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Development of the nervous system in the brittle star Amphipholis kochii

Development of the nervous system in the brittle star Amphipholis kochii,10.1007/s00427-007-0196-6,Development Genes and Evolution,Taiji Hirokawa,Miék

Development of the nervous system in the brittle star Amphipholis kochii   (Citations: 6)
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There are several studies of neural development in various echinoderms, but few on ophiuroids, which develop indirectly via the production of pluteus larvae, as do echinoids. To determine the extent of similarity of neuroanatomy and neural development in the ophiuroids with other echinoderm larvae, we investigated the development of the nervous system in the brittle star Amphipholis kochii (Echinodermata: Ophiuroidea) by immunohistochemistry. Immunoreactive cells first appeared bilaterally in the animal pole at the late gastrula stage, and there was little migration of the neural precursors during A. kochii ontogeny, as is also the case in echinoids and holothuroids. On the other hand, neural specification in the presumptive ciliary band near the base of the arms does occur in ophiuroid larvae and is a feature they share with echinoids and ophiuroids. The ophiopluteus larval nervous system is similar to that of auricularia larvae on the whole, including the lack of a fine network of neurites in the epidermis and the presence of neural connections across the oral epidermis. Ophioplutei possess a pair of bilateral apical organs that differ from those of echinoid echinoplutei in terms of relative position. They also possess coiled cilia, which may possess a sensory function, but in the same location as the serotonergic apical ganglia. These coiled cilia are thought to be a derived structure in pluteus-like larvae. Our results suggest that the neural specification in the animal plate in ophiuroids, holothuroids, and echinoids is a plesiomorphic feature of the Ambulacraria, whereas neural specification at the base of the larval arms may be a more derived state restricted to pluteus-like larvae.
Journal: Development Genes and Evolution - DEV GENES EVOL , vol. 218, no. 1, pp. 15-21, 2008
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    • ...Reports from asteroids, ophiuroids, and holothurians showed that none of the larval nervous system is incorporated into the adult nervous system (Byrne and Cisternas2002; Dupont et al. 2009; Hirokawa et al. 2008; Mashanov et al. 2007; Nakano et al. 2006; Nezlin et al. 1991)...
    • ...It has been shown to specifically recognize the nervous system in echinoderms (Bishop and Burke 2007; Dupont et al. 2009; Hirokawa et al. 2008; Nakajima et al. 2004b; Nakano et al. 2006; Nakajima, unpublished)...
    • ...Neural precursors showing preneuronal expression of serotonin have been reported to appear bilaterally at the animal pole of the gastrulae during ophiuroid, holothurian, and echinoid development (Bishop and Burke 2007; Dupont et al. 2009; Hirokawa et al. 2008; Nakajima et al. 2004b; Nakano et al. 2006)...
    • ...3 and 4). Ciliary band nerve tracts immunoreactive to 1E11 are present in hemichordate tornaria larvae (Nakajima et al. 2004a; Miyamoto et al., unpublished) as well as various echinoderm larvae (Bishop and Burke 2007; Burke et al. 2006; Dupont et al. 2009; Hirokawa et al. 2008; Nakajima et al. 2004b; Nakano et al. 2006) and are regarded as a plesiomorphic feature of ambulacrarian larvae...
    • ...It has been reported in the ophiuroid Amphipholis kochii that some neurons do not react with the synaptotagmin antibody (Hirokawa et al. 2008), and this is probably also the case in crinoids...
    • ...The same has been previously suggested in asteroids (Byrne and Cisternas 2002; Nezlin et al. 1991), ophiuroids (Dupont et al. 2009; Hirokawa et al. 2008), and holothuroids (Mashanov et al. 2007; Nakano et al. 2006), but the observations on the feather star O. japonicus here are the first to show that the larval nervous system does not participate in the formation of the aboral nerve center of crinoids...

    Hiroaki Nakanoet al. Nervous system development of two crinoid species, the sea lily Metacr...

    • ...The data for ophiuroids is fragmentary; there are descriptions of some larval stages using antibodies to subsets of neurons (Cisternas and Byrne 2003), and recently Hirokawa et al. 2008 described neural development in Amphipholis kochii with anti-synaptotagmin...
    • ...The ontogenetic data, now from two species (Hirokawa et al. 2008), indicates that the serotonergic cells of ophiuroids, despite their dorsolateral position, correspond to the apical organs of other metazoans...
    • ...It is often stated that there are no connections between the two systems in stages in which they co-exist (Beer et al. 2001 ;N akano et al.2006; Hirokawa et al. 2008)...
    • ...The data on neural development in ophiuroids together with the data on hemichordate neural development (Nakajima et al. 2004b; Nezlin and Yushin 2004; Nielsen and Hay-Schmidt 2007) and neural development in the other classes of echinoderms (Nakajima et al. 2004a; Nakano et al. 2006; Bishop and Burke 2007; Hirokawa et al. 2008) can be plotted on a cladogram based on current phylogenies (Fig. 5). In this view, the pleisiomorphic features of ...

    Sam Dupontet al. Neural development of the brittlestar Amphiura filiformis

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