The objective of the present experiment was to assess the involvement of small intestine in expression of susceptibility or resistance to the high-fat/high-energy diet. The investigation was carried out in adult male Sprague-Dawley rats fed either standard laboratory diet (3.2 kcal/g, 9.5 % fat) or high-fat (HF) diet (4.04 kcal/g, 30 % fat) for 4 weeks as well as in HF rats that were retrospectively designated on the bases of their higher or lower weight gain as sensitive (DIO) or resistant (DR) to obesity. Our results revealed in HF group significant increase in energy intake, food efficiency, weight gain and Lee´s index of obesity. Moreover, in comparison with controls, a significantly increased duodenal and jejunal alkaline phosphatase (AP) and α-glucosidase activity as well as hypertrophy of jejunal mucosa (increased protein/DNA ratio) were observed in HF fed rats. In contrast, intestinal function was inversely related to energy intake or to the development of adiposity in DIO vs. DR rats. The DR rats had significantly greater AP and α-glucosidase activity and more pronounced suppression of energy intake than obese DIO rats. It indicates that the increase of enzyme activities and the lowered effectiveness of nutrient absorption might be a significant factor preventing the expression of obesity proneness. This information contributes to a better understanding of a complex interaction between HF diet feeding and small intestinal adaptability, which determines the energy homeostasis and predict the ability to resist or develop obesity in these phenotypes., Z. Šefčíková, T. Hájek, Ľ. Lenhardt, Ľ. Raček, Š. Možeš., and Obsahuje bibliografii a bibliografické odkazy
Carbonic anhydrase (CA) catalyzes reversible hydration of CO2 and it can compensate for the lack of H2O and CO2 in plants under stress conditions. Antioxidative enzymes play a key role in scavenging reactive oxygen species and in protecting plant cells against toxic effects. Tomato represents a stress-sensitive plant while violet orychophragmus belongs to adversity-resistant plants. In order to study the drought responses in tomato and violet orychophragmus plants, CA and antioxidative enzyme activities, photosynthetic capacity, and water potential were determined in plants under drought stress. We found that there were similar change trends in CA activity and drought tolerance in violet orychophragmus, and in antioxidative enzymes and drought tolerance in tomato plants. Basic mechanisms of drought resistance should be identified for understanding of breeding measures in plants under stress conditions., W. H. Sun, Y. Y. Wu, X. Y. Wen, S. J. Xiong, H. G. He, Y. Wang, G. Q. Lu., and Obsahuje seznam literatury
This work aimed to study the effects of commercial doses of the fungicide, Mancozeb, on the photosynthetic apparatus of lettuce young leaves (YL) and expanded leaves (EL). Seven days after Mancozeb application, chlorophyll a fluorescence, pigment contents, lipid peroxidation, and proline content were evaluated. Independently of leaf age, Mancozeb treatment reduced the efficiency of photosystem II photochemistry, increased the nonphotochemical quenching and proline content, decreased pigment contents, and induced lipid peroxidation. Moreover, EL showed a more stable photosynthetic apparatus, less prone to oxidative damages compared with YL. The parameters measured proved to be good markers for the rapid and preliminary diagnosis of fungicide toxicity., M. C. Dias, P. Figueiredo, I. F. Duarte, A. M. Gil, C. Santos., and Obsahuje bibliografii
Objective of this study was to characterize osmotically-induced insulin secretion in two tumor cell lines. We compared response of freshly isolated rat pancreatic islets and INS-1 and INS-1E tumor cell lines to high glucose, 30 % hypotonic medium and 20 % hypertonic medium. In Ca2+-containing medium glucose induced insulin release in all three cell types. Hypotonicity induced insulin secretion from islets and INS-1 cells but not from INS-1E cells, in which secretion was inhibited despite similar increase in cell volume in both cell types. GdCl3 (100 μmol/l) did not affect insulin response from INS-1E cells to hypotonic challenge. Hypertonic medium inhibited glucose-induced insulin secretion from islets but not from tumor cells. Noradrenaline (1 μmol/l) inhibited glucose-induced but not swelling-induced insulin secretion from INS-1 cells. Surprisingly, perifusion with Ca2+-depleted medium showed distinct secretory response of INS-1E cells to hypotonicity while that of INS-1 cells was partially inhibited. Functioning glucose-induced insulin secretion is not sufficient prerequisite for hypotonicity-induced response in INS-1E cells suggesting that swelling-induced exocytosis is not essential step in the mechanism mediating glucose-induced insulin secretion. Both cell lines are resistant to inhibitory effect of hyperosmolarity on glucose-induced insulin secretion. Response of INS-1E cells to hypotonicity is inhibited by the presence of Ca2+ in medium., M. Orečná, R. Hafko, Z. Bačová, J. Podskočová, D. Chorvát Jr., V. Štrbák., and Obsahuje bibliografii a bibliografické odkazy
The pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae), is a well-studied species in terms of its colour polymorphism, where it occurs as two distinct colour morphs, red and green. It is proposed that the occurrence and maintenance of this polymorphism is an adaptive response to environmental factors, in particular natural enemies and host plant quality. We hypothesized that these adaptations are directly mirrored in the energy reserves accumulated by the different colour morphs during their pre-adult stages and reflect their specialization for particular ecological roles. We quantitatively measured the different energy reserves of red and green pea aphids and found that the total energy reserves of these morphs did not differ. Interestingly, these reserves were made up of different components in the red and green colour morphs. There was a higher percentage content of water-soluble carbohydrates and lipids in the red clones and higher percentage content of protein in green clones. These finding are in accordance with green clones being more fecund than red ones and needing more protein for reproduction than red clones, which produce more winged offspring when crowded or in response to the presence of natural enemies and so, need more lipids and carbohydrates to fuel their walking and flight. Apparently, different colour morphs are physiologically specialized to adjust their energy reserves in relation to their specific ecological adaptations and maximize their fitness in terms of dispersal, reproduction, defense and survival., Seyed Mohammad Ahsaei ... []., and Obsahuje seznam literatury
Responses of the photosynthetic electron transport system of chloroplasts to exogenous proline application were evaluated in young and mature leaves of Arabidopsis thaliana plants under optimal growth conditions. Exogenous proline application (10 mM) during the 4th week of growth increased proline accumulation in young leaves more than in mature leaves, and possibly due to its degradation producing NADPH, decreased significantly the ratio of NADP+/NADPH in both leaf types compared with controls (without proline). However, the ratio of NADP+/NADPH remained significantly higher in the young leaves, suggesting lower proline degradation which resulted in less reduced plastoquinone pool than that in the mature leaves, under both low light [130 μmol(photon) m-2 s-1] and high light [1,200 μmol(photon) m-2 s-1] treatments. The young leaves seemed to adjust nonphotochemical fluorescence quenching in order to maintain a better PSII quantum yield. We concluded that under optimal growth conditions exogenous proline results in overreduction of the plastoquinone pool and blockage of photosynthetic electron flow due to accumulation of NADPH. We suggest that optimum concentrations of proline are required for optimal PSII photochemistry., I. Sperdouli, M. Moustakas., and Obsahuje seznam literatury
Acetylcholinesterase (AChE) inhibitors represent standard treatment of Alzheimer´s disease. Cholesterol plays an important role in Alzheimer´s disease development. Because cholesterol synthesis may be inhibited by statins or bisphosphonates, we hypothesized that these drugs might possibly have an influence on cholinesterases. Moreover, we also evaluated if the cholesterol-lowering agents that cross the blood-brain barrier (e.g. simvastatin) should be more effective than those which do not (e.g. atorvastatin). Four groups of rats were orally administered simvastatin, atorvastatin, alendronate or vehicle for seven days. Thereafter, blood samples were taken and the basal ganglia, septum, frontal cortex, and hippocampus were isolated from brains for measurement of acetylcholinesterase activity. In the blood, activities of neither acetyl- nor butyrylcholinesterase were influenced by any of the applied drugs. In the brain, no significant changes in AChE activity were observed after administration of atorvastatin. Both simvastatin and alendronate significantly suppressed the activity of AChE in the frontal cortex. In conclusion, our results confirmed the hypothesis that cholesterol-modifying drugs modulate AChE activity and it is more reasonable to use a blood-brain barrier penetrating drug., Ľ. Cibičková, V. Palička, N. Cibiček, E. Čermáková, S. Mičuda, L. Bartošová, D. Jun., and Obsahuje bibliografii a bibliografické odkazy
Nostoc muscorum cells showed metal-induced decrease in the relative growth, pigment contents, O2 evolution, and Hill activity in response to lead (Pb2+) and cadmium (Cd2+) treatment, which was further accentuated with increase in metal exposure time and metal concentration. I50 concentrations (50% growth inhibitory concentrations) of Pb2+ and Cd2+ for growth of N. muscorum were 55 and 21 μg mL-1, respectively. These results indicated that the cells of N. muscorum were more susceptible to Cd2+ in comparison to Pb2+. The O2 production was relatively more sensitive to both heavy metals (I50: 16 and 10 μg mL-1 of Pb2+ and Cd2+, respectively) than the Hill activity (I50: 61 and 39 μg mL-1 of Pb2+ and Cd2+, respectively). Further, measurement of Hill activity in the presence of metals and electron donors showed that inhibition sites of both Pb2+ and Cd2+ were located on the oxidizing site of PSII. The chlorophyll a (Chl a) and phycobilisome (PB) fluorescence emission spectra showed that energy transfer from Chl a and PB to PSII reaction center was more susceptible to Cd2+ than Pb2+., S. Dixit, D. P. Singh., and Obsahuje bibliografii
Ischemia can contribute to the inner ear pathology and hearing loss. To determine the susceptibility of inner and outer hair cells (IHCs/OHCs) to ischemic and post-ischemic period, we used organotypic cultures of the organ of Corti isolated from P3 rats as an in vitro model of inner ear ischemia (oxygen-glucose deprivation, OGD). We identified the hair cells (HCs) by phalloidin staining. The cells with damaged cellular membrane integrity were identified by propidium iodide (PI)-exclusion assay. The cells with fragmented chromosomal DNA were detected by TUNEL assay. Organotypic cultures were subjected to a mild (3 h duration) or severe (4 h duration ) OGD, followed by a recovery period of 21 h and 20 h, respectively. Mild OGD induced a loss of 10-20 % HCs, whereas severe OGD induced loss of 35 % HCs. We confirmed that OHCs are less vulnerable to OGD than IHCs. Of all missing OHCs, 80-90 % was lost during the OGD period and 10-20 % during the recovery period. In contrast, the loss of IHCs was equal during both experimental periods. The OGD period was mainly associated with PI-positive nuclei. TUNEL-positive nuclei were a minor frac tion during the OGD period and increased during the recovery period, indicating the progression of DNA fragmentation. Our results implicate a differential susceptibility of IHCs and OHCs during and after ischemia-like insult, which may be of therapeutic consequence., N. Amarjargal ... [et al.]., and Obsahuje seznam literatury
In eukaryotic oxygenic photosynthetic organisms (both plants and algae), the maximum fluorescence is at peak P, with peak M lying much lower, or being even absent. Thus, the PSMT phase, where S is semisteady state, and T is terminal state, is replaced by a monotonous P→T fluorescence decay. In the present study, we found that dimethoate-treated wheat plant leaves showed SM transient, whereas in the case of control plants monotonous P→T fluorescence decay occured. We suggest that this was partly due to quenching of fluorescence due to [H+], responsible for P to S (T) decay in control plants (Briantais et al. 1979) being replaced by state transition (state 2 to state 1) in dimethoate-treated plants (Kaňa et al. 2012)., J. K. Pandey, R. Gopal., and Obsahuje bibliografii