Gravitational Biology

How does a paramecium know what's up and what's down?

 Slipper animal (<i>Paramecium caudatum</i>)
zum Bild Slipper animal (Paramecium caudatum)

Of course, most animals know which direction is up and which is down – otherwise they would not be able to navigate their surroundings. Orientation helps them to find food and avoid danger. But is this also true of single cell organisms? Do paramecia (or “slipper animals”) in a puddle react to the earth’s gravitational pull? Or do they use other stimuli such as light or temperature? And are our observations the results of the laws of physics or are other mechanisms needed to explain them?

We will establish several hypotheses and test them by carrying out experiments on the swimming behaviour of paramecia. Using a video camera and a special computer programme, we will record the directions in and the velocities with which paramecia swim.

The interesting question is: Can we transfer the mechanism that paramecia use to orientate themselves onto a specialised human cell? Our findings might even be important within aerospace medicine.

 An astronaut on a space walk
zum Bild An astronaut on a space walk

What do frogs, fish, mice and astronauts have in common?

On Earth, gravity is the only reliable stimulus. It is always there, always has the same directionality and hardly changes at all. If single cell organisms, like paramecia, use gravity as their means of orientation, how is this possible, given that they have no sensory organs, no nervous system and no brain? Would it then be possible for our cells to have inherited the ability to perceive gravity? And what would happen to these cells, if they were exposed to the exceptional circumstances of weightlessness for a prolonged period of time?

 Observing slipper animals under a microscope
zum Bild Observing slipper animals under a microscope

Because we are pursuing answers to these questions in a variety of ways, there are some frogs, mice and fish that have flown on a Space Shuttle and have seen the inside of the International Space Station (ISS). Astronauts are among those interested in the insights to be gained from biological research, as we hope one day to be able to solve some of the long-term problems of living in weightlessness.

Further information: How we can learn from our 1.6 billion-year-old ancestors

Dr. rer.-nat. Richard Bräucker
German Aerospace Center

Tel: +49 (0)2203 601-3093

Fax: +49 (0)2203 601-13093

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