EVIDENCE FOR THE EXISTENCE OF TWO TYPES OF NUCLEOLAR RIBONUCLEOPROTEIN IN ROOT MERISTEMATIC CELLS OF VICIA FABA

Abstract

In Helly-fixed root meristematic cells of Viciafaba, the toluidine blue – molybdate staining procedure reveals the existence within the interphase nucleus of two metachromatically distinct types of nucleolar ribonucleoprotein. The ribonucleoprotein of the first type stains bluish-green and is associated with the nucleolar matrix. The ribonucleoprotein of the second type takes on a bright purple color and is present inside the nucleolar vacuoles. Evidence is presented suggesting that, during interphase, the nucleolus is the site of active synthesis and of accumulation inside its vacuoles of the second type of ribonucleoprotein.