Use of rDNA polymorphism for identification of Heterophyidae infecting freshwater fishes

Abstract

Infections by trematodes are among the most common fish-borne zoonoses. Metacercariae of the Family Heterophyidae in marine and freshwater fishes are nonfastidious in their choice of definitive hosts, and therefore, cause infections in human and domestic animals. In the present study, species-specific polymerase chain reaction (PCR) assays were developed for identifying and differentiating the various species examined. Sequencing and aligning the 18S (SSU) rDNA revealed interspecific variation for which species-specific DNA oligonucleotides were designed and used for the identification of 6 heterophyid species recovered from piscivorous birds. The oligonucleotides were further used to evaluate the various stages (cercariae recovered from snails, metacercariae recovered from fish and adult trematodes) of the digeneans. By applying this method we elucidated for the first time the life cycle of Pygidiopsis genata. The phylogenetic interrelationship among the newly sequenced species of Heterophyidae is outlined.KEY WORDS: Digenea · Heterophyidae · Birds · Fish · 18S rDNA gene · SSU Resale or republication not permitted without written consent of the publisherDis Aquat Org 59: [35][36][37][38][39][40][41] 2004 were then used for identification of cercariae recovered from snails and metacercariae recovered from fish, demonstrating their usefulness as a diagnostic tool important for fish and public health. An effort made to define the entire life history of Pygidiopsis genata was successfully carried out. Finally we attempted to examine the phylogenetic links between the Heterophyidae and various other trematodes that were concurrently investigated. MATERIALS AND METHODSSources of parasites and morphological characterization. During 2000 to 2002, adult trematodes were collected from 45 cormorants Phalacrocorax carbo, 4 little egrets Egretta garzetta, 3 night herons Nycticorax nycticorax, 2 white pelicans Pelecanus onocrotalus and a catfish Clarias gariepinus. Collection permits were obtained from the Office of Nature Conservation, Ministry of Environmental Quality, Israel.Trematodes were collected from the sedimentation of the intestine content, then removed and placed in clean physiological saline and preserved in 70% ethanol. Several specimens of each species were fixed in 70% ethanol overnight under light pressure, stained with Aceto-Carmine, and whole mounted for morphologic examination.Metacercariae of Centrocestus sp. (gills), Haplorchis sp. (subcutaneous) Phagicola sp. (heart: conus arteriosus) and Pygidiopsis sp. (kidney), and an unidentified metacercaria from the liver, were obtained from Tilapia zillii (Cichlidae). The fish were collected from commercial fish ponds and Lake Kinneret. Clinostomum complanatum metacercariae (subcutaneous, intermuscular) were collected from Barbus canis (Cyprinidae) from Lake Kinneret. All metacercariae were preserved in 70% ethanol.Cercariae were collected from 3 species of freshwater snails (Melanoides tuberculata, Melanopsis costata and Bythinia hawaderiana) from ...

Independent host switching events by digenean parasites of cetaceans inferred from ribosomal DNA

“…Unfortunately, no sequence of P. anterouterus, the only other member of the genus Pholeter, was available to be included in the analysis. All four of these species, including P. anterouterus, are parasites from fish-eating birds (Pearson and Courtney, 1977;Sepulveda et al, 1999;Scholz and SalgadoMaldonado, 2000;Dzikowski et al, 2004;Simoes et al, 2010). Our results support the paraphyletic relationship between the Heterophyidae and the Opisthorchiidae, which had previously been suggested (Thaenkham et al, 2011(Thaenkham et al, , 2012.…”

Biomphalaria straminea (Mollusca: Planorbidae) as an intermediate host of Drepanocephalus spp. (Trematoda: Echinostomatidae) in Brazil: a morphological and molecular study

“…described here and adult Pa. radiatum from great cormorants [(Phalocrocorax carbo (Linnaeus, 1758)] in Israel. Similarly, the isolates sequenced in this study differ by more than 4.2 % at the rRNA region than Petasiger phalacrocoracis (-Yamaguti, 1939) also from P. carbo in Israel (Dzikowski et al 2004). Meanwhile, the archived D. auritus from the USA and the two Drepanocephalus spp.…”

Foodborne Intestinal Flukes in Southeast Asia

“…Sequencing and aligning of the 18S (SSU) rDNA of 6 heterophyid species, including H. taichui, H. pumilio, Centrocestus sp., Pygidiopsis genata, Phagicola longa, and Dexiogonimus ciureanus, revealed interspecific variations [304]. However, due to high sequence similarities, it was necessary to perform PCR-RFLP of the entire 18S subunit to differentiate between Haplorchis and Dexiogonimus [304]. A high annealing temperature (HAT)-based random amplified polymorphic DNA (RAPD) technique has been developed to detect DNA of H. taichui and S. falcatus [305,306].…”