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Published on: September 23, 2010
Germinal proto-mitochondria from rat liver
Nikolai Vekshin1, Vladimir Kovalev1, Alina Chaplygina1
1Institute of Cell Biophysics of RAS, 142290, Pushchino, Moscow Region, Russian Federation.
Abstract:
A number of properties of the smallest (less than 0.2 μm) germinal proto-mitochondria (PRMC) from rat liver have been studied. These PRMC were obtained by filtering the light fraction of hepatic mitochondria (MC) through calibrated millipore membranes. Germinal PRMC contain in general the same proteins as MC. However, they have the reduced content of flavoproteins and zero cytochrome oxidase. Germinal PRMC, in contrast to MC, almost does not contain the "aging pigment" - lipofuscin. They have DNA; the DNA/protein ratio in them is much higher than in MC, i.e. they are poor in protein. The obtained results support the earlier assumption that MC in specialized animal cells can arise from germinal PRMC - particles smaller than 0.2 μm containing DNA. It is assumed that the DNA molecules enter to cytoplasm during degradation of old MC serves as a seed for the formation of PRMC (with the connection of nuclear DNA).
Insights
Smallest rat liver proto-mitochondria (PRMC) contain DNA and proteins similar to larger mitochondria (MC) but lack aging pigments. These findings support PRMC as precursors to MC in animal cells.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Biochemistry
Background:
- Mitochondria (MC) are vital organelles in eukaryotic cells.
- The biogenesis and origin of mitochondria are not fully understood.
- Small particles in rat liver cells, termed proto-mitochondria (PRMC), have been investigated.
Purpose of the Study:
- To characterize the biochemical and molecular properties of germinal PRMC from rat liver.
- To investigate the relationship between PRMC and mature hepatic mitochondria (MC).
- To explore the potential role of PRMC in mitochondrial biogenesis.
Main Methods:
- Isolation of PRMC from rat liver by filtering hepatic mitochondria through millipore membranes.
- Analysis of protein content, including flavoproteins and cytochrome oxidase.
- DNA content and DNA/protein ratio determination.
- Lipofuscin content assessment.
Main Results:
- PRMC ( < 0.2 μm) share proteins with MC but have reduced flavoproteins and no cytochrome oxidase.
- PRMC contain DNA with a significantly higher DNA/protein ratio than MC, indicating lower protein content.
- PRMC exhibit minimal lipofuscin, an "aging pigment" abundant in MC.
Conclusions:
- PRMC are distinct precursors to hepatic mitochondria (MC) in rat liver.
- The high DNA/protein ratio suggests PRMC are protein-poor and DNA-rich.
- PRMC may originate from DNA released during MC degradation, potentially seeding new mitochondrial formation.
