Morpholino-Mediated Knockdown of Ciliary Genes in Euplotes vannus, a Novel Marine Ciliated Model Organism

Abstract

Cilia are highly conserved organelles present in almost all types of eukaryotic cells, and defects in cilia structure and/or function are related to many human genetic disorders. Single-celled ciliated protists, which possess diverse types of cilia, are remarkable model organisms for studying cilia structures and functions. Euplotes vannus is a representative ciliate with many intriguing features; for example, it possesses extensively fragmented somatic genomes and a high frequency of + 1 programmed ribosomal frameshifting. However, the molecular mechanisms underlying these remarkable traits remain largely unknown, mainly due to the lack of efficient genetic manipulation tools. Here, we describe the first application of a morpholino-based strategy to knockdown gene expression in E. vannus. Through interfering with the function of two ciliary genes, ZMYND10 and C21ORF59, we showed that these two genes are essential for the ciliary motility and proliferation of E. vannus cells. Strikingly, both ZMYND10-and C21ORF59knockdown cells developed shorter cilia in the ventral cirri, a special type of ciliary tuft, suggesting a novel role for these genes in the regulation of cilia length. Our data provide a new method to explore gene function in E. vannus, which may help us to understand the functions of evolutionarily conserved cilia-related genes as well as other biological processes in this intriguing model.

Analysis of autapomorphic point mutations provides a key for the tangled taxonomic distinction of the closely related species, Euplotes crassus, E. minuta and E. vannus (Ciliophora, Euplotida)

“…They dwell in sympatry in the sandy interstices of the eulittoral zone, and share the same two basic diagnostic traits of the Euplotes taxonomy, i. e. a single-type dargyrome and 10 fronto-ventral cirri (cirrotype-10). Over the years, the experimental utilization of E. crassus, E. minuta and E. vannus has rapidly been widened: first, to various aspects of their breeding patterns and reproductive biology involving autogamy (self-fertilization) in addition to mating (Dini 1984;Dini and Luporini 1980;Luporini 1970;Siegel and Heckmann 1966); then, to a broad spectrum of research fields including molecular genetics (Alimenti et al 2011;Klobutcher and Farabaugh 2002;Klobutcher et al 1981;Roth and Prescott 1985;Tang et al 2020;Vallesi et al 2014), evolution of the genetic code (Lozupone et al 2001;Turanov et al 2009), chemistry of secondary metabolites (Guella et al 2010) and, most recently, organization of the nuclear and mitochondrial genomes (Chen et al 2019;de Graaf et al 2009;Huang et al 2021;Lobanov et al 2017).…”

Feeding flow and membranelle filtration in ciliates

“…We have chosen to focus on E. vannus to explore a representative upstream collecting ciliate. The cell is elongated and flattened, and there is a clear differentiation between the dorsal and ventral side [31][32][33]. On the ventral side, the cell has approximately 20 cirri and a band of membranelles.…”