Most gel excisions stink. Qiagen and Promega tend to claim 80%+ efficiencies that aren’t really achievable. Here I’m describing Jen Sheen’s SiO2 method for DNA purification from agarose: http://www.plantmethods.com/content/pdf/1746-4811-6-1.pdf
If you are new to the lab bench, and perhaps even if you’re not, you may not know how to make loading dye for agarose gels. Its the sort of thing that tends to get made rarely and then persist, so people often inherit a supply and have no idea how to make more when they run out. For this sort of thing the best reference is the relevant appendix at the back of the Sambrook et al. Molecular Cloning text books (near Megan’s desk) and, of course, there is Google. Or, you can just do what I do. My recipe is incredibly simple and would be close to the cheapest option too. Continue reading
Cutting a slice from an agarose gel in order to size select DNA or to isolate a PCR product etc. is standard practice in lab genetics. This post is about how I do it in our lab, (as of Feb 2012).
There are three features of my current method that may be unfamiliar to you even if you’ve done this sort of thing before:
- The Dark Reader transilluminator.
- Sigma X-Tracta gel punches.
This post is about quantifying DNA samples in the Rieseberg lab, i.e. using the tools we have available to us in our lab in the Biodiversity building as of November 2011.
There are three ways to quantify the amount of DNA in an aqueous solution (e.g. DNA dissolved in water or TE):
- Nanodrop (spectrophotometry).
- Qubit (flourometry).
- Agarose gel with EtBr (also fluorometry -> UV lightbox + your eyes = fluorometer).
- (There is also the BioAnalyzer – I’m going to ignore that here and focus on methods to measure high mw genomic DNA).
These methods have different benefits and limitations but they are all valid and useful.