Plant uncoupling mitochondrial proteins

Uncoupling proteins (UCPs) are membrane proteins that mediate purine nucleotide-sensitive free fatty acid-activated H(+) flux through the inner mitochondrial membrane. After the discovery of UCP in higher plants in 1995, it was acknowledged that these proteins are widely distributed in eukaryotic organisms. The widespread presence of UCPs in eukaryotes implies that these proteins may have functions other than thermogenesis. In this review, we describe the current knowledge of plant UCPs, including their discovery, biochemical properties, distribution, gene family, gene expression profiles, regulation of gene expression, and evolutionary aspects. Expression analyses and functional studies on the plant UCPs under normal and stressful conditions suggest that UCPs regulate energy metabolism in the cellular responses to stress through regulation of the electrochemical proton potential (Delta mu(H)+) and production of reactive oxygen species.

Thermogenic capacity of three species of fruit-eating phyllostomid bats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermogenic activity of growth hormone transgenic mice

The objective was to determine the effect of a mouse metallothionein/bovine growth hormone transgene on resting metabolic rate (RMR), cold-induced thermogenesis, and beta-agonist stimulated nonshivering thermogenesis in mice. Non-transgenic littermates were used as controls. Open-circuit indirect calorimetry was used to assess RMR and cold-induced thermogenesis in 64 mice. Air temperature in the chamber was set at 31 degrees C for RMR and was decreased to 28, 25, 21, or 17 degrees C to determine cold-induced thermogenesis. Response to the beta-agonist isoproterenol was evaluated by monitoring changes in colonic temperature of 34 mice upon injection of the drug or saline. Despite the fact that RMR tended to be lower in transgenics than in nontransgenics, at 31 degrees C transgenic mice were able to regulate colonic temperature at the same level as nontransgenics, but colonic temperature decreased in transgenics relative to nontransgenics as air temperature was reduced. For each degree decrease in air temperature between 31 and 17 degrees C, nontransgenic mice increased heat production by 1.03 +/- .10 watt/kg, whereas transgenic mice increased it by only .56 +/- .08 watt/kg, indicating that the thermogenic response of transgenics to cold was inferior. The magnitude of the maximal increase in colonic temperature after isoproterenol injection was similar for both groups, but the response was slower in transgenics. We suggest that lean body mass and substrate availability for shivering thermogenesis are reduced in transgenics relative to total body weight, and that they allow colonic temperature to decrease to conserve energy.

Effects of dietary macronutrient content on energy metabolism and uncoupling protein mRNA expression in broiler chickens

The objective of the present study was to investigate the effects of dietary macronutrient ratio on energy metabolism and on skeletal muscle mRNA expression of avian uncoupling protein (UCP), thought to be implicated in thermogenesis in birds. Broiler chickens from 2 to 6 weeks of age received one of three isoenergetic diets containing different macronutrient ratios (low-lipid (LL) 30 v. 77 g lipid/kg-, low-protein (LP) 125 v. 197 g crude protein (N X 6.25)/kg; low-carbohydrate (LC) 440 v. 520 g carbohydrate/kg). LP chickens were characterised by significantly lower body weights and food intakes compared with LL and LC chickens (-47 and -38% respectively) but similar heat production/kg metabolic body weight, as measured by indirect calorimetry, in the three groups. However, heat production/g food ingested was higher in animals receiving the LP diet (+41%, P<0.05). These chickens also deposited 57% less energy as protein (P<0.05) and 33% more as fat. No significant differences in energy and N balances were detected between LL and LC chickens. The diets with the higher fat contents (i.e. The LP and LC diets) induced slightly but significantly higher relative expressions of avian UCP mRNA in gastrocnemius muscle, measured by reverse transcription-polymerase chain reaction, than the LL diet (88 and 90 v. 78% glyceraldehyde-3-phosphate dehydrogenase respectively, P<0.05). Our present results are consistent with the recent view that UCP homologues could be involved in the regulation of lipid utilisation as fuel substrate and provide evidence that the macronutrient content of the diet regulates energy metabolism and especially protein and fat deposition.

Hypothalamic melanin-concentrating hormone is induced by cold exposure and participates in the control of energy expenditure in rats

Short-term cold exposure of homeothermic animals leads to higher thermogenesis and food consumption accompanied by weight loss. An analysis of cDNA-macroarray was employed to identify candidate mRNA species that encode proteins involved in thermogenic adaptation to cold. A cDNA-macroarray analysis, confirmed by RT-PCR, immunoblot, and RIA, revealed that the hypothalamic expression of melanin-concentrating hormone (MCH) is enhanced by exposure of rats to cold environment. The blockade of hypothalamic MCH expression by antisense MCH oligonucleotide in cold-exposed rats promoted no changes in feeding behavior and body temperature. However, MCH blockade led to a significant drop in body weight, which was accompanied by decreased liver glycogen, increased relative body fat, increased absolute and relative interscapular brown adipose tissue mass, increased uncoupling protein 1 expression in brown adipose tissue, and increased consumption of lean body mass. Thus, increased hypothalamic MCH expression in rats exposed to cold may participate in the process that allows for efficient use of energy for heat production during thermogenic adaptation to cold.

Food intake and thermic effect of feeding in thyroid-deficient pigs

Short and long-term thyroidectomy and Methimazole treatment reduced food intake in young growing pigs. The thermic effect of feeding assessed by the increment in rectal temperature after the beginning of food ingestion was reduced in thyroidectomized animals, but no effect could be observed in Methimazole-treated pigs. Propranolol injection after short-term treatment decreased food intake in sham-operated and treated animals, but reduced the thermic effect of feeding only in the thyroidectomized and Methimazole-treated pigs. Long-term treatment inhibited the effect of propranolol in reducing food intake and the thermic effect of feeding. On the basis of these data, it was suggested that the interaction between thyroid hormones and catecholamines (noradrenaline) plays an important role in the regulation of food intake and in the thermic effect of feeding in thyroid-deficient pigs.

Observations on the development of the febrile response to pyrogen in newborn pigs

The febrile response of newborn pigs to exogenous pyrogen injection was investigated. Lipopolysacharides (LPS, E coli) were injected intravenously into the superior vena cava of 1-30-day-old piglets. All the experiments were carried out in littermates half of which were injected with pyrogen and half with pyrogen-free saline. Newborn pigs did not develop a febrile response from 1 to 4 days of age; however, when the animals were 5 days old exogenous pyrogen determined a typical monophasic febrile response. A second intravenous injection of pyrogen into newborn pigs (1 day old) 24 h after the first did not raise body temperature. It is suggested that newborn pigs behave like the newborn of other mammalian species regarding endotoxin-induced thermogenesis.

Effects of acute cold exposure on rectal temperature, blood glucose and plasma free fatty acids in alloxan-diabetic rats

These experiments were carried out to study the effects of acute cold exposure (0-2°C/4 hr) on rectal temperature, blood glucose and plasma free fatty acids (FFA) in alloxan-diabetic rats. Male Wistar rats weighing 170-190 g were used and diabetes was induced by i.v. alloxan injection (40 mg/kg body wt). Cold exposure produced severe hypothermia in diabetic rats. After 4 hr of cold, blood glucose of diabetic rats was reduced from 296±16 to 86t±12 mg/dl (P<0.01), and FFA increased slightly, but was not statistically different (P>0.05) from the initial value. As expected, interscapular brown adipose tissue (IBAT) and retroperitoneal and epididymal white adipose tissues were significantly lower in diabetic than in control rats. Cold exposure reduced total IBAT lipids in control but not in diabetic animals. The results of this experiment suggest that diabetic rats were unable to maintain body temperature in the cold, probably because of a failure to generate an adequate amount of heat by nonshivering thermogenesis in brown adipose tissue.

Nonthermal activation of transient receptor potential vanilloid-1 channels in abdominal viscera tonically inhibits autonomic cold-defense effectors

An involvement of the transient receptor potential vanilloid (TRPV) 1 channel in the regulation of body temperature (T b) has not been established decisively. To provide decisive evidence for such an involvement and determine its mechanisms were the aims of the present study. We synthesized a new TRPV1 antagonist, AMG0347 [(E)-N-(7-hydroxy-5,6,7,8-tetrahydronaphthalen-1- yl)-3-(2-(piperidin-1-yl)-6-(trifluoromethyl)pyridin-3-yl)acrylamide], and characterized it in vitro. We then found that this drug is the most potent TRPV1 antagonist known to increase T b of rats and mice and showed (by using knock-out mice) that the entire hyperthermic effect of AMG0347 is TRPV1 dependent. AMG0347-induced hyperthermia was brought about by one or both of the two major autonomic cold-defense effector mechanisms (tail-skin vasoconstriction and/or thermogenesis), but it did not involve warmth-seeking behavior. The magnitude of the hyperthermic response depended on neither T b nor tail-skin temperature at the time of AMG0347 administration, thus indicating that AMG0347-induced hyperthermia results from blockade of tonic TRPV1 activation by nonthermal factors. AMG0347 was no more effective in causing hyperthermia when administered into the brain (intracerebroventricularly) or spinal cord (intrathecally) than when given systemically (intravenously), which indicates a peripheral site of action. We then established that localized intra-abdominal desensitization of TRPV1 channels with intraperitoneal resiniferatoxin blocks the T b response to systemic AMG0347; the extent of desensitization was determined by using a comprehensive battery of functional tests. We conclude that tonic activation of TRPV1 channels in the abdominal viscera by yet unidentified nonthermal factors inhibits skin vasoconstriction and thermogenesis, thus having a suppressive effect on T b. Copyright © 2007 Society for Neuroscience.

Expressão de genes relacionados à função mitocondrial em bovinos Nelore extremos para consumo alimentar residual

Pós-graduação em Genética e Melhoramento Animal - FCAV

Ecologia da polinização do buriti (Mauritia flexuosa L. – Arecaceae) na restinga de Barreirinhas, Maranhão, Brasil

O estudo das palmeiras nativas é importante por seu grande valor econômico e na manutenção das comunidades de várias espécies de vertebrados e invertebrados que se alimentam de seus frutos, sementes e folhas. A eficiência na produção dos frutos das palmeiras está diretamente relacionada com a presença de insetos polinizadores, principalmente besouros, abelhas e moscas. A palmeira Mauritia flexuosa, comumente conhecida como buriti, é a espécie mais abundante do Brasil e é também chamada de “árvore da vida”, por ser 100% utilizável. Este trabalho teve como objetivo contribuir para o conhecimento da ecologia da polinização do buriti em ambiente de restinga, no município de Barreirinhas, Maranhão, Brasil. Para tanto, obteve-se dados sobre fenologia reprodutiva, biologia floral, sistema reprodutivo e visitantes florais. Para o acompanhamento fenológico foram selecionados 25 indivíduos de cada sexo, os quais foram observados de agosto/2009 a outubro/2012. As fenofases de floração e frutificação foram relacionadas com as variáveis climáticas através de correlação de Spearman. O processo de abertura e longevidade floral foi acompanhado durante o pico de floração da espécie, verificando-se a viabilidade polínica, a receptividade estigmática, as regiões emissoras de odor e a ocorrência de termogênese. Para determinar o sistema reprodutivo foram feitos testes de polinização cruzada e apomixia. O transporte de grãos de pólen pelo vento foi observado, por meio de lâminas de vidros untadas com vaselina que permaneceram penduradas próximas às inflorescências pistiladas durante 24 horas. Os visitantes florais foram coletados através do ensacamento de 20 inflorescências de cada sexo, sendo classificados de acordo com a frequência e o comportamento. O buriti apresentou padrão fenológico anual, sincrônico e sazonal, com floração de agosto a novembro e pico de queda dos frutos em setembro, o que corresponde à estação seca, diferindo do observado na Amazônia, onde estes eventos fenológicos ocorreram na estação chuvosa. Esta diferença pode ser justificada pela grande disponibilidade de água na região, o que faz com que o buriti não necessariamente dependa das chuvas para florescer. Este fato foi evidenciado pela correlação significativa negativa das fenofases com a precipitação e com a umidade relativa. A forte incidência solar e a disponibilidade de água no ambiente contribuíram para o sucesso na floração e frutificação do buriti. Além disto, fatores bióticos podem ter exercido influência no comportamento fenológico, cuja estratégia reprodutiva adotada parece ser a sincronização da floração e da frutificação com a atividade dos polinizadores e dispersores. Dessa maneira a espécie garante a sua reprodução em um período ótimo para a germinação de sementes e estabelecimento de plântulas. O sistema reprodutivo do buriti é xenogâmico. O conjunto de características florais, aliado à abundância de pólen e ao forte odor leva a crer que essa palmeira tenha como principal estratégia de polinização a cantarofilia, porém o vento também possui grande importância na polinização. Além de apresentar polinização do tipo misto (ambofilia), as flores do buriti atraíram uma grande variedade de visitantes, cuja riqueza foi maior que a observada na Amazônia.

Overexpression of UCP1 in tobacco induces mitochondrial biogenesis and amplifies a broad stress response

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chicken hatchlings prefer ambient temperatures lower than their thermoneutral zone

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

TRPV4 activates autonomic and behavioural warmth-defence responses in Wistar rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diferentes doses de Triiodotironina (T3) aumentam a expressão gênica de leptina, adiponectina e TRα com o envolvimento da via fosfatidil inositol 3 quinase (PI3K) em adipócitos, 3T3-L1

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)