17. Ostertag’s coups

In 1998, Eric Ostertag, a soft-spoken, no-nonsense, precise Germanic type, came to the lab as a rotation student. Eric was a Wisconsin “cheesehead” who had graduated from the University of Wisconsin at Madison and was another M.D.-Ph.D. student at Penn. He had been a member of my small discussion group in the first-year Genetics course for medical students in 1996, so I knew he was very smart and a deep thinker. During his short rotation in the lab, it became clear that Eric would be an outstanding graduate student. I was very pleased when a few months later Eric told me that he wanted to do his Ph.D. in the lab. Although Eric obtained a lot of data on a number of projects, I discuss only four here.

First, Ostertag wanted to test the new retrotransposition cassette made by DeBerardinis in which enhanced green fluorescent protein, EGFP, a screenable marker for retrotransposition, was substituted for the neo gene. This switching to a new retrotransposition marker can be tricky because the backward intron must go into a site in the gene from which it can be spliced without difficulty, but Ralph had been able to find such a site in the EGFP gene. The only problem was the cassette just did not work in the cell culture assay.