Evaluation of changes in lipid peroxidation, ROS production, surface structures, secondary metabolites and yield of linseed (Linum usitatissimum L.) under individual and combined stress of ultraviolet-B and ozone using open top chambers.

The individual and interactive effects of supplemental UV-B (sUV-B) (ambient + 7.2 kJ m-2 d-1) and elevated O3 (ambient + 10 ppb) were evaluated under field conditions using open top chambers on two cultivars, Padmini and T-397 of linseed (Linum usitatissimum L.). Mean monthly surface level of O3 concentrations varied from 27.7 ppb to 59.0 ppb during the experimental period. Both UV-B and O3 induced the production of ROS (H2O2 and O2.-), resulting in significant damage of membranes due to lipid peroxidation and electrolyte leakage. Synthesis of secondary metabolites (flavonoids, anthocyanin, lignin and wax) was also enhanced in all the treatments, whereas biomass and yield were reduced. Alterations in frequency of stomata and wax distribution were also observed through scanning electron microscopy (SEM). Cultivar Padmini was found to be more sensitive because of higher damage of membrane vis-a-vis reduction in biomass and seed yield. However, concentrations of flavonoids, anthocyanin, lignin and wax were higher in T-397, suggesting its relative resistance against applied stress. Combined exposure of sUV-B and O3 was less harmful, as compared to their individual treatment. Among the three treatments, O3 was found to be more detrimental for overall growth and sUV-B for economic yield.

Vascular adaptive responses to physical exercise and to stress are affected differently by nandrolone administration

Androgenic anabolic steroid, physical exercise and stress induce cardiovascular adaptations including increased endothelial function. The present study investigated the effects of these conditions alone and in combination on the vascular responses of male Wistar rats. Exercise was started at 8 weeks of life (60-min swimming sessions 5 days per week for 8 weeks, while carrying a 5 percent body-weight load). One group received nandrolone (5 mg/kg, twice per week for 8 weeks, im). Acute immobilization stress (2 h) was induced immediately before the experimental protocol. Curves for noradrenaline were obtained for thoracic aorta, with and without endothelium from sedentary and trained rats, submitted or not to stress, treated or not with nandrolone. None of the procedures altered the vascular reactivity to noradrenaline in denuded aorta. In intact aorta, stress and exercise produced vascular adaptive responses characterized by endothelium-dependent hyporeactivity to noradrenaline. These conditions in combination did not potentiate the vascular adaptive response. Exercise-induced vascular adaptive response was abolished by nandrolone. In contrast, the aortal reactivity to noradrenaline of sedentary rats and the vascular adaptive response to stress of sedentary and trained rats were not affected by nandrolone. Maximum response for 7-10 rats/group (g): sedentary 3.8 ± 0.2 vs trained 3.0 ± 0.2*; sedentary/stress 2.7 ± 0.2 vs trained/stress 3.1 ± 0.1*; sedentary/nandrolone 3.6 ± 0.1 vs trained/nandrolone 3.8 ± 0.1; sedentary/stress/nandrolone 3.2 ± 0.1 vs trained/stress/nandrolone 2.5 ± 0.1*; *P < 0.05 compared to its respective control. Stress and physical exercise determine similar vascular adaptive response involving distinct mechanisms as indicated by the observation that only the physical exercise-induced adaptive response was abolished by nandrolone.

Antioxidative response mechanisms in halophytes: their role in stress defence.

Normal growth and development of plants is greatly dependent on the capacity to overcome environmental stresses. Environmental stress conditions like high salinity, drought, high incident light and low or high temperature cause major crop losses worldwide. A common denominator in all these adverse conditions is the production of reactive oxygen species (ROS) within different cellular compartments of the plant cell. Plants have developed robust mechanisms including enzymatic or nonenzymatic scavenging pathways to counter the deleterious effects of ROS production. There are a number of general reviews on oxidative stress in plants and few on the role of ROS scavengers during stress conditions. Here we review the regulation of antioxidant enzymes during salt stress in halophytes, especially mangroves. We conclude that (i) antioxidant enzymes protect halophytes from deleterious ROS production during salt stress, and (ii) genetic information from mangroves and other halophytes would be helpful in defining the roles of individual isoforms. This information would be critical in using the appropriate genes for oxidative stress defence for genetic engineering of enhanced stress tolerance in crop systems.

Evaluation of adaptogenic activity profile of herbal preparation.

The herbal formulation, AVM is a proprietary formula that consists of extracts of herbs that have been used in Indian traditional medicine to promote physical and mental health, improve defense mechanisms of the body and enhance longevity. AVM (500 and 1000 mg/kg) was tested for its adaptogenic activity by determining antistress, anabolic and immunomodulatory effects. In antistress activity, pretreatment with AVM significantly attenuated the changes in ascorbic acid (from blood and adrenal), cortisol (from plasma and adrenal) and adrenal gland weights induced due to restrain stress (physical immobilization). Its antistress effect at 1000 mg/kg was comparable to that of diazepam (5 mg/kg) treated group. Leucopenia, and anemia induced by cyclophosphamide (CYP) was shown to reduce significantly by AVM. Treatment of AVM + CYP had increased spleen and thymus weights significantly as compared to CYP alone treated group. The anabolic activity was evaluated by weight gain of the levator ani muscle, ventral prostrate gland and seminal vesicles in rats as compared to untreated control.

Effects of the combined use of glutamine and growth hormone in the intestinal adaptation after massive resection of the small bowel in rats

OBJETIVO: Investigar os efeitos do uso combinado da glutamina (GL) e do hormônio do crescimento (GH) no intestino de ratos submetidos a ressecção de 80% do intestino delgado. MÉTODOS: Vinte e quatro ratos Wistar foram randomizados para receber uma a dieta padrão- grupo controle (GC, n=12) ou a mesma dieta adicionada de glutamina 4% (isocalórica, isoproteica) - grupo glutamina- hormônio do crescimento (GL-GH, n=12) após a enterectomia à 80%. Este último grupo recebeu por via sub-cutânea, 0,6 UI/dia de GH. Grupos de seis ratos cada foram sacrificados no 5º e 14º dias. As seguintes variáveis foram estudadas: peso corporal, peso de mucosa, histomorfometria e conteúdo de DNA no segmento ressecado inicialmente e no intestino adaptado coletado após o sacrifício. RESULTADOS: Todos os animais perderam peso até o 5º dia, estabilizando-se após esta data em ambos os grupos. Não houve diferença estatística no peso da mucosa associada a grupos ou datas. O peso da mucosa do íleo diminuiu dos dados iniciais para os finais, quando comparados a mucosa jejunal (p<0.02). O conteúdo de DNA aumentou dos dados iniciais para os finais (p=0.001) em ambos os grupos, porém, o aumento foi maior nos animais do grupo GL-GH (CG = 0.53 [95% CI, 0.44-0.62] g/cm-1 vs. GL-GH= 0.85 [95%CI, 0.76-0.94] g/cm-1; p<0.01), especialmente no 14º dia. O conteúdo de DNA no íleo foi significativamente maior que no jejuno (p=0.01). Houve um aumento significativo na espessura da parede e na profundidade da cripta, no grupo controle (p<0.01). CONCLUSÃO: A adaptação intestinal após ressecção extensa é melhorada com o uso combinado de glutamina e GH.

Effect of water stress and heavy metals on induction of somatic embryogenesis in wheat leaf base cultures.

In vitro cultures of plant tissues are known to mimic the response of field-grown plants when subjected to stress treatments. This investigation on Triticum aestivum explores the effect of drought stress on somatic embryogenesis and endogenous proline content. Leaf bases were cultured on MS medium supplemented with 2,4-D (10 microM) and different concentrations of PEG (2.5, 5, 7.5%) or mannitol (0.25 and 0.5 M) and also subjected to different periods of aerial drying in the laminar flow for one-day and subsequently transferred to MS basal medium. PEG treatment induced a high percentage (up to 50%) of embryoid formation. However, with mannitol and aerial drying, percentage of embryoid formation decreased with increasing concentrations and duration. After ten days, the endogenous proline content of explants treated with different concentrations of PEG, mannitol and different durations of aerial drying increased with increasing concentration and increasing duration of the treatment, thus, corroborating the role of proline as an osmolyte during stress conditions. Similarly, addition of metals such as cadmium and cobalt caused a reduction in percentage explants depicting embryogenesis. However, when cadmium was employed alone, 22% explants displayed somatic embryogenesis as compared to 54% in 2,4-D treated cultures.

Antioxidant tolerance of kidney after irradiation.

Different doses of irradiation were performed in which group 1 (non-irradiated), group 2 (8 Gy/single dose/whole body) and group 3 (15 Gy/single dose/whole body) were formed of guinea pigs. After 24 hr of radiation exposure the levels of lipid peroxidation product, malondialdehyde, (MDA), glutathione (GSH) and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured in the whole kidney. The MDA content increased in animals irradiated with 8 and 15 Gy. And group 3 showed an increase the level of MDA. GSH contents of kidney in group 2 and 3 increased. The activity of SOD decreased markedly in group 3 when compared with control group. The activity of GSH-Px decreased significantly in group 2 and group 3 in comparison to controls. It may be concluded that a high dose of ionizing irradiation cause excessive oxidative stress in kidney.

Effect of 24-epibrassinolide on pollen viability during heat-stress in tomato.

Tomato pollen when treated with 24-epibrassinolide (EBR), it was observed that in vitro pollen germination was more tolerant to high temperature. A significantly higher in vitro pollen germination, enhanced tube growth and low pollen bursting were observed in presence of EBR at 35 degrees C. Since a preconditioning treatment of tomato plant was not required for these effects, it is concluded that EBR treatment increased basic thermotolerance of germinating pollen. This study provided the first evidence for EBR induced thermotolerance in germinating pollen.

Proteomic analysis of the cellular proteins induced by adaptive concentrations of hydrogen peroxide in human U937 cells

When cells are first exposed to low levels of oxidative stress, they develop a resistance to a subsequent challenge of the same stress, even at higher levels. Although some protein(s) induced by oxidative stress likely mediated this adaptive response, the nature of these proteins is unknown. In this study, the total proteins extracted from human U937 leukemia cells exposed to 50 mM H2O2 for 24 h to induce an optimal protective response were analyzed by two-dimensional polyacrylamide gel electrophoresis. H2O2 treatment induced elevation of level of 34 protein spots. An analysis of these spots by a matrix associated laser desorption/ionization time-of-flight mass spectrometry identified 28 of the H2O2-induced proteins. These include proteins involved in energy metabolism, translation and RNA processing, chaperoning or mediating protein folding, cellular signaling, and redox regulation, as well as a mitochondrial channel component, and an actin-bundling protein. Therefore, it appears that the cellular adaptation to oxidative stress is a complex process, and is accompanied by a modulation of diverse cellular functions.

Effect of intramuscular norethisterone enanthate on compensatory ovarian hypertrophy in the rat.

Norethisterone enanthate (N.E.) administered in repeated intramuscular doses was found to bring about by and large a dose-related inhibition of compensatory ovarian hypertrophy (COH) which follows after the surgical removal of one ovary in adult rats. The relative inhibition in the responsiveness of the remaining ovary to compensatory gonadotrophic stimulation leading to the COH was of the order of 14.2, 19.0, 26.3, 25.0 and 42.0% with 0.25, 0.50, 1.0, 2.0 and 4.0 mg doses of N.E., respectively. The ED50 was calculated to be of the order of 7.0 mg. There was no effect of the treatment on the weight of the pituitary at any dose, whatsoever. However, the treatment was found to induce a significant increase in the weight of the uterus and the adrenals at higher doses (2.0 and 4.0 mg). The possibility of delineating the antigonadotrophic activity of activity of 'N.E.' from its contraceptive potential, vis-a-vis the dose employed, is discussed.