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Heteroplasmy suggests limited biparental inheritance of Mytilus mitochondrial DNA

W R Hoeh1, K H Blakley, W M Brown

  • 1Laboratory for Molecular Systematics, Museum of Zoology, Ann Arbor, MI.

Science (New York, N.Y.)
|March 22, 1991
PubMed

Insights

Mussels in the Mytilus edulis species group exhibit unusual biparental mitochondrial DNA inheritance, differing from typical animal maternal inheritance. Many individuals show mixed mitochondrial DNA (heteroplasmy), challenging the norm of single mitochondrial DNA types (homoplasmy).

Area of Science:

  • Marine biology
  • Genetics
  • Mitochondrial DNA inheritance

Background:

  • Mitochondrial DNA (mtDNA) is typically maternally inherited in animals.
  • Individuals usually possess a single mtDNA population (homoplasmy).
  • Mytilus edulis species group mussels present a potential exception to these general rules.

Purpose of the Study:

  • To investigate the inheritance patterns of mitochondrial DNA in the Mytilus edulis species group.
  • To determine the prevalence of heteroplasmy and homoplasmy in Mytilus populations.
  • To test the hypothesis of biparental mtDNA inheritance in Mytilus.

Main Methods:

  • Analysis of mitochondrial DNA from 150 individuals of the Mytilus edulis species group.
  • Assessment of mitochondrial DNA types within individuals to identify heteroplasmy and homoplasmy.
  • Comparison of mitochondrial DNA sequences between different types within heteroplasmic individuals.

Main Results:

  • 85 out of 150 examined Mytilus individuals were found to be heteroplasmic for mtDNA.
  • Significant sequence divergence (20 +/- 5 percent) was observed between different mtDNA types within heteroplasmic individuals.
  • Homoplasmic individuals possessed mtDNA types similar to those found in heteroplasmic individuals.

Conclusions:

  • Mytilus mussels exhibit a high frequency of mitochondrial DNA heteroplasmy.
  • The findings strongly support the hypothesis of biparental inheritance of mitochondrial DNA in Mytilus.
  • This challenges the common understanding of strict maternal inheritance of mtDNA in the animal kingdom.

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