Effect of thyroid status on the expression of metabolic enzymes during chronic stimulation

1992 ◽  
Vol 263 (4) ◽  
pp. C788-C793 ◽  
Author(s):  
D. A. Hood ◽  
J. A. Simoneau ◽  
A. M. Kelly ◽  
D. Pette
Keyword(s):  
Enzyme Activity ◽  
Thyroid Hormone ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Tibialis Anterior ◽  
Citrate Synthase ◽  
Tibialis Anterior Muscle ◽  
Mitochondrial Genes ◽  
Thyroid Status ◽  
Chronic Stimulation

The effect of thyroid status on the expression of cytochrome c oxidase (CYTOX) and the activities of citrate synthase (CS) and phosphofructokinase (PFK) were examined in chronically stimulated (10 Hz; 35 days) and contralateral, nonstimulated rat tibialis anterior muscle of hypothyroid, hyperthyroid, and euthyroid animals. Stimulation increased CYTOX activity by 2.7-, 3.2-, and 4.9-fold in hyperthyroid, euthyroid, and hypothyroid animals, respectively, to similar absolute values. CS displayed similar increases. Stimulation reduced PFK activity in hypothyroid and euthyroid animals to 45% and 60% of control values. This effect was abolished with hyperthyroidism. Thus stimulation and thyroid hormone act antagonistically on PFK activity. Stimulation increased CYTOX subunit III (mitochondrially encoded) mRNA by 2.5- and 2.9-fold in hyperthyroid and euthyroid animals. Similar increases were observed in the nuclear-encoded mRNAs of CYTOX subunit VIc in euthyroid muscle. In hyperthyroid and euthyroid conditions, the mRNA changes paralleled the increases in enzyme activity. In hypothyroid muscle, the increase in mRNA was less for subunit VIc than III, suggesting that hypothyroidism upsets the coordinate expression of nuclear and mitochondrial genes. Further, the increases in CYTOX activity exceeded that of both subunit mRNAs in hypothyroid muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Nuclear Gene Dosage Effects Upon the Expression of Maize Mitochondrial Genes

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1711-1721
Author(s):  
Donald L Auger ◽  
Kathleen J Newton ◽  
James A Birchler
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Gene Dosage ◽  
Nuclear Gene ◽  
Eukaryotic Cell ◽  
Mitochondrial Genes ◽  
Northern Analysis ◽  
Α Subunit ◽  
Dosage Effects ◽  
A Genome

Abstract Each mitochondrion possesses a genome that encodes some of its own components. The nucleus encodes most of the mitochondrial proteins, including the polymerases and factors that regulate the expression of mitochondrial genes. Little is known about the number or location of these nuclear factors. B-A translocations were used to create dosage series for 14 different chromosome arms in maize plants with normal cytoplasm. The presence of one or more regulatory factors on a chromosome arm was indicated when variation of its dosage resulted in the alteration in the amount of a mitochondrial transcript. We used quantitative Northern analysis to assay the transcript levels of three mitochondrially encoded components of the cytochrome c oxidase complex (cox1, cox2, and cox3). Data for a nuclearly encoded component (cox5b) and for two mitochondrial genes that are unrelated to cytochrome c oxidase, ATP synthase α-subunit and 18S rRNA, were also determined. Two tissues, embryo and endosperm, were compared and most effects were found to be tissue specific. Significantly, the array of dosage effects upon mitochondrial genes was similar to what had been previously found for nuclear genes. These results support the concept that although mitochondrial genes are prokaryotic in origin, their regulation has been extensively integrated into the eukaryotic cell.

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.

Phylogeny of Dorippoidea (Crustacea : Decapoda : Brachyura) inferred from three mitochondrial genes

2009 ◽  
Vol 23 (3) ◽  
pp. 223 ◽  
Author(s):  
Y. W. Sin ◽  
Joelle C. Y. Lai ◽  
Peter K. L. Ng ◽  
K. H. Chu
Keyword(s):  
Molecular Markers ◽  
Cytochrome C ◽  
16S Rrna ◽  
Cytochrome C Oxidase ◽  
Phylogenetic Relationships ◽  
Phylogenetic Trees ◽  
Mitochondrial Genes ◽  
12S Rrna ◽  
Generic Relationships ◽  
I Gene

The phylogenetic relationships between 10 of 13 genera of crabs from the superfamily Dorippoidea were investigated using mitochondrial 16S rRNA, 12S rRNA and cytochrome c oxidase subunit I gene sequences. The resultant phylogenetic trees based on the three molecular markers support the division of Dorippidae and Ethusidae as monophyletic families within the Dorippoidea. The inferred inter-generic relationships within Dorippidae concur with groupings based on the overall morphology of the carapace and structures of the male first pleopods.

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