Photosynthetic Assimilation of Carbon Dioxide and Acetate by Isolated Chloroplasts

Abstract

Chloroplasts isolated by methods similar to that described by Arnon et al. (1) are capable of incorporating acetate carbon into both lipid and n)on-lipid materials when fortified with appropriate cofactors (2,3,4,5 (table I). Air inhibited the rate of photosynthesis by about 25 % in the presence and absence of acetate but had no effect on the distribution of 14C assimilated. Furthermore, we found that the presence of 1 mM acetate did not affect either the uptake of 1"CO, or

Changes in Fine Structure of Prolamellar Body in Relation to the Formation of the Chloroplast

“…According to K. Muhlethaler and Frey-Wyssling (1959)11', the formation of a prolamellar body occurs, as a rule, in etiolated plants, but not in plants grown under sufficient light. Gunning (1967)9', R. G. Everson (1967)13', and M. Wrischer (1966)14' have also made similar observations that the vesicles of a crystalline prolamellar body are gradually dissociated and the double lamellae come into appearance in the light. As a rule, one or two prolamellar bodies were observed in these plastids.…”

Amino Acid Biosynthesis by Isolated Chloroplasts during Photosynthesis

“…The recorded rates of photoreduction of 2-ketoglutarate by isolated chloroplasts are 0.4 ,umole/mg chl-hr (spinach [35]) and 0.6 ,umole/mg chl-hr (broad bean [11]). These low rates may partly account for the finding that, although chloroplasts can now be prepared which are capable of photosynthetic CO2 fixation at rates comparable with those observed in vivo (7,17,18), in general only 5 to 10% of the total radioactivity is recovered in the amino acid fraction (9,37). In isolated chloroplast suspensions aspartate (37), aspartate and alanine (9, 25), and glycine and serine (8) have been shown to be among the products of photosynthetic "CO2 fixation.…”

The synthesis of fatty acids in avocado mesocarp and cauliflower bud tissue

“…From the above and from numerous other reports it might be concluded that fatty acid biosynthesis occurs in plants in at least three different subcellular locations. In photosynthetic tissues, isolated chloroplasts have been found to incorporate acetate into fatty acids, although whether preparations actively fixing CO2 do this has been disputed (Everson & Gibbs, 1967;Boardman & Stumpf, 1970). Preparations described as mitochondrial have been found to form saturated, and to a much smaller extent unsaturated, fatty acids from acetate and acetyl-CoA, but the respiratory activities of these preparations have not been described in detail.…”