New insights into the molecular phylogeny of Balantidium (Ciliophora, Vetibuliferida) based on the analysis of new sequences of species from fish hosts

Abstract

We obtained sequences of the small subunit ribosomal RNA (rRNA) for two new isolates of Balantidium from fishes, Balantidium polyvacuolum and Balantidium ctenopharingodoni. This is the first introduction of molecular data of Balantidium species from fish hosts in the phylogenetic analyses of the ciliate subclass Trichostomatia. Despite the fact that these species share morphological characteristics common to other species of Balantidium, the phylogenetic analysis of their sequences has shown that they are to be placed in a different branch closely related to the so-called Australian clade. Thus, our results indicate that the genus Balantidium is polyphyletic and possibly should be represented by two different genera; however, the analysis of more species from other poikilothermic hosts (amphibians, reptiles) should be made before a revised taxonomical proposal could be made.

Molecular genetic investigations on Balantidium ctenopharyngodoni Chen, 1955, a parasite of the grass carp (Ctenopharyngodon idella)

“…The parasite was found neither in other introduced Chinese major carp species nor in local Hungarian fishes (Molnár, 1979;Molnár, unpublished data). Recently, the 18S rRNA sequence of B. ctenopharyngodoni from China has been published (Li et al, 2014), and sequencing results obtained in our laboratory confirmed the presence of this protozoan in Hungary.…”

“…Subsequent DNA sequencing confirmed B. ctenopharyngodoni infection of the grass carp examined. The amplified and sequenced 1635-bp-long fragment of the small subunit ribosomal RNA gene (KU170970) was 99.8% similar to the partial sequence of B. ctenopharyngodoni 18S rDNA (GU480804) sequenced in China (Li et al, 2014). Another 384-bp fragment encoding the ITS1-5,8S-ITS2 region (KU170972) could also be sequenced, and this region resembled Balantidium coli (HF545448) with 86.4% identity.…”

“…The genomic region encoding the small subunit rRNA is the most frequently used genetic marker for this purpose. Molecular biological studies have concerned mostly B. coli (Nilles-Bije and Rivera, 2010;Ponce-Gordo et al, 2011;Hassell et al, 2013;Chistyakova et al, 2014;Li et al, 2014). These studies have tried to detect the genetic diversity and clarify the phylogeny of Balantidium and Balantidium-like ciliates using this genomic region.…”

“…Thus far, relatively few small subunit rRNA sequences have been determined for different Balantidium species originating from poikilothermic animals. In particular, at present only one 18S rRNA sequence represents the 19 known Balantidium species of fish origin (Li et al, 2013(Li et al, , 2014.…”

Light microscopic morphometrics, ultrastructure, and molecular phylogeny of the putative pycnotrichid Ciliate, Buxtonella sulcata

“…Their alignment was made with the program 4SALE (Seibel et al 2008) by taking into account both the primary sequence and the secondary structure; for this purpose, the secondary structure model proposed for the sequence KJ124724 of Balantidium polyvacuolum (Li et al 2014) was transferred to the other sequences by homology modeling using the "model" tool available in the ITS2 Database web site (http://its2.bioapps.biozentrum.uni-wuerzburg.de) (Koetschan et al 2010). The ambiguously aligned positions were excluded from the phylogenetic analysis.…”