Molecular Genetics

Facts

• Mitochondrial DNAs of Xenopus laevis and X. muelleri differ enough that they do not cross hybridize at high stringency. Thus, hybridization can test the inheritance of mitochondria in interspecies crosses. When X. laevis males are crossed with X. muelleri females, less than 1% of the mitochondrial DNA of the offspring is X. laevis DNA.
• The restriction enzyme digestion patterns of donkey and horse mitochondrial DNA are different. Mules have the patterns of horses and hinnies have the patterns of donkeys. A 5% level of contamination with the other DNA source could have been detected in each case.
• In one-third of plant genera, genetic markers from both parents are found in each of the F1 and F2 progeny.
• Paternal inheritance has also been observed and is the usual pattern in conifers.
  

Interpretations

• Inheritance of mitochondrial DNA is non-Mendelian
• In vertebrates, mitochondria are usually inherited maternally.
• Biparental inheritance of non-Mendelian traits is not uncommon.

Further information

• Exclusion of the genomes of one or the other parent has diverse causes.
• Repeated back-crossing of progeny of interspecific mouse crosses to the male parent resulted in PCR-detectable paternal DNA in the offspring (ref).
• Organelles do fuse, permitting exchange of information by recombination.

This is page 1372 of Molecular Genetics by Ulrich Melcher, © 1997-8, 2003-4