Spinal control of afferent temperature information in the cat

The effect of picrotoxin (at sub-convulsant doses, i.v.) on the background and invoked spike activity of cat dorsal horn internerons was investigated while thermal and mechanical influences were at work on the skin receptor areas. It was found that information on skin temperature is modulated at the presynaptic level and largely mediated by competitive interaction between large and small diameter fibers.Institute of Physiology, Academy of Sciences of the Kazakh SSR, Alma Ata. Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 773–779, November–December, 1986.     

Mutational analysis of slyD, an Escherichia coli gene encoding a protein of the FKBP immunophilin family

slyD encodes a 196 amino acid polypeptide that is a member of the FKBP family of cis–trans peptidyl–prolyl isomerases (PPIases). slyD mutations affect plaque formation by the phage φX174 by blocking the action of the phage lysis protein E. Here we describe the selection of a set of spontaneous slyD mutations conferring resistance to the expression of gene E from a plasmid. These mutations occur disproportionately in residues of SlyD that, based on the structure of the prototype mammalian FKBP12, make ligand contacts with immunosuppressing drug molecules or are conserved in other FKBP proteins. A wide variation in the plating efficiency of φX174 on these E  ^R strains is observed, relative to the parental, indicating that these alleles differ widely in residual SlyD activity. Moreover, it is found that slyD mutations cause significant growth rate defects in Escherichia coli B and C backgrounds. Finally, overexpression of slyD causes filamentation of the host. Thus, among the FKBP genes found in organisms across the evolutionary spectrum, slyD is unique in having three distinct drug-independent phenotypes.     

DESCRIPTIONS OF LAST INSTAR LARVAE OF THREE ENNOMINAE (LEPIDOPTERA: GEOMETRIDAE) SPECIES FROM KOREA

Abstract Morphological features of mature larvae of Petelia rivulosa (Butler), Exangerona prattiaria (Leech) and Culcula panterinaria (Bremer & Grey) of Ennominae are described and illustrated. All specimens examined are deposited in the Insect Collection of Department of Forest Resources Protection, Kangwon National University, Korea.     

Pattern of tonic activity in different groups of rabbit superior cervical ganglion neurons

Tonic activity in rabbit superior cervical ganglion neurons was investigated using intracellular recording techniques as well as changes produced when the animal breathed a gaseous mix with a raised CO₂ level. The test neurons were divided into three groups depending on the pattern of their tonic activity and reflex change. Action potentials were produced by the activity of dominant and accessory preganglionic inputs in the firing pattern of all neuronal groups, implying the existence of other types of inputs into the neurons innervating different organs. Having analyzed changes in action potential rate and EPSP in the tonic activity of neurons from different groups, it was presumed that preganglionic fibers with a similar activity pattern converge on the majority of neurons in each group.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 665–672, September–October, 1987.     

beta-Oxidation and Glyoxylate Cycle Coupled to NADH: Cytochrome c and Ferricyanide Reductases in Glyoxysomes

Glyoxysomes isolated from castor bean (Ricinus communis L., var Hale) endosperm had NADH:ferricyanide reductase and NADH:cytochrome c reductase activities averaging 720 and 140 nanomole electrons/per minute per milligram glyoxysomal protein, respectively. These redox activities were greater than could be attributed to contamination of the glyoxysomal fractions in which 1.4% of the protein was mitochondrial and 5% endoplasmic reticulum. The NADH:ferricyanide reductase activity in the glyoxysomes was greater than the palmitoyl-coenzyme A (CoA) oxidation activity which generated NADH at a rate of 340 nanomole electrons per minute per milligram glyoxysomal protein. Palmitoyl-CoA oxidation could be coupled to ferricyanide or cytochrome c reduction. Complete oxidation of palmitoyl-CoA, yielding 14 nanomole electrons/per nanomole palmitoyl-CoA, was demonstrated with the acceptors, NAL, cytochrome c, and ferricyanide. Malate was also oxidized by glyoxysomes, if acetyl-CoA, ferricyanide, or cytochrome c was present. Glyoxysomal NADH:ferricyanide reductase activity has the capacity to support the combined rates of NADH generation by β-oxidation and the glyoxylate cycle.     

Formation of lymphocyte colonies under serum-free culture conditions in normal individuals and patients with chronic lymphocytic leukemia

This paper describes a culture system which supports the formation of B cell and some T cell colonies under serum-free conditions in peripheral blood samples of normal individuals and patients with chronic lymphocytic leukemia (CLL) of B cell type. In this system, serum is replaced by bovine serum albumin, transferrin, cholesterol, insulin and catalase or horseradish peroxidase. In addition, it is necessary to add staphylococcus protein A, mitomycin-treated T cells as feeders and phytohemagglutinin leukocyte-conditioned medium as a source of growth factors. The plating efficiency is greatly enhanced when normal cells are incubated with galactose oxidase prior to plating and when CLL cells are exposed sequentially to neuraminidase and galactose oxidase.     

Blocking action of Nephila clavata spider toxin on ionic currents activated by glutamate and its agonists in isolated hippocampal neurons

The blocking action ofNephila clavata spider neurotoxin, or JSTX, on ionic currents activated by L-glutamate and its agonists when applied to the membrane of neurons isolated from the rat hippocampus was investigated using a concentration clamp technique. Crude JSTX venom was found to block L-glutamate-, quisqualate, and kainate-activated ionic currents induced by activating non-N-methyl-D-aspartate (non-NMDA) membrane receptors. Following the effects of JSTX, ionic currents activated by L-glutamate and its agonists declined to 34–36% of their initial value with no recovery during JSTX washout. An active fraction of JSTX at concentrations of 10^–4–10^–5 produced almost total but partially reversible blockade of ionic currents. The action of JSTX became less effective during depolarization. The concentration dependence of JSTX-induced blockade of kainate-activated ionic currents was investigated and the velocity constants of interaction between the toxin and glutamate receptors obtained. It is postulated that JSTX interacts with chemically-operated non-NMDA ionic channels, blocking their transition into a number of their possible open states.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 152–160, March–April, 1989.     

Argiopine,argiopinines, and pseudoargiopinines as glutamate receptor blockers in hippocampal neurons

A homologous set of low-molecular weight compounds selectively blocking ionic currents were purified from venom from the spiderArgiope lobata with a selective blocking action on ionic currents activated by applying glutamate and its agonist kainic acid (KA) to the membrane of neurons isolated from the rat hippocampus. Three groups of these compounds — argiopine, argiopinines, and pseudoargiopinines, produced voltage-dependent glutamate- and KA-activated ionic currents at concentrations of 10^–6-10^–4 M, interacting primarily with agonist-activated ionic channels without affecting K_d values of the agonist. The blocking action could be partially reversed by argiopine application but only slightly when argiopinines and pseudoargiopinines were used. Kinetics of toxin effects on Ka-activated ionic currents showed at least two exponential components with different time constants. Simple and reversed rate constants of interaction between toxins and ionic channels were estimated from the plot of the kinetics of ionic current blockade and recovery against toxin concentration. Argiopine, argiopinines, and pseudoargiopinines lend themselves to further research into glutamate receptors of the mammalian CNS employing electrophysiological and biochemical techniques.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev, M. M. Shemyakin Institute of Bioorganic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 748–756, November–December, 1989.     

Heterochromatic regions in different Drosophila melanogaster stocks contain similar arrangements of moderate repeats with inserted copia-like elements (MDG1)

Seven out of twenty 30–50 kb genome fragments with an MDG1 copia-like element cloned in cosmids were found to carry homologous sequences which belong to a new family of non-mobile heterochromatic moderate repeats (the HMR family). These repeats along with the MDG1 copies inserted in them are under-replicated in polytene chromosomes. Such repeats may also be located in the intercalary heterochromatin site 12E of the X chromosome. Chromosomal heterochromatic regions are enriched with one of the two main genomic variants of MDG1, MDG1^het, identifiable by EcoRI restriction. From Southern DNA blot analysis the number of MDG1^het copies and their sites within the heterochromatin are invariant in all the stocks examined, while there is not a single MDG1 site along the polytene chromosomes shared by all the stocks in question.