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Conjugation in the spirotrich ciliate Halteria grandinella (Muller, 1773) Dujardin, 1841 (Protozoa, Ciliophora) and its phylogenetic implications.

ABSTRACT: The conjugation of Halteria grandinella was studied in protargol preparations. The isogamontic conjugants fuse partially with their ventral sides to a homopolar pair. The first maturation division generates dramatic transformations: (i) the partners obtain an interlocking arrangement; (ii) the number of bristle kineties decreases from seven to four in each partner; and (iii) the right conjugant loses its buccal membranelles, the left the whole adoral zone. The remaining collar membranelles arrange around the pair's anterior end and are shared by both partners; finally, the couple resembles a vegetative specimen in size and outline. The vegetative macronucleus fragments before pycnosis. The micronucleus performs three maturation divisions, but only one derivative each performs the second and third division. The synkaryon divides twice, producing a micronucleus, a macronucleus anlage, and two disintegrating derivatives. Scattered somatic kinetids occur during conjugation, but disappear without reorganization. An incomplete oral primordium originates in both partners. The conjugation of Halteria grandinella resembles in several respects that of hypotrich spirotrichs; however, the majority of morphological, ontogenetical, and ultrastructural features still indicates an affiliation with the oligotrich and choreotrich spirotrichs. Accordingly, the cladistic analysis still contradicts the genealogy based on the sequences of the small subunit rRNA gene.

SUBMITTER: Agatha S

PROVIDER: S-EPMC2847824 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Conjugation in the spirotrich ciliate Halteria grandinella (Müller, 1773) Dujardin, 1841 (Protozoa, Ciliophora) and its phylogenetic implications.

Agatha Sabine S Foissner Wilhelm W

European journal of protistology 20081016 1

The conjugation of Halteria grandinella was studied in protargol preparations. The isogamontic conjugants fuse partially with their ventral sides to a homopolar pair. The first maturation division generates dramatic transformations: (i) the partners obtain an interlocking arrangement; (ii) the number of bristle kineties decreases from seven to four in each partner; and (iii) the right conjugant loses its buccal membranelles, the left the whole adoral zone. The remaining collar membranelles arran ...[more]

PMID: 18929469

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Project description:Simple Summary Rare organisms represent a challenge for researchers in all fields of study in biology. In the realm of ciliatology, the genera Dactylochlamys and Legendrea are considered to be such cases. Very little information has accrued in over a century since their first descriptions; only a few published reports, online images or videos of rarely encountered individual specimens exist. Dactylochlamys and Legendrea are also morphologically remarkable for their likely independently evolved tentacle-like structures. Recently, the first molecular data were published for the species L. loyezae. In our study, we present more robust phylogenetic analysis based on three molecular markers of Dactylochlamys pisciformis and all of the three known Legendrea species, showing that they likely represent a new anaerobic lineage of ciliates. We first provide a detailed morphological characterization of both genera using modern microscopy and staining methods. We identify and discuss the bacterial (Syntrophaceae) and archaeal endosymbionts harbored by both genera based on 16S rRNA gene sequences. We also discovered that Legendrea preys on gastrotrichs, which is supported by molecular data and a unique video material documenting the feeding behavior of one Legendrea species. This study brings essential information needed to better understand the phylogeny, life strategies, and rarity of these organisms and emphasizes the importance of citizen science. Abstract Free-living anaerobic ciliates are of considerable interest from an ecological and an evolutionary standpoint. Extraordinary tentacle-bearing predatory lineages have evolved independently several times within the phylum Ciliophora, including two rarely encountered anaerobic litostomatean genera, Legendrea and Dactylochlamys. In this study, we significantly extend the morphological and phylogenetic characterization of these two poorly known groups of predatory ciliates. We provide the first phylogenetic analysis of the monotypic genus Dactylochlamys and the three valid species of Legendrea based on the 18S rRNA gene and ITS-28S rRNA gene sequences. Prior to this study, neither group had been studied using silver impregnation methods. We provide the first protargol-stained material and also a unique video material including documentation, for the first time, of the hunting and feeding behavior of a Legendrea species. We briefly discuss the identity of methanogenic archaeal and bacterial endosymbionts of both genera based on 16S rRNA gene sequences, and the importance of citizen science for ciliatology from a historical and contemporary perspective.

Dataset Information

Conjugation in the spirotrich ciliate Halteria grandinella (Muller, 1773) Dujardin, 1841 (Protozoa, Ciliophora) and its phylogenetic implications.

Publications

Conjugation in the spirotrich ciliate Halteria grandinella (Müller, 1773) Dujardin, 1841 (Protozoa, Ciliophora) and its phylogenetic implications.

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