Characterization of the complete mitochondrial genome of the red crayfish, Procambarus clarkii (Decapoda: Cambaridae).

Here we present the complete mitochondrial (mt) genome of Procambarus clarkii (Decapoda: Cambaridae) and provide its annotation. The complete mt genome was determined to be 15 929 bp and contains 22 tRNA genes, 13 protein-coding genes (PCGs), two rRNA genes, and a D-loop region. The nucleotide composition was biased toward A + T nucleotides (72.91%) and the AT skew of this mt genome was slightly negative. All the 22 tRNA genes displayed a typical clover-leaf structure, with the exception of trnS1 (AGN). About 13 PCGs were initiated by ATN codons, except for cox1 and nad2 genes which were initiated by ACG and GTG, respectively. Six of the 13 PCGs harbor the incomplete termination codon by T or TA. The D-loop region of the mt genome was 1188 bp in length and the A + T content was 81.08%. Phylogenetic analysis showed that the placement of P. clarkii was within the Cambaridae. This mt genome sequence will provide a better understanding for crayfish evolution in the future.

Identification of the complete mitochondrial genome of the pacific white shrimp Litopenaeus vannamei (Decapoda: Penaeidae).

The complete mitochondrial genome (mitogenome) of Litopenaeus vannamei was determined to be 15 989 bp in size, it contains 22 tRNA genes, 13 protein-coding genes (PCGs), two rRNA genes and a D-loop region. The nucleotide composition was biased toward A + T nucleotides (67.8%) and the AT skew of this mitogenome was slightly negative (-0.025). All tRNA genes displayed a typical clover-leaf structure, except for trnS1 (AGN). Thirteen PCGs were initiated by ATN codons, except for cox1 gene which was initiated by ACG. Four of the 13 PCGs had the incomplete termination codon by T. The rrnL was 1371 bp and the rrnS was 853 bp, and the AT content of the combined rRNA genes was 70.9%. The D-loop region of the mitogenome was 985 bp in length and the A + T content was 82.7%, and no tandem repeat was found in this region. Phylogenetic analysis showed that the placement of L. vannamei was within the Penaeidae.

The complete mitochondrial genome of the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae).

The complete mitochondrial genome (mitogenome) of Tribolium castaneum (Coleoptera: Tenebrionidae) was determined to be 15,883 bp (GenBank accession No. KM009121), which contains 22 tRNA genes, 13 protein-coding genes (PCGs), 2 rRNA genes and a major non-coding A + T-rich region. It has the typical gene organization and order of mitogenomes from ancestral insects. The nucleotide composition was also biased toward A + T nucleotides (71.72%) and the AT skew of this mitogenome was slightly positive. All of the 22 tRNA genes displayed a typical clover-leaf structure, with the exception of trnS1 (AGN). Thirteen PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which was initiated by AAT. Eight of the 13 PCGs harbor the incomplete termination codon by T or TA. The A + T-rich region of the mitogenome was 1237 bp in length and the A + T content was 82.30%.