08 December 1995
Vol 270, Issue 5242

About The Cover

MSL-2 is a male-specific protein in Drosophila that binds to hundreds of sites along the single male X chromosome and increases gene expression to match that of the two X chromosomes in females. When this protein is ectopically expressed in females, as shown in this immunofluorescence micrograph, the two X chromosomes (paired over most of their length) are decorated in a male-like pattern. See 1607. [Image: R. L. Kelley and M. I. Kuroda]