Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Paramecia need Newton for navigation

19.11.2014

While single-celled paramecia have the ability to respond to certain external stimuli, they appear not to use that sensory system for simple navigation, new research finds. The work suggests that the ability of paramecia to navigate around flat surfaces is entirely governed by Newton’s Third Law of Motion and not by active behavior. The finding, reported in Physical Review Letters, raises interesting evolutionary questions.

For such humble creatures, single-celled paramecia have remarkable sensory systems. Give them a sharp jab on the nose, they back up and swim away. Jab them in the behind, they speed up their swimming to escape. But according to new research, when paramecia encounter flat surfaces, they’re at the mercy of the laws of physics.


A counterintuitive phenomenon

The paramecium, normally a responsive swimmer, appears not to use its sensory network for navigation under certain circumstances. When in evolutionary history did active navigation become an advantage?

The findings, published in the journal Physical Review Letters, come from some surprising results in research performed in recent years by James Valles, professor and chair of physics at Brown University, and his students.

The group has been working to understand how paramecia react to changes in their buoyancy. The experiments are done by adding tiny magnetic particles to the water in which the creatures swim, and then applying a powerful magnet. When the water is pulled downward by the magnet, the paramecia become more buoyant and float more easily. Pull the water up, and the creatures become less buoyant.

The initial research, published a few years ago, showed that paramecia have a remarkable ability to sense the changes in their buoyancy and adjust their swimming behavior accordingly.

“We found that if we made them sink more by making them less buoyant, they would try to swim harder against that sinking,” Valles said. The effect was the same when the creatures were made more buoyant; they swam harder against the tendency to float.

But over the course of the experiments, a strange thing happened. When their buoyancy was increased, meaning the paramecia should float more easily, the creatures would eventually get stuck to the lower surface of their enclosure. When the researchers reversed the experiment, making the paramecia less buoyant, they got stuck at the top.

“It was so striking,” said Valles, who performed the latest experiments with graduate student Ilyong Jung and Karine Guevorkian of the Institut de Génétique et de Biologie Moléculaire et Cellulaire in France. “They looked like bats hanging from the top of a cave.”

To understand this counterintuitive phenomenon, Valles and his colleagues watched paramecia swim into surfaces both under normal buoyancy as well as with buoyancy altered. Under normal circumstances, the paramecia skitter along the surface briefly before turning and swimming away. But when buoyancy was increased, they failed to complete the turn, leaving them stuck at an angle against the lower surface.

The researchers determined that what they were seeing could be explained entirely by Newton’s Third Law of Motion. When the creatures push against a surface, the surface pushes back with equal force. Under normal circumstances that force is enough to cause the creatures to turn, enabling them to swim away. But when their buoyancy is increased, paramecia don’t hit the lower surface with as much force, which means the force applied back to them is also reduced.

“As they turn, that force of the wall acting on them gets smaller and smaller because they’re swimming at an angle against the surface,” Valles said. “It turns out that when buoyancy is altered, there’s an angle at which that force goes to zero before they complete the turn.”

And so there they stay, stuck at that angle against the surface.

The results are surprising, Valles said, because it implies that paramecia don’t respond to contact with surfaces by actively changing their swimming behavior — even though they have the ability to respond actively when poked and prodded.

“Paramecia are interesting to people because they’re like swimming nerve cells — they have this surprisingly complex force-sensing network,” Valles said. “But it appears as if it’s not necessary for them to use it for simple navigation.”

The findings raise some interesting evolutionary questions, Valles said.

“Fish and other higher organisms actively navigate,” he said. “But being passive apparently works just fine for paramecia; they’re in every pond you come across. The question that’s interesting to me is when in evolutionary history did a more active navigation become advantageous?”


Note to Editors:
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.

Kevin Stacey | EurekAlert!
Further information:
https://news.brown.edu/articles/2014/11/paramecia

More articles from Life Sciences:

nachricht Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>