The
neuromuscular synapse
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| Figure
1. Acetylcholine receptors labeled with a-bungarotoxin |
The
neuromuscular junction has been widely used for studying the
different aspects of synapses in general.There are several
reasons for this. The synsapse is large in size and easily
accessable, finally it it relatively simple in that only one
motor axon innervates one fibre.
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| Figure
2. Schematic drawing of proteins anchoring the AChR at the
neuromuscular synapse |
A
large array of molecules is necessary to form the clusters of
Acetylcholine receptors (AChR) and to keep up the structured
arrangement of the synapse. One of these proteins is rapsyn,
a 43KD protein essential for the formation
of the synapse (Figure 2 ). By overexpressing wild-type and
mutant versions we are investigating the function of these proteins
on the synapse in living, adult animals.
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Muscle
nuclei
The
cell nucleus can be regarded as the factory of the cell. Both
a blueprint (DNA/RNA) and production machinery (ER/Golgi apparatus)
are associated with it, and most cells in the body are equipped
with one nucleus. Muscle cells are huge on a cellular
scale, more than 10 000 times the volume of a large mononucleated
cell. Because of their size, muscle cells meet a lot of challenges
when it comes to delivering the products (proteins and nucleic
acids) to the different parts of the cell. For this reason,
muscle cells are multinucleated, and contain thousands of nuclei
orderly distributed along the fiber length.
By using a novel in vivo approach to labeling nuclei, we are
investigating the number and distribution of myonuclei under
varying conditions and at different stages of an animal's life.
A dye is injected into the muscle cell (A) and the injected
cells can be identified after several weeks (arrow in B). Specially
engineered software is used to analyze the distribution and
cytosolic domain sizes for each nucleus, and how these parameters
are changed under various conditions, like denervation (E),
training and ageing (C). |
