Morphological and molecular characterization of the ciliate parasite Tetrahymena rostrata infecting the renal organ of the dusky slug (Arion fuscus)

Abstract

The histophagous ciliate Tetrahymena rostrata (Kahl, 1926) is a facultative parasite of the renal organ of land snails and slugs. The possibility of transovum transmission and the lack of hetero-parental sex make T. rostrata an interesting model for studying host specificity and distribution patterns in pathogenic ciliates. We recorded mass Tetrahymena infection in the dusky slug (Arion fuscus (O.F. Müller, 1774)) collected in Slovakia, Central Europe. Based on the mitochondrial 16S rRNA gene and barcoding COI sequences, Slovak isolates belong to the TRO-1 subgroup. Strains of T. rostrata, however, do not cluster according to the relatedness of their gastropod hosts, i.e., various phylogenetically unrelated snails and slugs are parasitized by members of both T. rostrata subclades (TRO-1 and TRAUS). Invasion of adult gastropods through the integumentary pouch might be thus a more important transmission way than the transovum route. Geographic distances of T. rostrata isolates are not correlated with divergences in COI sequences. The absence of a clear relationship between genetic and geographic distances might have been, however, also caused by the human-mediated transmission of invasive gastropods.

2D approach to reconstruct the evolutionary history of clevelandellids (Ciliophora, Armophorea) inhabiting the hindgut of the Panesthiinae cockroaches

“…More specifically, the V9 region has gradually shortened from N. nakhoni (166 nt) and N. galerus (132 nt), the sister group of all other species included in the present analyses, through N. angustipennis (115 nt) and N. ovalis (118 nt), the sister group of the family Clevelandellidae, to the family Clevelandellidae, whose members share the shortest helix 44 (103–105 nt) (Figure 8). A relatively long hypervariable region V9 was also found in the ciliate genera Haptophrya (145–148 nt), Hysterocineta (124 nt), Tetrahymena (166–169 nt), and Trichodina (122–123 nt) (Obert et al, 2023; Rataj et al, 2022; Zhang et al, 2023; Zhang & Vďačný, 2023). Remarkable structural features of the 16S rRNA molecule in ciliates include the absence/reduction of helices 26 and 26a in Trichodina (Zhang et al, 2023) as well as an extraordinarily long and branched helix 40 in Haptophrya (Rataj et al, 2022).…”

Findings on three endocommensal scuticociliates (Protista, Ciliophora) from freshwater mollusks, including their morphology and molecular phylogeny with descriptions of two new species

“…While the majority of ciliates are free-living in aquatic and terrestrial habitats (de Puytorac et al 1994 ; Hu et al 2019 ; Song et al 2009 ; Wang et al 2022 ), a substantial portion, encompassing at least 2600 species, are symbionts (Corliss 2000 ). Symbiotic ciliates are present in a broad spectrum of invertebrate and vertebrate hosts, including mollusks, which are one of the most broadly distributed and diverse invertebrate groups (Irwin and Lynn 2015 ; Lu et al 2023 ; Lynn et al 2018 ; Mayén-Estrada et al 2021 ; Prosser et al 2018 ; Raabe 1967 , 1970 , 1971 , 1972 ; Song et al 2003 ; Souidenne et al 2019 ; Van As and Basson 2004 ; Zhang and Vďačný 2021 , 2022 , 2023a , b , 2024 ).…”

Protecting Complex Biodiversity Systems: Ciliophora Endosymbionts of the Threatened Freshwater Mussel Species Unio crassus

“…to molluscs, as a ciliate parasite Tetrahymena rostrata infecting the renal organ of the dusky slug (Arion fuscus)[39], and T. foissneri sp. n. hosted by invasive Lusitanian slug (Arion vulgaris) and T. unionis sp.…”