In our brain, information is passed from one neuron to the next at a structure called synapse. At a chemical synapse, a chemical is released from the signal-sending neuron or presynaptic neuron. This neurotransmitter then crosses the synaptic cleft to bind to receptors in the target neuron or postsynaptic neuron. An extensive molecular machinery is at work: for example, vesicles filled with neurotransmitter dock at “docking sites” in the pre-synaptic active zone before they fuse and release the neurotransmitter into the synapse.
A study co-led by Ryuichi Shigemoto, Professor at the Institute of Science and Technology Austria (IST Austria), with Alain Marty, Professor at Université Paris Descartes, uncovers that a single docking site may use a single cluster of calcium channels and that both the number of docking sites and the number of calcium clusters change in parallel with brain age.
This establishes the first clear link between the morphology and function of docking sites. The study was published today in PNAS.
At a chemical synapse, signal transmission requires an elaborate sequence of events. It starts when an electrical signal, the action potential, reaches the synaptic terminal of the presynaptic neuron. This causes voltage-gated calcium channel to open. Calcium ions rapidly stream into the presynaptic terminal and the calcium concentration in the presynaptic terminal rises. This allows synaptic vesicles filled with neurotransmitter to fuse with the plasma membrane and release the neurotransmitters into the synaptic cleft. Speed is essential in information transmission.
Therefore, before the action potential even arrives at the presynaptic terminal, vesicles containing neurotransmitter line up in a fusion-ready state at docking sites in the presynaptic terminal. When the action potential reaches the presynaptic terminal, the vesicles can rapidly fuse and release the neurotransmitter.
Functionally, docking sites limit the maximum number of vesicles that can be released at each action potential, this determines the strength of the synapse. Until now, a clear link between the functional aspect of docking sites and their morphological aspect as sites where vesicles dock could not be established in the mammalian brain.
Shigemoto and colleagues used a high-resolution electron microscopy technique to look closely at the presynaptic terminal of a particular synapse in the mouse. They found that the number of functional docking sites matches the number of clusters of voltage-gated calcium channels in the presynaptic terminal.
In addition, the number of docking sites and the number of calcium clusters change in parallel with brain age and synaptic size. This led the researchers to a major conclusion, as Shigemoto explains: “Based on our results, we suggest that for each docking site, there is a corresponding cluster of voltage-gated calcium channels. We propose a model in which each cluster of calcium channels is surrounded by enough free space to allow one synaptic vesicle to fuse in any direction.”
Ryuichi Shigemoto joined IST Austria as Professor in 2013. He and his group investigate the functional roles of ion channels and neurotransmitter receptors in neurons and glia using morphological, electrophysiological and molecular biological techniques. Shigemoto received an ERC Advanced Grant in 2016. Walter Kaufmann, Staff Scientist in IST Austria’s Electron Microscopy Facility, performed part of the research for the current study.
Bernhard Wenzl | idw - Informationsdienst Wissenschaft
Accelerated reactions in condensed bio-matter?
19.06.2018 | Heidelberger Institut für Theoretische Studien gGmbH
Kidney tumor: Genetic trigger discovered
19.06.2018 | Julius-Maximilians-Universität Würzburg
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
19.06.2018 | Life Sciences
18.06.2018 | Earth Sciences
18.06.2018 | Process Engineering