New primers reveal the presence of a duplicate histone H3 in the marine turtle leech Ozobranchus branchiatus

Marine leeches, specific to sea turtles, have been implicated as potential vector organisms in the spread of fibropapillomatosis (FP), a pandemic neoplastic disease with Chelonia mydas having the highest affliction rate. Polymerase chain reaction identified two independent, seemingly functional histone H3 loci for marine turtle leeches Ozobranchus branchiatus collected from C. mydas in Florida and Hawaii. Primers were developed to amplify each product separately. Among the two loci, sequence differentiation ( Φ ST ) ranged from 0.161 to 0.182 with identical amino acid translations among the 22 samples. A maximum parsimony tree of GenBank histone H3 sequences from annelids indicated the gene duplication occurred within the Ozobranchidae family. Geographically separated populations yielded Φ ST values of 0.004–0.005 but were phylogenetically distinctive. These novel markers will be useful in identifying ectoparasites in FP research, evaluating other histone variants, and chromatin dynamics regulation studies.