Characterisation of the complete mitochondrial genome of the imperiled Pearl darter Percina aurora (Perciformes: Percidae).

The Pearl darter Percina aurora, a member of the species-rich family Percidae, is endemic to the Pearl and Pascagoula river systems in Louisiana and Mississippi, USA. However, this fish is now only found in the Pascagoula River and is listed as threatened under the US Endangered Species Act. This study, for the first time, assembled and characterised in detail the mitochondrial genome of P. aurora. The mitochondrial genome of P. aurora is 16,646 bp in length and comprises 13 protein coding genes (PCGs), 22 transfer RNA genes, and 2 ribosomal RNA genes (rrnS [12s ribosomal RNA] and rrnL [16s ribosomal RNA]). A 33 bp long region was identified as the origin of replication for the light strand (OL), and a putative non-coding control region (CR), 987 bp in length, contains the origin of replication for the heavy strand (OH). The two ribosomal RNA genes, the majority of the PCGs, and the majority of the tRNA genes are encoded on the positive, or heavy, strand. The gene order in P. aurora is identical to that previously reported for confamilial species. All tRNAs exhibit a cloverleaf secondary structure except tRNA-Serine 1 which lacked the D-arm loop. An analysis of selective pressure (Ka/Ks ratios) for all the PCGs showed Ka/Ks values ≤1, suggesting that all these PCGs experience strong purifying selection. This new genomic resource will aid with bioprospecting and biomonitoring of P. aurora using environmental DNA. [ABSTRACT FROM AUTHOR]