Interaction of lanthanum chloride with human erythrocyte membrane in relation to acetylcholinesterase activity.

Lanthanum chloride (1 mM) inhibits the activity of acetylcholinesterase in vitro in the human erythrocyte membrane. Lineweaver-Burk analysis indicates that lanthanum chloride induced inhibition of acetylcholinesterase activity is competitive in nature. The Arrhenius plot shows that the transition temperature of erythrocyte membrane-bound acetylcholinesterase is significantly reduced in the presence of lanthanum chloride. These results suggest that lanthanum chloride increases the fluidity of the erythrocyte membrane and this may be a cause of inhibition of membrane-bound acetylcholinesterase activity.

Evidence for the involvement of exposed surface carbohydrates of Agrobacterium tumefaciens in relation to crown gall tumour induction.

The exposed carbohydrate residues on the cell surface of both tumourigenic and nontumourigenic strains of Agrobacterium have been investigated using lectins as probes. N-acetyl-D-galactosamine and β-D-galactose were found to be present as the exposed groups on the cell surfaces of he Agrobacterium strains. These carbohydrate residues are attached to lipids on the outer membrane of the bacteria as lipopolysaccharides. Fluorescently labelled lectins were used to observe bacterial agglutination in fluorescence microscope. The involvement of these exposed carbohydrate groups in host-pathogen interaction was demonstrated by actual inhibition of tumour initiation at wound sites on host plant.