Browsing by Subject "Tobacco"
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Item Analysis of transgenic tobacco that express maize catalase3(Texas Tech University, 1999-05) Schake, Sheryl A.Catalases (H2O2: H2O2 oxidoreductase, EC 1.11.1.6; CAT) are hemecontaining tetramers that are important in destroying H2O2 found in different cellular compartments. Maize Cats has been shown to be capable of dismutating H2O2 via either a catalatic or peroxidatic reaction. In addition, increased maize CAT3 transcripts were detected during periods of chilling acclimation. In this study, a maize CatS cDNA was isolated using reverse transcriptase polymerase chain reaction. To better understand the role of maize CAT3 in oxidative stress, we have introduced the transgene that expresses this enzyme into wild type Xanthi NN tobacco (Nicotiana tabacum). Total catalase activities were only slightly higher in transgenic plants as compared to Xanthi NN. While total peroxidatic activity of these transgenic plants was found to be 12-fold higher than in the wild-type tobacco. Thetransgenic Cat3 plants were exposed to various abiotic stresses such as, low temperatures, high temperatures, salinity, chemical treatments, and photooxidation. Increased seedling growth was evident in transgenic seedlings during treatments at low temperatures, high temperatures, and salinity which could implicate increased protection from oxidative damage. No significant protection was evident when transgenic seedlings were treated with methyl viologen or photooxidatlve stress. In addition, lower lipid peroxidation levels in transgenic plants correlated with increased peroxidatic activity in these plants. These data suggests that in wild-type tobacco that express maize CAT3 have increased protection against various forms of oxidative stress.Item Construction of vectors for the overexpression and inhibition of iron superoxide dismutase in Nicotiana tabacum(Texas Tech University, 1995-08) Cook, William S.Recent advances in plant biotechnology provide scientists with the opportunity to alter crops to meet the needs of society. Research reported in this thesis is the preliminary result of an attempt to genetically engineer plants to resist oxidative stress. Both plants and animals use oxygen as an electron acceptor in oxidative phosphorylation, reducing oxygen to water. Plants also produce oxygen by oxidizing water to provide elecfrons for photosynthesis. The oxidation of water to oxygen during photosynthesis, which requires the transfer of four electrons per oxygen molecule produced, is completed in a single step. Therefore, no reactive oxygen intermediates are produced. High light raises the potential energy of the elecfrons in the photosynthetic pathway, providing reducing power for the elecfron transport chain (reviewed in Bowler et al., 1992). Reactive oxygen intermediates such as superoxide (-02'), hydrogen peroxide (H2O2), and the hydroxyl radical (-OH) are produced when the plant cannot utilize this energy by productive means (such as storing the energy of the elecfrons by using them to produce carbohydrates). The plant must drain the electrons nonproductively. Reactive oxygen intermediates cause cellular damage that is referred to as oxidative stress. During photosynthesis, molecular oxygen competes with nicotinamide adenine dinucleotide phosphate (NADP) for elecfrons from the reduced photosystem. NADP is the primary electron acceptor and is reduced to NADPH, providing reducing power for carbohydrate synthesis. Under stressfiil conditions, including high light and cold temperatures, the Calvin Cycle cannot recycle NADP quickly enough, so that the NADP becomes scarce and the plant reduces O2. A plant under oxidative stress reduces oxygen by a single electron, instead of by four as in oxidative phosphorylation, resulting in a negatively charged oxygen molecule with an unpaired electron. This reactive molecule is the superoxide radical (•O2"). In addition to photosynthesis and respiration, the univalent reduction of oxygen to produce superoxide may result from a variety of biological reactions. These include the oxidation of flavins (Ballou et al, 1969), hydroquinones (Misra and Fridovich, 1972a), catecholamines (Cohen and Heikkila, 1974), thiols (Saez et al, 1982), hemoglobin (Misra and Fridovich, 1972b) and reduced ferredoxin (Misra and Fridovich, 1971). Several oxidative enzymes can also produce superoxide including xanthine oxidase, aldehyde oxidase, and several flavin dehydrogenases (reviewed by Fridovich, 1975). Also, neutrophils and macrophages produce toxic concentrations of superoxide during phagocytosis in response to infection (Bannister and Bannister, 1985).Item Expression of a cotton fiber "specific" gene promoter in tobacco and cotton(Texas Tech University, 1996-05) Dang, Phat M.Cotton fibers {Gossypiuiv hirsutum L.) are highly elongated trichomes that grow from epidermal cells of cotton ovules. Analysis of genes that are specifically expressed during fiber differentiation can provide insights into the molecular events that control cotton fiber development. One such gene, called Gh-1, has been isolated and characterized. Deletion analysis of the 5' flanking sequences of the Gh-1 gene was performed to identify the putative regulatory elements responsible for fiber specific expression. The Gh-1 promoter, along with various lengths of 5' flanking sequences, were fused with the p-glucuronidase (GUS) reporter gene and transferred into tobacco and cotton plants via /\gro/)acter/aAr7-mediated transformation. Tobacco plants that carry the Gh-1::GUS gene construct with 965 bp of 5' flanking sequence (-965) from the putative transcription start site typically showed very weak GUS activity in vascular tissues and guard cells, and, in some plants, expression was seen in small glandular trichomes. Similar expression patterns were also seen in plants that carried -735, and -635 Gh-1::GUS promoter constructs. A dramatic increase in specific expression in large glandular trichomes was observed in plants that carried a -500 Gh-1::GUS promoter construct. Promoter deletion constructs -305 Gh-1::GUS or shorter showed no observable GUS staining. Cotton plants single cell line #41 carrying the -965 Gh-1::GUS construct showed no observable GUS staining in stem and 0-3 DPA ovules. However, promoter deletion -500 Gh-1::GUS construct single cell line #22 showed strong GUS staining in guard cells and glandular trichomes in the stem and staining in 0-3 DPA ovules. These results indicated that a trichome and guard cell "specific" regulatory element apparently exist between -500 and -305 of the Gh-1 promoter.Item Factors related to nurses smoking behavior(2005-05) Marchildon, Janice G.; Owen, Donna; Saunders, Jana; Andersen, SusanNurses, as the largest professional group in healthcare, have tremendous influence in the promotion of health, particularly as it relates to smoking. Smoking is considered to be the most important avoidable cause of chronic ill health in the world and several studies have found that many nurses smoke; which not only places their own health at risk, but also the publics (Piko, 2002; Hawkins, White & Morris, 1982; Booth & Faulkner, 1986). The purpose of this research was to describe nurses’ experiences with smoking as well as describe their smoking behavior in relation to demographics and socio-psychological influence. The relationship between smoking and the nurses’ perceived role in health promotion was also described in this research. The theoretical framework for this proposed study is Simmons (1990) Health Promotion Self Care System Model (HPSCSM). This model integrates the constructs of Pender’s Health Promotion Model, Orem’s Self-care Deficit Theory and Cox’s Interaction Model of Client Health Behavior. The study design was descriptive correlational. A convenience sample of 196 nurses employed in a variety of patient care settings within an urban medical center was used for this study. Data collection included a revised version of the Oncology Nurses and Tobacco Control Survey (Sarna, et al., 2000). Descriptive and inferential statistics that include Chi Square analysis was used to address four research questions. The description of nurses’ experiences with smoking in this sample showed that 68 (34.7%) reported that they had smoked at least 100 cigarettes in their lifetime and 39 (19.9%) reported current smoking. Among the demographic factors, the level of nursing education was positively correlated with current smoking behavior. Among the socio-psychological factors, stress was rated highest in importance by current smokers. More non-smokers and former smokers, compared to current smokers, felt positively about nurses serving as role models by not smoking.Item Factors related to nurses smoking behavior(Texas Tech University, 2005-05) Marchildon, Janice G.; Owen, Donna; Saunders, Jana; Andersen, SusanNurses, as the largest professional group in healthcare, have tremendous influence in the promotion of health, particularly as it relates to smoking. Smoking is considered to be the most important avoidable cause of chronic ill health in the world and several studies have found that many nurses smoke; which not only places their own health at risk, but also the publics (Piko, 2002; Hawkins, White & Morris, 1982; Booth & Faulkner, 1986). The purpose of this research was to describe nurses’ experiences with smoking as well as describe their smoking behavior in relation to demographics and socio-psychological influence. The relationship between smoking and the nurses’ perceived role in health promotion was also described in this research. The theoretical framework for this proposed study is Simmons (1990) Health Promotion Self Care System Model (HPSCSM). This model integrates the constructs of Pender’s Health Promotion Model, Orem’s Self-care Deficit Theory and Cox’s Interaction Model of Client Health Behavior. The study design was descriptive correlational. A convenience sample of 196 nurses employed in a variety of patient care settings within an urban medical center was used for this study. Data collection included a revised version of the Oncology Nurses and Tobacco Control Survey (Sarna, et al., 2000). Descriptive and inferential statistics that include Chi Square analysis was used to address four research questions. The description of nurses’ experiences with smoking in this sample showed that 68 (34.7%) reported that they had smoked at least 100 cigarettes in their lifetime and 39 (19.9%) reported current smoking. Among the demographic factors, the level of nursing education was positively correlated with current smoking behavior. Among the socio-psychological factors, stress was rated highest in importance by current smokers. More non-smokers and former smokers, compared to current smokers, felt positively about nurses serving as role models by not smoking.