Heteroplasmy, Length, and Sequence Characterization of the Mitochondrial Control Region in Tomistoma schlegelii

This study describes the organization of the repetitive pattern in the mtDNA control region of Tomistoma schlegelii. Using newly designed primers, we detected length variations of approximately 50–100 bp among individuals, and only one individual showed a heteroplasmic band. Sequencing the region after CSB III revealed two main patterns: a repeat motif and a variable number tandem repeat (VNTR) pattern. The VNTR region, with a core unit of 104 bp, consisting of four motifs and a short AT chain, is implicated in the length variation seen among individuals of Tomistoma. A conserved motif seen in a family unit indicated that the repeat pattern was stably inherited from the maternal parent to all offspring. A combination of VNTR patterns specific to different crocodilians was seen in Tomistoma, and the overall secondary structure was shown to be similar to that in Crocodylus and Gavialis.