http://hdl.handle.net/10023/661 2013-04-28T00:27:05Z http://hdl.handle.net/10023/3218 Abstract: The mitochondria are a vibrant hub for many problems that occur in Alzheimer’s disease. The enzyme amyloid-ß binding alcohol dehydrogenase (ABAD) and Cyclophilin D (CypD) are two key mitochondrial proteins that have essential functions in Alzheimer’s disease. ABAD is crucial in the generation of energy via the ß-oxidation of fatty acids, and CypD has been linked to Alzheimer’s disease through the initiation of necrosis. Changes in glucose metabolism have been observed in the brains of Alzheimer’s disease sufferers. This suggests that neurons require an alternative energy source that can bypass glycolysis in order to produce energy. The oxidation of fatty acids is crucial at this point as the products of this catabolism can feed into the second stage of the respiratory cycle. In Alzheimer’s disease, Amyloid-ß (Aß) has been found to bind to ABAD distorting the catalytic site changing its activity. The first objective of this thesis was to investigate a potential previously reported interaction between ABAD and CypD. To explore this further, FRET analysis and immunoprecipitation studies were conducted. Though no strong interactions were observed from the immunoprecipitation studies, live cell FRET analysis did reveal a small/weak interaction between CypD and ABAD. Additional studies also showed a decrease in ABAD activity in the presence of CypD, suggesting that there could be functional consequences from this interaction between CypD and ABAD.I also explored the effect of changing cellular energy sources on the activity of ABAD. ABAD activity was found to increase under conditions of reduced glucose in both HEK 293 and SK-N-SH cells expressing ABAD. In addition, Alois Alzheimer initially reported changes in lipids. These reported changes in lipids were explored under conditions where there was increased expression of ABAD and in the presence of Aß. On the whole, the changes suggested that there was a shift in the metabolism of fatty acids when ABAD was expressed further implying a change in energy sources in the Alzheimer’s disease brain. 2012-11-30T00:00:00Z Allen, Zoe Eleanor The mitochondria are a vibrant hub for many problems that occur in Alzheimer’s disease. The enzyme amyloid-ß binding alcohol dehydrogenase (ABAD) and Cyclophilin D (CypD) are two key mitochondrial proteins that have essential functions in Alzheimer’s disease. ABAD is crucial in the generation of energy via the ß-oxidation of fatty acids, and CypD has been linked to Alzheimer’s disease through the initiation of necrosis. Changes in glucose metabolism have been observed in the brains of Alzheimer’s disease sufferers. This suggests that neurons require an alternative energy source that can bypass glycolysis in order to produce energy. The oxidation of fatty acids is crucial at this point as the products of this catabolism can feed into the second stage of the respiratory cycle. In Alzheimer’s disease, Amyloid-ß (Aß) has been found to bind to ABAD distorting the catalytic site changing its activity. The first objective of this thesis was to investigate a potential previously reported interaction between ABAD and CypD. To explore this further, FRET analysis and immunoprecipitation studies were conducted. Though no strong interactions were observed from the immunoprecipitation studies, live cell FRET analysis did reveal a small/weak interaction between CypD and ABAD. Additional studies also showed a decrease in ABAD activity in the presence of CypD, suggesting that there could be functional consequences from this interaction between CypD and ABAD.I also explored the effect of changing cellular energy sources on the activity of ABAD. ABAD activity was found to increase under conditions of reduced glucose in both HEK 293 and SK-N-SH cells expressing ABAD. In addition, Alois Alzheimer initially reported changes in lipids. These reported changes in lipids were explored under conditions where there was increased expression of ABAD and in the presence of Aß. On the whole, the changes suggested that there was a shift in the metabolism of fatty acids when ABAD was expressed further implying a change in energy sources in the Alzheimer’s disease brain. http://hdl.handle.net/10023/3214 Abstract: Although ants have numerous, often beneficial interactions with plants, as pollinators they are poor. Potential reasons for this include restrictions resulting from their morphology and specific foraging behaviours, and detrimental effects of their surface secretions on pollen. This, coupled with other possible negative effects of ants on floral structures, puts pressure on plants to exclude ants from flowers. One common strategy to achieve this is via behaviour- modifying repellent floral volatiles; however, few studies have identified the volatiles concerned. Here I considered two aspects of this interaction. Firstly, I assessed seven temperate angiosperm species for floral repellence to Formica aquilonia ants using a simple two-way olfactometer. In agreement with previous studies showing that floral ant-repellence is common, significant repellent effects were found in 3/7 species. I also analysed the floral bouquet of Petasites fragrans, a plant previously shown to possess ant-repellent floral volatiles. The most prominent volatile was identified as 4- methoxybenzaldehyde and olfactometer testing of a pure sample of this confirmed it as the likely source of floral repellence in P. fragrans. Although the natural interactions between P. fragrans and ants are unknown, intriguingly 4-methoxybenzaldehyde has been detected from floral volatiles of two further species with frequent ant interactions. A second study compared effects of ants and bees on pollen function to explore the supposed significance of ant-induced reductions in pollen viability. Lily pollen was exposed to either F. aquilonia, Apis mellifera, or Bombus pascuorum, germinated in vitro and assessed for viability. Small, marginally significant reductions in viability were identified for all three insects compared to a control, but with no differences in the reduction between each insect. Although this indicates that the pollen inviability hypothesis for the scarcity of ant pollination may be incorrect, a comparative study with several pollinator and plant species is needed to substantiate this conclusion. 2012-06-19T00:00:00Z Pattrick, Johnathan G. Although ants have numerous, often beneficial interactions with plants, as pollinators they are poor. Potential reasons for this include restrictions resulting from their morphology and specific foraging behaviours, and detrimental effects of their surface secretions on pollen. This, coupled with other possible negative effects of ants on floral structures, puts pressure on plants to exclude ants from flowers. One common strategy to achieve this is via behaviour- modifying repellent floral volatiles; however, few studies have identified the volatiles concerned. Here I considered two aspects of this interaction. Firstly, I assessed seven temperate angiosperm species for floral repellence to Formica aquilonia ants using a simple two-way olfactometer. In agreement with previous studies showing that floral ant-repellence is common, significant repellent effects were found in 3/7 species. I also analysed the floral bouquet of Petasites fragrans, a plant previously shown to possess ant-repellent floral volatiles. The most prominent volatile was identified as 4- methoxybenzaldehyde and olfactometer testing of a pure sample of this confirmed it as the likely source of floral repellence in P. fragrans. Although the natural interactions between P. fragrans and ants are unknown, intriguingly 4-methoxybenzaldehyde has been detected from floral volatiles of two further species with frequent ant interactions. A second study compared effects of ants and bees on pollen function to explore the supposed significance of ant-induced reductions in pollen viability. Lily pollen was exposed to either F. aquilonia, Apis mellifera, or Bombus pascuorum, germinated in vitro and assessed for viability. Small, marginally significant reductions in viability were identified for all three insects compared to a control, but with no differences in the reduction between each insect. Although this indicates that the pollen inviability hypothesis for the scarcity of ant pollination may be incorrect, a comparative study with several pollinator and plant species is needed to substantiate this conclusion. http://hdl.handle.net/10023/669 Abstract: Density estimates for six large herbivore species were obtained through analysis of line transect data from Nagarhole National Park, south-western India, collected between 1989 and 2000. These species were Chital (Axis axis), Sambar (Cervus unicolor), Gaur (Bos gaurus), Wild Pig (Sus scrofa), Muntjac (Muntiacus muntjak) and Asian Elephant (Elephas maximus). Multiple Covariate Distance Sampling (MCDS) models were used to derive these density estimates. The distance histograms showed a relatively large spike at zero, which can lead to problems when fitting MCDS models. The effects of this spike were investigated and remedied by forward truncation. Density estimates from unmodified dataset were 10-15% higher than estimates from the forward truncated data, with this going up to 37% for Muntjac. These could possibly be over estimates. Empirical trend models were then fit to the density estimates. Overall trends were stable, though there were intra-habitat differences in trends for some species. The trends were similar both in cases where forward truncation was done as well as in those where they were not. Description: MRes in Environmental Biology 2005-01-01T00:00:00Z Gangadharan, Aditya Density estimates for six large herbivore species were obtained through analysis of line transect data from Nagarhole National Park, south-western India, collected between 1989 and 2000. These species were Chital (Axis axis), Sambar (Cervus unicolor), Gaur (Bos gaurus), Wild Pig (Sus scrofa), Muntjac (Muntiacus muntjak) and Asian Elephant (Elephas maximus). Multiple Covariate Distance Sampling (MCDS) models were used to derive these density estimates. The distance histograms showed a relatively large spike at zero, which can lead to problems when fitting MCDS models. The effects of this spike were investigated and remedied by forward truncation. Density estimates from unmodified dataset were 10-15% higher than estimates from the forward truncated data, with this going up to 37% for Muntjac. These could possibly be over estimates. Empirical trend models were then fit to the density estimates. Overall trends were stable, though there were intra-habitat differences in trends for some species. The trends were similar both in cases where forward truncation was done as well as in those where they were not. http://hdl.handle.net/10023/667 Abstract: Management schemes dedicated to the conservation of wildlife populations rely on the effective monitoring of population size, and this requires the accurate and precise estimation of abundance. The accuracy and precision of estimates are determined to a large extent by the survey design. Line transect surveys are commonly applied to wildlife population assessments in which the primary purpose of a survey design is to ensure that the critical distance sampling assumptions are met. Little information is available regarding cetacean abundance in the Archipelago of the Azores (Portugal). This study aims to design a line transect shipboard survey that allows the collection of data required to provide abundance estimates for such species. Several aspects must be taken into consideration when designing a survey to estimate cetacean abundance. This is an iterative process, and there is a constant trade off between the logistic constraints and the desired statistical robustness. Information on this process is provided to aid policy makers and environmental managers, such as the criteria used for the choices made when defining the elements of a survey design. Three survey effort scenarios are provided to illustrate the range of possibilities between statistical robustness and logistic/ management restrictions. A survey is designed for the more economical scenario (L=5000Km), although the second scenario is the one recommended to be implemented (L=17,600Km) given it provides robust estimates of abundance (CV<=0.2). Description: Revised version November 2008. MRes in Marine Mammal Science 2008-01-01T00:00:00Z Faustino, Cláudia Estevinho Santos Management schemes dedicated to the conservation of wildlife populations rely on the effective monitoring of population size, and this requires the accurate and precise estimation of abundance. The accuracy and precision of estimates are determined to a large extent by the survey design. Line transect surveys are commonly applied to wildlife population assessments in which the primary purpose of a survey design is to ensure that the critical distance sampling assumptions are met. Little information is available regarding cetacean abundance in the Archipelago of the Azores (Portugal). This study aims to design a line transect shipboard survey that allows the collection of data required to provide abundance estimates for such species. Several aspects must be taken into consideration when designing a survey to estimate cetacean abundance. This is an iterative process, and there is a constant trade off between the logistic constraints and the desired statistical robustness. Information on this process is provided to aid policy makers and environmental managers, such as the criteria used for the choices made when defining the elements of a survey design. Three survey effort scenarios are provided to illustrate the range of possibilities between statistical robustness and logistic/ management restrictions. A survey is designed for the more economical scenario (L=5000Km), although the second scenario is the one recommended to be implemented (L=17,600Km) given it provides robust estimates of abundance (CV<=0.2). http://hdl.handle.net/10023/665 Abstract: The development of an animal-borne instrument that can record oceanographic measurements (CTD-SRDL) has enabled the collection of oceanographic data at a scale relevant to the counterpart behavioural data, both in time and 3-dimensional space. This has advanced the potential for studies of the behaviour of deep-diving marine animals and the way in which they respond to their environment, yet the nature of the data delivered by CTD-SRDLs presents substantial analytical challenges and places constraints on its biological interpretation. Behavioural and environmental data, collected using CTD-SRDLs deployed on southern elephant seals (Mirounga leonina) from the South Georgia subpopulation in 2004 and 2005, are analysed for 13 females and 4 males (21,015 dives). Compressed dive profiles are used to classify individual dives into six distinct types based on their 2-dimensional time-depth characteristics using random forest classification. The relationship between dive type and environmental variables, derived from oceanographic data recorded on board the animals, is investigated in the context of regression analysis, employing a multinomial model, as well as independently fitted Generalized Linear Models (GLM) and Generalized Additive Models (GAM) for each dive type. Regression is not found to be an appropriate method for analysing abstracted behavioural dive data, and other methods are suggested. We show that functional specializations can be manifested within a dive type, using square bottom dives (SQ) as an example. The usefulness of dive classification is discussed in the context of behavioural interpretation, and validity of the ecological functions attached to each class. Preliminary analyses are important drivers of further research into improving the interpretability of abstracted behavioural data, and developing efficient, standardized methods for widespread application to this type of data, which is obtained in abundance via satellite telemetry. Description: BL 5019 Research project. MRes Environmental Biology 2007-01-01T00:00:00Z Photopoulos, Theoni The development of an animal-borne instrument that can record oceanographic measurements (CTD-SRDL) has enabled the collection of oceanographic data at a scale relevant to the counterpart behavioural data, both in time and 3-dimensional space. This has advanced the potential for studies of the behaviour of deep-diving marine animals and the way in which they respond to their environment, yet the nature of the data delivered by CTD-SRDLs presents substantial analytical challenges and places constraints on its biological interpretation. Behavioural and environmental data, collected using CTD-SRDLs deployed on southern elephant seals (Mirounga leonina) from the South Georgia subpopulation in 2004 and 2005, are analysed for 13 females and 4 males (21,015 dives). Compressed dive profiles are used to classify individual dives into six distinct types based on their 2-dimensional time-depth characteristics using random forest classification. The relationship between dive type and environmental variables, derived from oceanographic data recorded on board the animals, is investigated in the context of regression analysis, employing a multinomial model, as well as independently fitted Generalized Linear Models (GLM) and Generalized Additive Models (GAM) for each dive type. Regression is not found to be an appropriate method for analysing abstracted behavioural dive data, and other methods are suggested. We show that functional specializations can be manifested within a dive type, using square bottom dives (SQ) as an example. The usefulness of dive classification is discussed in the context of behavioural interpretation, and validity of the ecological functions attached to each class. Preliminary analyses are important drivers of further research into improving the interpretability of abstracted behavioural data, and developing efficient, standardized methods for widespread application to this type of data, which is obtained in abundance via satellite telemetry.