Enhancing biofilm resistance and ATP synthesis accelerates toluene degradation at low temperature via AHLs-mediated quorum sensing.

BackgroundInsulin resistance is the best predictor for the development of type 2 diabetes. Recent studies have shown that young, lean, insulin-resistant (IR) offspring of parents with type 2 diabetes have reduced basal rates of muscle mitochondrial phosphorylation activity associated with increased intramyocellular lipid (IMCL) content, which in turn blocks insulin signaling and insulin action in muscle. In order to further characterize mitochondrial activity in these individuals, we examined insulin-stimulated rates of adenosine triphosphate (ATP) synthesis and phosphate transport in skeletal muscle in a similar cohort of participants.Methods and FindingsRates of insulin-stimulated muscle mitochondrial ATP synthase flux and insulin-stimulated increases in concentrations of intramyocellular inorganic phosphate (Pi) were assessed by 31P magnetic resonance spectroscopy (MRS) in healthy, lean, IR offspring of parents with type 2 diabetes and healthy, lean control participants with normal insulin sensitivity. IMCL content in the soleus muscle of all participants was assessed by 1H MRS. During a hyperinsulinemic-euglycemic clamp, rates of insulin-stimulated glucose uptake were decreased by approximately 50% in the IR offspring compared to the control participants (p = 0.007 versus controls) and were associated with an approximately 2-fold increase in IMCL content (p < 0.006 versus controls). In the control participants rates of ATP synthesis increased by approximately 90% during the hyperinsulinemic-euglycemic clamp. In contrast, insulin-stimulated rates of muscle mitochondrial ATP synthesis increased by only 5% in the IR offspring (p = 0.001 versus controls) and was associated with a severe reduction of insulin-stimulated increases in the intramyocellular Pi concentrations (IR offspring: 4.7% ± 1.9% versus controls: 19.3% ± 5.7%; p = 0.03). Insulin-induced increases in intramyocellular Pi concentrations correlated well with insulin-stimulated increases in rates of ATP synthesis (r = 0.67; p = 0.008).ConclusionsThese data demonstrate that insulin-stimulated rates of mitochondrial ATP synthesis are reduced in IR offspring of parents with type 2 diabetes. Furthermore, these IR offspring also have impaired insulin-stimulated phosphate transport in muscle, which may contribute to their defects in insulin-stimulated rates of mitochondrial ATP synthesis.

Cellular interactions of kinesin-1, an adenosine triphosphate (ATP)-driven motor protein capable of undergoing multiple steps on a microtubule (MT), affect its mechanical processivity, the number of steps taken per encounter with MT. Even though the processivity of kinesin has been widely studied, a detailed study of the factors that affect the stepping of the motor along MT is still lacking. We model the cellular interactions of kinesin as a probabilistic timed automaton and use the model to simulate the mechanical processivity of the motor. Theoretical analysis suggests: (i) backward stepping tends to be powered by ATP hydrolysis, rather than ATP synthesis, (ii) backward stepping powered by ATP synthesis is more likely to happen with limiting ATP concentration ([ATP]) at high loads and (iii) with increasing load the frequency of backward stepping powered by ATP hydrolysis at high [ATP] is greater than that powered by ATP synthesis at limiting [ATP]. Together, the higher frequency of backward stepping powered by ATP hydrolysis than by ATP synthesis is found to be a reason for the more dramatic falling of kinesin processivity with rising load at high [ATP] compared with that at low [ATP]. Simulation results further show that the processivity of kinesin can be determined by the number of ATP hydrolysis and synthesis kinetic cycles taken by the motor before becoming inactive. It is also found that the duration of a backward stepping cycle at high loads is more likely to be less than that of a forward stepping cycle. h.r.khataee@griffithuni.edu.au or a.liew@griffith.edu.au.

Following the recent demonstration of increased mitochondrial DNA mutations in lymphocytes of POAG patients, the authors sought to characterize mitochondrial function in a separate cohort of POAG. Using similar methodology to that previous applied to Leber's hereditary optic neuropathy (LHON) patients, maximal adenosine triphosphate (ATP) synthesis and cellular respiration rates, as well as cell growth rates in glucose and galactose media, were assessed in transformed lymphocytes from POAG patients (n = 15) and a group of age- and sex-matched controls (n = 15). POAG lymphoblasts had significantly lower rates of complex-I-driven ATP synthesis, with preserved complex-II-driven ATP synthesis. Complex-I driven maximal respiration was also significantly decreased in patient cells. Growth in galactose media, where cells are forced to rely on mitochondrial ATP production, revealed no significant differences between the control and POAG cohort. POAG lymphoblasts in the study cohort exhibited a defect in complex-I of the oxidative phosphorylation pathway, leading to decreased rates of respiration and ATP production. Studies in LHON and other diseases have established that lymphocyte oxidative phosphorylation measurement is a reliable indicator of systemic dysfunction of this pathway. While these defects did not impact lymphoblast growth when the cells were forced to rely on oxidative ATP supply, the authors suggest that in the presence of a multitude of cellular stressors as seen in the early stages of POAG, these defects may lead to a bioenergetic crisis in retinal ganglion cells and an increased susceptibility to cell death.

PURPOSE: To investigate the influence of group III/IV muscle afferent feedback on skeletal muscle force production and bioenergetics during all-out exercise. METHODS: Phosphorous magnetic resonance spectroscopy was performed during a 5-min all-out intermittent isometric single-leg knee-extensor exercise, consisting of 60 maximal voluntary contractions (MVC), with intrathecal fentanyl (FENT), to attenuate group III/IV leg muscle afferents, and control (CTRL) conditions in 8 healthy men (age: 28 ± 5 yrs, stature: 178 ± 4 cm, and body mass: 77 ± 8 kg). Peak, integrated, and mean forces were determined per MVC and critical force (CF) was determined as the mean force of the final 6 MVCs. The intramuscular metabolic perturbation and adenosine triphosphate (ATP) synthesis rates were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4−), ATP, and pH. RESULTS: Peak force (FENT: 595 ± 113 vs. CTRL: 568 ± 126 N) and end-test force (FENT: 224 ± 50 vs. CTRL: 209 ± 52) were not significantly different between conditions. The cumulative integrated force was significantly greater for FENT than CTRL over the 1st min (17557 ± 2581 vs. 16154 ± 2825 N), but not thereafter (Figure 1). End-exercise [PCr] was not significantly different between conditions, while [Pi] and [H2PO4−] were significantly greater for FENT. The estimated total ATP synthesis rate was significantly greater for FENT than CTRL over the 1st min (66 ± 16 vs. 57 ± 13 mM), but not thereafter (Figure 1). The estimated total ATP synthesis rate at CF arose from a significantly greater oxidative ATP synthesis (FENT: 77 ± 15 vs. CTRL: 83 ± 13 %) than anaerobic ATP synthesis (FENT: 23 ± 15 vs. CTRL 17 ± 13 %). CONCLUSION: Attenuation of group III/IV muscle afferent feedback augmented force production during the 1st min of all-out exercise, for which the increased energy demand was met, en masse, by the creatine kinase reaction, glycolysis, and oxidative metabolism.

8 - Physiology of Mitochondria

To investigate the effects of pyrrolidine dithiocarbamate (PDTC) on oxidative stress and mitochondrial function of lung tissue in mice with acute lung injury (ALI) induced by lipopolysaccharide (LPS). Forty female Balb/c mice were randomly divided into normal saline (NS) control group, LPS model group, PDTC group, and PDTC+LPS group, with 10 mice in each group. The model of mice with ALI was reproduced by intraperitoneal injection of 15 mg/kg LPS. PDTC was administered intraperitoneally with 50 mg/kg PDTC 1 hour before LPS treatment in the PDTC+LPS group. The mice in NS control group was given intraperitoneal injection of 0.1 mL NS only, and those in PDTC group was given intraperitoneal injection of 50 mg/kg PDTC only. The mice were sacrificed at 24 hours after model reproduction, and the lung tissues were harvested. The total antioxidant capacity (T-AOC) of lung tissue was measured by spectrophotometric kits. The content of malondialdehyde (MDA) was determined by thiobarbituric acid reactive substances assay. The protein expressions of superoxide dismutases (SOD1, SOD2) and catalase (CAT) in lung tissue were determined by Western Blot. Mitochondria from mouse lungs were isolated, and adenosine triphosphate (ATP) synthesis was measured with a luciferase/luciferin-based approach. The mitochondrial membrane potential (ΔΨm) was estimated by using Rhodamine. The mRNA expressions of mitochondrial uncoupling proteins (UCPs) were determined by reverse transcription-polymerase chain reaction (RT-PCR). LPS stimulation could significantly increase oxidative stress in lung tissue of mice and lead to mitochondrial dysfunction. The results showed that the protein expressions of T-AOC and SOD1 were decreased, the level of MDA was increased, the ATP synthesis was decreased in the mitochondrial, the ΔΨm was decreased, and the mRNA expression of UCP2 was decreased. However, there was no significant change in the expressions of SOD2, CAT in lung tissue and UCP1, UCP3 in the mitochondria. Pretreatment with PDTC could obviously alleviate the increase in LPS-induced oxidative stress in lung tissue and mitigate mitochondrial dysfunction. Compared with the LPS model group, T-AOC in lung tissue of PDTC+LPS group was significantly increased (U/g: 0.35±0.08 vs. 0.31±0.07), the level of MDA was significantly decreased (μmol/mg: 13.29±1.13 vs. 17.54±1.72), the protein expression of SOD1 was significantly upregulated (SOD1 protein: 1.13±0.11 vs. 0.71±0.09), ATP synthesis was significantly increased in the mitochondrial (μmol/mg: 49.23±5.42 vs. 36.92±2.21), ΔΨm was significantly increased (mV: 226.03±11.69 vs. 194.86±7.79), and the mRNA expression of UCP2 was significantly increased (2-ΔΔCt: 0.88±0.06 vs. 0.73±0.04). The differences were statistically significant (all P < 0.05). In lung tissue of normal mice, PDTC treatment also had the effect of anti-oxidizing, reducing oxidative stress and promoting ATP synthesis in the mitochondrial. Compared with the NS control group, the level of T-AOC (U/g: 0.49±0.09 vs. 0.43±0.06) and the protein expressions of SOD2 and CAT (SOD2 protein: 1.33±0.08 vs. 1.00±0.11, CAT protein: 1.39±0.08 vs. 1.00±0.11), and ATP synthesis in the mitochondrial of PDTC group was significantly increased (μmol/mg: 61.53±4.92 vs. 53.33±3.20), MDA was significantly decreased (μmol/mg: 10.27±1.25 vs. 12.27±1.36), with statistical differences, but had no effect on the protein expression of SOD1 in lung tissue and ΔΨm and UCPs mRNA expressions in mitochondrion. LPS can induce ALI in mice, increased oxidative stress in lung tissue, and induce mitochondrial dysfunction by inhibiting ATP synthesis. PDTC pretreatment has anti-oxidative effect on LPS-induced ALI, and can mitigate mitochondrial dysfunction.

β-Agonistic Bronchodilators: Comparison of Dose/Response in Working Rat Hearts

Using a mouse model of burn trauma, we tested the hypothesis that severe burn trauma corresponding to 30% of total body surface area (TBSA) causes reduction in adenosine triphosphate (ATP) synthesis in distal skeletal muscle. We employed in vivo 31P nuclear magnetic resonance (NMR) in intact mice to assess the rate of ATP synthesis, and characterized the concomitant gene expression patterns in skeletal muscle in burned (30% TBSA) versus control mice. Our NMR results showed a significantly reduced rate of ATP synthesis and were complemented by genomic results showing downregulation of the ATP synthase mitochondrial F1 F0 complex and PGC-1beta gene expression. Our findings suggest that inflammation and muscle atrophy in burns are due to a reduced ATP synthesis rate that may be regulated upstream by PGC-1beta. These findings implicate mitochondrial dysfunction in distal skeletal muscle following burn injury. That PGC-1beta is a highly inducible factor in most tissues and responds to common calcium and cyclic adenosine monophosphate (cAMP) signaling pathways strongly suggests that it may be possible to develop drugs that can induce PGC-1beta.

Leber hereditary optic neuropathy (LHON) is a maternally inherited form of central vision loss associated with mitochondrial DNA point mutations that affect the ND subunits of complex I. To elucidate the bioenergetic consequences of complex I dysfunction in LHON. The biochemical phenotypes of LHON mutations have been investigated using the transmitochondrial cytoplasmic hybrid (cybrid) cell model derived from the osteocarcoma parental cell line 143B.TK-. Research laboratories at neuroscience and biochemistry departments at the University of Bologna, Scientific Institute "E. Medea," and University of College Medical School. Fibroblast cell lines were obtained from patients affected with LHON, as defined by the presence of 1 pathogenic mutation, and from healthy volunteers as controls to construct cybrid cell lines. Complex I (glutamate-malate)- and complex II (succinate)-dependent adenosine triphosphate (ATP) synthesis, their respective respiratory rates, and total cellular ATP content were investigated using digitonin permeabilized cybrid cells. Multiple cybrid cell lines were constructed, introducing into osteosarcoma-derived rho(0) cells either wild-type or LHON mutant mitochondria carrying each of the 3 common mutations at positions 11778/ND4, 3460/ND1, and 14484/ND6. All 3 LHON mutations impaired ATP synthesis and the respiratory control ratio driven by complex I substrates. In contrast, succinate-driven ATP synthesis, respiration rates, and respiratory control ratios were not affected. However, the defective ATP synthesis with complex I substrates did not result in reduced ATP cellular content, indicating a compensatory mechanism. The LHON pathogenic mutations profoundly impair complex I-dependent synthesis of ATP, providing a common biochemical feature that may play a major role in LHON pathogenesis. Stratification of the results by mutation suggests that the 11778/ND4 mutation may induce an uncoupling of cybrid respiration, whereas the other 2 mutations impair the oxygen consumption rate.

Insulin-stimulated mitochondrial adenosine triphosphate synthesis is blunted in skeletal muscles of high-fat–fed rats

72] The use of K+ concentration gradients for the synthesis of ATP by mitochondria

The study aimed to explore the impact of a novel near-infrared LED (nNIR) with an extended spectrum on skin enhancement and hair growth. Various LED sources, including White and nNIRs, were compared across multiple parameters: cytotoxicity, adenosine triphosphate (ATP) synthesis, reactive oxygen species (ROS) reduction, skin thickness, collagen synthesis, collagenase expression, and hair follicle growth. Experiments were conducted on human skin cells and animal models. Cytotoxicity, ATP synthesis, and ROS reduction were evaluated in human skin cells exposed to nNIRs and Whites. LED irradiation effects were also studied on a UV-induced photoaging mouse model, analyzing skin thickness, collagen synthesis, and collagenase expression. Hair growth promotion was examined as well. Results revealed both White and nNIR were non-cytotoxic to human skin cells. nNIR enhanced ATP and collagen synthesis while reducing ROS levels, outperforming the commonly used 2chip LEDs. In the UV-induced photoaging mouse model, nNIR irradiation led to reduced skin thickness, increased collagen synthesis, and lowered collagenase expression. Additionally, nNIR irradiation stimulated hair growth, augmented skin thickness, and increased hair follicle count. In conclusion, the study highlighted positive effects of White and nNIR irradiation on skin and hair growth. However, nNIR exhibited superior outcomes compared to White. Its advancements in ATP content, collagen synthesis, collagenase inhibition, and hair growth promotion imply increased ATP synthesis activity. These findings underscore nNIR therapy’s potential as an innovative and effective approach for enhancing skin and promoting hair growth.

8 - Physiology of Mitochondria

In nonphotosynthetic organisms, mitochondria are the power plant of the cell, emphasizing their great potentiality for adenosine triphosphate (ATP) synthesis from the redox span between nutrients and oxygen. Also of great importance is their role in the maintenance of the cell redox balance. Even though crystallographic structures of respiratory complexes, ATP synthase, and ATP/adenosine diphosphate (ADP) carrier are now quite well known, the coupling between ATP synthesis and cell redox state remains a controversial issue. In this review, we will present some of the processes that allow a modular coupling between ATP synthesis and redox state. Furthermore, we will present some theoretical approaches of this highly integrated system.

The energies of electron transfer between pyrophosphate metal complexes and hydrated metal complexes, which is the key reaction that models the radical ion mechanism of adenosine triphosphate (ATP) synthesis, were calculated. A threshold dependence of the energy on the number of water molecules n in the ion hydration sphere was established: for n < 4 the reaction is exothermic, while for n ≥ 4 it is endothermic. The switching of the energy regime accounts for the fact that ATP is synthesized only in molecular machines, enzymes, rather than in homogeneous aqueous solutions. It was predicted theoretically that the radical ion ATP synthesis may be catalyzed by not only magnesium ions as in living cells but also by calcium, zinc, barium, cadmium, and tin ions. This prediction was experimentally confirmed by the discovery of the magnetic isotope effect in the calcium- and zinc-catalyzed ATP synthesis by creatine kinase. The efficiency of ATP synthesis in the presence of ions with magnetic nuclei 43Ca and 67Zn is almost twice as high as that in the presence of the same ions with nonmagnetic nuclei 40Ca and 64Zn.