Seasonal changes in the FA composition of triacylglycerols and phospholipids prepared from the whole bodies of non-diapausing and diapausing fifth instar larvae of Ostrinia nubilalis, Hubn. ...(Lepidoptera: Crambidae) were determined to evaluate the role of these lipids in diapause. Substantial changes in the FA composition of triacylglycerols and phospholipids were triggered by diapause development. This led to a significant increase in the overall FA unsaturation (UFAs/SFAs ratio), attributable to an increase in the relative proportion of MUFAs and the concomitant decrease in PUFAs and SFAs. In triacylglycerols, the significant changes in the FAs composition are the result of an increase in the relative proportions of MUFAs, palmitoleic acid (16:1n-7) and oleic acid (18:1n-9), and a concomitant reduction in the composition of SFAs and PUFAs, mainly palmitic acid (16:0) and linoleic acid (18:2n-6), respectively. Changes in the composition of phospholipids were more subtle with FAs contributing to the overall increase of FA unsaturation. Differential scanning calorimetry (DSC) analysis revealed that the melt transition temperatures of total lipids prepared from whole larvae, primarily attributable to the triacylglycerol component, were significantly lower during the time course of diapause compared with non-diapause. These observations were correlated to the FA composition of triacylglycerols, most likely enabling them to remain functional during colder winter conditions. We conclude that O. nubilalis undergoes remodeling of FA profiles of both energy storage triacylglycerols and membrane phospholipids as an element of its overwintering physiology which may improve the ability to cold harden during diapause.
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•GC–MS sugar/polyol pattern for non- vs. diapausing O. nubilalis larvae was analyzed.•Glycerol, trehalose, sorbitol, mio-inositol, glucose and fructose were identified.•Glycerol and ...trehalose are the most abundant compounds in diapausing larvae.•In mid diapause, cold induced elevated glycerol and reduction of other polyols.•Low temperature increased content of all tested sugars at the end of diapause.
The European corn borer (ECB, Ostrinia nubilalis Hbn.) is a major pest in temperate regions of Europe and North America. Fifth instar ECB larvae enter diapause before winter and gradually develop cold hardiness. Here we investigated the combined influence of diapause phase and low temperature on sugar and polyol content in ECB larvae. Larvae in mid-diapause or diapause termination were acclimated at 5 °C, −3°C or −16 °C, and sugar and polyol content was measured using GC–MS. Control GC–MS measurements were conducted on untreated non-diapausing larvae. We detected differences in polyol (glycerol, sorbitol, myo-inositol) and sugar (trehalose, fructose, glucose) levels in diapausing versus non-diapausing larvae. Glycerol and trehalose were the most abundant of all analyzed cryoprotective compounds in diapausing larvae. Exposure of diapausing larvae to decreasing temperatures induced changes in polyol and sugar levels that depended on the phase of diapause. In mid-diapause larvae, decreasing temperatures induced a significant increase in glycerol and a decrease in sorbitol and myo-inositol. In larvae at diapause termination, polyol content was lower and less influenced by decreasing temperatures. In contrast, sugar levels were lower in larvae at mid-diapause versus diapause termination. Exposure of larvae to −16 °C induced a significant increase in the levels of all detected sugars. In particular, glucose levels were significantly higher in larvae at diapause termination following exposure to −16 °C. We propose that this shift toward sugar synthesis following low temperature exposure in larvae at diapause termination is a consequence of NADPH dependent polyol synthesis, and may be a mechanism for preservation of carbon reserves needed for post-diapause development.
The binding of spin-labeled fatty acids (SLFAs) to the human serum albumin (HSA) examined by electron paramagnetic resonance (EPR) spectroscopy was studied to evaluate the potential of the ...HSA/SLFA/EPR technique as a biomarking tool for cancer. A comparative study was performed on two spin labels with nitroxide groups attached at opposite ends of the fatty acid (FA) chain, 5-doxyl stearic (5-DS) and 16-doxyl stearic (16-DS) acid. The effects of incubation time, different SLFA/HSA molar ratios, ethanol, and temperature showed that the position of the nitroxide group produces certain differences in binding between the two SLFAs. Spectra for different SLFA/HSA molar ratios were decomposed into two spectral components, which correspond to the weakly and strongly bound SLFAs. The reduction of SLFA with ascorbate showed the existence of a two component process, fast and slow, confirming the decomposition results. Warfarin has no effect on the binding of the two SLFAs, whereas ibuprofen significantly decreases the binding of 5-DS and has no effect on 16-DS. Together, the results of this study indicate that both SLFAs, 5-DS and 16-DS, should be used for the study of HSA conformational changes in blood induced by various medical conditions.
This paper presents a novel approach for the simultaneous modelling and forecasting of wind signal components. This is achieved in the complex domain by using novel neural network algorithms and ...architectures. We first perform a signal nonlinearity and component-dependent analyses, which suggest the use of modular complex-valued recurrent neural networks (RNNs). This RNN-based modelling rests upon a combination of nonlinearity, complexity and internal memory and allows for the multiple step ahead forecasting of the wind signal in its complex form (speed and direction). The approach is first verified on benchmark Data Set A (
NH
3
laser data) of the Santa Fe Time Series Prediction Competition together with artificial data generated by chaotic Mackey–Glass equations, and then applied to the real-world wind measurements. Simulations support the proposed architecture and algorithms.
•Hybrid decomposition approach for distribution network planning with DGs is proposed.•Mixed integer linear programming model is designed to minimize total expansion cost.•Simulated annealing ...algorithm is proposed to guide the decomposition and solution process.•Proposed approaches can produce high quality solutions for various size radial distribution networks with DGs.•Failures at DGs have noticeable influence on the selection of the best expansion plan.
This paper presents a hybrid simulated annealing (SA) and mixed integer linear programming (MILP) approach for static expansion planning of radial distribution networks with distributed generators (DGs). The expansion planning problem is first modeled as MILP optimization problem with the goal of minimizing the investment cost, cost of losses, cost of customer interruptions due to failures at the branches and at DGs and the cost of lost DG production due to failures at branches. In order to reduce the complexity of planning problems the decomposition of the original problem is proposed into a number of sequences of sub-problems (local networks) that are solved using the MILP model. The decomposition and solution process is iteratively guided and controlled by the proposed SA algorithm that employs the proper intensification and diversification mechanism to obtain the minimum total cost solution.
A Potential Source of Free Radicals in Iodine-Based Chemical Oscillators Stanisavljev, Dragomir R; Milenković, Maja C; Mojović, Miloš D ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
03/2011, Letnik:
115, Številka:
11
Journal Article
Recenzirano
The iodide−peroxide system in an acidic medium was investigated as a potential source of free radicals in iodine-based chemical oscillators. The radicals were detected by EPR spin-trapping using ...spin-trap 5-(tert-butoxycarbonyl)-5-methyl-1-pyrroline N-oxide (BMPO), which forms stable spin-adducts with oxygen-centered radicals. The iodide−peroxide system is introduced as an easily available laboratory source of free radicals.
Larvae of the European corn borer (
Ostrinia nubilalis
Hubn.) were cold acclimated during different phases of diapause to determine if changes in the fatty acid composition lipids occur as part of a ...programmed diapause strategy, or as a response to low temperatures during winter. Cold acclimation of fifth instar larvae of
O. nubilalis
during diapause had modest effects further on the readjustments in fatty acid composition of triacylglycerols and phospholipids. Overall, FA unsaturation (UFAs/SFAs ratio) was stable, with the exception of the triacylglycerols fraction after exposure to −3 and −10 °C in mid-diapause (MD) when it significantly increased. Differential scanning calorimetry (DSC) was used to examine phase transitions of total body lipid of cold-acclimated larvae in diapause. Thermal analysis indicated that changes in the melt transition temperatures of whole body total lipids were subtle, but consistent with the modest changes in the level of FA unsaturation observed. We conclude that lipid rearrangements are a function of the endogenous “diapause program” rather than a direct effect of low temperatures, which proved to have limited impact on lipid changes in diapausing larvae of
O. nubilalis
.
Oxygen Centered Radicals in Iodine Chemical Oscillators Stanisavljev, Dragomir R; Milenković, Maja C; Mojović, Miloš D ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
07/2011, Letnik:
115, Številka:
27
Journal Article
Recenzirano
The existence of free radicals in iodine-based oscillatory systems has been debated for some time. Recently, we have reported the presence of reactive oxygen species (ROS) in the iodide–peroxide ...system in acidic medium, which is common to all iodine-based oscillatory systems ( J. Phys. Chem. A 2011, 115, 2247−2249 ). In this work, the goal was to identify the ROS produced in this system using an EPR spin trap which can distinguish between hydroxyl (HO•) and hydroperoxyl (HOO•) radicals. The formation of the hydroperoxyl radical was observed and a possible explanation for the low EPR signal of hydroxyl radical was proposed.
In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for ...stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.
Diapause is a state of arrested development during which insects cope with many external and internal stressful factors. European corn borer, Ostrinia nubilalis, overwinters as a fifth instar ...freeze-tolerant diapausing larva. In order to explore diapause-linked stress tolerance processes, the expression of selected genes coding for stress-related proteins—glutathione S-transferase (Gst), thioredoxin (Trx), glutaredoxin (Grx), ferritin (Fer), metallothionein (Mtn), and heat shock proteins Hsp90, Hsc70, Hsp20.4, and Hsp20.1—was assessed in the fat body of diapause-destined, warm (22°C) and cold (5°C) acclimated diapausing larvae using the quantitative real-time PCR. Gene expression was normalised to mRNA transcripts for Actin and Rps03, and relative expression was calculated using non-diapausing larvae as a control group. During the initiation phase of diapause, the abundance of mRNA transcripts of Grx, Hsp90, Hsc70, and Hsp20.1 was significantly upregulated, Trx, Fer, Mtn, and Hsp20.1 were unchanged, while only Gst was clearly downregulated in comparison to non-diapause control. Later, in the early phase of diapause, the expression of most genes (except Trx and Hsp20.1) was upregulated in warm-acclimated larvae, while only Trx and Hsp90 were upregulated in cold-acclimated larvae. Furthermore, the relative expression of all genes (except Trx) increased gradually throughout the diapause in cold-acclimated larvae. This result indicates that the half-life of mRNAs is prolonged during diapause at low temperature, which may lead to a gradual accumulation of mRNA transcripts. Our results show that both diapause programming and temperatures affect the expression of stress-related genes in Ostrinia nubilalis.
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