A fast Na+/Ca2+-based action potential in a marine diatom

Area of Science:

• Cellular Electrophysiology
• Marine Biology
• Evolutionary Biology

Background:

• Electrical impulses coordinate vital functions in animals, often relying on fast sodium (Na+)-based action potentials.
• These rapid action potentials are historically linked to multicellular animals, with cnidarians representing early forms.

Purpose of the Study:

• To investigate the presence and characteristics of action potentials in unicellular organisms.
• To explore the evolutionary origins of rapid electrical signaling mechanisms.

Main Methods:

• Utilized single-electrode current and voltage clamp techniques to analyze diatom action potentials.
• Examined the kinetic, ionic, and pharmacological properties of these electrical signals.

Main Results:

• Demonstrated that the marine diatom Odontella sinensis generates a fast Na+/Ca2+ based action potential.
• The action potential exhibits biophysical and pharmacological properties akin to those in invertebrate and vertebrate muscle cells.

Conclusions:

• This study provides the first evidence of voltage-activated Na+ channels and fast action potentials in a unicellular photosynthetic organism.
• Findings support the hypothesis that rapid signaling mechanisms originated in unicellular eukaryotes and were conserved in distantly related lineages.
• The functional role of these action potentials in diatoms may involve environmental sensing.