Ionotropic Receptors as a Driving Force behind Human Synapse Establishment

The origin of nervous systems is a main theme in biology and its mechanisms are largely underlied by synaptic neurotransmission. One problem to explain synapse establishment is that synaptic orthologs are present in multiple aneural organisms. We questioned how the interactions among these elements evolved and to what extent it relates to our understanding of the nervous systems complexity. We identified the human neurotransmission gene network based on genes present in GABAergic, glutamatergic, serotonergic, dopaminergic, and cholinergic systems. The network comprises 321 human genes, 83 of which act exclusively in the nervous system. We reconstructed the evolutionary scenario of synapse emergence by looking for synaptic orthologs in 476 eukaryotes. The Human–Cnidaria common ancestor displayed a massive emergence of neuroexclusive genes, mainly ionotropic receptors, which might have been crucial to the evolution of synapses. Very few synaptic genes had their origin after the Human–Cnidaria common ancestor. We also identified a higher abundance of synaptic proteins in vertebrates, which suggests an increase in the synaptic network complexity of those organisms.     

Cyclic AMP-dependent and -independent protein kinases of the water mold, Blastocladiella emersonii.

Protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) and cyclic adenosine 3',5'-monophosphate binding activities have been identified in zoospore extracts of the water mold Blastocladiella emersonii. More than 75% of these activities is found in the soluble fraction. Soluble protein kinase activity is resolved in three peaks(I, II and III) by DEAE-cellulose chromatography. Peak I is casein dependent and insensitive to cyclic AMP. Peak II is histone dependent and cyclic AMP independent; this enzyme is inhibited by the heat-stable inhibitor from bovine muscle. Peak III utilizes histone as substrate and is activated by cyclic AMP.     

Changes in cyclic AMP binding and protein kinase activities during growth and differentiation of Blastocladiella emersonii.

Multiple protein kinases in the water mould Blastocladiella emersonii are described. A cyclic AMP-independent protein kinase which prefentially phosphorylates casein remains unchanged during vegetative growth of the cells and in the two phases of differentiation: germination and sporulation. In contrast, cyclic AMP-dependent protein kinase activity and cyclic AMP binding components are induced during the sporulation.     

Induction of mutants in Saccharomyces cerevisiae by guanidine hydrochloride II. Conditions that prevent induction

The induction of ⁻ “petite” mutants by guanidine hydrochloride (GuHCl) is inhibited in several conditions. Anaerobiosis inhibited the induction either with or without cell multiplication. Both nalidixic acid (NA) and cycloheximide (CH) inhibited the induction of mutants. On the other hand, chloramphenicol (CAP) produced a dual effect: at low concentration it stimulated, at high concentration it inhibited, the induction. The effect of these different inhibitors on the transformation of ⁺ mother cells into ⁻ by GuHCl is discussed.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of <Emphasis Type="Italic">Echinacea pallida</Emphasis> from leaf explants

Summary A method has been developed for the induction of adventitious shoots from leaf tissue of Echinacea pallida with subsequent whole-plant regeneration. Proliferating callus and shoot cultures were derived from leaf tissue explants placed on Murashige and Skoog medium supplemented with 6-benzylaminopurine and naphthaleneacetic acid combinations. The optimum shoot regeneration frequency (63%) and number of shoots per explant (2.3 shoots per explant) was achieved using media supplemented with 26.6 μM 6-benzylaminopurine and 0.11 μM naphthaleneacetic acid. Rooting of regenerated shoot explants was successful on Murashige and Skoog medium, both with and without the addition of indole-3-butyric acid. All plantlets survived acclimatization, producing phenotypically normal plants in the greenhouse. This study demonstrates that leaf tissue of E. pallida is competent for adventitious shoot regeneration and establishes a useful method for the micropropagation of this important medicinal plant.     

Micropropagation ofMinthostachys mollis (H.B.K.) grieseb. and essential oil composition of clonally propagated plants

Summary Cultures ofMinthostachys mollis were established from nodal explants obtained under aseptic conditions. Explants were cultured on Murashige and Skoog (MS) half-strength medium containing 6-benzyladenine (BA), and/or naphthaleneacetic acid (NAA). Optimum numbers of healthy shoots were induced on media containing 0.05 μM NAA plus 2.2 μM BA; higher concentrations caused more hyperhydricity and less extension. Rooting was achieved on half-strength MS medium with 0.05 μM NAA. Plantlets were acclimatized and successfully transferred to soil. Essential oil composition of the regenerated plants were determined by gas chromatography/mass spectrometry and little differences were found in the essential oil composition with the plant grown in the wild.     

Three-dimensional electron microscopic imaging of membrane invaginations in Escherichia coli overproducing the chemotaxis receptor Tsr

Electron tomography is a powerful method for determining the three-dimensional structures of large macromolecular assemblies, such as cells, organelles, and multiprotein complexes, when crystallographic averaging methods are not applicable. Here we used electron tomographic imaging to determine the molecular architecture of Escherichia coli cells engineered to overproduce the bacterial chemotaxis receptor Tsr. Tomograms constructed from fixed, cryosectioned cells revealed that overproduction of Tsr led to formation of an extended internal membrane network composed of stacks and extended tubular structures. We present an interpretation of the tomogram in terms of the packing arrangement of Tsr using constraints derived from previous X-ray and electron-crystallographic studies of receptor clusters. Our results imply that the interaction between the cytoplasmic ends of Tsr is likely to stabilize the presence of the membrane networks in cells overproducing Tsr. We propose that membrane invaginations that are potentially capable of supporting axial interactions between receptor clusters in apposing membranes could also be present in wild-type E. coli and that such receptor aggregates could play an important role in signal transduction during bacterial chemotaxis.     

Calcium ion effects on cyclic adenosine 3′:5′-monophosphate bindings to the plasma membrane of Dictyostelium discoideum

The study of cell surface cyclic adenosine 3′:5′-monophosphate binding to Dictyostelium discoideum amoebae indicates that Ca²⁺ increases the number of binding sites without significantly affecting their affinity constant(s). The effects of the ion are observed immmediately (within 4 s after addition) and appear to be readily reversible. Ca²⁺ effects are observed at various temperatures and pH values and are not blocked by the presence of various metabolic inhibitors. Increases, and decreases, in the apparent number of cyclic nucleotide binding sites could also be effected by concanavalin A treatments which respectively stimulate, and inhibit cell differentiation.     

Isorhamnetin 3,7-disulphate from Flaveria bidentis

3-Glucosides and 3,5-diglucosides of pelargonidin, cyanidin, peonidin, delphinidin, petunidin and malvidin have been identified as flower pigments in Fuchsia species. These pigments in varying admixture appear to be solely responsible for different flower colours in this genus. Their production and inheritance seems to be under a complex system of genetic control.     

Regulation of tubulin and actin synthesis and accumulation during Blastocladiella emersonii development

Actin and alpha and beta-tubulin have been identified in Blastocladiella emersonii by two-dimensional gel electrophoresis and Western blotting. The kinetics of synthesis of these proteins were compared by pulse-labeling experiments with [35S]methionine and with the accumulation of their corresponding mRNAs, translated in a cell-free system. Large increases occur in the rates of actin and alpha- and beta-tubulin biosynthesis during sporulation and there is an accumulation of the corresponding mRNAs. In parallel to the increased synthesis, these cytoskeletal proteins accumulate during the late stage of sporulation.