Unraveling jellyfish metamorphosis
27 January 2014
The life cycle of Aurelia contains two alternating
generations - polyps and jellyfish. In the spring, each
polyp transforms into multiple young jellyfish that detach
from each other and start their independent life.
Fertilized eggs produced by adult jellyfish develop into
larvae, which settle down and transform into polyps.
How does one genome create two completely
different body plans in one animal? This was the
question Konstantin Khalturin was attempting to
answer when he began working on jellyfish. The
fascinating story he discovered along the way
answers questions about the regulation of
metamorphosis, an animal changing from one
physical form to another, in the moon jellyfish
Aurelia aurita. In the February 3rd edition of
Current Biology, Khalturin and colleagues working
at the Zoological Institute in Kiel, Germany
described a new hormone responsible for
metamorphosis in jellyfish and linked it to a
common developmental biology pathway found in
more complex animals.
stationary form that anchors to the bottom of the
ocean and reproduces asexually. When the
temperature of the ocean drops during the winter
months for a certain amount of time, the polyps
begin metamorphosis when individual layers of the
polyp bud off and begin turning into the familiar
jellyfish form. This process is called strobilation,
and the polyp at this stage is called a strobila. The
genes responsible for metamorphosis between
polyp and jellyfish remained a mystery until now.
The researchers started by feeding the transitioning
strobila, the actively budding part, to polyps to see
if there was some substance present in the strobila
that could induce metamorphosis. The data
suggested this was true, and polyps fed with
strobila underwent metamorphosis without the drop
in temperature normally required. The researchers
determined that some substance that could move
out of the strobila into the surrounding polyp was
inducing metamorphosis, giving them a clue as to
what type of gene they should look for.
The next step was looking at what genes were
expressed exclusively during the strobila phase.
They identified three excellent candidates. One of
which, called CL390, fits all of their requirements: it
was expressed in the strobila stage, was turned on
when the water temperature dropped and
increased in expression as the temperature
continued to stay cold. The researchers observed
that there was a threshold of time that the water
temperature needed to be low in order for polyps to
undergo metamorphosis. They hypothesized that
this would prevent the polyps from transitioning to
jellyfish too early in winter and not having a
sufficient food source. CL390 seemed to act as a
timer, informing the polyp when the temperature
was low for long enough, meaning winter was
almost over and that it was time to undergo
metamorphosis. When CL390 reached a threshold
of 15 times its expression during polyp stage,
metamorphosis occurred even if the researchers
had transferred the polyps back to a higher
temperature.
Early in development, jellyfish exist as a polyp, a
1/3
Adult moon jellyfish Aurelia aurita.
Khalturin has recently joined the Marine Genomics
Unit of OIST and continues to work on Aurelia
Stages of jellyfish metamorphosis seen using an electron
aurita with a goal to further understand his original
microscope, featured on the cover of Current Biology.
question, how does one genome create two body
You can see the polyp on the bottom right, the strobila
plans? In addition to contributing to our
and the immature jellyfish at the top.
understanding of metamorphosis, this work also
has practical applications. Since they have
identified one of the key elements responsible for
creating jellyfish from polyps, it may be possible to
The researchers also discovered a link between
use this information to prevent jellyfish blooms that
metamorphosis and retinoic acid, a compound
have become common in recent years and can
derived from Vitamin A required in development
devastate fish populations.
throughout the animal kingdom. They linked the
role of retinoic acid and one of its nuclear hormone
More information: "Regulation of Polyp-toreceptors to the CL390 gene, demonstrating that
Jellyfish
Transition in Aurelia aurita." Björn Fuchs,
some common features of higher order animal
development are conserved in these much simpler Wei Wang, Simon Graspeuntner, Yizhu Li,
Santiago Insua, Eva-Maria Herbst, Philipp Dirksen,
animals.
Anna-Marei Böhm, Georg Hemmrich, Felix
Sommer, Tomislav Domazet-Lošo, Ulrich C.
Klostermeier, Friederike Anton-Erxleben, Philip
Rosenstiel, Thomas C.G. Bosch, Konstantin
Khalturin. Current Biology - 16 January 2014. DOI:
10.1016/j.cub.2013.12.003
Provided by Okinawa Institute of Science and
2/3
Technology
APA citation: Unraveling jellyfish metamorphosis (2014, January 27) retrieved 16 June 2017 from
https://phys.org/news/2014-01-unraveling-jellyfish-metamorphosis.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
3/3
Powered by TCPDF (www.tcpdf.org)