Identification of two novel phytosiderophores secreted by perennial grasses

It has been suggested that some perennial grasses secrete phytosiderophores in response to iron (Fe) deficiency, but the compounds have not been identified. Here, we identified and characterized the phytosiderophores secreted by two perennial grasses, Lolium perenne cv. Tove and Poa pratensis cv. Baron. Root exudates were collected from the roots of Fe-deficient grasses and then purified with various chromatographies. The structure of the purified compounds was determined using both nuclear magnetic resonance and fast atom bombardment mass spectrometry. Both species secreted phytosiderophores in response to Fe deficiency, and the amount of phytosiderophores secreted increased with the development of Fe deficiency. The type of phytosiderophores secreted differed with plant species; L. perenne cv. Tove secreted 3-epihydroxy-2'-deoxymugineic acid (epiHDMA), 2'-deoxymugineic acid (DMA) and an unknown compound, whereas P. pratensis cv. Baron secreted DMA, avenic acid A (AVA) and an unknown compound. Purification and subsequent analysis with nuclear magnetic resonance and mass led to identification of the two novel phytosiderophores; 3-hydroxy-2'-deoxymugineic acid (HDMA) from L. perenne, and 2'-hydroxyavenic acid A (HAVA) from P. pratensis. Both novel phytosiderophores have similar chelating activity to known phytosiderophores.     

A novel sphingosine-1-phosphate receptor agonist KRP-203 attenuates rat autoimmune myocarditis

Sphingosine-1-phosphate (S1P) is an active sphingolipid metabolite that exerts important biological effects. Recently, we demonstrated that KRP-203 is a novel S1P receptor agonist that can alter lymphocyte homing and act as an immunomodulating agent. We investigated the efficacy of KRP-203 in the treatment of rat experimental autoimmune myocarditis. KRP-203 significantly attenuated the inflammation area, heart weight/body weight ratio, and left ventricular function. Immunohistochemical analysis and RT-PCR revealed that KRP-203 significantly decreased the infiltration of macrophages and CD4 T cells in the myocardium and the expression of inflammatory cytokines. Flow cytometric analysis revealed that treatment with KRP-203 effectively reduced the number of peripheral CD4 and CD8 T cells but not that of B cells and granulocytes. Further, late KRP-203 treatment was effective even against established EAM. These results demonstrate the therapeutic potential of KRP-203 for the treatment of human myocarditis and provide new insights into the pathogenesis of this disease.     

Complete nucleotide sequence of the freshwater unicellular cyanobacterium Synechococcus elongatus PCC 6301 chromosome: gene content and organization

The entire genome of the unicellular cyanobacterium Synechococcus elongatus PCC 6301 (formerly Anacystis nidulans Berkeley strain 6301) was sequenced. The genome consisted of a circular chromosome 2,696,255 bp long. A total of 2,525 potential protein-coding genes, two sets of rRNA genes, 45 tRNA genes representing 42 tRNA species, and several genes for small stable RNAs were assigned to the chromosome by similarity searches and computer predictions. The translated products of 56% of the potential protein-coding genes showed sequence similarities to experimentally identified and predicted proteins of known function, and the products of 35% of the genes showed sequence similarities to the translated products of hypothetical genes. The remaining 9% of genes lacked significant similarities to genes for predicted proteins in the public DNA databases. Some 139 genes coding for photosynthesis-related components were identified. Thirty-seven genes for two-component signal transduction systems were also identified. This is the smallest number of such genes identified in cyanobacteria, except for marine cyanobacteria, suggesting that only simple signal transduction systems are found in this strain. The gene arrangement and nucleotide sequence of Synechococcus elongatus PCC 6301 were nearly identical to those of a closely related strain Synechococcus elongatus PCC 7942, except for the presence of a 188.6 kb inversion. The sequences as well as the gene information shown in this paper are available in the Web database, CYORF (http://www.cyano.genome.jp/).     

Rapid quantification of bacterial cells in potable water using a simplified microfluidic device

A simplified microfluidic device for quantification of bacteria in potable water was fabricated and examined. Comparisons of counts of Escherichia coli by the microfluidic system and by epifluorescence microscopy closely correlated (r2=0.99). Bacteria in natural mineral water and in purified household tap water were accurately enumerated by using this system within 15 min after fluorescent staining.     

Insulin-like growth factor (IGF)-II regulates CCAAT/enhancer binding protein alpha expression via phosphatidyl-inositol 3 kinase in human hepatoblastoma cell lines

To reveal growth factor and its signal pathway to CCAAT/enhancer binding protein alpha (C/EBPalpha) in hepatocyte differentiation, we used Huh-6 and HepG2, human hepatoblastoma (HBL) cell lines that maintain the expression of genes in hepatoblasts and remain at that stage of differentiation. Insulin-like growth factor (IGF)-II, hepatocyte growth factor (HGF), and dexamethasone (Dex) stimulated HBL cells for Northern blot analysis. Bromodeoxyuridine (BrdU) up-take assay and Western blot analysis on albumin was performed to unveil proliferation and differentiation activity of IGF-II. C/EBPalpha and phosphorylation of Akt were analyzed by Western blot analysis. LY294002 and wortmannin, specific inhibitors of PI3 kinase, and PD98059, a specific inhibitor of mitogen-activated protein (MAP) kinase, were used to examine the signaling pathway of C/EBPalpha upregulated by IGF-II. Luciferase assay was performed to study the promoter activity of C/EBPalpha. Actinomycin D was used to analyze half-life of C/EBPalpha mRNA. IGF-II up-regualted C/EBPalpha by Northern blot and Western blot while HGF and Dex did not by Northern blot. IGF-II promoted proliferation and differentiation by BrdU up-take assay and Western blot analysis on albumin. Akt phosphorylated by IGF-II, suggested that phosphatidyl-inositol (PI) 3 kinase mediated the signaling pathway of IGF-II. LY294002 and wortmannin suppressed expression of C/EBPalpha. IGF-II activated the promoter activity and prolonged half-life of mRNA, suggesting that IGF-II activated promoter and stabilized mRNA. LY294002 and wortmannin suppressed the promoter activity of C/EBPalpha while PD98059 did not, suggesting that activation of the promoter was mediated by PI3 kinase.     

Regulation of food intake in the goldfish by interaction between ghrelin and orexin

Intracerebroventricular (ICV) administration of ghrelin, orexin and neuropeptide Y (NPY) stimulates food intake in goldfish. Orexin and NPY interact with each other in the regulation of feeding, while ghrelin-induced feeding has also shown to be mediated by NPY in the goldfish model. To investigate the interaction between ghrelin and orexin, we examined the effects of a selective orexin receptor-1 antagonist, SB334867, and a growth hormone secretagogue-receptor antagonist, [D-Lys(3)]-GHRP-6, on ghrelin- and orexin-A-induced feeding. Ghrelin-induced food intake was completely inhibited for 1h following ICV preinjection of SB334867, while [D-Lys(3)]-GHRP-6 attenuated orexin-A stimulated feeding. Furthermore, ICV administration of ghrelin or orexin-A at a dose sufficient to stimulate food intake increased the expression of each other's mRNA in the diencephalon. These results indicate that, in goldfish, ghrelin and orexin-A have interacting orexigenic effects in the central nervous system. This is the first report that orexin-A-induced feeding is mediated by the ghrelin signaling in any animal model.     

Effect of dietary oils on lymphocyte immunological activity in psychologically stressed mice

Psychological stress has been shown to modulate immune functions. In this study, we investigated the effect of dietary oils (olive oil, soybean oil, and fish oil) on the social isolation stress-induced modulation of lymphocyte immunological activities in mice. In olive oil-fed, but not soybean oil- or fish oil-fed, mice, a 2-week isolation stress decreased the lymphocyte proliferative response, reduced the interferon-gamma and interleukin (IL)-10 secretions and increased the IL-4 secretion by lymphocytes. The isolation stress reduced the arachidonic acid content of lymphocytes markedly, moderately, and not at all in the olive oil-, soybean oil-, and fish oil-fed mice, respectively. In the olive oil-fed, but not soybean oil- or fish oil-fed, mice, the isolation stress up-regulated the expression level of mRNA for splenic heat-shock protein 70 and increased lymphocyte sensitivity to the antiproliferative effect of corticosterone. This is the first demonstration that effect of psychological stress on lymphocyte immunological activities can vary depending upon the dietary fatty acid composition.