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PubMed1986

Quantitation of mitochondrial RNA species during rat liver development: the concentration of cytochrome oxidase subunit I (CoI) mRNA increases at birth.

A quantitative study on the concentration of mitochondrial DNA and two species of mtRNA, the ribosomal (16S rRNA) and messenger (CoI mRNA) has been carried out in rat liver between -3 and 14 days of age. The cellular content of mitochondrial DNA begins to increase at one day of life and goes up linearly until 14 days of age. The cellular level of 16S rRNA and CoI mRNA changes during development: the 16S rRNA increases linearly after birth, whereas CoI mRNA shows a peak at birth and thereafter remains more or less constant. The concentration of 16S rRNA per mitochondrial DNA molecule remains substantially unchanged during development, whereas that of CoI mRNA increases before birth and, at birth, reaches values higher than in adults. These results support an independent regulation of mitochondrial rRNA and mRNA level in rat liver mitochondria during development.

Animals↗
PubMed1990

Kinetoplast DNA minicircles encode guide RNAs for editing of cytochrome oxidase subunit III mRNA.

Guide RNAs (gRNAs) for the editing of sites 1-8 of COIII mRNA and an "unexpected" partially edited COIII mRNA are encoded in the variable regions of specific kinetoplast DNA minicircles. The gRNAs can form 37 and 44 nucleotide perfect hybrids (allowing for G-U base pairs) with edited mRNAs. The gRNAs were detected on Northern blots and shown to have unique 5' ends situated close to the beginning of the potential base pairing with the edited mRNAs. We suggest that kinetoplast DNA minicircle molecules in general may encode gRNAs for editing of cryptogene mRNAs by a mechanism similar to that previously proposed for editing by maxicircle-encoded gRNAs.

Animals↗
PubMed1995

Electron transfer and proton pumping in cytochrome oxidase.

This article presents an outlook on the structure and function of terminal oxidases, the respiratory enzymes which catalyze the reduction of dioxygen to water in aerobic organisms. The structure of the redox active metals, their interactions with the protein matrix, and their role in electron transfer ligand binding and proton pumping are briefly reviewed.

Amino Acid Sequence↗
PubMed1994

The cytochrome oxidase superfamily of redox-driven proton pumps.

Most respiratory oxidases of eukaryotic and prokaryotic organisms are members of a superfamily of enzymes that couple the redox energy available from the reduction of molecular oxygen to the mechanism of pumping protons across the membrane. The recent applications of site-directed mutagenesis and of a variety of spectroscopic techniques have allowed major advances in our understanding of the structure and function of these proteins.

Amino Acid Sequence↗
PubMed2005

Resistance exercise training decreases oxidative damage to DNA and increases cytochrome oxidase activity in older adults.

Regular resistance exercise increases muscle strength and induces muscle fibre hypertrophy in older adults. Although the underlying causes of aging remain unclear, like acute exercise, aging is associated with oxidative stress. In ageing, however, oxidative stress is closely associated with mitochondrial dysfunction as proposed by the mitochondrial theory of aging. The effect of regular resistance exercise upon mitochondrial function and oxidative stress in older adults is unknown. Twenty-eight older men and women (approximately 68.5+/-5.1 yr) performed whole-body resistance exercise training for 14 weeks. Muscle biopsies were taken before and 72 h following the last exercise bout from the vastus lateralis. Urine samples were also taken at the time of tissue collection. Resistance exercise training was associated with a decrease in 8-OHdG (Pre: 10783+/-5856, Post: 8897+/-4030 ng g(-1) creatinine; p<0.05). Protein content for CuZnSOD, MnSOD, and catalase, and enzyme activities for citrate synthase, mitochondrial ETC complex I+III, and complex II+III were not significantly different from baseline. However, complex IV activity was significantly higher after training as compared to before training (Pre: 2.2+/-0.5, Post: 2.9+/-0.9 micromol min(-1) g(-1)ww; p<0.05), as was the ratio of complex IV to complex I (Pre: 11.1+/-9.3, Post: 14.5+/-10.3; p<0.05). There were no apparent changes in normal mtDNA content or visible mtDNA deletion products as a function of training. These data suggest that regular resistance exercise decreases oxidative stress, but does not affect mtDNA. Moreover, increases in complex IV of the electron transport chain may have an indirect antioxidant effect in older adults and may improve function in daily activities.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

Phylogeny and molecular evolution of the tribe Harpalini (Coleoptera, Carabidae) inferred from mitochondrial cytochrome-oxidase I.

The tribe Harpalini is a group of ground beetles with a world-wide distribution that comprises approximately 2000 species and about 238 genera and subgenera. Hypotheses about the phylogenetic relationships of the subtribes of Harpalini are implicit within the systematic criteria put forward by different authors. A 759 bp fragment of the mitochondrial COI was sequenced in 119 specimens (107 species) of 52 genera and subgenera that represent the main lineages of Harpalines, and 3 species of other tribes used as outgroups. A hierarchical study of sequence divergence (under uncorrected and corrected models) and ts:tv ratio pattern analyses were carried out at different taxonomic levels. A low saturation rate was detected at first and second codon positions, whereas A+T richness causes a low transitions:transversions ratio, which suggests--a priori--a high rate of saturation at the third codon position. A progressive accumulation of sequence divergence and a decreasing ts:tv ratio were found from lower to higher taxonomic levels. MP strict consensus, ML, and minimum evolution distance (under ts+tv and tv only schemes) trees showed similar major clades within the tribe. The subtribe Ditomina is a monophyletic lineage with close affinities to the subtribe Harpalina. Harpalina is a polyphyletic lineage as the genus Daptus is always related to members of the subtribe Stenolophina, and the Selenophorines resulted a polyphyletic group related to the subtribe Anisodactylina. Main lineages proposed by Noonan [Quaest. Entomol. 9 (1973) 266] within the subtribe Anisodactylina have been corroborated in this study. The Australian genus Phorticosomus is not related to Ditomina but to the Australian Notiobioids lineage. Most taxa of the subtribe Stenolophina are always included in the same clade, together with taxa of the subtribe Pelmatellina, which might be considered as a lineage of Stenolophina related to Bradycellus and Dicheirotrichus. The subtribe Amblystomina lacks a well-supported relationship to the other subtribes of Harpalini and could not be consistently related to any of them.

Animals↗