Sea anemones may look simple, but their biology tells a far more complex story. This Open Biology study uncovers how specialised stinging cells used for prey capture and defence, are regulated at a deeper level than ever before.
What is this study about?
Sea anemones, corals and jellyfish belong to one of the oldest animal lineages on Earth, yet they possess one of the most striking cellular innovations in biology: the cnidocyte, or stinging cell. These microscopic structures, capable of explosively releasing venom or entangling prey, have long fascinated biologists. In a recent study published in , Kozlovski et al. provide fresh insight into how these remarkable cells are regulated at the level of chromatin, revealing an unexpected degree of complexity underlying their formation and function.
Cnidocytes are highly specialised cells that exist in several forms, including venom-injecting nematocytes and adhesive spirocytes. Previous work has largely focused on identifying the genes and transcription factors involved in their development. However, gene expression represents only part of the picture. A key outstanding question has been how these gene expression programmes are controlled. In this study, the authors take an important step forward by integrating transcriptomic data with epigenomic profiling in the sea anemone Nematostella vectensis. By mapping histone modifications associated with active regulatory regions, they identify the promoters and enhancers that underpin cnidocyte-specific gene expression. Notably, this represents the first cell-type-specific analysis of chromatin regulation in cnidocytes, providing a framework for linking gene activity to its regulatory architecture.
What makes these findings significant?
The study reveals that cnidocytes are not only diverse in form and function, but also in the regulatory programmes that define them. Distinct cnidocyte subtypes are associated with unique sets of regulatory elements, demonstrating that chromatin landscapes play a central role in specifying cell identity.
Among the most intriguing findings is the identification of a previously unrecognised nematocyte population that expresses a specific toxin (Nep3) while lacking many others. This suggests that even within seemingly well-characterised cell types, there remains hidden diversity that can only be uncovered through integrative approaches. More broadly, the work highlights the importance of chromatin-level regulation. While transcription factors have long been considered key drivers of cell fate, this study shows that histone modifications and regulatory DNA elements provide an additional and essential layer of control- one that may, in some cases, define cell identity more clearly than gene expression alone.
.jpg)
Why is this important in a wider context?
Cnidocytes are often cited as a textbook example of evolutionary novelty. Understanding how such specialised cells arise, diversify, and are maintained offers insight into one of the central questions in biology: how new cell types evolve. By demonstrating that complex regulatory landscapes are already present in early-branching animals, this study suggests that the interplay between chromatin and gene expression is an ancient and fundamental feature of animal biology. It also underscores the growing recognition that noncoding regions of the genome once considered “junk DNA”, play a critical role in shaping cellular diversity and function.
What next?
The approaches developed here open the door to a range of future studies. Comparative analyses across species could reveal how regulatory elements evolve alongside new cell types, while emerging single-cell multi-omics technologies may further resolve the diversity and developmental trajectories of cnidocytes. Beyond cnidarians, the work provides a valuable methodological blueprint for investigating gene regulation in other non-traditional model systems.
About the authors
This work was carried out by researchers at the Hebrew University of Jerusalem, led by Itamar Kozlovski and . Their research focuses on the evolution and molecular biology of cnidarians, with Nematostella vectensis serving as a key model for understanding the origins of cellular diversity.
is seeking high-quality research articles across cellular and molecular biology. Find out more about our and .
Image captions:
Adult Nematostella vectensis sea anemone expressing the fluorescent reporter mOrange2 under control of the cnidocyte-specific structural minicollagen (Ncol3) promoter. Credit: Itamar Kozlovski.
Header image: Various examples of sea anemones (1893 print) by Giacomo Merculiano. Wikimedia Commons
