Thursday, July 8, 2010
And more DNA gels
First, the digestion is supposed to take around 30 minutes. This is helpful because it means that you can make sure that you are just digesting to 146bp and not overdigesting. Ours is taking 5 minutes. In our next digestion, we'll try decreasing the amount of nuclease (the thing that "eats" the DNA) by a factor of 10. Hopefully we'll then see a little more of a progression and less of a step function.
The second issue is that the gel still doesn't look great. The first issue is the ladder. We obviously didn't run long enough: Our 100bp standard only went about 1/2-way down the gel. However, conditions were controlled enough the last time that we should be able to have a nearly-perfectly timed run.
The other issue with the gel is that the DNA in all but the ladder lane is quite diffuse. It would be much easier to read if they looked like lines, similar to the ladder in previous gels. My theory is that this is due to the sample not being dense enough when loaded and therefore diffusing before it starts running in the gel. An easy fix for this will be to increase the amount of sucrose before loading these samples.
Finally, a problem with the gels that I'm not showing you is that I messed up the loading of the other gel. This is actually Travis's gel. Mine didn't have a ladder! Well, I'll have to do better next time.
Things with John's project are going quite well as you can see by his posts. We should have nitrogen tomorrow which will allow him to run more samples. After that starts up, we should be on our way to having all of the DNA aggregation samples done by the end of next week if everything goes well.
Posted by Prof. Andresen at 4:52 PM