Processes of 35S-labelled sulfite uptake and efflux by oat protoplasts and their chloroplasts are very rapid: during the first minutes (or perhaps even seconds) after sulfite supply a state of equilibrium is established between the protoplasts and their chloroplasts and the incubation medium. Bicarbonate concentrations ranging from 1 to 5 mᴍ in the medium had no significant effect on sulfite uptake. At pH 7.0 sulfite uptake is much greater than at pH 7.6. Light of low intensity (9 W m-2) had no significant effect on this uptake. The 35S concentration in chloroplasts was always much higher than in the whole protoplasts. One hour's incubation at sulfite concentra tions of 0.1 and 0.5 mᴍ in the medium, concentrations slightly stimulating or inhibiting photosyn thesis, results in sulfite concentrations of 0.004 to 0.230 mᴍ in chloroplasts. At a sulfite concentration photosynthesis, these values are 0.120 to 0.551 and 2.045 to 3.531, respectively.
A Journal of Biosciences: Zeitschrift für Naturforschung C (ZNC) is an international scientific journal for the emerging field of natural and natural-like products. ZNC publishes original research on the isolation, bio-chemical synthesis and bioactivities of natural products, their biochemistry, pharmacology, biotechnology, and biological activity and innovative developed computational methods for predicting their structure and/or function.