The marine gastropod molluscs Tridachia crispata, Tridachiella diomedea, and Placobranchus ianthobapsus (Sacoglossa, Opisthobranchia) possess free functional chloroplasts within the cells of the digestive diverticula, as determined by observations on ultrastructure, pigment analyses, and experiments on photosynthetic capacity. In the light, the chloroplasts incorporate H(14)CO(3) (-)in situ. Re...

The existence of DNA-containing regions in chloroplasts and mitochondria of plants of varying systematic relationship and developmental stage has been sufficiently proved by electron microscopy (1, 2). So far, however, no study of the exact spatial distribution or of the variation in size and number of these regions per organelle has appeared, even for the more simply constructed chloroplast of...

Chloroplasts, or photosynthetic plastids, multiply by binary fission, forming a homogeneous population in plant cells. In Arabidopsis thaliana, the division apparatus (or division ring) of mesophyll chloroplasts includes an inner envelope transmembrane protein ARC6, a cytoplasmic dynamin-related protein ARC5 (DRP5B), and members of the FtsZ1 and FtsZ2 families of proteins, which co-assemble in ...

We identified an Arabidopsis thaliana mutant, clumped chloroplasts 1 (clmp1), in which disruption of a gene of unknown function causes chloroplasts to cluster instead of being distributed throughout the cytoplasm. The phenotype affects chloroplasts and nongreen plastids in multiple organs and cell types, but is detectable only at certain developmental stages. In young leaf petioles of clmp1, wh...

The kinetics of the 520 mmu absorption change in spinach chloroplasts and Chlorella vulgaris following a flash from the ruby laser have been determined as follows: rise halftime </= 0.3 x 10(-6) second; rapid recovery halftime = 5 to 6 x 10(-6) second; intermediate recovery halftime = 4 x 10(-4) second (spinach chloroplasts only); slow recovery halftime = 12 to 170 x 10(-3) second, dependent on...

Isolated spinach chloroplasts purified by isopycnic centrifugation in density gradients of Percoll were found to be highly intact, to be devoid of extrachloroplastic contaminations, and to retain a high rate of CO(2)-dependent O(2) evolution.When suspended in a medium which avoided rupture of the envelope, intact purified chloroplasts progressively lost their phosphate content by passive diffus...

Bicarbonate uptake by isolated chloroplast envelope membranes and intact chloroplasts of spinach (Spinacia oleracea L. var. Viroflay) in darkness exhibited a similar dependency upon temperature, pH, time, and concentrations of isolated or attached envelope membranes. This similarity in uptake properties demonstrates the usefulness of the envelope membranes for the study of chloroplast permeabil...

Bicarbonate ion, not dissolved CO(2) gas, is shown to increase 4- to 5-fold the rate of dichlorophenol indophenol reduction by isolated maize (Zea mays) chloroplasts. Glutaraldehyde fixed chloroplasts continue to exhibit bicarbonate-dependent 2,6-dichlorophenol indophenol reduction. Bicarbonate is shown to act close to the oxygen-evolving site, i.e. prior to the electron donation site of diphen...

1. Enzyme distribution between chloroplasts and the nonchloroplast parts of green leaf cells of Spinacia oleracea, Nicotiana rustica, Vicia faba, and Phaseolus vulgaris have been investigated by use of the nonaqueous chloroplast isolation technique. Whereas pyruvate kinase and peroxidase were located only or mainly outside of the chloroplasts, the other enzymes studied, isocitric dehydro­ genas...

High rates of both cyclic and noncyclic photophosphorylation were measured in chloroplast lamellae isolated from purified guard cell protoplasts from Vicia faba L. Typical rates of light-dependent incorporation of (32)P into ATP were 100 and 190 micromoles ATP per milligram chlorophyll per hour for noncyclic (water to ferricyanide) and cyclic (phenazine methosulfate) photophosphorylation, respe...