Pioneering research has given a fascinating fresh insight into how animal nervous systems evolved from simple structures to become the complex network transmitting signals between different parts of the body.

The new study used simple multicellular organisms called Placozoa to reveal the beginnings of the nervous systems found in more complex animals.

The international research team, including Professor Gaspar Jekely from the University of Exeter's Living Systems Institute, found that Placozoa can coordinate their movement and body shape, in the absence of a nervous system, by signalling with small peptides between cells.

Professor Jekely believes that a peptidergic signalling system allows a very high complexity of behavioural organisation.

He said: "Each peptide can be used individually as a different signal, but the peptides could also be used sequentially or together in different combinations which allows for very high numbers of unique signals between cells. This explains how Placozoans can coordinate sophisticated behavioural sequences such as feeding."

Placozoans, the simplest of all animals, resemble a small, hairy disc about 1mm in size, with just three cell layers. Although they have no true nerve or muscle cells, they glide across surfaces in the ocean with apparent ease.

The new study explored how this multicellular animal with no nervous system can coordinate all the cells in its body to perform complex behaviour.

They found that Placozoan cells contain a variety of small peptides, made up of 4-20 amino acids that are secreted from one cell and detected by neighbouring cells as a means of communication.

Crucially, this echoes how more complex organisms use similar peptides, known as neuropeptides, for signalling within the nervous system.

Associate Professor Dirk Fasshauer, from the University of Lausanne, Switzerland and co-author of the study said: "These new findings show that outer appearances can be deceiving, because cells that look the same are actually signalling with different molecules and are very likely to have different functions."

Using synthetically constructed versions of the Placozoan signalling peptides, the researchers could tap into this hidden signalling system to understand the role of each peptide in coordinating movement and body shape.

The experiments revealed that the peptides changed Placozoan behaviour within seconds. Each peptide had a unique effect, which in some cases was very dramatic. The main behavioural changes caused by the peptides included crinkling, turning, flattening, and internal churning, a behaviour associated with feeding.

Dr. Frederique Varoqueaux, also from the University of Lausanne, added: "It might seem strange to use an animal with no neurons or synapses to study nervous system evolution, but although Placozoans are nerveless, you can still find within their cells the basic molecules needed for communication in complex nervous systems.

"So studying Placozoans can tell us more about the origins of neurons and how they became the body's control system."

The study is published in Current Biology on October 18 2018.

Research Report: "High cell diversity and complex peptidergic signalling underlie placozoan behaviour" is published in Current biology on Thursday, October 18, 2018.

Related Links
University of Exeter
Darwin Today At TerraDaily.com

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Scientists probe how dogs process words
Washington DC (UPI) Oct 15, 2018
Dogs respond to verbal cues, but the degree with which dogs understand and process words remains a mystery. To better understand how the canine brain comprehends different words, scientists imaged the brains of dogs responding to verbal cues. The analysis suggests dogs develop a basic neural image and definition of learned words. "Many dog owners think that their dogs know what some words mean, but there really isn't much scientific evidence to support that," Ashley Prichard, a doctoral ... read more