Induction and characterization of mitochondrial DNA mutants in Chlamydomonas reinhardtii.

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.

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

The American Journal of Human Genetics ◽

10.1086/518901 ◽

2007 ◽

Vol 81 (1) ◽

pp. 189-195 ◽

Cited By ~ 45

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

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Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy

AJP Cell Physiology ◽

10.1152/ajpcell.1991.261.6.c1091 ◽

1991 ◽

Vol 261 (6) ◽

pp. C1091-C1098 ◽

Cited By ~ 7

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.

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