Carbon isotope fractionation by structurally and catalytically distinct ribulose-1,5-bisphosphate carboxylases from one eucaryotic and four procaryotic organisms has been measured under nitrogen. The average fractionation for 40 experiments was -34.1 per thousand with respect to the delta(13)C of the dissolved CO(2) used, although average fractionations for each enzyme varied slightly: spinach ...

A technique for measurement of the stable isotope composition of dissolved organic carbon (DOC) in stream water, using an elemental analyzer (EA) coupled to an isotope ratio mass spectrometer (IRMS), is described. Stream water samples were concentrated by rotary evaporation, acidified to remove dissolved inorganic carbon (DIC), and dried in silver cups prior to analysis. Precision was evaluated...

The seasonal changes of leaf physiological traits and its relationship with abiotic factors (photosynthetic active radiation-PAR, leaf temperature-Tleaf, air temperature-Tair, Tleaf - Tair- ΔT) were studied on sugar beets grown under the semi-arid conditions of central Greece. Sugar beet (Beta vulgaris L.) cv Rizor was established in a Randomised Complete Block design experiment for two years (...

Keeley, J.E., Sternberg, L.O. and DeNiro, M.J., 1986. The use of stable isotopes in the study of photosynthesis in aquatic plants. Aquat. Bot., 26:213--223. The ratio of ~3C/'2C for photosynthetic tissues of 22 aquatic species was unrelated to photosynthetic pathway. In three aquatic environments CAM and non-CAM species were shown to have similar 513C values. Although these CAM species derive u...

In this scheme, the racemase involves a rearrangement of the hydrogen about the asymmetrical carbon (6,7), while the mutase reaction involves an intramolecular migration (8, 9) of the thioester group (l&12). Two approaches are available to determine the source of the hydrogen that arises on carbon 3 of succinyl-CoA as a result of methylmalonyl-Coil mutase action. The first or indirect approach,...