Patch-clamp recordings in isolated sponge cells (Axinella polypoides)

Area of Science:

• Marine Biology
• Cellular Electrophysiology
• Evolutionary Biology

Background:

• Sponges are the earliest metazoans, with specialized cells but lacking true tissues or organs.
• Evidence suggests electrical signaling occurs in sponge cells, but ionic channel characterization is limited.
• Sponge cell membranes present challenges for electrophysiology due to glycocalyx and fatty acid composition.

Purpose of the Study:

• To detail a methodology for overcoming patch-clamp difficulties in sponge cells.
• To enable electrophysiological measurements on the membranes of sponge cells.
• To demonstrate the characterization of ionic conductances in sponge cells.

Main Methods:

• Isolation of cells from the Mediterranean Demospongia Axinella polypoides.
• Application of the patch-clamp technique with modifications using trivalent cations in the extracellular solution.
• Detailed description of the experimental setup and procedures for achieving stable recordings.

Main Results:

• Successfully overcame low tight seal percentages (initially 3%) previously obtained.
• Demonstrated the feasibility of performing electrophysiological measurements on sponge cell membranes.
• Identified and characterized a potassium-selective conductance as a proof of concept.

Conclusions:

• The developed methodology enables robust electrophysiological studies in sponge cells.
• This approach opens new avenues for investigating electrical signaling in basal metazoans.
• The technique may be applicable to other cell types with similar membrane complexities.