An Electron Microscopic Study of DNA-like Fibrils in Chloroplasts

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For the purpose to examine whether or not the DNA-like fibril is the com-ponent common to chloroplasts, the electron microscopic observations were made on the cells of several species belonging to Rhodophyta, Phaeophyta, Chlorophyl a, Charophyta, Bryophyta, Pteridophyta, Gymnospermae and Angiospermae with special reference to the “DNA fibril complexes” which appear as dense structures in the electron-transparent regions of the chloroplasts. As the result, it has been demonstrated that the DNA fibril complexes are observable in the chloroplasts of the cells of several plants belonging to Rhodophyta, Phaeophyta, Chlorophyta, Charophyta and Bryophyta, and in the young cells of several plants belonging to Pteridophyta, Gymnospermae and Angiospermae without any exception, indicating that the DNA fibril complex would be a component of the chloroplasts widely distributed in lower plants as well as in higher plants.
In fully developed chloroplasts in older tissues of some vascular plants, namely, of Equiselum arzvense, Ginkgo biloba, Metasequoia glyfitostroboides, Spinacia oleracea and Zea mays, no DNA fibril complex is found in the electron-transparent regions.
DNA fibril complexes appear as fibrous structures with cloudy aggregates and core-like structures. Some differences in the morphological appearance of the complexes have been observed according to different species.