Assimilation and transport of fixed nitrogen in soybean nodule as revealed with 15N.

Using 15N tracer technique assimilation and transport of fixed nitrogen in the soybean nodule were studied in detail. Materials and methods. Nodules of the soybeans inoculated with Rhizobium japonicums and supplied with 15N2, were macerated and separated into various nitrogenous fractions, and subjected to the determination of total nitrogen or heavy nitrogen. In some experiments nodules were separated into the bacteroid and the cytosol fractions. Results and discussion. 1) Distribution of the fixed nitrogen in the nodule.1) Table I shows the abundance and distribution of 15N in 80% ethanolsoluble nitrogen of bacteroid and cytosol fractions separated immediately after exposure of 1JN2 gas to intact soybean nodules for 5 and 10 min. 15N abundance of both fractions at 10 min was approximately twice as high as those at 5 min,