Eukaryotic Chemotaxis under Periodic Stimulation Shows Temporal Gradient Dependence.

Area of Science:

• Cellular biology
• Biophysics
• Developmental biology

Background:

• Social amoeba Dictyostelium discoideum use cyclic adenosine monophosphate (cAMP) as a chemical messenger.
• Nutrient starvation triggers cAMP synthesis and secretion, leading to cell aggregation.
• Periodic waves of cAMP guide cell movement through chemotaxis.

Purpose of the Study:

• To investigate the chemotactic response of individual Dictyostelium discoideum cells to repeated cAMP wave exposure.
• To understand how cellular memory influences chemotaxis in response to periodic signals.
• To model the underlying mechanisms of enhanced chemotactic ability.

Main Methods:

• Utilized a microfluidic device to generate controlled waves of cAMP.
• Observed and analyzed the chemotactic response of individual cells to varying wave frequencies.
• Developed and applied a computational model (local excitation-global inhibition) to interpret experimental data.

Main Results:

• Cellular chemotactic ability increased with repeated exposure to fast-moving cAMP waves (short period).
• This enhancement in chemotaxis was not significant for slow-moving waves (large period).
• Experimental data aligned with a model incorporating a slow-rising and decaying component activated by the temporal cAMP gradient.

Conclusions:

• Dictyostelium discoideum cells exhibit a form of memory that enhances chemotaxis in response to periodic cAMP signals.
• This enhanced chemotaxis is beneficial for efficient aggregation towards the signaling center.
• The findings provide insights into cellular adaptation and collective behavior in response to environmental cues.