Today’s post will be brief but it’s been long since I showed you some nice pics and it is due time now for some joy. This once with a set of images courtesy of some colleagues from the lab. You´ll love them!
We start with an image from a group of hippocampal neurons (which if you remember belong to that area important for learning and memory we’ve talked about numerous times here),from the CA1 region, labeled with a red fluorescent protein, RFP, via a direct transformation through electroporation. This technique consists on introducing DNA into a cell by destabilizing the cell membrane thanks to an electrical current that alters the voltage of said membrane creating pores in it through which DNA can pass through, this way the DNA we introduce in the neuron can be expressed by it and produce the red protein we can later see under the fluorescence microscope
Next I show you a brain slice culture transfected this time again with a red protein, tdTomato, but using a different approach: a gene gun. The way this gun works is by literally shooting the DNA particles embedded in some inert particle, usually gold beads, into cells. By shooting it, the DNA can go through the cell membrane and end up expressed by the target cells giving place to an image like this. Cool, right?
In this other one we can see 4 different slices of a in-depth series from the dendrite of a neuron belonging to mouse visual cortex (primary visual cortex V1) in this case labeled with a green protein that shows activity: GCaMP3. Therefore, the reason we can see these structures is because they are active when visually stimulated. The small little bead-like structures that can be observed over the surface are the so called dendritic spines that constitute the structural markers of neuronal activity, since synapses are located on them -remember, synapses are the connecting points between neurons where information is transmitted-.
Last one of today’s represents another group of neurons from the mouse visual system, although this time we can see them full-length. In this 3D section we can appreciate the cell’s soma at the bottom and from there we can see the apical dendrites sprouting up and going through all apical layers until they ramify into this nice tree-top like structure, in the area of interaction with other apical neurons that have both their somas and dendrites in that area, but that you cannot see here because they are not labeled. This time like before they are labeled with that red protein, tdTomato, only this time the vehicle was a virus. But not any kind of virus, this virus was modified as to be specific for a certain subpopulation of neurons so that we can only see a few of them and we can actually resolve them in full. Remember there are around 860 million neurons in your brain, so unless you select what to see it would be more than hard to see anything (the trees and the forest, you know).
In summary, I have shown you brains and neurons in different colors and I’ve also told you some ways by which we achieve this images in the lab. Hope you liked it. By the way, I forgot to mention: the last two images were taken in vivo. And that except the brain slice, all other images were taken with 2-photon microscopy.