The complete mitochondrial genome of the clam Mactra veneriformis (Bivalvia: Mactridae): Has a unique non-coding region, missing atp8 and typical tRNA Ser.

Mactra veneriformis (Bivalvia: Mactridae) is one commonly cultured bivalve species in the western Pacific Ocean. In the current study, the complete mitrochondrial DNA (mtDNA) of the clam M. veneriformis was determined. The M. veneriformis mt genome is 16,854 bp in length and encodes 34 genes on the same strand, including 12 protein-coding genes (PCGs), 2 ribosomal RNA genes and 20 transfer RNA genes. The length of 12 PCGs is 11,358 bp, which accounts for 67.4% in whole mt genome. The proportion is similar to other clams' mt genomes and within those of bivalves mt genomes. Gene order (which is the same as that of RZ C. antiquata) of M. veneriformis mt genome is compared with that of other veneroids. Compared with the typical gene content of animal mt genomes, atp8 and two tRNA Ser genes are missing in the mt genome. All non-coding regions are 1978 bp in length, among them the longest one is speculated as the control region, which is located between the tRNA His and tRNA Arg. The secondary largest non-coding region (NCR664) between the tRNA Gln and tRNA Thr in the M. veneriformis mt genome contains one section of tandem repeats (125 nt × 5.2 or 249 nt ×  2.6). The tandem repeats account for 97.89% (650/664) of the NCR664, which is a unique characteristic of the M. veneriformis mt non-coding regions compared with those of other veneroids. [ABSTRACT FROM AUTHOR]