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Eukaryotic cells contain extrachromosomal circular DNA (eccDNA) beyond mitochondrial and chloroplast genomes. While eccDNA is widespread and linked to genome instability, its formation, evolution, and functions remain largely unknown.

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Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • Eukaryotic DNA primarily exists as linear chromosomes, but circular DNA molecules are also present.
  • Mitochondrial and chloroplast genomes are well-studied circular DNAs.
  • Extrachromosomal circular DNA (eccDNA) of nuclear origin, including rDNA circles and microDNA, represents a broader repertoire of circular DNA in eukaryotes.

Purpose of the Study:

  • To highlight the widespread occurrence and significance of eccDNA in eukaryotic genomes.
  • To underscore the current gaps in understanding eccDNA formation, evolution, and biological functions despite growing research interest.

Main Methods:

  • Literature review and synthesis of existing research on eccDNA.
  • Analysis of studies confirming eccDNA presence across various organisms and conditions.

Main Results:

  • eccDNA has been detected in all tested organisms.
  • The presence and accumulation of certain eccDNAs vary across the cell cycle and can be induced by specific circumstances.
  • eccDNA accumulation is associated with severe genome destabilization, such as in malignancies and under stress conditions.

Conclusions:

  • eccDNA is a pervasive component of eukaryotic genomes with implications for genome stability.
  • Further research is crucial to elucidate the mechanisms behind eccDNA formation, their evolutionary trajectories, and their diverse biological roles.