A single amino acid mutation in SNAP-25 induces anxiety-related behavior in mouse

Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic protein essential for neurotransmitter release. Previously, we demonstrate that protein kinase C (PKC) phosphorylates Ser(187) of SNAP-25, and enhances neurotransmitter release by recruiting secretory vesicles near to the plasma membrane. As PKC is abundant in the brain and SNAP-25 is essential for synaptic transmission, SNAP-25 phosphorylation is likely to play a crucial role in the central nervous system. We therefore generated a mutant mouse, substituting Ser(187) of SNAP-25 with Ala using "knock-in" technology. The most striking effect of the mutation was observed in their behavior. The homozygous mutant mice froze readily in response to environmental change, and showed strong anxiety-related behavior in general activity and light and dark preference tests. In addition, the mutant mice sometimes exhibited spontaneously occurring convulsive seizures. Microdialysis measurements revealed that serotonin and dopamine release were markedly reduced in amygdala. These results clearly indicate that PKC-dependent SNAP-25 phosphorylation plays a critical role in the regulation of emotional behavior as well as the suppression of epileptic seizures, and the lack of enhancement of monoamine release is one of the possible mechanisms underlying these defects.     

Elucidation of crucial structures for a catechol-based inhibitor of plasma hyaluronan-binding protein (factor VII activating protease) autoactivation

Plasma hyaluronan-binding protein (PHBP) is a serine protease the activation of which is implicated in inflammation. Previous investigations have suggested the presence of catechol-binding sites in its proenzyme form, pro-PHBP. Here we found that compounds with plural catechol groups conjugated with strong electron-withdrawing groups, such as tyrphostin AG 537 (IC(50)=18 nM), were potent inhibitors of pro-PHBP activation.     

Mice lacking alpha1,3-fucosyltransferase IX demonstrate disappearance of Lewis x structure in brain and increased anxiety-like behaviors

The 3-fucosyl-N-acetyllactosamine [Lewis x (Le(x)), CD15, SSEA-1] carbohydrate structure is expressed on several glycolipids, glycoproteins, and proteoglycans of the nervous system and has been implicated in cell-cell recognition, neurite outgrowth, and neuronal migration during development. To characterize the functional role of Le(x) carbohydrate structure in vivo, we have generated mutant mice that lack alpha1,3-fucosyltransferase IX (Fut9(-/-)). Fut9(-/-) mice were unable to synthesize the Le(x) structure carried on glycoproteins and glycolipids in embryonic and adult brain. However, no obvious pathological differences between wild-type and Fut9(-/-) mice were found in brain. In behavioral tests, Fut9(-/-) mice exhibited increased anxiety-like responses in dark-light preference and in elevated plus maze tests. Immunohistochemical analysis showed that the number of calbindin-positive neurons was decreased in the basolateral amygdala in Fut9(-/-) mice. These observations indicated that the carbohydrates synthesized by Fut9 play critical roles in functional regulations of interneurons in the amygdalar subdivisions and suggested a role for the Le(x) structure in some aspects of emotional behavior in mice.     

Hydrogen-Deuterium Exchange Effects on β-Endorphin Release from AtT20 Murine Pituitary Tumor Cells

Abundant evidences demonstrate that deuterium oxide (D₂O) modulates various secretory activities, but specific mechanisms remain unclear. Using AtT20 cells, we examined effects of D₂O on physiological processes underlying β-endorphin release. Immunofluorescent confocal microscopy demonstrated that 90% D₂O buffer increased the amount of actin filament in cell somas and decreased it in cell processes, whereas β-tubulin was not affected. Ca²⁺ imaging demonstrated that high-K⁺-induced Ca²⁺ influx was not affected during D₂O treatment, but was completely inhibited upon D₂O washout. The H₂O/D₂O replacement in internal solutions of patch electrodes reduced Ca²⁺ currents evoked by depolarizing voltage steps, whereas additional extracellular H₂O/D₂O replacement recovered the currents, suggesting that D₂O gradient across plasma membrane is critical for Ca²⁺ channel kinetics. Radioimmunoassay of high-K⁺-induced β-endorphin release demonstrated an increase during D₂O treatment and a decrease upon D₂O washout. These results demonstrate that the H₂O-to-D₂O-induced increase in β-endorphin release corresponded with the redistribution of actin, and the D₂O-to-H₂O-induced decrease in β-endorphin release corresponded with the inhibition of voltage-sensitive Ca²⁺ channels. The computer modeling suggests that the differences in the zero-point vibrational energy between protonated and deuterated amino acids produce an asymmetric distribution of these amino acids upon D₂O washout and this causes the dysfunction of Ca²⁺ channels.     

Rice plant development: from zygote to spikelet

Rice is becoming a model plant in monocotyledons and a model cereal crop. For better understanding of the rice plant, it is essential to elucidate the developmental programs of the life cycle. To date, several attempts have been made in rice to categorize the developmental processes of some organs into substages. These studies are based exclusively on the morphological and anatomical viewpoints. Recent advancement in genetics and molecular biology has given us new aspects of developmental processes. In this review, we first describe the phasic development of the rice plant, and then describe in detail the developmental courses of major organs, leaf, root and spikelet, and specific organs/tissues. Also, for the facility of future studies, we propose a staging system for each organ.     

Changes in eicosapentaenoic acid content of Navicula saprophila, Rhodomonas salina and Nitzschia sp. under mixotrophic conditions

Three species of microalgae able to produce eicosapentaenoic acid(EPA) were collected from brackish and sea water around Japan. The species were identified as Navicula saprophila, Rhodomonassalina and Nitzschia sp. EPA as a proportion of total fatty acids increased in the presence of acetic acid for Rhodomonas salina and Nitzschia sp. However, Navicula saprophila displayed the greatest productivity of EPA and the EPA content of its biomass was enhanced under mixotrophic conditions in the presence of acetic acid. This revised version was published online in August 2006 with corrections to the Cover Date.     

Bisleuconothine A,an eburnane–aspidosperma bisindole alkaloid from Leuconotis griffithii

A new bisindole alkaloid, bisleuconothine A (1) consisting of an eburnane–aspidosperma type skeleton, was isolated from the bark of Leuconotis griffithii. The structure including absolute stereochemistry was elucidated on the basis of 2D NMR data and X-ray analysis. Bisleuconothine A (1) showed cell growth inhibitory activity against various human cancer cell lines.