title: Exceptionally high cumulative percentage of NUMTs originating from linear mitochondrial DNA molecules in the Hydra magnipapillata genome.
abstract: BACKGROUND
  In contrast to most animal genomes, mitochondrial genomes in species belonging to the phylum Cnidaria show distinct variations in genome structure, including the mtDNA structure (linear or circular) and the presence or absence of introns in protein-coding genes. Therefore, the analysis of nuclear insertions of mitochondrial sequences (NUMTs) in cnidarians allows us to compare the NUMT content in animals with different mitochondrial genome structures.
  
  
  RESULTS
  NUMT identification in the Hydra magnipapillata, Nematostella vectensis and Acropora digitifera genomes showed that the NUMT density in the H. magnipapillata genome clearly exceeds that in other two cnidarians with circular mitochondrial genomes. We found that H. magnipapillata is an exceptional ancestral metazoan with a high NUMT cumulative percentage but a large genome, and its mitochondrial genome linearisation might be responsible for the NUMT enrichment. We also detected the co-transposition of exonic and intronic fragments within NUMTs in N. vectensis and provided direct evidence that mitochondrial sequences can be transposed into the nuclear genome through DNA-mediated fragment transfer. In addition, NUMT expression analyses showed that NUMTs are co-expressed with adjacent protein-coding genes, suggesting the relevance of their biological function.
  
  
  CONCLUSIONS
  Taken together, our results provide valuable information for understanding the impact of mitochondrial genome structure on the interaction of mitochondrial molecules and nuclear genomes.
authors.affiliation: Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan 650201, China.
authors.forename: Shen
authors.initials: S
authors.lastname: Song
authors.forename: Feng
authors.initials: F
authors.lastname: Jiang
authors.forename: Jianbo
authors.initials: J
authors.lastname: Yuan
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Yongwang
authors.initials: Y
authors.lastname: Miao
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D020440:Gene Duplication / Q000235:genetics; D023281:Genomics; D006801:Humans; D006829:Hydra / Q000166:cytology / Q000235:genetics*; D059467:Transcriptome
chemical_list: D004272:DNA, Mitochondrial