| Popis: |
Cells of Euglena gracilis var. bacillaris, obtained by culturing the organism in Hutner's sugar-containing medium (pH 3.5) whitout agitation in darkness, were rich in wax as well as in paramylum. When these cells were transferred to an inorganic medium (pH 6.8) and aerated with 2% (v/v)CO 2 in air in darkness, the lipid (wax) markedly decreased with a concomitant decrease in the O 2 -uptake activity of the cells. Fluoroacetate (5x10 −4 M) suppressed the decrease of lipid. The dark-grown wax-rich cells contained extremely degenerated proplastids with the girdle thylakoid located close to the envelope. These proplastids expanded, and prolamellar bodies and some prothylakoids were formed within 72 hr after transfer to the inorganic medium in the dark with aeration. Fluoroacetate (5x10 −4 M), antimycin A (10 μg/ml), and 2,4-dinitrophenol (10 −3 M) suppressed the expansion of proplastids and the concomitant development of structure. It was inferred that oxidative metabolism of wax provides materials and energy for the dark development of proplastids in dark-grown Euglena cells transferred to the inorganic medium. When these dark-incubated cells were exposed to light, a large amount of paramylum was degraded concomitant with the formation of chlorophyll and chloroplast thylakoids. The roles of oxigen, light, and a nitrogen source (ammonium ions) in the metabolism of wax and paramylum to provide materials and energy for the development of proplastids are discussed |
