Photosynthesis by Intact Isolated Chloroplasts on Solid Support

Abstract

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 02 evolution and CO2 assimilation in leafchambers. Photosynthetic gas exchange could be demonstrated to take place either in a closed or a flow-through system. The chloroplasts were morphologically intact as shown by light or sanning electron microscopy and displayed stable rates of photosynthesis in the presence of phosphate and alkaline phosphatase. Here we shall describe attempts we have made to trap CSS', in order to be able to investigate their function under conditions more closely resembling those in leaves. In this way, the ratio of chloroplasts to suspending medium could be increased 100-fold.In the past, several attempts have been made to immobilize chloroplasts for the purpose of stabilization, but these attempts were restricted, with one exception (7), to the preservation and measurements of electron transport, with complete loss ofcapacity for carbon assimilation (1,(8)(9)(10)12). In the present work, intact CSS assimilated CO2 and evolved 02. Gas exchange meas-

A re-investigation of the path of carbon in photosynthesis utilizing GC/MS methodology. Unequivocal verification of the participation of octulose phosphates in the pathway

“…Methods for the preparation of chloroplasts for use in the leaf-disc oxygen electrode were based on those previously described (Cerovic et al. 1987). Chloroplasts were mounted on a filter membrane by filtering a suspension of chloroplasts through a cellulose nitrate membrane (Sartorius, 50 mm diameter, pore size 8 μm).…”

The use of chlorophyll fluorescence excitation spectra for the non‐destructive in situ assessment of UV‐absorbing compounds in leaves

“…Isolated chloroplasts from young spinach and pea leaves were prepared according to (Cerovic & Plesnicar 1984), and trapped on cellulose filters (SM11301; Sartorius, Göttingen, Germany) as described in (Cerovic, Cheesbrough & Walker 1987). Chlorophyll concentration of chloroplast solutions and chloroplasts on solid support (CSS) was determined according to (Bruinsma 1961).…”

Simultaneous measurement of changes in red and blue fluorescence in illuminated isolated chloroplasts and leaf pieces: The contribution of NADPH to the blue fluorescence signal

“…Wobli) acquired at the local market, were illuminated for 30min with white light (PPFD = 800 /.~mol m -2 s -1) in cool water. Intact isolated chloroplast were prepared as in Cerovic et al (1987). The preparations were 80 to 85% intact as judged by ferricyanide penetration (Walker et al 1986) with maximal rates of CO2-dependent Ot evolution not exceeding 25mmol O2mol Chls -1.…”