The Folmer COI mtDNA universal primers that are considered standard for DNA barcoding of life contain so many mismatches against the target sequences of vertebrate origin that they often end in failure to amplify many of vertebrate DNA extractions. This discrepancy favors for the selection and designing of new metabarcode primers that can be used to identify all individuals of vertebrates or at least all individuals represented in a class of Vertebrata such as Class Pisces. The current study embarks on such an endeavor. In this study development of new mtDNA metabarcode (16SrRNA) that can be used as universal primers to amplify almost all species of Class Aves for different forensic and molecular biodiversity analyses.
Fins/tissue samples were collected from Class Pisces (one specimen from every order reported to be present in Pakistan). DNA was extracted from the collected specimens through standard organic method, qualified and quantified and then PCR-amplified using novel universal primers selected from aligned mtDNA sequences originating from all Pisces mitochondrial DNA genomes submitted to different online sequence databases such as NCBI nucleotide database. The sensitivity of PCR also be assessed using a range of DNA concentrations. The amplified products were sequenced on ABI Genetic Analyzer following Sanger’s dideoxy method of sequencing. The correctness of obtained mtDNA sequences were examined visually in Chromas Lite 2.1 software and then alignment of these sequences were performed against highly similar DNA sequences in NCBI nucleotide databases using BLAST in order to identify origin of unknown mtDNA sequences. With the help of sequencing and phylogenetic studies specificity of the universal primer set confirmed and presented as a novel metabarcode (16SrRNA) for species level identification of large number of Piscean species
In summary, we present universal method for species classification of Pisces using a targeted parallel sequencing approach. Both sequencing and phylogenetic studies experiments confirm specificity of universal primer set. Although promising results were obtained with current settings, rapid improvement of bench top instruments will further develop method with less hands-on, fewer sequencing errors and lower detection limit. So, in future, this barcode can be used for species identification in various fields of study such as meat adulteration, illegal trade, food mislabeling and molecular estimation of biodiversity.