Network topology enables efficient response to environment inPhysarum polycephalum

Area of Science:

• Cellular Biology
• Evolutionary Biology
• Biophysics

Background:

• The unicellular slime mold *Physarum polycephalum* exhibits a unique network-shaped body plan, unlike most unicellular organisms.
• Network structures are prevalent in multicellular life, such as fungi, suggesting functional advantages.

Purpose of the Study:

• To investigate the survival advantage of network topology in *Physarum polycephalum* when facing environmental challenges.
• To determine how network structure influences the organism's avoidance response to adverse stimuli like blue light.

Main Methods:

• Stimulating both I-shaped (elongated) and Y-shaped (networked) *Physarum polycephalum* specimens with blue light.
• Quantifying the evacuation process and migration velocity of light-exposed body parts.
• Analyzing contraction amplitude to assess energetic efficiency during retraction.

Main Results:

• Y-shaped specimens retracted from light exposure comparably to, or slightly faster than, I-shaped specimens.
• The avoidance response in Y-shaped organisms showed a negligible increase in migration velocity and localized contraction.
• These findings indicate a more energetically efficient avoidance reaction in the networked Y-shaped slime mold.

Conclusions:

• Network topology provides a significant advantage for organisms navigating adverse environments.
• The efficient avoidance strategy of networked slime molds may offer insights into the unicellular-to-multicellular transition.