Incorporation of [3H]-Leucine into protein by animal tissues and by endosymbzotic chloroplasts in Elysia viridis montagu

Abstract

1. 1. Light microscopic and electron microscopic autoradiography have been used to study the incorporation of tritiated leucine into protein by the sacoglossan opisthobranch mollusc, Elysia viridis and its endosymbiotic chloroplasts acquired from the seaweed, Codium fragile. 2. 2. Light microscopic autoradioagraphy showed that several animal tissues incorporated [ 3H]-leucine into protein. Among these were the “secretory zones” of the digestive diverticulum, the testes and the pedal mucus gland. It is suggested that uptake of the metabolite was via the general integument. 3. 3. Electron microscopic autoradiography showed that protein in the chloroplasts becomes labelled after a 3-hr incubation, and the silver grain density over the chloroplasts does not change during a 1–12 hr “cold chase”. The possible sources of this protein are considered and evidence suggests that it is synthesized within the chloroplasts. 4. 4. Thus these chloroplasts have some degree of biochemical autonomy outside the algal cells.