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3.
PLoS One ; 15(5): e0232400, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32384084

RESUMO

Metabolic parameters ranging from circulating nutrient levels and substrate utilization to energy expenditure and thermogenesis are temporally modulated by the circadian timing system. During critical embryonic developmental periods, maternal over-nutrition could alter key elements in different tissues associated with the generation of circadian rhythmicity, compromising normal rhythmicity development. To address this issue, we determine whether maternal over-nutrition leads to alterations in the development of circadian rhythmicity at physiological and behavioral levels in the offspring. For this, female rabbits were fed a standard diet (SD) or high-fat and carbohydrate diet (HFCD) before mating and during gestation. Core body temperature and gross locomotor activity were continuously recorded in newborn rabbits, daily measurements of body weight and the amount of milk ingested was carried out. At the end of lactation, tissue samples, including brown adipose tissue (BAT) and white adipose tissue (WAT), were obtained for determining the expression of uncoupling protein-1 (UCP1) and cell death-inducing DNA fragmentation factor-like effector A (CIDEA) genes. HFCD pups exhibited conspicuous differences in the development of the daily rhythm of temperature and locomotor activity compared to the SD pups, including a significant increase in the daily mean core temperature, changes in the time when temperature or activity remains above the average, shifts in the acrophase, decrease in the duration and intensity of the anticipatory rise previous to nursing, and changes in frequency of the rhythms. HFCD pups exhibited a significant increase in BAT thermogenesis markers, and a decrease of these markers in WAT, indicating more heat generation by brown adipocytes and alterations in the browning process. These results indicate that maternal over-nutrition alters offspring homeostatic and chronostatic regulation at the physiological and behavioral levels. Further studies are needed to determine whether these alterations are associated with the changes in the organization of the circadian system of the progeny.


Assuntos
Regulação da Temperatura Corporal/fisiologia , Ritmo Circadiano/fisiologia , Lactação/fisiologia , Locomoção/fisiologia , Tecido Adiposo Marrom/fisiopatologia , Tecido Adiposo Branco/fisiopatologia , Animais , Proteínas Reguladoras de Apoptose/genética , Regulação da Temperatura Corporal/genética , Ritmo Circadiano/genética , Modelos Animais de Doenças , Feminino , Expressão Gênica , Lactação/genética , Locomoção/genética , Fenômenos Fisiológicos da Nutrição Materna , Hipernutrição/complicações , Hipernutrição/genética , Hipernutrição/fisiopatologia , Gravidez , Complicações na Gravidez/genética , Complicações na Gravidez/fisiopatologia , Coelhos , Proteína Desacopladora 1/genética
4.
Proc Natl Acad Sci U S A ; 117(16): 8958-8965, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32253313

RESUMO

Olfaction and thermoregulation are key functions for mammals. The former is critical to feeding, mating, and predator avoidance behaviors, while the latter is essential for homeothermy. Aquatic and amphibious mammals face olfactory and thermoregulatory challenges not generally encountered by terrestrial species. In mammals, the nasal cavity houses a bony system supporting soft tissues and sensory organs implicated in either olfactory or thermoregulatory functions. It is hypothesized that to cope with aquatic environments, amphibious mammals have expanded their thermoregulatory capacity at the expense of their olfactory system. We investigated the evolutionary history of this potential trade-off using a comparative dataset of three-dimensional (3D) CT scans of 189 skulls, capturing 17 independent transitions from a strictly terrestrial to an amphibious lifestyle across small mammals (Afrosoricida, Eulipotyphla, and Rodentia). We identified rapid and repeated loss of olfactory capacities synchronously associated with gains in thermoregulatory capacity in amphibious taxa sampled from across mammalian phylogenetic diversity. Evolutionary models further reveal that these convergences result from faster rates of turbinal bone evolution and release of selective constraints on the thermoregulatory-olfaction trade-off in amphibious species. Lastly, we demonstrated that traits related to vital functions evolved faster to the optimum compared to traits that are not related to vital functions.


Assuntos
Evolução Biológica , Regulação da Temperatura Corporal/fisiologia , Mamíferos/fisiologia , Cavidade Nasal/fisiologia , Olfato/fisiologia , Animais , Imageamento Tridimensional , Cavidade Nasal/anatomia & histologia , Cavidade Nasal/diagnóstico por imagem , Filogenia , Natação/fisiologia , Tomografia Computadorizada por Raios X , Conchas Nasais/anatomia & histologia , Conchas Nasais/diagnóstico por imagem , Conchas Nasais/fisiologia
5.
Am J Physiol Regul Integr Comp Physiol ; 318(5): R950-R960, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32233779

RESUMO

Military and civilian emergency situations often involve prolonged exposures to warm and very humid environments. We tested the hypothesis that increases in core temperature and body fluid losses during prolonged exposure to warm and very humid environments are dependent on dry bulb temperature. On three occasions, 15 healthy males (23 ± 3 yr) sat in 32.1 ± 0.1°C, 33.1 ± 0.2°C, or 35.0 ± 0.1°C and 95 ± 2% relative humidity normobaric environments for 8 h. Core temperature (telemetry pill) and percent change in body weight, an index of changes in total body water occurring secondary to sweat loss, were measured every hour. Linear regression models were fit to core temperature (over the final 4 h) and percent changes in body weight (over the entire 8 h) for each subject. These equations were used to predict core temperature and percent changes in body weight for up to 24 h. At the end of the 8-h exposure, core temperature was higher in 35°C (38.2 ± 0.4°C, P < 0.01) compared with 32°C (37.2 ± 0.2°C) and 33°C (37.5 ± 0.2°C). At this time, percent changes in body weight were greater in 35°C (-1.9 ± 0.5%) compared with 32°C (-1.4 ± 0.3%, P < 0.01) but not 33°C (-1.6 ± 0.6%, P = 0.17). At 24 h, predicted core temperature was higher in 35°C (39.2 ± 1.4°C, P < 0.01) compared with 32°C (37.6 ± 0.9°C) and 33°C (37.5 ± 0.9°C), and predicted percent changes in body weight were greater in 35°C (-6.1 ± 2.4%) compared with 32°C (-4.6 ± 1.5%, P = 0.04) but not 33°C (-5.3 ± 2.0%, P = 0.43). Prolonged exposure to 35°C, but not 32°C or 33°C, dry bulb temperatures and high humidity is uncompensable heat stress, which exacerbates body fluid losses.


Assuntos
Regulação da Temperatura Corporal , Exposição Ambiental , Transtornos de Estresse por Calor/fisiopatologia , Temperatura Alta , Umidade , Militares , Medicina Submarina , Adulto , Deslocamentos de Líquidos Corporais , Transtornos de Estresse por Calor/etiologia , Humanos , Masculino , Modelos Biológicos , Estado de Hidratação do Organismo , Sudorese , Fatores de Tempo , Equilíbrio Hidroeletrolítico , Perda de Peso , Adulto Jovem
6.
Sci Total Environ ; 718: 137380, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32325625

RESUMO

Impacts of large-scale oil spills on avian species are far-reaching. While media attention often focuses on lethal impacts, sub-lethal effects and the impacts of rehabilitation receive less attention. The objective of our study was to characterize effects of moderate external oiling and subsequent rehabilitation on feather structure and thermoregulation in gulls. We captured 30 wild ring-billed gulls (Larus delawarensis) and randomly assigned each individual to an experimental group: 1) controls, 2) rehabilitated birds (externally oiled, rehabilitated by washing), or 3) oiled birds (externally oiled, not rehabilitated). We externally oiled birds with weathered MC252 Deepwater Horizon oil (water for controls) and collected feathers and thermography imagery (FLIR) approximately weekly for four weeks to investigate feather structure (quantified using a barbule clumping index) and thermoregulatory ability (characterized by internal body temperature and external surface temperature). Post-oiling feather clumping was significantly higher in oiled and rehabilitated birds compared to controls, but steadily declined over time in both groups. However, feather microstructure in rehabilitated birds was indistinguishable from controls within three weeks of washing whereas the feathers of oiled birds were still significantly clumped a month post oiling. Internal body temperatures didn't differ in any of the groups, suggesting birds maintain thermoregulatory homeostasis in spite of moderate external oiling. External temperatures for rehabilitated birds didn't differ from controls within a week of rehabilitation. Overall, rehabilitation procedures were effective and washed birds were in better condition compared to non-rehabilitated, oiled birds. This study provides evidence that the benefits of rehabilitation for moderately oiled birds likely outweigh the costs with regard to feather structure and thermoregulation. While feather preening and time were insufficient to reestablish baseline fine scale feather structure in moderately oiled birds, the significant clumping reduction over time may indicate that rehabilitation of lightly oiled birds may not be necessary and deserves further study.


Assuntos
Charadriiformes , Petróleo , Animais , Regulação da Temperatura Corporal , Plumas , Poluição por Petróleo
7.
Oecologia ; 193(1): 225-235, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32296953

RESUMO

During hot weather, terrestrial animals often seek shaded thermal refugia. However, this can result in missed foraging opportunities, loss of body condition and impaired parental care. We investigated whether such costs could compromise breeding success in a widespread southern African bird: the Southern Yellow-Billed Hornbill Tockus leucomelas. We predicted that hornbills might be especially vulnerable to temperature-dependant reductions in parents' foraging capacity due to extreme asymmetry in sex-specific roles during breeding: females are confined within the nest cavity for most of the nesting period and the burden of provisioning falls solely on the male during this time. We followed 50 hornbill nesting attempts in the Kalahari Desert between 2012 and 2015, collecting data on provisioning rates, adult and nestling body mass, fledging success and size of fledglings. Mean daily maximum air temperatures (Tmax) during nesting attempts ranged from 33.2 to 39.1 °C. The likelihood of successful fledging fell below 50% at mean Tmax > 35.1 °C; a threshold now regularly exceeded at our study site due to recent climate warming. Additionally, offspring fledging following the hottest nesting attempts were > 50% lighter than those fledging following the coolest. Sublethal costs of keeping cool including loss of body condition, production of poor-quality offspring and breeding failure are likely to become issues of serious conservation concern as climate change progresses; even for currently widespread species. Missed-opportunity costs associated with behavioral thermoregulation and direct sublethal costs of temperature exposure should not be overlooked as a potential threat to populations, especially in environments that are already hot.


Assuntos
Aves , Temperatura Alta , Animais , Regulação da Temperatura Corporal , Cruzamento , Feminino , Masculino , Comportamento de Nidação , Temperatura
8.
Curr Sports Med Rep ; 19(4): 142-145, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32282459

RESUMO

Exercising in hot, humid temperatures increases the risk for heat-related illnesses, ranging from mild heat edema to severe heat stroke. With increasing globalization in the world of sports, athletes are sometimes expected to compete in unforgiving conditions that expose them to these risks. In an effort to improve exercise capacity and reduce the risk of serious heat injury, many athletes are recommended to undergo heat acclimatization program prior to competing in climates with elevated average temperature. This article will look at current recommendations as well as studies on differing techniques for acclimatization and acclimation, with hopes to provide guidance for the modern-day clinician and athletes.


Assuntos
Aclimatação , Regulação da Temperatura Corporal , Exercício Físico , Temperatura Alta , Atletas , Humanos , Esportes
9.
Pediatrics ; 145(4)2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32193210

RESUMO

OBJECTIVES: Reduce postoperative hypothermia by up to 50% over a 12-month period in children's hospital NICUs and identify specific clinical practices that impact success. METHODS: Literature review, expert opinion, and benchmarking were used to develop clinical practice recommendations for maintaining perioperative euthermia that included the following: established euthermia before transport to the operating room (OR), standardized practice for maintaining euthermia on transport to and from the OR, and standardized practice to prevent intraoperative heat loss. Process measures were focused on maintaining euthermia during these time points. The outcome measure was the proportion of patients with postoperative hypothermia (temperature ≤36°C within 30 minutes of a return to the NICU or at the completion of a procedure in the NICU). Balancing measures were the proportion of patients with postoperative temperature >38°C or the presence of thermal burns. Multivariable logistic regression was used to identify key practices that improved outcome. RESULTS: Postoperative hypothermia decreased by 48%, from a baseline of 20.3% (January 2011 to September 2013) to 10.5% by June 2015. Strategies associated with decreased hypothermia include >90% compliance with patient euthermia (36.1-37.9°C) at times of OR arrival (odds ratio: 0.58; 95% confidence interval [CI]: 0.43-0.79; P < .001) and OR departure (odds ratio: 0.0.73; 95% CI: 0.56-0.95; P = .017) and prewarming the OR ambient temperature to >74°F (odds ratio: 0.78; 95% CI: 0.62-0.999; P = .05). Hyperthermia increased from a baseline of 1.1% to 2.2% during the project. No thermal burns were reported. CONCLUSIONS: Reducing postoperative hypothermia is possible. Key practices include prewarming the OR and compliance with strategies to maintain euthermia at select time points throughout the perioperative period.


Assuntos
Hipotermia/prevenção & controle , Assistência Perioperatória/métodos , Complicações Pós-Operatórias/prevenção & controle , Benchmarking , Temperatura Corporal/fisiologia , Regulação da Temperatura Corporal/fisiologia , Queimaduras/epidemiologia , Humanos , Hipotermia/epidemiologia , Lactente , Unidades de Terapia Intensiva Neonatal , Modelos Logísticos , Razão de Chances , Salas Cirúrgicas , Avaliação de Resultados em Cuidados de Saúde , Período Perioperatório , Complicações Pós-Operatórias/epidemiologia , Desenvolvimento de Programas , Fatores de Tempo , Transporte de Pacientes
10.
Int J Biometeorol ; 64(7): 1221-1231, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32193595

RESUMO

Seasonal variations in day length and light intensity can affect the circadian rhythm as well as some characteristics of temperature regulation. We investigated characteristics of autonomic (ATR), behavioural (BTR) and nocturnal (NTR) temperature regulation during spring and autumn. Eleven participants underwent experiments in both seasons. To assess ATR, participants performed a 30-min bout of submaximal upright exercise on a cycle ergometer, followed by 100 min of water immersion (28 °C). Thresholds for the onset of shivering and sweating and vasomotor response were measured. BTR was assessed using a water-perfused suit, with participants regulating the water-perfused suit temperature (Twps) within a range, considered as thermally comfortable. The Twps changed in a saw-tooth manner from 10 to 50 °C; by depressing a switch, the direction of the Twps changed, and this limit defined the thermal comfort zone (TCZ) for each participant. A 24-h proximal (calf)-distal (toe) skin temperature gradient (∆Tc-t) was measured to assess NTR. Initiation of vasomotor tone, shivering and sweating was similar between trials. Width of the TCZ was 8.1 °C in spring and 8.6 °C in autumn (p = 0.1), with similar upper and lower regulated temperatures. ∆Tc-t exhibited a typical circadian rhythm with no difference between seasons. Minor changes in skin temperature and oxygen consumption (p Ë‚ 0.05) between the seasons may indicate a degree of seasonal adaptation over the course of winter and summer, which persisted in spring and autumn. Other factors, such as country, race, sex and age could however modify the outcome of the study.


Assuntos
Regulação da Temperatura Corporal , Temperatura Cutânea , Humanos , Estações do Ano , Sudorese , Temperatura
11.
PLoS Med ; 17(3): e1003040, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32134952

RESUMO

BACKGROUND: Electrocardiographic QT interval prolongation is the most widely used risk marker for ventricular arrhythmia potential and thus an important component of drug cardiotoxicity assessments. Several antimalarial medicines are associated with QT interval prolongation. However, interpretation of electrocardiographic changes is confounded by the coincidence of peak antimalarial drug concentrations with recovery from malaria. We therefore reviewed all available data to characterise the effects of malaria disease and demographic factors on the QT interval in order to improve assessment of electrocardiographic changes in the treatment and prevention of malaria. METHODS AND FINDINGS: We conducted a systematic review and meta-analysis of individual patient data. We searched clinical bibliographic databases (last on August 21, 2017) for studies of the quinoline and structurally related antimalarials for malaria-related indications in human participants in which electrocardiograms were systematically recorded. Unpublished studies were identified by the World Health Organization (WHO) Evidence Review Group (ERG) on the Cardiotoxicity of Antimalarials. Risk of bias was assessed using the Pharmacoepidemiological Research on Outcomes of Therapeutics by a European Consortium (PROTECT) checklist for adverse drug events. Bayesian hierarchical multivariable regression with generalised additive models was used to investigate the effects of malaria and demographic factors on the pretreatment QT interval. The meta-analysis included 10,452 individuals (9,778 malaria patients, including 343 with severe disease, and 674 healthy participants) from 43 studies. 7,170 (68.6%) had fever (body temperature ≥ 37.5°C), and none developed ventricular arrhythmia after antimalarial treatment. Compared to healthy participants, patients with uncomplicated falciparum malaria had shorter QT intervals (-61.77 milliseconds; 95% credible interval [CI]: -80.71 to -42.83) and increased sensitivity of the QT interval to heart rate changes. These effects were greater in severe malaria (-110.89 milliseconds; 95% CI: -140.38 to -81.25). Body temperature was associated independently with clinically significant QT shortening of 2.80 milliseconds (95% CI: -3.17 to -2.42) per 1°C increase. Study limitations include that it was not possible to assess the effect of other factors that may affect the QT interval but are not consistently collected in malaria clinical trials. CONCLUSIONS: Adjustment for malaria and fever-recovery-related QT lengthening is necessary to avoid misattributing malaria-disease-related QT changes to antimalarial drug effects. This would improve risk assessments of antimalarial-related cardiotoxicity in clinical research and practice. Similar adjustments may be indicated for other febrile illnesses for which QT-interval-prolonging medications are important therapeutic options.


Assuntos
Arritmias Cardíacas/fisiopatologia , Eletrocardiografia , Sistema de Condução Cardíaco/fisiopatologia , Frequência Cardíaca , Malária/fisiopatologia , Potenciais de Ação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antimaláricos/efeitos adversos , Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/diagnóstico por imagem , Arritmias Cardíacas/parasitologia , Regulação da Temperatura Corporal , Cardiotoxicidade , Criança , Pré-Escolar , Feminino , Sistema de Condução Cardíaco/efeitos dos fármacos , Sistema de Condução Cardíaco/parasitologia , Frequência Cardíaca/efeitos dos fármacos , Humanos , Lactente , Malária/diagnóstico , Malária/tratamento farmacológico , Malária/parasitologia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Medição de Risco , Fatores de Risco , Índice de Gravidade de Doença , Resultado do Tratamento , Adulto Jovem
12.
Oecologia ; 192(4): 919-928, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32166391

RESUMO

Edible dormice (Glis glis) can remain entirely solitary but frequently share sleeping sites with conspecifics in groups of up to 16 adults and yearlings. Here, we analysed grouping behaviour of 4564 marked individuals, captured in a 13-year study in nest boxes in a deciduous forest. We aimed to clarify (i) whether social thermoregulation is the primary cause for group formation and (ii) which factors affect group size and composition. Dormice temporarily formed both mixed and single-sex groups in response to acute cold ambient temperatures, especially those individuals with small body mass. Thus, thermoregulatory huddling appears to be the driving force for group formation in this species. Huddling was avoided-except for conditions of severe cold load-in years of full mast seeding, which is associated with reproduction and high foraging activity. Almost all females remained solitary during reproduction and lactation. Hence, entire populations of dormice switched between predominantly solitary lives in reproductive years to social behaviour in non-reproductive years. Non-social behaviour pointed to costs of huddling in terms of competition for local food resources even when food is generally abundant. The impact of competition was mitigated by a sex ratio that was biased towards males, which avoids sharing of food resources with related females that have extremely high energy demands during lactation. Importantly, dormice preferentially huddled in male-biased groups with litter mates from previous years. The fraction of related individuals increased with group size. Hence, group composition partly offsets the costs of shared food resources via indirect fitness benefits.


Assuntos
Myoxidae , Animais , Regulação da Temperatura Corporal , Feminino , Cavalos , Masculino , Reprodução , Comportamento Social
13.
Mol Cell ; 78(1): 57-69.e4, 2020 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-32059760

RESUMO

Homeothermic organisms maintain their core body temperature in a narrow, tightly controlled range. Whether and how subtle circadian oscillations or disease-associated changes in core body temperature are sensed and integrated in gene expression programs remain elusive. Furthermore, a thermo-sensor capable of sensing the small temperature differentials leading to temperature-dependent sex determination (TSD) in poikilothermic reptiles has not been identified. Here, we show that the activity of CDC-like kinases (CLKs) is highly responsive to physiological temperature changes, which is conferred by structural rearrangements within the kinase activation segment. Lower body temperature activates CLKs resulting in strongly increased phosphorylation of SR proteins in vitro and in vivo. This globally controls temperature-dependent alternative splicing and gene expression, with wide implications in circadian, tissue-specific, and disease-associated settings. This temperature sensor is conserved across evolution and adapted to growth temperatures of diverse poikilotherms. The dynamic temperature range of reptilian CLK homologs suggests a role in TSD.


Assuntos
Processamento Alternativo , Regulação da Temperatura Corporal/genética , Expressão Gênica , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Répteis/genética , Animais , Evolução Biológica , Células HEK293 , Humanos , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/fisiologia , Proteínas Tirosina Quinases/química , Proteínas Tirosina Quinases/fisiologia , Répteis/metabolismo , Fatores de Processamento de Serina-Arginina/metabolismo
14.
Int J Sports Physiol Perform ; 15(5): 639-647, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32023545

RESUMO

PURPOSE: To examine the effects of daily cold- and hot-water recovery on training load (TL) during 5 days of heat-based training. METHODS: Eight men completed 5 days of cycle training for 60 minutes (50% peak power output) in 4 different conditions in a block counter-balanced-order design. Three conditions were completed in the heat (35°C) and 1 in a thermoneutral environment (24°C; CON). Each day after cycling, participants completed 20 minutes of seated rest (CON and heat training [HT]) or cold- (14°C; HTCWI) or hot-water (39°C; HTHWI) immersion. Heart rate, rectal temperature, and rating of perceived exertion (RPE) were collected during cycling. Session-RPE was collected 10 minutes after recovery for the determination of session-RPE TL. Data were analyzed using hierarchical regression in a Bayesian framework; Cohen d was calculated, and for session-RPE TL, the probability that d > 0.5 was also computed. RESULTS: There was evidence that session-RPE TL was increased in HTCWI (d = 2.90) and HTHWI (d = 2.38) compared with HT. The probabilities that d > 0.5 were .99 and .96, respectively. The higher session-RPE TL observed in HTCWI coincided with a greater cardiovascular (d = 2.29) and thermoregulatory (d = 2.68) response during cycling than in HT. This result was not observed for HTHWI. CONCLUSION: These findings suggest that cold-water recovery may negatively affect TL during 5 days of heat-based training, hot-water recovery could increase session-RPE TL, and the session-RPE method can detect environmental temperature-mediated increases in TL in the context of this study.


Assuntos
Ciclismo/fisiologia , Temperatura Baixa , Temperatura Alta , Imersão , Condicionamento Físico Humano/métodos , Adulto , Teorema de Bayes , Regulação da Temperatura Corporal , Teste de Esforço , Frequência Cardíaca/fisiologia , Humanos , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia , Água , Adulto Jovem
15.
BMC Evol Biol ; 20(1): 28, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054457

RESUMO

BACKGROUND: Temperature exerts a strong influence on protein evolution: species living in thermally distinct environments often exhibit adaptive differences in protein structure and function. However, previous research on protein temperature adaptation has focused on small numbers of proteins and on proteins adapted to extreme temperatures. Consequently, less is known about the types and quantity of evolutionary change that occurs to proteins when organisms adapt to small shifts in environmental temperature. In this study, these uncertainties were addressed by developing software that enabled comparison of structural changes associated with temperature adaptation (hydrogen bonding, salt bridge formation, and amino acid use) among large numbers of proteins from warm- and cold-adapted species of marine mussels, Mytilus galloprovincialis and Mytilus trossulus, respectively. RESULTS: Small differences in habitat temperature that characterize the evolutionary history of Mytilus mussels were sufficient to cause protein structural changes consistent with temperature adaptation. Hydrogen bonds and salt bridges that increase stability and protect against heat-induced denaturation were more abundant in proteins from warm-adapted M. galloprovincialis compared with proteins from cold-adapted M. trossulus. These structural changes were related to deviations in the use of polar and charged amino acids that facilitate formation of hydrogen bonds and salt bridges within proteins, respectively. Enzymes, in particular those within antioxidant and cell death pathways, were over-represented among proteins with the most hydrogen bonds and salt bridges in warm-adapted M. galloprovincialis. Unlike extremophile proteins, temperature adaptation in Mytilus proteins did not involve substantial changes in the number of hydrophobic or large volume amino acids, nor in the content of glycine or proline. CONCLUSIONS: Small shifts in organism temperature tolerance, such as that needed to cope with climate warming, may result from structural and functional changes to a small percentage of the proteome. Proteins in which function is dependent on large conformational change, notably enzymes, may be particularly sensitive to temperature perturbation and represent foci for natural selection. Protein temperature adaptation can occur through different types and frequencies of structural change, and adaptive mechanisms used to cope with small shifts in habitat temperature appear different from mechanisms used to retain protein function at temperature extremes.


Assuntos
Aclimatação , Mytilus/metabolismo , Proteínas/química , Proteínas/metabolismo , Temperatura , Aclimatação/genética , Adaptação Fisiológica/fisiologia , Sequência de Aminoácidos , Animais , Regulação da Temperatura Corporal/fisiologia , Ensaios de Triagem em Larga Escala/veterinária , Temperatura Alta , Ligação de Hidrogênio , Modelos Moleculares , Conformação Proteica , Processamento de Proteína Pós-Traducional/fisiologia , Proteoma/química , Proteoma/metabolismo , Relação Estrutura-Atividade
16.
J Anim Sci ; 98(3)2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32020198

RESUMO

Feed consumption increases body temperature and may delay a return to euthermia and exacerbate intestinal injury following acute hyperthermia recovery in pigs. Therefore, the study objective was to evaluate the effects of feed removal on body temperature and intestinal morphology in pigs exposed to acute hyperthermia and then rapidly cooled. Twenty-four gilts (78.53 ± 5.46 kg) were exposed to thermoneutral (TN; n = 12 pigs; 21.21 ± 0.31 °C; 61.88 ± 6.93% RH) conditions for 6 h, or heat stress (HS; 38.51 ± 0.60 °C; 36.38 ± 3.40% RH) conditions for 3 h followed by a 3-h recovery period of rapid cooling (HSC;n = 12 pigs; TN conditions and cold water dousing). Within each recovery treatment, one-half of the pigs were provided feed ad libitum (AF; n = 6 pigs per recovery treatment) and one-half of the pigs were not provided feed (NF; n = 6 pigs per recovery treatment). Gastrointestinal (TGI), vaginal (TV), and skin (TSK) temperatures and respiration rate (RR) were recorded every 15 min. Pigs were video-recorded to assess feeding and drinking attempts. Immediately following the 6-h thermal stress period, pigs were euthanized, and intestinal samples were collected to assess morphology. During the HS period, Tv, TGI, TSK, and RR were increased (P < 0.01; 1.63, 2.05, 8.32 °C, and 88 breaths per min, respectively) in HSC vs. TN pigs, regardless of feeding treatment. Gastrointestinal temperature was greater (P = 0.03; 0.97 °C) in HSC + AF vs. HSC + NF pigs from 45 to 180 min of the recovery period. During the recovery period, feeding attempts were greater (P = 0.02; 195.38%) in AF vs. NF pigs. No drinking attempt differences were detected with any comparison (P > 0.05). A decrease (P < 0.01) in jejunum and ileum villus height (24.72% and 26.11%, respectively) and villus height-to-crypt depth ratio (24.03% and 25.29%, respectively) was observed in HSC vs. TN pigs, regardless of feeding treatment. Ileum goblet cells were reduced (P = 0.01; 37.87%) in HSC vs. TN pigs, regardless of feeding treatment. In summary, TGI decreased more rapidly following acute hyperthermia when the feed was removed, and this may have implications toward using feed removal as a strategy to promote acute hyperthermia recovery in pigs.


Assuntos
Ração Animal/efeitos adversos , Regulação da Temperatura Corporal , Ingestão de Alimentos , Febre/veterinária , Suínos/fisiologia , Animais , Temperatura Corporal , Temperatura Baixa , Feminino , Trato Gastrointestinal/citologia , Resposta ao Choque Térmico , Temperatura Alta , Mucosa Intestinal/citologia , Intestinos/citologia , Taxa Respiratória
18.
Int J Biometeorol ; 64(3): 485-499, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32016640

RESUMO

Evaporative cooling is the critical heat dissipation mechanism for working individuals wearing thermal protective clothing in hot environments. However, until now, there is no knowledge on garment size design for evaporative cooling optimization, especially when the human body is in movements. In this study, to understand the dynamic effect of garment size on evaporative cooling, we performed experiments on a sweating thermal manikin with seven garment sizes and three walking speeds. The evaporative cooling of global and local manikin body with this wide range garment sizes was present. Results demonstrated that the effect of garment size on evaporative cooling depended on the walking speed. At lower walking speeds, the global evaporative cooling tended to decrease with greater garment size, while at higher walking speeds, the global evaporative cooling tended to increase with greater garment size. Similarly, according to effects of garment size on local evaporative cooling, body segments could be divided into three categories for evaporative cooling optimization. Further, we analyzed factors which influenced the positive effect of walking speed on the evaporative cooling. Results showed that, for most cases, the increase of evaporative cooling caused by walking showed positive linear relationship with the garment size. Further increase of walking speed led to a greater increase rate of evaporative heat loss for body segments with the small air gap. This study provides insights into clothing local characteristics of evaporative cooling with different garment sizes under dynamic conditions and may help clothing design to optimize the evaporative cooling of working individuals in hot environments.


Assuntos
Manequins , Caminhada , Regulação da Temperatura Corporal , Temperatura Alta , Humanos , Roupa de Proteção , Sudorese
19.
Animal ; 14(S1): s124-s132, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32024577

RESUMO

Ruminants living in seasonal environments face a two-fold challenge during winter. The energetic cost of maintaining a high body temperature is higher at lower ambient temperatures, and this is compounded by poor availability and quality of feed. Wild ruminants acclimatize to this energetic challenge by hypothermia, that is, reduced endogenous heat production and abandoning the maintenance of a high body temperature, particularly in peripheral body parts. Further but lesser contributions to lower energy expenditure during winter are reduced foraging activity; lower heat increment of feeding; and reduced maintenance cost of size-reduced organs. Altogether, metabolic rate, estimated by the continuous measurement of heart rate, during winter is downregulated to more than half of the summer level, as is voluntary food intake, even in animals fed ad libitum. The transformation from the summer into the thrifty winter phenotype is also evident in the physiology of digestion. Microbial protein synthesis is less facilitated by diminished phosphorus secretion into the shrunk rumen during winter. In line with this result, the concentration of ammonia, the end-product of protein digestion in the rumen, peaks in rumen liquid in spring, whereas the molar proportion of acetate, an indicator of fermentation of a diet rich in fiber, peaks in winter. In contrast to reduced stimulation of growth of ruminal microbes during winter, active transport of nutrients across the intestinal epithelium is increased, resulting in more efficient exploitation of the lower amount and quality of ingested winter feed. Nevertheless, the energy balance remains negative during winter. This is compensated by using fat reserves accumulated during summer, which become a major metabolic fuel during winter.


Assuntos
Regulação da Temperatura Corporal , Fibras na Dieta/metabolismo , Ingestão de Alimentos , Metabolismo Energético , Ruminantes/fisiologia , Aclimatação , Amônia/metabolismo , Ração Animal , Animais , Digestão , Fermentação , Temperatura Alta , Rúmen/metabolismo , Estações do Ano , Termogênese
20.
PLoS One ; 15(2): e0229335, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084208

RESUMO

Acclimation resulting from low- to moderate-intensity physical exertion in the heat induces several thermoregulatory adaptations, including slower exercise-induced increases in core body temperature. However, few studies have investigated the thermoregulatory adaptations induced by high-intensity interval training (HIIT) protocols. Thus, the present study aimed to compare the adaptations in rats' thermoregulatory parameters and aerobic performance observed after two different heat acclimation regimens consisting of HIIT protocols performed in a hot environment. Twenty-three adult male Wistar rats were initially subjected to an incremental-speed exercise at 32°C until they were fatigued and then randomly assigned to one of the following three heat acclimation strategies: passive heat exposure without any exercise (untrained controls-UN; n = 7), HIIT performed at the maximal aerobic speed (HIIT100%; n = 8) and HIIT performed at a high but submaximal speed (HIIT85%; n = 8). Following the two weeks of interventions, the rats were again subjected to a fatiguing incremental exercise at 32°C, while their colonic temperature (TCOL) was recorded. The workload performed by the rats and their thermoregulatory efficiency were calculated. After the intervention period, rats subjected to both HIIT protocols attained greater workloads (HIIT100%: 313.7 ± 21.9 J vs. HIIT85%: 318.1 ± 32.6 J vs. UN: 250.8 ± 32.4 J; p < 0.01) and presented a lower ratio between the change in TCOL and the distance travelled (HIIT100%: 4.95 ± 0.42°C/km vs. HIIT85%: 4.33 ± 0.59°C/km vs. UN: 6.14 ± 1.03°C/km; p < 0.001) when compared to UN rats. The latter finding indicates better thermoregulatory efficiency in trained animals. No differences were observed between rats subjected to the two HIIT regimens. In conclusion, the two HIIT protocols induce greater thermoregulatory adaptations and performance improvements than passive heat exposure. These adaptations do not differ between the two training protocols investigated in the present study.


Assuntos
Adaptação Fisiológica/fisiologia , Regulação da Temperatura Corporal/fisiologia , Treinamento Intervalado de Alta Intensidade/métodos , Temperatura Alta , Condicionamento Físico Animal/fisiologia , Esforço Físico/fisiologia , Animais , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
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