Cell Biology of the Mitochondrion.

Mitochondria are best known for harboring pathways involved in ATP synthesis through the tricarboxylic acid cycle and oxidative phosphorylation. Major advances in understanding these roles were made with mutants affecting key components of the metabolic pathways. These mutants have not only helped elucidate some of the intricacies of metabolism pathways, but they have also served as jumping off points for pharmacology, toxicology, and aging studies.

Tether mutations that restore function and suppress pleiotropic phenotypes of the C. elegans isp-1(qm150) Rieske iron-sulfur protein.

Mitochondria play an important role in numerous diseases as well as normative aging. Severe reduction in mitochondrial function contributes to childhood disorders such as Leigh Syndrome, whereas mild disruption can extend the lifespan of model organisms. The Caenorhabditis elegans isp-1 gene encodes the Rieske iron-sulfur protein subunit of cytochrome c oxidoreductase (complex III of the electron transport chain).

Propofol compared with isoflurane inhibits mitochondrial metabolism in immature swine cerebral cortex.

Anesthetics used in infants and children are implicated in the development of neurocognitive disorders. Although propofol induces neuroapoptosis in developing brain, the underlying mechanisms require elucidation and may have an energetic basis. We studied substrate utilization in immature swine anesthetized with either propofol or isoflurane for 4 hours.

The role of DMQ(9) in the long-lived mutant clk-1.

Introduction: Ubiquinone (UQ) is a redox active lipid that transfers electrons from complex I or II to complex III in the electron transport chain (ETC). The long-lived Caenorhabditis elegans mutant clk-1 is unable to synthesize its native ubiquinone, and accumulates high amounts of its precursor, 5-demethoxyubiquinone-9 (DMQ(9)). In clk-1, complexes I-III activity is inhibited while complexes II-III activity is normal.

Isoflurane selectively inhibits distal mitochondrial complex I in Caenorhabditis elegans.

Background: Complex I of the electron transport chain (ETC) is a possible target of volatile anesthetics (VAs). Complex I enzymatic activities are inhibited by VAs, and dysfunction of complex I can lead to hypersensitivity to VAs in worms and in people. Mutant analysis in Caenorhabditis (C.

Mutations in mitochondrial complex III uniquely affect complex I in Caenorhabditis elegans.

Mitochondrial supercomplexes containing complexes I, III, and IV of the electron transport chain are now regarded as an established entity. Supercomplex I·III·IV has been theorized to improve respiratory chain function by allowing quinone channeling between complexes I and III. Here, we show that the role of the supercomplexes extends beyond channeling.

Alternatives to mammalian pain models 1: use of C. elegans for the study of volatile anesthetics.

Performing genetic studies in model organisms is a powerful approach for investigating the mechanisms of volatile anesthetic action. Striking similarities between the results observed in Caenorhabditis elegans and in other organisms suggest that many of the conclusions can be generalized across disparate phyla, and that findings in these model organisms will be applicable in humans. In this chapter, we provide detailed protocols for working with C.

Subcomplex Ilambda specifically controls integrated mitochondrial functions in Caenorhabditis elegans.

Complex I dysfunction is a common, heterogeneous cause of human mitochondrial disease having poorly understood pathogenesis. The extensive conservation of complex I composition between humans and Caenorhabditis elegans permits analysis of individual subunit contribution to mitochondrial functions at both the whole animal and mitochondrial levels. We provide the first experimentally-verified compilation of complex I composition in C.

The effect of different ubiquinones on lifespan in Caenorhabditis elegans.

Ubiquinone (UQ, Coenzyme Q, CoQ) transfers electrons from complexes I and II to complex III in the mitochondrial electron transport chain. Depending on the degree of reduction, UQ can act as either a pro- or an antioxidant. Mutations disrupting ubiquinone synthesis increase lifespan in both the nematode (clk-1) and the mouse (mclk-1).

Complex I function is defective in complex IV-deficient Caenorhabditis elegans.

Cytochrome c oxidase (COX) is hypothesized to be an important regulator of oxidative phosphorylation. However, no animal phenotypes have been described due to genetic defects in nuclear-encoded subunits of COX. We knocked down predicted homologues of COX IV and COX Va in the nematode Caenorhabditis elegans.

Sulfated signal from ASJ sensory neurons modulates stomatin-dependent coordination in Caenorhabditis elegans.

The neuronal stomatin-like proteins UNC-1 and UNC-24 play important roles in the nervous system of Caenorhabditis elegans. These neuronal stomatin-like proteins are putative chaperone proteins that can modify volatile anesthetic sensitivity and disrupt coordinated locomotion. A suppressor of unc-1 and unc-24, named ssu-1(fc73) (for suppressor of stomatin uncoordination), suppresses three phenotypes of neuronal stomatin-like protein deficiency as follows: volatile anesthetic sensitivity, uncoordinated locomotion, and a constitutive alternative developmental phenotype known as dauer.

Tail clamp responses in stomatin knockout mice compared with mobility assays in Caenorhabditis elegans during exposure to diethyl ether, halothane, and isoflurane.

Background: The gene unc-1 plays a central role in determining volatile anesthetic sensitivity in Caenorhabditis elegans. Because different unc-1 alleles cause strikingly different phenotypes in different volatile anesthetics, the UNC-1 protein is a candidate to directly interact with volatile anesthetics. UNC-1 is a close homologue of the mammalian protein stomatin, for which a mouse knockout was recently constructed.

Mitochondrial complex I function affects halothane sensitivity in Caenorhabditis elegans.

Background: : The gene gas-1 encodes a subunit of complex I of the mitochondrial electron transport chain in Caenorhabditis elegans. A mutation in gas-1 profoundly increases sensitivity of C. elegans to volatile anesthetics.

Mitochondrial oxidative phosphorylation is defective in the long-lived mutant clk-1.

The long-lived mutant of Caenorhabditis elegans, clk-1, is unable to synthesize ubiquinone, CoQ(9). Instead, the mutant accumulates demethoxyubiquinone(9) and small amounts of rhodoquinone(9) as well as dietary CoQ(8). We found a profound defect in oxidative phosphorylation, a test of integrated mitochondrial function, in clk-1 mitochondria fueled by NADH-linked electron donors, i.

The effects of complex I function and oxidative damage on lifespan and anesthetic sensitivity in Caenorhabditis elegans.

A mutation in a subunit of complex I of the mitochondrial electron transport chain (gas-1) causes Caenorhabditis elegans to be hypersensitive to volatile anesthetics and oxygen as well as shortening lifespan. We hypothesized that changes in mitochondrial respiration or reactive oxygen species production cause these changes. Therefore, we compared gas-1 to other mitochondrial mutants to identify the relative importance of these two aspects of mitochondrial function in determining longevity.

A mutation in mitochondrial complex I increases ethanol sensitivity in Caenorhabditis elegans.

Background: The gene gas-1 encodes the 49-kDa subunit of complex I of the mitochondrial electron transport chain in Caenorhabditis elegans. A mutation in gas-1 profoundly increases sensitivity to ethanol and decreases complex I-dependent metabolism in mitochondria.

Methods: Mitochondria were isolated from wild-type and gas-1 strains of C.

Understanding anesthesia: making genetic sense of the absence of senses.

The discovery of the phenomenon of anesthesia over 150 years ago was a watershed event that revolutionized the practice of medicine. Despite their annual use in millions of patients, the mechanism by which volatile anesthetics produce reversible loss of consciousness remains a mystery. The inherent problems in studying loss of consciousness in humans are legion.