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Phagocytes feed by forming food vacuoles. In this article the authors investigate the extent that exposure of non-nutritional food, such as India Ink, to Tetrahymena pyriformis affects the number of vacuole formation. These studies provide insight to how organisms budget their energy and metabolic processes during an energy shortage.

The surface of the unicellular eukaryote, Tetrahymena pyriformis, is covered with thousands of hair-like cilia. These cilia are very similar to cilia of the human olfactory and respiratory tracts making them model organisms for studying cilia function and pathology. The authors of this study investigated the effect of voltage on T. pyriformis galvanotaxis, the movement towards an electrical stimulus. They observed galvanotaxis towards the cathode at voltages over 4V which plateau, indicating opening of voltage gated-ion channels to trigger movement.

T. pyriformis can use phagocytosis to create vacuoles of carmine red, a dye which is made using crushed insects and is full of nutrients. Establishing a relationship between vacuole formation and duration of exposure to food can demonstrate how phagocytosis occurs in T. pyriformis. We hypothesized that if T. pyriformis was incubated in a carmine red solution, then more vacuoles would form over time in each cell.

In this study, the authors look into some of the implications of rising carbon dioxide levels by studying the effects of acidic pH on the ability of T. pyriformis to feed by quantifying phagosome formation and motility.