Mechanism Of Energy Production Research Articles

Polyextremotolerant black fungi: oligotrophism, adaptive potential, and a link to lichen symbioses.

Black meristematic fungi can survive high doses of radiation and are resistant to desiccation. These adaptations help them to colonize harsh oligotrophic habitats, e.g., on the surface and subsurface of rocks. One of their most characteristic stress-resistance mechanisms is the accumulation of melanin in the cell walls. This, production of other protective molecules and a plastic morphology further contribute to ecological flexibility of black fungi. Increased growth rates of some species after exposure to ionizing radiation even suggest yet unknown mechanisms of energy production. Other unusual metabolic strategies may include harvesting UV or visible light or gaining energy by forming facultative lichen-like associations with algae or cyanobacteria. The latter is not entirely surprising, since certain black fungal lineages are phylogenetically related to clades of lichen-forming fungi. Similar to black fungi, lichen-forming fungi are adapted to growth on exposed surfaces with low availability of nutrients. They also efficiently use protective molecules to tolerate frequent periods of extreme stress. Traits shared by both groups of fungi may have been important in facilitating the evolution and radiation of lichen-symbioses.

Homology cloning, sequence characterization, and expression analysis of cDNA encoding electron transfer flavoprotein beta polypeptide in mud crab (Scylla paramamosain)

Electron transfer flavoproteins (ETFs) are αβ-heterodimers found in eukaryotic mitochondria and bacteria. Herein we report a full-length complementary DNA of a mud crab (Scylla paramamosain) ETF β subunit (Scpa-ETFB) isolated with a homology cloning strategy. The complete complementary DNA of the Scpa-ETFB contains a 17-nt 5'-untranslated region, a 765-nt open reading frame encoding 254 amino acids, and a 248-nt 3'-untranslated region. The high identity of Scpa-ETFB with ETFB in other organisms indicated that Scpa-ETFB is a new member of the ETFB family. Although the conserved motif associated with flavin adenine dinucleotide binding is absent in Scpa-ETFB, the signature sequences of the ETF superfamily were identified. Using reverse transcriptase polymerase chain reaction, we detected the messenger RNA transcript of Scpa-ETFB in high levels in the tissues of the hepatopancreas, ovary, heart, and muscle. Phylogenetic analysis showed that Scpa-ETFB is most closely related to the ETFB genes of Caligus rogercresseyi and Lepeophtheirus salmonis. These results provided basic information for elucidating the molecular mechanism of energy production in the mud crab.

The role of metallobiology and amyloid‐β peptides in Alzheimer’s disease

The biggest risk factor for Alzheimer's disease is the process of ageing, but the mechanisms that lead to the manifestation of the disease remain to be elucidated. Why age triggers the disease is unclear but an emerging theme is the inability for a cell to efficiently maintain many key processes such as energy production, repair, and regenerative mechanisms. Metal ions are essential to the metabolic function of every cell. This review will explore the role and reported changes in metal ions in Alzheimer disease, particularly the brain, blood and cerebral spinal fluid, emphasizing how iron, copper and zinc may be involved through the interactions with amyloid precursor protein, the proteolytically cleaved peptide amyloid-beta (Aβ), and other related metalloproteins. Finally, we explore the monomeric makeup of possible Aβ dimers, what a dimeric Aβ species from Alzheimer's disease brain tissue is likely to be composed of, and discuss how metals may influence Aβ production and toxicity via a copper catalyzed dityrosine cross-link.

A schematic model for energy and charge transfer in the chlorophyll complex

A theory for simultaneous charge and energy transfer in the carotenoid-chlorophyll-a complex is presented here and discussed. The observed charge transfer process in these chloroplast complexes is reasonably explained in terms of this theory. In addition, the process leads to a mechanism to drive an electron in a lower to a higher-energy state, thus providing a mechanism for the ejection of the electron to a nearby molecule (chlorophyll) or into the environment. The observed lifetimes of the electronically excited states are in accord/agreement with the investigations of Sundstrom et al. and are in the range of pico-seconds and less. The change in electronic charge distribution in internuclear space as the system undergoes an electronic transition to a higher-energy state could, under appropriate physical conditions, lead to oscillating dipoles capable of transmitting energy from the carotenoid-chlorophylls chromophore to the reaction center by sending an electromagnetic wave (a photon) which provides a novel new mechanism for energy production. In the simplest version of the Forster–Dexter theory, the excitation energy of a donor is transferred to an acceptor and then de-excited to the ground state by fluorescence with no electron being transferred. In the process proposed herein, charge and energy both are transferred from donor to acceptor which can further de-excite by fluorescence. The charge transfer time scale involving an actual transfer of electron is in the pico-second range.

Biochemical rationale and experimental data on the antiaging properties of CoQ10 at skin level

Coenzyme Q(10) (CoQ(10) ) is a key component of the mitochondrial respiratory chain and, therefore, is essential for the bioenergetics of oxidative phosphorylation. It is also endowed with antioxidant properties, and recent studies pointed out its capability of affecting the expression of different genes. In this review, we analyze the data on the mechanisms by which CoQ(10) interacts with skin aging processes. The effect of CoQ(10) in preserving mitochondrial function cooperates in maintaining a proper energy level, which serves to prevent the aging skin from switching to anaerobic energy production mechanisms. Furthermore, the antioxidant capacity of CoQ(10) contributes to a positive effect against UV-mediated oxidative stress. Some of these effects have been assessed also in vivo, by the sensitive technique of ultraweak photoemission. Finally, CoQ(10) has been shown to influence, through a gene induction mechanism, the synthesis of some key proteins of the skin and to decrease the expression of some metalloproteinase such as collagenase. These mechanisms may also contribute to preserve collagen content of the skin.

Mechanism of electric energy production in galvanic and concentration cells

The mechanism of electric energy production in galvanic and concentration cells, which is based on considering the reaction of separate ions, is described. The production electric energy via useful work in concentration and galvanic cells is considered at constant temperature and pressure by analogy to the Van’t Hoff equilibrium box (VHEB) on a molecular level. It is shown that the reaction heat dissipates in a thermostat (or in the environment) and does not participate in electric energy production. The only source of useful work is the thermal thermostat energy (that of the environment). The second law of thermodynamics is satisfied because the useful work arising from cooling of the environment is accompanied by a decrease in the volume of reagents and an increase in the volume of products. Electric energy arises indirectly via heat exchange with a thermostat according to the scheme reaction heat → thermal thermostat energy → useful work → electric energy. Execution of useful work due to thermal thermostat energy provides electric charging of electrodes whose discharging is followed by electric energy release.

2-Deoxy-D-Glucose Treatment Induces Ketogenesis, Sustains Mitochondrial Function, and Reduces Pathology in Female Mouse Model of Alzheimer's Disease

Previously, we demonstrated that mitochondrial bioenergetic deficits preceded Alzheimer's disease (AD) pathology in the female triple-transgenic AD (3xTgAD) mouse model. In parallel, 3xTgAD mice exhibited elevated expression of ketogenic markers, indicating a compensatory mechanism for energy production in brain. This compensatory response to generate an alternative fuel source was temporary and diminished with disease progression. To determine whether this compensatory alternative fuel system could be sustained, we investigated the impact of 2-deoxy-D-glucose (2-DG), a compound known to induce ketogenesis, on bioenergetic function and AD pathology burden in brain. 6-month-old female 3xTgAD mice were fed either a regular diet (AIN-93G) or a diet containing 0.04% 2-DG for 7 weeks. 2-DG diet significantly increased serum ketone body level and brain expression of enzymes required for ketone body metabolism. The 2-DG-induced maintenance of mitochondrial bioenergetics was paralleled by simultaneous reduction in oxidative stress. Further, 2-DG treated mice exhibited a significant reduction of both amyloid precursor protein (APP) and amyloid beta (Aβ) oligomers, which was paralleled by significantly increased α-secretase and decreased γ-secretase expression, indicating that 2-DG induced a shift towards a non-amyloidogenic pathway. In addition, 2-DG increased expression of genes involved in Aβ clearance pathways, degradation, sequestering, and transport. Concomitant with increased bioenergetic capacity and reduced β-amyloid burden, 2-DG significantly increased expression of neurotrophic growth factors, BDNF and NGF. Results of these analyses demonstrate that dietary 2-DG treatment increased ketogenesis and ketone metabolism, enhanced mitochondrial bioenergetic capacity, reduced β-amyloid generation and increased mechanisms of β-amyloid clearance. Further, these data link bioenergetic capacity with β-amyloid generation and demonstrate that β-amyloid burden was dynamic and reversible, as 2-DG reduced activation of the amyloidogenic pathway and increased mechanisms of β-amyloid clearance. Collectively, these data provide preclinical evidence for dietary 2-DG as a disease-modifying intervention to delay progression of bioenergetic deficits in brain and associated β-amyloid burden.

Oxidative Phosphorylation Is Essential for Felid Sperm Function, but Is Substantially Lower in Cheetah (Acinonyx jubatus) Compared to Domestic Cat (Felis catus) Ejaculate

Compared with the normospermic domestic cat, sperm metabolic function is compromised in the teratospermic cat and cheetah, but the pathway(s) involved in this deficiency are unknown. Glycolysis is essential for sperm motility, yet it appears to function normally in spermatozoa of either species regardless of structural morphology. We conducted a comparative study to further understand the mechanisms of energy production in felid spermatozoa, with the hypothesis that oxidative phosphorylation is required for normal sperm function and is impaired in teratospermic ejaculates. Electroejaculates from both species were stained with MitoTracker to quantify mitochondrial membrane potential (MMP) or were incubated to assess changes in sperm function (motility, acrosomal integrity, and lactate production) after mitochondrial inhibition with myxothiazol. Sperm midpiece dimensions also were quantified. Sperm mitochondrial fluorescence (directly proportional to MMP) was ~95% lower in the cheetah compared with the normospermic and teratospermic cat, despite the cheetah having a 10% longer midpiece. In both species, MMP was increased 5-fold in spermatozoa with retained cytoplasm compared with structurally normal cells. Inhibition of oxidative phosphorylation impaired sperm function in both species, but a 100-fold higher inhibitor concentration was required in the cat compared with the cheetah. Collectively, findings revealed that oxidative phosphorylation was required for sperm function in the domestic cat and cheetah. This pathway of energy production appeared markedly less active in the cheetah, indicating a species-specific vulnerability to mitochondrial dysfunction. The unexpected, cross-species linkage between retained cytoplasmic droplets and elevated MMP may reflect increased concentrations of metabolic enzymes or substrates in these structures.

Energy and environmental potential of solid waste in Brazil

The economic progress and sustainable developments are linked to the optimization and energy conservation. Conventional methods of production and energy utilization usually embed harmful environmental impacts, and hence the challenge to scientists to seek for mechanisms of energy production and use which are less harmful or better still free of unfavorable environmental impacts. Studies point out that municipal solid waste has great energy potential and its reuse, specifically the production of biogas from landfills and the recycling of solid waste presents a favorable mechanism to optimize energy use and preserve it. The present investigation includes the energy savings and the avoided emissions of CO 2 to the atmosphere as a result of recycling and production of biogas from landfills in one metropolitan with more than one million inhabitants and in Brazil. The results show that the rate of CH 4 production from the Brazilian waste landfills can avail for Brazil about 41.7 MW and the reuse of recyclables can avail to the energy system an additional quantity of 286 GJ/month enough for the consumption of 318,000 families.

Turbulence structure and interaction with steep breaking waves

Large-eddy and interface simulation using an interface tracking-based multi-fluid flow solver is conducted to investigate the breaking of steep water waves on a beach of constant bed slope. The present investigation focuses mainly on the ‘weak plunger’ breaking wave type and provides a detailed analysis of the two-way interaction between the mean fluid flow and the sub-modal motions, encompassing wave dynamics and turbulence. The flow is analysed from two points of views: mean to sub-modal exchange, and wave to turbulence interaction within the sub-modal range. Wave growth and propagation are due to energy transfer from the mean flow to the waves, and transport of mean momentum by these waves. The vigorous downwelling–upwelling patterns developing at the head and tail of each breaker are shown to generate both negative- and positive-signed energy exchange contributions in the thin sublayer underneath the water surface. The details of these exchange mechanisms are thoroughly discussed in this paper, together with the interplay between three-dimensional small-scale breaking associated with turbulence and the dominant two-dimensional wave motion. A conditional zonal analysis is proposed for the first time to understand the transient mechanisms of turbulent kinetic energy production, decay, diffusion and transport and their dependence and/or impact on surface wrinkling over the entire breaking process. The simulations provide a thorough picture of air–liquid coherent structures that develop over the breaking process, and link them to the transient mechanisms responsible for their local incidence.

Statistics of particle pair relative velocity in the homogeneous shear flow

Small scale clustering of inertial particles and relative velocity of particle pairs have been fully characterized for statistically steady homogeneous isotropic flows. Depending on the particle Stokes relaxation time, the spatial distribution of the disperse phase results in a multi-scale manifold characterized by local particle concentration and voids and, because of finite inertia, the two nearby particles have high probability to exhibit large relative velocities. Both effects might explain the speed-up of particle collision rate in turbulent flows. Recently it has been shown that the large scale geometry of the flow plays a crucial role in organizing small scale particle clusters. For instance, a mean shear preferentially orients particle patterns. In this case, depending on the Stokes time, anisotropic clustering may occur even in the inertial range of scales where the turbulent fluctuations which drive the particles have already recovered isotropy. Here we consider the statistics of particle pair relative velocity in the homogeneous shear flow, the prototypical flow which manifests anisotropic clustering at small scales. We show that the mean shear, by imprinting anisotropy on the large scale velocity fluctuations, dramatically affects the particle relative velocity distribution even in the range of small scales where the anisotropic mechanisms of turbulent kinetic energy production are sub-dominant with respect to the inertial energy transfer which drives the carrier fluid velocity towards isotropy. We find that the particles’ populations which manifest strong anisotropy in their relative velocities are the same which exhibit small scale clustering. In contrast to any Kolmogorov-like picture of turbulent transport these phenomena may persist even below the smallest dissipative scales where the residual level of anisotropy may eventually blow-up. The observed anisotropy of particle relative velocity and spatial configuration is suggested to influence the directionality of the collision probability, as inferred on the basis of the so-called “ghost collision” model.

Glycolytic flux occurs in Drosophila melanogaster recovering from camptothecin treatment

Camptothecin (CPT) and CPT-derived drugs are widely used against gynaecological and colorectal cancers. On account of their mechanism of action these drugs target rapidly dividing cells and may have an adverse effect on normal tissues. We sought to investigate their impact on normal cells by using Drosophila as a model. We investigated the possible involvement of Drosophila homologue of p53 (Dmp53) and a member of the retinoblastoma binding protein 6 family, known as Snama. On account of its molecular features and experimental evidence gleaned from mammalian studies we propose Snama as a candidate in Dmp53 regulation. We have used proteomics and core molecular biology techniques on embryos and on adult flies. We found that flies that recover from CPT treatment display a metabolic programme characterized by glycolytic flux, depletion of Dmp53 and increase of Snama transcripts. When we introduced methyl pyruvate in the diet to bypass the glycolytic pathway, we noticed differential expression of Dmp53 and Snama and improvement in reproduction and embryonic development. The development of embryos into the pupal stage was significantly improved to 40% (P=0.02) when CPT was given to mothers in combination with methyl pyruvate. This investigation highlights the importance of energy production mechanisms in cells that recover from chemotherapy and differences between the metabolic programmes used by recovering cells and those adopted by cancer cells.

Gene duplications in prokaryotes can be associated with environmental adaptation

BackgroundGene duplication is a normal evolutionary process. If there is no selective advantage in keeping the duplicated gene, it is usually reduced to a pseudogene and disappears from the genome. However, some paralogs are retained. These gene products are likely to be beneficial to the organism, e.g. in adaptation to new environmental conditions. The aim of our analysis is to investigate the properties of paralog-forming genes in prokaryotes, and to analyse the role of these retained paralogs by relating gene properties to life style of the corresponding prokaryotes.ResultsParalogs were identified in a number of prokaryotes, and these paralogs were compared to singletons of persistent orthologs based on functional classification. This showed that the paralogs were associated with for example energy production, cell motility, ion transport, and defence mechanisms. A statistical overrepresentation analysis of gene and protein annotations was based on paralogs of the 200 prokaryotes with the highest fraction of paralog-forming genes. Biclustering of overrepresented gene ontology terms versus species was used to identify clusters of properties associated with clusters of species. The clusters were classified using similarity scores on properties and species to identify interesting clusters, and a subset of clusters were analysed by comparison to literature data. This analysis showed that paralogs often are associated with properties that are important for survival and proliferation of the specific organisms. This includes processes like ion transport, locomotion, chemotaxis and photosynthesis. However, the analysis also showed that the gene ontology terms sometimes were too general, imprecise or even misleading for automatic analysis.ConclusionsProperties described by gene ontology terms identified in the overrepresentation analysis are often consistent with individual prokaryote lifestyles and are likely to give a competitive advantage to the organism. Paralogs and singletons dominate different categories of functional classification, where paralogs in particular seem to be associated with processes involving interaction with the environment.

Shop talk: Annual Drosophila Research Conference, 2010

Shop talk: Annual Drosophila Research Conference, 2010

An assessment of the present and future opportunities for combined heat and power with district heating (CHP-DH) in the United Kingdom

As global fuel reserves are depleted, alternative and more efficient forms of energy generation and delivery will be required. Combined heat and power with district heating (CHP-DH) provides an alternative energy production and delivery mechanism that is less resource intensive, more efficient and provides greater energy security than many popular alternatives. It will be shown that the economic viability of CHP-DH networks depends on several principles, namely (1) the optimisation of engineering and design principles; (2) organisational and regulatory frameworks; (3) financial and economic factors. It was found that in the long term DH is competitive with other energy supply and distribution technologies such as electricity and gas. However, in the short to medium term it is shown that economic risk, regulatory uncertainty and lock-in of existing technology are the most significant barriers to CHP-DH development. This research suggests that under the present regulatory and economic paradigm, the infrastructure required for DH networks remains financially prohibitive; the implementation of government policies are complicated and impose high transaction costs, while engineering solutions are frequently not implemented or economically optimised. If CHP-DH is going to play any part in meeting climate change targets then collaboration between public and private organisations will be required. It is clear from this analysis that strong local government involvement is therefore necessary for the co-ordination, leadership and infrastructural deployment of CHP-DH.

Evaluation of mitochondrial respiratory efficiency during in vitro capacitation of human spermatozoa

The role of mitochondria in sperm motility was the subject of several investigations. However, different views on this topic emerged among scientists. In particular, very little is known on the mechanisms of energy production occurring during human sperm capacitation and related processes. In this study, we have investigated the mitochondrial respiratory efficiency in human sperm samples from normozoospermic subjects before and after swim-up selection and incubation under capacitating condition. Sperm cells, selected by swim-up treatment, were incubated up to 24 h and then demembranated by hypotonic swelling at selected times. The oxygen uptake rate was measured in both basal and swim-up selected samples by a polarographic assay. Mitochondria of swim-up selected cells showed an impressive oxygen consumption rate, which was about 20 times higher than that measured in basal samples. The high mitochondrial respiratory efficiency remained stable up to 24 h after the swim-up treatment. The respiration control ratio, the substrate specificity and the inhibitor sensitivity in the swim-up selected samples were similar to those of basal samples thereby suggesting that the physiology of mitochondria was preserved after the swim-up treatment. Furthermore, the remarkably high mitochondrial respiration in swim-up selected samples allowed the oxygraphic analysis of just 200,000 sperm cells. Sperm selection and incubation under capacitating condition are therefore associated with a high activity of the mitochondrial respiratory chain. The sperm oxygen consumption rate could be useful to exclude mitochondria malfunctioning in male infertility.

Overexpression of TUF1 restores respiratory growth and fluconazole sensitivity to a Cryptococcus neoformans vad1Δ mutant

The yeast-like fungus Cryptococcus neoformans favours respiration as a mechanism of energy production, and thus depends heavily on mitochondrial function. Previous studies of a C. neoformans vad1Δ mutant revealed reduced expression of the mitochondrial elongation factor TUF1 and defects in glycerol utilization, consistent with mitochondrial dysfunction. In this study, we found that in trans expression of TUF1 in the vad1Δ mutant suppressed the mitochondrial defects, including growth on respiration-dependent carbon sources and fluconazole resistance, associated with VAD1 deletion. Tetracycline, an inhibitor of mitochondrial translation, was found to confer resistance to fluconazole in the wild-type and vad1Δ mutant, whereas the fluconazole susceptibility of the TUF1-overexpressing strain was unaffected by tetracycline treatment. In the presence of fluconazole, the vad1Δ mutant exhibited increased activation of the global transcriptional regulator Sre1. TUF1 overexpression failed to alter cleavage of Sre1 in response to fluconazole in the vad1Δ mutant, suggesting that TUF1 repression in the vad1Δ mutant is distal to Sre1, or that it occurs through an independent pathway.

Necrotic retinal pigment epithelium in toxoplasmic retinochoroiditis

Editor, We read with interest Belfort and colleagues’ clinicopathological report on a case of toxoplasmic retinochoroiditis, published in Acta Ophthalmologica (Belfort et al. 2008). The authors describe the histopathological findings of an enucleated globe of a 66-year-old immunosuppressed man with severe bilateral posterior uveitis that had progressed despite antiviral therapy for presumed cytomegalovirus retinitis. This article illustrated well the role of histopathological examination and immunohistochemistry in establishing definitively the aetiology in these challenging cases. However some of the authors’ histopathological observations deserve further comments. The authors stated that, in addition to the necrotizing retinitis and the granulomatous inflammation of the choroid, ‘necrosis of Bruch’s membrane’ might be a distinctive feature of toxoplasmic retinochoroiditis. However, histopathologically such a term is a misnomer. Necrosis is the morphological expression of cell death and is characterized by protein denaturation, loss of energy producing mechanisms, enzymatic cellular digestion and often a secondary inflammatory response (Spencer 1996). Being essentially an acellular structure, made up of the basement membranes of the retinal pigment epithelium (RPE) and of the choriocapillaris in each side, and of a core elastic layer surrounded by two collagenous zones (Garron 1963), Bruch’s membrane may undergo secondary pathological changes but not necrosis, and this term should be avoided. The secondary changes in Bruch’s membrane reflect the involvement of RPE and/or of choriocapillaris endothelium. RPE necrosis is shown nicely in their Fig. 1E (Belfort et al. 2008), and has been recognized not only in cases of toxoplasmic retinochoroiditis (Rao & Font 1977) but also in other necrotizing retinites secondary to mycobacteria, fungi, viruses and even in primary retinal lymphoma (Spencer 1996; Rao et al. 2006). Finally, according to the authors, the involvement and eventual disruption of Bruch’s membrane might justify the occurrence of secondary granulomatous inflammation of the choroid in toxoplasmic retinochoroiditis. Nevertheless this is unlikely, because in many of the entities listed earlier, secondary inflammation of the choroid occurs despite an uninterrupted Bruch’s membrane (Spencer 1996). We congratulate Belfort and colleagues on their interesting article, emphasizing the role of histopathology on the aetiological diagnosis of these complex cases.

Age-related changes of monoaminooxidases in rat cerebellar cortex.

Age-related changes of the monoaminoxidases, evaluated by enzymatic staining, quantitative analysis of images, biochemical assay and statistical analysis of data were studied in cerebellar cortex of young (3-month-old) and aged (26-month-old) male Sprague-Dawley rats. The enzymatic staining shows the presence of monoamino-oxidases within the molecular and granular layers as well as within the Purkinje neurons of the cerebellum of young and aged animals. In molecular layer, and in Purkinje neurons the levels of monoaminooxidases were strongly increased in old rats. The granular layer showed, on the contrary, an age-dependent loss of enzymatic staining. These morphological findings were confirmed by biochemical results. The possibility that age-related changes in monoaminooxidase levels may be due to impaired energy production mechanisms and/or represent the consequence of reduced energetic needs is discussed.

Particle modulations to turbulence in two-phase round jets

The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant attenuations of turbulence intensities were measured in the far-fields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle properties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.