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ArticleChromatin dynamics and gene expression response to heat exposure in field-conditioned versus laboratory-cultured Nematostella vectensis(MDPI, 2021-07-12) Weizman, Eviatar N. ; Rinsky, Mieka ; Simon-Blecher, Noa ; Lampert-Karako, Sarit ; Yaron, Orly ; Tarrant, Ann M. ; Levy, OrenOrganisms’ survival is associated with the ability to respond to natural or anthropogenic environmental stressors. Frequently, these responses involve changes in gene regulation and expression, consequently altering physiology, development, or behavior. Here, we present modifications in response to heat exposure that mimics extreme summertime field conditions of lab-cultured and field-conditioned Nematostella vectensis. Using ATAC-seq and RNA-seq data, we found that field-conditioned animals had a more concentrated reaction to short-term thermal stress, expressed as enrichment of the DNA repair mechanism pathway. By contrast, lab animals had a more diffuse reaction that involved a larger number of differentially expressed genes and enriched pathways, including amino acid metabolism. Our results demonstrate that pre-conditioning affects the ability to respond efficiently to heat exposure in terms of both chromatin accessibility and gene expression and reinforces the importance of experimentally addressing ecological questions in the field.
ArticleTidal and diel orchestration of behaviour and gene expression in an intertidal mollusc(Nature Publishing Group, 2018-03-20) Schnytzer, Yisrael ; Simon-Blecher, Noa ; Li, J. ; Ben-Asher, H. Waldman ; Salmon-Divon, Mali ; Achituv, Yair ; Hughes, Michael E. ; Levy, OrenIntertidal inhabitants are exposed to the 24-hour solar day, and the 12.4 hour rising and falling of the tides. One or both of these cycles govern intertidal organisms’ behaviour and physiology, yet little is known about the molecular clockworks of tidal rhythmicity. Here, we show that the limpet Cellana rota exhibits robust tidally rhythmic behaviour and gene expression. We assembled a de-novo transcriptome, identifying novel tidal, along with known circadian clock genes. Surprisingly, most of the putative circadian clock genes, lack a typical rhythmicity. We identified numerous tidally rhythmic genes and pathways commonly associated with the circadian clock. We show that not only is the behaviour of an intertidal organism in tune with the tides, but so too are many of its genes and pathways. These findings highlight the plasticity of biological timekeeping in nature, strengthening the growing notion that the role of ‘canonical’ circadian clock genes may be more fluid than previously thought, as exhibited in an organism which has evolved in an environment where tidal oscillations are the dominant driving force.
ArticleProfiling molecular and behavioral circadian rhythms in the non-symbiotic sea anemone Nematostella vectensis(Nature Publishing Group, 2015-06-17) Oren, Matan ; Tarrant, Ann M. ; Alon, Shahar ; Simon-Blecher, Noa ; Elbaz, Idan ; Appelbaum, Lior ; Levy, OrenEndogenous circadian clocks are poorly understood within early-diverging animal lineages. We have characterized circadian behavioral patterns and identified potential components of the circadian clock in the starlet sea anemone, Nematostella vectensis: a model cnidarian which lacks algal symbionts. Using automatic video tracking we showed that Nematostella exhibits rhythmic circadian locomotor activity, which is persistent in constant dark, shifted or disrupted by external dark/light cues and maintained the same rate at two different temperatures. This activity was inhibited by a casein kinase 1δ/ε inhibitor, suggesting a role for CK1 homologue(s) in Nematostella clock. Using high-throughput sequencing we profiled Nematostella transcriptomes over 48 hours under a light-dark cycle. We identified 180 Nematostella diurnally-oscillated transcripts and compared them with previously established databases of adult and larvae of the symbiotic coral Acropora millepora, revealing both shared homologues and unique rhythmic genes. Taken together, this study further establishes Nematostella as a non-symbiotic model organism to study circadian rhythms and increases our understanding about the fundamental elements of circadian regulation and their evolution within the Metazoa.