Cloning is a fickle process that can make even the most seasoned bench scientists scream in frustration. By the time you perform a colony PCR and run the gel to check for your insert, you’ve invested several days in preparing these transformed cells. But then, the unthinkable happens. When you image your gel…the target band is missing.
A few weeks ago, our elementary school held its annual science fair. Owing to the greater-than-usual number of scientists among the parents, the halls of this event were lined with tables staffed by said parents, showing off the wonders of science, tech, and especially biotech. There were at least three stations devoted to various aspects of stem cell research, and the table next to us had kids run simple nucleic acid extractions from wheat germ using detergent and alcohol – my son loved that one, as he pulled out the stringy goop with a q-tip at the end of the process.
My wife and I contributed to the festivities by putting together a presentation on bacterial transformation. I was just about finished working on a colony counter iPhone® app for Promega, so I figured why not try it out in the field: Print out some colorful ersatz bacterial plates, have the kids count the colonies using the app (yay, touch screens!) and maybe teach them something about genetic engineering along the way.
Do you count colonies on agar plates? Do you often need to average counts over a series of plates? The Promega Colony Counter app for iPhone® (3GS, 4S, and 5) and iPod® Touch (4th and 5th generation) allows you to take a picture of your plate, obtain a good first-guess count and refine it quickly by marking additional colonies and masking areas where the app may have over-counted.
The app is available for purchase for 3.99 USD from the iTunes store in North America and Europe.
When I was teaching I used to show this video to my students, both non-majors and biology majors, because it describes so beautifully what recombinant DNA is, how scientific collaboration works, and how the biotech industry was born. It’s an older video; the technology described is “old hat” for many of us in the life sciences, but it is the technology that got things going, and it’s technology that we still rely on today. Boyer and Cohen (and the film editors) do a great job telling the story of the collaboration that led to the founding of the first biotechnology company and the birth of what is now a burgeoning field.
At one time this video existed as part of a longer interview in which both Boyer and Cohen talk about the teachers and inspirations that led them into science careers. Unfortunately that is not available on YouTube, but if you can find a copy and you are working with students, I highly recommend it.
Escherichia coli remains the first choice of many researchers for producing recombinant protein for functional studies due to its ease of use, well established protocols, rapid cell growth and low cost of culturing. Researchers often need to clone using an E. coli host with good transformation characteristics first, then transfer the desired clone to the expression host. We have developed a new E. coli host KRX, that provides protein yields comparable to those of BL21(DE3) but with much higher transformation efficiencies. Continue reading “Efficient Cloning and Expression of High Protein Yields Using KRX Cells”