A New Species of Acrodipsas Sands (Lepidoptera: Lycaenidae) from Inland New South Wales and Southern Queensland

Acrodipsas mortoni sp.n. from inland New South Wales and southern Queensland is described, figured, contrasted with the related A. arcana (Miller and Edwards) and assigned to the illidgei species-group.     

TTX displacement of [H3]-nitrendipine binding in developing spinal cord neurons

[3H] Nitrendipine binding was partially blocked by the presence of tetrodotoxin in developing spinal cord neurons. In young cultures, 1 micron tetrodotoxin displaced 29% and 26% of [3H] nitrendipine binding from the high and low affinity binding sites, respectively. In one month old cultures, tetrodotoxin had no effect on [3H] nitrendipine binding. The interaction between tetrodotoxin and nitrendipine in young cultures suggests ligand binding site similarities during development.     

Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential

Summary Diffusion potential of potassium ions was formed in unilamellar vesicles of phosphatidyl choline. The vesicles, which included potassium sulfate buffered with potassium phosphate, were diluted into an analogous salt solution made of sodium sulfate and sodium phosphate. The diffusion potential was created by the addition of the potassium-ionophore, valinomycin. The change in lipid microviscosity, ensuing the formation of membrane potential, was measured by the conventional method of fluorescence depolarization with 1,6-diphenyl-1,3,5-hexatriene as a probe. Lipid microviscosity was found to increase with membrane potential in a nonlinear manner, irrespective of the potential direction. Two tentative interpretations are proposed for this observation. The first assumes that the membrane potential imposes an energy barrier on the lipid flow which can be treated in terms of Boltzmann-distribution. The other interpretation assumes a decrease in lipid-free volume due to the pressure induced by the electrical potential. Since increase in lipid viscosity can reduce lateral and rotational motions, as well as increase exposure of functional membrane proteins, physiological effects induced by transmembrane potential could be associated with such dynamic changes.     

Pinocytic uptake and intracellular degradation of N-(2-hydroxypropyl)methacrylamide copolymers a potential drug delivery system

Synthetic ¹²⁵I-labelled N-(2-hydroxypropyl)methacrylamide copolymers containing four different, potentially degradable peptidyl side chains were incubated with rat visceral yolk sacs cultured in vitro. All copolymers were captured by fluid-phase pinocytosis and three of the side chains were susceptible to lysosomal hydrolysis, resulting in release of [¹²⁵I]iodotyrosine back into the culture medium. Uptake and degradation was completely inhibited by 2,4-dinitrophenol. The thiol-proteinase inhibitor leupeptin did not affect the rate of pinocytosis, but caused different degrees of inhibition of hydrolysis depending on side chain composition.     

Effects of mutation on the downfield proton nuclear magnetic resonance spectrum of the 5S RNA of Escherichia coli

The imino proton spectra of several mutants of the 5S RNA of Escherichia coli are compared with that of the wild type. Three of the variants discussed are point mutations, and the fourth is a deletion mutant lacking bases 11-69 of the parent sequence, all obtained by site-directed mutagenesis techniques. The spectroscopic effects of mutation are limited in all cases, and the differences between normal and mutant spectra can be used to make or confirm the assignments of resonances. Several new assignments in the 5S spectrum are reported. Spectroscopic differences due to sequence differences permit the products of single genes within the 5S gene family to be distinguished and their fates followed by NMR.     

Propionate and butyrate dependent bacterial sulfate reduction at extremely haloalkaline conditions and description of Desulfobotulus alkaliphilus sp. nov.

Evidence on the utilization of simple fatty acids by sulfate-reducing bacteria (SRB) at extremely haloalkaline conditions are practically absent, except for a single case of syntrophy by Desulfonatronum on acetate. Our experiments with sediments from soda lakes of Kulunda Steppe (Altai, Russia) showed sulfide production with sulfate as electron acceptor and propionate and butyrate (but not acetate) as an electron donor at a pH 10–10.5 and a salinity 70–180 g l^?1. With propionate as substrate, a highly enriched sulfidogenic culture was obtained in which the main component was identified as a novel representative of the family Syntrophobacteraceae. With butyrate as substrate, a pure SRB culture was isolated which oxidized butyrate and some higher fatty acids incompletely to acetate. The strain represents the first haloalkaliphilic representative of the family Desulfobacteraceae and is described as Desulfobotulus alkaliphilus sp. nov.     

Chicken riboflavin-binding protein. cDNA sequence and homology with milk folate-binding protein

The Rd gene is expressed in the livers and oviducts of laying hens and codes for the riboflavin-binding protein (RfBP) of egg yolk and egg white. A lambda gt11 cDNA library derived from chicken oviduct poly(A)+ RNA was screened with polyclonal rabbit antiserum to chicken RfBP. Positive clones were isolated and rescreened with a mixed oligonucleotide probe corresponding to residues 20-25 of the mature protein. The largest cDNA clone (969 base pairs) was subcloned into plasmid pIBI21, and the nucleotide sequence was determined by the dideoxynucleotide method. This clone contained the entire coding region for RfBP. The published amino acid sequence of the mature protein was confirmed. In addition, the following 17-residue signal peptide was deduced: Met-Leu-Arg-Phe-Ala-Ile-Thr-Leu-Phe-Ala-Val-Ile-Thr-Ser-Ser-Thr-Cys. Unexpectedly, the nucleotide sequence codes for 2 adjacent arginine residues at the carboxyl terminus that are not observed in the mature protein. The amino acid sequence of RfBP is homologous with bovine milk folate-binding protein. Eight of the nine pairs of cysteines involved in disulfide bonds in RfBP are conserved in folate-binding protein, as are all of the tryptophan residues. Sequence identity between homologous regions of these two vitamin-binding proteins is more than 30%.     

Identification of an enzymatic activity that hydrolyzes protein-bound ADP-ribose in skeletal muscle

An enzymatic activity present in high-speed supernatant fluids of rat skeletal muscle was found that catalyzes the release of ADP-ribose from ADP-ribosylated-modified lysozyme. The nature of the product was proved by chromatographic studies and proton nuclear magnetic resonance spectroscopy. The enzyme activity is stimulated by Mg2+, dithioerythritol, and flouride. These results and those published earlier (Soman, G., Mickelson, J.R., Louis, C.F., and Graves, D.J. (1984) Biochem. Biophys. Res. Commun. 120, 973-980) show that ADP-ribosylation is a reversible process in skeletal muscle.     

Purification of soluble guanylate cyclase from rat lung.

The soluble form of guanylate cyclase from rat lung has been purified approximately 23,000-fold to homogeneity by isoelectric precipitation, GTP-Sepharose chromatography, and preparative gel electrophoresis. A single protein-staining band is observed after analytical gel electrophoresis on either 4 or 7.5% polyacrylamide gels. The final purified enzyme has a specific activity of about 700 nmol of cyclic GMP formed/min/mg of protein at 37 degrees C in the presence of 4.8 mM MnCl2 and 100 micrometer GTP. Bovine serum albumin appears to slightly increase guanylate cyclase activity, but mainly stabilizes the purified enzyme; in its presence, specific activities in excess of 1 mumol of cyclic GMP formed/min/mg of enzyme protein can be obtained. When Mg2+ or Ca2+ are substituted for Mn2+, specific activities decrease to approximately 21 and 40 nmol of cyclic GMP formed/min/mg of protein, respectively. The apparent Michaelis constant for MnGTP in the presence of 4.8 mM MnCl2 is 10.2 micrometer. Kinetic patterns on double reciprocal plots as a function of free Mn2+ are concave downward. The native enzyme has a molecular weight of approximately 151,000 as determined on Sephacryl S-200; sodium dodecyl sulfate-polyacrylamide gel electrophoresis results in two protein-staining bands with approximate molecular weights of 79,400 and 74,000. Thus, it appears that the soluble form of guanylate cyclase from rat lung exists as a dimer.     

Elastase-like enzymes in human neutrophils localized by ultrastructural cytochemistry

The thiol ester N-t-Boc-L-alanine-p-nitrothiophenyl ester (Boc-Ala-SNp) was synthesized and applied as an ultrastructural cytochemical substrate for intracellular elastase-like enzymes. Mature human neutrophils incubated with Boc-Ala-SNp and gold ions generate an electron-dense reaction product, gold p-nitrothiophenolate, which is found in the nuclear membrane, Golgi complex, endoplasmic reticulum, mitochondria, and granules of these cells. Enzyme activity against Boc- Ala-SNp is also observed in developing monkey bone marrow neutrophils and in other blood cells. The intracellular neutrophil enzyme activity is elastase-like because it is characterized by a slightly alkaline pH optimum and is inactivated by exposure of the cells to general and specific active site inhibitors of neutrophil elastase. This substrate appears to have important potential for use in ultrastructural studies of intracellular elastase-like enzymes.