Phytotoxicity of colloidal solutions of metal-containing nanoparticles

Phytotoxicity of colloidal solutions of metal-containing nanoparticles (Ag, Cu, Fe, Zn, Mn) was investigated using a standard Allium cepa (L.) test system. Toxicity of experimental solutions at the organism level was evaluated in terms of biomass growth of onion roots, and cytotoxicity was estimated by proliferative activity of root meristem cells. The colloidal solutions of metal nanoparticles inhibited the growth of Allium cepa (L.) roots due to their ability to penetrate into cells and interact with their components and, thus, to inhibit mitosis. According to our results, cytotoxicity of test solutions decreases in the following order: Cu ≥ Zn ≥ Ag ≥ Fe. Solution of Mn-containing nanoparticles contributed to root growth reaction.     

Study of the receptor for black widow spider neurotoxin. I. Characteristics of membrane-bound and solubilized receptors from the bovine brain

Iodine-125 labelled alpha-latrotoxin from the venom of Central Asia black widow spider Latrodectus mactans tredecimguttatus binds specifically to the bovine brain membrane receptor producing a stable slowly dissociating complex with Kd = 1.6 x 10(-10) M and Bmax = 0.5 pmol/mg protein. Treatment of the complex with alkaline high-salt buffer induces reversible dissociation of the bound toxin. The antitoxin polyclonal antibody does not increase the dissociation rate of the bound toxin. Wheat germ lectin as well as concanavalin A inhibit the toxin binding to the membrane receptor. The receptor is solubilized with ionic and non-ionic detergents, and methods of latrotoxin binding assay are developed. The solubilized receptor is shown to retain high affinity to toxin, its binding activity being stable but critically dependent on the presence of calcium ions. Chromatographic properties of the receptor suggest its glycoprotein nature.     

Oxygen tension and water-soluble products of lipid peroxidation in blood of volunteers in hypobaric hyperoxia]

Oxygen tension in the arterial blood with transcutaneous method (tcPO2) and TBA-active products of venous blood plasma were measured during simulation of extravehicular activity. There was a parallel increase of tcPO2 and the level of TBA-active products upon introduction of hypobaric hyperoxia factor. Detrimental action of lipid peroxidation products on erythrocyte membranes can be one of the factors of anemia during space flight.