The complete mitochondrial genome of the hagfish Myxine glutinosa: unique features of the control region.

The complete sequence of the mitochondrial DNA of the hagfish Myxine glutinosa has been determined. The hagfish mtDNA (18,909 bp) is the longest vertebrate mtDNA determined so far. The gene arrangement conforms to the consensus vertebrate type and differs from that of lampreys. The exceptionally long (3628-bp) control region of the hagfish contains the typical conserved elements found in other vertebrate mtDNAs but is characterized by a large number of putative hairpins, which can potentially fold into a highly compact secondary structure that appears to be unique to hagfish. The comparison of the mtDNAs of two M. glutinosa specimens, excluding the control region, shows a 0.6% divergence at the nucleotide level as a sample of intraspecies polymorphism.