Separating the Influx and Efflux Components of Net Uptake of NO3- and NH4+ with the Use of Isotopic Fractional Data: Final Report, July 15, 1987-July 14, 1989.

摘要

Transport processes are central to the life of organisms. It is important to dissect net uptake of metabolites and evaluate its components (influx and efflux). Results of our study have shown that our method, based on isotopic fractionation is successful in separating the impact of changes in influx vs efflux on changes in net uptake of nitrate and that there is a high probability that the method will be equally successful with ammonium uptake. The methodology is applicable to steady state conditions unlike previous methods which involve the use of (15)N or (13)N labeled material or (14)C labeled analogs. These previous methods require short term measurements, the shorter, the more accurate. The isotopic fractionation methodology will be applicable to steady state experiments with other nutrients containing atoms whose stable isotope abundance is measurable at the level of precision necessary for determination of overall isotopic fractionation factors (e.g., C(prime), N, O, S). 33 refs., 3 figs., 2 tabs.