What is it about?
Biological form is integrally tied to function, and all organisms across the tree of life acquire their morphological features through developmental processes. Our understanding of cell development and morphogenesis focuses primarily on the differentiation of cell types within multicellular organisms, but most biological diversity is made up of unicellular organisms. Here, we describe a type of unicellular organism, a ciliate called Euplotes gigatrox that undergoes drastic morphological transformations within a genetically uniform population, the most spectacular being the appearance of “supergiants.” These supergiants increase in size, change shape, and modify their locomotion and feeding behavior to cannibalize clonal relatives. We explore supergiant formation from the perspective of life cycle, ecological strategy, and gene expression, altogether demonstrating that supergiants are a distinct, regulated, transcriptionally unique stage. Differentiation appears to depend on internal and external conditions, suggesting that regulatory loops have evolved to ensure coupling between environmental and physiological conditions.
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Why is it important?
Development in microbial eukaryotes (protists), which can rival the morphological complexity of small animals, is largely unexplored. We report here on the finding that in clonal populations of the ciliate Euplotes gigatrox a small number of cells can develop into cannibalistic “supergiants” that drastically change size, shape, and behavior, transitioning from filter feeders to raptorial predators that can consume their kin. This process involves phenotypic tradeoffs and a system of regulatory loops consistent with a bet-hedging mechanism tuned to fluctuating environmental conditions. Our work introduces insights and approaches for studying morphogenesis and behavior in complex, unicellular organisms, complementing traditional studies of animal evolutionary developmental biology and cell differentiation. This system provides a blueprint for approaching both cell differentiation and functional ecology in unicellular organisms, which might open new avenues for the generalization and contextualization of known morphogenetic mechanisms, as well as the discovery of new ones.
Perspectives
This article was the product of a fun, long-term collaboration. It was very satisfying to have the opportunity to bring an organism into the lab from a wild field sample and to begin to use its unusual biological features to begin to learn fundamental principles of the regulation and evolution of cell shape and behavior. Our lab continues to work with the organism that this work focuses on, and we expect that this is only the beginning of insights from this fascinating critter.
Ben Larson
Rensselaer Polytechnic Institute
Read the Original
This page is a summary of: Regulated development of cannibalistic supergiant cells in the ciliate
Euplotes gigatrox, Proceedings of the National Academy of Sciences, May 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2606891123.
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