How to get a single cell

The key to my summer research is isolating a single bacterial cell.  There are a variety of ways to do this.  The primary way my lab does this is by micromanipulation -- that is, physically picking up a single bacterial cell and moving it away from everything else.  Micromanipulation is done using a manipulator attached to a microscope.  Here's one of the micromanipulators in lab:

If you look carefully just slightly above and to the left of the microscope stage, there's something that looks like a metal rod.

micromanipulator with capillary tube

That is the micromanipulator.  At the end of the rod is a very small glass tube called a capillary tube.  The tube is attached to a hollow rod that filled with first air and then further up oil.  The rod then continues as tubing that comes over to the left side of the microscope.  On that side, you can see a much bigger tube, a pump, with a knob on the end.

the pump

That pump allows you to change the pressure inside the capillary tube.  What this means is that if you turn the knob one direction, you can pull liquid into the capillary tube.  If you turn the knob the opposite way, liquid is expelled.  Basically, that thing is a very carefully controlled straw.

So the micromanipulator can suck up things.  But only very small things since the capillary tube is so small.

Next, how do you select what to suck up?  The manipulator can be moved around the stage of the microscope using a joystick.

the joystick

Yes, its just like any video game joystick.  With the joystick, you can move the micromanipulator in three dimensions. 

Let's put this all together.  On the microscope stage, you put a small puddle of liquid with the broken up termite gut.  Then you move the micromanipulator so that the capillary tube is positioned just next to the cell you like.  Next, you turn the knob on the pump and suck up your cell.  Finally, you move the micromanipulator to a clean puddle and drop your cell down.  Repeating this process a few times with the same cell washes it clean.

Your cell is then ready to have its DNA played with! 


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