Cellular and intracellular pathways mediating the metamorphic stimulus in hydrozoan planulae
Gary Freeman1,2, Ellis B Ridgway1,3
1Friday Harbor Laboratories, University of Washington, 98250, Friday Harbor, WA, USA.
Summary
Calcium transients in hydrozoan planula cells trigger metamorphosis. These calcium signals, initiated by bacterial products or Cs+, propagate across cells, with full surface involvement necessary for metamorphosis induction. This indicates a crucial intercellular communication pathway.
Area of Science:
- Marine Biology
- Developmental Biology
- Cellular Physiology
Background:
- Metamorphosis in hydrozoans like Mitrocomella polydiademata is a critical developmental transition.
- Calcium ions play a recognized role in cellular signaling pathways.
Purpose of the Study:
- To investigate the role of calcium transients in the metamorphosis of Mitrocomella polydiademata planulae.
- To elucidate the spatial and temporal dynamics of calcium signaling during metamorphosis induction.
Main Methods:
- Utilizing a calcium-specific photoprotein in planula cells.
- Employing microscopy with image intensification and video recording to visualize calcium transients.
- Administering natural (bacterial) and artificial (Cs+) metamorphic stimuli.
- Using calcium channel blockers and protein kinase-C inhibitors to probe signaling pathways.
Main Results:
- Both natural and Cs+-induced metamorphosis involve large calcium transients in planula cells.
- Inhibition of calcium transients with blockers prevents metamorphosis.
- Calcium transients propagate across the planula surface, with full surface involvement being essential for induction.
- Phorbol ester-induced metamorphosis bypasses calcium transients, suggesting a different pathway.
- Calcium transients precede protein kinase-C activation in the metamorphic pathway.
Conclusions:
- Calcium transients are a necessary early step in bacterial and Cs+-induced metamorphosis of Mitrocomella planulae.
- The propagation of calcium transients likely serves as an intercellular communication system initiating metamorphosis.
- Metamorphosis can be induced via pathways independent of calcium transients, highlighting complex signaling networks.
Keywords:
Calcium transientsEpithelial conductionHydrozoaPlanula metamorphosisProtein kinase-C activationVoltage dependent calcium channelsMore Related Videos
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