Bradyrhizobium spp. constitutively expressed four of the five enzymes; protocatechuate oxygenase was the only inducible enzyme in this group. The slow-growing strains included different DNA homology groups, so it appears likely that constitutive expression of the four enzymes is a common trait in the bradyrhizobia. This property points to the importance of aromatic compounds and aromatic catabolites in the nutrition of these organisms.
Asparaginase II of Saccharomyces cerevisiae: selection of four mutations that cause derepressed enzyme synthesis
Authors: Kamerud J Q , Roon R J
Published: November 2016

A positive selection method was used to isolate four Saccharomyces cerevisiae mutations that cause derepressed synthesis of asparaginase II. The four mutations (and1, and2, and3, and4) were neither closely linked to each other nor linked to previously characterized mutations (asp3, asp6) which cause the complete loss of asparaginase II activity. One of the new mutations (and4) was shown to be allelic to gdh-CR, a pleiotropic mutation which causes derepressed synthesis of a number of enzymes of nitrogen catabolism.
Rhizobium sp. strain ORS571 grows synergistically on N2 and nicotinate as N sources
Authors: Ludwig R A
Published: November 2016

Rhizobium sp. strain ORS571 conducts synergistic, free-living N2 fixation and nicotinate oxidation. Explicitly, ORS571 is able to fix N2 aerobically because 6-OH-nicotinate acts as an intracellular O2 sink. Because 6-OH-nicotinate oxidation is mandatory for aerobic, free-living N2 fixation and because the synergistic processes yield ammonium from substrates (as the nitrogen source for growth), ORS571 is not a diazotroph.
RNase H is not involved in the induction of stable DNA replication in Escherichia coli
Authors: Bialy H , Kogoma T
Published: November 2016

rnh mutations of Escherichia coli inactivating RNase H activity allow the initiation of rounds of DNA replication in the absence of protein synthesis (stable DNA replication). However, levels of RNase H did not change during or after the induction of stable DNA replication in rnh+ strains by incubation with nalidixic acid or UV irradiation.
Discrimination between 34S and 32S during bacterial metabolism of inorganic sulfur compounds
Authors: Fry B , Cox J , Gest H , Hayes J M
Published: November 2016

Sulfur isotope effects during the oxidation of thiosulfate by Thiobacillus versutus were found to be negligible. This result is considered in relation to other oxidative and reductive processes to assess which reactions are most likely to control the isotopic compositions of sulfur compounds in microbial sulfureta.
Purification and properties of shikimate kinase II from Escherichia coli K-12
Authors: DeFeyter R C , Pittard J
Published: November 2016

Shikimate kinase II was purified to near homogeneity from an Escherichia coli strain which overproduced the enzyme. The apparent Km of this isoenzyme for shikimate was 200 microM, and for ATP it was 160 microM. The Km for shikimate is approximately 100-fold lower than the Km of shikimate kinase I, suggesting that shikimate kinase II is the isoenzyme normally functioning in aromatic biosynthesis. Shikimate kinase II is dependent on metal ions for activity.
Genetic and physical characterization of IncM plasmid pBWH1 and its variance among natural isolates
Authors: Hopkins J D , Mayer K H , Gilleece E S , O'Brien T F , Syvanen M
Published: November 2016

We present a genetic and physical characterization of the IncM plasmid pBWH1. A physical map was constructed for the enzymes EcoRI, BamHI, SalI, BglII, HindIII, MstII, and XhoI. A series of deletions and a series of subclones of pBWH1 were constructed and used to determine the locations on this map of the transfer region; the replication region; and the genes determining resistance to beta-lactams, chloramphenicol, the sulfonamides, and gentamicin. We compared 51 different isolates, including isolates which had lost individual antibiotic resistances or the transfer phenotype, and showed that variations occurred in all regions of the plasmid genome. Frequently, correlations could be made between phenotypic variation and variation of the EcoRI fragments which contained the gene determining that phenotype.
Isolation and characterization of ack and pta mutations in Azotobacter vinelandii affecting acetate-glucose diauxie
Authors: McKenney D , Melton T
Published: November 2016

Azotobacter vinelandii mutants defective for acetate utilization that were resistant to fluoroacetate (FA) were isolated. FA-resistant mutant AM6 failed to transport [14C]acetate and lacked enzymatic activity for both acetate kinase and phosphotransacetylase. Growth of wild-type A. vinelandii was sensitive to 10 mM glycine; however, all FA-resistant strains were resistant to glycine toxicity. Isolated mutants that were spontaneously resistant to glycine were also resistant to FA and lacked both acetate kinase and phosphotransacetylase activity. The glycine-resistant mutant AM3, unlike mutant AM6, was capable of growth on acetate. The mutant strain AM6 was unable to growth under acetate-glucose diauxie conditions. Glucose utilization in this mutant, unlike that in wild-type A. vinelandii, was permanently arrested in the presence of acetate. Revertants of strain AM6 were selected on plates with acetate or acetate-glucose. Two classes of revertants were isolated. Class I revertant mutants AM31 and AM35 were positive for both acetate kinase and phosphotransacetylase activities. These revertants were also sensitive to both FA and glycine. Class II revertant strains AM32 and AM34 still lacked acetate kinase and phophotransacetylase activity. Both of these revertants remained resistant to FA and glycine.
Isolation and morphological characterization of a mycelial mutant of Candida albicans
Authors: Hubbard M J , Markie D , Poulter R T
Published: November 2016

In this paper we describe the isolation of a novel strain of Candida albicans which is a mycelium at ambient temperatures. Mutagenesis of C. albicans ATCC 10261 with N-methyl-N-nitro-N-nitrosoguanidine followed by plating on solid media at 28 degrees C yielded colony morphology variants which were characterized by a raised, rough-surfaced colony of irregular outline in marked contrast to the flat, shiny circular colonies of the parental 10261 strain. One mutant colony, hOG301, was studied in detail. Strain hOG301 was stable and exhibited mycelial morphology over a wide temperature range (5 to 40 degrees C) in several media. The hyphae comprising hOG301 mycelium were examined by light microscopy, scanning electron microscopy, and transmission electron microscopy and showed morphological features described in the literature as being typical of both true hyphae and pseudohyphae. In contrast to 10261, hOG301 was not pathogenic after intraperitoneal injection in mice. This is the first report of a mycelial C. albicans that is stable at ambient temperatures.
SOS-independent coupling between DNA replication and cell division in Escherichia coli
Authors: Jaffé A , D'Ari R , Norris V
Published: November 2016

Inhibition of DNA synthesis in Escherichia coli mutants in which the SOS-dependent division inhibitors SfiA and SfiC were unable to operate led to a partial arrest of cell division. This SOS-independent mechanism coupling DNA replication and cell division was characterized with respect to residual division, particle number, and DNA content. Whether DNA replication was blocked in the initiation or the elongation step, numerous normal-sized anucleate cells were produced (not minicells or filaments). Their production was used to evaluate the efficiency of this coupling mechanism, which seems to involve the cell division protein FtsZ (SulB), also known to be the target of the division inhibitors SfiA and SfiC. In the absence of DNA synthesis, the efficiency of coupling was modulated by the cyclic-AMP-cyclic-AMP receptor protein complex, which was required for anucleate cell production.
A single glutamyl-tRNA synthetase aminoacylates tRNAGlu and tRNAGln in Bacillus subtilis and efficiently misacylates Escherichia coli tRNAGln1 in vitro
Authors: Lapointe J , Duplain L , Proulx M
Published: November 2016

In the presence or absence of its regulatory factor, the monomeric glutamyl-tRNA synthetase from Bacillus subtilis can aminoacylate in vitro with glutamate both tRNAGlu and tRNAGln from B. subtilis and tRNAGln1 but not tRNAGln2 or tRNAGlu from Escherichia coli. The Km and Vmax values of the enzyme for its substrates in these homologous or heterologous aminoacylation reactions are very similar. This enzyme is the only aminoacyl-tRNA synthetase reported to aminoacylate with normal kinetic parameters two tRNA species coding for different amino acids and to misacylate at a high rate a heterologous tRNA under normal aminoacylation conditions. The exceptional lack of specificity of this enzyme for its tRNAGlu and tRNAGln substrates, together with structural and catalytic peculiarities shared with the E. coli glutamyl- and glutaminyl-tRNA synthetases, suggests the existence of a close evolutionary linkage between the aminoacyl-tRNA synthetases specific for glutamate and those specific for glutamine. A comparison of the primary structures of the three tRNAs efficiently charged by the B. subtilis glutamyl-tRNA synthetase with those of E. coli tRNAGlu and tRNAGln2 suggests that this enzyme interacts with the G64-C50 or G64-U50 in the T psi stem of its tRNA substrates.
Highly mobile DNA segment of IncI alpha plasmid R64: a clustered inversion region
Authors: Komano T , Kubo A , Kayanuma T , Furuichi T , Nisioka T
Published: November 2016

When R64 DNA was digested with EcoRI, two DNA fragments not equimolar to the plasmid DNA were produced. A DNA region including these fragments was cloned (pKK009), and the pKK009 DNA sample was found to be a mixture of six or more DNA species with EcoRI, PstI, and AvaI cleavage sites at different positions, suggesting a complex rearrangement of DNA. When a part of the pKK009 DNA was removed by HindIII digestion, 33 different types of plasmids (pKK010-series plasmids) were obtained out of 58 clones tested, but no DNA rearrangement could be observed. On the basis of a comparison of the detailed restriction maps of these pKK010-series plasmids, we propose a model in which four DNA segments invert independently or in groups within the 1.95-kilobase region of R64, so that the arrangements of these four segments change randomly. The fixed pKK010-series plasmid DNA was again rearranged in the presence of R64, indicating that trans-acting gene function may be present to mediate the DNA rearrangement. The gene (tentatively designated as rci) was located on a 4.5-kilobase E9' fragment of R64.
Occurrence of small Hsd plasmids in Salmonella typhi, Shigella boydii, and Escherichia coli
Authors: Yoshida Y , Mise K
Published: November 2016

The natural occurrence of small Hsd (host specificity for DNA) plasmids was demonstrated in restriction endonuclease-producing strains of Salmonella typhi, Shigella boydii, and Escherichia coli. The five Hsd plasmids isolated were between 5.0 and 12.2 kilobases long. The copy number of all the Hsd plasmids was high (more than 10 copies per cell). Introduction of these small plasmids into E. coli strain 0 drastically lowered the efficiency of plating of the lambda.0 phages (the efficiency of plating was less than 5 X 10(-5) PFU-1). High restriction endonuclease activities were detected in the Hsd plasmid-positive strains because of the elevated copy numbers of the hsdR+ gene. The advantages of using E. coli strains containing the small Hsd plasmids for purification of type II restriction endonucleases are discussed.
Sensitivity of a Salmonella typhimurium aspC mutant to sulfometuron methyl, a potent inhibitor of acetolactate synthase II
Authors: Van Dyk T K , LaRossa R A
Published: November 2016

Sulfometuron methyl is a potent and specific inhibitor of acetolactate synthase II in Salmonella typhimurium. Mutant strains sensitive to sulfometuron methyl on minimal medium were isolated following mutagenesis with Tn10. A conditionally auxotrophic insertion mutant, strain SMS409, which required aspartate at high temperatures or in the presence of tyrosine, was found among the 15 mutants isolated. The Tn10 insertion in strain SMS409 was mapped by conjugation and transduction to the region between aroA and pncB at 20 min on the chromosome of S. typhimurium; this location is similar to the genetic location of aspC in Escherichia coli. The specific activity of the aspC product, aspartate aminotransferase, was severely reduced in strain SMS409. This indicated that the Tn10 insertion in strain SMS409 inactivated aspC. An aspC mutant of E. coli was also inhibited by either sulfometuron methyl or tyrosine. We present a hypothesis which relates the observed alpha-ketobutyrate accumulation in sulfometuron methyl-inhibited cultures of strain SMS409 to aspartate starvation.
Regulation of peptide transport in Escherichia coli: induction of the trp-linked operon encoding the oligopeptide permease
Authors: Andrews J C , Blevins T C , Short S A
Published: November 2016

Growth of Escherichia coli in medium containing leucine results in increased entry of exogenously supplied tripeptides into the bacterial cell. This leucine-mediated elevation of peptide transport required expression of the trp-linked opp operon and was accompanied by increased sensitivity to toxic tripeptides, by an enhanced capacity to utilize nutritional peptides, and by an increase in both the velocity and apparent steady-state level of L-[U-14C]alanyl-L-alanyl-L-alanine accumulation for E. coli grown in leucine-containing medium relative to these parameters of peptide transport measured with bacteria grown in media lacking leucine. Direct measurement of opp operon expression by pulse-labeling experiments demonstrated that growth of E. coli in the presence of leucine resulted in increased synthesis of the oppA-encoded periplasmic binding protein.
Camphor revisited: studies of 2,5-diketocamphane 1,2-monooxygenase from Pseudomonas putida ATCC 17453
Authors: Taylor D G , Trudgill P W
Published: November 2016

The oxygenating component of 2,5-diketocamphane 1,2-monooxygenase from Pseudomonas putida ATCC 17453 was purified to homogeneity by a combination of ammonium sulfate fractionation and chromatography on DEAE-cellulose and polyanion SI-17 columns. It had an Mr of 78,000, bound one molecule of nonautooxidizable flavin mononucleotide (FMN), consisted of two subunits of equal molecular weight, and existed in two electrophoretically distinguishable active forms. The oxygenating complex was constructed from equimolecular amounts of an NADH oxidase, which could be purified separately (Mr, 36,000), and the oxygenating component. Most of the NADH oxidase dissociated from the oxygenating component during purification, although traces remained, to give the final preparation of the oxygenating component significant oxygenase activity. FMN did not dissociate significantly from the oxygenating component during purification, but it was not covalently bound and could be removed under a variety of conditions. Binding between the two proteins that made up the active complex was fairly weak and freely reversible. It probably occurred through the FMN which was strongly bound to the oxygenating component and for which the NADH had a weak binding site. Iron was not present at a significant level in the oxygenating component, and in common with other characterized Baeyer Villiger monooxygenases, 2,5-diketocamphane 1,2-monooxygenase was found to be a simple flavoprotein.
Gene amplification induces mucoid phenotype in rec-2 Pseudomonas aeruginosa exposed to kanamycin
Authors: Deretic V , Tomasek P , Darzins A , Chakrabarty A M
Published: November 2016

Gene amplification in the chromosome of rec-2 Pseudomonas aeruginosa PAO2003 upon growth on kanamycin-supplemented media led to a stable mucoid phenotype. The chromosomal region controlling alginate biosynthesis was shown to be amplified four to six times as a direct tandem repeat of at least 16.8 kilobase pairs. This amplification was deduced from Southern DNA-DNA hybridization patterns of the chromosomal DNA digested with restriction endonucleases BglII and EcoRI and probed with a cloned DNA segment complementing the alg-22 mutation. The part of the amplified unit carrying the novel DNA joint was cloned. The EcoRI junction fragment was further subcloned and used to probe chromosomes of parental strain PAO2003 and mucoid variant VD2003M. As predicted, the EcoRI junction fragment hybridized to the two chromosomal fragments required to produce the novel junction. Though the mucoid phenotype caused by gene amplification was stable, nonmucoid revertants were obtained at a low frequency on tetracycline-containing media. Southern hybridization of chromosomal DNA from a nonmucoid revertant revealed a reduction in the copy number of amplified DNA. These results suggest a direct relationship between amplification of this chromosomal segment and the induction of mucoidy.