Characterization by [3H]Dihydroergocryptine Binding of Alpha-Adrenergic Receptors in Neuroblastoma × Glioma Hybrid Cells

[3H]Dihydroergocryptine ([3H]DHE) was shown to bind to sites in membranes from neuroblastoma X glioma hybrid cells (NG 108-15) that had the characteristics expected of alpha-adrenergic receptors. The binding was saturable with 0.3 pmol [3H]DHE bound per mg of protein and of high affinity, with an apparent dissociation constant (KD) of 1.8 nM. The specificity of the binding site for various ligands was more similar to that of alpha 2 receptors than to that of alpha 1. No specific binding of [3H]WB-4101 was found in the membranes derived from NG 108 cells. This finding also indicated that the [3H]DHE binding site in the cell is the alpha 2 receptor. GTP lowered the affinity of agonists for the [3H]DHE binding site, although the nucleotide hardly affected the affinity of antagonists including [3H]DHE.     

Induction of 3-Hydroxy-3-methylglutaryl CoA Reductase in Potato Tubers after Slicing, Fungal Infection or Chemical Treatment, and Some Properties of the Enzyme

Intact tubers of potato (Solanum tuberosum L. cv. Irish Cobblerand an interspecific hybrid between S. tuberosum and S. demissumcv. Rishiri) contain a very low activity of 3-hydroxy-3-methylglutaryl(HMG)-CoA reductase. The activity increased first in responseto slicing, and again in response to additional treatments suchas inoculation with an incompatible race of Phytophthora infestans,application of a hyphal wall component of the fungus or HgCl₂solution, and then decreased. Both the first and the secondincreases in activity in response to slicing and additionaltreatment with a hyphal wall component to elicit phytoalexinproduction were inhibited by blasticidin S. Properties of HMG-CoAreductase induced by slicing and by additional treatment withHgCl₂ or fungal inoculation were investigated. ² Present address: Faculty of Home Economics, Nagoya Women'sUniversity, Shioji-cho, Mizuho, Nagoya 467, Japan.     

Triterpenes from Periandra dulcis roots

Three oleanane triterpenes were isolated from the roots of Periandra dulcis,and identified as 3β-hydroxy-25-al-olean-18-en-30-oic acid (periandric acid I), 3β-hydroxy-25-al-olean-12-en-30-oic acid (periandric acid II) and 3-oxo-25-hydroxy-olean-12-en-30-oic acid. The former two compounds (periandric acids I and II) were identical with the aglycones obtained by hydrolysis of periandrin I and II, respectively and the latter one was a new triterpene.     

Micelle formation of diacylglycerophosphocholines in organic solvents I. effects of the solvents on krafft points

Krafft points of diacylglycerophosphocholines (PC) were measured in alkanes-cyclohexane solutions by differential scanning calorimetry, and it was found that they were regularly increased following the increase in alkane content in the solutions and the chain length of the alkanes. From these results it was deduced that the mixing of PC with alkanes occurred in the gel state of the PC, but not in micelles at higher temperatures above the Krafft points. where micellar solutions are provided. The penetration of alkanes into gel state PC was found to be dominated by Langmuir type interaction, and the affinity of alkanes increases with increasing in chain lengths. Above the Krafft points, the micelle formation was confirmed by using the fluorescence probe technique.     

Incorporation of methionine by a soluble enzyme system from Escherichia coli

A soluble fraction from Escherichia coli B was found to incorporate methionine into 95°C CCl₃COOH-insoluble fraction. The incorporation required methionyl-tRNA synthetase, methionine tRNA, ATP, Mg²⁺ and bovine milk casein. The casein could be replaced by arginylated bovine serum albumin and arginylated bovine α-lactalbumin. A mixture of 19 amino acids other than methionine and GTP had no effect on the incorporation. KCl was rather inhibitory. Puromycin, RNase A and trypsin inhibited the incorporation, while DNase I did not. The soluble fraction also incorporated the methionyl moiety of methionyl-tRNA. This incorporation was not affected by the addition of free methionine.     

Identification of the mouse H-ficolin gene as a pseudogene and orthology between mouse ficolins A/B and human L-/M-ficolins

Ficolin is a collagenous lectin which plays a crucial role in innate immunity. Three and two ficolins have been identified in human and mice, respectively. To identify the mouse homologue of human H-ficolin and to elucidate the orthology between mouse ficolins A/B and human L-/M-ficolins, the gene structures were explored. The mouse homologue of the H-ficolin gene was identified as a pseudogene on chromosome 4. The mouse ficolin A gene was located far from the ficolin B gene on chromosome 2, whereas the human L-ficolin and M-ficolin genes were close in the region homologous to the ficolin B locus. Together with the exon-intron structures and the phylogenetic tree, these results suggest that ficolin B is the mouse orthologue of M-ficolin and that the genes encoding serum-type ficolins, ficolin A and L-ficolin, were generated independently from the ficolin B/M-ficolin lineage each in mice and primates.