Cell size and dorsal cilia: are they useful features for the identification of Stylonychia mytilus (Ciliophora, Spirotrichea) and its subpopulations?

It was investigated whether (1) the number of cilia of the dorsal kineties 3 and 4 and (2) the cell length are species-specific characters which can be used to distinguish the sibling species S. mytilus and S. lemnae.

[Stylonychia lemnae as a model organism for studies of macronuclear minichromosomes of the ciliates].

The unique structural and functional organization of macronuclear (somatic nucleus) genome of the spirotrichous ciliates, exemplified by Stylonychia lemnae, has been reviewed. Data on the architecture of S. lemnae nuclear apparatus at interphase and during vegetative cell division, conjugation or autogamy are summarized.

alpha-tubulin minichromosome promoters in the stichotrichous ciliate Stylonychia lemnae.

Ciliated protists are model organisms for a number of molecular phenomena including telomerase function, self-splicing introns, and an RNA interference-related mechanism in programmed DNA elimination. Despite this relevance, our knowledge about promoters and transcriptional regulation in these organisms is very limited. The macronuclear genome of stichotrichous ciliates consists of minichromosomes which typically encode a single gene.

A PCR-based method to distinguish the sibling species Stylonychia mytilus and Stylonychia lemnae (Ciliophora, Spirotrichea) using isocitrate dehydrogenase gene sequences.

A differentiation, based on morphological characters, between Stylonychia mytilus and Stylonychia lemnae is very difficult, especially for non-specialists. These two sibling species were considered as one species, S. mytilus, until detailed cytological and genetic studies could show the existence of two genetically isolated varieties.

Stylonychia lemnae strains from a North American site differ in a single nucleotide within the small subunit rDNA from Eurasian strains.

Stylonychia lemnae (Ciliophora, Spirotrichea), a member of the Stylonychia mytilus complex, shows a global distribution, occurring in many temperate fresh waters. As there are few descriptions of biogeographical patterns of ubiquitously occurring ciliated protozoans, we report a distinct sequence difference within the small subunit ribosomal DNA gene, which occurs only in the clones of S. lemnae isolated from the surroundings of Ithaca (USA) in comparison with clones of the same species from different regions in Europe, Asia, and South Africa.