Tuesday, 10 July 2012

Neuron as it is, everybody sees.

This is what I work with.

This is a rat neuron in a cell culture. It is already dead – fixed with formaldehyde, to be exact. We grow them on coverslips. This way, it’s easy to make a preparation to watch with the microscope.

Granted, you’re not a hermit living in the woods for the last thirty years and you have probably seen similar pictures in the popular science news. I’ll go one step further and explain what it actually means.

The neuron is stained with two different fluorescent dyes. The green one shows the protein called MAP2. It’s supposed to be present only in the dendrites (Tentacles of a neuron. Now you know.), so it serves as a tool to make them visible with the fluorescent microscope. To stain it, I have used an antibody that binds MAP2, and another antibody that binds to the former one, with a fluorescent dye attached on top.

We need two antibodies that pile up one on another, because it reinforces the signal.
The red stuff is f-actin. Actin is an important component of the cell’s skeleton and it exists in two forms: polymerized and non-polymerized. F-actin is the polymerized one. Look at the red dots that overlap with the green tentacles. These are the dendritic spines. They don’t look spiney at all, but trust me, I’m a scientist. Those little guys make synapses with the axon (Another tentacle of a neuron. Contrary to the dendrites, each neuron has only one axon. You can’t see the axons only because I haven’t stained them).

To stain the spines, I have used phalloidin, a poisonous peptide derived from the death cap mushroom. In this quantity is not even enough to poison a mosquito and more conveniently, it is attached to a red fluorescent dye.

This picture has been taken with the confocal microscope. The colours match the dyes visible with the fluorescent microscope, however I could make them violet and yellow and it wouldn’t matter.

And now look again and behold.

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