Feeding by Actinophrys sol (Protista, Heliozoa): 1 light microscopy

Area of Science:

• Cell Biology
• Protistology
• Microbiology

Background:

• Actinophrys sol is a heliozoan protist known for its predatory behavior.
• Understanding feeding mechanisms in unicellular organisms provides insights into fundamental biological processes.

Purpose of the Study:

• To investigate and detail the feeding behavior of Actinophrys sol.
• To elucidate the cellular processes involved in prey capture, digestion, and waste elimination.

Main Methods:

• Observation of Actinophrys sol feeding on the ciliate Colpidium colpoda.
• Microscopic analysis of cellular changes during feeding and digestion.
• Investigation of the role of extrusomes in the feeding process.

Main Results:

• Prey capture occurs via adhesion to heliozoan arms, followed by enclosure with a funnel-shaped pseudopodium.
• Ingested prey (Colpidium colpoda) are lysed, and food vacuole contents coagulate and condense within 4 hours.
• Extrusomes are depleted during feeding, suggesting their involvement in prey capture and food vacuole membrane formation.

Conclusions:

• Actinophrys sol exhibits a complex feeding strategy involving cellular fusion, specialized pseudopodia, and efficient digestion.
• The process highlights the dynamic nature of protist cell morphology and function during nutrient acquisition.
• Extrusomes are critical components in the feeding apparatus of Actinophrys sol.