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Reversible Dark-Induced Senescence Of Soybean Root Nodules, N. E. Pfeiffer, Nasir S.A. Malik, Fred W. Wagner
Reversible Dark-Induced Senescence Of Soybean Root Nodules, N. E. Pfeiffer, Nasir S.A. Malik, Fred W. Wagner
Department of Biochemistry: Faculty Publications
Nodule senescence was induced in intact soybean Glycine max. (L.) Merr., cv Woodworth plants by an 8-day dark treatment. Dark-induced senescence resulted in the complete loss of acetylene reduction activity, a 67% loss of total soluble protein, and an almost complete loss in total leghemoglobin of nodule extracts. Isoelectric focusing gels demonstrated a preferential loss of certain proteins, which was correlated with an increase in endoprotease specific activity toward azocasein. Nodules were completely green after the 8-day dark treatment. If plants were returned to a normal photoperiod after 8 days in the dark, nodules recovered from the dark treatment in …
Proteolytic Activity In Soybean Root Nodules: Activity In Host Cell Cytosol And Bacteroids Throughout Physiological Development And Senescence, Nancy E. Pfeiffer, Cecilia M. Torres, Fred W. Wagner
Proteolytic Activity In Soybean Root Nodules: Activity In Host Cell Cytosol And Bacteroids Throughout Physiological Development And Senescence, Nancy E. Pfeiffer, Cecilia M. Torres, Fred W. Wagner
Department of Biochemistry: Faculty Publications
Root nodules were harvested from chamber-grown soybean (Glycine max L. Merril cv Woodworth) plants throughout development. Apparent nitrogenase activity (acetylene reduction) peaked before seeds began to develop, but a significant amount of activity remained as the seeds matured. Nodule senescence was defined as the period in which residual nitrogenase activity was lost. During this time, soluble protein and leghemoglobin levels in the host cell cytosol decreased, and proteolytic activity against azocasein increased. Degradative changes were not detected in bacteroids during nodule senescence. Total soluble bacteroid protein per gram of nodule remained constant, and an increase in proteolytic activity in …
Nickel: A Micronutrient Element For Hydrogen-Dependent Growth Of Rhizobium Japonicum And For Expression Of Urease Activity In Soybean Leaves, Robert V. Klucas, F. Joe Hanus, Sterling A. Russell, Harold J. Evans
Nickel: A Micronutrient Element For Hydrogen-Dependent Growth Of Rhizobium Japonicum And For Expression Of Urease Activity In Soybean Leaves, Robert V. Klucas, F. Joe Hanus, Sterling A. Russell, Harold J. Evans
Department of Biochemistry: Faculty Publications
Soybean plants and Rhizobium japonicum 122 DES, a hydrogen uptake-positive strain, were cultured in media purified to remove Ni. Supplemental Ni had no significant effect on the dry matter or total N content of plants. However, the addition of Ni to both nitrate-grown and symbiotically grown plants resulted in a 7- to 10-fold increase in urease activity (urea amidohydrolase, EC 3.5.1.5) in leaves and significantly increased the hydrogenase activity (EC 1.18.3.1) in isolated nodule bacteroids. When cultured under chemolithotrophic conditions, free-living R. japonicum required Ni for growth and for the expression of hydrogenase activity. Hydrogenase activity was minimal or not …