Nervous system development of the sea cucumber Stichopus japonicus

Abstract

The nervous system development of the sea cucumber Stichopus japonicus was investigated to explore the development of the bilateral larval nervous system into the pentaradial adult form typical of echinoderms. The first nerve cells were detected in the apical region of epidermis in the late gastrula. In the auricularia larvae, nerve tracts were seen along the ciliary band. There was a pair of bilateral apical ganglia consisted of serotonergic nerve cells lined along the ciliary bands. During the transition to the doliolaria larvae, the nerve tracts rearranged together with the ciliary bands, but they were not segmented and remained continuous. The doliolaria larvae possessed nerves along the ciliary rings but strongly retained the features of auricularia larvae nerve pattern. The adult nervous system began to develop inside the doliolaria larvae before the larval nervous system disappears. None of the larval nervous system was observed to be incorporated into the adult nervous system with immunohistochemistry. Since S. japonicus are known to possess an ancestral mode of development for echinoderms, these results suggest that the larval nervous system and the adult nervous system were probably formed independently in the last common ancestor of echinoderms.

Neural architecture of the brachiolaria larva of the starfish, Asterina pectinifera

“…Staining of neurons in the lateral ganglia and other regions in the brachiolaria larva of A. pectinifera was almost eliminated by pretreatment of the diluted antibody with serotonin (25 g/mL, 4 hours at room temperature) but not with BSA, confirming the specificity of this antibody. These antibodies specifically recognize known and novel structures of the bipinnaria larval nervous system (Nakajima et al, 2004a) and the adult nervous system in A. pectinifera (Saha et al, 2006) as well as in other species of echinoderms and a hemichordate (Nakajima et al, 2004a,b;Burke et al, 2006a;Nakano et al, 2006). In the A. pectinifera brachiolaria larva, those antibodies stain only cells and cellular structures similar to typical echinodermal neurons and are used in immunohistochemistry.…”

“…Specimens were then rinsed in 0.1 M phosphate buffered saline containing 0.01% Triton X-100 (PBST) three times and then were briefly postfixed with acetone at Ϫ20°C. Immunostaining was carried out as described previously (Nakajima et al, 2004a,b;Nakano et al, 2006). For preserving spicules, 4% PFA in ASW buffered with 50 mM sodium borate (pH 9.5) was used as a fixative.…”

“…1E11 mAb recognizes the synaptotagmin B protein in the sea urchin that is a calcium-binding protein localized in synaptic vesicles (Burke et al, 2006a). Immunohistochemistry with the 1E11 mAb has revealed aspects of the neural organization in larval forms of sea urchins (Nakajima et al, 2004a;Burke et al, 2006a,b), sea cucumbers (Nakano et al, 2006;Bishops and Burke, 2007), hemichordates (Nakajima et al, 2004b) and the adult nervous system of asteroids (Saha et al, 2006). We have used similar methods to generate another mAb (1F9) that was used to describe sea cucumber neural development (Nakano et al, 2006).…”

The utilization of seagrass and macroalgae substrate for settlement of sandfish Holothuria scabra larvae

“…Umur larva doliolaria bervariasi tergantung pakan dan kondisi lingkungan. Larva memasuki fase doliolaria pada umur sepuluh hari sampai 15 hari (Rasolofonirina & Jangoux, 2005;Nakano et al, 2006;ZacariasSoto et al, 2013). Penelitian larva H. scabra mulai menempel setelah berumur dua minggu.…”

Induction of larval metamorphosis in the sea cucumber Apostichopus japonicus by neurotransmitters

“…The pentactula larvae could metamorphose to the juvenile stage without a chemical cue. The adult nervous system develops during the doliolaria stage [19]. The neurotransmitter may interact with the nervous system in the late doliolaria.…”