[Seminar] "Multigene phylogeny and expansion microscopy of Discocelia plataet sp. n., a new representative of a poorly characterized order Discocelida (Rhizaria: Cercozoa incertae sedis)" by Dr. Kristina Prokina

Speaker: Dr. Kristina Prokina, Ecologie Systématique et Evolution, Université Paris-Saclay [ESE][Google Scholar]

Title: Multigene phylogeny and expansion microscopy of Discocelia plataet sp. n., a new representative of a poorly characterized order Discocelida (Rhizaria: Cercozoa incertae sedis).

Abstract:

Cercozoa (Rhizaria, SAR) is one of the largest rhizarian subgroups and consists of a diverse assemblage of amoeboid and flagellated protists. They are ecologically significant in microbial food webs, widely diverse and even abundant in soils and deep marine sediments according to environmental sequencing. In spite of this, the cercozoan phylogeny remains poorly resolved by SSU rRNA gene analysis and -omics data are available for only a few well-characterized species.

Here, we present transcriptomic data from three newly isolated gliding monadofilosan strains: the glissomonad RAM19S6, the marimonad CRO19P5, and the discocelid GT001. Given its unique morphology, strain GT001 was extensively characterized using light and electron microscopy, leading to the description of a new species, Discocelia plataet sp. n. Ultrastructure expansion microscopy revealed the structure of its flagellar apparatus, allowing us to identify cercozoan microtubular root homologies and supplement our knowledge on the discocelid cell structure with new details. D. plataet is distinguished by the absence of a body tip and velum tip, the presence of an acronema on the posterior flagellum, and a smaller cell size. We discuss the phylogenetic placement of new strains within Monadofilosa and the evolutionary context of Discocelida, expanding our understanding of cercozoan diversity and phylogeny.