Genetic characterization of some marine catfishes in Bangladesh using DNA barcodes

Abstract

Marine catfish (Siluriformes) found in Bay of Bengal are economically important resources for Bangladesh. However, there are no studies on phylogenetic analysis of catfish species in Bangladesh at a molecular level. The species level analysis of catfish species is usually carried out through morphological characters and controversial due to phenotypic variation. In this study, the partial sequence of COI (Cytochrome Oxidase subunit I) gene was analyzed for species identification and phylogenetic relationships among 6 species of catfish sampled from Cox’s Bazar. The nucleotide sequences of COI consisted of about 750 nucleotide base pairs. The mitochondrial cytochrome oxidase I (COI) region of all samples was successfully amplified using PCR. The comprehensive barcoding identification results were based on GenBank databases. Database revealed definitive identity matches in the range of 96%-98% for consensus sequences of six species namely Osteogeneiosus militaris, Netuma thalassinus, Plicofollis tenuispinis, Plicofollis polystaphylodon, Hemiarius sona, and Nemapteryx caelata. GenBank-based identification for all species yielded an alignment E-value of 0.0. Multiple sequence alignment was done using examined sequences and downloaded sequences and phylogenetic tree was constructed where species in the present study were clustered independently within their corresponding genera. In the present study the sequence of three samples matched to Osteogeneiosus militaris in the gene bank database, but they were different in nucleotide sequence. Moreover, two samples each matched to Plicofollis tenuispinis and Plicofollis polystaphylodon with little nucleotide sequence difference. Among the 11 fish samples, morphologically identified 5 different species while using DNA barcoding of 10 samples, 6 different species were found. Moreover, among the 10 samples which where sequenced using COI gene specific primer, 3 samples showed were different identification in morphological and molecular level. This research demonstrates that partial sequences of the COI gene can efficiently identify the six species of marine catfish in Bangladesh, indicating the usefulness of COI-based approach in species identification.