N-methyl-d-aspartate andl-aspartate activate distinct receptors in piriform cortex

The effects of ionophoretically applied N-methyl-DL-aspartate (NMDA) and aspartate on identified pyramidal neurons in rat piriform cortex were examined in isolated, submerged, and perfused brain slices. NMDA was more potent than aspartate in eliciting neuronal discharge. Perfusion of the acidic amino acid antagonists, DL-2-amino-5-phosphonovalerate (APV), 10(-6) or 10(-5) M, DL-2-amino-7-phosphonoheptanoate (APH), 10(-5) M, and gamma-D-glutamylglycine (gamma DGG), 10(-5) M, selectively blocked the response to NMDA without effect on the response to aspartate. At higher concentrations which blocked responses to both NMDA and aspartate, gamma DGG blocked kainate responses and depressed glutamate and quisqualate responses. These results suggest that in piriform neurons NMDA and aspartate act at distinct receptor sites, not a common receptor site, and that both of these sites are distinct from those that mediate responses to glutamate, quisqualate, and kainate.     

Purification and properties of Renilla reniformis luciferase.

Luciferase from the anthozoan coelenterate Renilla reniformis (Renilla luciferin:oxygen 2-oxidoreductase (decarboxylating), EC 1.13.12.5.) catalyzes the bioluminescent oxidation of Renilla luciferin producing light (lambdaB 480 nm, QB 5.5%), oxyluciferin, and CO2 (Hori, K., Wampler, J.E., Matthews, J.C., and Cormier, M.J. (1973), Biochemistry 12, 4463). Using a combination of ion-exchange, molecular-sieve, sulfhydryl-exchange, and affinity chromatography, luciferase has been purified, approximately 12 000-fold with 24% recovery, to homogeneity as judged by analysis with disc and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration, and ultracentrifugation. Renilla luciferase is active as a nearly spherical single polypeptide chain monomer of 3.5 X 10(4) daltons having a specific activity of 1.8 X 10(15) hp s-1 mg-1 and a turnover number of 111 mumol min-1 mumol-1 of enzyme. This enzyme has a high content of aromatic and hydrophobic amino acids such that it has an epsilon280nm 0.1% of 2.1 and an average hydrophobicity of 1200 cal residue-1. The high average hydrophobicity of luciferase, which places it among the more hydrophobic proteins reported, is believed to account, at least in part, for its tendency to self-associate forming inactive dimers and higher molecular weight species.     

Basic steroid saponins from aerial parts of Fritillaria Thunbergii

From the aerial parts of Fritillaria thunbergii, three glycosidal Solanum alkaloids (basic steroid saponins) were isolated together with minor     

Mechanism of Photoregulated Carotenogenesis in Rhodotorula minuta IV. Effect of Light on the Production of Ergosterol and Phytoene and on the Composition of Carotenoid Pigments

The effect of light on the production of ergosterol and phytoeneand on the composition of carotenoids in Rhodotorula minutawas studied to determine which part of the pathway of carotenoidsynthesis regulated by light. The ergosterol content in the cells was in the range of 3.4–3.6mg/g dry cells regardless of the presence or absence of illuminationand the light intensity. The phytoene production in the cellswas markedly stimulated by light and was dependent on the lightintensity according to the amount of carotenoid pigments produced.In addition, the ratio of phytoene to carotenoid was in therange of 0.36–0.44, regardless of the presence or absenceof illumination and the light intensity. The fact that the ratio of carotenoid fractionated on the basisof the functional group involved in each carotenoid to the totalamount of carotenoid was almost constant regardless of the lightintensity suggested that the composition of the carotenoidssynthesized in the cells is not affected by light. It was deduced from these results that light induced the productionof enzyme(s) required for phytoene biosynthesis in Rhodotorulaminuta. (Received November 7, 1981; Accepted March 19, 1982)     

Functional properties of the glycosylated minor hemoglobins A1a-1,A1a-2 and A1b. EPR evidence for increased stability of the low affinity quaternary structure and decreased susceptibility to organic phosphate

Electron paramagnetic resonance (EPR) spectra of the glycosylated minor hemoglobins A1a-1, A1a-2, A1b and A1c and the major hemoglobin A0 in the nitrosyl form have been obtained in the absence and presence of inositol hexaphosphate. In the absence of inositol hexaphosphate, nitrosyl hemoglobins A1a-1, A1a-2 and A1b exhibited a triplet hyperfine structure centered at g = 2.009 which has been shown to be diagnostic of the low affinity (T) quaternary structure. Addition of inositol hexaphosphate to nitrosyl hemoglobins A0, A1c, A1b and A1a-2 developed a triplet hyperfine structure of the EPR spectra but the magnitude of the hyperfine was decreased in the order of hemoglobins A0, A1c, A1b and A1a-2. However, inositol hexaphosphate had essentially no effect on the EPR spectrum of nitrosyl hemoglobin A1a-1. The present results account qualitatively for the oxygen binding properties of these glycosylated minor hemoglobins in the framework of a two-state allosteric model.     

Determination of serum unconjugated estrone, estradiol-17β and estriol during pregnancy by selected ion monitoring

A simple, rapid and highly specific method by selected ion monitoring (SIM), using 9α,11α-[²H₂]estrone, [2,4-²H₂]estradiol-17β and 2,4-[²H₂]estriol as internal standards, was developed for the determination of serum estrogens during pregnancy. Serum samples were submitted to a simple extraction procedure and were analysed after formation of the trifluoroacetic anhydride derivative. The inter-assay coefficients of variation for estrone, estradiol-17β and estriol were 3.73%, 3.42% and 3.49%, respectively. The results obtained by SIM were compared with analysis performed using radioimmunoassay.     

Metabolism of urea in Chlorella ellipsoidea

The effect of cyanide on ammonia and urea metabolism was studiedwith intact cells of Chlorella ellipsoidea Gerneck, a greenalga which apparently lacks urease. Ammonia uptake was inhibited more readily by cyanide than wasurea uptake. Urea uptake was stimulated by lower concentrationsof cyanide. The addition of cyanide caused the formation ofammonia from some cellular nitrogenous compounds. In the presenceof exogenously added urea, the molar ratio of ammonia accumulatedin the medium to urea taken up exceeded 2.0 as the cyanide concentrationincreased. However, the molar ratio of ammonia actually producedfrom urea nitrogen to urea taken up was less than 1.35 at anyconcentration of cyanide tested. In the presence of higher concentrationsof cyanide, the rate of incorporation of ¹⁵N into amino acidsfrom ¹⁵N-urea was higher than that from ¹⁵N-ammonium sulfate. The results suggest that Chlorella ellipsoidea possesses a pathwaythrough which urea nitrogen is assimilated directly withouta preliminary breakdown to ammonia. (Received October 18, 1976; )     

Evolution of ribosomal proteins in Enterobacteriaceae.

The evolution of ribosomal proteins of about 70 bacterial strains belonging to the family Enterobacteriaceae has been studied by use of previously reported data (S. Osawa, T. Itoh, and E. Otaka, J. Bacteriol. 107:168-178, 1971) and those obtained in this paper. The proximity of the bacteria was quantified by co-chromatographing the differentially labeled ribosomal proteins from two strains on a column of carboxymethyl cellulose in various combinations. The were then classified into 12 groups (=species?) according to their ribosomal protein compositions and were placed in a phylogenic tree.