scholarly journals Evidence of Oxidative Phosphorylation in Zebrafish Photoreceptor Outer Segments at Different Larval Stages

2018 ◽  
Vol 66 (7) ◽  
pp. 497-509 ◽  
Author(s):  
Daniela Calzia ◽  
Greta Garbarino ◽  
Federico Caicci ◽  
Mario Pestarino ◽  
Lucia Manni ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Aerobic Metabolism ◽  
Respiratory Chain Complexes ◽  
Atp Production ◽  
Photoreceptor Outer Segments ◽  
Larval Stages ◽  
Outer Segments ◽  
Chain Complexes ◽  
Transmission Electron

Summary Previous studies on purified bovine rod outer segments (OS) disks pointed to Oxidative Phosphorylation (OXPHOS) as being the most likely mechanism involved in ATP production, as yet not fully understood, to support the first phototransduction steps. Bovine and murine rod OS disks, devoid of mitochondria, would house respiratory chain complexes I to IV and ATP synthase, similar to mitochondria. Zebrafish ( Danio rerio) is a well-suited animal model to study vertebrate embryogenesis as well as the retina, morphologically and functionally similar to its human counterpart. The present article reports fluorescence and Transmission Electron Microscopy colocalization analyses of respiratory complexes I and IV and ATP synthase with zpr3, the rod OS marker, in adult and larval zebrafish retinas. MitoTracker Deep Red 633 staining and assays of complexes I and III–IV activity suggest that those proteins are active in OS. Results show that an extramitochondrial aerobic metabolism is active in the zebrafish OS at 4 and 10 days of larval development, as well as in adults, suggesting that it is probably maintained during embryogenesis. Data support the hypothesis of an extramitochondrial aerobic metabolism in the OS of zebrafish.

scholarly journals Oxidative phosphorylation is required for powering motility and development of the sleeping sickness parasite Trypanosoma brucei within the tsetse fly vector

2021 ◽  
Author(s):  
Caroline E Dewar ◽  
Aitor Casas-Sánchez ◽  
Constentin Dieme ◽  
Aline Crouzols ◽  
Lee Haines ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Trypanosoma Brucei ◽  
Atp Synthase ◽  
Sleeping Sickness ◽  
Tsetse Fly ◽  
Tsetse Flies ◽  
Respiratory Chain Complexes ◽  
Atp Production

The single-celled parasite Trypanosoma brucei causes sleeping sickness in humans and nagana in livestock and is transmitted by hematophagous tsetse flies. Lifecycle progression from mammalian bloodstream form to tsetse midgut form and, subsequently, infective salivary gland form depends on complex developmental steps and migration within different fly tissues. As the parasite colonises the glucose-poor insect midgut, its ATP production is thought to depend on activation of mitochondrial amino acid catabolism via oxidative phosphorylation. This process involves respiratory chain complexes and the F1FO-ATP synthase, and it requires protein subunits of these complexes that are encoded in the parasite's mitochondrial DNA (kinetoplast or kDNA). Here we show that a progressive loss of kDNA-encoded functions correlates with an increasingly impaired ability of T. brucei to initiate and complete its development in the tsetse. First, parasites with a mutated F1FO-ATP synthase with a reduced capacity for oxidative phosphorylation can initiate differentiation from bloodstream to insect form, but they are unable to proliferate in vitro. Unexpectedly, these cells can still colonise the tsetse midgut. However, these parasites exhibit a motility defect and are severely impaired in colonising or migrating to subsequent tsetse tissues. Second, parasites with a fully disrupted F1FO-ATP synthase complex that is completely unable to produce ATP by oxidative phosphorylation can still differentiate to the first insect stage in vitro but die within a few days and cannot establish a midgut infection in vivo. Third, mutant parasites lacking kDNA entirely can initiate differentiation but die within 24 h. Together, these three scenarios show that efficient ATP production via oxidative phosphorylation is not essential for initial colonisation of the tsetse vector, but it is required to power trypanosome migration within the fly.

Dual Mutations Reveal Interactions Between Components of Oxidative Phosphorylation in Kluyveromyces lactis

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 929-938
Author(s):  
G D Clark-Walker ◽  
X J Chen
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Kluyveromyces Lactis ◽  
Mitochondrial Protein ◽  
Proton Pumping ◽  
Nuclear Genes ◽  
Suppressor Activity ◽  
Inner Membrane ◽  
Atp Production

Abstract Loss of mtDNA or mitochondrial protein synthesis cannot be tolerated by wild-type Kluyveromyces lactis. The mitochondrial function responsible for ρ0-lethality has been identified by disruption of nuclear genes encoding electron transport and F0-ATP synthase components of oxidative phosphorylation. Sporulation of diploid strains heterozygous for disruptions in genes for the two components of oxidative phosphorylation results in the formation of nonviable spores inferred to contain both disruptions. Lethality of spores is thought to result from absence of a transmembrane potential, ΔΨ, across the mitochondrial inner membrane due to lack of proton pumping by the electron transport chain or reversal of F1F0-ATP synthase. Synergistic lethality, caused by disruption of nuclear genes, or ρ0-lethality can be suppressed by the atp2.1 mutation in the β-subunit of F1-ATPase. Suppression is viewed as occurring by an increased hydrolysis of ATP by mutant F1, allowing sufficient electrogenic exchange by the translocase of ADP in the matrix for ATP in the cytosol to maintain ΔΨ. In addition, lethality of haploid strains with a disruption of AAC encoding the ADP/ATP translocase can be suppressed by atp2.1. In this case suppression is considered to occur by mutant F1 acting in the forward direction to partially uncouple ATP production, thereby stimulating respiration and relieving detrimental hyperpolarization of the inner membrane. Participation of the ADP/ATP translocase in suppression of ρ0-lethality is supported by the observation that disruption of AAC abolishes suppressor activity of atp2.1.

Improvement in the efficiency of oxidative phosphorylation in the freshwater eel acclimated to 10.1 MPa hydrostatic pressure

2000 ◽  
Vol 203 (19) ◽  
pp. 3019-3023
Author(s):  
M. Theron ◽  
F. Guerrero ◽  
P. Sebert
Keyword(s):  
Hydrostatic Pressure ◽  
Oxidative Phosphorylation ◽  
Atmospheric Pressure ◽  
High Hydrostatic Pressure ◽  
Anguilla Anguilla ◽  
Respiratory Chain Complexes ◽  
Complex Iv ◽  
Control Value ◽  
Chain Complexes ◽  
Freshwater Eel

Previous studies have suggested that the efficiency of oxidative phosphorylation in the freshwater eel (Anguilla anguilla) is increased after acclimation to high hydrostatic pressure. Analysis at atmospheric pressure of the respiratory chain complexes showed that, after 21 days at 10.1 MPa, the activity of complex II was decreased to approximately 50 % (P<0.01) of the control value and that cytochrome c oxidase (complex IV) activity was significantly increased to 149 % of the control value (P<0.05). ADP/O ratios calculated from mitochondrial respiration measurements were significantly increased after acclimation to high hydrostatic pressure (2.87 versus 2.52, P<0.001) when measured in the presence of pyruvate plus malate at atmospheric pressure. These results clearly show an increased oxidative phosphorylation efficiency in response to high-pressure acclimation.

Physiological diversity of mitochondrial oxidative phosphorylation

2006 ◽  
Vol 291 (6) ◽  
pp. C1172-C1182 ◽  
Author(s):  
G. Benard ◽  
B. Faustin ◽  
E. Passerieux ◽  
A. Galinier ◽  
C. Rocher ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Respiratory Chain ◽  
Citrate Synthase ◽  
Intrinsic Activity ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Respiratory Chain Complexes ◽  
Mitochondrial Content ◽  
Physiological Diversity ◽  
Chain Complexes ◽  
Functional Features

To investigate the physiological diversity in the regulation and control of mitochondrial oxidative phosphorylation, we determined the composition and functional features of the respiratory chain in muscle, heart, liver, kidney, and brain. First, we observed important variations in mitochondrial content and infrastructure via electron micrographs of the different tissue sections. Analyses of respiratory chain enzyme content by Western blot also showed large differences between tissues, in good correlation with the expression level of mitochondrial transcription factor A and the activity of citrate synthase. On the isolated mitochondria, we observed a conserved molar ratio between the respiratory chain complexes and a variable stoichiometry for coenzyme Q and cytochrome c, with typical values of [1–1.5]:[30–135]:[3]:[9–35]:[6.5–7.5] for complex II:coenzyme Q:complex III:cytochrome c:complex IV in the different tissues. The functional analysis revealed important differences in maximal velocities of respiratory chain complexes, with higher values in heart. However, calculation of the catalytic constants showed that brain contained the more active enzyme complexes. Hence, our study demonstrates that, in tissues, oxidative phosphorylation capacity is highly variable and diverse, as determined by different combinations of 1) the mitochondrial content, 2) the amount of respiratory chain complexes, and 3) their intrinsic activity. In all tissues, there was a large excess of enzyme capacity and intermediate substrate concentration, compared with what is required for state 3 respiration. To conclude, we submitted our data to a principal component analysis that revealed three groups of tissues: muscle and heart, brain, and liver and kidney.

Bupivacaine uncouples the mitochondrial oxidative phosphorylation, inhibits respiratory chain complexes I and III and enhances ROS production: Results of a study on cell cultures

Mitochondrion ◽  
2010 ◽  
Vol 10 (5) ◽  
pp. 487-496 ◽  
Author(s):  
Olga Cela ◽  
Claudia Piccoli ◽  
Rosella Scrima ◽  
Giovanni Quarato ◽  
Alessandra Marolla ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Respiratory Chain ◽  
Cell Cultures ◽  
Ros Production ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Respiratory Chain Complexes ◽  
Chain Complexes

scholarly journals The ADP/ATP Carrier and Its Relationship to Oxidative Phosphorylation in Ancestral Protist Trypanosoma brucei

2015 ◽  
Vol 14 (3) ◽  
pp. 297-310 ◽  
Author(s):  
Anna Gnipová ◽  
Karolína Šubrtová ◽  
Brian Panicucci ◽  
Anton Horváth ◽  
Julius Lukeš ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Trypanosoma Brucei ◽  
Atp Synthesis ◽  
Model Organisms ◽  
Growth Defect ◽  
Respiratory Chain Complexes ◽  
Content Type ◽  
Chain Complexes ◽  
Parasitic Protist ◽  
Veterinary Importance

ABSTRACT The highly conserved ADP/ATP carrier (AAC) is a key energetic link between the mitochondrial (mt) and cytosolic compartments of all aerobic eukaryotic cells, as it exchanges the ATP generated inside the organelle for the cytosolic ADP. Trypanosoma brucei , a parasitic protist of medical and veterinary importance, possesses a single functional AAC protein (TbAAC) that is related to the human and yeast ADP/ATP carriers. However, unlike previous studies performed with these model organisms, this study showed that TbAAC is most likely not a stable component of either the respiratory supercomplex III+IV or the ATP synthasome but rather functions as a physically separate entity in this highly diverged eukaryote. Therefore, TbAAC RNA interference (RNAi) ablation in the insect stage of T. brucei does not impair the activity or arrangement of the respiratory chain complexes. Nevertheless, RNAi silencing of TbAAC caused a severe growth defect that coincides with a significant reduction of mt ATP synthesis by both substrate and oxidative phosphorylation. Furthermore, TbAAC downregulation resulted in a decreased level of cytosolic ATP, a higher mt membrane potential, an elevated amount of reactive oxygen species, and a reduced consumption of oxygen in the mitochondria. Interestingly, while TbAAC has previously been demonstrated to serve as the sole ADP/ATP carrier for ADP influx into the mitochondria, our data suggest that a second carrier for ATP influx may be present and active in the T. brucei mitochondrion. Overall, this study provides more insight into the delicate balance of the functional relationship between TbAAC and the oxidative phosphorylation (OXPHOS) pathway in an early diverged eukaryote.

scholarly journals Chemiosmotic coupling in oxidative phosphorylation: The history of a hard experimental effort hampered by the Heisenberg indeterminacy principle

2018 ◽  
Author(s):  
Alessandro Maria Morelli ◽  
Silvia Ravera ◽  
Daniela Calzia ◽  
Isabella Panfoli
Keyword(s):  
Oxidative Phosphorylation ◽  
Proton Translocation ◽  
Structural Data ◽  
Biological Research ◽  
Proton Pumps ◽  
Chemiosmotic Theory ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
Definition Of ◽  
Chemiosmotic Coupling

Understanding how biological systems convert and store energy is a primary goal of biological research. However, despite the formulation of Mitchell’s chemiosmotic theory, which allowed taking fundamental steps forward, we are still far from the complete decryption of basic processes as oxidative phosphorylation (OXPHOS) and photosynthesis. After more than half a century, the chemiosmotic theory appears to need updating, as some of its assumptions have proven incorrect in the light of the latest structural data on respiratory chain complexes, bacteriorhodopsin and proton pumps. Moreover, the existence of an OXPHOS on the plasma membrane of cells casts doubt on the possibility to build up a transversal proton gradient across it, while paving the way for important applications in the field of neurochemistry and oncology. Up-to date biotechnologies, such as fluorescence indicators can follow proton displacement and sinks, and a number of reports have elegantly demonstrated that proton translocation is lateral rather than transversal with respect to the coupling membrane. Furthermore, the definition of the physical species involved in the transfer (proton, hydroxonium ion or proton currents) is still unresolved even though the latest acquisitions support the idea that protonic currents, difficult to measure, are involved. It seems that the concept of diffusion of the proton expressed more than two centuries ago by Theodor von Grotthuss, is decisive for overcoming these issues. All these uncertainties remember us that also in biology it is necessary to take into account the Heisenberg indeterminacy principle, that sets limits to analytical questions.

Tracking protons from respiratory chain complexes to ATP synthase c -subunit: The critical role of serine and threonine residues

2017 ◽  
Vol 482 (4) ◽  
pp. 922-927 ◽  
Author(s):  
Isabella Panfoli ◽  
Marco Ponassi ◽  
Silvia Ravera ◽  
Daniela Calzia ◽  
Maider Beitia ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Atp Synthase ◽  
Critical Role ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
C Subunit

scholarly journals Cytotoxicity of mitochondria-targeted resveratrol derivatives: Interactions with respiratory chain complexes and ATP synthase

2014 ◽  
Vol 1837 (10) ◽  
pp. 1781-1789 ◽  
Author(s):  
Nicola Sassi ◽  
Andrea Mattarei ◽  
Michele Azzolini ◽  
Ildiko' Szabo' ◽  
Cristina Paradisi ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Atp Synthase ◽  
Respiratory Chain Complexes ◽  
Chain Complexes ◽  
Resveratrol Derivatives
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