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RIBOSOMAL AND MITOCHONDRIAL GENETIC MARKERS FOR MOLECULAR DIAGNOSIS OF ASCARIDIDAE, ONCHOCERCIDAE AND ANCYLOSTOMATIDAE WORMS: HOW USEFUL ARE THEY? (ID 1225)
Abstract
Introduction
Parasitic nematodes of the families Ascarididae, Ancylostomatidae, and Onchocercidae cause a great impact on human and animal populations around the globe. Molecular methods have facilitated taxa differentiation, phylogenetic analyses, and species delimitation. The aim of this study was to determine the usefulness of different molecular markers for species discrimination prospecting to identify worms not classifiable by morphometrical means.
Methods
Ribosomal (ITS-1, ITS-2, 18S) and mitochondrial (cox1,12S,16S) gene sequences of nematodes from the NCBI database were aligned and phylogenetically analyzed using Bayesian Inference algorithms. Additionally, pairwise identity matrices and violin plots were calculated.
Results
Analyses of the 18S gene in the three families demonstrated poor resolution for species-level differentiation with a minimum pairwise identity of 95.9%. The ITS-1 and ITS-2 presented the lowest inter-species similarity with 63.3% and 51.5%. Analyses of the cox1, 16S and 12S genes showed minimum inter-species similarities of 80.5%, 78.7% and 76.8%, respectively.
Conclusions
In conclusion, ribosomal genes are not recommended for the identification of a worm from these families due to their poor resolution (18S) or high variability (ITS-1, ITS-2). The use of mitochondrial markers showed better results; however, the limited number of 12S and 16S sequences in databases makes phylogenetic analysis challenging and their current use may not be practical for the identification of unknown specimens.