Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: -pumping + H activities of plasma membrane and tonoplast from Quercus rubra roots. | 684s Ann. Sci. For. 1989 46 suppl. 684S-689S Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA H -pumping activities of plasma membrane and tonoplast from Quercus rubra roots A. Lamant R. Devilder and p. Seillac Laboratoire de Biologie et Physiologie Végétales CNRS URA45 Université de Bordeaux I av. des Facultes 33405 Talence Cedex France Introduction Climatic conditions in France are favorable for red oak Quercus rubra which is being used increasingly in afforestation. But edaphic restriction calcifuge property nitrogen nutrition low level of NOj accumulation and sensitivity to high pH suggested a contribution of membranes plasmalemma and tonoplast to these physiological properties. Herein we present the first results concerning in vitro identification of these membranes. Two membrane fractions were collected from Ơ g-crrr3 and Ở g-cm-3 steps of sucrose density gradients from 12 000-130 000 X g pellets. An aqueous 2 polymer phase system was used to obtain a better purification. The plasma membranes were identified in the high density fraction by the APTc phosphotungstic acid-CrO3 stain associated with vanadate-sensitive Mg2 ATPase Mg2 adenosine triphosphatase pH . Tonoplast was characterized in the low density fraction by its negative reaction to APTc the nitrate-sensitive Mg2 ATPase pH 8 and the presence of a PPase pyrophosphatase . ATP induces quenching of ACMA 9-amino-6-chloro-3-methoxy-acridine fluorescence in both fractions and requires Mg2 the quenching is collapsed by NH and nigericin. The initial rates of quenching 600-700 quenching-mg-1 prot-min-1 for plasmalemma and 500 for tonoplast indicate very good coupling between hydrolytic and pumping activities but the Km were different. Materials and Methods Plant material Roots were excised from young plants 3 wk and chilled in cold aerated grinding medium. Membrane isolation 50 g fresh weight of roots were homogenized in 150 ml of a grinding medium containing M sucrose 25 mM .
