Conservation of Intronic Sequences in Vertebrate Mitochondrial Solute Carrier Genes (Zebrafish, Chicken, Mouse and Human)

The conservation of intronic sequences was studied in the mitochondrial solute carrier (SLC25A*) genes of Zebrafish, Chicken, Mouse and Human. These genes are homologous and the coding sequences have been well conserved throughout Vertebrates, but the corresponding intronic sequences have been extensively re-edited. However, significant segments of Zebrafish introns are conserved in Chicken, Mouse and Human in carriers SLC25A3, SLC25A21, SLC25A25, SLC25A26, and SLC25A36; Chicken intron segments are conserved in Mouse or Human in three additional carriers, namely SLC25A12, SLC25A13, and SLC25A29. Thus, a quota of the intronic sequences of Euteleostomi has been transferred (through Sarcopterygii) to Birds and (through Sarcopterygii and ancestral Mammals) to Mouse and Human. The degree of conservation of Euteleostomi-derived sequences is low and quite similar in Chicken, Mouse and Human (0.23⁻0.27%). The overall degree of conservation of Sarcopterygii-derived sequences in Mammals is higher, and it is significantly higher in Human than in Mouse (4.4% and 3.2%, respectively). Some of the conserved intronic sequences of SLC25A3, SLC25A21, SLC25A25, and SLC25A29 are exonized in some transcript variants of Zebrafish, Chicken, Mouse, and Human and, with minor nucleotide changes, in other Birds or Mammals.