Neurogenesis in directly and indirectly developing enteropneusts: of nets and cords

Sabrina Kaul-Strehlow, Makoto Urata, Takuya Minokawa, Thomas Stach, Andreas Wanninger

研究成果: Article査読

16 被引用数 (Scopus)

抄録

Concerning the evolution of deuterostomes, enteropneusts (acorn worms) occupy a pivotal role as they share some characteristics with chordates (e.g., tunicates and vertebrates) but are also closely related to echinoderms (e.g., sea urchin). The nervous system in particular can be a highly informative organ system for evolutionary inferences, and advances in fluorescent microscopy have revealed overwhelming data sets on neurogenesis in various clades. However, immunocytochemical descriptions of neurogenesis of juvenile enteropneusts are particularly scarce, impeding the reconstruction of nervous system evolution in this group. We followed morphogenesis of the nervous system in two enteropneust species, one with direct (Saccoglossus kowalevskii) and the other with indirect development (Balanoglossus misakiensis), using an antibody against serotonin and electron microscopy. We found that all serotonin-like immunoreactive (LIR) neurons in both species are bipolar ciliary neurons that are intercalated between other epidermal cells. Unlike the tornaria larva of B. misakiensis, the embryonic nervous system of S. kowalevskii lacks serotonin-LIR neurons in the apical region as well as an opisthotroch neurite ring. Comparative analysis of both species shows that the projections of the serotonin-LIR somata initially form a basiepidermal plexus throughout the body that disappears within the trunk region soon after settlement before the concentrated dorsal and ventral neurite bundles emerge. Our data reveal a highly conserved mode of neurogenesis in enteropneusts that is independent of the developing mode and is inferred to be a common feature for Enteropneusta. Moreover, all detected serotonin-LIR neurons are presumably receptor cells, and the absence of serotonin-LIR interneurons from the enteropneust nervous system, which are otherwise common in various bilaterian central nervous systems, is interpreted as a loss that might have occurred already in the last common ancestor of Ambulacraria.

本文言語English
ページ(範囲)405-422
ページ数18
ジャーナルOrganisms Diversity and Evolution
15
2
DOI
出版ステータスPublished - 2015 6 6

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

フィンガープリント 「Neurogenesis in directly and indirectly developing enteropneusts: of nets and cords」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル