Mg2+-dependent electrical control of flagellar activity in Euglena

Area of Science:

• Cell Biology
• Biophysics
• Microbiology

Background:

• Euglena gracilis flagella exhibit complex responses to mechanical and chemical stimuli.
• Previous studies suggest calcium ions (Ca2+) play a role in flagellar detachment.

Purpose of the Study:

• To investigate the role of ions and electrical currents in controlling Euglena gracilis flagellar motility.
• To elucidate the mechanism underlying flagellar activity regulation.

Main Methods:

• Microelectrode impalement of Euglena gracilis cells in various ionic conditions.
• Application of external ATP and electrical current injection.
• High-speed cinemicrography for flagellar motion analysis.
• Use of gramicidin to alter membrane permeability.

Main Results:

• Flagellar ejection occurs in Ca2+-containing medium; activity is lost in Ca2+-free medium.
• External ATP sustains flagellar activity.
• Negative current injection stops flagellar activity, which recovers upon cessation.
• Gramicidin treatment reveals Mg2+-dependent flagellar activity regulated by electrical current.
• Mg2+ presence allows for multiple cycles of activity modulation.

Conclusions:

• Flagellar motility in Euglena gracilis is regulated by an electrically activated Mg2+ pump.
• Electrical currents modulate Mg2+ flux, thereby controlling flagellar activity.
• This mechanism offers a novel insight into the bioelectrical control of cellular appendages.