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Efeitos do estresse térmico por calor sobre os índices zootécnicos, a integridade do trato intestinal e a imunidade inata em frangos de corte; Effects of heat stress on performance parameters, intestinal morphology and innate immunity in broiler chickens

Quinteiro Filho, Wanderley Moreno
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/01/2009 Português
Relevância na Pesquisa
67.49247%
Os conceitos de bem-estar animal são uma realidade dentro da avicultura mundial. Sabe-se que aves estressadas apresentam diminuição no crescimento e na conversão alimentar, desajustes fisiológicos e hormonais, bem como aumento da suscetibilidade a doenças em decorrência de modificações induzidas pelo estresse na resposta imune. Além disso, eventos estressantes vêm sendo relacionados com distúrbios na integridade da microbiota intestinal. Nesse sentido, buscamos neste trabalho estudar os efeitos do estresse térmico por calor nas temperaturas de 26±1ºC, 31±1ºC e 36±1ºC sobre os índices zootécnicos, a integridade intestinal e a imunidade inata de frangos de corte, correlacionado e discutindo os achados experimentais dentro de uma perspectiva neuroimune. Nossos resultados mostraram que o estresse por calor (31±1ºC e 36±1ºC) em frangos de corte: (1) diminuiu o ganho de peso e o consumo de ração, porém só observamos diminuição da conversão alimentar e da mortalidade nas aves submetidas ao estresse de 36±1ºC; (2) diminuiu o peso relativo da bursa de Fabrícius, porém apenas a temperatura de 36±1ºC diminuiu o peso relativo do timo; (3) diminuiu o burst oxidativo basal de macrófagos, porém apenas a temperatura de 31±1ºC foi capaz de diminuir o burst oxidativo dessa célula na presença de S. aureus. (4) aumentou os níveis séricos de corticosterona; e (5) observamos presença de discreta enterite caracterizada por aumento de infiltrado inflamatório linfo-plasmocitario na lamina própria do jejuno. Tomados em seu conjunto...

Efeitos do estresse por calor sobre a imunidade e a migração de Salmonela enteritidis em frangos de corte; Effects of heat stress on immunity and Salmonella enteritidis invasion in broiler chickens

Quinteiro Filho, Wanderley Moreno
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/03/2013 Português
Relevância na Pesquisa
67.57857%
O estresse é uma realidade na produção avícola mundial. Sabe-se que ambientes estressores prejudicam o bem-estar, os parâmetros produtivos e a imunidade de frangos de corte. Sabe-se, também, que o estresse por calor diminui a atividade de macrófagos em frangos de corte e, que existem, inúmeros estressores ambientais que insidem sobre a produção animal e podem aumentar a susceptibilidade às doenças. A Salmonella spp. é uma das maiores zoonoses do mundo, causando mais de 1 bilhão de casos de infecção. Nesse sentido, o presente trabalho analisa os efeitos do estresse por calor (31±1°C) sobre os índices zootécnicos, a imunidade, a invasão bacteriana e a integridade intestinal em frangos de corte infectados com Salmonella enteritidis; os dados obtidos foram discutidos dentro de uma perspectiva neuroimune. Os frangos foram divididos em quatro grupos: 1) Controle (C); 2) Estresse por Calor a 31±1 °C (HS31°C); 3) Controle infectados com Salmonella enteritidis (Controle Positivo [PC]) e; 4) Estresse por calor a 31±1 °C e infectados com Salmonella (PHS31°C). Nossos resultados mostraram que o estresse por calor em uma situação de infecção experimental por Salmonella enteritidis (grupo PHS31°C) 1) diminuiu os índices zootécnicos; especificamente...

A baixa fertilidade de vacas Holandesas (B. taurus) repetidoras de serviço durante o estresse térmico está relacionada à sua baixa competência oocitária; The low fertility of repeat-breeder Holstein (B. taurus) cows during summer heat stress is related to a low oocyte competence

Ferreira, Roberta Machado
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/06/2012 Português
Relevância na Pesquisa
67.4991%
O objetivo desse estudo foi avaliar se a baixa fertilidade de vacas Holandesas repetidoras de serviço [RS; comparativamente a novilhas (NOV) e vacas próximas ao pico de lactação (PL)] está associada com comprometimento da qualidade oocitária e se esta condição é agravada pelo estresse térmico. Fêmeas das três categorias foram tratadas com o mesmo protocolo de sincronização da emergência de onda folicular. Cinco dias após o início do protocolo, a ovum pick-up (OPU) foi realizada e foram avaliados (Capítulo; Cap. 1) o número de folículos ovarianos, de oócitos totais e viáveis, temperatura retal (TR), temperatura de superfície cutânea (TC) e frequência respiratória (FR). Os oócitos viáveis foram utilizados para a produção in vitro de embriões (Cap. 2) e avaliações biomoleculares (Cap. 3). No Cap. 2, foram avaliados o desenvolvimento embrionário (taxa de clivagem, de blastocisto e de eclosão) e a qualidade dos embriões produzidos (número de células e frequência de núcleos fragmentados). No Cap. 3, realizou-se a extração de RNA e DNA de parte dos oócitos coletados para a quantificação relativa e absoluta de DNA mitocondrial (mtDNA) e a avaliação da expressão de genes relacionados à replicação/transcrição do mtDNA (PPARGC1A...

Avaliação dos efeitos do estresse por calor sobre a atividade de linfócitos e a resposta vacinal ao paramixovírus (Doença de Newcastle) em frangos de corte; Effects of heat stress on lymphocytes activity and vaccine response to paramyxovirus (Newcastle Disease) in broiler chicken

Honda, Bruno Takashi Bueno
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/08/2013 Português
Relevância na Pesquisa
67.588706%
Uma série de fatores como ambiente, nutrição e doenças podem ser consideradas como estressores em sistemas de produção. Frangos de corte expostos a estressores por períodos prolongados de tempo apresentam de forma geral, redução do ganho de peso e consumo de ração, aumento da conversão alimentar, aumento da média de mortalidade e predisposição a doenças. A vacinação é uma prática essencial para um adequado manejo da produção e o desenvolvimento da imunidade do frango de corte frente a desafios bacterianos e virais presentes no ambiente. O entendimento dos fatores que podem interferir com o sucesso da vacinação é essencial para a otimização da saúde e do bem-estar animal, permitindo a utilização de todo o seu potencial genético e nutricional. Poucos estudos têm enfatizado o efeito do estresse por calor na imunidade celular e humoral de frangos de corte. Este trabalho tem como objetivo estudar o efeito do estresse por calor sobre a imunidade celular (linfócitos B e T), humoral sérica (IgM e IgY) e o peso relativo de órgãos (baço, bursa e fígado) de frangos de corte submetidos a um protocolo de vacinação para a Doença de Newcastle (cepa LaSota). Para tanto, 96 frangos de corte Cobb machos foram aleatoriamente divididos em quarto grupos: grupo 1. Frangos de corte não vacinados expostos à temperatura termoneutra; grupo 2. Frangos de corte vacinados expostos à temperatura termoneutra; grupo 3. Frangos de corte não vacinados expostos ao protocolo de estresse térmico por calor (38±2°C); e grupo 4. Frangos de corte vacinados expostos ao protocolo de estresse térmico por calor (38±2°C). Todas as aves foram alojadas em isoladores com água e ração ad libitum. Foi utilizada uma vacina com o vírus atenuado para Doença de Newcastle (cepa LaSota) administrada em duas doses...

Brain and hepatic Hsp70 protein levels in heat-acclimated broiler chickens during heat stress

Guerreiro, EN; Giachetto, PF; Givisiez, PEN; Ferro, JA; Ferro, MIT; Gabriel, Jane Eyre; Furlan, Renato Luis; Macari, Marcos
Fonte: Fundação APINCO de Ciência e Tecnologia Avícolas Publicador: Fundação APINCO de Ciência e Tecnologia Avícolas
Tipo: Artigo de Revista Científica Formato: 201-206
Português
Relevância na Pesquisa
67.536445%
In the present study we have investigated the effects of heat acclimation on brain and hepatic Hsp70 protein levels and body temperature of broiler chickens in response to gradual heat stress. Two groups of broilers were raised up to 47 days of age under distinct temperature conditions: thermoneutral (TN, according to bird age) or hot environmental (HS, 31-33°C). At 46 days of age, the birds reared at high ambient temperature were transferred to thermoneutrality conditions. After 18 h, these birds and the birds reared at thermoneutral temperature were submitted to gradual heat stress in a climatic chamber so that environment temperature was increased from 28 to 40ºC at a rate of 2ºC/h. Colonic temperature was measured using a thermometer sensor probe at each two hours, and hepatic and brain tissues were collected immediately after slaughter in order to assess Hsp70 protein level by Western blotting analysis. The colonic temperatures of birds reared at high temperature increased steeply during the first 2 h of heat stress (1.06ºC/h) and more slowly thereafter (0.59ºC/h). Broilers reared at thermoneutral temperature showed a small increase in the first 4 h of heat stress (0.18ºC/h) and then colonic temperature increased sharply (0.72ºC/h). Nevertheless...

Effect of thermal conditioning during embryonic development on aspects of physiological responses of broilers to heat stress

Moraes, VMB; Malheiros, R. D.; Bruggeman, V; Collin, A.; Tona, K.; Van As, P.; Onagbesan, O. M.; Buyse, J.; Decuypere, E.; Macari, Marcos
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 133-140
Português
Relevância na Pesquisa
67.488545%
The purpose of the present study was to investigate the effect of thermal conditioning, (through exposure to heat stress), during pre-hatch development on some physiological responses of post-hatch broilers to a post-natal heat stress challenge. Exposure to heat stress at this stage, we hope, may possibly induce epigenetic heat adaptation. Incubating eggs were exposed to temperature of 39.0degreesC for 2 h from Day 13 to 17 of incubation. At 33, 35, 37, 39, 41 and 43 d of age, the broilers hatched from these eggs were housed individually in open-circuit respiration cells. The climatic chambers were set to 22degreesC and increased to 30degreesC for 4 h. O-2 consumption and CO2 production of each chicken was monitored continuously in order to calculate the heat production. Blood samples were obtained before and during the 4 h heat stress. Thermal conditioning during incubation did not affect the plasma T-4, corticosterone, glucose, uric acid and CK concentrations. Temperature challenge, decreased plasma T-3 of broilers of both groups but the decrease was greater in pre-conditioned broilers compared with controls. A similar trend was observed for triglycerides. These changes did not affect total heat production. Since decreased T3 and triglyceride levels are part of the mechanisms for thermoregulation...

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram)

Borges, S. A.; Fischer Da Silva, A. V.; Majorka, A.; Hooge, D. M.; Cummings, K. R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1551-1558
Português
Relevância na Pesquisa
67.622646%
Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and waterrfeed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32°C in 30 min, 32 to 36°C in 30 min, 36 to 37°C in 15 min, and 37 to 41°C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 ± 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB O decreased blood Na and K, and DEB O and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB O and 240 results lower but similar statistically. In heat stress...

Effects of heat stress on development, quality and survival of Bos indicus and Bos taurus embryos produced in vitro

Silva, C. F.; Sartorelli, E. S.; Castilho, A. C S; Satrapa, R. A.; Puelker, R. Z.; Razza, E. M.; Ticianelli, J. S.; Eduardo, H. P.; Loureiro, B.; Barros, C. M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 351-357
Português
Relevância na Pesquisa
67.65522%
Heat stress is an important cause of poor development and low survival rates in bovine embryos. Experiments were conducted to test the hypothesis that Bos indicus embryos are more resistant to heat stress than are Bos taurus embryos. In experiment 1, Nelore and Jersey embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 6 hours), developmental ratios were assessed at Day 7 (Day 0 = day of fertilization), and blastocysts were frozen for RNA extraction. Experiment 2 evaluated expression of COX2, CDX2, HSF1, and PLAC8 in previously frozen blastocysts. In experiment 3, Nellore and Angus embryos from oocyte pick-up-derived oocytes were submitted to heat stress (96 hours post-insemination, 41 °C, 12 hours) and transferred to recipients on Day 7. In experiment 4, embryos developed as in experiment 3 were fixed for Terminal deoxynucleotidyl transferase dUTP nick end labeling labeling and total cell counting. In experiment 1, heat stress decreased the percentage of Jersey oocytes that became blastocysts, but had no effect on Nellore embryos (34.6%, 25.0%, 39.5%, and 33.0% for Jersey control, Jersey heat-stressed, Nellore control, and Nellore heat-stressed oocytes, respectively; P < 0.05). In experiment 2...

Evaporative heat loss in Bos taurus: Do different cattle breeds cope with heat stress in the same way?

Pereira, Alfredo; Titto, Evaldo; Infante, Paulo; Titto, Cristiane; Geraldo, Ana; Alves, Alexandre; Leme, Thays; Baccari Jr., Flávio; Almeida, José
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
67.604717%
The aim of this study was to compare two Portuguese (Alentejana and Mertolenga) and two exotic (Frisian and Limousine) cattle breeds in terms of the relationship between the increase in ambient temperature and the responses of the pathways of evaporative heat loss and the effects on homeothermy. In the experiment, six heifers of the Alentejana, Frisian, and Mertolenga breeds and four heifers of the Limousine breed were used. The animals were placed in four temperature levels, the first one in thermoneutral conditions and the other ones with increase levels of thermal stress. The increase in chamber temperatures had different consequences on the animals of each breed. When submitted to severe heat stress, the Frisian animals developed high thermal tachypnea (125 mov/min) and moderate sweating rates (117 g.m-2.h-1), which did not prevent an increase in the rectal temperature (from 38.4°C to 40.0°C). The Alentejana and Limousine breeds showed intermediate thermoregulatory reactions, with moderate increases in rectal temperature, especially during the period of greatest heat stress (from 38.6°C to 39.4°C and from 38.87°C to 39.4°C for Limousine and Alentejana, respectively). However, the importance and the intensity of evaporative heat loss pathways were different. The Limousine breed showed moderate levels of tachypnea (101 mov/min) while showing the lowest rates of sweating (95 g.m-2.h-1)...

Biomarkers for seasonal heat stress: A holistic approach

Pinheiro, Pinheiro, C; Lamy, Lamy, E; Pereira, Pereira, A
Fonte: Knight, C. H. (Ed) Publicador: Knight, C. H. (Ed)
Tipo: Aula
Português
Relevância na Pesquisa
67.61816%
Environmental heat stress, present during the hot and dry summers in Mediterranean climate, severely impairs animal’s performance, particularly in animals of high genetic merit. Although heat stress has been considerable studied in dairy cattle, the mechanisms of seasonal acclimation are less well understood. Besides, in Mediterranean region, there are also great interests in small ruminant dairy species, which are even less well studied. Biomarkers may have great potential in identifying levels of thermal stress. Although often referred, blood cortisol does not allow a full understanding of heat stress, due to its circadian cycle and because the confounding with other types of stress. Consequently, new and better non-invasive methods, than allow to assess stress, are necessary. The hair, faeces or saliva fulfil these requirements. Salivary proteins have been extensively studied in humans, due to their potential as non-invasive biomarkers of pathology and physiology. Nonetheless, in the last years, some research emerged demonstrating the value of saliva for farm animal studies. Based on previous line of research, on ruminant salivary proteome and heat stress, we propose to search for salivary and faeces biomarkers of seasonal acclimation to heat stress and to compare them with other well-known physiological and endocrine indicators. Unlike what occurs at tropical climates where animals must combine a high heat tolerance with high performance; in Mediterranean climate due to high climate seasonality...

Biomarkers for seasonal heat stress

Pinheiro, C.; Lamy, E.; Pereira, A.M.F.
Fonte: The First Dairy Care Conference Publicador: The First Dairy Care Conference
Tipo: Aula
Português
Relevância na Pesquisa
67.60452%
Environmental heat stress, present during the hot and dry summers in Mediterranean climate, severely impairs animal’s performance, particularly in animals of high genetic merit. Although heat stress has been considerable studied in dairy cattle, the mechanisms of seasonal acclimation are less well understood. Biomarkers may have great potential in identifying levels of thermal stress. The blood cortisol does not allow a full understanding of the levels of thermal stress, due to its circadian cycle and because the confounding with other types of stress. Furthermore, it should find non-invasive methods better to assess the stress. The hair, faeces or saliva fulfil these requirements. Saliva has been extensively studied in humans, due to its potential as a non-invasive source of pathology and physiology biomarkers. Nonetheless, in the last years, some research emerged demonstrating the value of this fluid for farm animal studies. Based on previous line of research, on ruminant salivary proteome and heat stress, we propose to search for salivary and faeces biomarkers of seasonal acclimation to heat stress and to compare them with other well-known physiological and endocrine indicators. Contrary to what occurs in tropical climates, where it seeks to match the performance with heat tolerance in Mediterranean climate looking up the physiological versatility. The aim of the study is: i) the identification of reliable biomarkers (saliva...

Functional genomic analysis of heat stress in Vitis vinifera

Diz, Raimundo Maximino Martins
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em /01/2015 Português
Relevância na Pesquisa
67.56724%
Grapevine (Vitis vinifera) is one of most agro-economically important fruit crops worldwide, with a special relevance in Portugal where over 300 varieties are used for wine production. Due to global warming, temperature stress is currently a serious issue affecting crop production especially in temperate climates. Mobile genetic elements such as retrotransposons have been shown to be involved in environmental stress induced genetic and epigenetic modifications. In this study, sequences related to Grapevine Retrotransposon 1 (Gret1) were utilized to determine heat induced genomic and transcriptomic modifications in Touriga Nacional, a traditional Portuguese grapevine variety. For this purpose, growing canes were treated to 42 oC for four hours and leaf genomic DNA and RNA was utilized for various techniques to observe possible genomic alterations and variation in transcription levels of coding and non-coding sequences between non-treated plants and treated plants immediately after heat stress (HS-0 h) or after a 24 hour recovery period (HS-24 h). Heat stress was found to induce a significant decrease in Gret1 related sequences in HS-24 h leaves, indicating an effect of heat stress on genomic structure. In order to identify putative heat induced DNA modifications...

Effects of propofol on damage of rat intestinal epithelial cells induced by heat stress and lipopolysaccharides

Tang,J.; Jiang,Y.; Tang,Y.; Chen,B.; Sun,X.; Su,L.; Liu,Z.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 Português
Relevância na Pesquisa
67.62386%
Gut-derived endotoxin and pathogenic bacteria have been proposed as important causative factors of morbidity and death during heat stroke. However, it is still unclear what kind of damage is induced by heat stress. In this study, the rat intestinal epithelial cell line (IEC-6) was treated with heat stress or a combination of heat stress and lipopolysaccharide (LPS). In addition, propofol, which plays an important role in anti-inflammation and organ protection, was applied to study its effects on cellular viability and apoptosis. Heat stress, LPS, or heat stress combined with LPS stimulation can all cause intestinal epithelial cell damage, including early apoptosis and subsequent necrosis. However, propofol can alleviate injuries caused by heat stress, LPS, or the combination of heat stress and LPS. Interestingly, propofol can only mitigate LPS-induced intestinal epithelial cell apoptosis, and has no protective role in heat-stress-induced apoptosis. This study developed a model that can mimic the intestinal heat stress environment. It demonstrates the effects on intestinal epithelial cell damage, and indicated that propofol could be used as a therapeutic drug for the treatment of heat-stress-induced intestinal injuries.

Brain and hepatic Hsp70 protein levels in heat-acclimated broiler chickens during heat stress

Guerreiro,EN; Giachetto,PF; Givisiez,PEN; Ferro,JA; Ferro,MIT; Gabriel,JE; Furlan,RL; Macari,M
Fonte: Fundação APINCO de Ciência e Tecnologia Avícolas Publicador: Fundação APINCO de Ciência e Tecnologia Avícolas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 Português
Relevância na Pesquisa
67.536445%
In the present study we have investigated the effects of heat acclimation on brain and hepatic Hsp70 protein levels and body temperature of broiler chickens in response to gradual heat stress. Two groups of broilers were raised up to 47 days of age under distinct temperature conditions: thermoneutral (TN, according to bird age) or hot environmental (HS, 31-33°C). At 46 days of age, the birds reared at high ambient temperature were transferred to thermoneutrality conditions. After 18 h, these birds and the birds reared at thermoneutral temperature were submitted to gradual heat stress in a climatic chamber so that environment temperature was increased from 28 to 40ºC at a rate of 2ºC/h. Colonic temperature was measured using a thermometer sensor probe at each two hours, and hepatic and brain tissues were collected immediately after slaughter in order to assess Hsp70 protein level by Western blotting analysis. The colonic temperatures of birds reared at high temperature increased steeply during the first 2 h of heat stress (1.06ºC/h) and more slowly thereafter (0.59ºC/h). Broilers reared at thermoneutral temperature showed a small increase in the first 4 h of heat stress (0.18ºC/h) and then colonic temperature increased sharply (0.72ºC/h). Nevertheless...

Heat stress-induced memory impairment is associated with neuroinflammation in mice

Lee, Wonil; Moon, Minho; Kim, Hyo Geun; Lee, Tae Hee; Oh, Myung Sook
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
67.61401%
Background: Heat stress induces many pathophysiological responses and has a profound impact on brain structure. It has been demonstrated that exposure to high temperature induces cognitive impairment in experimental animals and humans. Although the effects of heat stress have long been studied, the mechanisms by which heat stress affects brain structure and cognition not well understood. Methods: In our longitudinal study of mice exposed to heat over 7, 14, or 42 days, we found that heat stress time dependently impaired cognitive function as determined by Y-maze, passive avoidance, and novel object recognition tests. To elucidate the histological mechanism by which thermal stress inhibited cognitive abilities, we examined heat stress-induced inflammation in the hippocampus. Results: In mice subjected to heat exposure, we found: 1) an increased number of glial fibrillary acid protein (GFAP)- and macrophage-1 antigen (Mac-1)-positive cells, 2) up-regulated nuclear factor (NF)-κB, a master regulator of inflammation, and 3) marked increases in cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cytokine interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the mouse hippocampus. We also observed that neuronal and synaptic densities were degenerated significantly in hippocampal regions after heat exposure...

Physiological studies on the response of wheat to short-term heat stress during reproductive development.

Talukder, A.S.M. Hasim Morshed
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
Relevância na Pesquisa
67.745923%
In Mediterranean environments, cereal crops are often exposed to short periods of elevated temperatures in spring when crops are approaching flowering and grain filling. Most studies on heat stress have focused on crop responses to extended periods of high temperature under controlled environment (CE) conditions possibly due to difficulties in applying heat stress in the field. It is possible wheat may respond quite differently to heat stress imposed under field and CE conditions. Therefore, experiments were designed to develop a methodology to apply heat treatments in the field. Studies were also undertaken to compare the response of wheat genotypes to a single-day heat stress event in the field and CE conditions. Wheat genotypes were exposed to heat stress for a single-day at two different stages, near flowering or green anther stage (H1), and early grain set or 7-10 days after anthesis (DAA) (H2) in 2009 and 2010. Heat treatment was applied in the field in a portable purpose-built heat chamber in which the temperature was steadily increased to a maximum of 35°C, which was maintained for 3 hours before being allowed to steadily decrease to the ambient temperature, like a typical natural spring heat event. Similar to the field studies...

Effects of Cerebral Blood Flow and PETCO2 on Cognitive Function During Passive Heat Stress

Watson, Cody Lang
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
67.50027%
This thesis tested whether cognitive performance during passive heat stress may be affected by changes in cerebrovascular variables as opposed to strictly thermally-induced changes. A pharmacological reduction in cerebral blood flow (CBF) using indomethacin along with a hypocapnia-induced CBF reduction during passive heat stress (Tre ~1.5°C above baseline) were used to investigate any cerebrovascular-mediated changes in cognitive performance. Repeated measures analysis of variance indicated that One-Touch Stockings of Cambridge (OTS) performance was not affected by a significant reduction in CBF during passive heat stress. More specifically, OTS accuracy measures did not change as a result of either a reduction in CBF or increasing passive heat stress. However, it was found that OTS response time indices improved with increasing passive heat stress independent of CBF changes. In conclusion, a significant reduction in CBF does not cause additional changes in performance of an executive functioning task during severe passive heat stress.

Srk1 kinase suppresses mitosis in response to heat stress in fission yeast

CHANDRASHEKHAR, MEGHA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
67.53629%
Fission yeast Srk1 kinase is essential for cellular responses to extracellular stimuli. It is activated downstream of the MAPK Spc1 and participates in controlling mitotic entry by directly phosphorylating and inhibiting Cdc25 phosphatase during the normal cell cycle and also in response to osmotic stress. Following phosphorylation, Cdc25 is exported out of the nucleus. Heat stress caused by a temperature shift from 25°C to 36°C, which is within the normal temperature tolerance of fission yeast, temporarily inhibits nuclear division in wildtype cells. The same response is seen in cells deleted for the Pyp1 and Pyp2 phosphatases which normally serve to down regulate the Spc1 stress response. I have shown that the transient block in nuclear division caused by temperature shifts within the physiological range does not occur in srk1- cells but instead there is a stimulation of mitosis and cell division in response to the heat stress. This pattern of mitotic stimulation is phenocopied in cdc25-9a cells where nine putative Srk1 phosphorylation sites on Cdc25 are changed to alanine. Cells lacking srk1, however, display the same cell cycle progression pattern as the wildtype cells in response to osmotic stress. This experiment clearly distinguishes separate pathways for these two stress responses. Also...

III.Heat stress in Triticum: kinetics of Na, K and P accumulation

Dias,Ana S.; Fernando,Ana L.; Lidon,Fernando C.
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 Português
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Genotypes of bread and durum wheat were submitted to heat stress after anthesis and the accumulation of Na, K and P, at booting, grain filling and maturity, were investigated. It was found that, after anthesis, the levels of Na in shoots were considerably higher in durum relatively to bread wheat, being this trend also observed in the total plant accumulation. In these genotypes, heat stress affected significantly Na concentration in shoots. In general, heat stressed plants had significant higher levels of K in the shoots and the proportion of this nutrient translocation from the roots also increased with heat stress. In general, the levels of P didn't show significant differences with heat stress. The effects of heat stress among the wheat genotypes life cycle are characterized and discussed.

Alterações celulares induzidas pelo estresse térmico em embriões bovinos; Cellular alterations induced by heat stress in bovine embryos

Lima, Rafaela Sanchez de; Assumpção, Mayra Elena Ortiz D’Avila; Visitin, José Antonio; Lopes, Fabíola Freitas de Paula
Fonte: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia Publicador: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 17/08/2014 Português
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Condições ambientais adversas, tais como altas temperaturas e umidade relativa, causam aumento da temperatura corporal interna (hipertermia) de vacas lactantes, que resultam em estresse térmico e diminuição dos índices de gestação. A susceptibilidade embrionária à temperatura elevada já foi bem caracterizada tanto em experimentos in vivo quanto in vitro. A exposição de embriões bovinos em estágios de zigoto e duas células à temperatura elevada diminui o desenvolvimento embrionário até o estágio de blastocisto. No entanto, o embrião torna-se mais resistente aos efeitos deletérios da temperatura elevada à medida que progride no desenvolvimento. A redução na competência de desenvolvimento embrionária causada pelo estresse térmico deve-se, em parte, às inúmeras alterações citoplasmáticas e nucleares induzidas pela temperatura elevada. No citoplasma embrionário, o choque térmico aumenta o número de mitocôndrias edemaciadas, desorganiza os microtúbulos e os filamentos de actina. No compartimento nuclear, a temperatura elevada induz a fragmentação de DNA característica de apoptose. Essa forma de morte celular é um fenômeno regulado ao longo do desenvolvimento embrionário pré-implantacional, visto que altas temperaturas não ativam a cascata de apoptose em embriões de duas ou quatro células. A apoptose embrionária induzida pelo choque térmico em embriões ≥ 16 células pode ser considerada um mecanismo de controle de qualidade para remoção dos blastômeros danificados...