November of my junior year of highschool and I am up late finishing off the “Lambda Protocol”, my biology teacher’s attempt to make a lab report on DNA gel electrophoresis sound exciting. Little did I know, as I apathetically analysed my results, that I would be using this technique on a regular basis in my future lab.
Since my lab uses murine lines (mice) for our preclinical trials, we can breed mice with certain genotypes. We then seperate (in our case) the AD + and AD - genes so that we can test the differences in cognition and memory.
The first step is to clip the mice, which means to extract some of their DNA from their tails. We then digest the samples with proteinase k so that the chemical bonds between the two strands of the double helices break. The genes we are specifically interested in are Channelrhodopsin, Cre and the AD gene. We therefore add a primer to the digested samples to target those exact segments of the DNA. The samples are then ready for Polymerase Chain Reaction (PCR), which is a technique used to amplify a single copy of a segment of DNA, so that you can analyse it. After doing the PCR, the samples are ready for DNA gel electrophoresis, which is another technique used in molecular biology (the one I first tried out in highschool) to separate DNA based on size and charge. This allows us to see, through a UV gel imager, which mice are AD +, and which are AD- to use for our tests. This procedure is one of my main responsibilities.
The main thing I have learned from repeated runs of this procedure is that there are so many minute details that can go wrong in the preliminary steps of your experiment. When digesting the DNA, for example, I have to be vigilant not to contaminate the samples, as well as not to skip or duplicate the dosage in a specific vial. The amount of times I have nearly forgotten to change the tip of a syringe or make sure the tip doesn’t touch the bottom or sides of the vial is embarrassing, though I know I will master it some day. Maybe I’ll even be able to listen to music while I’m at it like the cool lab technicians.
