Energy Conservation Mechanism Research Articles

Expression, purification and spectroscopic analysis of an HdrC: An iron–sulfur cluster-containing protein from Acidithiobacillus ferrooxidans

Iron–sulfur cluster-containing proteins are present in all living organisms and are considered to be very ancient due to their ubiquity on the three domains of life, their importance in anaerobic metabolic pathways and energy conservation mechanisms. To date, there is little information regarding these proteins in Acidithiobacillus ferrooxidans, a bacterium involved in bioleaching processes. In this study are described the cloning, expression, purification and spectroscopic characterization of a new Fe–S cluster-containing protein, a putative HdrC homologue, from A. ferrooxidans strain LR. The oligomeric state of the protein was assessed by both dynamic light scattering and size-exclusion chromatography, demonstrating that it is present as a monomer in solution. Far-UV CD measurements revealed that this protein is extremely stable at acidic pHs, in which it assumes a different structure that exhibits a predominance of α-helixes. In contrast, at basic pHs, from 9 to 12, the protein showed a spectral profile which is characteristic for proteins with high content of beta structure and random coil. Thermal unfolding studies demonstrated that this protein tolerates high temperatures at acidic conditions, with a melting temperature of 95°C. Furthermore, bioinformatics analysis suggested a heterodisulfide reductase function for the analyzed protein and for the other identified subunits, HdrA and HdrB, which could be related to hydrogen and/or formate metabolism in A. ferrooxidans.

ENERGY PERFORMANCE IN A FLOOR HEATING SYSTEM OF THERMAL ENERGY STORAGE, USING SOLAR DIRECT GAIN AND AIR SOURCE HEAT PUMP

The authors have built a small test cabin to promote utilization of solar heat energy and have been conducting measurements of temperature, solar radiation, heat flow, electric power and so forth in the cabin. Four important elements were introduced into the cabin in order to make high energy performance and enough thermal comfort. Namely, there are highly insulated envelope, much solar direct gain, a floor heating system including PCM packages for thermal storage and air source heat pump in the cabin. The paper describes outline of specifications for the test cabin and mechanism for energy conservation in the test cabin. It also shows results of verification relating to solar radiation. Good agreement is obtained between calculation and measurement in each of the three phases of solar radiation flow. Behaviors of the floor heating system including the PCM and the heat pump will be followed in the next paper.

An Improved Multi-objective PSO Algorithm with Swarm Energy Conservation

An improved algorithm—multi-objective particle swarm optimization with swarm energy conservation (SEC-MOPSO) is proposed, which is aimed to solve the problem of convergence and distribution in multi-objective particle swarm optimization (MOPSO) algorithm. Swarm energy conservation mechanism is used to update the velocity and position of particles. Besides, non-dominated sorting method, adaptive grid mechanism and elitism mechanism are also incorporated into SEC-MOPSO algorithm to improve searching capabilities and avoid falling into the second-best non-dominated front. The simulation results show that SEC-MOPSO has better performance than MOPSO in distribution and convergence.

Diet and tumor LKB1 expression interact to determine sensitivity to anti-neoplastic effects of metformin in vivo

Hypothesis-generating epidemiological research has suggested that cancer burden is reduced in diabetics treated with metformin and experimental work has raised questions regarding the role of direct adenosine monophosphate-activated protein kinase (AMPK)-mediated anti-neoplastic effects of metformin as compared with indirect effects attributable to reductions in circulating insulin levels in the host. We treated both tumor LKB1 expression and host diet as variables, and observed that metformin inhibited tumor growth and reduced insulin receptor activation in tumors of mice with diet-induced hyperinsulinemia, independent of tumor LKB1 expression. In the absence of hyperinsulinemia, metformin inhibited only the growth of tumors transfected with short hairpin RNA against LKB1, a finding attributable neither to an effect on host insulin level nor to activation of AMPK within the tumor. Further investigation in vitro showed that cells with reduced LKB1 expression are more sensitive to metformin-induced adenosine triphosphate depletion owing to impaired ability to activate LKB1-AMPK-dependent energy-conservation mechanisms. Thus, loss of function of LKB1 can accelerate proliferation in contexts where it functions as a tumor suppressor, but can also sensitize cells to metformin. These findings predict that any clinical utility of metformin or similar compounds in oncology will be restricted to subpopulations defined by host insulin levels and/or loss of function of LKB1.

How to Make a Living by Exhaling Methane

Methane produced in the biosphere is derived from two major pathways. Conversion of the methyl group of acetate to CH(4) in the aceticlastic pathway accounts for at least two-thirds, and reduction of CO(2) with electrons derived from H(2), formate, or CO accounts for approximately one-third. Although both pathways have terminal steps in common, they diverge considerably in the initial steps and energy conservation mechanisms. Steps and enzymes unique to the CO(2) reduction pathway are confined to methanogens and the domain Archaea. On the other hand, steps and enzymes unique to the aceticlastic pathway are widely distributed in the domain Bacteria, the understanding of which has contributed to a broader understanding of prokaryotic biology.

Bacterial Na + -translocating ferredoxin:NAD + oxidoreductase

The anaerobic acetogenic bacterium Acetobacterium woodii carries out a unique type of Na(+)-motive, anaerobic respiration with caffeate as electron acceptor, termed "caffeate respiration." Central, and so far the only identified membrane-bound reaction in this respiration pathway, is a ferredoxin:NAD(+) oxidoreductase (Fno) activity. Here we show that inverted membrane vesicles of A. woodii couple electron transfer from reduced ferredoxin to NAD(+) with the transport of Na(+) from the outside into the lumen of the vesicles. Na(+) transport was electrogenic, and accumulation was inhibited by sodium ionophores but not protonophores, demonstrating a direct coupling of Fno activity to Na(+) transport. Results from inhibitor studies are consistent with the hypothesis that Fno activity coupled to Na(+) translocation is catalyzed by the Rnf complex, a membrane-bound, iron-sulfur and flavin-containing electron transport complex encoded by many bacterial and some archaeal genomes. Fno is a unique type of primary Na(+) pump and represents an early evolutionary mechanism of energy conservation that expands the redox range known to support life. In addition, it explains the lifestyle of many anaerobic bacteria and gives a mechanistic explanation for the enigma of the energetic driving force for the endergonic reduction of ferredoxin with NADH plus H(+) as reductant in a number of aerobic bacteria.

Study on Government Management Mechanism of Energy Conservation and Emission Reduction

Energy conservation and emission reduction is essential to suitable development and economic development in harmony with the environment. Building the government management mechanism of energy conservation and emission reduction has become an important task of government reforms. Study the retraining factors of energy conservation and emission reduction, and propose legal guarantees, management innovation, technology innovation, service system construction and upgrading of industrial structure are the critical factors to energy conservation and emission reduction management mechanism‘s performance. Then discuss the critical factors deeply. Improve the special legislation, department law linkage and strengthening law enforcement supervision are essential to providing legal guarantees for energy conservation and emission reduction; comprehensive evaluation system and strict control system are essential to management innovation; policy guide and comprehensive utilization is essential to technology innovation; positive policy guide for development of consultation industry is the main task of energy conservation and emission reduction service system construction; high and new technology industries, elimination of outdated production capacity and development of recycling economy are useful for upgrading of industrial structure.

A tier-based asynchronous scheduling scheme for delay constrained energy efficient connectivity in asymmetrical wireless devices

Effective energy conservation scheme should support the asymmetrical nature of wireless devices like capacity limitations and signal strength in an efficient end-to-end connectivity manner. Prolonging network lifetime has a major impact on the network and on the energy consumption of each device individually. This work considers an approach in which on a dissimilar-based schedules, the interfaces change their state in which the energy conservation mechanism takes place. The proposed model takes into account metrics like the signal strength and devices’ capacity limitations, and encompasses them into the layered asynchronous scheduling scheme for providing end-to-end reliability and performance measures extraction. This work mainly proposes an association for controlling the power consumption parameters into a bounded limit and within a range of bounded values, measuring at the same time the critical transmitting range of each device. Through the designed two-tier architecture and layering approach, and through the experimental simulation, the proposed energy-aware management scheme is thoroughly evaluated in order to limit these parameters in terms of traffic density, storage measurements and the impact of caching on each device, into the desired values.

Thermodynamic analysis of the theoretical energy consumption in the removal of organic contaminants by physical methods

The essential requirements for evaluating the sustainable development of a system and the thermodynamic framework of the energy conservation mechanism in the waste-removal process are proposed. A thermodynamic method of analysis based on the first and second laws of thermodynamics is suggested as a means to analyze the theoretical energy consumption for the removal of organic contaminants by physical methods. Moreover, the theoretical energy consumption for the removal by physical methods of different kinds of representative organic contaminants with different initial concentrations and amounts is investigated at 298.15 K and 1.01325 × 105 Pa. The results show that the waste treatment process has a high energy consumption and that the theoretical energy consumption for the removal of organic contaminants increases with the decrease of their initial concentrations in aqueous solutions. The theoretical energy consumption for the removal of different organic contaminants varies dramatically. Furthermore, the theoretical energy consumption increases greatly with the increase in the amount to be removed.

Three-dimensional musculoskeletal kinematics during bipedal locomotion in the Japanese macaque, reconstructed based on an anatomical model-matching method

Studying the bipedal locomotion of non-human primates is important for clarifying the evolution of habitual bipedalism in the human lineage. However, quantitative descriptions of three-dimensional kinematics of bipedal locomotion in non-human primates are very scarce, due to difficulties associated with measurements. In this study, we performed a kinematic analysis of bipedal locomotion on two highly trained (performing) Japanese macaques walking on a treadmill at different speeds and estimated three-dimensional angular motions of hindlimb and trunk segments, based on a model-based registration method. Our results demonstrated a considerable degree of axial rotation occurring at the trunk and hip joints during bipedal locomotion, suggesting that bipedal locomotion in Japanese macaques is essentially three-dimensional. In addition, ranges of angular motions at the hip and ankle joints were larger and the knee joint was more flexed in the mid-stance phase with increasing speed, indicating that gait kinematics are modulated depending on speed. Furthermore, macaques were confirmed to have actually acquired, at least to some extent, the energy conservation mechanism of walking due to pendular exchange of potential and kinetic energy, but effective utilization of this mutual exchange of energy was found to occur only at comparatively low velocity. Spring-like running mechanics were probably more exploited at higher speed because the duty factor was above 0.5. Fundamental differences in bipedal strategy seem to exist between human and non-human primate bipedal locomotion.

Hepatic mitochondrial energetics during catch-up fat after caloric restriction

The objective of the study was to investigate whether changes in liver mitochondrial energetics could underlie the enhanced energetic efficiency that drives accelerated body fat recovery (catch-up fat) during refeeding after caloric restriction. Rats were subjected to caloric restriction (50% of ad libitum intake) for 15 days and then refed for 1 or 2 weeks on an amount of chow equal to that of controls matched for weight at the onset of refeeding. Whole-body metabolism was characterized by energy balance and body composition determinations as well as by indirect calorimetric measurements of 24-hour energy expenditure, substrate oxidation, and whole-body de novo lipogenesis estimated from nonprotein respiratory quotient. Hepatic mitochondrial energetics were determined from measurements of liver mitochondrial mass, respiratory capacities, and proton leak (both basal and fatty acid stimulated), whereas hepatic oxidative status was assessed from measurements of hepatic mitochondrial lipid peroxidation, aconitase, and superoxide dismutase activity. Furthermore, hepatic lipogenic capacity was determined from assays of fatty acid synthase activity. Compared with controls, isocalorically refed rats showed an elevated energetic efficiency and body fat gain over both week 1 and week 2 of refeeding, as well as a lower 24-hour energy expenditure and higher rates of whole-body de novo lipogenesis at the end of both week 1 and week 2 of refeeding. Analysis of the liver revealed that after 1 week (but not after 2 weeks) of refeeding, the mitochondrial mass (but not mitochondrial density) was lower in refed rats than in controls, associated with higher state 3 mitochondrial respiratory capacity, increased superoxide dismutase activity, as well as higher fatty acid synthase activity. These results suggest that, although at the whole-body level elevations in energy efficiency and de novo lipogenesis are coordinated toward catch-up fat, the overall hepatic mitochondrial energetic status during refeeding is more consistent with a contributory role of the liver in the enhanced de novo lipogenic machinery during catch-up fat rather than in the energy-conservation mechanisms (elevated energetic efficiency) that spare energy for catch-up fat.

Effect of Food Restriction on Energy Expenditure of Monosodium Glutamate-Induced Obese Rats

The neonatal administration of monosodium glutamate (MSG) to rodents leads to obesity in the adult animal, characterized by increased fat storages. Chronic food restriction is known to induce reduction in body energy expenditure, as an adaptive mechanism to save energy. Our purpose was to examine whether obesity can alter the mechanism of energy conservation in food-restricted animals. Newborn female Wistar rats were injected either MSG (obese) or saline (control). At the age of 90 days, the animals were fed daily ad libitum (control and MSG) or restricted (50%) (control-restricted and MSG-restricted). After 30 days the animals were sacrificed and the energy balance was determined by calorimetric analysis. Some parameters of energy balance and body composition were affected by MSG treatment as well as food restriction. The percent reduction of the energy expenditure and fat content in MSG-restricted animals was lower than control-restricted animals, when compared with their respective ad libitum groups. These results indicate that all food-restricted animals were able to develop the mechanism of energy conservation, regardless of the obesity, but it was less efficient in MSG-obese animals.

Gene expression profiling of the short-term adaptive response to acute caloric restriction in liver and adipose tissues of pigs differing in feed efficiency

Residual feed intake (RFI) is a measure of feed efficiency, in which low RFI denotes improved feed efficiency. Caloric restriction (CR) is associated with feed efficiency in livestock species and to human health benefits, such as longevity and cancer prevention. We have developed pig lines that differ in RFI, and we are interested in identifying the genes and pathways that underlie feed efficiency. Prepubertal Yorkshire gilts with low RFI (n = 10) or high RFI (n = 10) were fed ad libitum or fed at restricted intake of 80% of maintenance energy requirements for 8 days. We measured serum metabolites and hormones and generated transcriptional profiles of liver and subcutaneous adipose tissue on these animals. Overall, 6,114 genes in fat and 305 genes in liver were differentially expressed (DE) in response to CR, and 311 genes in fat and 147 genes in liver were DE due to RFI differences. Pathway analyses of CR-induced DE genes indicated a dramatic switch to a conservation mode of energy usage by down-regulating lipogenesis and steroidogenesis in both liver and fat. Interestingly, CR altered expression of genes in immune and cell cycle/apoptotic pathways in fat, which may explain part of the CR-driven lifespan enhancement. In silico analysis of transcription factors revealed ESR1 as a putative regulator of the adaptive response to CR, as several targets of ESR1 in our DE fat genes were annotated as cell cycle/apoptosis genes. The lipid metabolic pathway was overrepresented by down-regulated genes due to both CR and low RFI. We propose a common energy conservation mechanism, which may be controlled by PPARA, PPARG, and/or CREB in both CR and feed-efficient pigs.

Ecophysiology of neuronal metabolism in transiently oxygen-depleted environments: Evidence that GABA is accumulated pre-synaptically in the cerebellum

Interactions between coral reef topography, tide cycles, and photoperiod provided selection pressure for adaptive physiological changes in sheltered hypoxic niches to be exploited by specialized tropical reef fish. The epaulette shark Hemiscyllium ocellatum withstands cyclic hypoxia in its natural environment, many hours of experimental hypoxia, and anoxia for up to 5 h. It shows neuronal hypometabolism in response to 5% oxygen saturation. Northern-hemisphere hypoxia- and anoxia-tolerant vertebrates that over-winter under ice alter their inhibitory to excitatory neurotransmitter balance to forestall brain ATP depletion in the absence of oxidative phosphorylation. GABA immunochemistry, HPLC analysis and receptor binding studies in H. ocellatum cerebellum revealed a heterogeneous regional accumulation of neuronal GABA despite no change in its overall concentration, and a significant increase in GABA A receptor density without altered binding affinity. Increased GABA A receptor density would protect the cerebellum during reoxygenation when transmitter release resumes. While all hypoxia- and anoxia-tolerant teleosts examined to date respond to low oxygen levels by elevating brain GABA, the phylogenetically older epaulette shark did not, suggesting that it uses an alternative neuroprotective mechanism for energy conservation. This may reflect an inherent phylogenetic difference, or represent a novel ecophysiological adaptation to cyclic variations in the availability of oxygen.

Biochemistry and molecular biology of lithotrophic sulfur oxidation by taxonomically and ecologically diverse bacteria and archaea

Lithotrophic sulfur oxidation is an ancient metabolic process. Ecologically and taxonomically diverged prokaryotes have differential abilities to utilize different reduced sulfur compounds as lithotrophic substrates. Different phototrophic or chemotrophic species use different enzymes, pathways and mechanisms of electron transport and energy conservation for the oxidation of any given substrate. While the mechanisms of sulfur oxidation in obligately chemolithotrophic bacteria, predominantly belonging to Beta- (e.g. Thiobacillus) and Gammaproteobacteria (e.g. Thiomicrospira), are not well established, the Sox system is the central pathway in the facultative bacteria from Alphaproteobacteria (e.g. Paracoccus). Interestingly, photolithotrophs such as Rhodovulum belonging to Alphaproteobacteria also use the Sox system, whereas those from Chromatiaceae and Chlorobi use a truncated Sox complex alongside reverse-acting sulfate-reducing systems. Certain chemotrophic magnetotactic Alphaproteobacteria allegedly utilize such a combined mechanism. Sulfur-chemolithotrophic metabolism in Archaea, largely restricted to Sulfolobales, is distinct from those in Bacteria. Phylogenetic and biomolecular fossil data suggest that the ubiquity of sox genes could be due to horizontal transfer, and coupled sulfate reduction/sulfide oxidation pathways, originating in planktonic ancestors of Chromatiaceae or Chlorobi, could be ancestral to all sulfur-lithotrophic processes. However, the possibility that chemolithotrophy, originating in deep sea, is the actual ancestral form of sulfur oxidation cannot be ruled out.

Food availability as a cue for mechanisms of winter energy conservation in red deer

Food availability as a cue for mechanisms of winter energy conservation in red deer

Genetic, immunological and biochemical evidence for a Rnf complex in the acetogen Acetobacterium woodii

Acetogenic bacteria grow by the oxidation of various substrates coupled to the reduction of carbon dioxide (acetogenesis) or other electron acceptors but the mechanisms of energy conservation are still enigmatic. Here, we report the presence of a rnf gene cluster rnfCDGEAB in Acetobacterium woodii that is speculated to encode a novel, energy-conserving ferredoxin:NAD(+)-oxidoreductase complex composed of at least six different subunits. Transcriptional analysis revealed that the genes constitute an operon. RnfC and RnfG were heterologously produced and antibodies were generated. Western blot analyses demonstrated that these subunits were produced and are associated with the cytoplasmic membrane. The subunits were present in cells respiring with either carbon dioxide or caffeate. A preparation with NADH dehydrogenase activity was obtained from detergent solubilized membranes that contained RnfC and RnfG.

Comparative Analysis of Energy-Saving Techniques in 3GPP and 3GPP2 Systems

Energy conservation is essential to wireless networks, particularly for third-generation (3G) and fourth-generation (4G) wireless systems, because high-speed data transmissions would rapidly exhaust the energy of a mobile station. This paper presents the details of energy-saving mechanisms for packet data services in two major standards, namely, the Third-Generation Partnership Project (3GPP) and the Third-Generation Partnership Project 2 (3GPP2). In addition to qualitative comparison, analytic models and quantitative comparison based on the energy-saving models are provided. The proposed analytic models analyze and quantify the energy consumption for bursty and streaming traffic in cdma2000 and wideband code division multiple access (WCDMA). The impacts of an inactivity timer on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">energy</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">consumption</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">and</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reconnection</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cost</i> are demonstrated further by simulation and analysis. The analytic results could be used to suggest proper timer lengths that can balance the energy consumption and the reconnection cost. In addition to providing insights of the energy-conservation mechanisms of 3GPP and 3GPP2, which are often difficult to directly obtain from standards specifications, results shown in this paper are also practical for 3GPP and 3GPP2 operators to determine proper parameters for energy efficiency.

Proteomic analysis of Aspergillus nidulans cultured under hypoxic conditions

The fungus Aspergillus nidulans reduces nitrate to ammonium and simultaneously oxidizes ethanol to acetate to generate ATP under hypoxic conditions in a mechanism called ammonia fermentation (Takasaki, K. et al.. J. Biol. Chem. 2004, 279, 12414-12420). To elucidate the mechanism, the fungus was cultured under normoxic and hypoxic (ammonia fermenting) conditions, intracellular proteins were resolved by 2-DE, and 332 protein spots were identified using MALDI MS after tryptic digestion. Alcohol and aldehyde dehydrogenases that play key roles in oxidizing ethanol were produced at the basal level under hypoxic conditions but were obviously provoked by ethanol under normoxic conditions. Enzymes involved in gluconeogenesis, as well as the tricarboxylic and glyoxylate cycles, were downregulated. These results indicate that the mechanism of fungal energy conservation is altered under hypoxic conditions. The results also showed that proteins in the pentose phosphate pathway as well as the metabolism of both nucleotide and thiamine were upregulated under hypoxic conditions. Levels of xanthine and hypoxanthine, deamination products of guanine and adenine were increased in DNA from hypoxic cells, indicating an association between hypoxia and intracellular DNA base damage. This study is the first proteomic comparison of the hypoxic responses of A. nidulans.

Modeling of Contaminant Transport in Underground Coal Gasification

In order to study and discuss the impact of contaminants produced from underground coal gasification on groundwater, a coupled seepage-thermodynamics-transport model for underground gasification was developed on the basis of mass and energy conservation and pollutant-transport mechanisms, the mathematical model was solved by the upstream weighted multisell balance method, and the model was calibrated and verified against the experimental site data. The experiment showed that because of the effects of temperature on the surrounding rock of the gasification panel the measured pore-water-pressure was higher than the simulated one; except for in the high temperature zone where the simulation errors of temperature, pore water pressure, and contaminant concentration were relatively high, the simulation values of the overall gasification panel were well fitted with the measured values. As the gasification experiment progressed, the influence range of temperature field expanded, the gradient of groundwater pressure decreased, and the migration velocity of pollutant increased. Eleven months and twenty months after the test, the differences between maximum and minimum water pressure were 2.4 and 1.8 MPa, respectively, and the migration velocities of contaminants were 0.24-0.38 m/d and 0.27-0.46 m/d, respectively. It was concluded that the numerical simulation of the transport process for pollutants from undergroundmore » coal gasification was valid. 42 refs., 13 figs., 1 tab.« less