The effect of neutral and charged micelles on the acid-base dissociation of the local anesthetic tetracaine

The influence of surfactant micelles on the acid-base dissociation of the charged tertiary amino group of the local anesthetic, tetracaine, has been investigated. From measurements of tetracaine fluorescence as a function of bulk pH, apparent $\text{p}\text{K}$ values of 6.88, 7.58 and 9.92 were found in the presence of cationic, neutral and anionic micelles, respectively, in 10 mM NaCl. These values are considerably displaced with respect to the $\text{p}\text{K}$ in aqueous solution which is 8.26. Such large shifts can be attributed to the effect of the surface polarity and electrical potential on the dissociation behavior of the anesthetic bound to micelles. It can be expected that the acid-base dissociation of a local anesthetic adsorbed to nerve fibers will also be affected by the properties of the membrane surface. Thus, it is suggested that the influence of the interfacial region on the $\text{p}\text{K}$ of surface-bound molecules should not be disregarded when estimating the proportion of charged and uncharged forms of local anesthetics interacting with axonal membranes.     

Characterization of Gypsy Moth (Lymantria dispar) Nuclear Polyhedrosis Virus

Characterization of the proteins and nucleic acid of the gypsy moth nuclear polyhedrosis virus isolated in Ithaca, N.Y. (LdNPV-IT) is presented. A total of 29 viral structural proteins were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis when the virus was isolated in the absence of alkaline protease activity. Fourteen surface envelope viral proteins were identified by lactoperoxidase iodination. Eleven proteins were associated with nucleocapsids prepared by Nonidet P-40 detergent treatment. Distinct alterations of viral proteins were documented when virions were purified in the presence of occlusion body-associated alkaline protease(s). Restriction enzyme digests of viral DNA indicated that this isolate was composed of a large number of genetic variants. On the basis of the major molar fragments resulting from EcoRI, BamHI, BglII, and HindIII digests, the molecular weight of the LdNPV genome was approximately 88 × 10⁶.     

Biochemical parameters to assess cell differentiation of Bouvardia ternifolia Schlecht callus

Calli derived from leaves and radicles of B. ternifolia were grown on Murashige and Skoog (MS) basal medium, and the effects of different nitrogen sources on the rate of callus growth and on the enzymes related to nitrogen assimilation were studied. Ammonium alone did not support callus growth unless a Krebs-cycle intermediate was added to the medium. The activities of glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.7.1), and glutamate dehydrogenase (EC 1.4.1.2) were measured in homogenates of callus grown on media supplied with different nitrogen sources. The results indicate that leaf and root calli have similar levels of these enzymes when grown on MS medium (Murashige and Skoog 1962. Physiol. Plant. 15, 473–497). However, when the calli were supplied with glutamine as the sole nitrogen source, the activity of glutamate synthase increased in leaf callus but was almost completely inhibited in root callus. The results indicate that calli originated from different B. ternifolia tissues do not have the same biochemical dedifferentiated state.     

The influence of sucrose, 2,4-D,and kinetin on the growth,fine structure,and lignin content of cultured sycamore cells

Summary When suspensions of sycamore cells are cultured in a synthetic medium containing 1.0 mg/l 2,4-D and 0.25 mg/l kinetin, maximum cell yield is obtained with an initial concentration of 6 per cent sucrose. There is a progressive increase in dry weight per cell, decline in extractive-free weight as a percentage of cell dry weight and increase in lignin content per cell as the initial sucrose concentration is increased from 1 per cent to 15 per cent. The percentage of lignin in the extractive-free cell residue is further enhanced by increasing the level of 2,4-D to 10 mg/l or by growing the cells in an auxin-free medium containing 10 mg/l kinetin.When the cell suspensions are treated with phloroglucinol/HCl it is found that only a proportion of the cells contain lignin, that this lignin occurs in the protoplasts and in plates between the cells, and that lignin is present in the culture medium.Electron micrographs confirmed the absence of any secondary wall such as is characteristic of tracheary elements. Cells cultured in the presence of 6 per cent sucrose or higher levels showed numerous amyloplasts and frequently the presence of electron opaque material. This occurs in the irregular but not frequent wall thickenings, as droplets in the vacuoles and as amorphous sheets between the cells. Pictures showing such electron opaque droplets clustered on the inner face of the tonoplasts suggest that this material is formed in the cytoplasm and released into the vacuoles. In addition these cells are characterised by the presence of fine electron opaque granular material in their vacuoles and external to their protoplasts. Cultures richest in lignin showed the highest content of electron opaque globules in, and amorphous sheets between, the cells and it is suggested that these correspond to lignin or a lignin-hemicellulose complex. In the presence of 15 per cent sucrose many cells showing breakdown of organised structure were observed; they were characterised by the persistence of mitochondria and particularly of the amyloplasts and by their high content of the electron opaque material equated with lignin. This material was also present in the dead cells.     

Operon fusions of Mu d1(Ap,lac) to thel-proline biosynthetic genes ofescherichia coli K-12

Operon fusions to the promoter of either theproA,proB, orproC genes of the proline biosynthetic pathway were obtained by the use of the Mu d1(Ap,lac) bacteriophage. These fusions were further stabilized by transformation with plasmid pGW600 containing the wildtype Mu repressor gene or by transduction with phage pSG1. The level of -galactosidase in the fusion strains was not affected by the presence of exogenously addedl-proline or high concentrations of NaCl in the growth medium. A Tn5 insertion nearproBA increased -galactosidase expression 140- to 200-fold in strains carrying theproA-lac andproB-lac fusions, but the level of this enzyme was unaltered in strains carrying theproC-lac fusion. The Tn5 insertion increased intracellular proline concentrations 8- to 10-fold, suggesting that mechanisms other than allosteric inhibition may regulate proline biosynthesis, but did not confer osmotolerance to cells growing in a medium with a high concentration of salt.     

Metabolism of ethylene in olive leaves

Olive tree tissues are able to metabolize ethylene. This metabolism is inhibited by heat killing and carbon disulfide. Rubber stoppers usually employed to close the incubation vials release carbon disulfide, thereby modifying the values obtained for ethylene. The ethylene consumption rate has been found to be 9 nl/h.g, an intermediate value among the different plant tissues so far examined.     

Quantitation of molybdopterin oxidation product in wild-type and molybdenum cofactor deficient mutants of Chlamydomonas reinhardtii.

A simple and reliable procedure of oxidation of molybdenum cofactor (MoCo) from molybdoenzymes by autoclaving samples at 120 degrees C for 20 min yielded a single predominant fluorescent species that could be quantitatively determined by reverse phase high performance liquid chromatography. This method allowed detection and quantitation of molybdopterin in cell-free extracts of the green alga Chlamydomonas reinhardtii. The MoCo oxidation product from C. reinhardtii has the same chromatographic and spectral properties as that of milk xanthine oxidase and chicken liver sulfite oxidase. The oxidized species was also detected in molybdenum cofactor mutants of Chlamydomonas reinhardtii defective at the nit-3, nit-4, nit-5/nit-6 and nit-7 loci, which strongly suggests that active molybdenum cofactor itself is not directly involved in the control of its own biosynthetic pathway.