Chloroplasts were isolated from the marine alga Codium vermilara (Siphonales). The isolated chloroplasts were active in CO(2) fixation in the light at a rate comparable to the rates obtained by fragments of thalli. Maximal rates of CO(2) fixation by isolated chloroplasts from Codium were obtained in the presence of salt or sorbitol isoosmotic with sea water. The conditions of isolation of Codiu...

Externally added quercetin (100 micromolar) was oxidized by intact spinach chloroplasts at a rate of 30 micromoles per mg chlorophyll per hour in the presence of 100 micromolar H(2)O(2). The oxidation rate was increased by about 20% in a hypotonic reaction mixture. The thylakoid fraction also oxidized the flavonol in the presence of H(2)O(2), and the rate was about 25% of that by intact chlorop...

In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, whereas bundle sheath chloroplasts are located in either a centripetal or centrifugal position. It was reported previously that only M chloroplasts aggregatively redistribute to the bundle sheath side in response to extremely strong light or environmental stresses. The aggregative movement of M chloroplast...

Chloroplasts of higher plants have been isolated from leaf homogenates, with greater or lesser attempts at purification from other types of particles, using differential centrifugation. Such preparations of chloroplasts, or "chloroplastic matter" (see earlier reviews, 27, 36), have in some cases been reported to contain a series of components; for instance nucleic acid (10, 15, 26), catalase (2...

In C(4) plants, bundle sheath (BS) chloroplasts are arranged in the centripetal position or in the centrifugal position, although mesophyll (M) chloroplasts are evenly distributed along cell membranes. To examine the molecular mechanism for the intracellular disposition of these chloroplasts, we observed the distribution of actin filaments in BS and M cells of the C(4) plants finger millet (Ele...

Photosynthesis, Fluorescence Lifetimes, Aging, Sonicated Chloroplasts The lifetime of fluorescence from pea chloroplasts at room temperature increases with age. The ratio of the fluorescence intensities of the slow to fast decay components, decreases with age of the chloroplasts. This observation can account for the wide range of lifetimes reported in the literature. The variability of biologic...

Although cytokinins (CKs) affect a number of processes connected with chloroplasts, it has never been rigorously proven that chloroplasts contain CKs. We isolated intact chloroplasts from tobacco (Nicotiana tabacum L. cv SR1) and wheat (Triticum aestivum L. cv Ritmo) leaves and determined their CKs by liquid chromatography/tandem mass spectroscopy. Chloroplasts from both species contained a who...

A new approach to measurements of photosynthesis by isolated chloroplasts has been devised. Intact isolated chloroplasts were trapped in the cavities of membrane filters. The thin layers of chloroplasts so obtained were assayed for O(2) evolution and CO(2) assimilation in leaf-chambers. Photosynthetic gas exchange could be demonstrated to take place either in a closed or a flow-through system. ...

Chloroplasts regulate their growth to optimize photosynthesis. Quantitative data show that the ratio of total chloroplast area to mesophyll cell area is constant across different cells within a single species and also across species. Wild-type chloroplasts exhibit little scatter around this trend; highly irregularly shaped mutant chloroplasts exhibit more scatter. Here we propose a model motiva...

Histone inhibits the photosystem 1 activities of isolated chloroplasts. This inhibition can be prevented by prior exposure of the chloroplasts to moderate concentrations of inorganic salts. However, even very high concentrations of inorganic salts will not reverse the inhibition, nor is the inhibition reversed by washing the chloroplasts. Exogenous plastocyanin causes a partial reversal of hist...