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Abstract:
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The etiological agent of fibropapillomatosis (FP), a neoplastic disease originally identified only on green sea turtles (Chelonia mydas), is still unknown. The involvement of an environmental cofactor appears possible since many FP outbreaks occur at sites of poor water quality in Florida, Hawaii, Brazil, and other similar places around the world. Studies have shown an association between FP and the fibropapilloma- associated turtle herpesvirus (FPTHV), but not all turtles with FPTHV develop FP. Recently, high viral loads of FPTHV were detected in marine turtle leeches (Ozobranchus spp.) from a green sea turtle. However, the study failed to identify the species of marine leech. Leeches may transmit or activate FPTHV but are impossible to identify at all life stages using standard taxonomic practices. In this study, character- based DNA barcoding using mitochondrial cytochrome c oxidase I (COI) gene as a molecular marker was employed to identify both species of Ozobranchus spp. (Ozobranchus branchiatus and Ozobranchus margoi) at all stages of development from different sites in Florida and Hawaii. In addition, phylogenetic analysis of O. branchiatus at other genes (18S rDNA, 28S rDNA, and histone H3) is being used to establish whether specimens from Hawaii and Florida are distinct species. Genetic sequences for O. branchiatus and O. margoi were submitted to the National Center for Biotechnology Information GenBank. This is the first study to submit genetic data for O. branchiatus. The spread of FP to other species of turtles combined with the discovery of a new turtle host for the O. branchiatus leech suggests the vector organism involvement behind FP may be species specific. However, an extensive molecular data set must be assembled in order to confirm whether the separate haplotypes identified for O. branchiatus on a loggerhead are indeed haplotypes of the same species and not the discovery of cryptic specimens. |
