Sensory flask cells in sponge larvae regulate metamorphosis via calcium signaling

Nakanishi, Nagayasu, Stoupin, Daniel, Degnan, Sandie M. and Degnan, Bernard M. (2015). Sensory flask cells in sponge larvae regulate metamorphosis via calcium signaling. In: Annual meeting of the Society for Integrative and Comparative Biology, West Palm Beach, Florida, United States, (1018-1027). 3-7 January 2015. doi:10.1093/icb/icv014


Author Nakanishi, Nagayasu
Stoupin, Daniel
Degnan, Sandie M.
Degnan, Bernard M.
Title of paper Sensory flask cells in sponge larvae regulate metamorphosis via calcium signaling
Conference name Annual meeting of the Society for Integrative and Comparative Biology
Conference location West Palm Beach, Florida, United States
Conference dates 3-7 January 2015
Journal name Integrative and Comparative Biology   Check publisher's open access policy
Place of Publication Oxford, United Kingdom
Publisher Oxford University Press
Publication Year 2015
Sub-type Fully published paper
DOI 10.1093/icb/icv014
Open Access Status Not Open Access
ISSN 1557-7023
1540-7063
Volume 55
Issue 6
Start page 1018
End page 1027
Total pages 10
Language eng
Formatted Abstract/Summary
The Porifera (sponges) is one of the earliest phyletic lineages to branch off the metazoan tree. Although the body-plan of sponges is among the simplest in the animal kingdom and sponges lack nervous systems that communicate environmental signals to other cells, their larvae have sensory systems that generate coordinated responses to environmental cues. In eumetazoans (Cnidaria and Bilateria), the nervous systems of larvae often regulate metamorphosis through Ca2+-dependent signal transduction. In sponges, neither the identity of the receptor system that detects an inductive environmental cue (hereafter “metamorphic cues”) nor the signaling system that mediates settlement and metamorphosis are known. Using a combination of behavioral assays and surgical manipulations, we show here that specialized epithelial cells—referred to as flask cells—enriched in the anterior third of the Amphimedon queenslandica larva are most likely to be the sensory cells that detect the metamorphic cues. Surgical removal of the region enriched in flask cells in a larva inhibits the initiation of metamorphosis. The flask cell has an apical sensory apparatus with a cilium surrounded by an apical F-actin-rich protrusion, and numerous vesicles, hallmarks of eumetazoan sensory-neurosecretory cells. We demonstrate that these flask cells respond to metamorphic cues by elevating intracellular Ca2+ levels, and that this elevation is necessary for the initiation of metamorphosis. Taken together, these analyses suggest that sponge larvae have sensory-secretory epithelial cells capable of converting exogenous cues into internal signals via Ca2+-mediated signaling, which is necessary for the initiation of metamorphosis. Similarities in the morphology, physiology, and function of the sensory flask cells in sponge larvae with the sensory/neurosecretory cells in eumetazoan larvae suggest this sensory system predates the divergence of Porifera and Eumetazoa.
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Document type: Conference Paper
Collections: Official 2016 Collection
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