Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When a fish becomes fluid

17.12.2018

Fluidity transition in zebrafish embryo necessary for development – Study published in Nature Cell Biology

Zebrafish aren’t just surrounded by liquid, but turn liquid - in part - during their development. As the zebrafish embryo develops from a ball of cells to a fully-formed fish, a region of the embryo switches its phase from viscous to liquid in a process known as fluidity transition.


Cells lose contacts between each other during fluidization. Cells remain in tight contact when fluidization is impaired.

Nicoletta Petridou

Such fluidity transition has long been speculated to exist in living matter, but is described for the first time to occur in a living organism in a study published today in Nature Cell Biology.

The study was carried out by the group of Carl-Philipp Heisenberg at the Institute of Science and Technology Austria, with first author and Postdoc Nicoletta Petridou, and together with the group of Guillaume Salbreux at The Francis Crick Institute and Edouard Hannezo, also at IST Austria.

Zebrafish are particularly suited for studying animal development as the embryo is transparent and develops outside the mother. At the very beginning of zebrafish development, a tissue layer, the so-called blastoderm, spreads over the yolk. The blastoderm changes shape to form a dome, hence this process is known as ‘doming’.

In the study, Petridou et al. investigated the mechanical forces at play during this shape change. By applying pressure to embryonic tissue through a pipette and measuring how fast it deforms, the researchers could infer how viscous or fluid the tissue is: tissue that deforms slowly is more viscous/less fluid than tissue that deforms quickly.

Repeating the experiment at several time points and regions in the developing embryo, the researchers found that during doming, the tissue suddenly fluidizes at a very specific time and tissue region.

“Such a fluidity transition was predicted to happen by theory and models, but here we show for the first time that it happens in a real, living organism”, says first author Nicoletta Petridou.

Lost in division

Why and how does zebrafish tissue become liquid? In “normal” viscous tissue, the cells are in close contact with each other. The authors found that the fluidity transition happens because cells keep on dividing during development. During division, the cells become round and detach from their neighbors.

The more the cells divide, the more connections are lost between them, until they eventually lose so many contacts that the tissue turns liquid. “This is a mechanical and not biochemical change”, explains Petridou, “The embryo is programmed to divide, it cannot escape it.”

All cells in the embryo divide, however, and the researchers observed that only a very specific region of the tissue, the central region of the blastoderm, became fluid. They then looked for a process that would prevent other areas of the embryo from turning fluid.

A certain signaling pathway, the non-canonical Wnt signaling pathway, stopped the fluidity change at the margins of the embryo, says Petridou. “Non-canonical Wnt signaling keeps cells connected and allows the embryo margins to bypass fluidization. We think that the default of the tissue is to become fluid, but the signaling keeps specific areas from turning fluid.”

A sudden change

When the fluidity transition goes wrong – either because the researchers stopped Wnt signaling so that all areas of the blastoderm become fluid, or because they inhibited fluidization in the entire blastoderm – doming is impaired and the embryo progresses more slowly during early development.

“Our study shows that regulated changes in tissue material properties play an important and significant role in morphogenesis”, summarizes Petridou. But the authors might also have found first signs of a well-known concept of physics happening in a living organism.

The very sudden transition from viscous to fluid in the blastoderm resembles a well-known concept from physics, the phase transition. “Phase transitions, such as when water boils, happen suddenly. We called the phenomenon observed in zebrafish ‘fluidity transition’ as we are not certain that it is, in fact, a phase transition in the true sense of physics”, explains Petridou, “However, we are working further to define whether this is a phase transition. Phase transitions can happen in molecular networks, but we don’t yet know if they can happen in a tissue or in an embryo.”

About IST Austria
The Institute of Science and Technology (IST Austria) is a PhD-granting research institution located in Klosterneuburg, 18 km from the center of Vienna, Austria. Inaugurated in 2009, the Institute is dedicated to basic research in the natural and mathematical sciences. IST Austria employs professors on a tenure-track system, postdoctoral fellows, and doctoral students. While dedicated to the principle of curiosity-driven research, the Institute owns the rights to all scientific discoveries and is committed to promote their use. The first president of IST Austria is Thomas A. Henzinger, a leading computer scientist and former professor at the University of California in Berkeley, USA, and the EPFL in Lausanne, Switzerland. The graduate school of IST Austria offers fully-funded PhD positions to highly qualified candidates with a bachelor's or master's degree in biology, neuroscience, mathematics, computer science, physics, and related areas. http://www.ist.ac.at

Wissenschaftliche Ansprechpartner:

Carl-Philipp Heisenberg
Tel: +43 (0)2243 9000-3901
E-mail: heisenberg@ist.ac.at

Originalpublikation:

'Fluidization-mediated tissue spreading by mitotic cell rounding and non-canonical Wnt signalling', Nicoletta I. Petridou, Silvia Grigolon, Guillaume Salbreux, Edouard Hannezo, and Carl-Philipp Heisenberg. DOI: 10.1038/s41556-018-0247-4.

Weitere Informationen:

https://ist.ac.at/en/research/research-groups/heisenberg-group/

Dr. Elisabeth Guggenberger | idw - Informationsdienst Wissenschaft

More articles from Studies and Analyses:

nachricht Deep Brain Stimulation Provides Sustained Relief for Severe Depression
19.03.2019 | Universitätsklinikum Freiburg

nachricht AI study of risk factors in type 1 diabetes
06.03.2019 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>