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. 2019 Jul 3;8:e46113. doi: 10.7554/eLife.46113

Figure 1. Simplified overview of the neuropeptide/hormone signalling pathway at moulting.

Figure 1.

PTTH initiates a signalling cascade that results in the biosynthesis of ecdysone. The decline of the ecdysone titre triggers the release of ETH that, in turn, causes the release of EH. These two hormones mutually enhance one another in a positive feedback loop to control and regulate pre-ecdysis behaviour. With the ensuing release of CCAP, caused by EH, pre-ecdysis ceases and the ecdysis motor program is started. Finally, bursicon responds to the increasing levels of CCAP and initiates post-ecdysis behaviour and cuticle tanning. This figure is based on the studies of McNabb et al. (1997) and Clark et al. (2004). Animal silhouettes were obtained under Public Domain licence at phylopic (http://phylopic.org/), unless otherwise indicated. Beetle: T. Michael Keesey after Ponomarenko (available for reuse under https://creativecommons.org/publicdomain/zero/1.0/); moth: by Gareth Monger (available for reuse under https://creativecommons.org/licenses/by/3.0/); Drosophila: Thomas Hegna (available for reuse under https://creativecommons.org/publicdomain/zero/1.0/).