The track to learning how to use the tools in the lab leads us with surprising turns. For example, the Singer RoToR is something we thought we understood and start using with reliability. Every time we believe we sorted out the problems we run into new one.
Yesterday, Ayelet decided to copy the GFP-tagged library so that we can have fresh copies to use for picking up strains. What worked fine the previous day, suddenly decided to cause problems. Once again the de-liding arm didn't pick up a plate lid. Unlike the previous event which lead to a cascade of escalating problems, this time the resetting worked fine. But only on the forth attempt (with a complete reset after each one) things went back to normal.
In previous rounds of copying, we had problems with the colonies at the corners of the plate. Our thinking was that the agar is starting to dry and thus is no longer flat. To avoid this problem, Ayelet increased the pressure of the tips onto the agar. This solved the corner problem, but lead to a new one. Since we used fresh plates, the extra pressure on the target plate caused the pins to puncture the agar. Instead of putting cells on the surface, we now have them in small craters. Today, after some growth the colonies look more like starbrusts than the disk shape they should take.
One worry is that copying from these plates will be difficult since the colonies are not growing upwards but rather inwards.