May 1, 1997
Vol. 16, No. 16

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    Preuss named Searle Scholar

    One of 15 young investigators to receive award Daphne Preuss, Assistant Professor in Molecular Genetics & Cell Biology, has been named a Searle Scholar for 1997. The award, which this year went to 15 young investigators in chemistry and biology, provides each recipient with $180,000 in research funding over three years.

    Preuss studies the genetics of reproduction in Arabidopsis thaliana, a self-pollinating flowering plant that has emerged as the "fruit fly" of the plant kingdom for its ease of laboratory growth and genetic manipulation. In 1994, Preuss was part of a team that discovered in this small, inconspicuous weed a particular mutation that allows plant geneticists to study the behavior of the chromosomes during sex cell formation in a way that had not been previously possible in higher plants.

    Preuss, who joined the faculty in 1995, is interested in the molecules that male and female plant cells use to communicate during reproduction to guarantee successful fertilization. Normally, once male pollen granules have settled upon the female pistil, they grow pollen tubes toward the eggs deep within the flower in a race to deliver their sperm. The pollen tubes grow with near-perfect efficiency, avoiding eggs that have already interacted with other pollen tubes, probably responding to both attractive and repellent signals from the female parts of the flower.

    Last year, in a paper published in Science, Preuss and graduate student Laura Wilhelmi identified mutations in Arabidopsis that leave the pollen tubes wandering aimlessly about the pistil, unable to find and fertilize an egg. The genetic change results in mutant plants that are incapable of fertilizing themselves, but which can still pollinate or be pollinated by normal plants -- a genetic event similar to what plant biologists think occurred over and over again in evolution as plant species tended toward self-sterility to force outcrossing and maintain a wide genetic diversity.

    The finding was of broad interest to biologists because the phenomena of cell adhesion and guidance are similar to the processes that occur in the outgrowth of axons from neurons during the development of the nervous system in animals. Understanding the genetics and molecular basis of fertilization would be useful for crop engineering, where breeders may desire sterility in one generation and fertility in the next. Arabidopsis, a member of the mustard family, is related to such important crop plants as cabbage, broccoli, cauliflower, rape seed and bok choy.

    Before coming to Chicago, Preuss was a post-doctoral researcher at Stanford, where she received fellowships from the National Science Foundation and the American Cancer Society. She received two bachelors degrees, both summa cum laude, in 1985 from the University of Denver: one in chemistry and one in natural sciences. She received her Ph.D. in biology from MIT in 1990.