Complete mitochondrial genome of the red drum, Sciaenops ocellatus (Perciformes, Sciaenidae): absence of the typical conserved motif in the origin of the light-strand replication.

In this study, the complete mitochondrial genome of the red drum Sciaenops ocellatus was determined first. The genome was 16,500 bp in length and contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and 2 main non-coding regions (the control region and the origin of the light-strand replication); the gene composition and order of which were similar to most other vertebrates. The overall base composition of the heavy strand was T 25.5%, C 30.7%, A 27.5%, and G 16.3%, with a slight AT bias of 53%. Within the control region, the discrete and conserved sequence blocks were identified. Motif 5'-ACCGG-3' rather than 5'-GCCGG-3' was detected in the origin of light-strand replication (O(L)) of red drum, which is rare in the mitogenomes of Sciaenidae species. These results would play an important role in elucidating sequence-function relationships of the O(L).