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The Immortal Jellyfish
03-11-2009, 02:06 PM,
#1
The Immortal Jellyfish
telegraph.co.uk Wrote:'Immortal' jellyfish swarming across the world
An 'immortal' jellyfish is swarming through the world's oceans, according to scientists.
Last Updated: 1:31PM GMT 30 Jan 2009
[Image: jellyfish_1247566c.jpg]
An 'immortal' jellyfish is swarming through the world's oceans, according to scientists. Photo: BARCROFT
The Turritopsis Nutricula is able to revert back to a juvenile form once it mates after becoming sexually mature.
Marine biologists say the jellyfish numbers are rocketing because they need not die.Dr Maria Miglietta of the Smithsonian Tropical Marine Institute said: "We are looking at a worldwide silent invasion."
The jellyfish are originally from the Caribbean but have spread all over the world.
Turritopsis Nutricula is technically known as a hydrozoan and is the only known animal that is capable of reverting completely to its younger self.
It does this through the cell development process of transdifferentiation.
Scientists believe the cycle can repeat indefinitely, rendering it potentially immortal.
While most members of the jellyfish family usually die after propagating, the Turritopsis nutricula has developed the unique ability to return to a polyp state.
Having stumbled upon the font of eternal youth, this tiny creature which is just 5mm long is the focus of many intricate studies by marine biologists and geneticists to see exactly how it manages to literally reverse its aging process.

devbio.com Wrote:Cheating Death

The Immortal Life Cycle of Turritopsis

While colonial animals can have their immortality, solitary individuals are doomed to die. Hydrozoan cnidarians usually have a complex life cycle, wherein a colonial stage leads to the sexually mature, solitary, adult stage. Eggs and sperm from solitary, sexual, adult medusa (jellyfish) develop into an embryo and planula larva, and they then form the colonial polyp stage. Medusae are formed asexually from polyps. These medusae have a limited lifespan and die shortly after releasing their gametes (Martin, 1997; Figure 1).
[Image: ch02fecycle.GIF]
Figure 1 Life cycle of a typical hydromedusan cnidarian. (After Brusca and Brusca, 1990.)

The hydrozoan Turritopsis nutricula has evolved a remarkable variation on this theme, and in so doing appears to have achieved immortality. The solitary medusa of this species can revert to its polyp stage after becoming sexually mature (Bavestrello et al., 1992; Piraino et al., 1996). In the laboratory, 100% of these medusae regularly undergo this change. Thus, it is possible that organismic death does not occur in this species!

How does Turritopsis accomplish this feat? It can do this because it can alter the differentiated state of a cell, transforming it into another cell type. Such a phenomenon is called transdifferentiation, and it is usually seen only when parts of an organ regenerate. However, it appears to occur normally in the Turritopsis life cycle (Figure 2). In this transdifferentiation process, the medusa is transformed into the stolons and polyps of a hydroid colony. First, the umbrella everts and the tentacles and mesoglea (the middle layer) are resorbed. The everted medusa attach to the substrate by the end that had been at the opposite end of the umbrella, and spawning occurs shortly thereafter. The cnidarian then secretes a perisarc (stolon covering) and stolons. Two days after the stolons are first seen, polyps differentiate. These polyps feed on zooplankton and soon are budding off new medusae.
[Image: inversion.GIF]
Figure 2 Transformation pathways of sexually mature (14-16-tentacle) medusae of Turritopsis nutricula. (After Piraino et al., 1996.)

The cells that accomplish the building of a new stolon are probably those of the exumbrella (the upper portion of the jellyfish dome). Transformation into stolons only occurs in fragments that contain tissues of the exumbrella and the ring canals, and the exumbrella tissue is the only tissue of the medusa that can transdifferentiate into the perisarc-secreting epidermal tissue of the stolons (Piraino et al., 1996). (The endoderm of the ring canals probably becomes the endoderm of the stolon and polyps.) It is not known whether the sensory cells, myoepithelial cells, and cnidocytes are derived from the exumbrella or the endodermal component.

Turritopsis nutricula is the first case in which a metazoan is capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage. Thus, it appears that it has cheated death and is a potentially immortal, solitary metazoan.

Literature Cited

Brusca, R. C. and Brusca, G. J. 1990. Invertebrates. Sinauer Associates, Inc., Sunderland, MA.

Bavestrello, G. Sommer, C., and SarĂ¡, M. 1992. Bi-directional conversion in Turritopsis nutricula. In Aspects of Hydrozoan Biology. (J. Bouillon et al., editors). Sci. Mar. 56 (2-3): 137-140.

Martin, V. 1997. Cnidarians. In Embryology: Constructing the Organism. (S. F. Gilbert and A. M. Raunio, editors). Sinauer Associates, Inc., Sunderland, MA. pp. 57-86.

Piraino, S., Boero, F., Aeschbach, B., and Schmid, V. 1996. Reversing the life cycle: Medusae transforming into polyps and cell transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa). Biol. Bull. 90: 302-312.

B)quite awesome.

If Thine I that I spy with my own little I Doeth Offend thee ; Pluck It out.

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03-11-2009, 03:41 PM,
#2
The Immortal Jellyfish
I agree. On the other hand, I have almost lost respect towards what scientists say and what scientists "know" about life. There are bacteria, even mosqito's, that survive space travel, which does not fit into any scientific scheme. Instead of observing and learning (and wondering), scientists used to spell fancy theories and adapt their observations to their fancy theories. This is coming to an end, luckily, but it takes another generation or two until we can talk about a natural or realistic science.

This applies not to all disciplines of course. Mathematics and geometry, music theory, acoustics, are quite well developed and mirror a great deal of reality. Others like medicine, physics, biology are really in a bad state.


Nice find, by the way.
I am my savior
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03-18-2009, 01:06 PM,
#3
The Immortal Jellyfish
speaking on the scientific community's behalf, I would say that in most cases they are the ones making observations here.

Heres a fancy notion. The earth is flat. Many scientists considered this to be true because that was the idea of the time. They devised many theories to explain this "well known fact". Then along comes some crazy loon saying the earth is in fact round. Now after a few years of everyone agreeing with that theory it is now in fact, a fact. If the scientific community was how you described then all it would take is one guy with a crazy notion and we are back to the earth flat thing. I afraid scientists DO know a thing or two. mostly do do with science. Just don't ask them to do taxes or go to the launderette.

The fancy notions with theories to fit comes strongly from the religious end of the scientific spectrum. "god, did it. See? occam's razor. simplest explaination..." yes yes except for the overuse of assumption. I dont trust doctors to know what they are giving me any more than any other drug dealer. Im pretty sure the guy making the stuff knows what to expect from such medication.

All im saying is. we have moved on from alot of speculation to agreed apon facts. Agreed as in NO OTHER PLAUSIBLE THESIS EXISTS. That does not say we know everything. We just know more than we did.
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03-20-2009, 01:31 AM, (This post was last modified: 03-22-2009, 12:36 AM by JazzRoc.)
#4
The Immortal Jellyfish
Quote:Others like medicine, physics, biology are really in a bad state.
Wow. Wow. So you live in the 16th century.
Or, I notice that your quill pen and ink are well-used, and adapted to the asymmetric digital subscriber line, even though it's in a "bad state".
How did you make your time machine? Wood and boiled bones for glue? Was it the magic spell that made the difference?
Was it the forward travel through time that... (falls asleep)

EDIT (having woken up again - old age, and all that...) This animal isn't the only immortal living thing: there is a tree that grows by rooting vegetatively, and pushes up a new trunk and so on, that has been doing so for tens of thousands of years and now occupies tens of square miles. It is Australian, but sorry, I cannot recollect its name (old age again).
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