Germ-line Mitochondria Exhibit Suppressed Respiratory Activity to Support Their Accurate Transmission to the Next Generation

Dev Biol. 2011 Jan 15;349(2):462-9. doi: 10.1016/j.ydbio.2010.11.021. Epub 2010 Nov 26.

Abstract

Mitochondria are accurately transmitted to the next generation through a female germ cell in most animals. Mitochondria produce most ATP, accompanied by the generation of reactive oxygen species (ROS). A specialized mechanism should be necessary for inherited mitochondria to escape from impairments of mtDNA by ROS. Inherited mitochondria are named germ-line mitochondria, in contrast with somatic ones. We hypothesized that germ-line mitochondria are distinct from somatic ones. The protein profiles of germ-line and somatic mitochondria were compared, using oocytes at two different stages in Xenopus laevis. Some subunits of ATP synthase were at a low level in germ-line mitochondria, which was confirmed immunologically. Ultrastructural histochemistry using 3,3'-diaminobenzidine (DAB) showed that cytochrome c oxidase (COX) activity of germ-line mitochondria was also at a low level. Mitochondria in one oocyte were segregated into germ-line mitochondria and somatic mitochondria, during growth from stage I to VI oocytes. Respiratory activity represented by ATP synthase expression and COX activity was shown to be low during most of the long gametogenetic period. We propose that germ-line mitochondria that exhibit suppressed respiration alleviate production of ROS and enable transmission of accurate mtDNA from generation to generation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3,3'-Diaminobenzidine
  • Animals
  • Blotting, Western
  • Cell Respiration / physiology
  • Electron Transport Complex IV / metabolism
  • Female
  • Gene Expression Profiling
  • Germ Cells / cytology*
  • Microscopy, Electron
  • Mitochondria / physiology*
  • Mitochondria / ultrastructure
  • Mitochondrial Proton-Translocating ATPases / metabolism
  • Oocytes / metabolism
  • Reactive Oxygen Species / metabolism*
  • Xenopus laevis / embryology*
  • Xenopus laevis / metabolism

Substances

  • Reactive Oxygen Species
  • 3,3'-Diaminobenzidine
  • Electron Transport Complex IV
  • Mitochondrial Proton-Translocating ATPases