19 January 1990
Vol 247, Issue 4940

About The Cover

Immunological staining of individual Mycoplasma hyorhinis colonies with a monoclonal antibody to a surface lipoprotein antigenic variant. High-frequency switching in the expression of this component is reflected in the heterogeneous staining and sectoring of colonies representing clonally derived populations of this organism. See page 315. [Photomicrograph by Renate Rosengarten and Kim S. Wise, Department of Molecular Microbiology and Immunology, University of Missouri—Columbia, Columbia, MO 65212]