Use of the scanning electron microscope in the study of isssolated ribosomes and polysomes

A procedure is described by which the ribosome assemblies isolated from the buds of Scots pine ( Pinus sylvestris L.) as well as the ribosome and polysome fractions purified by sucrose density gradient centrifagation can be prepared for study by scanning electron microscopy. The technique has also been used to illustrate ribosomes extracted froai leaves and roots of Nicotiana tabacum L., from roots of Tuiipa gesneriana hybr. and from commercial wheat germ. The sample under study is spread on a piece of coverslip', frozen and dried at room temperature. The coverslip, with attached material, is taken through the critical point drying procedure, glued on a specimen retainer aod coated with gold-palladium. The coverslip serves as a sufficiently stable specimen support to allow the study of ribosomes at magnifications of several hundred thousand. Use of the method makes it possible to study the structure of polysomes, to check the purity of fractioned samples and to investigate differences in the ribosome assembly of the developing plant tissues.