Tesis sobre el tema "Thermal physiological responses"

The aims of this project were to investigate the cellular stress response (CSR) in Enteromorpha spp. and assess the potential of the Stress-70 protein (an indicator of the CSR) as a biomarker of pollutant exposure and acquired tolerance in Enteromorpha spp., compared with conventional physiological endpoints of toxicity. Cross-reactivity of a commercial Stress-70 antibody with E. intestinalis proteins was determined and used to develop an assay for Stress-70. Using this assay E. intestinalis was found to exhibit a typical heat shock response. Stress-70 proved to be a relatively insensitive biomarker of copper exposure and did not appear to be involved in copper tolerance, the genetic basis of which was investigated by growing E. intestinalis using a novel culturing technique. Although growth was variable, it provided a simple, consistent and sensitive measure of copper toxicity. The chlorophyll fluorescence parameter Fv/Fm was insensitive to copper exposure. Nutrient limitation enhanced copper toxicity and significantly impaired growth, Fv/Fm and Stress-70 production in E. intestinalis. In both copper ‘sensitive’ and ‘tolerant’ E. intestinalis, copper exposure did not affect the ability to raise a heat shock response. In ‘sensitive’ algae, copper and heat shock were additive stressors, with heat shock acting as a stronger inducer of Stress-70. Only heat shock affected 'tolerant' algae. Zinc was less toxic than copper but in contrast to copper studies, Stress-70 was a relatively sensitive indicator of zinc exposure, compared to Fv/Fm and growth. Studies of triazine herbicides revealed that on a molarity basis, Irgarol 1051 was more toxic to E. intestinalis than atrazine. Fv/Fm and growth were strongly affected by Irgarol exposure, but Stress-70 levels were unaltered by exposure to the herbicide. Fv/Fm and Stress-70 were poor in situ biomarkers of pollution, but another chlorophyll fluorescence parameter - complementary area - appeared to correlate with levels of organic pollution. Overall, Stress-70 was found not to be a useful biomarker of exposure to copper or triazines in E. intestinalis, or in situ pollution. However, the Stress-70 assay developed has a number of alternative applications and Enteromorpha spp. were deemed to be potentially useful in pollution monitoring with the selection of suitable biomarker responses.

Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: As ectotherms, lizards are particularly vulnerable to changes in the thermal landscape and face extinction risk if they lack the capacity to rapidly adapt or behaviourally mitigate increasingly altered thermal environments. Theoretical models that predict lizards‟ response to climate change often fail to take into account the thermal characteristics of the microenvironment, the ability of lizards to behaviourally buffer climate variation in the habitat and the plastic nature of both behaviour and physiology over ecologically relevant time-scales. Here, I address this major knowledge gap using two separate research chapters in an experimental physiology approach. In Chapter 1, I investigated the temperature-dependence and plasticity of resting metabolic rate, water-loss rate and preferred body temperature of Cordylus oelofseni at several temporal scales (within and between seasons) and incorporated field observations to acquire a better understanding of this species‟ adaptive potential to buffer thermal changes in the habitat. Cordylus oelofseni showed plasticity of both behaviour and physiology in response to thermal acclimation, but relied on distinct strategies depending on the time-scale investigated. These results highlighted the complexity of underlying mechanisms used by these organisms to buffer temperature variation. In Chapter 2, I used an experimental approach to examine the energetic costs of thermoregulation in C. oelofseni and test the cost-benefit model of thermoregulation. This model‟s primary prediction states that lizards should thermoregulate carefully only when the associated costs are low. Using four enclosures that simulated different thermal qualities (temporal and spatial distributions of operative temperatures) in the habitat, I found limited support for the cost-benefit model. Lizards in the low-quality heterogeneous enclosures invested the same energetic effort and thermoregulated with similar overall accuracy as lizards in the high-quality heterogeneous enclosure. The costs incurred were not necessarily energetic, but reflected missed opportunities (e.g. less time to forage), something that, along with important interaction effects with body mass, deserves further attention when testing this model. Together, these results illustrate the importance of incorporating ecological reality at various time and spatial scales in order to make relevant predictions regarding the fate of lizards with projected climate change.
AFRIKAANSE OPSOMMING: As ektotermiese diere, is akkedisse veral sensitief vir veranderinge in die termiese landskap en staar uitsterwingsrisiko in die gesig as hulle nie die vermoë het om vinnig aan te pas of gedragsveranderinge te maak in omgewings wat toenemend verwarm nie. Teoretiese modelle wat akkedisse se reaksie op klimaatsverandering voorspel, neem dikwels nie die termiese eienskappe van die mikro-omgewing, die vermoë van akkedisse om met gedragsveranderinge klimaat variasie in die habitat te buffer en die plastieke aard van beide gedrag en fisiologie oor ekologies relevante tydskale in ag nie. Hier bespreek ek hierdie groot kennisgaping met behulp van twee afsonderlike navorsingshoofstukke in 'n eksperimentele fisiologie benadering. In Hoofstuk 1 het ek ondersoek ingestel na die temperatuur-afhanklikheid en plastisiteit van rustende metaboliese tempo, waterverlies tempo en voorkeur liggaamstemperatuur van Cordylus oelofseni by verskeie tydskale (binne en tussen seisoene) en inkorporeer veld waarnemings om 'n beter begrip te verkry van hierdie spesie se aanpasbare potensiaal om termiese veranderinge in die habitat te buffer. Cordylus oelofseni het plastisiteit van beide gedrag en fisiologie in reaksie op hitte-akklimatisering getoon, maar staatgemaak op verskillende strategieë, afhangende van die tyd-skaal wat ondersoek is. Hierdie resultate beklemtoon die kompleksiteit van die onderliggende meganismes wat gebruik word deur hierdie organisme om temperatuur verandering te buffer. In Hoofstuk 2 het ek 'n eksperimentele benadering gebruik om die energiekoste van termoregulering in C. oelofseni te ondersoek en die kostevoordeel model van termoregulering te toets. Hierdie model se primêre voorspelling verklaar dat akkedisse slegs versigtig moet termoreguleer wanneer die gepaardgaande koste laag is. Deur gebruik te maak van vier afskortings wat verskillende termiese eienskappe gesimuleer het (tyd en ruimtelike verspreiding van operatiewe temperature) in die habitat, het ek beperkte ondersteuning gevind vir die koste-voordeel model. Akkedisse in die lae-gehalte heterogene afskortings het dieselfde energieke moeite belê en getermoreguleer met soortgelyke algehele akkuraatheid as akkedisse in die hoë-gehalte heterogene kamp. Die kostes wat aangegaan is, is nie noodwendig energiek nie, maar weerspieël geleenthede wat gemis is (bv. minder tyd om kos te soek), iets wat, saam met belangrike interaksie effekte met liggaamsmassa, verdere aandag verdien wanneer hierdie model getoets word. Tesame illustreer hierdie resultate die belangrikheid van die integrasie van ekologiese werklikheid op verskillende tyd en ruimtelike skale, om relevante voorspellings oor die lot van akkedisse met geprojekteerde klimaatsverandering te kan maak.

The work described in this thesis was conducted to assess the contribution psychological skills training (PST) including goal-setting, relaxation strategies, mental imagery and positive self-talk, can make to the capability to suppress or tolerate the physiological responses to thermally stressful environments. PST, a technique originally developed in sport psychology studies, was specifically tailored to aid individuals in adverse conditions, thereby providing some insight in to the contribution psychological factors can make to survival. This approach was designed to provide some idea of the contribution the will to survive may make in hazardous and threatening circumstances. We hypothesised that psychological training could significantly alter the responses elicited by thermal stimuli. The assumption was that psychological skills that have proven to be efficacious under psychological and physiological stress in challenging sporting environments, could also prove influential in more hazardous thermal environments. Study I examined the influence of mental imagery on the vasomotor responses to thermoneutral (26-28°C), cool (12.5°C) and warm (40°C) air in twelve healthy male subjects. We assessed whether hot and cold mental images could alter peripheral vasomotor tone and thermal perception in these environments. This study was conducted to quantify the influence of a psychological skill whilst at rest and in an environment with few external stimuli. Comparisons between control and mental imagery periods (hot and cold), both before and after mental imagery training, suggested that a single psychological skill has a limited capacity to alter the largely involuntary vasomotor responses to thermoneutral, cool, and warm air as only transient and insignificant effects were observed. There is also only a limited impact of this type of mental practice on thermal perception in a thermoneutral (26-28°C) environment. The null hypothesis was therefore accepted. The subsequent study (study 2) examined the impact of a package of psychological skills on the responses that are recognised as being under greater voluntary control at rest, but have been thought to be involuntary following acute cold-water stimulation, namely breath-holding. This study involved 32 healthy male subjects completing two immersions into cold-water (I VC), an activity that significantly reduces maximal breath-hold time and that can be a precursor to drowning following accidental immersion. On immersion the subjects were required to breath-hold for as long as possible. Following an initial breath-hold immersion subjects were ranked in order of lowest to highest breath-hold time (BHwater,), and allocated to either a control group (CG: BRm, r time mean [s. d]; n= 16: 24.01 [6.72] sec) or a psychological intervention group (PIG: n= 16: 24.66 [14.60] sec). Over the 7-day period between immersions the CG continued normal daily activity whereas the PIG completed five 1-hour PST sessions comprising goal-setting, relaxation strategies, mental imagery and positive self-talk; the final session provided a summary of the first 4 skills. Subjects then completed a second breath-hold immersion during which the PIG recorded a significantly longer breath-hold time after psychological intervention compared to the CG (BH_water4: 4.25 [31.63] sec; CG: 21.34 [16.3 1 ]; P=0.026). PST conferred an almost 80% improvement in BH_water suggesting psychological factors may significantly influence the respiratory responses to cold-water immersion providing the first indication of the influence of mental 'will' in such conditions. Study 3 examined the impact of PST on maximal BH_water following coldhabituation, thus assessing the extent to which habituation to cold water includes a conscious psychological component. Twenty healthy, non-habituated male subjects completed an initial immersion into cold-water (I2°C whilst breath-holding (BH_water) and were subsequently matched and allocated to one of two groups, a habituation only group (HAB, n= 10: BHwater22.00 [10.33] sec) and a habituation plus PST group (H-PST, n= 10: 22.38 [10.65]sec). In the interim period (7-10 days) between breath-hold immersions all subjects completed 5 free breathing immersions into cold-water (12°C). In addition, the H-PST group completed the same PST intervention as used in study 2, aimed at consciously increasing maximal BH_water time on immersion. After their respective interventions all subjects completed a second breath-hold immersion. Results showed that the habituation regimen significantly reduced the cardiorespiratory responses to immersion in both groups by a similar magnitude. Significant changes took place in both groups by the 4^th habituation immersion. Statisicial analysis showed no significant differences between groups in BH_water (P = 0.299) indicating PST did not have a significant and additive effect upon the ability to breath-hold on immersion after habituation (HAB, n= 10:BH_water 36.31 [23.88] sec; H-PST, n= 10: 49.25 [30.87]). Study 4 examined the influence of a PST package on the voluntarybehavioural responses to prolonged thermal stress whilst exercising (30°C for 90minutes). Eighteen subjects completed a total of 3 exercise trials in the heat in whichthey were required to run as far as possible on a treadmill until exhaustion occurred,or the allotted time expired. Following trial 2 subjects were matched and allocated toeither a CG or PIG based on the variability in run performance shown between trial Iand 2. The groups alos did not significantly differ based on maximal oxygen uptake,or sum of skinfold (s. o. s) measurement but were not matched on these criteria. As with study 2, the CG continued normal daily activity between trials 2 and 3 whereas the PIG completed a version of the previously used PST package tailored to help them cope with the unpleasant sensations associated with elevated deep body temperature and prolonged exercise in the heat. Inter-trial variability was 1.70 [2.82]% between trial I and 2 in the CG versus 0.98% [5.28] in the PIG. Between trial 2 and 3 the CG improved by 2.74% [4.03] whereas the PIG ran 6.88% [5.82] further in trial 3. In percentage terms, the PIG ran significantly further in trial 3. The mechanism underpinning the change in performance in the PIG was not statistically linked to any of the physiological variables measured. Overall, the findings suggest PST may also influence the capacity to tolerate the unpleasant physiological responses to exercise in the heat, but were less influential than in the cold. The possible mechanisms underpinning the changes that take place with PSTare considered. It is concluded that psychological skills training significantlyinfluenced the physiological responses over which there is greatest voluntary controlThe present work demonstrates the potential role psychological factors may play in surviving certain conditions and scenarios which involve the choice to tolerate or suppress the evoked responses to thermal stimuli or, to succumb to the environmental conditions. The distinction between individuals in making this choice may be a product of mental will and provides the first evidence that the will to survive may have some genuine foundation between being a victim or a survivor following accidental exposure.

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Um sistema de medição e controle foi desenvolvido para o estudo de respostas fisiológicas de aves sujeitas a mudanças térmicas como meio de alívio de estresse térmico. O sistema faz o controle automático da temperatura (t a,SP ±0,2 oC) e da umidade relativa do ar (RH SP ±2 %); sendo que a velocidade do ar foi controlada manualmente (V SP ±0,1 m· s -1 ); e contínuo armazenamento das termografias (ex., temperatura superficial, t surf ) e da temperatura corporais (t b ) dos animais. As condições térmicas controladas na zona de ocupação animal (AZO) são atingidas pela operação de um pequeno túnel de vento (V = 0 to 1,5 m· s -1 ) colocado no interior de uma sala ambiental com t a e RH controlados (5,0 m comprimento × 3,5 m largura × 3,0 m altura). Os valores desejados de t a e RH foram alcançados por meio de aquecedores e umidificadores controlados em dois estágios via um módulo de controle e medição programável, e periféricos. Termografias (discernabilidade de 0.06°C) são adquiridas com uma camera infravermelho cuja operação é controlada remotamente por um PC. t b (±0.1°C) é armazenado em uma unidade de telemetria, sem a necessidade de intervenção cirurgica, que também é conectado a um PC. Em adição, um sistema de video tem sido usado para observar e arquivar os comportamentos do animal. A instrumentação desenvolvida foi usada em um experimento para ajustar equações empíricas para descrever as necessidades de molhamento parcial da superfície em galinhas poedeiras (Hy-Line W98, com 34 ± 1 semanas) sujeitas a condições de estresse térmico. A água necessária para limitar o aumento da temperatura superficial das galinhas foi expressada em termos de intervalo de aspersão (SI 10 , min) para uma dosagem constante (10 ml· aspersão -1 ) ou para uma taxa de evaporação (ER, ml.min -1 ) de água aspergida. As exposições térmicas consistiram de uma combinação fatorial de 3 temperaturas de bulbo seco (t db ) (35, 38 e 41 °C) x 2 temperaturas de ponto de orvalho (t dp ) (21,1 e 26,7 °C) x 3 velocidades do ar (V) (0,2, 0,7 e 1,2 m· s -1 ). As condições ambientais foram expressas como 18 combinações de déficit de vapor de pressão do ar (VPD air ) x V. ER foi diretamente proporcional ao produto VPD air · V . As relações podem servir como a base para a otimizar o sistema de resfriamento superficial intermitente para alívio de estresse térmico em galinhas criadas em gaiolas. Ademais, um índice de desconforto térmico (TDI) foi derivado com base nas respostas fisiológicas, temperatura superficial (t surf ) e temperatura corporal (t b ), de galinhas sujeitas a exposições térmicas. Com base no aumento da t b aos 50 min de exposição térmica (Δt b,50 ), um TDI foi relacionado ao VPD air e a V da seguinte forma: TDI = -15.17 + 18.62 (t db ) n – 0.92 · (VPD air · V ) n . Usando TDI, quatro zonas de desconforto térmico (segura, alerta, perigo e fatal) foram definidas para as várias combinações de condições térmicas. Um modelo teórico de transferência de calor e massa em regime transiente também foi proposto para predizer Δt b,50 em função das condições ambientais, das condições fisiológicas das aves e do nível de molhamento (β). O modelo proporciona uma ferramenta conveniente e interativa para determinar Δt b,50 nas galinhas submetidas ou não ao molhamento superficial para t db variando de 35 a 38 °C.
A control and measurement system was developed for studying physiological responses of poultry to thermal challenges and means of thermal stress relief. The system features automatic control of air temperature (t a,SP ±0.2 oC) and relative humidity (RH SP ± 2 %); manual setting of air velocity (V SP ± 0.1 m· s -1 ); and continuous recording of thermographs (i.e., core body temperature (t b ) of the animal. surface temperature, t surf ) and The controlled thermal conditions in the animal-occupied zone (AOZ) are achieved through operation of a small wind tunnel (V = 0 to 1.5 m· s -1 ) inside a t a - and RH-controlled environmental room (5 m L × 3.5 m W × 3.0 m H). Target t a and RH values are achieved by controlling auxiliary heaters and humidifiers in two stages via a programmable measurement and control module and peripherals. Thermographs (0.06°C discernability) are acquired with an infrared (IR) imager whose operation is remotely controlled by a PC. Core body temperature (t b , ±0.1°C) is recorded with a surgery-free telemetric sensing unit that is also interfaced with a PC. In addition, a video monitoring system is used to observe and archive animal behaviors. The instrumentation developed was used in an experiment to establish empirical equations to describe the need of partial surface wetting for cooling laying hens (Hy-Line W-98, 34 ±1 wk old) subjected to a range of thermal stress conditions. The thermal exposures consisted of a factorial combination of 3 dry bulb temperatures (t db ) (35, 38 and 41 °C) × 2 dew point temperatures (t dp ) (21.1 and 26.7 ° C) × 3 air velocities (V) (0.2, 0.7 and 1.2 m· s - ). The environmental conditions were expressed as 18 combinations of air vapor pressure deficit (VPD air ) × V. The water necessary to limit hen surface temperature from rising was expressed in terms of sprinkle interval (SI 10 , min) for a constant spray dosage (10 ml· spray -1 ) or evaporation rate (ER, ml· min -1 ) of the sprayed water. ER was directly proportional to VPD air · V . The relationships may serve as the basis for optimizing an intermittent partial surface cooling system for thermal stress relief of caged layers. Also from the study, a thermal discomfort index (TDI) was derived based on physiological responses, surface temperature (t surf ) and core body temperature (t b ) of the control (non-cooled) hens. Based on t b rise after 50 min of thermal exposure (Δt b,50 ), TDI related to VPD air and V as: TDI = -15.17 + 18.62 (t db ) n – 0.92· (VPD air · was V ) n . Using TDI, four zones of thermal discomfort (safe, alert, danger, and fatal) were defined for various combinations of thermal conditions. Furthermore, theoretical transient heat and mass transfer model was proposed to predict Δt b,50 as a function of environmental conditions, physiological responses of the hens and surface wetness level (β). The model provides a convenient, interactive tool for determining Δt b,50 on wetted and non-wetted hens for t db ranging from 35 to 38 °C.

Regional differences in sweat gland output, skin temperature and thermoreceptor distribution can account for variations in regional perceptions of temperature, thermal comfort and wetness sensation. Large cohorts of studies have assessed these perceptual responses during sedentary activity but the findings are typically applied to a multitude of conditions, including exercise. Increases in sweat gland output, redistribution of blood flow and changes in skin and core temperature are basic responses to exercise in most conditions and these ultimately influence our perceptual responses. The primary aim of this thesis is to determine factors that influence regional differences in thermal sensation, thermal comfort and wetness sensation during exercise in moderate to hot conditions. The secondary aim is to develop and understand an additional variable, galvanic skin conductance (GSC) that can be used to predict thermal comfort and wetness sensation. The aim of the first study (Chapter 4) was to determine the influence of exercise on thermal sensitivity and magnitude sensation of warmth to a hot-dry stimulus (thermal probe at 40°C) and assess if any gender-linked differences and/or regional differences exist. From the data, body maps indicating sensitivity were produced for both genders during rest and exercise. Females had more regional differences than males. Overall sensitivity was greatest at the head, then the torso and declined towards the extremities. The data showed that exercise did not cause a significant reduction in thermal sensitivity but magnitude estimation was significantly lower after exercise for males and selected locations in females. The cause of a reduced magnitude sensation is thought to be associated with exercise induced analgesia; a reduction in sensitivity due to exercise related increases in circulating hormones. As the literature suggests that thermal comfort in the heat is influenced by the presence of sweat, the next study and all proceeding studies were concerned with this concept. In Chapter 5, building on earlier studies performed in our laboratories, the influence of local skin wettedness (wlocal) on local thermal comfort and wetness sensation was investigated in a neutral dry condition (20.2 ± 0.5°C and 43.5 ± 4.5% RH) whilst walking (4.5 km∙hr-1). Regional differences in wlocal were manipulated using specialised clothing comprising permeable and impermeable material areas. Strong correlations existed between local thermal comfort and local wetness sensation with the various measured wlocal (r2>0.88, p<0.05 and r2>0.83, p<0.05, respectively). The thermal comfort limit was defined as the wlocal value at which the participants no longer felt comfortable. Regional comfort limits for wlocal were identified (in order of high-low sensitivity); lower back (0.40), upper legs (0.44), lower legs (0.45), abdomen (0.45), chest (0.55), upper back (0.56), upper arms (0.57) and lower arms (0.65). The maximum degree of discomfort and wetness sensation experienced during the investigation was kept deliberately low in an attempt to determine the threshold values. Therefore comfort scores and wetness scores rarely reached a state of uncomfortable or wet so the next step was to assess these relationships when sweat production is high and the sensations worsened. However, pilot testing indicated that a ceiling effect would occur for wlocal at high levels of sweat production whilst thermal discomfort increased indicating wlocal was not the determining parameter in that case. Thus an additional parameter was required. The chosen parameter was galvanic skin conductance (GSC) due to its alleged ability to monitor pre-secretory sweat gland activity, skin hydration and surface sweat. In Chapter 6, the reliability, reproducibility and validity of GSC were confirmed in a series of pilot tests. Moderate to strong correlations were found between GSC and regional sweat rate (RSR) (r2>0.60, p<0.05) and wlocal (r2>0.55, p<0.05). The literature suggests standardising GSC relative to a minimum and maximum GSC value; however uncertainties arise when attempting to achieve maximum GSC. Therefore a change from baseline (∆GSC) was chosen as the proposed method of standardisation for further use. Additional results (from Chapter 9) revealed that ∆GSC also reflects pre-secretory sweat gland activity as it increased prior to sweat being present on the skin surface and prior to an increase in RSR. In Chapter 9, also hydration of the stratum corneum was measured using a moisture meter and the results revealed that it has an upper limit; indicating maximal hydration. From this point of full skin saturation ∆GSC and RSR markedly increase though sensations did not. It was also found that ∆GSC is only influenced by surface sweat that is in direct contact with the electrode and is not influenced by sweat elsewhere on the skin surface between electrodes. Higher levels of thermal discomfort have rarely been explored and neither has its relationship with wlocal. The ability of ∆GSC and wlocal to predict local thermal comfort and wetness sensation were compared in two different conditions to elicit low and high sweat production. Unlike Chapter 5, the body sites were not manipulated to control wlocal but allowed to vary naturally over time. The test was carried out on males (Chapter 7) and females (Chapter 8) to compare any gender linked differences and the results suggest that females are more sensitive than males to the initial presence of sweat. For both genders, wlocal and ∆GSC are strong predictors of thermal comfort and wetness sensation. More importantly, wlocal can only be used to predict local thermal comfort in conditions of low sweat production or low levels of thermal discomfort. However, once sweat production increases and thermal discomfort worsens ΔGSC (and not wlocal) can predict thermal comfort. Due to low sweat production observed in females indicates that this is only relevant for females. It appears that epidermal hydration has an important role on influencing thermal comfort. Receptors influencing our perceptual responses are located in the epidermis and when sweat is produced and released onto the skin surface, this epidermis swells and the sensitivity of receptors are said to increase. wlocal indicates the amount of moisture present on the skin surface, yet ∆GSC indicates presecretory sweat gland activity and epidermal hydration where the receptors are located. This may explain why on numerous occasions thermal comfort had a stronger relationship with ∆GSC than wlocal. Where Chapter 5 indicated the true local comfort limits for each respective zone, Chapter 7 and 8 provided a global picture of how local regions interact and influence local thermal comfort across the body. When wlocal varies naturally, the torso areas naturally produce more sweat than the extremities and it seemed that these areas produce so much more sweat than the extremities that they dominate local thermal comfort across the whole body. This is referred to in this thesis as a model of segmental interaction. As with thermal comfort, wetness sensation had strong relationships with wlocal and ∆GSC. The results also revealed a strong relationship between wetness sensation and thermal comfort. In contrast to the widely supported claim, a drop in skin temperature is not required to stimulate a wetness sensation. The point at which we detect sweat and when it becomes uncomfortable occurs at different wlocal values across the body. Thermal comfort is shown to be influenced by sweat during exercise in moderate-to-hot conditions. As w has an upper limit the findings suggest that it cannot predict thermal comfort during high sweat rates. Galvanic skin conductance monitors the process of sweat production more closely and thus is a better predictor of thermal comfort during all conditions and particularly during high sweat production. The strong relationship between thermal comfort and wetness sensation confirm the role of sweat production on thermal comfort. Gender differences to perceptual responses were observed, with females generally being more sensitive to sweat and a warm thermal stimulus than males. Regional differences to sweat and a warm stimulus generally suggest that the torso area is more sensitive than the extremities. This is important not only for sports clothing design but also protective clothing at the work place.

During the past several decades, corals worldwide have been dealing with a considerable increase in water temperature due to climate change, which is predicted to increase the frequency of coral bleaching and mass mortality events. Nevertheless, corals show differences in stress susceptibility and they are not all affected evenly. The symbiotic coral Oculina patagonica from the Eastern Mediterranean Sea can thrive in relatively unstable environments and is considered a stress-tolerant species. In this study, baseline expression and temporal dynamics of induction of a 70-kDa heat shock protein (HSP70) after an acute heat stress were analyzed in O. patagonica to investigate the influence of its peculiar physiological traits on stress responsiveness. Furthermore, data collected were further discussed within a comparative analysis with similar findings reported in 5 temperate corals of the Mediterranean Sea (Franzellitti et al., 2018). Results show that O. patagonica hsp70 transcriptional response aligns with the formerly observed high resistance for elevated sea water temperatures of this species. The multispecies comparison shows that hsp70 expression varies in accordance with the stress sensitivity of coral populations inhabiting different thermal environments and possessing different trophic strategies and morphologies. This study also reports an analysis of the post heat-stress transcriptional regulation of transcripts related to energy metabolism (gadph), redox regulation (sod), and DNA damage (bcl-2 and bax), disclosing the time line of the events occurring in O. patagonica in response to an acute heat stress, which aligns with its quick recovery from bleaching. These molecular processes analysis is particularly demanding for corals inhabiting the Mediterranean Sea, in light of projected scenarios of anthropogenic global change.

Six sites within the Denton and Hickory Creek watersheds were sampled over three years to assess the impact of seasonal intermittent stream conditions on the ichthyofauna. An integrated approach using field and laboratory techniques was employed to evaluate the responses of the fishes.

Low oxygen tolerances of ten fishes were estimated using an original nitrogen cascade design, and reciprocally transformed to express responses as ventilated volume necessary to satisfy minimal oxygen demand (L·mg O2^-1). Values ranged from 0.52 to 5.64 L·mg^-1 and were partitioned into three statistically distinct groups. Eight stream fishes showed moderately high tolerances reflecting metabolic adaptations associated with stream intermittency. Juvenile longear sunfish and two mollies comprised the second group. High tolerance of hypoxia may allow juvenile sunfish to avoid predation, and mollies to survive harsh environmental oxygen regimens. The sheepshead minnow was the most tolerant species of low oxygen, of those examined, explaining its presence in severely hypoxic environments.

This dissertation evaluated nutritional approaches such as the addition of betaine, prebiotics, probiotics, transitional metabolic substrates, and β-mercaptoacetate (MAA; a compound which inhibits β-oxidation) to the diet of lactating dairy cows to determine their impact on physiological, metabolic, hormonal and production responses during thermal stress. The first objective was to evaluate the use of an organic osmolyte, betaine to reduce the impact of heat stress (HS). Cows were fed either 0 (control; CON), 57 mg/kg BW (mid) or 114 mg/kg (high; HI) body weight (BW) betaine and subjected to thermoneutral (TN) and HS conditions. There was an increase in milk yield during TN with HI betaine over controls (P< 0.01), but the advantage was lost during HS. Plasma glucose increased during HS in HI dose cows compared to control (P < 0.01) as did plasma insulin (P = 0.01). Betaine increased milk production during TN and plasma glucose in HS, but did not improve the HS response. Objective two evaluated the use of a probiotic or direct fed microbial (DFM), Calsporin (Bacillus subtilus C-3102) to decrease the effects of HS in dairy cows. We hypothesized that feeding Calsporin prior to and during HS would reduce pathogenic strains of bacteria, maintain commensal microbes, and improve ruminal anaerobic fermentation resulting in improved milk yield (MY). Milk yield was numerically increased (1.26 kg, P = 0.11) in cows fed Calsporin during TN but was reduced under HS (-2.67 kg, P < 0.01) and milk protein content was decreased (P = 0.05). The DFM tended to decrease somatic cell count (SCC) across periods (P = 0.07). Calsporin addition to the diet did not affect respiration rates and was associated with higher rectal temperature at 1800 in HS (P = 0.02). The expression of heat shock protein 27 (HSP27) was decreased with Calsporin treatment (P = 0.03) and in both HS and TN. The fecal microbial count did not change with the exception of the Calsporin strain in treated animals (P < 0.01). The third objective was to feed OmniGen-AF (OG) to dairy cows before and during thermal stress. We hypothesized that feeding OG to HS dairy cows will improve the immune response, and decrease production losses associated with HS. Cows fed OG maintained lower SCC compared to control (P < 0.01) during the recovery period. We did not detect differences between groups in serum calcium while serum non-esterified fatty acid (NEFA) concentrations (P = 0.10) tended to be greater in OG fed cows across the Agricultural Research Center (ARC) portion including HS. Serum Adrenocorticotropic hormone (ACTH) levels were greater in OG cows (P<0.0001) across all sample days. Feeding OG reduced the HS response including serum Cortisol. The final study measured the effects of the metabolic substrate β-hydroxybutyrate (BHB) during HS on feed intake and metabolites. Under TN conditions the cows received a bolus dose of BHB and dry matter intake (DMI) and metabolites were measured. The second part of this study used a bolus of MAA to limit the up-stream production of acetyl-CoA available for ketogenesis by inhibiting ß-oxidation. We proposed that dosing lactating dairy cows with BHB would decrease DMI, increase plasma insulin, decrease NEFAs and increase skin temperature by vasodilatation. The same cows were then subjected to HS and dosed with saline and MAA on different test days. The infusion of BHB increased skin temperature (time 0.5, 1, 2, 3 and 4°C r² =0.98 with serum BHB) and decreased serum NEFA levels (P < 0.01). There was no change in mean DMI, glucose or insulin. The bolus of MAA decreased feed intake, vaginal temperature, and insulin. There was an increase in serum BHB with the initial dose of MAA and an initial decrease in serum glucose (P < 0.0001) with MAA. Serum glucose increased as insulin decreased with MAA. The infusion of BHB did not alter feed intake in this study despite high plasma levels of BHB.

Les scénarios de changements globaux sont précieux pour guider les stratégies de gestion et de gouvernance, inciter à la prise de décision et augmenter la prise de conscience collective des tendances futures de la biodiversité. Le degré de réalisme et d'intégration des modèles écosystémiques utilisés à cet effet est en constante progression, mais ils négligent encore souvent l'évolution des populations marines dans les projections futures. Or, celles-ci s'adaptent aux changements globaux, que ce soit par la plasticité phénotypique ou l'évolution, au travers de modifications de leurs caractéristiques biologiques telles que les traits d'histoire de vie, physiologiques et bioénergétiques. L'enjeu de cette thèse est de développer un modèle écosystémique qui permette d'explorer des scénarios de biodiversité aux échelles intra- et inter-spécifiques en représentant explicitement la plasticité phénotypique des traits d'histoire de vie, leur variabilité génétique, leur sélection et leur évolution sous l'influence combinée de la pêche et du changement climatique, ainsi que la dérive génétique et la perte de diversité génétique qui en résultent. Appliqué à la mer du Nord, ce nouveau modèle est utilisé pour comprendre les processus responsables des changements de traits d'histoire de vie qu'ils soient d'origine plastique ou d'origine évolutive. D'une part, les processus bioénergétiques sous-jacents aux changements plastiques sont étudiés par une approche originale comparant les différences entre les courbes de réponses thermiques fondamentales et réalisées pour différentes espèces et stades du cycle de vie. D'autre part, les changements des traits d'histoire de vie sont explorés à travers le prisme de l'évolution grâce à la prise en compte de pressions de sélection multiples telles que la pêche, les interactions proies-prédateurs et le changement climatique.L'intégration des processus plastiques et évolutifs dans les modèles écosystémiques permet de décrire la variabilité interindividuelle des traits biologiques et de comprendre leurs tendances temporelles observées dans le milieu marin. En cela, elle répond à l'enjeu crucial de crédibilité des projections de la biodiversité intra- et inter-spécifique sous scénarios combinant climat et pêche. L'intégration de ces processus permettra également de quantifier plus précisément les effets synergiques et antagonistes de ces deux pressions et de prendre en compte la capacité d'adaptation des populations aux changements globaux pour estimer de manière plus fiable leur résilience
Global change scenarios are valuable for guiding management and governance strategies, stimulating decision making, and increasing collective awareness of future biodiversity trends. The degree of realism and integration of ecosystem models used for this purpose is constantly improving, but they still often neglect the evolution of marine populations in future projections. However, marine populations adapt to global changes, either through phenotypic plasticity or evolution, through modifications of their biological characteristics such as life history traits, physiological and bioenergetic traits. The challenge of this thesis is to develop an ecosystem model that allows the exploration of biodiversity scenarios at intra- and inter-specific scales by explicitly representing the phenotypic plasticity of life history traits, their genetic variability, selection and evolution under the combined influence of fisheries and climate change, and the resulting genetic drift and loss of genetic diversity. Applied to the North Sea, this new model is used to understand the processes responsible for changes in life history traits, whether they are of plastic or evolutionary origin. On the one hand, the bioenergetic processes underlying plastic changes are studied by an original approach comparing the differences between the fundamental and realized thermal response curves for different species and life history stages. On the other hand, changes in life history traits are explored through an evolutionary lens by taking into account multiple selection pressures such as fishing, prey-predator interactions and climate change.The integration of plastic and evolutionary processes in ecosystem models allows to describe the inter-individual variability of biological traits and to understand their temporal trends observed in the marine environment. In this way, it responds to the crucial issue of credibility of intra- and inter-specific biodiversity projections under scenarios combining climate and fisheries. The integration of these processes will also allow to quantify more precisely the synergistic and antagonistic effects of these two pressures and to take into account the capacity of populations to adapt to global changes in order to estimate more reliably their resilience

碩士
國立臺灣師範大學
生命科學研究所
102
Corals and their symbiotic algae (genus Symbiodinium), collectively known as coral holobionts, live close to their physiologically-limit of sea surface temperature (SST) between 28 0C to 30 0C in the tropical and subtropical water. Increasing of 0.5-1 0C above the sea surface temperature (SST) will cause physiological stress of coral holobionts and, as the consequence, breakdown of symbiotic relationship (also known as “bleaching”). Understanding how coral holobionts with different SST “background” respond to the thermal stress is the key to identify the strategies of future survival of coral holobionts and function of coral reef ecosystem under the impact of climate change. In this study first conducted Symbiodinium diversity surveys of Porites corals from the Bietou (BT) in the northern Taiwan and Nuclear power plant outlet (OL) of Kenting National Park, in southern Taiwan, where yearly mean SST 23.8 ± 3.8 0C and 27.5 ± 1.7 0C, respectively. 37 coral samples were examined, C15, C55, C55-1, and six C15-related new Symbiodinium types were identified in Porites. A significant difference in Symbiodinium type compositions was found in Porites between BT and NPP-OL with the six C15-related types dominant in BT. Analysis of the maximum quantum yield (Fv / Fm) in Porites exposed to different temperature treatments in the tanks showed that Porites of NPP-OL was more sensitive to the thermal treatments than those of the BT during thermal stress. In addition, NPP-OL Porites collected from 7 m displayed a significantly higher Fv / Fm than those from 3 m, which might due to difference of the host species. Analysis of Symbiodinium density and chlorophyll pigments concentration showed that BT population displayed higher concentration of chlorophyll pigments than OL population. However, NPP-OL population increased Symbiodinium density instead of chlorophyll pigments when facing thermal stress. Results from this thesis suggested that Porites living in different thermal background could associate with different Symbiodinium C15-related types. Meanwhile, different C15-related types might have variety of photosynthesis responses in assisting coral hosts to survive under the thermal stress caused by rising sea surface temperature.

This study examined the metabolic and thermal responses of 14 firefighters during four repeated work bouts of treadmill exercise in a thermoneutral laboratory, working at an intensity similar to typical firefighting tasks (30-34 ml·kg-1·min-1), while wearing firefighting protective equipment and breathing from a self-contained breathing apparatus. Each work bout consisted of treadmill walking at 93.8 m·min-1 and 8% grade for 8 min followed by 4 min of passive rest. Oxygen consumption remained unchanged between all four work bouts (p>0.05). Ventilation increased significantly (p<0.05) during the first three work bouts from 57.1 (±3.1) to 68.7 (±2.7) L·min-1. Percent heart rate reserve increased significantly (p<0.05) during each work bout, from 76.0 (±1.8) % HRR during the first to 97.2 (±1.1) % HRR during the fourth work bout. Core temperature increased significantly (p<0.05) during each work bout from 36.87 (±0.07) to 38.87 (±0.10) °C from the first to the fourth work bout, as did some of the psychophysiological measures.

Very little is known about the metabolic and biochemical physiology of spiny lobsters as they develop. An improved understanding of the physiological responses of spiny lobsters to different environmental and culture conditions during ontogeny is essential for gaining a better understanding of environmental influences on wild populations and for their successful propagation. This study addresses important gaps in our knowledge by examining stage-specific changes in metabolic rates, ammonia-N excretion rates, thermal tolerance thresholds, and whole body and haemolymph biochemistry of larval and juvenile Sagmariasus (Jasus) verreauxi in order to observe these physiological parameters through ontogeny. Automated intermittent flowthrough respirometry was used to measure the aerobic metabolism of larval and juvenile lobsters accurately. Whole body biochemical analysis was used to examine energy storage and utilisation of phyllosoma. Haemolymph biochemistry was used to determine the thermal tolerance thresholds of juvenile lobsters. The effect of temperature change on the final instar (instar 17) was examined to assess whether it could serve as a cue for metamorphosis and it was found that temperature affected routine metabolic rate (`R_r`), but did not alter instar duration, and therefore is not a cue for metamorphosis. Fewer phyllosoma, however, completed metamorphosis and progressed to the puerulus stage at sub-optimal warm temperatures compared to cooler temperature. The effect of culture density was examined from hatch to pueruli. High culture density reduced growth (dry mass) and development (moult increment) of phyllosoma. There was a shift in metabolism via energy storage and utilisation of instar 17 phyllosoma in preparation for the morphological changes associated with metamorphosis. There was also an accumulation of lipid reserves during larval development that fuelled metamorphosis and the non-feeding puerulus stage. The aerobic scope of juvenile lobsters was determined through chasing lobsters by hand until the lobster was exhausted and did not respond to further stimuli along with the effects of handling, anaesthesia, and activity on the oxygen consumption rate (`ṀO_2`) and ammonia-N excretion rate. Handling caused a relatively minor increase in `ṀO_2` and anaesthetics reduced activity of lobsters, but did not reduce `ṀO_2` or recovery periods from force feeding or handling. S. verreauxi juveniles have a narrow aerobic scope. Increased `ṀO_2` from anaesthesia and activity uses a large proportion of energy within the metabolic scope that could otherwise be utilised for other physiological functions. Thermal tolerance thresholds were examined in different sized juvenile lobsters. Sudden changes in haemolymph `O_2` concentrations with water temperature indicated large lobsters have a higher optimum water temperature than small lobsters. Maximum attainable rates of standard metabolism indicated the upper critical temperature (`T_c`) for juvenile S. verreauxi, characterised by the onset of anaerobic metabolism. Juveniles utilised lipid as an energy substrate at optimal temperatures, but shifted towards protein catabolism at temperatures above their thermal tolerance range. This research revealed the long larval phase of S. verreauxi is essential for accumulating lipid reserves to fuel later larval stages and provided a more complete picture of the environmental and culture requirements of spiny lobsters during ontogeny, particularly for the rarely studied late phyllosoma stages. It also established that induced stress uses a large proportion of the aerobic scope in juvenile lobsters, which limits their ability to perform aerobically and deal with additional physiological challenges. The thermal tolerance of S. verreauxi juveniles identified the potential to expand their geographic distribution, which may have a large impact on benthic community structures and dynamics through competition for resources with existing lobster populations and other animals within the ecosystem. This may also impact local economies, particularly valuable local southern rock lobster fisheries.

Listeria monocyto genes is a facultative anaerobic pathogen found in soil and water, on vegetation, food contact surfaces and in raw food materials including seafood. It grows at refrigeration temperatures and up to 14% sodium chloride making it almost impossible to control in fresh or minimally-processed seafood under aerobic or anaerobic storage conditions. This thesis considers strategies to control growth of this bacterium on seafood using both established and novel non-thermal technologies and seeks to elucidate physiological mechanisms underlying one of the approaches, namely high pressure processing. Chapter 1 reviews the microbiology of seafood including normal microbiota, spoilage processes, pathogen ecology and occurrence and non-thermal processes that are currently used or have the potential to be utilized by the seafood industry. It serves as reference material for the following chapters. Chapter 2 describes an empirical assessment of several preservatives proposed as antilisterial agents. In collaboration with a local Atlantic salmon smokehouse, three commercially available antimicrobial preparations were applied directly to salmon fillets prior to smoking with the intent to stop Listeria monocyto genes growth on vacuum packed cold smoked salmon (CSS). The challenge trial extended over 40 days at 4°C and 10°C. Microbial and sensorial analyses were conducted in parallel. Results showed that two of the three treatments evaluated presented listeriostactic activity. The remaining compound appeared not to penetrate in the salmon flesh and challenge the Listeria monocyto genes introduced to the inner flesh after slicing. From the sensorial point of view one of the successful Listeria monocyto genes growth inhibitors performed slightly better than the other but significantly better than the untreated CSS, making it a good candidate to control the growth of this pathogen in this commodity. A search for novel, cold-active, anti-listerial bacteriocins is the focus of Chapter 3. Specifically, 1600 Actinobacterial isolates from Antarctic or Sub-Antartcic regions were screened against five different Listeria monocyto genes strains for their capacity to produce cold active antimicrobials. Several promising isolates were identified and their active products partially characterized. The investigation demonstrated that Antarctic or Sub-Antarctic soils harbour potentially valuable antimicrobial producers with specific capacity to target single pathogen species and their potential to food safety and industry. Future bio-prospecting research for antimicrobials against pathogens of human concern should include species from other extreme environments as well. Chapter 4 and 5 describe studies concerning physiological responses of Listeria monocyto genes to high pressure processing (HPP). Chapter 4 explores whether the cell membrane is an important mediator of the effects of HPP and reports studies of changes in the fatty acid composition of the membrane in response to HPP. The results suggested that under pressure, irrespective of the growth phase, Listeria monocyto genes tries to adapt by changing the abundance of iso branched-chain fatty acid of its cell membrane. This fatty acid adaptive response is different from that caused by cold, pH and heat stresses. In Chapter 5 microarray technology is used to assess changes in gene expression under the same experimental conditions showing that HPP seems to invoke a cell maintenance state but strongly suppresses genes associated with catabolism and virulence. Chapter 6 synthesises the results of the work undertaken, attempts to determine the applicability of the novel non-thermal technologies (applied alone or as part of a multi hurdle approach) to increase the safety of minimally processed seafood products against listeriosis and identifies future research needs.

碩士
國立屏東科技大學
水產養殖系
92
This research discusses the acclimation responses and physiological change, focused on the energetics, of the giant seaperch, Lates calcarifer, under different thermal stress and remnant chlorine concentration environment. The tolerance and adaptive response under this dual adverse circumstance, becomes the basis of environmental impact evaluation. In gentle warming pressure, giant seaperch dies in the water temperature 42~42.4 ℃; In sublethal tolerance experiment, giant seaperch is really resistant to the hypochlorous acid pressure below the water temperature 34 ℃. High survival rate was obtained under chlorine concentration up to 2 mg/ l, but the rate obviously decline when the water temperature is 38 ℃. In blood biochemistry analysis, there are no significant difference of blood glucose change physiologically under water temperature 25~34 ℃. For 38 ℃ group, it is extremely obvious high in blood glucose concentration. The blood lactic acid quantity has rises under the different water temperature, also degree of the rise is becomes the relevance change scope with the temperature. Water temperature and chlorine residue, both contribute the stress for giant seaperch but in different mechanism. The water temperature has created a physiological reaction hyperglycemia, but the chlorine residue actually has the suppression effect on energy metabolism, also its suppression is positive proportional to the remnant chlorine concentration. Changes in blood lactic acid concentration appears is the early time of stress, also proportional to the intensity of stimuli, including thermal elevation and chlorine residue increasing. The concentration of blood lactic acid is suitable for being stress response index as its sensitivity to stressors. In muscle, difference and change of glucose and glycogen content did not show any significant varience within short time. But the lactic acid accumulation in muscle, reveal the physilogical stress caused by the existence of chlorine residue, which indicated energy supply by anaerobic metabolism while giant seaperch is in urgency or burst muscular motion. In liver, however, nearly contains no lactic acid and it is not feasible for monitoring the physiological response of stress reaction. Liver glycogen content demonstrated the chlorine residue suppression on energy metabolism, but under the identical chlorine concentration, the glycogen content change did not reflect the different thermal treatments, no statistic significance obtained. Consumption of energy for physiological regulation resulted in glucose concentration declined and immediately recovered in liver, explained the energy source comes from glycolysis or fatty acid oxidation but glycogenolysis, which changed the glucose content.

Lasers pose a safety hazards both to skin and particularly to something you value highly - your vision. The increasingly widespread use of IR wavelengths laser systems requires awareness with the potential hazards associated with the misuse of these valuable products. The principal goal of this research is to integrate experimental and theoretical descriptions of thermal response of skin and cornea to IR wavelength laser irradiation to yield a basis for the dosimetry of laser-tissue interaction. The threshold radiant exposures for various spot sizes and exposure durations were investigated on in vivo skin and cornea for 2.0 [mu]m laser irradiation. Similar study was also conducted on in vivo skin using 1.214 [mu]m laser and compared with 2.0 [mu]m results. This PhD study has, for the first time, linked temperature response, histopathology, and the more common "minimal visible lesion (MVL)" endpoint into what can be a meaningful comparison of rate process models for injury. Based on experimental data, a finite-element optical-thermal-damage model was developed. Histological damage was measured and modeled using sub-threshold, threshold, and super-threshold 2.0 [mu]m laser powers. The data provided experimental evidence of the correlation of sub-threshold histological change to visible threshold lesion for the irradiation condition of this study. Moreover, the computer model, supported by experimental validation, ensured that rate process models were used correctly in the prediction of "MVL" thresholds which were based upon a finite damage extent and not necessarily central surface layer damage. Thermal image method was employed to measure the absorption coefficient of in vivo skin at 2.0 [mu]m, at which wavelength scattering can be ignored. At laser wavelengths below 1.4 [mu]m where scattering cannot be ignored, an ameliorative method was explored to measure absorption and reduce scattering of in vivo tissue by combining pulse photothermal radiometry (PPTR) and diffuse reflectance (DR) measurements.

The focus of this dissertation is on bed bug thermal biology. How bed bugs react to heat exposure at the population, behavioral, and physiological levels was explored. The thermal tolerance of different bed bug populations and sublethal effects heat exposure were investigated. The temperatures that cause bed bugs to flee from their harborages was determined using a custom made arena. How bed bug physiology changes after heat exposure was determined using RT-qPCR. Finally, how conspecifics react to bed bugs that have been lethally exposed to heat was determined using still air bioassays.