Ultrastructural and biochemical studies on ribonucleoprotein particles from isolated nucleoli of thioacetamide-treated rat liver

The morphology of isolated nucleolar ribonucleoprotein particles from thioacetamide-treated rat livers was found to be very similar to those in situ. The sedimentation profiles of these nucleolar ribonucleoprotein particles in sucrose density gradients showed the presence of three components. The particles in these peaks were electron opaque spherical particles that were quite homogeneous in size (200–250 Å). The ultrastructure of these RNP particles from thioacetamide-treated livers is similar to that of both ribosomes and intranucleolar RNP particles inasmuch as at high magnifications a convoluted, linear strand of RNA was observed to be present in each of the particles.