Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

From worm muscle to spinal discs - An evolutionary surprise

12.09.2014

Thoughts of the family tree may not be uppermost in the mind of a person suffering from a slipped disc, but those spinal discs provide a window into our evolutionary past. They are remnants of the first vertebrate skeleton, whose origins now appear to be older than had been assumed.

Scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have found that, unexpectedly, this skeleton most likely evolved from a muscle. The study, carried out in collaboration with researchers at the Howard Hughes Medical Institute in Janelia Farm, USA, is published today in Science.


The marine worm Platynereis has a muscle (red) which develops in the same place and has the same genetic signature as the notochord (blue) that develops into our spinal discs. Credit: Kalliopi Monoyios

Humans are part of a group of animals called chordates, whose defining feature is a rod of cartilage that runs lengthwise along the middle of their body, under their spinal chord. This structure, called the notochord, was the first vertebrate skeleton. 

It is present in human embryos, and is replaced with the backbone as we develop, with the cartilage reduced to those tell-tale discs. Since starfish, sea urchins and related animals have no such structure, scientists assumed the notochord had emerged in a relatively recent ancestor, after our branch of the evolutionary tree split away from the ‘starfish branch’.

“People simply haven’t been looking beyond our direct relatives, but that means you could be fooled, if the structure appeared earlier and that single group lost it,” says Detlev Arendt from EMBL, who led the study. “And in fact, when we looked at a broader range of animals, this is what we found.”

Antonella Lauri and Thibaut Brunet, both in Arendt’s lab, identified the genetic signature of the notochord – the combination of genes that have to be turned on for a healthy notochord to form. When they found that the larva of the marine worm Platynereis dumerilii has a group of cells with that same genetic signature, the scientists teamed up with Philipp Keller’s group at Janelia Farm to use state-of-the-art microscopy to follow those cells as the larva developed.

They found that the cells form a muscle that runs along the animal’s midline, precisely where the notochord would be if the worm were a chordate. The researchers named this muscle the axochord, as it runs along the animal’s axis. A combination of experimental work and combing through the scientific literature revealed that most of the animal groups that sit between Platynereis and chordates on the evolutionary tree also have a similar, muscle-based structure in the same position.

The scientists reason that such a structure probably first emerged in an ancient ancestor, before all these different animal groups branched out on their separate evolutionary paths. Such a scenario would also explain why the lancelet amphioxus, a ‘primitive’ chordate, has a notochord with both cartilage and muscle. Rather than having acquired the muscle independently, amphioxus could be a living record of the transition from muscle-based midline to cartilaginous notochord.

The shift from muscle to cartilage could have come about because a stiffened central rod would make swimming more efficient, the scientists postulate. 

Published online in Science on 12 September 2014. DOI: 10.1126/science.1253396.
For images, video and more information please visit: www.embl.org/press/2014/140911_Heidelberg

Policy regarding use

EMBL press and picture releases including photographs, graphics and videos are copyrighted by EMBL. They may be freely reprinted and distributed for non-commercial use via print, broadcast and electronic media, provided that proper attribution to authors, photographers and designers is made.

Sonia Furtado Neves | EMBL Research News

Further reports about: Biology EMBL Farm Laboratory Molecular amphioxus ancestor animals branch cartilage larva spinal starfish

More articles from Life Sciences:

nachricht Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden

nachricht The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>