. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 26 H. TAMIYA et al. VOL. 12 (1953) RESULTS Characteristics of dark cells and light cells Stationary cultures grown under a moderate intensity of light usually show the dark cell ratio of to , the value being, as a rule, higher in weakly illuminated cultures than in strongly illuminated ones. By fractional centrifugation of these cultures we can obtain cell suspensions which consist practically entirely of dark cells or light cells. In Fig.
. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 26 H. TAMIYA et al. VOL. 12 (1953) RESULTS Characteristics of dark cells and light cells Stationary cultures grown under a moderate intensity of light usually show the dark cell ratio of to , the value being, as a rule, higher in weakly illuminated cultures than in strongly illuminated ones. By fractional centrifugation of these cultures we can obtain cell suspensions which consist practically entirely of dark cells or light cells. In Fig. 2 are shown the microphotographs of the two kinds of cells in such suspensions. Microscopic observation shows that the light cells may further be divided, according to the grade of ripening, into two categories, sporulated and non-sporulated, but they can hardly be separated by such a technique as fractional centrifugation. On the other. Fig. 2. Microphotographs of two types of cells at the same magnification. hand, the dark cells, in so far as they are defined by their cell diameters less than microns, appear under the microscope to be quite uniform in appearance. During the course of the present study, however, it was found that among dark cells there are also two distinct categories whicli can be obtained separately by a certain procedure. The one category, which we call "nascent dark cells" in tlK> following, consists of cells which represent the nascent state of dark cells derived from light cells. These cells can be obtained from light cells by incubating the latter in the dark while being well aerated. The other category, which we call "active dark cells", consists of dark cells derived from nascent dark cells by illuminating the latter for a few hours. Since the transformation in the light of the nascent dark cells into active dark cells takes place relatively rapidly, the dark cells contained in continuously illuminated cultures are mostly i
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