6-hydroxy-l-nicotine from Arthrobacter nicotinovorans sustain spatial memory formation by decreasing brain oxidative stress in rats

Male Wistar rats were subjected to chronic 6-hydroxy-l-nicotine treatment (6HLN, 0.3 mg/kg, i.p., seven consecutive days) and their memory performance was studied by means of Y-maze and radial arm-maze tasks. 6HLN significantly increased spontaneous alternations in Y-maze task and working memory in radial arm-maze task, suggesting effects on short-term memory, without affecting long-term memory, explored by reference memory in radial arm-maze task. In addition, 6HLN increased antioxidant enzymes activity and decreased production of lipid peroxidation, suggesting antioxidant effects. Also, the linear regression between behavioral measures and oxidative stress markers resulted in significant correlations. Therefore, positive effects of 6HLN on spatial memory may occur by antioxidant actions.     

Local delivery of CpG oligodeoxynucleotides induces rapid changes in the genital mucosa and inhibits replication,but not entry,of herpes simplex virus type 2

Mucosal surfaces are the entry sites for the vast majority of infectious pathogens and provide the first line of defense against infection. In addition to the epithelial barrier, the innate immune system plays a key role in recognizing and rapidly responding to invading pathogens via innate receptors, such as Toll-like receptors (TLR). Bacterial CpG DNA, a potent activator of innate immunity, is recognized by TLR9. Here, we confirm that local mucosal, but not systemic, delivery of CpG oligodeoxynucleotides (ODN) to the genital tract protects mice from a subsequent lethal vaginal herpes simplex virus type 2 (HSV-2) challenge. Since these effects were so local in action, we examined the genital mucosa. Local delivery of CpG ODN induced rapid proliferation and thickening of the genital epithelium and caused significant recruitment of inflammatory cells to the submucosa. Local CpG ODN treatment also resulted in inhibition of HSV-2 replication but had no effect on HSV-2 entry into the genital mucosa. CpG ODN-induced protection against HSV-2 was not associated with early increases in gamma interferon (IFN-gamma) secretion in the genital tract, and CpG ODN-treated IFN-gamma(-/-) mice were protected from subsequent challenge with a lethal dose of HSV-2. Treatment of human HEK-293 cells transfected with murine TLR9 showed that the antiviral activity of CpG ODN was mediated through TLR9. These studies suggest that local induction of mucosal innate immunity can provide protection against sexually transmitted infections, such as HSV-2 or possibly human immunodeficiency virus, at the mucosal surfaces.     

Heme regulates allosteric activation of the Slo1 BK channel

Large conductance calcium-dependent (Slo1 BK) channels are allosterically activated by membrane depolarization and divalent cations, and possess a rich modulatory repertoire. Recently, intracellular heme has been identified as a potent regulator of Slo1 BK channels (Tang, X.D., R. Xu, M.F. Reynolds, M.L. Garcia, S.H. Heinemann, and T. Hoshi. 2003. Nature. 425:531-535). Here we investigated the mechanism of the regulatory action of heme on heterologously expressed Slo1 BK channels by separating the influences of voltage and divalent cations. In the absence of divalent cations, heme generally decreased ionic currents by shifting the channel's G-V curve toward more depolarized voltages and by rendering the curve less steep. In contrast, gating currents remained largely unaffected by heme. Simulations suggest that a decrease in the strength of allosteric coupling between the voltage sensor and the activation gate and a concomitant stabilization of the open state account for the essential features of the heme action in the absence of divalent ions. At saturating levels of divalent cations, heme remained similarly effective with its influence on the G-V simulated by weakening the coupling of both Ca(2+) binding and voltage sensor activation to channel opening. The results thus show that heme dampens the influence of allosteric activators on the activation gate of the Slo1 BK channel. To account for these effects, we consider the possibility that heme binding alters the structure of the RCK gating ring and thereby disrupts both Ca(2+)- and voltage-dependent gating as well as intrinsic stability of the open state.     

Experimental Helicobacter pylori infection induces antral-predominant, chronic active gastritis in hispid cotton rats (Sigmodon hispidus)

BACKGROUND: The hispid cotton rat has proven to be an excellent animal model for a variety of human infectious disease agents. This study was performed to evaluate the use of the cotton rat as a model of Helicobacter pylori infection. MATERIALS AND METHODS: Thirty-eight inbred cotton rats were orogastrically inoculated with a human strain of H. pylori. Twenty-eight control cotton rats were dosed with vehicle only. Animals were sacrificed at 2, 4, 12, 26, or 38 weeks after inoculation for bacterial and histologic and immunologic examinations. RESULTS: Helicobacter pylori was cultured from the glandular stomach of 89% of the infected cotton rats. The level of colonization was consistently high (approximately 10(4-6) colony-forming units/g tissue). Histologically, the spiral bacteria were demonstrated on the epithelial surface and in the foveolae of the gastric mucosa with highest numbers in the antrum. H. pylori infection was associated with antral-predominant, chronic active gastritis which progressively increased in severity over time. By week 26 of infection, moderate antral gastritis had developed with frequent involvement of the submucosa and formation of lymphocytic aggregates. Splenic T cells from infected cotton rats expressed mRNAs for interferon-gamma, interleukin-4, interleukin-6, and interleukin-10 following in vitro stimulation with H. pylori. Serum levels of H. pylori-specific immunoglobulin G were significantly elevated after 12 weeks of infection. CONCLUSIONS: The H. pylori-infected cotton rat represents a novel animal model that should prove useful for studies of H. pylori-induced chronic active gastritis and factors affecting gastric colonization by this pathogen.     

Palynological variation in balsaminoid ericales. I. Marcgraviaceae

BACKGROUND AND AIMS: Marcgraviaceae are a rather small family of seven genera and approx. 130 neotropical species. This study aims to present a detailed palynological survey of the family in order to comment on the intrafamily relationships and possible correlations with pollinators. METHODS: In total, 119 specimens representing 67 species and all genera are observed using light microscopy and scanning electron microscopy. Furthermore, eight species from five genera are studied with transmission electron microscopy. KEY RESULTS: Our results show that pollen grains of Marcgraviaceae are small (20-35 microm), have three equatorial apertures, granules on the colpus membrane, oblate spheroidal to prolate spheroidal shapes, mainly psilate to perforate ornamentations, and lalongate colpus-shaped thinnings at the inner layer of the exine, and show the presence of orbicules. Based on our fragmentary knowledge of the pollination biology of the family, there are no clear correlations between pollinators and pollen features. CONCLUSIONS: The genus Marcgravia has a high percentage of reticulate sexine patterns and a relatively thin nexine. Sarcopera can be defined by the presence of an oblate spheroidal to even suboblate shape, while Ruyschia and Souroubea typically show prolate spheroidal to subprolate pollen grains. The presence of a thick foot layer in the pollen wall is characteristic of the genera Norantea, Sarcopera and Schwartzia. Pollen features that are taxonomically useful within the family are the shape, sexine sculpturing, and ultrastructure of the pollen wall.     

Identification of candidate substrates for ectodomain shedding by the metalloprotease-disintegrin ADAM8

ADAM proteases are type I transmembrane proteins with extracellular metalloprotease domains. As for most ADAM family members, ADAM8 (CD156a, MS2) is involved in ectodomain shedding of membrane proteins and is linked to inflammation and neurodegeneration. To identify potential substrates released under these pathologic conditions, we screened 10-mer peptides representing amino acid sequences from extracellular domains of various membrane proteins using the ProteaseSpot system. A soluble ADAM8 protease containing a pro- and metalloprotease domain was expressed in E. coli and purified as active protease owing to autocatalytic prodomain removal. From 34 peptides tested in the peptide cleavage assay, significant cleavage by soluble ADAM8 was observed for 14 peptides representing membrane proteins with functions in inflammation and neurodegeneration, among them the beta-amyloid precursor protein (APP). The in vivo relevance of the ProteaseSpot method was confirmed by cleavage of full-length APP with ADAM8 in human embryonic kidney 293 cells expressing tagged APP. ADAM8 cleaved APP with similar efficiency as ADAM10, whereas the inactive ADAM8 mutant did not. Exchanging amino acids at defined positions in the cleavage sequence of myelin basic protein (MBP) revealed sequence criteria for ADAM8 cleavage. Taken together, the results allowed us to identify novel candidate substrates that could be cleaved by ADAM8 in vivo under pathologic conditions.     

High-affinity AKAP7delta-protein kinase A interaction yields novel protein kinase A-anchoring disruptor peptides

PKA (protein kinase A) is tethered to subcellular compartments by direct interaction of its regulatory subunits (RI or RII) with AKAPs (A kinase-anchoring proteins). AKAPs preferentially bind RII subunits via their RII-binding domains. RII-binding domains form structurally conserved amphipathic helices with unrelated sequences. Their binding affinities for RII subunits differ greatly within the AKAP family. Amongst the AKAPs that bind RIIalpha subunits with high affinity is AKAP7delta [AKAP18delta; K(d) (equilibrium dissociation constant) value of 31 nM]. An N-terminally truncated AKAP7delta mutant binds RIIalpha subunits with higher affinity than the full-length protein presumably due to loss of an inhibitory region [Henn, Edemir, Stefan, Wiesner, Lorenz, Theilig, Schmidtt, Vossebein, Tamma, Beyermann et al. (2004) J. Biol. Chem. 279, 26654-26665]. In the present study, we demonstrate that peptides (25 amino acid residues) derived from the RII-binding domain of AKAP7delta bind RIIalpha subunits with higher affinity (K(d)=0.4+/-0.3 nM) than either full-length or N-terminally truncated AKAP7delta, or peptides derived from other RII binding domains. The AKAP7delta-derived peptides and stearate-coupled membrane-permeable mutants effectively disrupt AKAP-RII subunit interactions in vitro and in cell-based assays. Thus they are valuable novel tools for studying anchored PKA signalling. Molecular modelling indicated that the high affinity binding of the amphipathic helix, which forms the RII-binding domain of AKAP7delta, with RII subunits involves both the hydrophobic and the hydrophilic faces of the helix. Alanine scanning (25 amino acid peptides, SPOT technology, combined with RII overlay assays) of the RII binding domain revealed that hydrophobic amino acid residues form the backbone of the interaction and that hydrogen bond- and salt-bridge-forming amino acid residues increase the affinity of the interaction.     

Protein identification and tracking in two-dimensional electrophoretic gels by minimal protein identifiers

Protein identification by matrix-assisted laser desorption/ionization mass-spectrometry peptide mass fingerprinting (MALDI-MS PMF) represents a cornerstone of proteomics. However, it often fails to identify low-molecular-mass proteins, protein fragments, and protein mixtures reliably. To overcome these limitations, PMF can be complemented by tandem mass spectrometry and other search strategies for unambiguous protein identification. The present study explores the advantages of using a MALDI-MS-based approach, designated minimal protein identifier (MPI) approach, for protein identification. This is illustrated for culture supernatant (CSN) proteins of Mycobacterium tuberculosis H37Rv after separation by two-dimensional gel electrophoresis (2-DE). The MPI approach takes into consideration that proteins yield characteristic peptides upon proteolytic cleavage. In this study, peptide mixtures derived from tryptic protein cleavage were analyzed by MALDI-MS and the resulting spectra were compared with template spectra of previously identified counterparts. The MPI approach allowed protein identification by few protein-specific signature peptide masses and revealed truncated variants of mycobacterial elongation factor EF-Tu, previously not identified by PMF. Furthermore, the MPI approach can be employed to track proteins in 2-DE gels, as demonstrated for the 14 kDa antigen, the 10 kDa chaperone, and the conserved hypothetical protein Rv0569 of M. tuberculosis H37Rv. Furthermore, it is shown that the power of the MPI approach strongly depends on distinct factors, most notably on the complexity of the proteome analyzed and accuracy of the mass spectrometer used for peptide mass determination.