Experiments on the Application of Autoradiographic Techniques to the Study of Problems in Plant Physiology

Abstract

A method of autoradiography has been developed which allows the record of single ,a-particles emitted from sections of plant tissue 5-7 ~L thick. The method allows resolution of the order of 1 ~ and magnification up to x 1500. Dissolution of the water and alcohol soluble contents of the tissue has been overcome, and it is therefore possible to determine the distribution of compounds concerned in the metabolism and biosynthesis of a cell. Cellular distortion and loss of contents during fixation and photographic processing is illustrated, and it is hoped that an improved method of freeze-drying· will reduce this limitation. In macroscopic autoradiography the soya bean has proved to be most valuable plant material, because the thin stems and leaves allow autographs which give a detailed record of the transported compounds containing 14C. The isotope is introduced to the plant in the photosynthesis of 14C02, and after a suitable period, the plant is dissected, dried, and placed against X-ray film. After 14 days exposure the film is developed, and the photographic image records positions and relative concentration of the isotope in the plant tissue.