Zierane sesquiterpene lactone,cembrane and fusicoccane diterpenoids,from the Tahitian liverwort Chandonanthus hirtellus

Cembrane-type diterpenoids, 13,18,20-epi-iso-chandonanthone (1) and (8E)-4α-acetoxy-12α,13α-epoxycembra-1(15),8-diene (2), two fusicoccane-type diterpenoids, fusicoauritone 6α-methyl ether (3) and 6β,10β-epoxy-5β-hydroxyfusicocc-2-ene (4) and a zierane sesquiterpene γ-lactone, chandolide (5) were isolated from the Tahitian liverwort Chandonanthus hirtellus (Web.) Mitt., together with eight known diterpenoids, chandonanthine (6), fusicogigantone A (7), fusicogigantone B (8), fusicogigantepoxide (9), anadensin (10), fusicoauritone (11), ent-verticillol (12) and ent-epi-verticillol (13). Their structures were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analyses. Compounds 1, 5 and 10 showed weak cytotoxic activity against HL-60. Compound 3 also indicated weak cytotoxic activity against KB cell lines.     

Contribution of the Distal Pocket Residue to the Acyl-Chain-Length Specificity of (R)-Specific Enoyl-Coenzyme A Hydratases from Pseudomonas spp.

(R)-Specific enoyl-coenzyme A (enoyl-CoA) hydratases (PhaJs) are capable of supplying monomers from fatty acid β-oxidation to polyhydroxyalkanoate (PHA) biosynthesis. PhaJ1_Pp from Pseudomonas putida showed broader substrate specificity than did PhaJ1_Pa from Pseudomonas aeruginosa, despite sharing 67% amino acid sequence identity. In this study, the substrate specificity characteristics of two Pseudomonas PhaJ1 enzymes were investigated by site-directed mutagenesis, chimeragenesis, X-ray crystallographic analysis, and homology modeling. In PhaJ1_Pp, the replacement of valine with isoleucine at position 72 resulted in an increased preference for enoyl-coenzyme A (CoA) elements with shorter chain lengths. Conversely, at the same position in PhaJ1_Pa, the replacement of isoleucine with valine resulted in an increased preference for enoyl-CoAs with longer chain lengths. These changes suggest a narrowing and broadening in the substrate specificity range of the PhaJ1_Pp and PhaJ1_Pa mutants, respectively. However, the substrate specificity remains broader in PhaJ1_Pp than in PhaJ1_Pa. Additionally, three chimeric PhaJ1 enzymes, composed from PhaJ1_Pp and PhaJ1_Pa, all showed significant hydratase activity, and their substrate preferences were within the range exhibited by the parental PhaJ1 enzymes. The crystal structure of PhaJ1_Pa was determined at a resolution of 1.7 Å, and subsequent homology modeling of PhaJ1_Pp revealed that in the acyl-chain binding pocket, the amino acid at position 72 was the only difference between the two structures. These results indicate that the chain-length specificity of PhaJ1 is determined mainly by the bulkiness of the amino acid residue at position 72, but that other factors, such as structural fluctuations, also affect specificity.     

Serological survey of T-lymphocyte differentiation antigens in wild mice

Allelic distributions of Thy-1, Ly-l, and Ly-2 antigens in wild mice are characteristic of each Mus musculus subspecies. Eastern mice (M.m.molossinus, M.mmusculus, M.m.castaneus, M.m.bactrianus) express the Thy-1.1 antigen, whereas Western mice (M.m. domesticus, M.m.brevirostris) express the Thy-1.2. All mice from wild populations examined in this survey express the Ly-1.2. The Ly-2.1 is distributed in Eastern mice and some Western mice, and the Ly-2.2 is found in the remaining Western mice. Allelic distributions of these antigens were also examined in two other species, Mus spretus and Mus spicilegus. Allelic constitutions of Thy-1 and Ly-1 in these species are similar to those of Eastern mice. Some M.spicilegus, however, express the Ly-1.1 antigen. This antigenic type is not found in M.musculus. Some Eastern mice related to M.m.castaneus react weakly to Ly-1.2-specific and Ly-2.1-specific monoclonal antibodies in both the complement-mediated cytotoxicity test and the absorption test. These results suggest that M.m.castaneus has unique alleles in the Ly-1 and Ly-2 loci.     

Band Edge Engineering of Oxide Photoanodes for Photoelectrochemical Water Splitting: Integration of Subsurface Dipoles with Atomic‐Scale Control

One of the crucial parameters dictating the efficiency of photoelectrochemical water‐splitting is the semiconductor band edge alignment with respect to hydrogen and oxygen redox potentials. Despite the importance of metal oxides in their use as photoelectrodes, studies to control the band edge alignment in aqueous solution have been limited predominantly to compound semiconductors with modulation ranges limited to a few hundred mV. The ability to modulate the flat band potential of oxide photoanodes by as much as 1.3 V, using the insertion of subsurface electrostatic dipoles near a Nb‐doped SrTiO₃/aqueous electrolyte interface is reported. The tunable range achieved far exceeds previous reports in any semiconductor/aqueous electrolyte system and suggests a general design strategy for highly efficient oxide photoelectrodes.     

Interfamily Transfer of Dual NB-LRR Genes Confers Resistance to Multiple Pathogens

A major class of disease resistance (R) genes which encode nucleotide binding and leucine rich repeat (NB-LRR) proteins have been used in traditional breeding programs for crop protection. However, it has been difficult to functionally transfer NB-LRR-type R genes in taxonomically distinct families. Here we demonstrate that a pair of Arabidopsis (Brassicaceae) NB-LRR-type R genes, RPS4 and RRS1, properly function in two other Brassicaceae, Brassica rapa and Brassica napus, but also in two Solanaceae, Nicotiana benthamiana and tomato (Solanum lycopersicum). The solanaceous plants transformed with RPS4/RRS1 confer bacterial effector-specific immunity responses. Furthermore, RPS4 and RRS1, which confer resistance to a fungal pathogen Colletotrichum higginsianum in Brassicaceae, also protect against Colletotrichum orbiculare in cucumber (Cucurbitaceae). Importantly, RPS4/RRS1 transgenic plants show no autoimmune phenotypes, indicating that the NB-LRR proteins are tightly regulated. The successful transfer of two R genes at the family level implies that the downstream components of R genes are highly conserved. The functional interfamily transfer of R genes can be a powerful strategy for providing resistance to a broad range of pathogens.     

Macrophage-Specific Overexpression of Human Matrix Metalloproteinase-12 in Transgenic Rabbits

Increased matrix metalloproteinase-12 (MMP-12) has been implicated in atherosclerosis and many other inflammatory processes. To define MMP-12 functions in vivo, we generated transgenic rabbits that expressed human (h) MMP-12 gene under the control of a macrophage-specific promoter, the human scavenger receptor promoter. Two transgenic founder rabbits were found to have hMMP-12 transgene integration by Southern blot analysis. hMMP-12 mRNA was expressed in peritoneal and alveolar macrophages, and in tissues enriched in macrophages in transgenic rabbits. High levels of hMMP-12 protein were detected in the conditioned media of cultured peritoneal and alveolar macrophages from transgenic rabbits. Zymography showed that hMMP-12 secreted from macrophages possessed enzymatic activity toward β-casein. To evaluate the expression of hMMP-12 in inflammatory sites, we used carrageenan-induced granulomas as an in vivo model for tissue macrophages and foam cells. Granuloma size in transgenic rabbits was significantly increased compared to that in control rabbits, and histological examination revealed that granulomas of transgenic rabbits were enriched in macrophages associated with increased hMMP-12 expression. We believe that this transgenic rabbit model with increased expression of hMMP-12 may become a useful model for further mechanistic studies of MMP-12 in inflammatory diseases and cancer invasion; it is also an ideal model for testing the in vivo action of MMP-12 inhibitors.     

Prostaglandin E2 production in ovarian cancer cell lines is regulated by cyclooxygenase-1, not cyclooxygenase-2

The significance of cyclooxygenase-2 (COX-2) expression in ovarian cancer has been discussed. In this study, we found increased expression of COX-1 mRNA and protein in three out of 10 ovarian cancer cell lines. Prostaglandin E 2 (PGE2) production was elevated in these three cell lines, but not in other seven cell lines. COX-2 protein was not detected in any of the cell lines. Cytosolic prostaglandin E synthase (cPGES) mRNA and protein were detected in all 10 cell lines. Membrane-associated PGES-1 (mPGES-1) was detected in some of the ovarian cell lines, but its presence did not correspond with PGE2 production. In contrast, mPGES-2 mRNA and protein were detected in all 10 cell lines. A nonselective COX inhibitor (indometacin) and a selective COX-1 inhibitor (SC-560) strongly inhibited PGE2 production by the three cell lines, while selective COX-2 inhibitors (NS-398 and rofecoxib) did not inhibit PGE2 production. In addition, increased expression of COX-1, not COX-2 protein was observed in the mass of ovarian cancer tissues from 22 patients when compared with that in normal tissue. These findings suggest that COX-1 might be a major enzyme regulating PGE2 production in ovarian cancer cells.     

Neural correlates of the difference between working memory speed and simple sensorimotor speed: an fMRI study

The difference between the speed of simple cognitive processes and the speed of complex cognitive processes has various psychological correlates. However, the neural correlates of this difference have not yet been investigated. In this study, we focused on working memory (WM) for typical complex cognitive processes. Functional magnetic resonance imaging data were acquired during the performance of an N-back task, which is a measure of WM for typical complex cognitive processes. In our N-back task, task speed and memory load were varied to identify the neural correlates responsible for the difference between the speed of simple cognitive processes (estimated from the 0-back task) and the speed of WM. Our findings showed that this difference was characterized by the increased activation in the right dorsolateral prefrontal cortex (DLPFC) and the increased functional interaction between the right DLPFC and right superior parietal lobe. Furthermore, the local gray matter volume of the right DLPFC was correlated with participants' accuracy during fast WM tasks, which in turn correlated with a psychometric measure of participants' intelligence. Our findings indicate that the right DLPFC and its related network are responsible for the execution of the fast cognitive processes involved in WM. Identified neural bases may underlie the psychometric differences between the speed with which subjects perform simple cognitive tasks and the speed with which subjects perform more complex cognitive tasks, and explain the previous traditional psychological findings.