Inverse synaptic tagging of inactive synapses via dynamic interaction of Arc/Arg3.1 with CaMKIIβ

The Arc/Arg3.1 gene product is rapidly upregulated by strong synaptic activity and critically contributes to weakening synapses by promoting AMPA-R endocytosis. However, how activity-induced Arc is redistributed and determines the synapses to be weakened remains unclear. Here, we show targeting of Arc to inactive synapses via a high-affinity interaction with CaMKIIβ that is not bound to calmodulin. Synaptic Arc accumulates in inactive synapses that previously experienced strong activation and correlates with removal of surface GluA1 from individual synapses. A lack of CaMKIIβ either in vitro or in vivo resulted in loss of Arc upregulation in the silenced synapses. The discovery of Arc's role in "inverse" synaptic tagging that is specific for weaker synapses and prevents undesired enhancement of weak synapses in potentiated neurons reconciles essential roles of Arc both for the late phase of long-term plasticity and for reduction of surface AMPA-Rs in stimulated neurons.     

Sialic acid catabolism and transport gene clusters are lineage specific in Vibrio vulnificus

Sialic or nonulosonic acids are nine-carbon alpha ketosugars that are present in all vertebrate mucous membranes. Among bacteria, the ability to catabolize sialic acid as a carbon source is present mainly in pathogenic and commensal species of animals. Previously, it was shown that several Vibrio species carry homologues of the genes required for sialic acid transport and catabolism, which are genetically linked. In Vibrio cholerae on chromosome I, these genes are carried on the Vibrio pathogenicity island-2 region, which is confined to pathogenic isolates. We found that among the three sequenced Vibrio vulnificus clinical strains, these genes are present on chromosome II and are not associated with a pathogenicity island. To determine whether the sialic acid transport (SAT) and catabolism (SAC) region is universally present within V. vulnificus, we examined 67 natural isolates whose phylogenetic relationships are known. We found that the region was present predominantly among lineage I of V. vulnificus, which is comprised mainly of clinical isolates. We demonstrate that the isolates that contain this region can catabolize sialic acid as a sole carbon source. Two putative transporters are genetically linked to the region in V. vulnificus, the tripartite ATP-independent periplasmic (TRAP) transporter SiaPQM and a component of an ATP-binding cassette (ABC) transporter. We constructed an in-frame deletion mutation in siaM, a component of the TRAP transporter, and demonstrate that this transporter is essential for sialic acid uptake in this species. Expression analysis of the SAT and SAC genes indicates that sialic acid is an inducer of expression. Overall, our study demonstrates that the ability to catabolize and transport sialic acid is predominately lineage specific in V. vulnificus and that the TRAP transporter is essential for sialic acid uptake.     

Induction of Cr(VI) reduction activity in an Anoxybacillus strain under heat stress: a biochemical and proteomic study

A bacterial strain, designated as TSB-6, was isolated from the sediments of a Tantloi (India) hot spring at 65 °C. The strain showed 98% 16S rRNA gene sequence similarity with Anoxybacillus kualawohkensis strain KW12 and was found to grow optimally at 37 °C. However, growing cells, cell suspensions, and cell-free extracts from 65 °C cultures showed higher Cr(VI) reduction activities when assayed at either 37 or 65 °C than those obtained from 37 °C cultures. On fractionation of extracts from cells grown at 65 °C, the chromate reductase activity assayed at 65 °C was found mostly in the soluble fraction. When log-phase cells growing at 37 °C were shifted to 65 °C, the stressed cells produced larger quantities of reactive oxygen species. Consequently, growth of the cells was retarded, but specific Cr(VI) reduction activity increased. 2D gel electrophoresis followed by MALDI-TOF MS/MS identified the proteins whose expression level changed as a result of heat stress. The upregulated set included proteins involved in cellular metabolism of sugar, nucleotide, amino acids, lipids and vitamins, oxidoreductase activity, and protein folding. The downregulated proteins are also involved in cellular metabolism, DNA binding, and environmental signal processing.     

Purification and characterization of an alkaline lipase from a newly isolated Pseudomonas mendocina PK-12CS and chemoselective hydrolysis of fatty acid ester

Lipase isolated from a soil isolate, Pseudomonas mendocina (PK-12CS) chemoselectively hydrolyzed the fatty ester group in presence of arbamate of compound 5-amino-2,4-dihydro-3H-1,2,4-triazole-3 ones, a class of compounds which are attractive starting materials for the synthesis of triazole annealed heterocycles. The enzymatic method provides an easy access to the synthesis of N-substituted glycine. Under optimized fermentation conditions the culture produced 3510 Lipolytic Units/mL of cell free fermentation broth in 20 h of fermentation. The purified lipase exhibited molecular mass of 80 kDa on SDS polyacrylamide gel electrophoresis. The enzyme was stable at room temperature for more than a month and expressed maximum activity at 37 degrees C and pH 8.     

A new structural alternative in benzo[b]furans for antimicrobial activity

Two series of 2-substituted and three new diacetyl benzofurans were synthesized through palladium-catalyzed reactions and their in vitro antimicrobial spectra were assessed. The compounds demonstrated mild to significant growth inhibition against antibiotic-susceptible standard and clinically isolated strains of Gram-positive and Gram-negative bacteria as well as human fungal pathogens. Ampicillin and kanamycin were used as references for antibacterial screening; nystatin and amphotericin B were used for antifungal screening. Varying substitution at the benzofuran moiety and subsequent antimicrobial screening identified the C-3-acetyl functionality as a new structural alternative for optimal antimicrobial property in the benzofuran class of compounds.     

A brown alga Sargassum fulvellum facilitates neuronal maturation and synaptogenesis

Sargassum fulvellum (Turner) C. Agardh is an edible brown macroalgae having pharmacological importance. In previous reports, we described the screening of marine algae for their neuritogenic activity in developing hippocampal neurons and found that ethanol extract of S. fulvellum (SFE) possesses promising neurite-outgrowth-promoting activity. In this study, we evaluated whether the initial neurite promoting effect of SFE was followed on the further neuronal maturation and synapse formation. SFE exhibited dose-dependent effect on neurite maturation with an optimum concentration of 5???g/mL. The initial neuronal differentiation is significantly promoted by SFE. Subsequently, compared with control culture, SFE increased the indices of axonal and dendritic developments such as the number and the length of primary processes, and branching frequencies. In addition to its effect on neurite development, SFE significantly increased the number of puncta for postsynaptic density-95, synaptic vesicle 2, and synapse (about 35%, 67%, and 125%, respectively, of control). Moreover, SFE dose-dependently protects neurons from naturally occurring death in normal culture condition. Taken together, our data demonstrate that SFE can promote neuronal maturation and synaptogenesis and support neuronal survival, suggesting the beneficial effect of this alga in nervous system.     

Role of PKCα-p(38)MAPK-G(i)α axis in NADPH oxidase derived O(2)(·-)-mediated activation of cPLA(2) under U46619 stimulation in pulmonary artery smooth muscle cells

We have recently reported that treatment of bovine pulmonary artery smooth muscle cells with the thromboxane A(2) mimetic, U46619 stimulated NADPH oxidase derived O(2)(·-) level, which subsequently caused marked increase in [Ca(2+)](i)[17]. Herein, we demonstrated that O(2)(·-)-mediated increase in [Ca(2+)](i) stimulates an aprotinin sensitive proteinase activity, which proteolytically activates PKC-α under U46619 treatment to the cells. The activated PKC-α then phosphorylates p(38)MAPK and that subsequently caused G(i)α phosphorylation leading to stimulation of cPLA(2) activity in the cell membrane.