Biology subjects

Rutaganira, F. U.

Publications and source records attributed to Rutaganira, F. U..

3 recordsLinked to original sources

bioRxiv2026

An accessible transfection protocol for choanoflagellates

Choanoflagellate genetics has undergone rapid and impactful developments in the last decade. Currently, the primary method for genetic modification of choanoflagellates relies on proprietary nucleofection reagents to deliver transgenes for ectopic expression or CRISPR-Cas9 ribonucleoprotein complexes for targeted genome editing. The acquisition of proprietary buffers required for nucleofection can hamper advances in choanoflagellate research due to costs, shipping limitations, and restrictions that prevent buffer components from being optimized for understudied organisms. Therefore, we test whether a low-cost in-house electroporation buffer developed for other systems can replace the proprietary buffer currently used for choanoflagellate transfection. Here, we present an in-house buffer with transfection efficiency comparable to that of the previously established proprietary buffer. This work increases the accessibility of choanoflagellate genetics and can broaden research participation in investigating animal origins.

evolutionary biology↗

bioRxiv2025

Looks can be deceiving: discordances in phylogeny and morphology within loricate choanoflagellates

Choanoflagellates are heterotrophic holozoans that are classified into two groups based on their morphology: loricates, which possess a silica-based extracellular structure, and craspedids, which do not. Although the craspedid versus loricate morphological separation is currently supported by their phylogenetic relationship, recent evidence has suggested inconsistencies between morphology and phylogeny within each group. Loricate choanoflagellate taxonomy has historically been based on selected aspects of their lorica morphology, and on their mode of cell division, in which tectiform daughter cells emerge into a lorica synthesized by their mother cell following division, and nudiform daughter cells do not. Here, we characterize two new loricate strains that display unexpected morphological features when compared to their nearest genetic relatives. The strain BEAP0094 very closely matched the 18S ribosomal gene of the tectiform Pseudostephanoeca paucicostata, but its morphology clearly differed, due to the absence of the characteristic anterior ring found in all Stephanoeca species. Instead, its features resembled more closely those of the Acanthocorbis genus, raising the possibility of the existence of either multiple lorica morphologies within the same or very closely related species, or multiple morphological species sharing the same 18S ribosomal gene. The second strain we investigated, BEAP0360, presented a morphological match to Stephanoeca cauliculata, but its 18S ribosomal sequence did not, suggesting that different species could share the same lorica architecture. BEAP0360, here described as Cepoeca plumata (n. gen. n. sp.), possesses a key phylogenetic placement, potentially as the earliest branching member within nudiform loricates, which would be informative for investigating the evolution of the nudiform lifestyle. Our findings are inconsistent with a strict classification based on currently defined aspects of lorica morphology and support the usage of genetic data as primary criterion for genus-level taxonomic assignment.

evolutionary biology↗

bioRxiv2024

Glycerol improves the viability of a cryopreserved choanoflagellate

The colonial choanoflagellate Salpingoeca rosetta is a tractable model system for studying the origins of multicellularity, but long-term storage strategies for this species have not been tested. In this study, we probed each stage of cryopreservation (freeze-down, long-term storage, recovery) to identify the optimal protocol for recovery of S. rosetta and co-cultured bacterial cells. Dimethyl sulfoxide (Me2SO; commonly referred to as DMSO), the current cryoprotective agent (CPA) standard, proved to be worse than glycerol at comparable concentrations. Samples treated with either CPA at 5% showed the poorest recovery. Our results identified 15% glycerol as the most effective CPA for both S. rosetta and Echinicola pacifica. We also determined that ultra-low temperature freezers can be sufficient for short-term storage. We propose 15% glycerol and liquid phase nitrogen as the standard cryopreservation protocol for S. rosetta cultures and as a starting point for testing long-term storage strategies for other choanoflagellates and heterotrophic protists.

developmental biology↗