scholarly journals Normal Levels of Wild-Type Mitochondrial DNA Maintain Cytochrome c Oxidase Activity for Two Pathogenic Mitochondrial DNA Mutations but Not for m.3243A→G

2007 ◽  
Vol 81 (1) ◽  
pp. 189-195 ◽  
Author(s):  
Steve E. Durham ◽  
David C. Samuels ◽  
Lynsey M. Cree ◽  
Patrick F. Chinnery
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Wild Type ◽  
Mitochondrial Dna Mutations ◽  
Dna Mutations

scholarly journals Induction and characterization of mitochondrial DNA mutants in Chlamydomonas reinhardtii.

1989 ◽  
Vol 108 (4) ◽  
pp. 1221-1226 ◽  
Author(s):  
R F Matagne ◽  
M R Michel-Wolwertz ◽  
C Munaut ◽  
C Duyckaerts ◽  
F Sluse
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Chlamydomonas Reinhardtii ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Wild Type ◽  
Apocytochrome B ◽  
Cytochrome Pathway ◽  
Apocytochrome B Gene

In addition to lethal minute colony mutations which correspond to loss of mitochondrial DNA, acriflavin induces in Chlamydomonas reinhardtii a low percentage of cells that grow in the light but do not divide under heterotrophic conditions. Two such obligate photoautotrophic mutants were shown to lack the cyanide-sensitive cytochrome pathway of the respiration and to have a reduced cytochrome c oxidase activity. In crosses to wild type, the mutations are transmitted almost exclusively from the mating type minus parent. A same pattern of inheritance is seen for the mitochondrial DNA in crosses between the two interfertile species C. reinhardtii and Chlamydomonas smithii. Both mutants have a deletion in the region of the mitochondrial DNA containing the apocytochrome b gene and possibly the unidentified URFx gene.

Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy

1991 ◽  
Vol 261 (6) ◽  
pp. C1091-C1098 ◽  
Author(s):  
J. M. Kennedy ◽  
S. R. Lobacz ◽  
S. W. Kelley
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cardiac Hypertrophy ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Citrate Synthase ◽  
Incubation Temperature ◽  
Mitochondrial Gene ◽  
Gene Replication ◽  
Mitochondrial Dna Copy Number

Cardiac hypertrophy was produced in embryonic chicks by decreasing the incubation temperature from 38 degrees C to 32 degrees C on day 11. Increases in ventricular protein, RNA, and DNA support the cardiac enlargement. Cytochrome-c oxidase activity and citrate synthase activity were depressed in hypothermic ventricles by 63% and 56%, respectively. No significant differences were seen in enzyme activities in pectoralis muscles. The involvement of mitochondrial gene replication and transcription was evaluated using a cDNA clone for the mitochondrially encoded subunit III of cytochrome-c oxidase (CO III). Quantitative slot-blot analysis demonstrated that the relative CO III mRNA concentration was reduced in hypothermic ventricles. In contrast, the relative mitochondrial DNA concentration was increased in hypothermic ventricles. Taken together, these data indicate that a hypothermia-induced decrease in cytochrome-c oxidase activity is associated with a decrease in CO III mRNA, which is not coupled to a decrease in the mitochondrial DNA copy number. This dissociation of mitochondrial gene replication and transcription may provide a useful model for examining the regulation of mitochondrial biogenesis.

Senescence is coupled to induction of an oxidative phosphorylation stress response by mitochondrial DNA mutations in Neurospora

1995 ◽  
Vol 73 (S1) ◽  
pp. 198-204 ◽  
Author(s):  
Helmut Bertrand
Keyword(s):  
Mitochondrial Dna ◽  
Stress Response ◽  
Oxidative Phosphorylation ◽  
Strictly Aerobic ◽  
Wild Type ◽  
Mitochondrial Mutations ◽  
Mitochondrial Mutation ◽  
Mitochondrial Dna Mutations ◽  
Dna Mutations ◽  
Mitochondrial Dnas

In Neurospora and other genera of filamentous fungi, the occurrence of a mutation affecting one or several genes on the chromosome of a single mitochondrion can trigger the gradual displacement of wild-type mitochondrial DNA by mutant molecules in asexually propagated cultures. As this displacement progresses, the cultures senesce gradually and die if the mitochondrial mutation is lethal, or develop respiratory deficiencies if the mutation is nonlethal. Mitochondrial mutations that elicit the displacement of wild-type mitochondrial DNAs are said to be "suppressive." In the strictly aerobic fungi, suppressiveness appears to be associated exclusively with mutations that diminish cytochrome-mediated mitochondrial redox functions and, thus, curtail oxidative phosphorylation. In Neurospora, suppressiveness is connected to a regulatory system through which cells respond to chemical or genetic insults to the mitochondrial electron-transport system by increasing the number of mitochondria approximately threefold. Mutant alleles of two nuclear genes, osr-1 and osr-2, affect this stress response and abrogate the suppressiveness of mitochondrial mutations. Therefore, we propose that mitochondrial mutations are suppressive because their phenotypic effect is limited to the organelles within which the mutant DNA is located. Consequently, mitochondria that are "homozygous" for a mutant allele are functionally crippled and are induced to proliferate more rapidly than the normal mitochondria with which they coexist in a common protoplasm. While this model provides a plausible explanation for the suppressiveness of mitochondrial mutations in the strictly aerobic fungi, it may not account for the biased transmission of mutant mitochondrial DNAs in the facultatively anaerobic yeasts. Key words: mitochondria, mitochondrial DNA, mutations, suppressiveness, oxidative phosphorylation, stress response.

Decreased Cytochrome-c Oxidase Activity and Lack of Age-Related Accumulation of Mitochondrial DNA Deletions in the Brains of Schizophrenics

Genomics ◽  
1995 ◽  
Vol 29 (1) ◽  
pp. 217-224 ◽  
Author(s):  
Lucia Cavelier ◽  
Elena E. Jazin ◽  
Inger Eriksson ◽  
Jonathan Prince ◽  
Ullvi Båve ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Age Related ◽  
Dna Deletions

m.6267G>A: a recurrent mutation in the human mitochondrial DNA that reduces cytochrome c oxidase activity and is associated with tumors

2006 ◽  
Vol 27 (6) ◽  
pp. 575-582 ◽  
Author(s):  
M. Esther Gallardo ◽  
Raquel Moreno-Loshuertos ◽  
Celia López ◽  
Mercedes Casqueiro ◽  
Javier Silva ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Recurrent Mutation ◽  
Human Mitochondrial Dna
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