Individual and population variation in cercariae of bird schistosomes of the Trichobilharzia ocellata species group as revealed with the polymerase chain reaction

Abstract

The polymerase chain reaction with arbitrary (RAPD-PCR) or specific primers was used to study the population variation and to identify the species in cercariae of schistosomes of the Trichobilharzia ocellata species group (Trematoda, Schistosomatidae). In total, 28 cercariae were obtained from two spontaneously invaded mollusks Lymnaea stagnalis (LS) and L. ovata (LO), which were collected in different ponds of Moscow. RAPD-PCR was carried out with two arbitrary primers, OPA9 and OPB11, which each detected different levels of individual and among-group variation and revealed considerable genetic differentiation of cercariae from different host mollusks. To check whether the cercariae of the two samples belong to one species, sequencing was performed with a region corresponding to intergenic transcribed spacer 2 (ITS2), which was earlier proposed for cercaria identification in three European species of bird schistosomes of the genus Trichobilharzia ( T. franki, T. regenti , and T. szidati ). The ITS2 sequences of two LO cercariae were identical, each consisted of 319 bp, and showed 100% homology to the T. franki ITS2 sequence. The ITS2 sequences of two LS cercariae were identical, each consisted of 323 bp, and showed 99.4% homology to the T. szidati counterpart. The causes of genetic variation in cercariae and prospects of using RAPD markers to study different stages of the life cycle in trematodes are discussed. MOLECULAR GENETICS

Multiple near-identical genotypes of Schistosoma japonicum can occur in snails and have implications for population-genetic analyses

“…They did not provide any further data or analysis. Semyenova et al (2005) found some evidence for generation of heterogeneity in another schistosome genus, Trichobilharzia. We know of no other explicit reports of somatic mutation in trematodes.…”

Genetic differentiation of cercariae infrapopulations of the avian schistosome Trichobilharzia szidati based on RAPD markers and mitochondrial cox1 gene

“…Previously, using two random primers, we observed cercariae RAPD variability between two Trichobilharzia species-T. szidati and T. franki (Semenova et al 2005). In addition, we demonstrated the utility of RAPD to study population genetic structure of Bucephalus polymorphus (Trematoda: Bucephalidae) using cercariae from daughter sporocysts (Korsunenko et al 2009).…”

Avian Schistosomes and Outbreaks of Cercarial Dermatitis

“…Most of the effort has been conducted using three gene regions. To date, the nuclear ribosomal DNA D1-D2 regions of 28S, the internal transcribed spacer (ITS) region, and the mitochondrial cox1 gene have been tested as molecular markers for systematics (40,63,67,69,70,105,123,248,249,251), epidemiology (252), and diagnostics (121,253). Sequencing of gene regions such as the nuclear ITS region and the mitochondrial cox1 gene not only has linked life cycle stages but also has suggested that our recognition of the diversity of avian schistosomes continues to grow (10, 12, 40, 65-67, 69, 70, 105, 129, 133, 135).…”