A new advanced method for nano-scale imaging of vesicle-fusion could add to
our understanding of diseases of the nervous system and viral infections. In
the long term, this could be useful in developing a cure for neurological diseases
and mental disorders (e.g. schizophrenia, depression, Parkinson's disease, Alzheimer's
disease).
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| Researchers determine shape and size of the contact area between vesicle and membrane by measuring colour intensity from flourescent molecules. Right: Vesicle marked by acceptor flourescent molecules that light up when close to donor molecules (left). Middle: A plot of the same, calculated FRET. (Credit: Image courtesy of University of Copenhagen) |
Neurons communicate with each other with the help of nano-sized vesicles.
Disruption of this communication process is responsible for many diseases and
mental disorders such as depression. Nerve signals travel from one neuron to
another through vesicles -- a nano-sized container loaded with neurotransmitter
molecules. A vesicle fuses with the membrane surrounding a neuron, releases
neurotransmitters into the surroundings that are detected by the next neuron
in line. However, we still lack a more detailed understanding of how the fusion
of vesicles occurs on the nano-scale.
Associate Professor Dimitrios Stamou, Department of Neuroscience and Pharmacology
and Nano-Science Center from University
of Copenhagen explains: "Contact between vesicles and membranes are
an essential step in many important biological processes. We can now quantify
contact areas formed between vesicles and determine the vesicle size and shape
with nano-scale resolution. This helps us characterise the properties of the
molecules involved in vesicle-fusion. The new method opens great new prospects
for the research of neurological and infectious diseases".
Images on the nano-scale
The researchers are using a method called FRET or Fluorescence Resonance Energy
Transfer. The method is well known, but what is new is the way the researchers
are using it. They produce vesicles in the laboratory, which contain fluorescent
donor molecules, and membranes fixed to a surface. The fixed membranes contain
acceptor fluorescent molecules. Only when the two different fluorescent molecules
are near to each other will light be emitted, which researchers can measure
as a sign of vesicle fusion. By measuring the emitted light the researchers
found new ways to determine the vesicle shape with nano-scale resolution in
real-time.
"We have lacked a method for measuring the fusion of vesicle and membrane
on a nano-scale at the moment the process occurs. Until now it has only been
possible to get a still image of the process with high resolution, or live images
with low resolution. With the new method we can quantify the changes in vesicle
shape live i.e. during fusion, and with nanoscale resolution," explains
Dimitrios Stamou.
This research was recently published in PNAS (July 28, 2009 vol. 106 no. 30
12341-1234.)
Posted October 12th, 2009
