The structure of the Australian and South American marsupial mitochondrial control region.
The mitochondrial control region (CR) was studied across five marsupialian orders, in order to give a detailed overview of its features. The CR is organised into three domains similar to the CR of placental mammals. However, the conservation of different features among the marsupial orders is in general more strict. In the first domain, two conserved blocks extended termination-associated sequences (ETAS 1 and ETAS 2) are present in all marsupial orders. In the third domain, the three conserved sequence blocks (CSB 1, CSB 2 and CSB 3) are present and complete, with CSB 1 being duplicated in four of five marsupial orders. The nucleotide frequency and secondary structures of the repeats were typical for marsupial species. The repeats are generally AT-rich except in Dasyuridae and Paucituberculata, which show a significant increase in GC content.