Behavioral plasticity in aDrosophila mutant,dunce DE276

Summary Drosophila X-linked mutantdunce ^DB276 fails to display learning in an olfactory learning paradigm, in spite of being able to sense odorants and shock (Byers, 1977; Fig. 1). However, conditions exist under which the flies display associative behavior (Table 1, Figs. 3, 5). Memory appears to be short-lived (Table 1, Figs. 3, 5) and labile (Figs. 3, 4). It is suggested that thedunce ^DB276 mutation affects an early memory phase.I thank G. Bicker, D. Byers and W.G. Quinn for valuable comments. This work was supported by a grant from the United States-Israel Binational Science Foundation, Jerusalem. The author is incumbent of the Barecha Foundation Career Development Chair.     

Multiple Defects in the Activity of Adenylate Cyclase from the Drosophila Memory Mutant Rutabaga

Adenylate cyclase in homogenates of Drosophila melanogaster is heterogeneous with respect to its affinity toward MgATP and its subcellular distribution. Km values for MgATP range, under similar assay conditions, from approximately 10(-5) M to approximately 10(-3) M, depending on the body region and on the subcellular localization of the enzyme. The majority of the enzyme in whole-body preparations is particulate, but various body regions differ in the relative proportion of the soluble enzyme. The memory mutant rutabaga lacks up to 35% of the total particulate activity. Even ligands that stimulate directly the catalytic subunit are incapable of bringing the activity of the mutant's enzyme to normal levels. The defect is differentially pronounced in various body parts and is associated with an altered responsiveness of the enzyme to Mg2+, to Ca2+, and to forskolin. It is suggested that rutabaga is lesioned in a subpopulation, or a functional state, of adenylate cyclase, which may play a role in memory formation.     

Heterogeneity in the physicochemical properties of deoxycholate-solubilized benzodiazepine receptors from calf cerebral cortex

The hydrodynamic behaviour of benzodiazepine receptors solubilized by deoxycholate from calf cerebral cortex reveals two molecular forms. The Stokes radii are 46.5 A and 67.2 A, and the sedimentation coefficients are 10.9 S and 14.6 S. The calculated apparent molecular weights and frictional ratios suggest either two nearly globular proteins of ca. 200K and 400K daltons each, or two ca. 300K daltons proteins which differ significantly in their degree of asymmetry. The benzodiazepine binding site is located on ca. 51K daltons component(s) in both forms.