Immunocytochemical localization of the neuropeptide S1 and serotonin in larvae of the starfishPisaster ochraceusandAsterias rubens

Abstract

Studies of the larval nervous system of two species of starfish were carried out using antisera to a recently isolated native echinoderm neuropeptide, GFNSALMFamide (S1), and to serotonin. S1-like immunoreactivity was found in the larvae of the asteroids Pisaster ochraceus and Asterias rubens (Echinodermata: Asteroidea), originating in the apical region and becoming concentrated as two groups of cells in the dorsal ciliary band, the preoral transverse and adoral ciliary bands in larvae up to the early brachiolarian stage (five weeks). The pattern of serotonin immunoreactivity, although appearing earlier in the apical nerve plexus, is very similar to that of the peptide, with paired groups of immuno- reactivity apparent in the dorsal ciliary band. This evidence, together with other recent studies, indicates that this neuropeptide is present in both the larval and adult nervous system, despite the complete reformation of the system at metamorphosis. The close localization of SI with serotonin may also suggest a possible function for the peptide in larval and adult nervous systems.

Development and distribution of the peptidergic system in larval and adult Patiriella: Comparison of sea star bilateral and radial nervous systems

“…The nervous systems of the planktotrophic larvae of marine invertebrates have many similarities, including the presence of anterior ganglia, innervation of ciliary structures, and expression of a similar suite of neurochemicals (Barlow and Truman, 1991;Moss et al, 1994;Lin and Leise 1966;Kempf et al, 1997;Marois and Carew, 1997a-c;Byrne et al, 1999Byrne et al, , 2001Dickinson et al, 1999;Hay-Schmidt, 2000). These commonalties across phylogenetically disparate taxa suggest strong convergence in the evolution of nervous system development in response to selection pressures specific to the planktonic environment (Kempf et al, 1997;Marois and Carew, 1997a;Hadfield, 2000).…”

“…Scale bars ϭ 40 m in a, 100 m in b. ciliated bands has focussed on Garstang's hypothesis (Garstang, 1894) that the chordate nerve cord was derived from the ciliated band of an ancestral larva similar to the echinoderm dipleurula (Lacalli, 1994;Hay-Schmidt, 2000). Immunocytochemical studies show an extensive array of neurochemicals associated with echinoderm ciliated bands, including serotonin, ␥-aminobutyric acid (GABA), dopamine, and SALMFamides (Burke et al, 1986; Bisgrove and Burke, 1987;Nakajima et al, 1993;Moss et al, 1994;Chen et al, 1995;Chee and Byrne, 1999a,b;Beer et al, 2001;Cisternas et al, 2001). S1-positive cells, such as those associated with the ciliated bands of P. regularis, are also associated with the ciliated bands of ophiuroid and echinoid plutei (Thorndyke et al, 1992;Beer et al, 2001;Cisternas et al, 2001).…”

“…SALMFamides are widespread in the echinoderm nervous system and have been localised in the neural tissue of most of the echinoderm classes (Moore and Thorndyke, 1993;Ghyoot et al, 1994;Moss et al, 1994;Díaz-Miranda et al, 1995;Newman et al, 1995a;Byrne et al, 1999Byrne et al, , 2001Beer et al, 2001;Byrne, 2001;Cisternas et al, 2001). Antisera generated against these peptides were used as markers in the studies cited above to investigate the distribution of neuronal tissue in developing and adult echinoderms.…”

“…The SALMFamides by contrast are present in the nervous systems of both echinoderm life stages (Moore and Thorndyke, 1993;Moss et al, 1994;Newman et al, 1995a;Byrne et al, 1999Byrne et al, , 2001Beer et al, 2001). It has been suggested that the presence of GFNSALMFamide 1 (S1)-like immunoreactivity in larval and adult asteroids might provide a tool with which to trace development of the juvenile nervous system through metamorphosis (Moss et al, 1994;Byrne et al, 1999). Among invertebrates, the change from the bilaterally symmetrical nervous system of free-swimming echinoderm larvae to the radial nervous system of benthic adults during metamorphosis is striking.…”

Discovery of a second SALMFamide gene in the sea urchin Strongylocentrotus purpuratus reveals that L-type and F-type SALMFamide neuropeptides coexist in an echinoderm species

“…digestive system) and skeletal systems (e.g. the locomotory organs, tube feet) [7][8][9][10][11]. Likewise, antibodies to the holothurian neuropeptide GFSKLYFamide revealed a widespread pattern of expression in Holothuria glaberrima [12], indicating that SALMFamide neuropeptides may have general roles as neurotransmitters or neuromodulators in echinoderms.…”