Ingestion of cold (<10°C) compared to warm (>37°C) fluid has been suggested to attenuate heat storage levels during exercise. However, modulations in sweat output may yield differences in evaporative heat loss that are greater than differences in heat transfer with the ingested fluid. The purpose of the thesis was to evaluate thermoregulatory control and human heat balance, and compare thermometrically derived values of heat storage with those derived from partitional calorimetry following water ingestion of varying temperature during exercise. We found that water ingestion of 50°C compared to 1.5°C decreases heat storage in thermoneutral environments, and further exacerbates the error of thermometric heat storage estimations. Differences in heat storage were attributed exclusively to disproportionate reductions in whole-body and local sweat output and thus evaporative heat loss potential. Ingested fluid temperature only minimally altered skin blood flow and did not influence dry heat exchange with the ambient environment.

Studies performed on stallions have characterized detrimental effects on semen quality resulting from thermal stress by testicular insulation, but few have investigated the effects of exercise-induced increases in core body temperature on stallion semen parameters. To our knowledge, this is the first study that correlates subcutaneous scrotal temperature and stallion spermatozoa quality using a subdermal scrotal thermal sensory device. Stallions were assigned to a non-exercised (non-ex; control; n=4) or exercised (ex; n=4) group. A motorized equine exerciser was used to work stallions 30 min/d for 4 d/wk during a 12-wk period from July through October. Temperatures (subcutaneous scrotal, subcutaneous neck, rectal, and ambient) were recorded before exercise, immediately after exercise, and 60 and 120 min post-exercise. Humidity data were obtained later to determine THI. No deleterious effects were observed from implantation of thermal sensory devices. An interaction of treatment and time (P < 0.0001) was evident for rectal and neck temperatures. The relationship between scrotal and rectal temperatures was highest (rs =0.761), and other correlations existed between scrotal, neck, and ambient temperatures, as well. Mean rectal temperature in the ex group increased 1.9°C (P < 0.0001), while there was a slight increase in scrotal temperature of 0.8°C (P > 0.05) from 0 min to 22 min. Although an increase in core body temperature was successfully induced by exercise protocol, scrotal temperatures were not significantly affected, and no treatment effects were found in any of the semen parameters measured (P > 0.05). Therefore, no significant changes in fresh or cooled semen parameters resulted from exercise or increases in core body temperature resulting from exercise protocol used in this study. Results of this study indicate that thermal sensory devices are a safe and effective way to measure subcutaneous scrotal and neck temperatures. Although an increase in core body temperature was successfully induced by exercise protocol, scrotal temperatures were not significantly affected, indicating efficient thermoregulation of the testes by the scrotum. Since the testes experienced no significant thermal insult during the exercise protocol, no significant changes in fresh or cooled semen parameters were evident as a result of exercise or elevated core temperature.

Göttingen, Universität, Habilitation, 1998.

An animal’s ability to find thermal comfort can be can be limited within a zoo enclosure. This creates a need to design comfortable microclimates for the animal within their enclosure space. This is an exploratory study intended to investigate the relationships between an elephant’s movements throughout their space and the microclimatic conditions within its zoological enclosure. By outlining an understanding of microclimates and how they are affected by the landscape combined with knowledge of elephant behaviours it will be possible design or plan for microclimatic use within zoo enclosures. Observational data were collected from five Asian elephants (Elephas maximus). The movements of the elephants were monitored along with the use of microclimates within their enclosure. Thermal regulatory movements involving microclimatic use typically involved water and shade use, however evidence suggests that the animals were also avoiding terrestrial radiation from some of the gunite walls. It is important that animals are given the opportunity to find microclimates within the space to regulate their body temperature. Designing landscapes that incorporate microclimates within their habitats is crucial to the welfare and health of zoo elephants.

Colours influence numerous aspects of an animal’s ecology and the adaptive significance of colour variation has been intensively studied in diverse taxonomic groups. This study was motivated by the question: Why do garter snakes vary in colour? To answer this question, I focused on Western Terrestrial Garter Snakes, Thamnophis elegans, which exhibit geographic variation in colouration (dark morph vs. light morph), and two different species of garter snake that occur in the same geographic region but vary in colour –light T. elegans and the Common Garter Snake, T. sirtalis. My work provides an objective quantification and analysis of snake colour and evaluates the influence of colour variation on ecological processes such as thermoregulation, crypsis, and antipredator behaviour. I compared body temperatures (Tbs) with available thermal opportunities, both in wild snakes and in a field experiment, to determine how snakes with contrasting colours differ in thermoregulation and temperature-dependent behaviours. Gravid females of the light and dark colour morphs of T. elegans exhibited comparable thermoregulatory behaviour at high temperatures; however, dark T. elegans maintained elevated Tbs when available temperatures dropped. In the field, dark-coloured snakes were more likely to be moving when first detected when Tbs were high, but this trend was reversed in light T. elegans. I quantified crypsis of snakes, in terms of colour and brightness, by measuring the spectral reflectance of snakes and the surrounding habitat. These data were visually modeled from the perspective of potential snake predators and human researchers. Overall, snakes selected basking sites that maximized crypsis and both colour morphs of T. elegans were equally cryptic. There was evidence suggesting that T. sirtalis was more cryptic than light T. elegans to snake predators. I collected a series of behavioural measurements for snakes pre- and post-capture. Light T. elegans were more likely to be moving when originally detected in the field than dark snakes. Distance to cover and injuries were important factors in explaining the antipredator behaviour of snakes in the field. Snakes became generally faster with increasing Tbs, but differences attributable to colour morph were not straightforward. A higher proportion of T. elegans of both colour morphs exhibited some type of movement when exposed to a simulated predatory attack. Thamnophis sirtalis, on the other hand, hung limp and motionless in the air. The less cryptic light T. elegans had a higher probability of having an injury than T. sirtalis but injury patterns between the equally cryptic light and dark T. elegans differed by sex. The relationships between colour and these various traits were complex, but, taken together, they highlighted how thermal ecology, crypsis, and anti-predator behaviours were related to a snake’s visual appearance. These results therefore provide an ecological underpinning for future genetic studies to identify potential candidate genes that may be responsible for the control of colour pattern in garter snakes. / Graduate / 0329 / 0306 / 0472

Exercise and/or heat-induced dehydration is associated with decreases in plasma volume (hypovolemia) and increases in plasma osmolality (hyperosmolality), which are thought to stimulate peripheral baroreceptors and central osmoreceptors respectively. Independently, plasma hyperosmolality and baroreceptor unloading have been shown to attenuate sweating and cutaneous vasodilation during heat stress, and therefore, negatively impact body temperature regulation. However, to date little is known regarding the combined influence of plasma hyperosmolality and baroreceptor unloading on thermoefferent activity. Therefore, we evaluated the separate and combined effects of baroreceptor unloading (via lower body negative pressure, LBNP) and plasma hyperosmolality (via infusion of 3% NaCl saline) on heat loss responses of sweating and cutaneous vascular conductance (CVC) during progressive whole-body heating. We show that the combined nonthermal influences of plasma hyperosmolality and baroreceptor unloading additively delay the onset threshold for CVC, relative to their independent effects. In contrast, baroreceptor unloading has no influence on the sweating response regardless of osmotic state. These divergent roles of plasma hyperosmolality and the baroreflex on heat loss responses might serve to enhance blood pressure and body core temperature regulation during dehydration and heat stress.

Ingestion of cold (<10°C) compared to warm (>37°C) fluid has been suggested to attenuate heat storage levels during exercise. However, modulations in sweat output may yield differences in evaporative heat loss that are greater than differences in heat transfer with the ingested fluid. The purpose of the thesis was to evaluate thermoregulatory control and human heat balance, and compare thermometrically derived values of heat storage with those derived from partitional calorimetry following water ingestion of varying temperature during exercise. We found that water ingestion of 50°C compared to 1.5°C decreases heat storage in thermoneutral environments, and further exacerbates the error of thermometric heat storage estimations. Differences in heat storage were attributed exclusively to disproportionate reductions in whole-body and local sweat output and thus evaporative heat loss potential. Ingested fluid temperature only minimally altered skin blood flow and did not influence dry heat exchange with the ambient environment.

Group A Streptococcus (GAS) is responsible for mild and common infections like tonsillitis and pharyngitis, and more serious invasive disorders like necrotizing fasciitis and glomerulonephritis. The ability to invade tissues is closely linked to the virulence factors expressed by the bacterium. Hyaluronic acid capsule expression is variable among all the strains in S. pyogenes and confers the capacity to evade the immune response. In a previous study, it was found that capsule production in CovR mutants was temperature-regulated, showing a basal level of capsule production at 37℃ but increased production was observed at 25℃. Moreover, it was found that when CvfA, an endoribonuclease, is mutated, this thermoregulation is abolished. Since an antisense RNA was found spanning the entire capsule operon, another ribonuclease, RNaseIII which is involved in dsRNA digestion, was considered as a possible candidate to regulate the antisense and capsule transcripts. In this study, the objective is to find if and how the ribonucleases regulate the capsule transcript and antisense RNA. Data suggests that RNaseIII does not have a role in the regulation. On the other hand, CvfA showed a key role in regulating transcript levels. Furthermore, temperature appears to have some effect on its activity.

O trabalho, composto de quatro experimentos, teve como objetivo geral avaliar a tolerância ao calor em ovinos, sua relação com a coloração do pelame e a presença ou ausência de lã em ovelhas de raças lanadas e deslanadas. Os experimentos foram conduzidos no Instituto de Zootecnia, localizado em Nova Odessa, Estado de São Paulo (22º42\'S e 47º18\'W, 570m de altitude). Nos primeiros três experimentos, avaliaram-se 83 ovelhas, das raças Santa Inês (31), Morada Nova (15), Texel (14), Suffolk (11) e Ile de France (12). O índice de tolerância ao calor (ITC) foi calculado pela fórmula 10 - (TR2 - TR1), através das temperaturas retais registradas às 13h (TR1), após duas horas em descanso na sombra, e às 15h, após uma hora de exposição à radiação solar direta e uma hora de descanso à sombra (TR2). No quarto experimento, 90 ovelhas, 18 de cada raça, foram avaliadas quanto à temperatura retal (TR) e freqüência respiratória (FR) às 8h, 13h (após duas horas em descanso à sombra), 14h (após uma hora de exposição ao sol), e depois a cada 15 minutos, na sombra, até às 15h, originando quatro TR2 para cálculo dos índices. Verificou-se que não houve diferença na tolerância ao calor entre animais da raça Santa Inês de pelagem clara e escura. A raça Texel (lanada) teve menor variação de temperatura entre os dois horários, e obteve melhor índice de tolerância ao calor (P<0,05) do que a raça deslanada Morada Nova. Ovelhas das raças Suffolk e Ile de France tiveram altos índices de tolerância ao calor, independente do fato de estarem ou não tosquiadas. No experimento 4, ovelhas da raça Santa Inês tiveram TR inferiores (P<0,05) à TR de algumas raças lanadas, às 13h, 14h, 14h30min e 14h45min. Em todas as raças, não houve diferença (P>0,05) entre as TR medidas às 8h e 13h, assim como não foram encontradas diferenças (P>0,05) entre elas quanto à TR da manhã e aos 60 min após o estresse (15h). As ovelhas deslanadas tiveram FR inferiores (P<0,05) às lanadas. Não houve diferença (P>0,05) entre o ITC calculado com base na TR2 aos 45 e 60 min pósestresse. Concluiu-se que o tempo de registro da TR2 para a espécie ovina pode ser antecipado de 60 para 45 minutos após o estresse, e que as ovelhas avaliadas estão adaptadas ao clima do Estado de São Paulo. / This study consisted of 4 experiments and had as main goal evaluate the heat tolerance in ewes, and its relation to hair color and presence or absence of wool in wool and hair breeds. The experiments were conducted at the Instituto de Zootecnia, located in Nova Odessa city, São Paulo State, Brazil (22º42\'S e 47º18\'W, 570m altitude). Three experiments evaluated 83 ewes of the following breeds: (31) Santa Inês; (15) Morada Nova; (14) Texel; (11) Suffolk and (12) Ile de France. The heat tolerance index is calculated on the formula 10 - (RT2 - RT1) through data on rectal temperatures (RT) as follows: RT1 at 13:00h, after 2 hours of rest in the shade and RT2 at 15:00h, after na hour of sun exposure and one hour of rest in the shade. The fourth experiment examined a 90 ewe flock, consisted of 18 ewes of each breed, which were evaluated for rectal temperature (RT) and respiratory frequency (RF) as follows: 8:00h, 13:00h (after 2 hour shade rest); 14:00h (after one hour sun exposure) and in the shade, every 15 minutes till the hour; which provided four RT2 for the index. There was no heat tolerance difference between light or dark hair colored Santa Ines. Texel ewes (wool breed) presented the lowest variation of temperature between the two timeframes and had best heat tolerance index (P<0,05) than the hair breed Morada Nova. Suffolk and Ile de France ewes had high heat tolerance index values, irrespective of having been sheared or not. In the fourth experiment, Santa Inês ewes presented lower RT (P<0,05), than some wool breeds at 13:00h, 14:00h, 14:30h and 14:45h. In all breeds, there was no difference (P>0,05) between the RT values taken at 8h and 13h. In addition, no significant differences (P>0,05) were found among the breeds between the RT values recorded in the morning and the RT taken 60min after heat stress (15h). The hair breeds presented lower RF (P<0,05) than the wool breeds. No difference was found amongst the heat tolerance indexes based on RT2 at 45 and 60min after stress. It was concluded that the registering time of RT2 for sheep can be advanced from 60 to 45 min after stress, and that the ewes in the experiment are all adapted to São Paulo State\'s weather.

Exercise and/or heat-induced dehydration is associated with decreases in plasma volume (hypovolemia) and increases in plasma osmolality (hyperosmolality), which are thought to stimulate peripheral baroreceptors and central osmoreceptors respectively. Independently, plasma hyperosmolality and baroreceptor unloading have been shown to attenuate sweating and cutaneous vasodilation during heat stress, and therefore, negatively impact body temperature regulation. However, to date little is known regarding the combined influence of plasma hyperosmolality and baroreceptor unloading on thermoefferent activity. Therefore, we evaluated the separate and combined effects of baroreceptor unloading (via lower body negative pressure, LBNP) and plasma hyperosmolality (via infusion of 3% NaCl saline) on heat loss responses of sweating and cutaneous vascular conductance (CVC) during progressive whole-body heating. We show that the combined nonthermal influences of plasma hyperosmolality and baroreceptor unloading additively delay the onset threshold for CVC, relative to their independent effects. In contrast, baroreceptor unloading has no influence on the sweating response regardless of osmotic state. These divergent roles of plasma hyperosmolality and the baroreflex on heat loss responses might serve to enhance blood pressure and body core temperature regulation during dehydration and heat stress.