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Subject: search.filters.subject.Stress (Physiology)

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    The minimal anaesthesia model : development and refinement of the concept and subsequent practical applications : a collection of papers and a monograph presented in application for the degree of Doctor of Science at Massey University, Manawatu
    (Massey University, 2020) Johnson, Craig
    The research presented in this thesis represents both my development of the minimal anaesthesia model and its application in a number of theoretical and applied areas of animal welfare science. The use of this methodology, especially when combined with other techniques such as behavioural analysis, has proven to be a very powerful way to investigate the perception of noxious stimuli. In particular it enables clear links between physical responses and the underlying affective state of the animal to be made. These links have both expanded our understanding of the development and mechanisms of pain perception in the central nervous system of mammals and also enabled the extent to which animal husbandry procedures such as castration, tail docking and killing are painful to be measured. These latter applied studies have been used as the basis for significant changes to the ways in which painful procedures are carried out. They have contributed to new ways of providing pain relief in a variety of contexts and to changing legislation to ensure that pain relief is used in practice.
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    Requirements of Escherichia coli to survive stress induced by the secretin, pIV : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University, Manawatū, New Zealand
    (Massey University, 2018) Bagley, Stefanie Jayne
    Pathogenic Gram-negative bacteria utilise complex multiprotein and functionally unrelated trans-envelope machineries to secrete toxins and other virulence factors. Such machineries are referred to as secretion systems. These contain large, membrane-inserted homologous channels called a secretin. These secretion systems include the type II and III secretion systems (T2SS and T3SS), type IV pili assembly system (T4PS), and the filamentous phage assembly-secretion system (FFSS). Secretins are homomultimers with radial symmetry blocked by an inner gate or septum and have a pore size of up to 10 nm. As determined by previous studies on the FFSS secretin, pIV, and the T3SS secretin, InvG, there is a cost associated with the insertion of large membrane channels. Membrane integrity is disrupted, leaving the bacterial cell highly susceptible to antibiotics and environmental stressors. As a result, Gram-negative bacteria have developed stress response pathways which upregulate genes to mitigate this secretin induced stress. These are the Phage Shock Protein response (Psp), Conjugative plasmid expression (Cpx), Regulation of capsular synthesis (Rcs), and SoxRS Superoxide response (Sox). Not all individual genes within these stress response pathways are necessarily required for the survival of Escherichia coli expressing secretin. Stress can be induced in E. coli by expression of leaky pIV mutants as they are open, not gated, under physiological conditions and imitate the actively secreting channel. A synthetic lethality assay was performed to determine the importance of the key regulators from four stress response pathways (PspF, CpxR, RcsA, RcsB, SoxR, and SoxS) on cell viability in the presence of the leaky secretin mutant, pIV-E292K. Here it was determined that the Psp, Rcs and, (to a lesser extent), Cpx regulons, confer a protective effect on E. coli K-12 experiencing stress induced by pIV-E292K. Expression of pIV-E292K mutant also induced an Rcs-dependent capsular polysaccharide phenotype indicating upregulation of Rcs in response to leaky pIV production. These three responses are potential drug targets in the fight against antibiotic-resistant infections. Inhibition of the stress response may prevent mitigation of membrane stress, thereby killing the channel-expressing bacteria.
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    Corticosterone responses to captivity and sampling stress in mallard (Anas platyrhynchos) and grey duck (Anas superciliosa) : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Physiology at Massey University
    (Massey University, 1994) Forman, Mark
    1. The aim of this study was to investigate the influence of capture and captivity stress on plasma corticosterone levels and breeding success in mallard and grey ducks. Measurements of plasma corticosterone levels were used to identify factors that cause stress and to identify individual birds with low stress responses and a greater likelihood of a successful breeding in captivity than their peers. The effect on corticosterone levels of the stress associated with the collection of blood samples was investigated and different sampling regimes for measuring corticosterone responses to stress were examined. The use of exogenous glucose administration and the placing of ducks into darkened boxes to lower corticosterone levels was also studied. 2. Corticosterone levels in wild mallards after capture were higher than levels in ducks held captive for 3 or 5 months. Corticosterone levels decreased in captive ducks in relation to the time spent in captivity and amount of contact spent with people. 3. Corticosterone levels repeatedly measured over 8 months varied between individual captive grey duck. The only 2 female ducks to rear ducklings, and their mates, all had lower corticosterone levels before the breeding season than the remaining 4 female and 3 male ducks. 4. The variation in corticosterone levels and responses between individual grey duck and the negative relationship between corticosterone levels and body weight may have been due, in part, to the existence of a dominance hierarchy amongst the grey ducks. 5. Corticosterone levels in winter may indicate potential breeding success and, can be used to identify stressful factors in the captive environment. 6. The observation of an increase in corticosterone levels with the sampling and handling of ducks depends on the magnitude of levels in the first sample obtained and on the frequency with which samples are obtained thereafter. 7. High corticosterone levels will decrease if a duck is placed in a darkened individual box or given an oral dose of 10 ml of 0.84M or 1.38M glucose. 8. It is concluded that the measurement of corticosterone levels can be used to indicate factors that may affect the breeding performance of birds. Methods for minimising the stress associated with the capture and captivity of wild birds can also be identified from the measurement of corticosterone levels.
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    Corticosterone responses to different stimuli and phenotypic plasticity in corticosterone responses in the kororā (little penguin, Eudyptula minor) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University, Manawatu, New Zealand
    (Massey University, 2018) Choi, MinSeo
    The overall aims of the research presented in this thesis were to compare in little penguins (Eudyptula minor) corticosterone concentrations following exposure to a variety of stimuli with corticosterone responses to handling, to investigate the relationship between corticosterone response to handling and corticosterone concentrations after exposure to different stimuli, and to examine plasticity in corticosterone responses. The study involved measurement of corticosterone concentrations in blood samples collected after a 15 min stimulus. Handling resulted in a greater mean plasma corticosterone concentration than all other stimuli. Plasma corticosterone concentrations in little penguins in nestboxes after the presentation of a novel object were greater than concentrations after the sound of dog barking and the sound of human talking. Corticosterone concentrations were higher in birds that were exposed to penguin alarm calls than birds exposed to human talking. Differences between mean corticosterone concentrations after human talking and dog barking, and between mean concentrations after the penguin alarm call and the novel object, were not significant. The mean concentration after human talking was the lowest and the mean concentration after novel object was the highest relative to responses to handling. Corticosterone concentrations after handling and concentrations after exposure to other stimuli were not correlated. A reaction norm revealed the existence of plasticity in corticosterone concentrations in little penguins. The reaction norm approach used to determine plasticity in this study did not allow for the quantification of the degree of plasticity. The findings of the present study have provided information about the way little penguins respond to different type of stimuli, whether responses to handling are similar to responses to other stimuli in the same bird, and show that the use of a reaction norm approach can provide useful information about plasticity in corticosterone responses to different stimuli in birds.
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    The development of the corticosterone stress response of kororā (little penguin, Eudyptula minor) chicks in response to frequent handling : a thesis presented in partial fulfilment of the requirements of the degree of Master of Science in Physiology at Massey University
    (Massey University, 2018) Ogle, Shelley
    In birds, when a stressor is encountered, the hypothalamo-pitiutary-adrenal (HPA) axis is activated to produce the corticosteroid, corticosterone. The production of this hormone incites a flight or fight response in order to best avoid long-term damage from the stressor. However, prolonged or repeated exposure to high levels of corticosterone can have damaging behavioural and physiological effects. For this reason, high levels of the hormone should be avoided where possible in developing chicks. Chicks of altricial species in particular, seldom hatch with a highly functioning HPA axis so as to avoid these detrimental effects while their parents are still protecting them from major stressors such as predators, adverse weather and low food availability. Previously, studies have mapped the development of the HPA axis in a range of species or studied the effects of stress from a young age on future behavioural or physiological responses. This current study aimed to not only describe any adverse effects observed as a result of increased encounters with stressors but also track the development of the HPA axis in kororā (little penguin, Eudyptula minor) chicks. Kororā chicks from the Oamaru Blue Penguin Colony were selected from both available sites and grouped based on their age at the time of sampling, 2 weeks old, 4 weeks old and 6 weeks old and a further two groups were formed for chicks that were handled twice a week from 2 weeks of age until 4 weeks or 6 weeks at which point they were sampled. Blood sampling and handling and capture stress responses were done following a modified standard protocol of a blood sample at 0 mins, 15 mins and 30 mins at which point they were returned to their nest to avoid over or under heating depending on the age and weather. The chicks being exposed to frequent human interactions were weighed twice a week and also had their flipper length and beak width, length and depth measured to graph the growth rates and body condition indices which has never previously been done in penguin chicks. It was found that frequent interactions with people did not have a significant effect on the stress responses when comparing previously handled chicks with unhandled chicks of the same age and that the previously handled chicks developed their adult-like stress response at a similar age to those that had not been previously handled. With regards to body condition indices and growth rates, this study showed that the parents leave the nest just after body condition indices drop to the low point in the chicks’ development.
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    The time course of corticosterone responses in kororā (little penguin, Eudyptula minor) : a thesis presented in partial fulfilment of the requirements of the degree of Master of Science in Zoology at Massey University
    (Massey University, 2017) Long, Kar Hui
    When birds and other vertebrates perceive a situation to be threatening the hypothalamopituitary-adrenal (HPA) axis is activated and glucocorticoid hormones are secreted from the adrenal gland. Activation of the HPA axis in response to a stimulus perceived to be threatening is called a stress response. The main glucocorticoid hormone in birds is corticosterone. Corticosterone responses of birds are typically measured by the collection of an initial blood sample when a bird is captured or picked up, then the collection of further blood samples until 30 to 60 minutes has elapsed, at which time the bird is released. Whilst this standard sampling protocol provides information on the size of the corticosterone response, it does not provide any indication of how long it takes for corticosterone concentrations to return to initial values. The main objective of this thesis was to characterise the total duration of the corticosterone response of free-living kororā (little penguins, Eudyptula minor). Little penguins at Oamaru were picked up from their nestboxes and initial blood samples collected. Birds were handled and then restrained by being placed in a box. Further blood samples were collected 15, 30 and 60 min after the birds were first picked up. Birds were then returned to their nest boxes and an additional blood sample collected 15, 30, 60, 120, 240, or 360 min later. Mean corticosterone concentrations declined to initial values two hours after birds were returned to nest boxes. The rates at which corticosterone concentrations increased when a stressor was present and then decreased when the stressor was no longer present were positively correlated. Seasonal changes in corticosterone responses in little penguins were also investigated in this study. Mean corticosterone responses were similar in winter and in the pre-laying period, whereas mean responses were lower in birds during early chick rearing. Corticosterone responses during the pre-laying period were greater in male than female little penguins. The current study is the first to document the complete corticosterone responses of free-living penguins and provides information about changes of corticosterone concentrations after a stressor is removed from the free-living individuals. It is also the first to reveal that free-living penguins with relatively high corticosterone responses to a stressor had relatively high rates of corticosterone decline.
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    Identification of novel proteins that potentially are in complex with Yih1 and that are required for promoting Gcn2 function : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Philosophy in Biochemistry at Massey University, Auckland, New Zealand
    (Massey University, 2015) Bolech, Michael
    The ability of organisms to respond to various stress conditions is important for life. Under amino acid starvation conditions the protein Gcn2 is activated and phosphorylates the translation initiation factor eIF2α. This leads to a downregulation of general protein synthesis and an upregulation of the synthesis of proteins that are involved in helping the cell overcome starvation, a process called General Amino Acid Control (GAAC). It is important that the GAAC is only switched on when necessary and for this Gcn2 needs to be regulated. For instance, the protein Gcn1 is needed for Gcn2 activation. Another protein, Yih1, inhibits Gcn2 activity by competing with Gcn2 for Gcn1 binding. However, the balance between Gcn2 activation by Gcn1 and Gcn2 inhibition by Yih1 is not well understood. Actin was already identified as a Yih1-binding protein and modelling exercises strongly suggests that additional proteins bind Yih1. The aim of this project was to identify novel proteins that are in a complex with Yih1 (Yih1-binding proteins, YBP) and to then discover which are required for Gcn2 activation. For the first aim, YBP were ascertained from published large-scale protein-protein interactions studies and from data generated in-house. 19 different strains deleted for one putative YBP exhibited an impaired growth under starvation conditions. Of those, four deletion mutants showed a reduced Gcn2 activity. One protein was Spc72 which is involved in mitochondrial organisation. Another protein was Idh2, an enzyme of the citric acid cycle. The growth defect of strains deleted for SPC72 or IDH2 was complemented with a plasmid containing SPC72 or IDH2, respectively, and other genes. This suggested their involvement in Gcn2 activation. Elongation factor eEF1A was found as a putative YBP and as a co-precipitator of Yih1, supporting previous unpublished observations. eEF1A was found to bind Gcn2 in previous studies and this suggested that Yih1-eEF1A interaction may regulate Gcn2 activation. Another putative YBP, the heat shock protein Hsc82, is needed for Gcn2 maturation. Strains deleted for HSC82 showed an impaired growth under starvation conditions and this was reversed by deleting YIH1. This suggested that Yih1 may regulate Hsc82-Gcn2 interaction and thus Gcn2 activity. This study was a step to further advance our understanding of Yih1-binding proteins and Gcn2 activity. In addition, this further emphasised the idea of Yih1 as an important regulator inside the cell.
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    Corticosterone responses to handling, and effects of corticosterone injections in the Japanese quail (Coturnix xoturni japonica) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University
    (Massey University, 2000) Boyd, Raewyn Anne
    These studies examined the effects of corticosterone on the reproductive system, investigated the relationship between plasma and faecal corticosterone levels and defined corticosterones response to handling in the Japanese quail (Coturnix coturnix japonica). Six days of daily corticosterone injections decreased the area of the cloacal protuberance in both seven week old and six month old male quail. However, plasma testosterone levels 24 hours after an injection were only decreased in the six month old birds. There was a strong correlation between basal plasma and faecal corticosterone concentrations in the six month old birds. The effects of corticosterone during the 24 hours after an injection were then examined before and after six days of corticosterone injections in male quail. Corticosterone injections decreased plasma testosterone levels three-fold for 6-12 hours both after a single corticosterone injection and after six days of treatment. However, there were no changes in plasma luteinising hormone levels during the 24 hours after an injection. This result is consistent with corticosterone acting directly on the testes to decrease testosterone release. The rate of corticosterone removal from the blood after an injection increased after six days of corticosterone injections. Handling female Japanese quail for 15 minutes resulted in increased plasma corticosterone levels for less than 30 minutes. Mean corticosterone response curves were almost identical when the same birds were handled on three occasions. Although corticosterone response curves were similar during the early afternoon and during the night, basal corticosterone levels and the area under the corticosterone response curves were lower at night. Plasma corticosterone levels 0 and 15 minutes after the initiation of handling were more than twice as high in birds with large gonads than birds with small gonads. This study provides the first information in birds of a decrease in plasma testosterone levels within three hours of a corticosterone injection, independent of changes in plasma LH levels. It is also the first study in a domestic species to show larger corticosterone responses in female birds with large gonads than in birds with small gonads.
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    Natural horsemanship : round-pen training of horses : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Physiology at Massey University, Palmerston North, New Zealand
    (Massey University, 2003) Mello, Philippa
    The effect of round-pen training on the behaviour and physiological response (plasma Cortisol concentration and heart rate) of 24 horses was examined using a stocks restraint stress test before, after and 3 weeks after round-pen training was carried out. Horses were allocated to treatment groups according to their ease of handling. Three treatment groups were formed, Control, Round-Pen Easy and Round-Pen Difficult (RP-D). Before the treatment (round-pen training or control) there were no significant differences between the three treatment groups for plasma Cortisol concentration and heart rate. Restraint in the stocks caused an elevation in plasma Cortisol concentrations in all horses. The increase in plasma Cortisol concentration was greater in the RP-D horses. A single round-pen training session was used as a treatment for the RP treated horses (Hasy or difficult). Post-treatment most horses had a significant decrease in the time to enter the stocks, however, treatment had no significant effect on the plasma Cortisol response, heart rate or behaviour of horses in each of the three treatment groups. Round-pen training sessions were observed to see if the ease of round pen training was affected by either dominance rank or the behaviours observed during round-pen training. Despite the individual variation between horses, all horses followed a similar pattern of behaviour during round-pen training. There was no significant effect of social status on the ease of round-pen training. The effect of dominance rank on the ease of handling, behaviours observed in the stocks and the plasma Cortisol concentration during the pre-treatment stocks tests were examined. Horses that occupied the lower ranks were less easy to handle during the pre-treatment stocks test. The occurrence of some agitation and rest behaviours differed between horses of high and low dominance ranks. Dominance rank had no significant effect on the resting plasma Cortisol concentration before treatment. Further research may clarify relationships between certain behaviours (head turning, head held up and defecation) and changes in plasma Cortisol concentration during restraint, that could be used as non-invasive indicators of the onset of stress in the restrained horse.