Chemicals released by male sea cucumber mediate aggregation and spawning behaviours

Abstract

The importance of chemical communication in reproduction has been demonstrated in many marine broadcast spawners. However, little is known about the use of chemical communication by echinoderms, the nature of the compounds involved and their mechanism(s) of action. Here, the hypothesis that the sea cucumber Holothuria arguinensis uses chemical communication for aggregation and spawning was tested. Water conditioned by males, but not females, attracted both males and females; gonad homogenates and coelomic fluid had no effect on attraction. Male spawning water, but not female spawning water, stimulated males and females to release their gametes; the spermatozoa alone did not induce spawning. H. arguinensis male spawning water also induced spawning in the phylogenetically related H. mammata. This indicates that males release pheromones together with their gametes that induce spawning in conspecifics and possibly sympatric species. Finally, the male pheromone seems to be a mixture with at least one labile compound (biological activity is lost after four hours at ambient temperature) possibly including phosphatidylcholines. The identification of pheromones in sea cucumbers offers a new ecological perspective and may have practical applications for their aquaculture.

Gonad development and spawning of the Vulnerable commercial sea cucumber, Stichopus herrmanni, in the southern Great Barrier Reef

“…Observations in the Solomon Islands indicate that H. scabra are normally scattered but progressively form pairs, trios and larger groups, peaking a few days before the new moon. Pheromones released by males have been shown to induce aggregation and spawning in H. arguinensis and sympatric holothuroids (Marquet et al , 2018). Aggregative spawning is suggested to be an evolved strategy to increase fertilization rates and reduce predation of gametes through predator satiation (Babcock et al , 1992).…”

“…Aggregative spawning is suggested to be an evolved strategy to increase fertilization rates and reduce predation of gametes through predator satiation (Babcock et al , 1992). As for S. herrmanni , males spawn prior to females in other aspidochirotids (Babcock et al , 1992; Morgan, 2000; Hamel et al , 2001; Marquet et al ., 2018). Males release sperm over long periods in contrast to the short bursts of egg release by females (Babcock et al , 1992).…”

Deletion of iRhom2 protects against diet-induced obesity by increasing thermogenesis

“…Consequently, the phenotype of iRhom2 KO mice is much milder than ADAM17 KO mice, which die perinatally with severe abnormalities in the eyes, skin, hair, and lung [36]. By contrast, iRhom2 KO mice appear normal but are protected from a range of conditions, most of which involve inflammation, including sepsis [21,22], arthritis [37], and lung injury [38]. However, whether global deletion of iRhom2 impacts energy balance and/or adipose tissue function is currently unknown.…”

Localization and distribution of nitric oxide synthase and other neuronal markers in the podia of Holothuria arguinensis

“…(e.g., Ullrich‐Lüter et al., 2011; VandenSpiegel et al., 1995). This idea is supported by numerous studies demonstrating that they perceive and respond to waterborne stimuli from predators, damaged conspecifics, potential food sources, and conspecific mates (e.g., Caballes & Pratchett, 2017; Campbell, Coppard, D'Abreo, & Tudor‐Thomas, 2001; Cyrus, Bolton, Scholtz, & Macey, 2015; Dix, 1969; Hamel & Mercier, 1996; Mann, Wright, Welsford, & Hatfield, 1984; Marquet, Hubbard, da Silva, Afonso, & Canário, 2018; Soong, Chang, & Chao, 2005; Unger & Lott, 1994). However, the sensory structures involved in the detection of chemical cues have not yet been identified.…”