Sensory conflict disrupts circadian rhythms in the sea anemone Nematostella vectensis

Abstract

Circadian clocks allow organisms to optimize their phenotypes in relation to rhythmic environmental conditions. Clocks must synchronize, or entrain, to environmental signals called zeitgebers (such as light and temperature) while maintaining internal rhythms that are robust to environmental noise. We know surprisingly little about how clocks function in the presence of multiple zeitgebers, although these are the conditions that exist in nature. Misalignment between zeitgeber cycles (here, "sensory conflict") can disrupt circadian rhythms in behavior and gene expression, but it is not clear whether this is generally true across animals. In order to understand general rules about animal clocks, and how clocks have evolved throughout Metazoa, it is necessary to study non-bilaterian animals such as cnidarians, which include corals, jellies, and sea anemones. The sea anemone Nematostella vectensis has emerged as the principal model system for cnidarian circadian biology. In this study, we show that temperature cycles entrain circadian locomotor rhythms in Nematostella, and then conduct extensive behavioral experiments across a range of light and temperature cycles to show that Nematostella's circadian behavior is disrupted by sensory conflict. Chronic exposure to conflicting light and temperature cycles also causes substantial changes to the rhythmic transcriptome, including the breakdown of rhythmic expression of various metabolic processes. These results have important implications for our understanding of cnidarian circadian clocks at both the molecular and organismal levels, and for how sensory information is processed by clocks in the absence of a central nervous system.

Sensory conflict disrupts circadian rhythms in the sea anemone Nematostella vectensis

“…The DLC algorithm was trained on this dataset for 600,000 iterations using default settings and the ‘resnet_50’ neural network. DLC output files were analyzed using R code derived from the DLCAnalyzer Github package ( https://github.com/ETHZ-INS/DLCAnalyzer ; Sturman et al, 2020 ; von Ziegler and Roessler, 2023 ); custom code used for this paper is available at this github repository: https://github.com/caberger1/Sensory-Conflict-in-Nematostella-vectensis (copy archived at Berger, 2023 ). Frames with a likelihood less than 0.90 were removed and interpolated, as were frames where the recorded movement was more than per frame.…”

“…Raw RNA-seq data have been uploaded to the NCBI Sequence Read Archive (SRA), Bioproject PRJNA826898. R code used for analysis is available at https://github.com/caberger1/Sensory-Conflict-in-Nematostella-vectensis (copy archived at Berger, 2023 ).…”