We sequenced the complete mitochondrial DNA (mtDNA) of the articulate brachiopod @entity69927 . The circular genome is 14,291 bp in size, relatively small compared with other published metazoan mtDNAs. The 37 genes commonly found in animal mtDNA are present; the size decrease is due to the truncation of several tRNA, rRNA, and protein genes, to some @entity377 overlaps, and to a paucity of noncoding @entity2036 . Although the gene arrangement differs radically from those reported for other metazoans, some gene junctions are shared with two other articulate brachiopods, @entity69928 and @entity69929 . All genes in the @entity69927 mtDNA, unlike those in most metazoan mtDNAs reported, are encoded by the same strand. The A+T content (59.1%) is low for a metazoan mtDNA, and there is a high propensity for homopolymer runs and a strong base-compositional strand bias. The coding strand is quite G+T-rich, a skew that is shared by the confamilial (laqueid) species @entity69928 but is the opposite of that found in @entity69929 , a cancellothyridid. These compositional skews are strongly reflected in the codon usage patterns and the @entity535 compositions of the mitochondrial proteins, with markedly different usages being observed between @entity69929 and the two laqueids. This observation, plus the similarity of the laqueid noncoding regions to the reverse complement of the noncoding region of the cancellothyridid, suggests that an inversion that resulted in a reversal in the direction of first-strand replication has occurred in one of the two lineages. In addition to the presence of one noncoding region in @entity69927 that is comparable with those in the other brachiopod mtDNAs, there are two others with the potential to form secondary structures; one or both of these may be involved in the process of transcript cleavage.

The complete mitochondrial genome of the articulate brachiopod XXXX .

@entity69928 :: ('93892', 'Species') :: ['L. rubellus', 'Laqueus rubellus'] @entity2036 :: ('MESH:D009711', 'Chemical') :: ['nucleotides'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity69927 :: ('34513', 'Species') :: ['Terebratalia transversa', 'T. transversa'] @entity377 :: ('CHEBI:36976', 'Chemical') :: ['nucleotide'] @entity69929 :: ('7580', 'Species') :: ['Terebratulina retusa', 'T. retusa']
@entity69927 :: (34513,Species) :: ['Terebratalia transversa']
