The so-called cellular slime mold, a unicellular organism that may transition into a multicellular organism under stress, has just been found to have a tissue structure that was previously thought to exist only in more sophisticated animals.
What's more, two proteins that are needed by the slime mold to form this structure are similar to those that perform the same function in more sophistical animals.
Shortly after an animal embryo forms, it develops a single layer of cells that, shaped like a hollow ball, is empty at its center. Acting as a kind of "man behind the curtain" that directs these cells to organize into this hollow formation are several proteins that help each cell touch its neighbors but keep its top surface exposed to the formation's empty interior.
Even after animals grow beyond the embryo stage, the cells in many organs of their bodies maintain this type of hollow structure. These organs include those in the digestive tracts of animals, which feature a layer of cells, called epithelial cells, that face inward to form a hollow structure and are shaped asymmetrically to give organs their directionality. For example, the asymmetric epithelial cells of animal intestines face inward to form a hollow structure through which nutrients are absorbed. Likewise, the asymmetric epithelial cells of animal glands, such as salivary and endocrine glands, also face inward to form a hollow structure. But instead of absorbing substances as do the epithelial cells of animal intestines, these glandular epithelial cells secrete into their hollow structure substances that they produce.
With funding from the National Science Foundation, Daniel Dickinson, W. James Nelson and William Weis--all of Stanford University--took a careful look at the final, mature stage of slime mold development under a high-powered microscope. They report their results in the journal Science, March 11, 2011.
The slime mold spends most of its life as a single-celled organism, living in soil and preying on bacteria. However when food runs short, thousands of slime mold cells aggregate to form a mound. They then grow into a fruiting body--which is a stalk, a few millimeters tall, whose top peeks over the surface of the ground and holds spores. The researchers found that the organization and directionality of cells in this top part of the extending stalk are surprisingly similar to those of the epithelial cells of some organs of higher animals.
Dickinson and his colleagues also discovered that in order for the cells in the top of the slime mold's stalk to organize into an epithelium, they need analogues to two of the many proteins that are needed by animal cells to organize into an epithelium. Called alpha-catenin and beta-catenin, these slime mold analogues are genetically and biochemically similar to their animal versions. And when the researchers removed these analogues from the cells of slime molds, they lost their ability to organize correctly.
In addition to requiring proteins that are similar to those required by some animal epithelial tissues, the slime mold's epithelium tissue behaves similarly to the epithelial tissue of some animals--it is secretory. It secretes proteins that coat the stalk of the fruiting body and give it the rigidity it needs to send its spores out onto the ground in search of new food.
"We don't know whether the ancient ancestor of slime molds and animals was actually able to form an epithelium," says Dickinson, "but it must have had alpha-catenin and beta-catenin, and we suspect that these proteins had some role in organizing cells."Media Contacts
Lily Whiteman | EurekAlert!
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy