Choanoflagellate models — Monosiga brevicollis and Salpingoeca rosetta

Abstract

Choanoflagellates are the closest single-celled relatives of animals and provide fascinating insights into developmental processes in animals. Two species, the choanoflagellates Monosiga brevicollis and Salpingoeca rosetta are emerging as promising model organisms to reveal the evolutionary origin of key animal innovations. In this review, we highlight how choanoflagellates are used to study the origin of multicellularity in animals. The newly available genomic resources and functional techniques provide important insights into the function of choanoflagellate pre- and postsynaptic proteins, cell-cell adhesion and signaling molecules and the evolution of animal filopodia and thus underscore the relevance of choanoflagellate models for evolutionary biology, neurobiology and cell biology research.

Rosette Colonies of Choanoflagellates (Salpingoeca rosetta) Show Increased Food Vacuole Formation Compared with Single Swimming Cells

“…Choanoflagellates are of interest to evolutionary biologists as the potential evolutionary origin of metazoans (see these references for review, Hoffmeyer and Burkhardt ; King et al. ; Leadbeater ).…”

“…THE closest living relatives of animals, the choanoflagellates, are a diverse group of unicellular, flagellated protists, some species of which produce colonies. Research into the life cycle and feeding habits of this unicellular protist could elucidate the phylogenetic shift from unicellularity to multicellularity (see these references for review, Hoffmeyer and Burkhardt ; Leadbeater ). The choanoflagellate Salpingoeca rosetta displays both unicellular and colonial phases (Dayel et al.…”

Animal evolution coincides with a novel degree of freedom in exocytic transport processes

“…Our genome analysis and interaction data show that the FMN/SPIRE/MYO5 complex first comes into existence in holozoan sister taxa to metazoans, which represent the closest single cell relatives of animals. The cytoskeleton of choanoflagellates consists of cytoplasmic microtubule tracks just like vertebrate cells and also cortical actin structures, such as the actin-filled villi of the collar and filopodia extending from the basal pole of the cell (Hoffmeyer and Burkhardt 2016;Brunet and King 2017;Booth, et al 2018). Interestingly there are also actin filaments originating in the cell body, which coalesce at the base of the collar (Booth, et al 2018).…”

“…Their genomes encode proteins of the neuronal signalling machinery, such as voltage gated sodium and calcium channels (Cai 2008;Liebeskind, et al 2011;Gur Barzilai, et al 2012), synaptic scaffolding proteins (PSD95, Homer, Shank) and neurosecretory proteins (SNAREs and Munc18), which are part of the vesicle release machinery (Alie and Manuel 2010;Burkhardt, et al 2011;Burkhardt and Sprecher 2017). The latter localise to the apical membrane of the choanoflagellates and may mediate the release of molecules from vesicles (Hoffmeyer and Burkhardt 2016). The discovery of the neuronal signalling proteins in choanoflagellates raises the interesting question whether this novel protein machinery was the prerequisite for the evolution of sophisticated networks of animal cell communication.…”

Toward establishing model organisms for marine protists: Successful transfection protocols for Parabodo caudatus (Kinetoplastida: Excavata)

“…Transfection of two dinoflagellates has been successful using silicon carbide whiskers to deliver plasmid constructs (Te et al, 1998), and transfection of Perkinsus marinus, a marine protist parasite, has been achieved using electroporation (Fernandez-Robledo et al, 2008;Cold et al, 2016). Recent gene editing protocols have been established for few diatoms (Hopes et al, 2016;Liu et al, 2016), and progress toward useful forward genetics approaches for choanoflagellates have been established (Hoffmeyer and Burkhardt, 2016). Additional models are needed for more widely distributed, ecologically important free-living lineages.…”