Energy Transduction Research Articles

Nanoparticles in plant resistance against bacterial pathogens: current status and future prospects.

Nanoparticles (NPs) serve immense roles in various fields of science. They have vastly upgraded conventional methods in the fields of agriculture and food sciences to eliminate growing threats of crop damage and disease, caused by various phytopathogens including bacteria, fungi, viruses, and some insects. Bacterial diseases resulted in mass damage of crops by adopting antibacterial resistance, which has proved to be a major threat leading to food scarcity. Therefore, numerous NPs with antibacterial potentials have been formulated to overcome the problem of antibiotic resistance alongside an increase in crop yield and boosting plant immunity. NPs synthesized through green synthesis techniques have proved to be more effective and environment-friendly than those synthesized via chemical methods. NPs exhibit great roles in plants ranging from enhanced crop yield to disease suppression, to targeted drug and pesticide deliveries inside the plants and acting as biosensors for pathogen detection. NPs serves major roles in disruption of cellular membranes, ROS production, altering of DNA and protein entities and changing energy transductions. This review focuses on the antibacterial effect of NPs on several plant bacterial pathogens, mostly, against Pseudomonas syringe, Ralstonia solanacearum, Xanthomonas axonopodis, Clavibacter michiganensisand Pantoea ananatis both in vivo and ex vivo, thereby minimizing their antibacterial resistance and enhancing the plants acquired immunity. Therefore, NPs present a safer and more reliable bactericidal activity against various disease-causing bacteria in plants.

Photo- and electrochemical properties of newly synthesized thioxathone-viologen-fluorene ternary compound and its electrochromic device

External stimuli-responsive materials exhibit widespread potential applications in sensors, smart windows, displays, and opto-electronic molecular devices. In this study, we report light-/electrochemically induced chromic behaviors of newly synthesized ternary compound in the device. This compound is composed of a light-harvesting unit of thioxathone (TX), an electron donor of fluorene (FL), and an electron mediator of viologen (VIO), and thus it can act as a photochromic species with an intramolecular electron transfer under irradiation. The precursors of TX and FL substituents give off broad emissions at approximately 437 and 310 − 330 nm, respectively. Both emissions are largely quenched in the TX-VIO-FL ternary compound, which is caused by an intramolecular transduction of energy from the excited singlet FL and TX to the electroactive VIO substituent. Based on cyclic voltammogram of TX-VIO-FL modified electrodes, two reversible waves are observed at around − 0.44 and − 0.89 V (vs Hg/Hg2Cl2), attributed to the electron transport processes of TX-VIO2+-FL ↔ TX-VIO+•-FL and TX-VIO+•-FL ↔ TX-VIO0-FL, respectively. Sandwiched type of photo-/electrochromic devices are constructed, displaying a good transmittance and reversible viologen color change behavior under irradiation or an applied bias of − 2.6 V.

H+-slip correlated to rotor free-wheeling as cause of F1FO-ATPase dysfunction in primary mitochondrial disorders.

Inborn errors of metabolism are related to mitochondrial disorders caused by dysfunction of the oxidative phosphorylation (OXPHOS) system. Congenital hypermetabolism in the infant is a rare disease belonging to Luft syndrome, nonthyroidal hypermetabolism, arising from a singular example of a defect in OXPHOS. The mitochondria lose coupling of mitochondrial substrates oxidation from the ADP phosphorylation. Since Luft syndrome is due to uncoupled cell respiration responsible for deficient in ATP production that originates in the respiratory complexes, a de novo heterozygous variant in the catalytic subunit of mitochondrial F1FO-ATPase arises as the main cause of an autosomal dominant syndrome of hypermetabolism associated with dysfunction in ATP production, which does not involve the respiratory complexes. The F1FO-ATPase works as an embedded molecular machine with a rotary action using two different motor engines. The FO, which is an integral domain in the membrane, dissipates the chemical potential difference for H+, a proton motive force (Δp), across the inner membrane to generate a torsion. The F1 domain-the hydrophilic portion responsible for ATP turnover-is powered by the molecular rotary action to synthesize ATP. The structural and functional coupling of F1 and FO domains support the energy transduction for ATP synthesis. The dissipation of Δp by means of an H+ slip correlated to rotor free-wheeling of the F1FO-ATPase has been discovered to cause enzyme dysfunction in primary mitochondrial disorders. In this insight, we try to offer commentary and analysis of the molecular mechanism in these impaired mitochondria.

3D nanofabricated soft microrobots with super-compliant picoforce springs as onboard sensors and actuators.

Microscale organisms and specialized motile cells use protein-based spring-like responsive structures to sense, grasp and move. Rendering this biomechanical transduction functionality in an artificial micromachine for applications in single-cell manipulations is challenging due to the need for a bio-applicable nanoscale spring system with a large and programmable strain response to piconewton-scale forces. Here we present three-dimensional nanofabrication and monolithic integration, based on an acrylic elastomer photoresist, of a magnetic spring system with quantifiable compliance sensitive to 0.5 pN, constructed with customized elasticity and magnetization distributions at the nanoscale. We demonstrate the effective design programmability of these 'picospring' ensembles as energy transduction mechanisms for the integrated construction of customized soft micromachines, with onboard sensing and actuation functions at the single-cell scale for microrobotic grasping and locomotion. The integration of active soft springs into three-dimensional nanofabrication offers an avenue to create biocompatible soft microrobots for non-disruptive interactions with biological entities.

General efficiency relation for dissipative molecular machines

Living systems use chemical fuel to process information, assemble structures and maintain fluxes. Many of these processes are dissipative: energy is consumed purely to maintain non-equilibrium steady-state outputs. How efficiently the input energy is transduced toward the output dissipation as opposed to being lost during intermediate steps, and whether the efficiency is constrained by general principles or specific fine-tuning, are open questions. Here, applying a recent mapping from non-equilibrium systems to battery-resistor circuits, an analytic expression for the efficiency of any dissipative molecular machine driven by a chemical potential difference is derived. This expression disentangles the chemical potential from the machine’s details, whose effect on the efficiency is fully specified by a constant called the load resistance. The efficiency passes through an inflection point separating totally inefficient machines from efficient machines if the balance between chemical potential difference and load resistance exceeds thermal noise. This explains all-or-none dynein stepping with increasing ATP concentration observed in single-molecule experiments. These results indicate that energy transduction in living systems is efficient not because of idiosyncratic optimization of biomolecules, but rather because the concentration of chemical fuel is kept above a threshold level.

Energy harvesting and inter-floor impact noise control using an optimally tuned hybrid damping system

Impact-loaded floor structures radiate undesired sound waves into adjacent rooms, compromising the acoustic comfort. On the other hand, substantial structural vibrations caused by the impact loading offer a promising energy source for harvesting. Nevertheless, a systematic analytical or numerical investigation of simultaneous inter-floor impact sound transmission control and energy harvesting appears to be missing. Current study describes the conceptual development of a fully coupled 3D analytical model of a dual-functional double-plate floor structure optimized for hybrid regenerative control of inter-floor impact sound transmission. Leveraging multi-mode shunted piezoelectric and Electromagnetic Damper (EMD) energy transduction mechanisms, the model structure is composed of two PZT sandwich plates, which are interlinked through a Nonlinear Vibration Absorber (NVA)-based EMD. The finite Fourier cosine transform and standard normal mode approach are employed to treat the governing acousto-elastic equations. Non-dominated Sorting Genetic Algorithm II is applied to tune the system parameters along Pareto frontiers to target maximum pressure mitigation, maximum energy harvesting, or dual-objective optimization, which hires advantageous features from both configurations for an optimal trade-off between them. Simulations reveal that elasto-acoustic response suppression and energy extraction of the employed stand-alone PZT-based conversion mechanism can be remarkably improved with the adopted optimized hybrid PZT/NVA/EMD-equipped system.

Methods to monitor mitochondrial disulfide bonds.

Mitochondria contain numerous proteins that utilize the chemistry of cysteine residues, which can be reversibly oxidized. These proteins are involved in mitochondrial biogenesis, protection against oxidative stress, metabolism, energy transduction to adenosine triphosphate, signaling and cell death among other functions. Many proteins located in the mitochondrial intermembrane space are imported by the mitochondrial import and assembly pathway the activity of which is based on the reversible oxidation of cysteine residues and oxidative trapping of substrates. Oxidative modifications of cysteine residues are particularly difficult to study because of their labile character. Here we present techniques that allow for monitoring the oxidative state of mitochondrial proteins as well as to investigate the mitochondrial import and assembly pathway. This chapter conveys basic concepts on sample preparation and techniques to monitor the redox state of cysteine residues in mitochondrial proteins as well as the strategies to study mitochondrial import and assembly pathway.

Dynamic organic crystals as exceptionally efficient artificial natural light-harvesting actuators.

Dynamic organic crystal materials that can directly convert solar energy into mechanical work hold the potential to be efficient artificial actuators. However, developing dynamic organic crystals that can efficiently transform natural light energy into mechanical energy is still quite challenging. Herein, a novel dynamic organic crystal whose two polymorphs (Form I and Form II) are both capable of effectively converting natural light into work was successfully synthesized. Under the irradiation of ultraviolet (UV), blue and natural light, the on/off toggling of a photosalient effect could be triggered. Specifically, under UV light irradiation, Form I demonstrates output work densities of about 4.2-8.4 × 104 J m-3 and 1.6-4.9 × 102 J m-3 before and after disintegration, respectively. Form II exhibits output work densities of about 1.3 × 102 to 1.9 × 103 J m-3 by means of photoinduced bending, suggesting that controllable bending may be more favorable for energy harvesting than the photosalient effect. Utilizing the exceptionally high energy transduction efficiency of Form I, we developed a natural light-driven micro-actuator that can realize output work densities of 2.8-5.0 × 104 J m-3. The natural light-harvesting performance of this actuator significantly surpasses those of previously reported photomechanical crystals and could even be comparable to thermal actuators.

Lipid lateral diffusion: mechanisms and modulators.

The lateral diffusion of lipids within a membrane is of paramount importance, serving as a central mechanism in numerous physiological processes including cell signaling, membrane trafficking, protein activity regulation, and energy transduction pathways. This review offers a comprehensive overview of lateral lipid diffusion in model biomembrane systems explored through the lens of neutron scattering techniques. We examine diverse models of lateral diffusion and explore the various factors influencing this fundamental process in membrane dynamics. Additionally, we offer a thorough summary of how different membrane-active compounds, including drugs, antioxidants, stimulants, and membrane proteins, affect lipid lateral diffusion. Our analysis unveils the intricate interplay between these additives and membranes, shedding light on their dynamic interactions. We elucidate that this interaction is governed by a complex combination of multiple factors including the physical state and charge of the membrane, the concentration of additives, the molecular architecture of the compounds, and their spatial distribution within the membrane. In conclusion, we briefly discuss the future directions and areas requiring further investigation in the realm of lateral lipid diffusion, highlighting the need to study more realistic membrane systems.

Proton-coupled electron transfer dynamics in the alternative oxidase.

The alternative oxidase (AOX) is a membrane-bound di-iron enzyme that catalyzes O2-driven quinol oxidation in the respiratory chains of plants, fungi, and several pathogenic protists of biomedical and industrial interest. Yet, despite significant biochemical and structural efforts over the last decades, the catalytic principles of AOX remain poorly understood. We develop here multi-scale quantum and classical molecular simulations in combination with biochemical experiments to address the proton-coupled electron transfer (PCET) reactions responsible for catalysis in AOX from Trypanosoma brucei, the causative agent of sleeping sickness. We show that AOX activates and splits dioxygen via a water-mediated PCET reaction, resulting in a high-valent ferryl/ferric species and tyrosyl radical (Tyr220˙) that drives the oxidation of the quinol via electric field effects. We identify conserved carboxylates (Glu215, Asp100) within a buried cluster of ion-pairs that act as a transient proton-loading site in the quinol oxidation process, and validate their function experimentally with point mutations that result in drastic activity reduction and pK a-shifts. Our findings provide a key mechanistic understanding of the catalytic machinery of AOX, as well as a molecular basis for rational drug design against energy transduction chains of parasites. On a general level, our findings illustrate how redox-triggered conformational changes in ion-paired networks control the catalysis via electric field effects.

Development and characterization of acoustic energy harvesters for low power wireless sensor network

Wireless Sensor Nodes (WSNs) have developed significantly over the years and have a significant potential in diverse applications in the fields of science and technology. The inadequate energy accompanying with WSNs is a key constraint of WSN skills. To overwhelm this main restraint, the development and expansion of effective and reliable energy harvesting systems for WSN atmospheres are being discovered. In this research, low power acoustic affordable and clean energy harvesters are designed and developed by applying different techniques of energy transduction from the sound available in the surroundings. Three acoustic energy harvesters were developed based on piezoelectric phenomenon, electromagnetic transduction & Hybrid respectively. The CAD modelling, lumped modelling and Finite Element Analysis of the harvesters were carried out. The voltages were obtained using FEA for each Acoustic Harvester. Characterization of all the three harvesters were carried out and the power generated by piezoelectric harvester, electromagnetic harvester and Hybrid Acoustic Energy harvester are 2.25x10-9W, 0.0533W and 0.0232W respectively.

SENTRI: Single-Particle Energy Transducer for Radionuclide Injections for Personalized Targeted Radionuclide Cancer Therapy

IntroductionTargeted radionuclide therapy (TRT), whereby a tumor-targeted molecule is linked to a therapeutic beta- or alpha-emitting radioactive nuclide, is a promising treatment modality for patients with metastatic cancer, delivering radiation systemically. However, patients still progress due to suboptimal dosing, driven by the large patient to patient variability. Therefore, the ability to continuously monitor the real-time dose deposition in tumors and organs at risk (OARs) provides an additional dimension of information during clinical trials that can enable insights into better strategies to personalize TRT. MethodsHere, we present a single beta-particle sensitive dosimeter consisting of a 0.27 mm3 monolithic silicon chiplet, directly implanted into the tumor. To maximize the sensitivity and have enough detection area, minimum size diodes (1 μm2) are arrayed in 64 × 64. Signal amplifiers, buffers, and on chip memories are all integrated in the chip. For verification, PC3-PIP (PSMA+) and PC3-flu (PSMA-) cell lines are injected into the left and right flanks of the mice, respectively. The devices are inserted into each tumor, measure activities at 5 different time points (0-2 hour, 7-9 hour, 12-14 hour, 24-26 hour, and 48-50 hour) post 177Lu-PSMA-617 injections. SPECT/CT scans are used to verify measured data. ResultWith a wide detection range from 0.013 to 8.95 MBq/mL, the system is capable of detecting high tumor uptake, as well as low doses delivered to OARs in real time. The measurement data is highly proportional (R2 > 0.99) to the 177Lu-PSMA-617 activity. The in vivo measurement data agrees well with the SPECT/CT results within acceptable errors (±1.5 %ID/mL). ConclusionGiven the recent advances in clinical use of TRT in prostate cancer, the proposed system is verified in a prostate cancer mouse model using 177Lu-PSMA-617.

Evidence of an intracellular creatine-sensing mechanism that modulates creatine biosynthesis via AGAT expression in human HAP1 cells

Cellular homeostasis of creatine (CT), integral part of the energy buffering and transducing system connecting intracellular sites of ATP production and utilization, comprises of mechanisms that increase CT, i.e., biosynthesis and cellular uptake, and CT-lowering processes, such as export and non-enzymatic conversion to creatinine. The biosynthesis of CT is controlled by negative feedback loop via suppression of the rate-limiting enzyme arginine:glycine amidinotransferase (AGAT). Although the regulatory mechanism involved is not well understood, AGAT suppression is successfully used in patients with guanidinoacetate methyltransferase (GAMT) deficiency to reduce the neurotoxic accumulation of the AGAT-mediated guanidinoacetate production by supplementing patients with CT. Utilizing the CT-dependent feedback loop for the upregulation of AGAT expression may well represent a therapeutic target for an additional CT deficiency syndrome, the CT transporter (CrT) defect, for which no effective treatment option is available so far. We have used CRISPR to tag the C-terminus of AGAT with a nanoluc luciferase (NLuc) reporter in HAP1 cells. A biphasic decay of AGAT-NLuc in response to increasing extracellular CT was observed, whereas the decrease in AGAT-NLuc expression was directly proportional to the rise in intracellular CT levels with an approximate IC50 of 1–2 mM. CRISPR generated HAP1 CrT null cells and HAP1 CrT null cells stably expressing a CrT-GFP fusion protein further demonstrated that the biphasic response to extracellular CT is mediated by a high-affinity (Km 9–10 µM) CrT dependent, saturable mechanism and a CrT independent, unsaturable uptake process. The direct response to intracellular CT suggests the existence of an intracellular CT sensing system enabling a dynamic cell response to changing CT concentration that is relevant for cellular CT homeostasis.

Numerical Methods to Evaluate Hyperelastic Transducers: Hexagonal Distributed Embedded Energy Converters

Hexagonal distributed embedded energy converters, also known as hexDEECs, are centimeter-scale energy transducers that leverage variable capacitance to generate electricity when their hyperelastic structure is dynamically deformed. To better understand, characterize, and optimize hexDEEC designs, a series of numerical methods and techniques were developed to model the hyperelastic mechanics of hexDEECs, electrostatic properties, and electricity generation characteristics. The numerical methods developed for the hyperelastic structural analysis were corroborated by empirical results from another study, and the models and equations for capacitance, electrostatic forces, and electrical potential energy were derived from fundamental electrostatic equations. These methods and techniques were implemented within the STAR-CCM+ multiphysics software Version 2020.3 (15.06.008) environment. Results from this analysis revealed methodologies and techniques necessary to model the energy converters, which will enable future exploration and optimization of more specific designs and corresponding applications.

Pyruvate modulation of redox potential controls mouse sperm motility

Sperm gain fertilization competence in the female reproductive tract through a series of biochemical changes and a requisite switch from linear progressive to hyperactive motility. Despite being essential for fertilization, regulation of sperm energy transduction is poorly understood. This knowledge gap confounds interpretation of interspecies variation and limits progress in optimizing sperm selection for assisted reproduction. Here, we developed a model of mouse sperm bioenergetics using metabolic phenotyping data, quantitative microscopy, and spectral flow cytometry. The results define a mechanism of motility regulation by microenvironmental pyruvate. Rather than being consumed as a mitochondrial fuel source, pyruvate stimulates hyperactivation by repressing lactate oxidation and activating glycolysis in the flagellum through provision of nicotinamide adenine dinucleotide (NAD)+. These findings provide evidence that the transitions in motility requisite for sperm competence are governed by changes in the metabolic microenvironment, highlighting the unexplored potential of using catabolite combination to optimize sperm selection for fertilization.

Role of transcriptomic and genomic analyses in improving the comprehension of cefiderocol activity in Acinetobacter baumannii.

The mechanisms of action and resistance of cefiderocol (FDC) in Acinetobacter baumannii are still not fully elucidated, but iron transport systems have been evoked in its entry into the cell to reach the penicillin-binding proteins (PBPs). To capture the dynamics of gene expression related to FDC action in various conditions, we report on the genomic and transcriptomic features of seven A. baumannii strains with different FDC susceptibility, focusing on the variants in genes associated with β-lactam resistance and the expression of the siderophore biosynthesis and transport systems acinetobactin and baumannoferrin. We also investigated the expression of the TonB energy transduction system (ETS) and siderophore receptors piuA and pirA. The four clinical samples belonged to the same clonal complex (CC2), and the two strains with the highest FDC MICs showed peculiar variants in PBP2 and ampC. Similarly, the two clinical strains with the lowest MICs shared variants in an outer membrane protein as well as ampC. Gene expression analyses highlighted the up-regulation of the acinetobactin and baumannoferrin genes in response to iron depletion and a down-regulation in the presence of high iron concentrations. In response to FDC, gene expression seemed strain-dependent, probably due to the different metabolic features of each strain. Overall, FDC activates the ETS, confirming the active import of the drug; baumannoferrin, more than acinetobactin, appeared stimulated by FDC in an iron-depleted medium. In conclusion, iron transport systems play a clear role in the FDC uptake, and their expression likely contributes to MIC variation together with β-lactam resistance determinants.IMPORTANCEAcinetobacter baumannii poses a threat to healthcare due to its ability to give difficult-to-treat infections as a consequence of our shortage of antibiotic molecules active on this multidrug-resistant bacterium. Cefiderocol (FDC) represents one of the few drugs active on A. baumannii, and to preserve its activity, this study explored the transcriptomic and genomic features of seven strains with varying susceptibility to FDC. Transcriptomic analyses revealed the different effects of FDC on iron transport systems, promoting mainly baumannoferrin expression-thus more likely related to FDC entry-and the energy transduction systems. These findings suggest that not all iron transport systems are equally involved in FDC entry into A. baumannii cells. Finally, mutations in PBPs and β-lactamases may contribute to the resistance onset. Overall, the study sheds light on the importance of iron availability and metabolic differences in FDC resistance, offering insights into understanding the evolution of resistance in A. baumannii strains.

Spatio-temporal distribution characteristics and influencing factors of protoporphyrin IX in the estuarine-coastal ecosystems

Protoporphyrin IX (PPIX), a key precursor for the synthesis of chlorophyll and heme, is fundamental to photosynthetic eukaryotic cells and participates in light absorption, energy transduction, and numerous other cellular metabolic activities. Along with the application of genetic and biochemical techniques over the past few years, our understanding of the formation of PPIX has been largely advanced, especially regarding possible metabolic pathways. However, the ecological role and function of PPIX in natural ecosystems remains unclear. We have previously established a method for quantifying PPIX in marine ecosystems. Here, our results provide evidence that PPIX is not only subtly linked to nutrient uptake but also triggers phytoplankton productivity. PPIX and its derivatives are dynamic spatiotemporally in direct response to increased nutrient availability. Using 16 S rRNA gene amplicon sequencing, PPIX was revealed to interact strongly with many microorganisms, indicating that PPIX serves as a critical metabolite in maintaining microbial metabolism and community development. In summary, we observed that PPIX is linearly related to nutrient availability and microbial diversity. The levels of microbial PPIX reflect ecological health, and the availability of PPIX and nutrients jointly affect microbial community composition.

Transduction of UV-light energy into alternating-current electricity via a neglected internal photoelectric effect of metal foil-based nanogenerator

Massive free electrons in metals could escape from the metal surface to generate a convection current when colliding with high-energy photons (e.g. UV light). Namely, metals with specific work functions could transduce light energy into direct-current (DC) electricity via the famous external photoelectric effect. However, obtaining alternating-current (AC) electricity via a non-Faraday’s law of electromagnetic induction directly using metal foil is challenging. Inspired by our recent work, we herein for the first time report a subtle method to directly transduce UV light energy into AC electricity by metal foil nanogenerators and propose a new mechanism regarding the transduction of UV light into AC electricity entitled the neglected internal photoelectric effect (NIPE). According to the NIPE, a zinc foil-based NIPE nanogenerator (NIPEG) can output an optimal open-circuit voltage (Voc) and a short-circuit current (Isc) of 108 V and 320 μA, respectively. The maximum output power and the photoelectric conversion efficiency of the fabricated nanogenerator approach 23.9 W m−2 and 77.02%, respectively. Meantime, the electrical energy stored in the capacitor connected to the Zn foil-based nanogenerator after rectification is several orders of magnitude higher than that of the conventional Cu/PTFE/PET/Cu-based triboelectric nanogenerator and Cu/PTFE/Al-based water droplet nanogenerator. The herein approach potentially offers a novel energy harvesting and conversion avenue to develop self-powered and wearable electronic devices.

Selenite ameliorates the ATP hydrolysis of mitochondrial F1FO-ATPase by changing the redox state of thiol groups and impairs the ADP phosphorylation

Selenite as an inorganic form of selenium can affect the redox state of mitochondria by modifying the thiol groups of cysteines. The F1FO-ATPase has been identified as a mitochondrial target of this compound. Indeed, the bifunctional mechanism of ATP turnover of F1FO-ATPase was differently modified by selenite. The activity of ATP hydrolysis was stimulated, whereas the ADP phosphorylation was inhibited. We ascertain that a possible new protein adduct identified as seleno-dithiol (-S-Se-S-) mercaptoethanol-sensitive caused the activation of F-ATPase activity and the oxidation of free –SH groups in mitochondria. Conversely, the inhibition of ATP synthesis by selenite might be irreversible. The kinetic analysis of the activation mechanism was an uncompetitive mixed type with respect to the ATP substrate. Selenite bound more selectively to the F1FO-ATPase loaded with the substrate by preferentially forming a tertiary (enzyme-ATP-selenite) complex. Otherwise, the selenite was a competitive mixed-type activator with respect to the Mg2+ cofactor. Thus, selenite more specifically bound to the free enzyme forming the complex enzyme-selenite. However, even if the selenite impaired the catalysis of F1FO-ATPase, the mitochondrial permeability transition pore phenomenon was unaffected. Therefore, the reversible energy transduction mechanism of F1FO-ATPase can be oppositely regulated by selenite.

The allometry of mitochondrial efficiency is tissue dependent: a comparison between skeletal and cardiac muscles of birds.

Body mass is known to be a fundamental driver of many biological traits, including metabolism. However, the effect of body mass on mitochondrial energy transduction is still poorly understood and has mainly been described in mammals. Using 13 species of birds ranging from 15 g (finches) to 160 kg (ostrich), we report here that the mitochondrial production of ATP, and the corresponding oxygen consumption, are negatively dependent on body mass in skeletal muscles but not in the heart. Results also showed that mitochondrial efficiency was positively correlated with body mass at sub-maximal phosphorylating states in the skeletal muscle, but not in the heart. This difference between muscle tissues is potentially linked to the difference in energetic demand expandability and the heavy involvement of skeletal muscle in thermoregulation.