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Effect of chloramphenicol on replication of mitochondria in Tetrahymena
Abstract:
Tetrahymena pyriformis ST (3 X 10-4 cells/ml) was treated with 0.1 mg/ml chloramphenicol (CAP). Cell division ceased after 1.5 divisions with no decreased viability. Total mitochondrial volume and succinic dehydrogenase (SDH) activity/liter increased 1.7-fold and 3-fold, respectively. SDH activity/cell decreased whereas malate dehydrogenase activity/cell and respiratory control ratios and P:O ratios of isolated mitochondria were unchanged in treated cells. During 12 hours of growth in CAP the total surface area of mitochondrial inner and outer membrane was essentially unchanged or increased 4-fold, respectively. Mitochondria from cells treated with chloramphenicol had decreased size, buoyant density and protein:lipid ratio in the membranes. The membrane ubiquinone:protein ratio was unchanged. Tetrahymena cells contained 3.6 X 10-minus 12 g of mitochondrial DNA and 6,800 mitochondria in a volume of 41,000 mu-3. A 4-hour treatment with CAP caused a 4-fold increase in the number of mitochondria/cell and a 10-fold increase in mitochondria/liter in contrast to a 4-fold increase in number of mitochondria/liter in control cells. Thus CAP stimulated division of mitochondria. Individual mitochondria of treated cells had one-tenth the volume of control mitochondria. The rate of increase of mitochondrial DNA/liter was the same in control and CAP-treated cultures. The amount of DNA/mitochondrion decreased 75% in CAP-treated cells due to the rapid division of mitochondria. The cell volume, cell protein content and mitochondrial DNA content/cell decreased with growth of control cultures.
Insights
Chloramphenicol (CAP) treatment of Tetrahymena pyriformis stimulated mitochondrial division, leading to smaller mitochondria with reduced DNA per mitochondrion. This occurred without affecting cell viability or overall mitochondrial DNA synthesis rates.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Biochemistry
Background:
- Chloramphenicol (CAP) is known to inhibit protein synthesis.
- Mitochondria possess their own DNA and protein synthesis machinery.
- The effects of CAP on mitochondrial dynamics and biogenesis in Tetrahymena are not fully understood.
Purpose of the Study:
- To investigate the impact of chloramphenicol on mitochondrial biogenesis and dynamics in Tetrahymena pyriformis.
- To determine how CAP affects mitochondrial number, size, DNA content, and enzymatic activity.
Main Methods:
- Treatment of Tetrahymena pyriformis with chloramphenicol (0.1 mg/ml).
- Measurement of cell division, viability, total mitochondrial volume, and succinic dehydrogenase (SDH) activity.
- Analysis of malate dehydrogenase activity, respiratory control ratios, P:O ratios, and membrane properties (buoyant density, protein:lipid ratio).
- Quantification of mitochondrial DNA content, number of mitochondria per cell, and mitochondrial size.
Main Results:
- CAP treatment halted cell division after 1.5 divisions but maintained cell viability.
- Total mitochondrial volume and SDH activity/liter increased significantly (1.7-fold and 3-fold, respectively).
- SDH activity/cell decreased, while malate dehydrogenase activity/cell and respiratory parameters remained unchanged.
- Mitochondria became smaller, with decreased buoyant density and protein:lipid ratio, and a 4-fold increase in the number of mitochondria/cell and 10-fold increase/liter.
- Mitochondrial DNA/mitochondrion decreased by 75% due to rapid mitochondrial division, while mitochondrial DNA/liter synthesis rate was similar to controls.
Conclusions:
- Chloramphenicol stimulates mitochondrial division in Tetrahymena pyriformis.
- This leads to an increase in mitochondrial number and a decrease in individual mitochondrion size and DNA content.
- The observed changes in mitochondrial biogenesis and dynamics are a direct consequence of CAP exposure, impacting cellular energy metabolism.