Murine leukemia viruses: antigenic studies by quantitative complement fixation

The murine leukemia viruses of Rauscher and Friend, derived from plasnma of infected Balb/c mice, was purified. Their antigenic relationship was studied by quantitative complement-fixation reactions with the virion antigen and homologous antiserums. The complement-fixation curves observed in cross-reactions indicated close antigenic similarity between these two leukemia viruses. Highly purified viral preparations contained detectable amounts of host antigens.     

Crystal and molecular structure of acetylselenocholine iodide

The structure of acetylselenocholine iodide has been determined by x-ray crystallographic analysis. The molecule is in the trans conformation about the C-C bond of the choline residue. This conformation appears to explain the molecule's inability to give a positive cholinergic response when added to an electroplax preparation.     

Alpha-hydroxy acid oxidase: localization in renal microbodies

Differential and density equilibrium centrifugation have established the presence of alpha-hydroxy acid oxidase in microbodies of the kidney of the rat. The enzyme has been demonstrated in cells of the distal convoluted tubule by a microscopic cytochemical method. This enzyme, like certain others in microbodies, produces hydrogen peroxide.     

Molecular characterization of a functional cDNA encoding the rat substance P receptor

Substance P is a member of the tachykinin peptide family and participates in the regulation of diverse biological processes. The polymerase chain reaction and conventional library screening were used to isolate a complementary DNA (cDNA) encoding the rat substance P receptor from brain and submandibular gland. By homology analysis, this receptor belongs to the G protein-coupled receptor superfamily. The receptor cDNA was expressed in a mammalian cell line and the ligand binding properties of the encoded receptor were pharmacologically defined by Scatchard analysis and tachykinin peptide displacement as those of a substance P receptor. The distribution of the messenger RNA for this receptor is highest in urinary bladder, submandibular gland, striatum, and spinal cord, which is consistent with the known distribution of substance P receptor binding sites. Thus, this receptor appears to mediate the primary actions of substance P in various brain regions and peripheral tissues.     

Visual pigment density in single primate foveal cones

The feasibility is demonstrated of microspectrophotometric studies on primate photoreceptors aligned at right angles to the test beam, rather than axially illuminated. Pigment densities, and hence absorption per unit thickness, are approximately equal in primate rods and foveal cones. These pigment densities are similar to those reported for frog rods and fish cones.