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Showing 11 to 20 of 20 (0.083 seconds)| 11 |
Monitoring reverse osmosis membrane integrity and virus rejection in water reuse / Effet de l’intégrité de membranes d'osmose inverse sur la rétention de substituts de virusPype, Marie-Laure 18 December 2013 (has links)
Les procédés d'osmose inverse (OI) permettent la production d'eau recyclée de très haute qualité grâce à l'élimination de contaminants organiques et inorganiques et de micro-organismes. Le suivi du bon fonctionnement de ce procédé est nécessaire pour valider la rétention des virus pathogènes afin de protéger la santé des usagers. La présence de minéraux et matières organiques dans les effluents rend inévitable le colmatage des membranes lors de leur fonctionnement et diminue ainsi leur performance. Afin d'éviter et d'éliminer ces colmatages, les stations de traitements des eaux utilisent des produits chimiques. Ces derniers vont modifier les performances globales des membranes en polyamide comme par exemple la diminution de la perméabilité à l'eau, et plus particulièrement les performances de rétention des virus, or l'ensemble de ces perturbations n'est que très peu compris et donc peu maitrisé. L'abattement des virus par l'OI sur des membranes intègres ou modifiées (ex : colmatage) ont donc été déterminés en mesurant la rétention d'un virus modèle de type phage MS2 et de substituts comme les sels (mesurés par conductivité), la rhodamine-WT (R-WT) ou les sulfates. La conductivité est, en effet, la technique de contrôle standard dans les stations de traitement des eaux (échelle industrielle).Le premier objectif de ce travail est d'évaluer l'utilisation d'un autre paramètre, les matières organiques dissoutes (DOM) comme nouveau substitut de virus et de déterminer l'impact du dysfonctionnement des procédés d'OI sur l'abattement des DOM et des sels à l'échelle industrielle. Les DOM peuvent en effet également être utilisées comme indicateur de qualité des eaux en fonction de leurs compositions et de leurs concentrations. L'abattement des DOM est donc testé comme nouvelle technique de surveillance afin de distinguer les fuites des changements de performance des membranes. Il est conclu que les DOM peuvent être utilisées comme nouvelle technique de contrôle. De plus, une variation de l'abattement des DOM peut aider à identifier des fuites de manière plus robuste que par l'abattement des sels. Le deuxième objectif est de déterminer l'effet des défauts membranaires sur les abattements d'un virus modèle (phage MS2) et de quatre substituts (R-WT, DOM, sulfate et sels) à l'échelle de systèmes de laboratoire. Deux systèmes à flux longitudinal est utilisés : une membrane plane et un module à spirale. Dans un premier temps, l'effet du colmatage sur les abattements de ces différents virus et substituts est étudié. Le colmatage organique, créé en utilisant un mélange de matières organiques, a pour effet d'augmenter de plus de 0,1 log les abattements de la R-WT, des sels et des DOM. Cette augmentation générale peut être due au blocage des cavités de la membrane et/ou par la sorption des substituts sur les matières organiques.Le colmatage inorganique, créé en utilisant un mélange de sels, n'a pas d'effet sur le rejet des substituts sauf pour les sels qui montre un comportement différent entre les deux systèmes. Dans le système à membrane plane, la couche inorganique permet d'augmenter le passage des sels à travers la membrane. Par opposition, il n'y a pas d'effet sur leur abattement avec le module à spirale. Cette variation entre les deux systèmes peut être causée par la différence de configuration (module à spirale contre membrane plane). Dans un deuxième temps, l'effet du chlore (modes passif et actif) sur la rétention de ces cinq composés est mesuré. Après un contact de 9000 ppm.h de NaOCl à pH 7, la surface membranaire change chimiquement. La formation de liaison Cl dans la couche en polyamide et la rupture des liaisons NH provoquent l'augmentation de la perméabilité à l'eau et diminuent l'abattement de l'ensemble des substituts. Malgré une forte diminution de 1,2 log de l'abattement en sel, l'abattement minimum du phage MS2 reste de 3 log. / One of the major applications of reverse osmosis (RO) process is the production of high quality recycled water by providing a barrier to remove organic and inorganic contaminants as well as pathogens including viruses. In order to protect public health, validation and monitoring of the RO process integrity are necessary to ensure its correct operation. During operation a certain degree of fouling is inevitable and can reduce RO membrane performance. Thus, chemicals are often used in water treatment plants to prevent or remove the membrane fouling. However, these chemicals can modify the integrity of the polyamide layer on RO membrane overtime. Up-to-date, the impact of membrane's physical change on its virus removal efficiency cause by the chemical use during operation is still not well understood.A minimum virus removal efficiency of intact and impaired (e.g. by fouling) RO membranes can be ascertained by measuring the rejection of MS2 phage and virus surrogates such as salt as measured by conductivity, rhodamine-WT (R-WT) or sulphate. However, conductivity measurement is the only full-scale standard monitoring technique. The removal of dissolved organic matter (DOM), which has been used as an indicator of water quality, can possibly be used for this purpose.The first objective of this work was to assess the suitability of DOM as a virus surrogate and to determine the impact of process failure on salt and DOM rejection in full-scale plants. A change of the conductivity does not necessarily mean that the membrane integrity has been breached. Thus, DOM monitoring has been tested and combined with the conductivity monitoring in order to distinguish between leaks and changes in membrane performances. It was concluded that DOM could be used as new monitoring technique. Moreover, a variation of DOM rejection can help identifying leaks better than just conductivity profiling alone.The second objective was to determine the effect of membrane impairments on the rejection of one model virus (MS2 phage) and four virus surrogates (R-WT, DOM, sulphate and salt) using lab-scale RO set-ups. To this aim, two different cross-flow set-ups were used: a flat-sheet and a single 2.5” spiral-wound module.Firstly, the effects of organic fouling and scaling on the rejection of model virus and virus surrogates were studied separately. Organic fouling was created using a mix of organic foulants. The result of this study showed an increase of the rejection by more than 0.1 log for R-WT, salt and DOM. The general increase of the surrogates' rejection might be due to the blocking of cavities of the polyamide membrane and/or to the sorption of surrogates to the fouling layer, which was observed by different autopsy techniques.Scaling was created using a mix of inorganic salts in order to reconstitute the composition of a RO feed water and avoiding the presence of organic foulants. Scaling was found to have no impact on the rejection of all tested virus surrogates except for salt. Salt rejection showed a change of behaviour between different set-ups: with the 2.5” module set-up the inorganic layer led to a stabilisation of the salt rejection, whereas the salt rejection increased with the flat-sheet set-up. This could be explained by the variations of the systems configuration (i.e. spiral module versus flat-sheet, feed spacer height, etc.).Secondly, the long-term impact of membrane ageing by exposure to chlorine, either active under filtration or passive by soaking, on the rejection of the model virus and four surrogates was studied. After a contact time of 9000 ppm∙h NaOCl at pH 7, the membrane surface chemistry changed. The introduction of chlorine in the membrane chemistry and the breakage of amide bonds caused an increase of the water permeability and a decrease of the model virus and virus surrogates rejection.
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Evaluation of Stallion Sperm Membrane Integrity Using Varied Flow Cytometer-Based MethodologiesStump, Karen Elizabeth 03 October 2013 (has links)
Artificial insemination using cooled, transported semen has become a popular practice in the equine industry. However, equine sperm are assumed to show a decline in their fertilizing ability after 24 to 48 hours of cooled storage. Two measures that are commonly used to estimate the fertility of an ejaculate are sperm motility and sperm membrane integrity (SMI). Recently, it has been suggested that SMI may have a better correlation with fertility of an inseminate than sperm motility. The effect of cooled-storage on sperm quality over an extended time period was evaluated to illustrate changes in sperm characteristics that might be related to an ejaculate’s fertility.
Semen was stored at 4°C in INRA 96 extender containing 10% seminal plasma for a period of 10 days. Data were collected daily on sperm motion characteristics, SMI, mitochondrial membrane potential, and DNA quality. To measure daily changes in SMI in stallion sperm, two fluorescent vital-staining protocols used in flow cytometric analysis were compared – a combination of SNARF-1, Yo-Pro-1, and Ethidium Homodimer 1 (SYE) and a combination of lectin from Pisum sativum and propidium iodide (PSA/PI). We hypothesized that the SYE protocol adapted for use with stallion sperm could detect more subtle, and perhaps earlier, damage to the sperm plasma membrane than the PSA/PI protocol. A combination of SYBR 14, propidium iodide, and JC-1 (SYPIJC) was used to measure mitochondrial membrane potential, as well as SMI. A computer-assisted sperm motion analysis (CASA) instrument was used to evaluate sperm motion characteristics; the sperm chromatin structure assay (SCSA) was used to measure the degree of DNA fragmentation.
In this study, with the exception of sperm motility, the measures of sperm quality retained values consistent with “viability” after 10 days of cooled-storage. This suggests that the fertility of some stallions may last considerably longer than previously assumed, which could ultimately alter the time-table used for artificial insemination using cooled, transported semen.
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Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticasSchlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
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Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticasSchlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
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Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticasSchlindwein, Carolina Casco Duarte January 2012 (has links)
As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.
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Thermotolerance of cottonCottee, Nicola Sandra January 2009 (has links)
Doctor of Philosophy (PhD) / The Australian cotton industry has developed high yielding and high quality fibre production systems and attributes a significant contribution of this achievement to highly innovative breeding programs, specifically focused on the production of premium quality lint for the export market. Breeding programs have recently shifted attention to the development of new germplasm with superior stress tolerance to minimise yield losses attributed to adverse environmental conditions and inputs such as irrigation, fertilisers and pesticides. Various contributors to yield, such as physiology, biochemistry and gene expression have been implemented as screening tools for tolerance to high temperatures under growth cabinet and laboratory conditions but there has been little extension of these mechanisms to field based systems. This study evaluates tools for the identification of specific genotypic thermotolerance under field conditions using a multi-level ‘top down’ approach from crop to gene level. Field experiments were conducted in seasons 1 (2006) and 3 (2007) at Narrabri (Australia) and season 2 (2006) in Texas (The United States of America) and were supplemented by growth cabinet experiments to quantify cultivar differences in yield, physiology, biochemical function and gene expression under high temperatures. Whole plants were subjected to high temperatures in the field through the construction of Solarweave® tents and in the growth cabinet at a temperature of 42 oC. The effectiveness of these methods was then evaluated to establish a rapid and reliable screening tool for genotype specific thermotolerance that could potentially improve the efficiency of breeding programs and aid the development to high yielding cultivars for hot growing regions. Cotton cultivars Sicot 53 and Sicala 45 were evaluated for thermotolerance using crop level measurements (yield and fibre quality) and whole plant measurements (fruit retention) to determine the efficacy of these measurements as screening tools for thermotolerance under field conditions. Sicot 53 was selected as a relatively thermotolerant cultivar whereas Sicala 45 was selected as a cultivar with a lower relative thermotolerance and this assumption was made on the basis of yield in hot and cool environments under the CSIRO Australian cotton breeding program. Yield and fruit retention were lower under tents compared with ambient conditions in all 3 seasons. Yield and fruit retention were highly correlated in season 1 and were higher for Sicot 53 compared to Sicala 45 suggesting that fruit retention is a primary limitation to yield in a hot season. Thus yield and fruit retention are good indicators of thermotolerance in a hot season. Temperature treatment and cultivar differences were determined for fibre quality in seasons 1 and 3; however, quality exceeded the industry minimum thereby indicating that fibre quality is not a good determinant of thermotolerance. Physiological determinants of plant functionality such as photosynthesis, electron transport rate, stomatal conductance and transpiration rate were determined for cultivars Sicot 53 and Sicala 45 under the tents and an index of these parameters was also analysed to determine overall plant physiological capacity in the field. Physiological capacity was also determined under high temperatures in the growth cabinet using a light response curve at various levels of photosynthetically active radiation (PAR). Photosynthesis and electron transport rate decreased, whilst stomatal conductance and transpiration rate increased under the tents as well as under high temperatures in the growth cabinet. Photosynthesis and electron transport rate were higher for Sicot 53 but stomatal conductance and transpiration rate were higher for Sicala 45 under the tents. No cultivar differentiation was evident for plants grown under high temperatures in the growth cabinet. Temperature treatment and cultivar differences in physiological function were greater in a hot year (season 1), thereby indicating the importance of cultivar selection for thermotolerance in the presence of stress. Electron transport rate was correlated with yield in season 1, thus suggesting the suitability of this method for broad genotypic screening for thermotolerance under field conditions. Biochemical processes such as membrane integrity and enzyme viability were used to determine cultivar specific thermotolerance under high temperature stress in the laboratory, field and growth cabinet. Electrolyte leakage is an indicator of decreased membrane integrity and may be estimated by the relative electrical conductivity or relative cellular injury assays. The heat sensitivity of dehydrogenase activity, a proxy for cytochrome functionality and capacity for mitochondrial electron transport, may be quantified spectrophotometrically. Cellular membrane integrity and enzyme viability decreased sigmoidally with exposure to increasing temperatures in a water bath. Membrane integrity was higher for Sicot 53 compared with Sicala 45 under the tents and under high temperatures in the growth cabinet. No temperature treatment or cultivar differences were found for enzyme viability under the tents; however, enzyme viability for Sicala 45 was higher in the growth cabinet compared with Sicot 53. Relative electrical conductivity was strongly correlated with yield under ambient field conditions and under the tents, suggesting impairment of electron flow through photosynthetic and/or respiratory pathways, thus contributing to lower potential for ATP production and energy generation for yield contribution. Thus, the membrane integrity assay was considered to be a rapid and reliable tool for thermotolerance screening in cotton cultivars. Gene expression was examined for cultivars Sicot 53 and Sicala 45 grown under high (42 oC) temperatures in the growth cabinet. Rubisco activase expression was quantified using quantitative real-time polymerase chain reaction analysis and was decreased under high temperatures and was lower for Sicala 45 than Sicot 53. Maximum cultivar differentiation was found after 1.0 h exposure to high temperatures and hence, leaf tissue sampled from this time point was further analysed for global gene profiling using cDNA microarrays. Genes involved in metabolism, heat shock protein generation, electron flow and ATP generation were down-regulated under high temperatures in the growth cabinet and a greater number of genes were differentially expressed for Sicala 45, thereby indicating a higher level of heat stress and a greater requirement for mobilisation of protective and compensatory mechanisms compared with Sicot 53. Cultivar specific thermotolerance determination using gene profiling may be a useful tool for understanding the underlying basis of physiological and biochemical responses to high temperature stress in the growth cabinet. There is future opportunity for profiling genes associated with heat stress and heat tolerance for identification of key genes associated with superior cultivar performance under high temperature stress and characterisation of these genes under field conditions. This research has identified cultivar differences in yield under field conditions and has identified multiple physiological and biochemical pathways that may contribute to these differences. Future characterisation of genes associated with heat stress and heat tolerance under growth cabinet conditions may be extended to field conditions, thus providing the underlying basis of the response of cotton to high temperature stress. Electron transport rate and relative electrical conductivity were found to be rapid and reliable determinants of cultivar specific thermotolerance and hence may be extended to broad-spectrum screening of a range of cotton cultivars and species and under a range of abiotic stress. This will enable the identification of superior cotton cultivars for incorporation into local breeding programs for Australian and American cotton production systems.
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Thermotolerance of cottonCottee, Nicola Sandra January 2009 (has links)
Doctor of Philosophy (PhD) / The Australian cotton industry has developed high yielding and high quality fibre production systems and attributes a significant contribution of this achievement to highly innovative breeding programs, specifically focused on the production of premium quality lint for the export market. Breeding programs have recently shifted attention to the development of new germplasm with superior stress tolerance to minimise yield losses attributed to adverse environmental conditions and inputs such as irrigation, fertilisers and pesticides. Various contributors to yield, such as physiology, biochemistry and gene expression have been implemented as screening tools for tolerance to high temperatures under growth cabinet and laboratory conditions but there has been little extension of these mechanisms to field based systems. This study evaluates tools for the identification of specific genotypic thermotolerance under field conditions using a multi-level ‘top down’ approach from crop to gene level. Field experiments were conducted in seasons 1 (2006) and 3 (2007) at Narrabri (Australia) and season 2 (2006) in Texas (The United States of America) and were supplemented by growth cabinet experiments to quantify cultivar differences in yield, physiology, biochemical function and gene expression under high temperatures. Whole plants were subjected to high temperatures in the field through the construction of Solarweave® tents and in the growth cabinet at a temperature of 42 oC. The effectiveness of these methods was then evaluated to establish a rapid and reliable screening tool for genotype specific thermotolerance that could potentially improve the efficiency of breeding programs and aid the development to high yielding cultivars for hot growing regions. Cotton cultivars Sicot 53 and Sicala 45 were evaluated for thermotolerance using crop level measurements (yield and fibre quality) and whole plant measurements (fruit retention) to determine the efficacy of these measurements as screening tools for thermotolerance under field conditions. Sicot 53 was selected as a relatively thermotolerant cultivar whereas Sicala 45 was selected as a cultivar with a lower relative thermotolerance and this assumption was made on the basis of yield in hot and cool environments under the CSIRO Australian cotton breeding program. Yield and fruit retention were lower under tents compared with ambient conditions in all 3 seasons. Yield and fruit retention were highly correlated in season 1 and were higher for Sicot 53 compared to Sicala 45 suggesting that fruit retention is a primary limitation to yield in a hot season. Thus yield and fruit retention are good indicators of thermotolerance in a hot season. Temperature treatment and cultivar differences were determined for fibre quality in seasons 1 and 3; however, quality exceeded the industry minimum thereby indicating that fibre quality is not a good determinant of thermotolerance. Physiological determinants of plant functionality such as photosynthesis, electron transport rate, stomatal conductance and transpiration rate were determined for cultivars Sicot 53 and Sicala 45 under the tents and an index of these parameters was also analysed to determine overall plant physiological capacity in the field. Physiological capacity was also determined under high temperatures in the growth cabinet using a light response curve at various levels of photosynthetically active radiation (PAR). Photosynthesis and electron transport rate decreased, whilst stomatal conductance and transpiration rate increased under the tents as well as under high temperatures in the growth cabinet. Photosynthesis and electron transport rate were higher for Sicot 53 but stomatal conductance and transpiration rate were higher for Sicala 45 under the tents. No cultivar differentiation was evident for plants grown under high temperatures in the growth cabinet. Temperature treatment and cultivar differences in physiological function were greater in a hot year (season 1), thereby indicating the importance of cultivar selection for thermotolerance in the presence of stress. Electron transport rate was correlated with yield in season 1, thus suggesting the suitability of this method for broad genotypic screening for thermotolerance under field conditions. Biochemical processes such as membrane integrity and enzyme viability were used to determine cultivar specific thermotolerance under high temperature stress in the laboratory, field and growth cabinet. Electrolyte leakage is an indicator of decreased membrane integrity and may be estimated by the relative electrical conductivity or relative cellular injury assays. The heat sensitivity of dehydrogenase activity, a proxy for cytochrome functionality and capacity for mitochondrial electron transport, may be quantified spectrophotometrically. Cellular membrane integrity and enzyme viability decreased sigmoidally with exposure to increasing temperatures in a water bath. Membrane integrity was higher for Sicot 53 compared with Sicala 45 under the tents and under high temperatures in the growth cabinet. No temperature treatment or cultivar differences were found for enzyme viability under the tents; however, enzyme viability for Sicala 45 was higher in the growth cabinet compared with Sicot 53. Relative electrical conductivity was strongly correlated with yield under ambient field conditions and under the tents, suggesting impairment of electron flow through photosynthetic and/or respiratory pathways, thus contributing to lower potential for ATP production and energy generation for yield contribution. Thus, the membrane integrity assay was considered to be a rapid and reliable tool for thermotolerance screening in cotton cultivars. Gene expression was examined for cultivars Sicot 53 and Sicala 45 grown under high (42 oC) temperatures in the growth cabinet. Rubisco activase expression was quantified using quantitative real-time polymerase chain reaction analysis and was decreased under high temperatures and was lower for Sicala 45 than Sicot 53. Maximum cultivar differentiation was found after 1.0 h exposure to high temperatures and hence, leaf tissue sampled from this time point was further analysed for global gene profiling using cDNA microarrays. Genes involved in metabolism, heat shock protein generation, electron flow and ATP generation were down-regulated under high temperatures in the growth cabinet and a greater number of genes were differentially expressed for Sicala 45, thereby indicating a higher level of heat stress and a greater requirement for mobilisation of protective and compensatory mechanisms compared with Sicot 53. Cultivar specific thermotolerance determination using gene profiling may be a useful tool for understanding the underlying basis of physiological and biochemical responses to high temperature stress in the growth cabinet. There is future opportunity for profiling genes associated with heat stress and heat tolerance for identification of key genes associated with superior cultivar performance under high temperature stress and characterisation of these genes under field conditions. This research has identified cultivar differences in yield under field conditions and has identified multiple physiological and biochemical pathways that may contribute to these differences. Future characterisation of genes associated with heat stress and heat tolerance under growth cabinet conditions may be extended to field conditions, thus providing the underlying basis of the response of cotton to high temperature stress. Electron transport rate and relative electrical conductivity were found to be rapid and reliable determinants of cultivar specific thermotolerance and hence may be extended to broad-spectrum screening of a range of cotton cultivars and species and under a range of abiotic stress. This will enable the identification of superior cotton cultivars for incorporation into local breeding programs for Australian and American cotton production systems.
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Caractérisation des propriétés antibactériennes de textiles fonctionnalisés avec de l’argent ou du PolyHexaMéthylène Biguanide (PHMB) / Antibacterial properties characterization of functionalized textiles with silver or PolyHexaMethylene Biguanide (PHMB)Chadeau, Élise 15 February 2011 (has links)
Dans l’industrie agro-alimentaire, l’adhésion de micro-organismes altérants ou pathogènes sur les surfaces induit des effets néfastes à la fois en termes de qualité, d’hygiène et de santé publique. Les vêtements professionnels constituent un des vecteurs de contamination par le personnel. Ce travail de thèse concerne l’évaluation de l’activité antimicrobienne de textiles antimicrobiens développés pour le secteur hospitalier et le secteur agro-alimentaire et rentre dans le cadre du projet collaboratif Actiprotex. Trois méthodologies ont été employées pour le dépôt d’agents antimicrobiens sur les textiles : méthodologie plasma (PVD/PECVD) ou sol-gel pour le dépôt d’argent, foulardage avec une solution contenant du laurylsulfate et du Poly Hexaméthylène Biguanide (PHMB) pour provoquer une co-précipitation du PHMB. Les activités antimicrobiennes de chaque textile ont été évaluées après 24 h de contact (suivant la norme ISO 20743-2005). Les quantités d’agent antimicrobien à la surface des textiles ont été évaluées par 2 techniques d’analyses de surface : la spectroscopie photoélectronique par rayons X (XPS) et la spectrométrie de masse d’ions secondaires (ToF-SIMS). Les textiles traités par plasma à l’argent se sont avérés être efficaces vis-à-vis de Listeria innocua LRGIA 01. Pour le traitement sol-gel, les textiles testés étaient également très actifs vis-à-vis de L. innocua LRGIA 01 et d’Escherichia coli XL1 blue. Cependant, E. coli XL1 blue est apparue plus sensible à l’argent que L. innocua LRGIA 01. Les textiles traités au PHMB se sont également avérés être très actifs vis-à-vis de L. innocua LRGIA 01 et de Staphylococcus aureus méthi-R nosoco 3011 cependant des cellules viables mais non cultivables (VNC) ont également été mises en évidence après contact de ces 2 souches avec le textile traité au PHMB. Pseudomonas aeruginosa ATCC 15742 s’est quant à elle avérée être plus résistante que ces 2 souches. La tenue aux lavages industriels ou ménagers des dépôts plasma d’argent et de PHMB par foulardage a également été évaluée. Les dépôts plasma d’argent résistent mal au lavage alors que le dépôt PHMB par foulardage s’est avéré résister à 10 lavages industriels. Pour mieux comprendre le mécanisme d’action du PHMB vis-à-vis de L. innocua LRGIA 01 en milieu liquide, trois approches ont été mises en oeuvre : la microscopie à épifluorescence en présence de marqueurs fluorescents pour évaluer l’état de la membrane des cellules, la spectrofluorimétrie en présence de sondes fluorescentes (DPH et TMA-DPH) pour évaluer la fluidité de la membrane des cellules et enfin la spectroscopie infrarouge à transformée de Fourier (IRTF) pour évaluer les changements de conformation de la membrane. Les résultats obtenus par ces 3 méthodes permettent de proposer un mode d’action du PHMB de type « carpet », c’est à dire une fixation de l’agent antimicrobien en surface puis une désorganisation de la membrane conduisant à des changements de sa conformation puis à la formation de pores et à la mort cellulaire / Adhesion of pathogenic or spoilage microorganisms on the surfaces present in food industry can lead to contaminations of foods. Besides the economical impact for this industrial sector, these contaminations might alleviate food quality and hygiene and affect public health. Professional clothes constitute one of the vectors of contamination by the staff of food-processing industry. This work is a part of a collaborative project (Actiprotex) and concerns the evaluation of the antimicrobial activity of antimicrobial textiles developed for the hospital sector and the food-processing industry. Three methodologies were employed to obtain deposits of antimicrobial agents on textiles surfaces: plasma (PVD / PECVD) or sol-gel methodologies for the silver deposit and spin coating with a solution containing laurylsulfate and PolyHexamethylene Biguanide (PHMB). The antimicrobial activities of functionalized textiles were estimated after 24 hours of contact (according to the standard ISO 20743- 2005). The quantities of antimicrobial agent at the extreme surface of the textiles were estimated by two techniques of analyses of surface: the photoelectronic spectroscopy by X-rays (XPS) and the mass spectrometry of secondary ions (ToF-SIMS). Textiles functionalized by plasma methodology with silver were effective against Listeria innocua LRGIA 01. For the textiles functionalized by sol-gel methodology, the tested textiles were also very active towards L. innocua LRGIA 01 and Escherichia coli XL1 blue. However, E. coli XL1 blue seemed to be more sensitive to the silver on textiles than the L. innocua LRGIA 01 strain. Textiles treated with the PHMB also turned out to be very active towards L. innocua LRGIA 01 and Staphylococcus aureus methi-R nosoco 3011, however viable but not cultivable cell (VNC) were also revealed after contact of these 2 strains with the PHMB treated textile. Pseudomonas aeruginosa ATCC 15742 was more resistant to PHMB than these 2 strains. The washing resistance of silver- or PHMB-deposits was also estimated. Most of the silver deposit following plasma treatment was washed out while the PHMB deposit turned out to resist to 10 industrial washes. To understand the mechanism of action of the PHMB against L. innocua LRGIA 01, three approaches were considered: the epifluorescence microscopy in the presence of fluorescent dyes to estimate the state of the membrane cells, spectrofluorimetry in the presence of fluorescent probes (DPH and TMA-DPH) to estimate the membrane fluidity of cells and finally the infrared transformed Fourier spectroscopy (IRTF) to estimate the changes of conformation of the membrane
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Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic ProductsMcCanna, David January 2009 (has links)
The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes.
The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.
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Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic ProductsMcCanna, David January 2009 (has links)
The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes.
The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.
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