Contents

15 April 1988
Vol 240, Issue 4850

About The Cover

Auxotrophic trp1-1 mutants of Arabidopsis thaliana, blocked in anthranilate phosphoribosyl transferase, are fluorescent under ultraviolet light due to accumulation of intermediates in the pathway of tryptophan biosynthesis. The middle column of fluorescent mutant plants is surrounded by larger, nonfluorescent wild-type A. thaliana plants. See page 305. [Robert L. Last, Whitehead Institute for Biomedical Research, Cambridge, MA 02142]