Author(s): Megbowon I and Fashina-Bombata HA

Abstract: The knowledge of molecular biology and biotechnology has contributed significantly to genetics in fisheries and aquaculture across the world, particularly in taxonomy. This study was conducted to explore molecular biology, using DNA technology to characterize the unidentified cichlid ‘Wesafu’ which will serve as a prelude naming the fish. Total genomic DNA was extracted from 10 specimens for ‘Wesafu’, Tilapia guineensis, Sarotherodon melanotheron and Tilapia mariae using the standard protocol. Amplification reactions were performed on Gene Amp® PCR System (Applied Biosystems Inc.) in a total volume of 25 ml containing 25 ng of extracted genomic DNA template, 10 mM of Tris-HCl (pH 9.0), 50 mMKCl, 1.5 mM MgCl₂, 0.01% gelatin, 200 mM each of dATP, dTTP, dCTP and dGTP, 1 unit of Taq DNA polymerase and 12-15 pM each of forward and reverse primers. PCR products were purified using the KT 62 Gene quick PCR purification kit and bidirectional cycle sequencing was performed on ABI 3100 PE automated capillary sequencer. Phylogenetic analysis based on Neighbour Joining consensus produced three distinct clusters, one containing X1, X2, X4 (Tilapia guineensis), Y3, Z1 and Z2, the second cluster containing ‘Wesafu’, W1, W2, W3, W4 and W5, and the third cluster containing T. mariae, V1 and V4. As for the data base search of the first cluster, it showed a positive alignment with T. rendalli but from unvalidated database, with 91% confidence. The results of molecular analysis using ND2 segment revealed higher degree of similarity between ‘Wesafu’ and Sarotherodon galileaus, Oreochromis niloticus, Oreochromis aureus Stomatepia mariae, Sarotherodon caroli and Stomatepia mongo. When the nucleotide sequences were translated to protein sequences, it was observed that the sequence of ‘Wesafu’ was similar to Sarotherodon galilaeus than any other cichlids in the data base. This suggest that this cichlid ‘Wesafu’ is a strain of Sarotherodon galileaus.

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