Linking the molecular bases of endogenous time keeping and ecdysis: How lunar and tidal clocks control the moulting rhythms in a Crustacean

• Applicant: Dr. Jule Neumann
• Subject Area: Animal Physiology and Biochemistry ; Developmental Biology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556460766

The research project is pioneering the investigation of the relationship between two fundamentally important processes, namely endogenous time keeping and periodic moulting (ecdysis) in arthropods - a task yet to be attempted but that could reshape our text-book knowledge of arthropod success. Arthropods form the most diverse and important multicellular group in the animal kingdom and inevitably shape the ecosystems of our planet. Because they have an exoskeleton, regular moulting is arguably the most important event during their life-history and therefore in the animal world. However, the temporal regulation of this phenomenon is still unknown. It is crucial for organisms to synchronise their moult with the most favourable environmental conditions in order to maximise their fitness. For this reason, organisms have evolved endogenous molecular timekeeping mechanisms known as biological clocks. These include the daily clock (circadian, 24h), the tidal clock (circatidal, 12.4h) and the lunar clocks (circalunar, 30d & circasemilunar, 15d). Research into the connection between these two evolutionary inventions, periodic moulting and biological clocks, is one of the great questions of our time. How the tidal and lunar clocks control ecdysis at the molecular and cellular level has, to our knowledge, not yet been investigated in any organism. The green shore crab Carcinus maenas, native to Europe, is an emerging model organism for arthropods, but also a highly invasive, cosmopolitan species that has been shown to negatively and profoundly alter ecosystems. C. maenas is well-studied on the behavioural level with respect to its circadian (24h) and circatidal (12.4h) clock. However less heeded and our focus is its semilunar (15d) ecdysis rhythm synchronised to spring and neap tides. The aim of the research project proposed here is therefore to establish an ecdysis-clock study system that not only allows evolutionary comparisons across the animal kingdom, but also reveals the molecular architecture of the still enigmatic tidal and lunar clock. We will characterize the lunar and tidal ecdysis rhythm from the behavioural to the molecular level in C. maenas. First, we characterise the lunar dimension of ecdysis and define it as being under endogenous clock control using chronobiological behavioural assays. Second, we use time-course transcriptome profiling (RNA-Seq) over tidal and lunar timescales to reveal rhythmic genes betraying the clock and clock-controlled mechanisms. Third, we synergise these approaches to yield detailed anatomical localization of putative clock and endocrine factors, at the mRNA and protein level in the nervous system using HCR-ISH combined with immunohistochemistry. Deciphering the molecular relationship between endogenous timing and moulting in an invasive arthropod will expand the methodological approaches of pest management and control in conservation and invasion biology, and is thus also relevant for fisheries and aquaculture.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Dr. David Wilcockson, Ph.D.