997 resultados para Tolerance class
Resumo:
Programmed cell death-associated genes, especially antiapoptosis-related genes have been reported to confer tolerance to a wide range of biotic and abiotic stresses in dicotyledonous plants such as tobacco (Nicotiana tabacum L.) and tomato (Solanum lycopersicum L.). This is the first time the antiapoptotic gene SfIAP was transformed into a monocotyledonous representative: rice (Oryza sativa L.). Transgenic rice strains expressing SfIAP were generated by the Agrobacterium-mediated transformation method and rice embryogenic calli, and assessed for their ability to confer tolerance to salt stress at both the seedling and reproductive stages using a combination of molecular, agronomical, physiological and biochemical techniques. The results show that plants expressing SfIAP have higher salt tolerance levels in comparison to the wild-type and vector controls. By preventing cell death at the onset of salt stress and maintaining the cell membrane’s integrity, SfIAP transgenic rice plants can retain plant water status, ion homeostasis, photosynthetic efficiency and growth to combat salinity successfully.
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This study examined questions concerning differences in the acyl composition of membrane phospholipids that have been linked to the faster rates of metabolic processes in endotherms versus ectotherms. In liver, kidney, heart and brain of the ectothermic reptile, Trachydosaurus rugosus, and the endothermic mammal, Rattus norvegicus, previous findings of fewer unsaturates but a greater unsaturation index (UI) in membranes of the mammal versus those of the reptile were confirmed. Moreover, the study showed that the distribution of phospholipid head-group classes was similar in the same tissues of the reptile and mammal and that the differences in acyl composition were present in all phospholipid classes analysed, suggesting a role for the physical over the chemical properties of membranes in determining the faster rates of metabolic processes in endotherms. The most common phosphatidylcholine (PC) molecules present in all tissues (except brain) of the reptile were 16:0/18:1, 16:0/18:2, 18:0/18:2, 18:1/18:1 and 18:1/18:2, whereas arachidonic acid (20:4), containing PCs 16:0/ 20: 4, 18: 0/ 20: 4, were the common molecules in the mammal. The most abundant phosphatidylethanolamines ( PE) used in the tissue of the reptile were 18:0/18:2, 18:0/20:4, 18:1/18:1, 18:1/18:2 and 18:1/20:4, compared to 16: 0/ 18: 2, 16: 0/ 20: 4, 16: 0/ 22: 6, 18: 0/ 20: 4, 18: 0/ 22: 6 and 18:1/20: 4 in the mammal. UI differences were primarily due to arachidonic acid found in both PC and PEs, whereas docosahexaenoic acid (22:6) was a lesser contributor mainly within PEs and essentially absent in the kidney. The phospholipid composition of brain was more similar in the reptile and mammal compared to those of other tissues.
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One DDT-contaminated soil and two uncontaminated soils were used to enumerate DDT-resistant microbes (bacteria, actinomycetes and fungi) by using soil dilution agar plates in media either with 150 μg DDT ml -1 or without DDT at different temperatures (25, 37 and 55°C). Microbial populations in this study were significantly (p<0.001) affected by DDT in the growth medium. However, the numbers of microbes in long-term contaminated and uncontaminated soils were similar, presumably indicating that DDT-resistant microbes had developed over a long time exposure. The tolerance of isolated soil microbes to DDT varied in the order fungi>actinomycetes>bacteria. Bacteria from contaminated soil were more resistant to DDT than bacteria from uncontaminated soils. Microbes isolated at different temperatures also demonstrated varying degrees of DDT resistance. For example, bacteria and actinomycetes isolated at all incubation temperatures were sensitive to DDT. Conversely fungi isolated at all temperatures were unaffected by DDT.
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Historically, class has been a key concern in studies of resource affected communities (e.g., Williamson 1982, Warwick and Littlejohn 1992). While work continues, particularly in Britain, today it reflects the rationalization of the British mining sector, and thus focuses largely on mining heritage (e.g., Strangleman et al. 1999, Dicks 2008). In contrast, this chapter examines class relations as manifest in a contemporary setting in rural Australia. This site, the Ravensthorpe Shire in the south west of Western Australia, relied largely on agriculture until 2004 when BHP Billiton commenced construction of a nickel mine in the area. This affected the entire Shire as well as the two rural communities of Ravensthorpe and Hopetoun. The mine, which was officially opened in June 2008, is one of a large number of new mineral and energy developments being established in non metropolitan areas of the country as high international demand for resources fuels significant growth in the sector. In a single six month period in 2009, for example, 15 major minerals and energy projects were completed across the nation and a further 74 projects were at advanced stages (Australian Bureau of Agricultural Economics 2009). A number of these were, as was the case in Ravensthorpe, in what had been traditionally agricultural communities.
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Rice, an important crop that feeds more than half of the world's population is very sensitive to salinity stress – a growing problem affecting crop production globally. This PhD study addressed this problem by manipulating the programmed cell death pathways in rice resulting in significant enhancement of salinity stress tolerance. The impact of this work is that farmers would be in a position to grow rice containing such a trait in environments where salinisation of the soil exists, thereby addressing food security needs.
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This thesis studied the emotional climate (EC) of a pre-service science teachers' class in Bhutan. It examined the types of activities students engaged in and the relationship between the tutor and students whose interactions produced both positive and negative EC in the class. The major finding was that the activities involving students' presentations using video clips and models, group activity, and coteaching valenced the class EC positively. Negative EC was identified when the tutor ignored students' responses, during formal lectures, and when the tutor was uncertain of the subject knowledge. The replication of activities that produce positive EC by other Bhutanese tutors may improve the standard of science education in the country.
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This study investigates the governance attributes of firms that have been subject to securities class actions (SCAs). There has been a recent sizable increase in the number of firms subject to SCAs in Australia. We examine a sample of firms that have been subject to SCAs due to disclosure breaches and match the firms by industry and size to a control sample. First, we examine the compliance culture of the SCA firms via the frequency of Australian Securities Exchange (ASX)queries of the firm and find that the frequency of ASX queries is positively associated with the occurrence of a SCA. Secondly, we provide evidence that SCA firms exhibit weaker levels of corporate governance than the matched control sample. In addition, we contribute to the understanding of firms subject to SCAs and their corporate governance attributes. Our results suggest the presence of a nomination committee may be associated with higher agency costs and that the influence of CEO duality may reduce the effectiveness of a nomination committee.
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Salinity is a major threat to sustainable agriculture worldwide. Plant NHX exchangers play an important role in conferring salt tolerance under salinity stress. In this study, a vacuolar Na+/H+ antiporter gene VrNHX1 (Genbank Accession No. JN656211.1) from mungbean (Vigna radiata) was introduced into cowpea (Vigna unguiculata) by the Agrobacterium tumefaciens-mediated transformation method. Polymerase chain reaction and Southern blot hybridization confirmed the stable integration of VrNHX1 into the cowpea genome. Comparative expression analysis by semi-quantitative RT-PCR revealed higher expression of VrNHX1 in transgenic cowpea plants than wild-type. Under salt stress conditions, T2 transgenic 35S:VrNHX1 cowpea lines exhibited higher tolerance to 200 mM NaCl treatment than wild-type. Furthermore, T2 transgenic 35S:VrNHX1 lines maintained a higher K+/Na+ ratio in the aerial parts under salt stress and accumulated higher [Na+] in roots than wild-type. Physiological analysis revealed lower levels of lipid peroxidation, hydrogen peroxide and oxygen radical production but higher levels of relative water content and proline, ascorbate and chlorophyll contents in T2 transgenic 35S:VrNHX1 lines.
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In the context of the first-year university classroom, this paper develops Vygotsky’s claim that ‘the relations between the higher mental functions were at one time real relations between people’. By taking the main horizontal and hierarchical levels of classroom discourse and dialogue (student-student, student-teacher, teacher-teacher) and marrying these with the possibilities opened up by Laurillard’s conversational framework, we argue that the learning challenge of a ‘troublesome’ threshold concept might be met by a carefully designed sequence of teaching events and experiences for first year students, and we provide a number of strategies that exploit each level of these ‘hierarchies of discourse’. We suggest that an analytical approach to classroom design that embodies these levels of discourse in sequenced dialogic methods could be used by teachers as a strategy to interrogate and adjust teaching-in-practice especially in the first year of university study.
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The question concerning what makes for good BPM is often raised. A recent call from Paul Harmon on the BPTrends Discussion LinkedIN Group for key issues in BPM received 189 answers within two months, with additional answers still appearing. I have teamed up with a number of BPM researchers and practitioners to bring together our joint experience in a BPM workshop at the University in Liechtenstein in 2013, where we developed ten principles of good BPM, later published in Business Process Management Journal (vom Brocke et al., 2014). The paper, which has received considerable attention in academia, was ranked the journal’s most downloaded paper the month it was published. Slides on Slideshare that provide a brief summary of the paper have been accessed more than 3,000 times since they were first put online in March 2014. Given the importance of the topic–what makes for good BPM–and the positive response to the ten principles, I wrote this note with the co-authors of the original BPMJ paper to outline the ten principles and illustrate how to use them in practice. We invite all readers to engage in this discussion via any channel they find appropriate.
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Conjugation of chemicals with glutathione (GSH) can lead to decreased or increased toxicity. A genetic deficiency in the GSH S-transferase μ class gene M1 has been hypothesized to lead to greater risk of lung cancer in smokers. Recently a gene deletion polymorphism involving the human θ enzyme T1 has been described; the enzyme is present in erythrocytes and can be readily assayed. A rat θ class enzyme, 5-5, has structural and catalytic similarity and the protein was expressed in the Salmonella typhimurium tester strain TA1535. Expression of the cDNA vector increased the mutagenicity of ethylene dibromide and several methylene dihalides. Mutations resulting from the known GSH S-transferase substrate 1,2-epoxy-3-(4′nitrophenoxy)propane were decreased in the presence of the transferase. Expression of transferase 5-5 increased mutations when 1,2,3,4-diepoxybutane (butadiene diepoxide), 4-bromo-1,2-epoxybutane, or 1,3-dichloracetone were added. The latter compound is a model for the putative 1,2-dibromo-3-chloropropane oxidation product 1-bromo-3-chloroacetone. These genotoxicity and genotyping assays may be of use in further studies of the roles of GSH S-transferase θ enzymes in bioactivation and detoxication and any changes in risk due to polymorphism.
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The presence of theta-class glutathione S-transferase (GST) in marmoset monkey liver cytosol was investigated. An anti-peptide antibody targeted against the C-terminus of rGSTT1 reacted with a single band in marmoset liver cytosol that corresponded to a molecular weight of 28 kDa. The intensity of the immunoreactive band was not affected by treatment of marmoset monkeys with 2,3,7,8-tetrachlorodibenzo-p-dioxin, phenobarbitone, rifampicin or clofibric acid. Similarly, activity towards methyl chloride (MC) was unaffected by these treatments. However, GST activity towards 1,2-epoxy3-(p- nitrophenoxy)-propane (EPNP) was increased in marmosets treated with phenobarbitone (2.6-fold) and rifampicin (2.6-fold), activity towards dichloromethane (DCM) was increased by 50% after treatment of marmosets with clofibric acid, and activity towards 1-chloro-2,4-dinitrobenzene (CDNB) was raised slightly (30-42% increases) after treatment with phenobarbitone, rifampicin or clofibric acid. Compared with humans, marmoset liver cytosol GST activity towards DCM was 18-fold higher, activity towards MC was 7 times higher and activity towards CDNB was 4 times higher. Further, EPNP activity was clearly detectable in marmoset liver cytosol samples, but was undetectable in human samples. Immunoreactive marmoset GST was partially purified by affinity chromatography using hexylglutathione-Sepharose and Orange A resin. The interaction of immunoreactive marmoset GST was similar to that found previously for rat and human GSTT1, suggesting that this protein is also a theta class GST. However, unlike rat GSTT1, the marmoset enzyme was not the major catalyst of EPNP conjugation. Instead, immunoreactivity was closely associated with activity towards MC. In conclusion, these results provide evidence for the presence of theta-class GST in the marmoset monkey orthologous to rGSTT1 and hGSTT1.
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This study evaluated the physiological tolerance times when wearing explosive and chemical (>35kg) personal protective equipment (PPE) in simulated environmental extremes across a range of differing work intensities. Twelve healthy males undertook nine trials which involved walking on a treadmill at 2.5, 4 and 5.5 km.h-1 in the following environmental conditions, 21, 30 and 37 °C wet bulb globe temperature (WBGT). Participants exercised for 60 min or until volitional fatigue, core temperature reached 39 °C, or heart rate exceeded 90% of maximum. Tolerance time, core temperature, skin temperature, mean body temperature, heart rate and body mass loss were measured. Exercise time was reduced in the higher WBGT environments (WBGT37
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This paper presents Rolling Stone Indonesia (RSI) and places it in an historical context to tease out some changes and continuities in Indonesian middle-class politics since the beginning of the New Order. Some political scientists have claimed that class interests were at the core of the transition from Guided Democracy to the New Order, and popular music scholars generally assert that class underlies pop genre distinctions. But few have paid attention to how class and genre were written into Indonesian pop in the New Order period; Indonesian pop has a fascinating political history that has so far been overlooked. Placing RSI in historical perspective can reveal much about the print media’s classing of pop under New Order era political constraints, and about the ways these modes of classing may or may not have endured in the post-authoritarian, globalised and liberalised media environment.