We are developing a method to control gene expression in a temperature dependent manner. Our strategy is to regulate reporter expression with a well-defined promoter at the 5' end and a mutant
fem-3 3'UTR at the 3' end. The
fem-3(gf) mutations map to the
fem-3 3'UTR and release
fem-3 from post-transcriptional repression at 25 C, but not at 15 C (1,2). We have tested expression of a
lag-2 promoter::GFP construct that carries either a strong or a weak
fem-3(gf) 3'UTR. The
lag-2 promoter drives expression in the distal tip cells of adults (3-5). We find that transgenes express GFP at much lower levels at 15 C than at 25 C when carrying a
fem-3(gf) 3'UTR. We are currently trying to optimize repression at 15 C using the
lag-2 promoter and GFP as a reporter. In addition, we are testing whether temperature sensitive repression can be achieved in other tissues, and we are starting to explore the biological activity of various proteins expressed in the distal tip cell. 1. Ahringer, J., and Kimble, J. (1991). Nature 349, 346-348. 2. Barton, M. K., Schedl, T. B., and Kimble, J. (1987). Genetics 115, 107-119. 3. Fitzgerald, K., and Greenwald, I. (1995). Development 121, 4275-4282. 4. Gao, D. and J. Kimble, midwest worm meeting 1996. 5. Henderson, S. T., Gao, D., Lambie, E. J., and Kimble, J. (1994). Development 120, 2913-2924.