Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Proton-powered pooping

11.01.2008
Muscles usually contract when a neurotransmitter molecule is released from nerve cells onto muscle cells. But University of Utah scientists discovered that bare subatomic protons can act like larger, more complex neurotransmitters, making gut muscles contract in tiny round worms so the worms can poop.

“There are relatively few molecules that serve as neurotransmitters to trigger electrical changes in cells. Protons are the only new members of this group in nearly 20 years,” says biology Professor Erik Jorgensen, scientific director of the Brain Institute at the University of Utah and senior author of the study in the Jan. 11 issue of the journal Cell.

While conventional neurotransmitters such as serotonin, dopamine and GABA are molecules made of many atoms, the new study revealed a surprise: Protons – which are single hydrogen atoms stripped of their electrons – are pumped out of a round worm’s gut by one kind of protein and then bind to receptor proteins on neighboring muscles, making the muscles contract so the worm defecates.

Not only did the researchers show protons can act like neurotransmitters, they identified the genes and proteins involved in the process in round worms, which are about 1 millimeter (a 25th of an inch) long and also are known as nematodes.

Previous research indicated the brains of humans and mice also have proton pumps and receptors to move protons between cells. The new study raises the possibility those protons may be transmitting nerve signals in the brain, says Jorgensen and study co-author Wayne Davis, a research assistant professor of biology.

“This is the first time we have found protons acting as transmitters,” Davis says. “It could be that these processes occur in humans. There are proton pumps present in intestinal cells and in the brain of humans and mice. Some of the pumps are thought to make acid for the gut to digest food. But why are proton pumps in the brain"”

Jorgensen adds: “Mice lacking the proton receptor cannot learn. It may be that the proton pump and receptor are required for learning,” and thus protons may act like neurotransmitters in the brain.

Utah graduate student Asim Beg (now at Columbia University) conducted the study with Jorgensen, Davis, graduate student Paola Nix and postdoctoral researcher Glen Ernstrom.

A Discovery from Constipated Worms

Atoms are made of nuclei that contain positively charged protons and uncharged neutrons, orbited by negatively charged electrons. So protons are among the smallest components of matter.

Previously recognized neurotransmitters such as serotonin (known for its role in preventing depression) and dopamine (involved in addiction to cocaine and other drugs) are more than 100 times larger than protons. That makes protons “the world’s smallest transmitter,” says Jorgensen, also a Howard Hughes Medical Institute investigator.

Acids burn because they contain high concentrations of protons, which already were known to help the stomach digest food.

The new study shows that at least in some circumstances, protons also may be used by cells to communicate. “Normally you think of proton concentration increasing to digest food,” Davis says. “Now we see the cell is using these protons to communicate. The protons are acting like a word in a language that cells use to talk to each other.”

When the study began, nobody thought a new transmitter would be identified. Instead, the researchers were trying to understand how worms poop. Why" “Eating, moving, having sex and pooping are common things that all animals do,” says Davis.

Nematodes, or Caenorhabditis elegans, have about 1,000 cells and are simple animals studied by researchers worldwide. Nematodes have many of the same tissues – nerves, muscle and intestine – that are found in humans, and most of the same genes, making the worm a model for studying human biology.

Defecation in round worms is surprisingly complex. The animal has muscle contractions every 50 seconds that result in expulsion of intestinal contents. The 50-second cycle is an example of a biological clock, like those that regulate wake-sleep cycles and many other behaviors in animals.

“We were interested in teasing apart the components required for [defecation] clock function,” says Nix. “To do that we searched for mutations that affected the clock.”

By exposing worms to chemicals that altered their DNA, the researchers found mutant worms that couldn’t defecate or had trouble doing so. “The worms are constantly eating, so if they don’t poop regularly, they become very constipated,” says Nix.

In the round worm’s tail, muscles surround the tube-shaped intestine, and there is a fluid-filled space between the intestine and the surrounding muscles. The muscles contract to help the worm defecate. The researchers identified two different gene mutations that prevented such contractions.

Proteins and Protons Propel Pooping Process

One gene, named pbo-4 (for posterior body contraction), produces a protein that pumps protons out of the intestine, acting “like a revolving door where sodium is allowed in [the gut] while protons go out [of the gut] into the fluid-filled space that is very close to the surrounding muscle,” says Davis.

The second gene, pbo-5, makes a receptor protein on the muscles that surround the gut. After the protons are released from the intestine, they bind to the receptor protein.

“The receptor acts like an ear that allows the muscle to hear that protons are present,” says Beg. The receptor opens when the proton binds to it, forming a hole in the muscle cell that allows large numbers of ions like sodium to flow in. The ions make the muscle contract.

The researchers knew protons were being released from the gut because they could see their effects through a microscope.

They bred worms with a green fluorescent protein that loses it color when many protons are present. The adult worms had the green protein in the fluid-filled space between the intestine and the surrounding muscle – a space that Ernstrom says “is approximately 1,000 times smaller than the width of a hair.”

The scientists were able to show protons were pumped from the intestinal wall and to the surrounding muscle because, under a microscope, the fluid-filled space became less green. In mutant worms lacking the proton pump, the green remained unchanged, showing that protons were not released from the gut into the space.

In the next experiment, the researchers added protons to the fluid-filled space between the intestine and surrounding muscle in the mutants lacking the proton pump. The added protons made the muscle contract. That indicated protons indeed were acting like a neurotransmitter to carry the signal for contraction from the intestine to the surrounding muscle.

“To prove that it is the protons triggering the contraction, we want to supply the protons ourselves,” says Davis. “A fine needle filled with protons was used to inject protons in the space between the muscle and gut. We can bypass the gut and fool the muscle into thinking the gut is releasing protons, and the muscle contracts.”

Lee Siegel | EurekAlert!
Further information:
http://www.utah.edu
http://www.unews.utah.edu

Further reports about: Jorgensen Neurotransmitter contraction fluid-filled intestine proton pump pump receptor

More articles from Life Sciences:

nachricht Turning carbon dioxide into liquid fuel
06.08.2020 | DOE/Argonne National Laboratory

nachricht Tellurium makes the difference
06.08.2020 | Friedrich-Schiller-Universität Jena

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>