Comb Jellies and parallel neural system development

Looks like they took an alternate route than others...

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Comb Jellies and parallel neural system development

#1  Postby kennyc » May 21, 2014 10:35 pm

Very interesting findings....apparently these creatures use different genes to form their nervous system and brain. A case of parallel evolution, both resulting in brains, but in a very different way.

'Aliens of sea' offer new insight into evolution

March 30, 2014: This photo shows a sea salp and some mysterious creatures named comb jellies, caught by University of Florida neurobiologist Leonid Moroz while diving in the Gulf Stream off the coast of Florida.AP
WASHINGTON – Exotic sea creatures called comb jellies may reshape how scientists view early evolution -- as their genes suggest nature created more than one way to make a nervous system.

These beautiful but little-known translucent animals often are called "aliens of the sea," for good reason. Somehow, they rapidly regenerate lost body parts. Some even can regrow a very rudimentary brain.

Now in an in-depth look at the genes of 10 comb jelly species, researchers report that these mysterious creatures evolved a unique nervous system in a completely different way than the rest of the animal kingdom.

In other words, the nervous system evolved more than once, a finding published Wednesday by the journal Nature that challenges long-standing theories about animal development.

"This paper proves, on a genomic basis, they're truly aliens," said University of Florida neurobiologist Leonid Moroz, whose team spent seven years unraveling the genetics behind comb jellies' neural programming.

But the findings aren't just about evolutionary history. Comb jellies build a nervous system essentially using their own biological language, Moroz explained. That points to new ways to investigate brain diseases such as Alzheimer's or Parkinson's -- maybe even, one day, the ability to engineer new neurons, Moroz said.

They "open to us completely unexpected windows," he said.

Moroz is exploring some of those windows using a unique floating laboratory that allows sophisticated genomic sequencing at sea. In a test run off the coast of Florida this spring, The Associated Press documented how his team is studying which genes switch on and off as iridescent comb jellies regenerate from injury.

All animals evolved from a single ancestor. Scientists want to determine which branches broke off first, and how the earliest animals gradually changed to become more complex. The general theory: The oldest animals were the simplest, and once neural systems emerged, they evolved in a straightforward path from primitive nerve nets up to complex human brains.
....


http://news.nationalgeographic.com/news ... e-science/

From Nature: http://www.nature.com/news/jelly-genome-mystery-1.15264
Last edited by kennyc on May 22, 2014 1:24 am, edited 1 time in total.
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Re: Comb Jellies and parallel neural system development

#2  Postby Munchies » May 21, 2014 10:46 pm

Nice example of convergent evolution
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Re: Comb Jellies and parallel neural system development

#3  Postby Teuton » May 21, 2014 10:56 pm

kennyc wrote:Very interesting findings....apparently these creatures use different genes to form their nervous system and brain. A case of parallel evolution, both resulting in brains, but in a very different way.


Comb jellies have no brain or central nervous system.
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Re: Comb Jellies and parallel neural system development

#4  Postby kennyc » May 21, 2014 10:57 pm

Teuton wrote:
kennyc wrote:Very interesting findings....apparently these creatures use different genes to form their nervous system and brain. A case of parallel evolution, both resulting in brains, but in a very different way.


Comb jellies have no brain or central nervous system.


Tell that to the biologists studying them. :lol:
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Re: Comb Jellies and parallel neural system development

#5  Postby Teuton » May 21, 2014 11:24 pm

kennyc wrote:
Teuton wrote:
Comb jellies have no brain or central nervous system.

Tell that to the biologists studying them. :lol:


I don't have to, because they know it already.

"Nervous systems are found in almost all multicellular animals, but vary greatly in complexity. The only multicellular animals that have no nervous system at all are sponges and microscopic bloblike organisms called placozoans and mesozoans. The nervous systems of ctenophores (comb jellies) and cnidarians (e.g., anemones, hydras, corals and jellyfishes) consist of a diffuse nerve net. All other types of animals, with the exception of echinoderms and a few types of worms, have a nervous system containing a brain, a central cord (or two cords running in parallel), and nerves radiating from the brain and central cord.

Jellyfish, comb jellies, and related animals have diffuse nerve nets rather than a central nervous system. In most jellyfish the nerve net is spread more or less evenly across the body; in comb jellies it is concentrated near the mouth. The nerve nets consist of sensory neurons, which pick up chemical, tactile, and visual signals; motor neurons, which can activate contractions of the body wall; and intermediate neurons, which detect patterns of activity in the sensory neurons and, in response, send signals to groups of motor neurons. In some cases groups of intermediate neurons are clustered into discrete ganglia (Ruppert et al., 2004).
The development of the nervous system in radiata is relatively unstructured. Unlike bilaterians, radiata only have two primordial cell layers, the endoderm and ectoderm. Neurons are generated from a special set of ectodermal precursor cells, which also serve as precursors for every other ectodermal cell type (Sanes et al., 2006)."


http://www.scholarpedia.org/article/Nervous_system
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Re: Comb Jellies and parallel neural system development

#6  Postby Teuton » May 21, 2014 11:41 pm

"The members of the phylum Ctenophora exhibit the following general characteristics:

* They lack a brain but are equipped with a subepidermal plexus (bundle) of nerves concentrated under each comb plate."


(Springer, Joseph T., and Dennis Holley. An Introduction to Zoology: Investigating the Animal World. Burlington, MA: Jones&Bartlett, 2013. p. 156)

Note that to say that comb jellies do not have a brain or central nervous system is not to say they do not have a nervous system!
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Re: Comb Jellies and parallel neural system development

#7  Postby kennyc » May 21, 2014 11:58 pm

Like some posters.
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Re: Comb Jellies and parallel neural system development

#8  Postby kennyc » May 22, 2014 1:31 am

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Re: Comb Jellies and parallel neural system development

#9  Postby Teuton » May 22, 2014 3:56 pm

"'Some ctenophores can regenerate an elementary brain — also known as the aboral organ or gravity sensor — in 3 ½ days,' Moroz said. 'In one of my experiments, one lobate ctenophore  — Bolinopsis –  regenerated its brain four times.' In the Nature article,…"

http://news.ufl.edu/2014/05/21/origins-of-neurons/

In the scientific paper published in Nature, Moroz expresses himself more precisely:

"The aboral organ has the greatest diversity and highest expression levels of 12 gap junction proteins, suggesting unmatched expansion of electrical signalling in this complex integrative organ—an analogue of an elementary brain in ctenophores."

http://www.nature.com/nature/journal/va ... 13400.html

Image

"Ctenophores have no brain or central nervous system, but instead have a nerve net (rather like a cobweb) that forms a ring round the mouth and is densest near structures such as the comb rows, pharynx, tentacles (if present) and the sensory complex furthest from the mouth.
The largest single sensory feature is the aboral organ (at the opposite end from the mouth). Its main component is a statocyst, a balance sensor consisting of a statolith, a solid particle supported on four bundles of cilia, called "balancers", that sense its orientation. The statocyst is protected by a transparent dome made of long, immobile cilia. A ctenophore does not automatically try to keep the statolith resting equally on all the balancers. Instead its response is determined by the animal's "mood", in other words the overall state of the nervous system. For example if a ctenophore with trailing tentacles captures prey, it will often put some comb rows into reverse, spinning the mouth towards the prey."


http://en.wikipedia.org/wiki/Ctenophora

"Although the nervous systems of both ctenophores and cnidarians are noncentralized nerve nets, there are certain important differences. In a ctenophore, nonpolar neurons form a diffuse subepidermal plexus. Beneath the comb rows, the neurons form elongate plexes or meshes such that they produce nervelike strands. The bases of the ctenes are thus in contact with a rich array of nerve cells. A similar concentrated plexus surrounds the mouth. However, as in cnidarians, no true ganglia occur, a condition that contrasts markedly with the presence of a centralized nervous system in bilateral Metazoa. The apical sense organ is a statolith that functions in balance and orientation."

(Brusca, Richard C., and Gary J. Brusca. Invertebrates. 2nd ed. Sunderland, MA: Sinauer Associates, 2003. p. 279)

The question is whether the aboral/apical organ, which is at best a very remote analogue of a brain, is itself properly called a brain. This question cannot simply be answered by loosely saying that the aboral/apical organ is the comb jelly's "brain". The true answer is: no! For, strictly speaking, it is incorrect and misleading to say that both humans and comb jellies have brains. Moroz' discoveries haven't altered the fact that comb jellies do not (really) have a brain or CNS.
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Re: Comb Jellies and parallel neural system development

#10  Postby kennyc » May 22, 2014 3:59 pm

:lol: :lol: :lol:

Why don't you just run along home now...
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Re: Comb Jellies and parallel neural system development

#11  Postby Teuton » May 22, 2014 4:06 pm

kennyc wrote::lol: :lol: :lol:
Why don't you just run along home now...


:doh:
(Now I know that arguing with you is a waste of time and effort.)
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Re: Comb Jellies and parallel neural system development

#12  Postby DavidMcC » May 24, 2014 12:47 pm

The problem seems to be the diffuseness of the threshold between "a brain" and "not a brain". There are arguments for and against, but I tend to agree with Teuton, on the whole, at the moment, at least, because the evidence is only for a "proto-brain", at best, in the most sophisticated species of comb jelly.
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Re: Comb Jellies and parallel neural system development

#13  Postby Teuton » Jun 01, 2014 10:53 pm

By the way, I recommend the following book:

* Pagán, Oné R. The First Brain: The Neuroscience of Planarians. New York: Oxford University Press, 2014.

"Planarians, a class of flatworm, are extraordinary: they possess the remarkable ability to regenerate lost body parts, including complete regeneration of the nervous system. If cut into pieces, each piece of the planarian can regenerate into a complete organism. They are also unique among invertebrates in that they display addiction-like behaviors to many drugs abused by humans. Because of these distinct neurological traits, the planarian is often used as an animal model in neurological research, being used most recently for developments in neuropharmacology.
The First Brain is a discussion of how planarians have been used in neuropharmacology, and what role they have played in scientific developments that have a high impact on our culture. Planarians have been the animal models for research in drug addiction, antidepressant development, and various other topics in biology, neurobiology, and even zoology. Pagán uses these flatworms as a framework to explore the history of biological research. The book provides accessible background information on how biomedical research is impacted by evolution, and defines neurobiology and neuropharmacology in ways that are easy to understand. At the same time, Pagán provides enough detail for the book to useful for scientists working in various subsections of biology.
The planarian has played a key role in the history biological, neuropharmacological, and zoological research, and has even made appearances in a few unexpected places in popular culture. Oné Pagán explores all these roles, and shows us why the planarian truly is one of the most extraordinary and influential organisms in scientific research today."


http://global.oup.com/academic/product/the-first-brain-9780199965045?cc=us&lang=en&
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Re: Comb Jellies and parallel neural system development

#14  Postby Teuton » Jun 01, 2014 11:05 pm

DavidMcC wrote:The problem seems to be the diffuseness of the threshold between "a brain" and "not a brain". There are arguments for and against, but I tend to agree with Teuton, on the whole, at the moment, at least, because the evidence is only for a "proto-brain", at best, in the most sophisticated species of comb jelly.


Take a look at the right upper corner of this picture that belongs to a paper by Prof. Moroz: The word "brain" is put between quotation marks. Ctenophora (comb jellies) can at best be said to have rudimentary protobrains or brainoids.

Image
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Re: Comb Jellies and parallel neural system development

#15  Postby kennyc » Jun 01, 2014 11:57 pm

Still stuck in your rut I see....none of this is really relevant to the results of the study. Please learn to be less didactic and more open to new science. Carry on.
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