Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cytoplasm of scrambled frog eggs organizes into cell-like structures, Stanford study finds

07.11.2019

Can scrambled eggs unscramble themselves? Well, sort of.

The cytoplasm of ruptured Xenopus frog eggs spontaneously reorganizes into cell-like compartments, according to a study by researchers at the Stanford University School of Medicine.


After being scrambled, the cytoplasm of Xenopus frog eggs spontaneously reorganizes into cell-like compartments. Nuclei are blue; microtubules are green; the endoplasmic reticulum is red.

Credit: Xianrui Cheng/Stanford Medicine

"We were gobsmacked," said James Ferrell, MD, PhD, professor of chemical and systems biology and of biochemistry. "If you blend a computer, you'd end up with tiny bits of computer, and they wouldn't even be able to add two and two. But, lo and behold, the cytoplasm reorganizes."

Remarkably, the self-assembled compartments retain the ability to undergo division and can form smaller compartments. Previous studies have shown that some subcellular structures, such as centrosomes and endoplasmic reticulum, can self-assemble outside cells from their purified components, demonstrating that these structures have some ability to self-organize. However, the new study provides the first example of self-organization at the scale and complexity of entire cells.

Ferrell is the senior author on the study, which will be published Nov. 1 in Science. The lead author is postdoctoral scholar Xianrui Cheng, PhD.

Compartments form spontaneously

The discovery relied on Cheng's observations. While studying a molecular process known as programmed cell death, he noticed the nuclei in a tube of cytoplasmic extract from frog eggs were behaving unexpectedly. After 30 minutes or so, the nuclei had organized so the distance between two nuclei was almost equal, Cheng said. When he imaged the cytoplasmic extract on microscope slides, he saw that it had formed distinct compartments that resembled a sheet of cells.

"If you take the cytoplasm of the frog egg -- note that the cytoplasm has been homogenized, so whatever spatial structure that was there has been completely disrupted -- and just let it sit at room temperature, it will reorganize itself and form small cell-like units. That's pretty amazing," Cheng said. These cell-like compartments formed whether or not Xenopus sperm nuclei were added, suggesting that the behavior relied on something intrinsic to the egg.

To understand the mechanism underlying the phenomenon, the researchers tested whether compartment formation was affected by the addition of chemical inhibitors to cytoskeletal proteins, motor proteins and kinases, which activate other proteins. This approach revealed that ATP, the primary source of energy in the cell, and microtubules, cytoskeletal filaments that provide structural support, were required for compartments to form. Dynein, a type of motor protein, was also required for proper microtubule localization.

Self-organized compartments divide

These cell-like compartments not only looked like cells; they divided like them, too. The egg extract that the researchers used when they identified compartment formation contained a chemical that prevented the cells from entering the cell cycle. When this chemical was removed, and sperm nuclei were added, the egg extract formed compartments that divided into smaller compartments.

The researchers saw that these compartments could undergo over 25 rounds of division, indicating that the process was very robust. The division was also reductive, Cheng said, since the total amount of cytoplasm remained constant and was being divided into smaller and smaller compartments with each cycle. "You're taking the material from the egg, and it divides in a mode that's reminiscent of embryonic development," he said. "Just like they're supposed to in a real egg."

Future directions

All of these findings suggest that the Xenopus egg cytoplasm has the intrinsic ability to generate the basic spatial organization of the cell and even has some of its functions. An open question, however, is what role this phenomenon plays in the normal physiology of the egg. Another question is whether this ability to self-organize is peculiar to eggs or is shared by other types of cells.

The researchers also hope to further understand what's needed for self-organization to occur. "My favorite question right now," Ferrell said, "is can we make a simple model that explains the basics of this organization process? Or do we have to do something extremely complicated, like account for every single thing that we know a microtubule can do?"

###

Ferrell is a member of Stanford Bio-X, the Stanford Cancer Institute and the Wu Tsai Neurosciences Institute at Stanford.

The research was supported by the National Institutes of Health (R01GM110564 and P50GM107615).

Stanford's departments of Chemical and Systems Biology and of Biochemistry also supported this work.

The Stanford University School of Medicine consistently ranks among the nation's top medical schools, integrating research, medical education, patient care and community service. For more news about the school, please visit http://med.stanford.edu/school.html. The medical school is part of Stanford Medicine, which includes Stanford Health Care and Stanford Children's Health. For information about all three, please visit http://med.stanford.edu.

Print media contact: Rosanne Spector at (650) 725-5374 (manishma@stanford.edu)

Broadcast media contact: Margarita Gallardo at (650) 723-7897 (mjgallardo@stanford.edu)

Rosanne Spector | EurekAlert!

Further reports about: Medicine Xenopus cell-like structures cytoplasm cytoplasmic eggs microtubule nuclei proteins

More articles from Health and Medicine:

nachricht Sheffield scientists identify new potential treatment pathway for cardiovascular disease
04.11.2019 | University of Sheffield

nachricht A new material for regenerative medicine capable to control cell immune response
04.11.2019 | Tomsk Polytechnic University

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Distorted Atoms

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...

Im Focus: A Memory Effect at Single-Atom Level

An international research group has observed new quantum properties on an artificial giant atom and has now published its results in the high-ranking journal Nature Physics. The quantum system under investigation apparently has a memory - a new finding that could be used to build a quantum computer.

The research group, consisting of German, Swedish and Indian scientists, has investigated an artificial quantum system and found new properties.

Im Focus: Shedding new light on the charging of lithium-ion batteries

Exposing cathodes to light decreases charge time by a factor of two in lithium-ion batteries.

Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory have reported a new mechanism to speed up the charging of lithium-ion...

Im Focus: Visible light and nanoparticle catalysts produce desirable bioactive molecules

Simple photochemical method takes advantage of quantum mechanics

Northwestern University chemists have used visible light and extremely tiny nanoparticles to quickly and simply make molecules that are of the same class as...

Im Focus: An amazingly simple recipe for nanometer-sized corundum

Almost everyone uses nanometer-sized alumina these days - this mineral, among others, constitutes the skeleton of modern catalytic converters in cars. Until now, the practical production of nanocorundum with a sufficiently high porosity has not been possible. The situation has changed radically with the presentation of a new method of nanocorundum production, developed as part of a German-Polish cooperation of scientists from Mülheim an der Ruhr and Cracow.

High temperatures and pressures, processes lasting for even dozens of days. Current methods of producing nanometer-sized alumina, a material of significant...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

Smart lasers open up new applications and are the “tool of choice” in digitalization

30.10.2019 | Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

 
Latest News

Oxygen deficiency rewires mitochondria

07.11.2019 | Life Sciences

What and how much we eat might change our internal clocks and hormone responses

07.11.2019 | Studies and Analyses

Scientists crack structure of a novel enzyme linked to cell growth and cancer

06.11.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>