An Experiment

I am a scientist. I run a small research lab that works on some specific DNA in yeast. I have undergraduates and Masters students doing research in my lab. I also teach at my University, typically three classes a term. My research students also take classes, so none of us have the kind of dedicated time to do science that I was used to as a graduate student and a post-doc. I do not have the time to monitor my researchers as closely as might be ideal, and only going to Masters, as soon as a student is trained they are moving on.

I was on a half sabbatical in England two years ago. To both my pleasure and dismay, I accomplished more in 5 months by myself there than all my students combined over 9 years here. Part of that is due to facilities, part due to training, and part to having or not having intellectual colleagues to help with ideas and trouble-shooting.

Nonetheless, this afternoon I am happy.

I have a grad student who has taken rather longer than usual to complete her Master's research. Part of that is due to have two babies while in grad school. Having babies and being a parent tending them will slow down other aspects of life, as it should. Fortunately there is little time pressure on how long you take. But part was a series of technical problems. My student was a good student, but I did not always have the time to supervise her as closely as might be ideal. Sometimes she didn’t do every control she needed, other times she might slip up on a technique I could have caught if I had been paying closer attention.

Finally she had made it through all her earlier technical problems and had successfully made all the genetic changes necessary for her actual experiment. This was not trivial, creating the right cells to compare with normal ones. She did the experiment (involving mating and inheritance patterns) on the cells without the genetic changes. Then did the experiment with the altered cells and suddenly the experiment failed. There were no mated cells. She had not used the original strains for her controls as she should have. Nonetheless, something was very wrong. She repeated it a couple of times, still without t the controls unfortunately, and the experiment simply did not work. My fear was that there was something wrong with the strains she had laboriously created over the past couple of years. Meanwhile, my student's husband needed to move on to his fellowship, and she HAD done a lot of work. So I told her to go and write her thesis. Even though we did not have the answer, she had done enough work for a Masters.

Over the Spring and first part of summer I had undergrads in my lab learning about research. I taught them how to grow the cells, isolate DNA and had them check the altered strains step by step. Everything we checked was working, yet the experiment still failed. It was as if something was killing the cells.

At the end of the term I looked hard at the sterilized filters in the container we put them in to be sterilized we were using.

They looked wrong.

No one knew exactly what they were and where they came from.

I became suspicious that they were a filter type that binds permanently to proteins. Cells would never be released to grow. I was particularly suspicious when I could not find the right filters in their original boxes anywhere in the lab, though there was several containers of the wrong ones (unsterilized).

So I ordered the right filters. I started growing the cells, made sure they were up to growing fast and healthy. Then put in a 14 hour day last Wednesday repeating the experiment, with lots of controls.

It Worked! There are plenty of mated cells that grew into colonies. Now over the next few days, I will grow the colonies up, then isolate their DNA, then cut it, separate it by size on a gel, make some radioactive probes, and see if their inheritance pattern has changed. Finally I can analyze them and find out the answer to the original question.

The grad student says that yes, at the beginning she used filters I had prepared, then she ran out and sterilized the next batch herself. She asked me about the filters, I told her where to find them, and did not think to double check to make sure we hadn’t accumulated the wrong variety. If only I had noticed the filters looking wrong a year ago.