924 resultados para Herbicide retention
Resumo:
Chloroplast-targeted overexpression of an Fe superoxide dismutase (SOD) from Arabidopsis thaliana resulted in substantially increased foliar SOD activities. Ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were similar in the leaves from all of the lines, but dehydroascorbate reductase activity was increased in the leaves of the FeSOD transformants relative to untransformed controls. Foliar H2O2, ascorbate, and glutathione contents were comparable in all lines of plants. Irradiance-dependent changes in net CO2 assimilation and chlorophyll a fluorescence quenching parameters were similar in all lines both in air (21% O2) and at low (1%) O2. CO2-response curves for photosynthesis showed similar net CO2-exchange characteristics in all lines. In contrast, values of photochemical quenching declined in leaves from untransformed controls at intercellular CO2 (Ci) values below 200 μL L−1 but remained constant with decreasing Ci in leaves of FeSOD transformants. When the O2 concentration was decreased from 21 to 1%, the effect of FeSOD overexpression on photochemical quenching at limiting Ci was abolished. At high light (1000 μmol m−2 s−1) a progressive decrease in the ratio of variable (Fv) to maximal (Fm) fluorescence was observed with decreasing temperature. At 6oC the high-light-induced decrease in the Fv/Fm ratio was partially prevented by low O2 but values were comparable in all lines. Methyl viologen caused decreased Fv/Fm ratios, but this was less marked in the FeSOD transformants than in the untransformed controls. These observations suggest that the rate of superoxide dismutation limits flux through the Mehler-peroxidase cycle in certain conditions.
Resumo:
Dichloroacetamide safeners protect maize (Zea mays L.) against injury from chloroacetanilide and thiocarbamate herbicides. Etiolated maize seedlings have a high-affinity cytosolic-binding site for the safener [3H](R,S)-3-dichloroacetyl-2,2,5-trimethyl-1,3-oxazol-idine ([3H]Saf), and this safener-binding activity (SafBA) is competitively inhibited by the herbicides. The safener-binding protein (SafBP), purified to homogeneity, has a relative molecular weight of 39,000, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and an isoelectric point of 5.5. Antiserum raised against purified SafBP specifically recognizes a 39-kD protein in etiolated maize and sorghum (Sorghum bicolor L.), which have SafBA, but not in etiolated wheat (Triticum aestivum L.), oat (Avena sativa L.), barley (Hordeum vulgare L.), tobacco (Nicotiana tabacum L.), or Arabidopsis, which lack SafBA. SafBP is most abundant in the coleoptile and scarcest in the leaves, consistent with the distribution of SafBA. SBP1, a cDNA encoding SafBP, was cloned using polymerase chain reaction primers based on purified proteolytic peptides. Extracts of Escherichia coli cells expressing SBP1 have strong [3H]Saf binding, which, like binding to the native maize protein, is competitively inhibited by the safener dichlormid and the herbicides S-ethyl dipropylthiocarbamate, alachlor, and metolachlor. SBP1 is predicted to encode a phenolic O-methyltransferase, but SafBP does not O-methylate catechol or caffeic acid. The acquisition of its encoding gene opens experimental approaches for the evaluation of the role of SafBP in response to the relevant safeners and herbicides.
Resumo:
(+)-Hydantocidin, a recently discovered natural spironucleoside with potent herbicidal activity, is shown to be a proherbicide that, after phosphorylation at the 5' position, inhibits adenylosuccinate synthetase, an enzyme involved in de novo purine synthesis. The mode of binding of hydantocidin 5'-monophosphate to the target enzyme was analyzed by determining the crystal structure of the enzyme-inhibitor complex at 2.6-A resolution. It was found that adenylosuccinate synthetase binds the phosphorylated compound in the same fashion as it does adenosine 5'-monophosphate, the natural feedback regulator of this enzyme. This work provides the first crystal structure of a herbicide-target complex reported to date.
Resumo:
Mutations in the human phosphofructokinase muscle subunit gene (PFKM) are known to cause myopathy classified as glycogenosis type VII (Tarui disease). Previously described molecular defects include base substitutions altering encoded amino acids or resulting in abnormal splicing. We report a mutation resulting in phosphofructokinase deficiency in three patients from an Ashkenazi Jewish family. Using a reverse transcription PCR assay, PFKM subunit transcripts differing by length were detected in skeletal muscle tissue of all three affected subjects. In the longer transcript, an insertion of 252 nucleotides totally homologous to the structure of the 10th intron of the PFKM gene was found separating exon 10 from exon 11. In addition, two single base transitions were identified by direct sequencing: [exon 6; codon 95; CGA (Arg) to TGA (stop)] and [exon 7; codon 172; ACC (Thr) to ACT (Thr)] in either transcript. Single-stranded conformational polymorphism and restriction enzyme analyses confirmed the presence of these point substitutions in genomic DNA and strongly suggested homozygosity for the pathogenic allele. The nonsense mutation at codon 95 appeared solely responsible for the phenotype in these patients, further expanding genetic heterogeneity of Tarui disease. Transcripts with and without intron 10 arising from identical mutant alleles probably resulted from differential pre-mRNA processing and may represent a novel message from the PFKM gene.
Resumo:
The intent of the study was to understand the changes that have occurred over the last 25 years in library programs as far as enrollment and diversity of students, number and ethnicity of the faculty, program income and expenses, cost of attendance, and scholarship and fellowship aid, in an effort to better understand library programs granting the MLIS degree. The study also endeavored to identify institutional factors associated with the retention and productivity rates of White students and students of color in schools of library and information science. During the period studied, the proportional representation of White students decreased. For students of color, proportional representation was stable during the same time period. Results revealed a medium effect size of time with productivity rates for both groups declining over time. Retention rate differed significantly by time, with a small effect size with retention rate that initially increased over time, but is now decreasing. The final analyses were meta-regressions to determine if retention and productivity rates can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicated that for students of color, program size in 2000 was significantly predictive of retention, cost of attendance was predictive in 2002, and scholarship and fellowship aid was predictive of retention in 2004. No variables were significantly predictive for retention of White students. The last analysis was to determine if productivity rate can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicate that for White students in 2002, the cost of attendance was predictive of productivity rating. In 2003, scholarship and fellowship aid was predictive of productivity rate and in 2004, scholarship and fellowship aid was predictive of productivity rating. For students of color, results indicate that only scholarship and fellowship aid in 2005 was predictive of productivity rate. No other variables in any of the years studied showed any significant prediction of productivity rating for students of color.
Resumo:
The Journal Retention and Needs Listing (JRNL) program: 1) allows libraries to expose lists of print journals for which they have made retention commitments; 2) express needs (or gaps) in their holdings; and 3) communicate offers to fill the gaps in other participating libraries’ holdings. Multiple library consortia and their member libraries use JRNL to facilitate communication between library staff to identify holding commitments, fill gaps, and guide deselection decisions. JRNL is commonly developed and governed by the participating consortia. Currently, those consortia are the Florida Academic Repository (FLARE), the Association of Southeastern Research Libraries (ASERL)/Washington Research Library Consortium (WRLC), and the Western Regional Storage Trust (WEST).
Resumo:
Weed control in recreation areas is a complex public land management issue. Colorado State Parks are managed for both recreation and conservation, which often conflict. Noxious weeds affect both recreation and conservation efforts, and Parks often use herbicides to control these weeds. While herbicides are effective, they can be harmful to the environment and human health. Herbicide use at State Parks was reviewed to determine if chemical control is effective, safe, and efficient. The results revealed that many Parks are not using effective herbicides to treat noxious weeds and that some weed management plans lack pertinent information on chemical control. The results and recommendations provided can be used to improve the success of noxious weed control and create healthier Parks.
Resumo:
An economic recession affects the ability of organizations to retain employees. The downturn in the economy causes employers to evaluate how they conduct business causing lay-offs and unemployment rates to rise during periods of recession. A retention strategy is as important as sales and customer service during an economic recession. The impact of decisions made during the recession and the imminent labor shortage will impact the ability of organizations to retain their high performing employees. The author details the areas organizations must consider in a retention strategy and develops a retention model for her employer that can be used to assist with reducing turnover as the economy and the labor force begins to change.
Resumo:
In the latter half of the twentieth century the workforce dynamic changed when the number of women entering the workforce increased by record amounts. In direct opposition to this change was the inability of organizations to meet the needs of employees with childcare concerns. Organizations and employees alike are best served when policies, procedures, and benefits are implemented to achieve a positive work/life balance. Companies that institute benefits that are supportive to families observe decreases in turnover and increased employee retention. Employees who are offered family friendly resources have been known to stay with companies even when offered a higher salary elsewhere. Demonstrating that retention of valued employees is linked to an organizations ability to offer support for family needs.
Resumo:
In this study, the filtration process and the biomass characteristics in a laboratory-scale submerged membrane bioreactor (MBR) equipped with a hollow fiber (HF) microfiltration membrane were studied at different solid retention times (SRT). The MBR was fed by synthetic wastewater and the organic loading rate (OLR) was 0.5, 0.2, 0.1, and 0.08 kg COD kg VSS−1 d−1 for 10, 30, 60, and 90 days of SRT, respectively. The hydraulic retention time was 8.4 h and the permeate flux was 6 L m−2 h−1(LMH). Data analysis confirmed that at all the studied SRTs, the HF-MBR operated very good obtaining of high quality permeates. Chemical Oxygen Demand (COD) removal efficiencies were higher than 95%. The best filtration performance was reached at SRT of 30 d. On the other hand, the respirometric analysis showed that biomass was more active and there was more biomass production at low SRTs. The concentration of soluble extracellular polymeric substances (EPS) decreased with increasing SRT. A decrease of soluble EPS caused a decrease of membrane fouling rate, decreasing the frequency of chemical cleanings. The floc size decreased with SRT increasing. At high SRTs, there was more friction among particles due to the increase of the cellular density and the flocs broke decreasing their size.
Resumo:
This paper examines the challenges facing the EU regarding data retention, particularly in the aftermath of the judgment Digital Rights Ireland by the Court of Justice of the European Union (CJEU) of April 2014, which found the Data Retention Directive 2002/58 to be invalid. It first offers a brief historical account of the Data Retention Directive and then moves to a detailed assessment of what the judgment means for determining the lawfulness of data retention from the perspective of the EU Charter of Fundamental Rights: what is wrong with the Data Retention Directive and how would it need to be changed to comply with the right to respect for privacy? The paper also looks at the responses to the judgment from the European institutions and elsewhere, and presents a set of policy suggestions to the European institutions on the way forward. It is argued here that one of the main issues underlying the Digital Rights Ireland judgment has been the role of fundamental rights in the EU legal order, and in particular the extent to which the retention of metadata for law enforcement purposes is consistent with EU citizens’ right to respect for privacy and to data protection. The paper offers three main recommendations to EU policy-makers: first, to give priority to a full and independent evaluation of the value of the data retention directive; second, to assess the judgment’s implications for other large EU information systems and proposals that provide for the mass collection of metadata from innocent persons, in the EU; and third, to adopt without delay the proposal for Directive COM(2012)10 dealing with data protection in the fields of police and judicial cooperation in criminal matters.