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1. Environmental and molecular regulation of asexual reproduction in the sea anemone Nematostella vectensis

   https://doi.org/10.1098/rsos.230152  

   Al-Shaer, Layla ; Leach, Whitney ; Baban, Noor ; Yagodich, Mia ; Gibson, Mathew C. ; Layden, Michael J. ( June 2023 , Royal Society Open Science)

   Cnidarians exhibit incredible reproductive diversity, with most capable of sexual and asexual reproduction. Here, we investigate factors that influence asexual reproduction in the burrowing sea anemoneNematostella vectensis,which can propagate asexually by transverse fission of the body column. By altering culture conditions, we demonstrate that the presence of a burrowing substrate strongly promotes transverse fission. In addition, we show that animal size does not affect fission rates, and that the plane of fission is fixed along the oral–aboral axis of the polyp. Homeobox transcription factors and components of the TGFβ, Notch, and FGF signalling pathways are differentially expressed in polyps undergoing physal pinching suggesting they are important regulators of transverse fission. Gene ontology analyses further suggest that during transverse fission the cell cycle is suppressed, and that cell adhesion and patterning mechanisms are downregulated to promote separation of the body column. Finally, we demonstrate that the rate of asexual reproduction is sensitive to population density. Collectively, these experiments provide a foundation for mechanistic studies of asexual reproduction inNematostella,with implications for understanding the reproductive and regenerative biology of other cnidarian species.

    

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2. A novel regulatory gene promotes novel cell fate by suppressing ancestral fate in the sea anemone Nematostella vectensis

   https://doi.org/10.1073/pnas.2113701119  

   Babonis, Leslie S. ; Enjolras, Camille ; Ryan, Joseph F. ; Martindale, Mark Q. ( May 2022 , Proceedings of the National Academy of Sciences)

   Cnidocytes (i.e., stinging cells) are an unequivocally novel cell type used by cnidarians (i.e., corals, jellyfish, and their kin) to immobilize prey. Although they are known to share a common evolutionary origin with neurons, the developmental program that promoted the emergence of cnidocyte fate is not known. Using functional genomics in the sea anemone, Nematostella vectensis , we show that cnidocytes develop by suppression of neural fate in a subset of neurons expressing RFamide. We further show that a single regulatory gene, a C 2 H 2 -type zinc finger transcription factor (ZNF845), coordinates both the gain of novel (cnidocyte-specific) traits and the inhibition of ancestral (neural) traits during cnidocyte development and that this gene arose by domain shuffling in the stem cnidarian. Thus, we report a mechanism by which a truly novel regulatory gene (ZNF845) promotes the development of a truly novel cell type (cnidocyte) through duplication of an ancestral cell lineage (neuron) and inhibition of its ancestral identity (RFamide). 

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3. The starlet sea anemone, Nematostella vectensis , possesses body region-specific bacterial associations with spirochetes dominating the capitulum

   https://doi.org/10.1093/femsle/fnab002  

   Bonacolta, Anthony M ; Connelly, Michael T ; M. Rosales, Stephanie ; del Campo, Javier ; Traylor-Knowles, Nikki ( February 2021 , FEMS Microbiology Letters)

   ABSTRACT Sampling of different body regions can reveal highly specialized bacterial associations within the holobiont and facilitate identification of core microbial symbionts that would otherwise be overlooked by bulk sampling methods. Here, we characterized compartment-specific associations present within the model cnidarian Nematostella vectensis by dividing its morphology into three distinct microhabitats. This sampling design allowed us to uncover a capitulum-specific dominance of spirochetes within N. vectensis. Bacteria from the family Spirochaetaceae made up 66% of the community in the capitulum, while only representing 1.2% and 0.1% of the communities in the mesenteries and physa, respectively. A phylogenetic analysis of the predominant spirochete sequence recovered from N. vectensis showed a close relation to spirochetes previously recovered from wild N. vectensis. These sequences clustered closer to the recently described genus Oceanispirochaeta, rather than Spirochaeta perfilievii, supporting them as members of this clade. This suggests a prevalent and yet uncharacterized association between N. vectensis and spirochetes from the order Spirochaetales. 

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4. VARIATION IN CONTRIBUTIONS OF ASEXUAL REPRODUCTION TO THE GENETIC STRUCTURE OF POPULATIONS OF THE SEA ANEMONE METRIDIUM SENILE

   https://doi.org/10.1111/j.1558-5646.1986.tb00477.x  

   Hoffmann, Richard J. ( March 1986 , Evolution)
5. The mitochondrial genome of a sea anemone Bolocera sp. exhibits novel genetic structures potentially involved in adaptation to the deep-sea environment

   https://doi.org/10.1002/ece3.3067  

   Zhang, Bo ; Zhang, Yan-Hong ; Wang, Xin ; Zhang, Hui-Xian ; Lin, Qiang ( July 2017 , Ecology and Evolution)