[Electron Microscope Radioautography of Glycine-(3)H Incorporation in the Petiolary Glands of Mercurialis Annua L]

Isolated young leaves of Mercurialis annua L. are successively fed with solutions of tritiated glycine and "cold" glycine. A radioautographic study of the cells of the petiolary glands shows sites of synthesis and translocation of proteins. Synthesis takes place in mitochondria, plastids, nucleus and ergastoplasm, including a very important part of the latter which contains big inclusions partly formed from proteins. Then, while mitochondria, plastids and nucleus remain radioactive, the newly formed proteins of the ergastoplasm successively pass to golgi bodies and smooth endoplasmic reticulum, to membranous whorls (myelin figures) and finally to external secretions. Since we know that golgi bodies contain polysaccharides, a role of these organelles might be to bind the newly formed proteins to these polysaccharides.