Effect of moderate and severe heat stress on avian embryonic Hsp70 gene expression

Stress response is a universal mechanism developed by all organisms to deal with adverse changes in the environment, which lead to the synthesis of heat shock proteins (Hsps). In this study, the effect of moderate (41degreesC) and severe (44degreesC) heat stress on Hsp70 transcript expression pattern was investigated during chicken embryogenesis. Acute exposure to severe heat stress for one hour resulted in a fifteen-fold increase in Hsp70 mRNA levels. The return of stressed embryos to normal incubation temperature resulted in Hsp70 mRNA levels five-fold higher than control after three hours and normal levels after six hours. Moderate heat stress did not induce enhancements on Hsp70 mRNA levels. The spatial expression of Hsp70 transcripts was detected in embryos under normal incubation conditions. Whole-mount in situ hybridization analysis showed that Hsp70 transcripts were constitutively present in somite and in distinct encephalic domains (predominantly in prosencephalon and mesencephalon areas) of the chicken embryo. These results showed that Hsp70 induction is dependent on incubation temperature conditions, suggesting that early chicken embryos may induce a quick emergence response to cope with severe heat stress by increasing Hsp70 mRNA levels.

Performance and carcass characteristics of broiler chickens with different growth potential and submitted to heat stress

In order to evaluate the effects of broiler genotype and of heat exposure on performance, carcass characteristics, and protein and fat accretion, six hundred one-day-old male broilers were randomly assigned in a 2 x 3 factorial arrangement, according to the following factors: genetic group (selected and non-selected broilers) and pair-feeding scheme (Ad(32) - reared under heat stress and fed ad libitum; Ad(23) - reared at thermoneutrality and fed ad libitum; Pf(23) - reared at thermoneutrality and pair fed with Ad(32)), with a total of six treatments with four replicates of 25 birds each. Independent of pair-feeding scheme, selected broilers showed better feed conversion, higher carcass yield, and lower abdominal fat deposition rate. However, as compared to non-selected broilers, they reduced more intensively feed intake when heat exposed, which promoted significant breast-yield decrease, and more pronounced changes on carcass chemical composition. These findings allows concluding that, in both genetic groups, both environmental temperature and feed-intake restriction influence abdominal fat deposition rate and other carcass characteristics; however, the impact of heat exposure on broiler performance is more noticeable on the selected line.

Energy Expenditure, Lipid Profile, Oxidative Stress, and Cardiac Energy Metabolism After Growth Hormone Treatment in Obese Young Rats

Obesity is rampant in modern society and growth hormone (GH) could be useful as adjunct therapy to reduce the obesity-induced cardiovascular damage. To investigate GH effects on obesity, initially 32 male Wistar rats were divided into two groups (n = 16): control (C) was fed standard-chow and water and hyper-caloric (H) was fed hypercaloric chow and 30% sucrose in its drinking water. After 45 days, both C and H groups were divided into two subgroups (n = 8): C + PL was fed standard-chow, water and received saline subcutaneously; C + GH was fed standard-chow, water, and received 2 mg/kg/day GH subcutaneously; H + PL was fed hypercaloric diet, 30% sucrose in its drinking water, and received saline subcutaneously; and H + GH was fed hypercaloric diet, 30% sucrose in its drinking water, and received GH subcutaneously. After 75 days of total experimental period, H + PL rats were considered obese, having higher body weight, body mass index, Lee-index, and atherogenic index (AI) compared to C + PL. Obesity was accompanied by enhanced myocardial lipid hydroperoxide (LH) and lactate dehydrogenase (LDH), as well of depressed energy expenditure (RMR) and oxygen consumption(VO(2))/body weight. H + GH rats had higher fasting RMR, as well as lower AI and myocardial LH than H + PL. Comparing C + GH with C + PL, despite no effects on morphometric parameters, lipid profile, myocardial LH, and LDH activity, GH enhanced fed RMR and myocardial pyruvate dehydrogenase. In conclusion, the present study brought new insights into the GH effects on obesity related cardiovascular damage demonstrating, for the first time, that GH regulated cardiac metabolic pathways, enhanced energy expenditure and improved the lipid profile in obesity condition. Growth hormone in standard fed condition also offered promising therapeutic value enhancing pyruvate-dehydrogenase activity and glucose oxidation in cardiac tissue, thus optimizing myocardial energy metabolism.

Improvement in the fatigue strength of chromium electroplated AISI 4340 steel by shot peening

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nutritional stress enhances cell viability of odontoblast-like cells subjected to low level laser irradiation

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

Growth hormone and heart failure: Oxidative stress and energetic metabolism in rats

Several evidences point for beneficial effects of growth hormone (GH) in heart failure (HF). Taking into account that HF is related with changes in myocardial oxidative stress and in energy generation from metabolic pathways, it is important to clarify whether GH increase or decrease myocardial oxidative stress and what is its effect on energetic metabolism in HF condition. Thus, this study investigated the effects of two different doses of GH on energetic metabolism and oxidative stress in myocardium of rats with HF. Male Wistar rats (n = 25) were submitted to aortic stenosis (AS). The HF was evidenced by tachypnea and echocardiographic criteria around 28 weeks of AS. The rats were then randomly divided into three groups: (HF) with HF, treated with saline (0.9% NaCl); (HF-GHI), treated with 1 mk/kg/day recombinant human growth hormone (rhGH), and (HF-GH2) treated with 2 mg/kg/day rhGH. GH was injected, subcutaneously, daily for 2 weeks. A control group (sham; n = 12), with the same age of the others rats was evaluated to confirm data for AS. HF had lower IGF-I (insulin-like growth factor-I) than sham-operated rats, and both GH treatments normalized IGF-I level. HF-GH1 animals had lower lipid hydroperoxide (LH), LH/total antioxidant substances (TAS) and glutathione-reductase than HF. Glutathione peroxidase (GSH-Px), hydroxyacyl coenzyme-A dehydrogenase, lactate dehydrogenase(LDH) were higher in HF-GH1 than in HF. HF-GH2 compared with HF, had increased LH/TAS ratio, as well as decreased oxidized glutathione and LDH activity. Comparing the two GH doses, GSH-Px, superoxide dismutase and LDH were lower in HF-GH2 than in HF-GHI. In conclusion, GH effects were dose-dependent and both tested doses did not aggravate the heart dysfunction. The higher GH dose, 2 mg/kg exerted detrimental effects related to energy metabolism and oxidative stress. The lower dose, 1 mg/kg GH exerted beneficial effects enhancing antioxidant defences, reducing oxidative stress and improving energy generation in myocardium of rats with heart failure. (c) 2007 Elsevier Ltd. All rights reserved.

Growth performance of Nile tilapia, Oreochromis niloticus, fed diets containing levels of pyridoxine and haematological response under heat stress

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

Ultraviolet-B and water stress effects on growth, gas exchange and oxidative stress in sunflower plants

The effects and interaction of drought and UV-B radiation were studied in sunflower plants (Helianthus annuus L. var. Catissol-01), growing in a greenhouse under natural photoperiod conditions. The plants received approximately 1.7 W m(-2) (controls) or 8.6 W m(-2) (+UV-B) of UV-B radiation for 7 h per day. The UV-B and water stress treatments started 18 days after sowing. After a period of 12 days of stress, half of the water-stressed plants (including both UV-B irradiated or non-irradiated) were rehydrated. Both drought and UV-B radiation treatments resulted in lower shoot dry matter per plant, but there was no significant interaction between the two treatments. Water stress and UV-B radiation reduced photosynthesis, stomatal conductance and transpiration. However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercelluar CO(2) concentration was initially reduced in all treatments compared to control plants but it increased with time. Photosynthetic pigments were not affected by UV-B radiation. Water stress reduced photosynthetic pigments only under high UV-B radiation. The decrease was more accentuated for chlorophyll a than for chlorophyll b. As a measure for the maximum efficiency of photosystem II in darkness F (v)/F (m) was used, which was not affected by drought stress but initially reduced by UV-B radiation. Independent of water supply, UV-B radiation increased the activity of pirogalol peroxidase and did not increase the level of malondialdehyde. on the other hand, water stress did not alter the activity of pirogalol peroxidase and caused membrane damage as assessed by lipid peroxidation. The application of UV-B radiation together with drought seemed to have a protective effect by lowering the intensity of lipid peroxidation caused by water stress. The content of proline was not affected by UV-B radiation but was increased by water stress under both low and high UV-B radiation. After 24 h of rehydration, most of the parameters analyzed recovered to the same level as the unstressed plants.

Toward a hierarchical concept of plant stress

A number of attempts have been made to obtain a clear definition of biological stress. However, in spite of the efforts, some controversies on the concept of plant stress remain. The current versions are centered either on the cause (stress factor) or on the effect (stress response) of environmental stress. The objective of this study was to contribute to the definition of stress, using a hierarchical approach. Thus, we have performed an analysis of the most usual stress concepts and tested the relevance of considering different observation scales in a study on plant response to water deficit. Seedlings of Eucalyptus grandis were grown in vitro at water potentials ranging from -0.16 to -0.6 MPa, and evaluated according to growth and biochemical parameters. Data were analyzed through principal component analysis (PCA), which pointed to a hierarchical organization in plant responses to environmental disturbances. Growth parameters (height and dry weight) are more sensitive to water deficit than biochemical ones (sugars, proline, and protein), suggesting that higher hierarchical levels were more sensitive to environmental constraints than lower hierarchical ones. We suggest that before considering an environmental fluctuation as stressful, it is necessary to take into account different levels of plant response, and that the evaluation of the effects of environmental disturbances on an organism depends on the observation scale being used. Hence, a more appropriate stress concept should consider the hierarchical organization of the biological systems, not only for a more adequate theoretical approach, but also for the improvement of practical studies on plants under stress.

Effect of acute heat stress on heat shock protein 70 messenger RNA and on heat shock protein expression in the liver of broilers

1. The synthesis of heat shock protein 70 (Hsp70) mRNA and the expression of Hsp70 in the liver of broiler chickens submitted to acute heat stress (35 degrees C for 5 h) was investigated.2. Hsp70 expression was detected by SDS-PAGE and Western blot analysis using a polyclonal antiserum against Hsp70 of Blastocladiella emersonii. The specific signal of Hsp70 mRNA was analysed by Northern blot using as probe a Hsp70 cDNA of B. emersonii.3. An increase in the amount of Hsp70 was detected from the first up to the fifth hour of acute heat exposure. This increase in the amount of Hsp70 was accompanied by an increase in Hsp70 mRNA which peaked at 3 h.4. This study shows that the heat induced increase in Hsp70 mRNA and protein in broiler liver, in vivo, are time dependent, similar to that in mammals.

HETEROGENEOUS GROWTH IN THE NILE TILAPIA - SOCIAL STRESS AND CARBOHYDRATE-METABOLISM

Increase in heterogeneous growth as a result of grouping in the Nile tilapia, Oreochromis niloticus (L.), is presumed to be partially promoted by the social stress imposed by the dominant fish on the subordinates. Such stress may decrease the energy available for growth. In this study, the effect of social stress on carbohydrate metabolism was studied in adult, growing males. All animals were deprived of food during the experimentation period and pairing was imposed for either 2 or 4 days. Glycemia was measured before and after pairing, and muscle and liver glycogen contents were determined only after pairing. Subordinate fish showed the highest consumption of carbohydrate reserves. This response was caused by the social stress imposed which corroborates the idea that metabolic differences promoted by social stress may be involved in the rouping effect on heterogeneous growth in the Nile tilapia.

Influence of ambient gas on the growth and properties of porous tin-doped indium oxide thin films made by pulsed laser deposition

The laser ablation method was used for depositing porous nanocrystalline indium-tin oxide thin films for gas sensing applications. Samples were prepared at different pressures using three gases (O-2, 0.8N(2):0.2O(2), N-2) and heat-treated in the same atmosphere used for the ablation process. X-ray diffraction results show that the films are not oriented and the grain sizes are in the range between 15 and 40 nm. The grains are round shaped for all samples and the porosity of the films increases with the deposition pressure. The degree of sintering after heat treatment increases for lower oxygen concentrations, generating fractures on the surface of the samples. Film thicknesses are in the range of I pm for all gases as determined from scanning electron microscopy cross-sections. Electrical resistance varies between 36.3 ohm for the film made at 10 Pa pressure in N-2 until 9.35 x 10(7) ohm for the film made at 100 Pa in O-2. (C) 2007 Elsevier B.V. All rights reserved.

Expression of heat shock protein in broiler embryo tissues after acute cold or heat stress

This study evaluated the expression of heat shock protein 70 kD (hsp70) in broiler chicken embryos subjected to cold (Experiment 1) or high incubation temperature (Experiment 11). In each experiment, fertile eggs were distributed in three incubators kept at 37.8degreesC. At day 13 (D13), D16, and D19 of incubation, the embryos were subjected to acute cold (32degreesC) or heat (40degreesC) for 4-6 hr. Immediately after cold or heat exposure, samples from the liver, heart, breast muscle, brain, and lungs of 40 embryos were taken per age and treatment (control or stressed embryos), A tissue pool from 10 embryos was used as 1 replication. The levels of hsp70 in each tissue sample was quantified by Western blot analysis. The data were analyzed in a 3 x 2 factorial arrangement of treatments with four replications. hsp70 was detected in all embryo tissues, and the brain contained 2- to 5-times more hsp70 protein compared to the other tissues in either cold or heat stressed embryos. hsp70 increases were observed in the heart and breast muscle of cold stressed embryos at D16 and D19, respectively. Heat stressed embryos showed an increase of hsp70 in the heart at D13 and D19, and in the lung at D19 of incubation. Younger embryos had higher hsp70 synthesis than older embryos, irrespective of the type of thermal stressor. The results indicate that the expression of hsp70 in broiler chicken embryos is affected by cold and heat distress, and is tissue- and age-dependent. (C) 2004 Wiley-Liss, Inc.

EFFECT OF TREATMENT WITH GROWTH-REGULATORS AND SCARIFICATION ON THE TOLERANCE TO WATER-STRESS IN SEEDS OF ORYZA-SATIVA LCVIAC-165

The effect of treatment of seeds of Oryza sativa L. cv. IAC 165 with gibberellic acid, 6-benzyladenine and ethrel on the tolerance to the water stress were analysed. Gibberellic acid had no effect and 6-benzyladenine and ethrel promoted slight increase in the tolerance to water stress, specially in darkness. After scarification, those growth regulator presented no effect. Our results suggest that 6-benzyladenine and ethrel promoted water stress tolerance due to the decrease in the resistance of the seed coat to embryo expansion.