Contents

07 July 2000
Vol 289, Issue 5476

About The Cover

Cover image expansion

COVER In 1951, Barbara McClintock described mobile genetic elements, now called transposons, that could move from place to place in the chromosomes of maize, producing the variegated pigmentation of kernels (background). The x-ray structure of the key enzyme transposase (orange and yellow), which mediates transpositions such as these, is shown in complex with the two ends of a DNA transposable element (purple). See page 77.
[IMAGE: H. A. STEINBERG, D. R. DAVIES, I. RAYMENT; B. MCCLINTOCK, COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 16, 13 (1951), USED WITH PERMISSION FROM COLD SPRING HARBOR LABORATORY PRESS]