Fig. 5

Proposed regulation of COTS spawning based on the gene expression profiles. (1) Physical seasonal environmental cues such as temperature and photoperiod trigger the commencement of gonad growth and gametogenesis and potentially sexually dimorphic gene expression. (2) Maturing individuals migrate towards shallow waters for spawning, with chemotaxis occurring along conspecific pheromone gradients. (3) Once aggregated, males initiate spawning based on abiotic and biotic (pheromones) cues. Spawning males release attractants and factors that trigger final oocyte maturation and spawning in females. (4) Females are competent to receive and transduce signals associated with the male spawn via receptors, hormones and neuropeptides in their sensory tentacles. (5) For both sexes, internal signalling cascades may include the secretion of neuropeptides, such as kisspeptin and SALMFamide, or a GnRH-like factor from sensory tentacles and radial nerves. (6) These may bind to cell-surface receptors on the coelomocytes, which may induce the secretion of RGP into the coelomic fluid. (7) RGP binds to cell-surface receptors on the gonads, (8) triggering the release of 1-methyladenine, which leads to oocyte maturation, the contraction of the gonad walls and the spawning of mature eggs