Effect of Salt Stress on Nitrogen Assimilation of Functional Leaves and Root System of Rice in Cold Region

The aims were to investigate the effect of salt stress on key enzyme activity of nitrogen metabolism and the concentration of nitrate nitrogen and ammonium nitrogen response to salt stress.Two rice cultivars,Mudanjiang 30(sensitive cultivar)and Longdao 5(salt-tolerant cultivar),were treated with different salt concentrations(CK 0%,S10.075%,S20.15%,S30.225%and S40.3%).The results showed that the activities of nitrate reductase(NR),glutamine synthase(GS),glutamate synthase(GOGAT)and glutamate dehydrogenase(GDH)in the functional leaves and roots of rice in cold region presented a single peak curve change and the peak occurred in the heading stage;compared with those of the CK,the activities of NR,GS and GOGAT of rice in cold region decreased,but the activity of GDH increased in the heading stage under salt stress.The variation for key enzyme activity of nitrogen metabolism was the highest under S4 treatment.The activities of NR,GS and GOGAT in the functional leaves significantly decreased compared with those in roots;the concentrations of nitrate nitrogen and ammonium nitrogen in the functional leaves and roots of rice in cold region presented a single peak curve change and the peak occurred in the heading stage;compared with that of the CK,the concentration of nitrate nitrogen decreased in leaves and roots,the concentration of ammonium nitrogen decreased and the concentration of ammonium nitrogen in roots increased under salt stress.The variations for the activities of NR,GS and GOGAT in the functional leaves and roots of Longdao 5 were less than those of Mudanjiang 30 under the same concentration of salt stress.

Influence of Flavonoid of Astragalus membranaceus′s Stem and Leaves on the Function of Cell Mediated Im munity in Mice

Objective: To investigate the immune regulation of flavonoid of Astragalus membranaceus′ s stem and leaves (FAM). Methods: Changes of total T cell count and subsets in mice were determined by monoclonal antibody assay before and after treatment with FAM, and the lymphokine activated killer(LAK) activity was tested simultaneously by isotope technique. Results: FAM could promote the proliferation of lymphocytes induced by ConA, raise the T cell count and regulate the T cell subsets disorder, elevate the LAK activity induced by IL 2. Conclusion: FAM possesses the effect of immune stimulation and immune regulation in treating immunosuppressive mice. This study provides the experimental basis for clinical application of FAM.