Throughout their life, plants form leaves and side roots. These two types of organs have something in common: their development is finely tuned by small regulatory RNA molecules, the trans-acting short interfering RNAs (ta-siRNAs). Scientists Dr. Alexis Maizel and Virginie Jouannet at Heidelberg University‘s Centre for Organismal Studies were able to demonstrate how and where within the plant cell these ta-siRNAs are produced. They succeeded in identifying hotspots for the biogenesis of these special RNA molecules. The results of this study have been published in the “EMBO Journal”.
On the left, a normal mouse-ear cress (Arabidopsis) plant, and on the right a plant in which ta-siRNA formation is compromised. The leaf structure of the plant is abnormal. Credits: Alexis Maizel, Virginie Jouannet
The formation of plant organs depends on the presence of proteins that allow cells to divide and take on new shapes and characteristics. The most straightforward route to protein production begins when genes are activated and transcribed into messenger RNAs that are then translated into proteins. However, cells often fine-tune their population of proteins by producing short interfering RNAs (siRNAs): small regulatory molecules that dock onto messenger RNA and cause them to be broken down before they can be used for protein production. Researchers already knew that ta-siRNAs, a type of siRNA, fine-tune the formation of leaves and the growth of side roots by blocking the production of specific proteins. What remained unknown, however, was exactly where in the plant cell the ta-siRNAs were produced.
Ta-siRNAs are created from longer RNA molecules that are whittled down by a complex of other molecules. One essential component of this cutting machine is a protein called AGO7. The Heidelberg scientists have uncovered that AGO7 accumulates in foci, called siRNA bodies, located in the cytoplasm of the cells. SiRNA bodies also contain all the other enzymes needed for the formation of ta-siRNAs. “These foci are therefore hotspots for the formation of the siRNAs, that is the small, regulatory RNA molecules”, explains Virginie Jouannet, a PhD student in Dr. Maizel’s group. In addition, the researchers were able to show that AGO7 could not longer fulfil its functions when released from the siRNA bodies, resulting in problems in the development of the plant.
Two other observations caught the attention of the researchers. For one thing, the siRNA bodies are closely linked to the network of membranes that the cell uses to transport and secrete proteins. “Interestingly, these foci also host viruses and plants defend themselves against viruses using siRNAs”, says Dr. Maizel. “These results reveal a hitherto unknown role for membranes in the biogenesis of RNA and suggest that the generation of siRNA can occur only in specific locations of the cell.”
Dr. Maizel leads an independent research group at the Centre for Organismal Studies at Heidelberg University and is a member of the university’s CellNetworks Cluster of Excellence. Collaborating on the research project were scientists from the Institut des Sciences du Végétal at the Centre National de la Recherche Scientifique (CNRS) in Gif-sur-Yvette as well as the Institut Jean-Pierre Bourgin at the Institut National de la Recherche Agronomique (INRA) in Versailles (France).
For information online, see http://www.cos.uni-heidelberg.de/index.php/independent/a.maizel?l=_e
Marietta Fuhrmann-Koch | idw
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research