Cyclic GMP-gated CNG channels function in Sema3A-induced growth cone repulsion

Cyclic nucleotide-gated channels (CNGCs) transduce external signals required for sensory processes, e.g., photoreception, olfaction, and taste. Nerve growth cone guidance by diffusible attractive and repulsive molecules is regulated by differential growth cone Ca2+ signaling. However, the Ca2+-conducting ion channels that transduce guidance molecule signals are largely unknown. We show that rod-type CNGC-like channels function in the repulsion of cultured Xenopus spinal neuron growth cones by Sema3A, which triggers the production of the cGMP that activates the Xenopus CNGA1 (xCNGA1) subunit-containing channels in interneurons. Downregulation of xCNGA1 or overexpression of a mutant xCNGA1 incapable of binding cGMP abolished CNG currents and converted growth cone repulsion to attraction in response to Sema3A. We also show that Ca2+ entry through xCNGCs is required to mediate the repulsive Sema3A signal. These studies extend our knowledge of the function of CNGCs by demonstrating their requirement for signal transduction in growth cone guidance.     

The origin of an unusually large 19F chemical shift difference between the diastereomeric alpha-cyano-alpha-fluoro-p-tolylacetic acid (CFTA) esters of 3',4',5,7-tetra-O-methylepicatechin

During a study on the relationship between the (19)F chemical shift difference for the diastereomeric alpha-cyano-alpha-fluoro-p-tolylacetic acid (CFTA) esters of chiral secondary alcohols and the absolute configurations of the alcohols, an unusually large 19F chemical shift difference has been observed for the CFTA esters of 3',4',5,7-tetra-O-methylepicatechin. This large chemical shift difference has been reproduced by ab initio calculations of molecular geometry and GIAO calculations of 19F chemical shifts on the stable conformations of the diastereomeric alpha-cyano-alpha-fluorophenylacetic acid (CFPA) esters of cis-flavan-3-ol as model systems. The origin of the large chemical shift difference has been further investigated using NBO analysis. This revealed that the interaction between pi(C=C) of the aryl group in the chiral auxiliary and sigma*(C--F) is a very important determinant of the 19F chemical shifts and this interaction depends on the torsion angle between the plane of aryl group and the C--F bond.     

Photoisomerization of 2-[3-(2-thioxopyrrolidin-3-ylidene)methyl]-tryptophan, a yellow pigment in salted radish roots

The photostability of (E)-2-[3-(2-thioxopyrrolidin-3-ylidene)methyl]-tryptophan ((E)-TPMT), the main yellow pigment in salted radish, was studied. First we analyzed the photoproduct generated from (E)-TPMT under longwave UV irradiation. On the basis of NMR spectroscopy, the photoproduct was identified as Z-configurated TPMT, and isomerization from the Z- to the E-form was reversibly induced by Vis-light irradiation. The optimum wavelength for isomerization from the E- to the Z-form was 360-380 nm, and that for isomerization from the Z- to the E-form was 440-460 nm. The E/Z-ratios in the photostationary state under UV- and Vis-light irradiation conditions were approximately 0.95:1 and 26:1 respectively. The (Z)-isomer was more sensitive to light irradiation than the (E)-isomer in the quantum yield measurement. Yellowing was dependent on the ratio of the (Z)-isomer, because the b(*) and chroma value rose with increases in the (Z)-isomer by the colorimeters. Hence, it is possible that the formation of the (Z)-isomer contribute to the yellow color of takuan-zuke during long salting and fermentation.     

Candida albicans abrogates the expression of interferon-gamma-inducible protein-10 in human keratinocytes

Candida albicans is the predominant causative agent of human cutaneous candidiasis. Epidermal keratinocytes play an important role in the cutaneous immune response through the production of cytokines and chemokines, including IFN-gamma-inducible protein 10 (IP-10). Here, we investigated the influence of C. albicans infection on IP-10 production by normal human epidermal keratinocytes (NHEK) in vitro. Our results showed that IFN-gamma-stimulated NHEK showed enhanced IP-10 mRNA and protein expression; this expression was downregulated by C. albicans infection. Candida tropicalis also impaired IFN-gamma-induced IP-10 expression, but Candida glabrata did not. Heat-killed C. albicans did not impair IFN-gamma-induced IP-10 expression. We found that coincubation of NHEK with live C. albicans without cell-to-fungi contact impaired IFN-gamma-induced IP-10 mRNA and protein expression in NHEK, suggesting the role of soluble factors derived from live C. albicans in this impairment. Enzyme-linked immunosorbent assay analysis revealed that C. albicans and C. tropicalis could produce marked levels of prostaglandin (PG) E(2), while C. glabrata produced low levels of this prostaglandin. Treatment with E-series prostaglandin receptor antagonists, AH6809 and AH23848, restored IFN-gamma-induced IP-10 expression in C. albicans-infected NHEK. Thus, Candida-derived PGE(2) may impair IFN-gamma-induced IP-10 expression in human keratinocytes and may play a role in the pathogenesis of cutaneous candidiasis.     

Helicobacter and Gastric Malignancies

Individuals infected with Helicobacter pylori , a stomach colonizing bacteria, have an increased risk of developing gastric malignancies. The risk for developing cancer relates to the physiologic and histologic changes that H. pylori infection induces in the stomach. In the last year numerous studies have been conducted in order to characterize the association between H. pylori infection and gastric cancer. These studies range from epidemiologic approaches aiming at the identification of environmental, host genetic, and bacterial factors associated with risk of gastric cancer, to molecular and cell biology approaches aiming at understanding the interaction between H. pylori and the transforming epithelial cell. In this review an account of the last year's research activity on the relationship between H. pylori and gastric cancer will be given.     

A CD63 mutant inhibits T-cell tropic human immunodeficiency virus type 1 entry by disrupting CXCR4 trafficking to the plasma membrane

We have discovered that an N-terminal deletion mutant of a membrane protein, CD63, (CD63ΔN) blocks entry of CXCR4-using, T-cell tropic human immunodeficiency virus type 1 (X4 HIV-1) by suppressing CXCR4 surface expression. This suppression was observed for CXCR4 but not for CD4, CCR5, CD25, CD71 or other tetraspanin proteins. The suppression of CXCR4 expression on the plasma membrane appeared to be caused by mislocalization of CXCR4 and exclusive transportation of CXCR4 toward intracellular organelles, mainly late endosomes/lysosomes. Our data suggest that CXCR4 trafficking can be modified in terms of its recruitment to the plasma membrane without enhancing the degradation or arresting vesicular transport of CXCR4.     

New species ofAcremonium, Cylindrocarpon andVerticillium from soil in the Bonin (Ogasawara) Islands, Japan

Three new soil fungi from the Bonin (Ogasawara) Islands, Japan are described:Acremonium macroclavatum, characterized by large clavate guttulate conidia;Cylindrocarpon boninense, characterized by 3–7-septate clavate macroconidia, terminal or intercalary chlamydospores, rarely produced unicellular clavate microconidia; andVerticillium hahajimaense, characterized by conidial heads bearing cylindrical conidia, and catenulate chlamydospores.     

Chronological change and the potential of recovery on the photosynthetic efficiency of Pyropia yezoensis f. narawaensis (Bangiales) during the sporelings frozen storage treatment in the Japanese Nori cultivation

The chronological change of photosynthetic efficiency in a frozen storage treatment of the Japanese Nori cultivation industry was examined in the cultivated red alga, Pyropia yezoensis f. narawaensis (Saga‐#5 Strain, Bangiales) by using pulse‐amplitude fluorometry. During the desiccation process that was conducted after the nursery cultivation season in November, the maximum quantum yield (F _v/F _m) of the gametophytic sporelings growing on the Nori‐net decreased monotonically with decreasing absolute water content (AWC), and was around 0.1 at 20% AWC. During frozen storage of the Nori‐net, the F _v/F _m of the frozen gametophyte was low but stable, and ranged between 0.10 ± 0.02 SD and 0.14 ± 0.05 SD. The magnitude of F _v/F _m for the gametophyte of the freezing treatment, after 10 min and 3 h of immersion in seawater, recovered quickly. After 10 min and 3 h of immersion, these values were 0.29 ± 0.12 SD and 0.47 ± 0.05 SD during the 14 days of freezing treatment, and 0.15 ± 0.02 SD and 0.29 ± 0.04 SD after 71 days of freezing treatment, and suggest that the ability to recover gradually decreased as the storage duration increased. The response of F _v/F _m from general cultivation (i.e., directly cultivated from the nursery cultivation season) and those after 47 days of freezing were almost identical, suggesting that the current Nori ‐net frozen storage period (6 or 7 weeks) was not detrimental to the gametophyte.