![]() ![]() ![]() The severe forms developed only in “early” stages under all doses of cercariae exposure. robusta induced anomaly P in 82% of surviving tadpoles. The exposure of tadpoles to the cercariae of S. Differences in the survival rates were observed between the exposed and unexposed tadpoles both in the group of “early” tadpoles and “late” tadpoles. ResultsĪ total of 58 (72.5%) tadpoles survived until metamorphosis under the dose-dependent experiment with the trematode S. The tadpoles were exposed to parasites at four doses of cercariae (control, low, medium and high) and divided into two groups: “early” (at 25–27 Gosner stages) and “late” (at 29–34 Gosner stages) exposure. Identification of cercariae species was made using morphological and molecular methods (sequencing of ITS2 and 28S rRNA). robusta were tested for the possibility to cause anomalies. To verify teratogenic features of the species, cercariae of S. Metacercariae from tadpoles with anomaly P were identified using ITS2 gene sequencing as Strigea robusta (Trematoda: Strigeidae). We thus proposed the ‘trematode hypothesis’, according to which the infectious agent responsible for anomaly P is a trematode species. ![]() In a previous study, we obtained anomaly P in the laboratory in tadpoles of water frogs that developed together with molluscs Planorbarius corneus (Mollusca: Gastropoda) collected in the field. The cause of this anomaly remains unknown for 70 years. At the end of the 1940s, the French biologist Jean Rostand discovered a polymorphic syndrome in some water frog (Anura: Pelophylax) populations that included polydactyly and some severe morphological anomalies (he called it ‘anomaly P’). Cases of polydactyly in natural populations of amphibians have attracted great interest from biologists. ![]()
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