Effect of bilirubin on cytochrome c oxidase activity of mitochondria from mouse brain and liver

<p>Abstract</p> <p>Background</p> <p>The unbound, free concentration (B_f) of unconjugated bilirubin (UCB), and not the total UCB level, has been shown to correlate with bilirubin cytotoxicity, but the key molecular mechanisms accounting for the toxic effects of UCB are largely unknown.</p> <p>Findings</p> <p>Mouse liver mitochondria increase unbound UCB oxidation, consequently increasing the apparent rate constant for unbound UCB oxidation by HRP (Kp), higher than in control and mouse brain mitochondria, emphasizing the importance of determining Kp in complete systems containing the organelles being studied. The <it>in vitro </it>effects of UCB on cytochrome <it>c </it>oxidase activity in mitochondria isolated from mouse brain and liver were studied at B_franging from 22 to 150 nM. The results show that UCB at B_fup to 60 nM did not alter mitochondrial cytochrome <it>c </it>oxidase activity, while the higher concentrations significantly inhibited the enzyme activity by 20% in both liver and brain mitochondria.</p> <p>Conclusions</p> <p>We conclude that it is essential to include the organelles being studied in the medium used in measuring both Kp and B_f. A moderately elevated, pathophysiologically-relevant B_fimpaired the cytochrome <it>c </it>oxidase activity modestly in mitochondria from mouse brain and liver.</p

The effect of 5-aminolevulinic acid on cytochrome c oxidase activity in mouse liver

<p>Abstract</p> <p>Background</p> <p>5-Aminolevulinic acid (ALA) is a precursor of heme that is fundamentally important in aerobic energy metabolism. Among the enzymes involved in aerobic energy metabolism, cytochrome <it>c </it>oxidase (COX) is crucial. In this study, the effect of ALA on cytochrome <it>c </it>oxidase activity was measured.</p> <p>Findings</p> <p>c57BL/6N species of mice were administered ALA orally for 15 weeks. After ALA administration, mice were sacrificed and livers were obtained. COX activity in mitochondria from ALA-administered mouse livers was 1.5-fold higher than that in mitochondria from PBS-administered mouse livers (P < 0.05). Furthermore, ATP levels in ALA-administered mouse livers were much higher than those in PBS-administered mouse livers. These data suggest that oral administration of ALA promotes aerobic energy metabolism, especially COX activity.</p> <p>Conclusions</p> <p>This is the first report of a drug that functions in aerobic energy metabolism directly. Since COX activity is decreased in various diseases and aging, the pharmacological effects of ALA will be expanding.</p

Mathematical Modeling of the Role of Mitochondrial Fusion and Fission in Mitochondrial DNA Maintenance

10.1371/journal.pone.0076230PLOS ONE8101-1

Symptoms of Anxiety, Depression, and Aggression in Non-clinical Children: Relationships with Self-report and Performance-based Measures of Attention and Effortful Control

This study investigated the relation between the regulative trait of effortful control, and in particular attention control, and psychopathological symptoms in a sample of 207 non-clinical children aged 8–12 years. For this purpose, children completed self-report scales for measuring regulative traits and various types of psychopathological symptoms (i.e., anxiety, depression, and aggression) and were tested with a neuropsychological battery for measuring attention/effortful control capacity. Results indicated that self-report and performance-based measures of attention/effortful control were at best moderately correlated. Further, it was found that self-report indexes of attention/effortful control were clearly negatively related to psychopathological symptoms, which provides support for the notion that low regulation is associated with higher levels of psychopathology. Finally, the performance-based measure of attention/effortful control was not convincingly related to psychopathological symptoms

Large-Range Movements of Neotropical Orchid Bees Observed via Radio Telemetry

Neotropical orchid bees (Euglossini) are often cited as classic examples of trapline-foragers with potentially extensive foraging ranges. If long-distance movements are habitual, rare plants in widely scattered locations may benefit from euglossine pollination services. Here we report the first successful use of micro radio telemetry to track the movement of an insect pollinator in a complex and forested environment. Our results indicate that individual male orchid bees (Exaerete frontalis) habitually use large rainforest areas (at least 42–115 ha) on a daily basis. Aerial telemetry located individuals up to 5 km away from their core areas, and bees were often stationary, for variable periods, between flights to successive localities. These data suggest a higher degree of site fidelity than what may be expected in a free living male bee, and has implications for our understanding of biological activity patterns and the evolution of forest pollinators

Biogenesis and Dynamics of Mitochondria during the Cell Cycle: Significance of 3′UTRs

Nowadays, we are facing a renaissance of mitochondria in cancer biology. However, our knowledge of the basic cell biology and on the timing and mechanisms that control the biosynthesis of mitochondrial constituents during progression through the cell cycle of mammalian cells remain largely unknown. Herein, we document the in vivo changes on mitochondrial morphology and dynamics that accompany cellular mitosis, and illustrate the following key points of the biogenesis of mitochondria during progression of liver cells through the cycle: (i) the replication of nuclear and mitochondrial genomes is synchronized during cellular proliferation, (ii) the accretion of OXPHOS proteins is asynchronously regulated during proliferation being the synthesis of β-F1-ATPase and Hsp60 carried out also at G2/M and, (iii) the biosynthesis of cardiolipin is achieved during the S phase, although full development of the mitochondrial membrane potential (ΔΨm) is attained at G2/M. Furthermore, we demonstrate using reporter constructs that the mechanism regulating the accretion of β-F1-ATPase during cellular proliferation is controlled at the level of mRNA translation by the 3′UTR of the transcript. The 3′UTR-driven synthesis of the protein at G2/M is essential for conferring to the daughter cells the original phenotype of the parental cell. Our findings suggest that alterations on this process may promote deregulated β-F1-ATPase expression in human cancer

Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems.Portuguese funds from FCT - Foundation for Science and Technology [UID/Multi/04326/2013]; SZN PhD fellowship via the Open University; ESF COST Action Seagrass Productivity: From Genes to Ecosystem Management [ES0906]info:eu-repo/semantics/publishedVersio

Mitochondrial ATP synthase: architecture, function and pathology

Human mitochondrial (mt) ATP synthase, or complex V consists of two functional domains: F1, situated in the mitochondrial matrix, and Fo, located in the inner mitochondrial membrane. Complex V uses the energy created by the proton electrochemical gradient to phosphorylate ADP to ATP. This review covers the architecture, function and assembly of complex V. The role of complex V di-and oligomerization and its relation with mitochondrial morphology is discussed. Finally, pathology related to complex V deficiency and current therapeutic strategies are highlighted. Despite the huge progress in this research field over the past decades, questions remain to be answered regarding the structure of subunits, the function of the rotary nanomotor at a molecular level, and the human complex V assembly process. The elucidation of more nuclear genetic defects will guide physio(patho)logical studies, paving the way for future therapeutic interventions