Nuclear mutations affecting mitochondrial structure and function in Chlamydomonas.

Wild type cells of the green alga Chlamydomonas reinhardtii can grow in the in the dark by taking up and respiring exogenously supplied acetate. Obligate photoautotrophic (dark dier, dk) mutants of this alga have been selected which grow at near wild type rates in the light, but rapidly die when transferred to darkness because of defects in mitochondrial structure and function. In crosses of the dk mutants to wild type, the majority of the mutants are inherited in a mendelian fashion, although two have been isolated which are inherited in a clearly nonmendelian fashion. Nine mendelian dk mutants have been analyzed in detail, and belong to eight different complementation groups representing eight gene loci. These mutants have been tentatively grouped into three classes on the basis of the pleiotropic nature of their phenotypic defects. Mutants in Class I have gross alterations in the ultrastructure of their mitochondrial inner membranes together with deficiencies in cytochrome oxidase and antimycin/rotenone-sensitive NADH-cytochrome c reductase activities. Mutants in Class II have a variety of less severe alterations in mitochondrial ultrastructure and deficiencies in cytochrome oxidase activity. Mutants in Class III have normal or near normal mitochondrial ultrastructure and reduced cytochrome oxidase activity. Eight of the nine mutants show corresponding reductions in cyanide-sensitive respiration.

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Effects of Chloramphenicol on the Mitochondrial Respiratory Chain in the Wild Strain and in a Cytoplasmic Chloramphenicol-Resistant Mutant ofTetrahymena pyriformis

Molecular and Cellular Biology ◽

10.1128/mcb.2.6.715 ◽

1982 ◽

Vol 2 (6) ◽

pp. 715-719 ◽

Cited By ~ 1

Author(s):

Roland Perasso ◽

Jean-Jacques Curgy ◽

Nicole Stelly ◽

Jean Andre

Keyword(s):

Oxygen Consumption ◽

Cytochrome Oxidase ◽

Oxidase Activity ◽

Wild Strain ◽

Resistant Mutant ◽

Wild Type ◽

Mitochondrial Translation ◽

Cytochrome Oxidase Activity ◽

In The Wild ◽

Mitochondrial Respiratory

The effects of chloramphenicol (CAP) on mitochondrial respiratory activity in the wild strain (ST) and in a cytoplasmic CAP-resistant mutant (STR1) ofTetrahymena pyriformiswere studied by determining oxygen consumption, by spectrophotometry, and by cytochemistry. In the absence of CAP both strains had the same respiration capacity, and the low-temperature spectra of their isolated mitochondria were similar. Furthermore, the mitochondria of both strains showed a positive reaction with diaminobenzidine, denoting a similar cytochrome oxidase activity. However, when cells were grown in CAP for 24 or 48 h, the peaks of cytochrome oxidase and cytochromebwere almost absent in the wild type. In this type the oxygen consumption was greatly decreased, and the mitochondria were no longer stained by diaminobenzidine. In the mutant, the peaks of cytochrome oxidase and cytochromebwere decreased only; respiration was less affected than in the wild type, and cytochrome oxidase activity was still disclosed by the diaminobenzidine reaction. These results show that CAP inhibits the synthesis of two cytochromes (band oxidase) which are partially translated into the mitochrondria ofT. pyriformis.In the mutant, CAP reduces only the mitochondrial translation, resulting in reduced mitochondrial activity and reduced growth rate of the cell. These results are compared with the nucleo-mitochondrial regulation mechanisms discussed in our previous works.

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Effect of Anaerobiosis on Respiratory Rate, Cytochrome Oxidase Activity and Mitochondrial Structures in Coleoptiles of Rice (Oryza Sativa L.)

Journal of Cell Science ◽

10.1242/jcs.12.3.725 ◽

1973 ◽

Vol 12 (3) ◽

pp. 725-739

Author(s):

HELGI ÖPIK

Keyword(s):

Oryza Sativa ◽

Cytochrome Oxidase ◽

Oxidase Activity ◽

Oryza Sativa L ◽

Leaf Growth ◽

Normal Structure ◽

Cell Number ◽

Cytochrome Oxidase Activity ◽

Mitochondrial Structure ◽

Rice Coleoptile

An attempt has been made to correlate respiration rate, cytochrome oxidase activity and mitochondrial structure in coleoptiles of rice, Oryza sativa L., germinated under aerobic and anaerobic conditions. The rice coleoptiles emerge from the grain and elongate considerably even under complete anaerobiosis, which totally suppresses root and leaf growth. Cell number, dry weight and nitrogen content per coleoptile are all lowered, although some cell division and translocation of reserves into the coleoptile does take place under anaerobiosis. Compared with coleoptiles from air-grown seedlings, anaerobically grown coleoptiles have a much lower capacity for respiratory oxygen uptake and their cytochrome oxidase activity is depressed even more. Mitochondria, however, are still abundant in 4-day-old anaerobic coleoptiles, with a crista density only slightly lower than in cells of aerobically grown coleoptiles. Since, in the embryonic coleoptile of the ungerminated grain, mitochondria show very little internal structure, a considerable amount of elaboration of mitochondrial structure must occur in the rice coleoptile under anaerobiosis, contrasting with the situation in yeast, where mitochondria of normal structure are formed only in aerobic conditions. Since a high crista density develops in rice coleoptile mitochondria with a very much depressed cytochrome oxidase activity, there is no obligate correlation between crista density and cytochrome oxidase activity in this tissue.

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Myc Stimulates Nuclearly Encoded Mitochondrial Genes and Mitochondrial Biogenesis

Molecular and Cellular Biology ◽

10.1128/mcb.25.14.6225-6234.2005 ◽

2005 ◽

Vol 25 (14) ◽

pp. 6225-6234 ◽

Cited By ~ 346

Author(s):

Feng Li ◽

Yunyue Wang ◽

Karen I. Zeller ◽

James J. Potter ◽

Diane R. Wonsey ◽

...

Keyword(s):

Mitochondrial Biogenesis ◽

Structure And Function ◽

Wild Type ◽

Primary Hepatocytes ◽

Mitochondrial Mass ◽

Mitochondrial Structure ◽

Direct Binding ◽

Rat Fibroblasts ◽

And Function

ABSTRACT Although several genes involved in mitochondrial function are direct Myc targets, the role of Myc in mitochondrial biogenesis has not been directly established. We determined the effects of ectopic Myc expression or the loss of Myc on mitochondrial biogenesis. Induction of Myc in P493-6 cells resulted in increased oxygen consumption and mitochondrial mass and function. Conversely, compared to wild-type Myc fibroblasts, Myc null rat fibroblasts have diminished mitochondrial mass and decreased number of normal mitochondria. Reconstitution of Myc expression in Myc null fibroblasts partially restored mitochondrial mass and function and normal-appearing mitochondria. Concordantly, we also observed in primary hepatocytes that acute deletion of floxed murine Myc by Cre recombinase resulted in diminished mitochondrial mass in primary hepatocytes. Our microarray analysis of genes responsive to Myc in human P493-6 B lymphocytes supports a role for Myc in mitochondrial biogenesis, since genes involved in mitochondrial structure and function are overrepresented among the Myc-induced genes. In addition to the known direct binding of Myc to many genes involved in mitochondrial structure and function, we found that Myc binds the TFAM gene, which encodes a key transcriptional regulator and mitochondrial DNA replication factor, both in P493-6 lymphocytes with high ectopic MYC expression and in serum-stimulated primary human 2091 fibroblasts with induced endogenous MYC. These observations support a pivotal role for Myc in regulating mitochondrial biogenesis.

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Aluminum Impairs Rat Neural Cell Mitochondria In Vitro

International Journal of Immunopathology and Pharmacology ◽

10.1177/039463200501800410 ◽

2005 ◽

Vol 18 (4) ◽

pp. 683-689 ◽

Cited By ~ 26

Author(s):

P.Y. Niu ◽

Q. Niu ◽

Q.L. Zhang ◽

L.P. Wang ◽

S.C. He ◽

...

Keyword(s):

Mitochondrial Membrane ◽

Cell Function ◽

Structure And Function ◽

Neural Cells ◽

Oxygen Species ◽

Mitochondrial Ultrastructure ◽

Cell Death Rate ◽

Mitochondrial Structure ◽

And Function

Exposure to aluminum has been reported to lead to neurotoxicity. Mitochondria are important organelles involved in maintaining cell function. This study investigates the effect of aluminum on mitochondria in rat neural cells. The ultrastructure of mitochondria was observed, and the cell death rate (CDR), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and 3-[4,5demethyl-2-thiazalyl]-2,-5diphenyl-2H-tetrazolium bromide (MTT) were measured to investigate the effect of aluminum on the mitochondrial structure and its function in neural cells. Results observed from the mitochondrial ultrastructure show that aluminum may impair the mitochondrial membrane and cristae. Increased CDR, enhanced ROS, decreased MMP, and decreased enzyme activity in mitochondria were observed in the Al-exposed neurons (100 – 500 μM). The present study demonstrates that alteration in the mitochondrial structure and function plays an important role in neurotoxic mechanisms induced by aluminum.

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32. Correlation in cryoinjury of mitochondrial ultrastructure with respiratory control ratio, cytochrome oxidase activity, and rate of tissue oxygen consumption

Cryobiology ◽

10.1016/s0011-2240(70)80045-1 ◽

1970 ◽

Vol 6 (6) ◽

pp. 581

Keyword(s):

Oxygen Consumption ◽

Cytochrome Oxidase ◽

Oxidase Activity ◽

Respiratory Control ◽

Respiratory Control Ratio ◽

Mitochondrial Ultrastructure ◽

Tissue Oxygen ◽

Cytochrome Oxidase Activity ◽

Tissue Oxygen Consumption

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Effects of Chloramphenicol on the Mitochondrial Respiratory Chain in the Wild Strain and in a Cytoplasmic Chloramphenicol-Resistant Mutant of Tetrahymena pyriformis

Molecular and Cellular Biology ◽

10.1128/mcb.2.6.715-719.1982 ◽

1982 ◽

Vol 2 (6) ◽

pp. 715-719

Author(s):

Roland Perasso ◽

Jean-Jacques Curgy ◽

Nicole Stelly ◽

Jean Andre

Keyword(s):

Oxygen Consumption ◽

Cytochrome Oxidase ◽

Oxidase Activity ◽

Wild Strain ◽

Resistant Mutant ◽

Tetrahymena Pyriformis ◽

Wild Type ◽

Cytochrome Oxidase Activity ◽

In The Wild ◽

Mitochondrial Respiratory

The effects of chloramphenicol (CAP) on mitochondrial respiratory activity in the wild strain (ST) and in a cytoplasmic CAP-resistant mutant (STR 1 ) of Tetrahymena pyriformis were studied by determining oxygen consumption, by spectrophotometry, and by cytochemistry. In the absence of CAP both strains had the same respiration capacity, and the low-temperature spectra of their isolated mitochondria were similar. Furthermore, the mitochondria of both strains showed a positive reaction with diaminobenzidine, denoting a similar cytochrome oxidase activity. However, when cells were grown in CAP for 24 or 48 h, the peaks of cytochrome oxidase and cytochrome b were almost absent in the wild type. In this type the oxygen consumption was greatly decreased, and the mitochondria were no longer stained by diaminobenzidine. In the mutant, the peaks of cytochrome oxidase and cytochrome b were decreased only; respiration was less affected than in the wild type, and cytochrome oxidase activity was still disclosed by the diaminobenzidine reaction. These results show that CAP inhibits the synthesis of two cytochromes ( b and oxidase) which are partially translated into the mitochrondria of T. pyriformis. In the mutant, CAP reduces only the mitochondrial translation, resulting in reduced mitochondrial activity and reduced growth rate of the cell. These results are compared with the nucleo-mitochondrial regulation mechanisms discussed in our previous works.

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