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Single-Celled Organisms Forced To Play Life-Or-Death Pac-Man

Microbiologists at the University College of Southeast Norway have created a microscopic version of Pac-Man, played by single-celled organisms called euglena. The euglena must navigate a maze-like environment similar to a level of Pac-Man while being chased by ‘ghosts’ in the form of microscopic multicellular organisms which prey upon euglena.

This minuscule Pac-Man is part of an experiment to study how unicellular organisms behave and react to stimuli while under duress. Euglena, the Pac-Men of this experiment, are tiny one-celled creatures that typically inhabit bodies of fresh water.

Euglena, unicellular organisms commonly used in scientific experiments

Euglena, unicellular organisms commonly used in scientific experiments

Euglena are a common subject of scientific experimentation due to their abundance and resiliency, and have even been eyed as a potential future food source for the ever-expanding human population.

The Pac-Man enemies, or ‘ghosts,’ are represented by rotifers, a group of multicellular organisms which feed upon organic matter and are widely distributed worldwide.

Rotifers are found worldwide and are an important part of the health of bodies of water

Rotifers are found worldwide and can help clean bodies of water

The ‘decision-making’ of one-celled organisms such as euglena is based solely on responses to changes in the organisms’ chemical environments. By enticing the euglena with certain chemicals within the maze, the team of Norwegian scientists was able to control the organism’s chemotaxis, or responses to chemical stimuli.

The Pac-Man-style maze was created out of silicon nanostructures and laced with caffeine and Cyclic adenosine monophosphate (cAMP), a cellular messenger molecule created by the ATP cycle.

Euglena traversing the maze with rotifer 'ghosts' hot on their heels

Pac-Man euglena traversing the maze with rotifer ‘ghosts’ hot on their heels

The euglena are stimulated into traversing the maze by their innate chemical attraction towards the caffeine and cAMP. Lead researcher Erik Andrew Johannsen states that the Pac-Man-maze-like environment simulates the euglena’s natural habitat, which allows scientists to understand the organism’s natural behavior:

By introducing a three-dimensional maze in the Petri dish, we force them to interact with the environment and thus a more natural behavior, as expected, will allow researchers more valuable data [translated from Norwegian]

This experiment is similar to the 2014 Dicty World Races, a series of experiments designed to find the “world’s fastest and smartest Dicty cells.” The Pac-Man experiment and Dicty races are part of larger attempts to make scientific experimentation more accessible to the general public in hopes of increasing scientific awareness (and funding, no doubt).