bluuebunny/crossref_metadata_2025 huggingface dataset:
HIF-1α mRNA and protein upregulation involves Rho GTPase expression during hypoxia in renal cell carcinoma
Authors: Turcotte Sandra , Desrosiers Richard R. , Béliveau Richard
Published: May 2003

The small G proteins of the Rho family are involved in reorganization of the actin cytoskeleton, cell migration and in the regulation of gene transcription. Hypoxia-induced ATP depletion results in the disruption of actin organization which could affect Rho functions. In solid tumors, regions with low oxygen tension stimulate angiogenesis in order to increase oxygen and nutrient supply. This process is mediated by stabilization of the transcriptional factor hypoxia inducible factor 1 (HIF-1), which increases vascular endothelial growth factor (VEGF) production. In this study, we investigated the activities of Rho proteins, which are key regulators of cytoskeleton organization during hypoxia in renal cell carcinoma. Caki-1 cells were exposed to hypoxia (1% O2) and exhibited increased Cdc42, Rac1 and RhoA protein expression. Immunoprecipitation of metabolically labelled RhoA showed that overexpression was at least due to neo-synthesis. The Rho GTPases overexpressed during hypoxia were mainly located at membranes and pull-down assays demonstrated that they were active since they bound GTP. RT-PCR analysis indicated that the increase in RhoA protein expression was also reflected at the mRNA level. Overexpression and activation of Rho proteins were downstream of, and dependent on, the production of reactive oxygen species (ROS) since, in the presence of an inhibitor, both the rise of ROS and upregulation of Rho proteins were abolished. Importantly,preincubation of cells with the toxin C3, which inhibits RhoA, reduced HIF-1α protein accumulation by 84% during hypoxia. Together, these results support a model where ROS upregulate Rho protein expression and where active RhoA is required for HIF-1α accumulation during hypoxia.
Connexin43 phosphorylation at S368 is acute during S and G2/M and in response to protein kinase C activation
Authors: Solan Joell L. , Fry Matthew D. , TenBroek Erica M. , Lampe Paul D.
Published: May 2003

Phorbol esters such as 12-O-tetradeconylphorbol-13-acetate (TPA)activate protein kinase C, increase Connexin43 (Cx43) phosphorylation, and decrease cell-cell communication via gap junctions in many cell types. Previous work has implicated protein kinase C (PKC) in the direct phosphorylation of Cx43 at S368, which results in a change in single channel behavior that contributes to a decrease in intercellular communication. We have examined Cx43 phosphorylation in several cell lines with an antibody specific for phosphorylated S368. We show that this antibody detects Cx43 only when it is phosphorylated at S368 and, consistent with previous results, TPA treatment causes a dramatic increase in phosphorylation at S368. However, in some cell types, the increased phosphorylation at S368 did not cause a detectable shift in migration as compared with the nonphosphorylated Cx43. Immunofluorescence showed increased S368 immunolabeling in cytoplasmic and plasma membrane structures in response to TPA. Immunoblot analysis of synchronized cells showed increased phosphorylation at S368 during S and G2/M phases of the cell cycle. S-phase cells contained more total Cx43 but assembled fewer functional gap junctional channels than G0-phase cells. Since M-phase cells also communicate poorly and contain few assembled gap junctions, phosphorylation at S368 appears to be negatively correlated with gap junction assembly. Thus, both gap junctional communication and S368 phosphorylation change during S phase and G2/M, implying that phosphorylation at S368 might play a role in key cell-cycle events.
AKAP149 is a novel PP1 specifier required to maintain nuclear envelope integrity in G1 phase
Authors: Steen Rikke L. , Beullens Monique , Landsverk Helga B. , Bollen Mathieu , Collas Philippe
Published: May 2003

Reassembly of the nuclear envelope (NE) at the end of mitosis requires targeting of the B-type lamin protein phosphatase, PP1, to the envelope by A-kinase anchoring protein AKAP149. We show here that NE-associated AKAP149 is a novel PP1-specifying subunit involved in maintaining nuclear architecture through G1 phase. PP1 remains associated with NE-bound AKAP149 during G1 but is released from AKAP149 upon S phase entry, as AKAP149 becomes serine-phosphorylated. NE-associated AKAP149 inhibits PP1 activity towards glycogen phosphorylase but enhances PP1 phosphatase activity towards B-type lamins, indicating that AKAP149 is a B-type lamin specifying subunit of PP1. In vivo dissociation of PP1 from NE-bound AKAP149 in G1-phase nuclei triggers phosphorylation and depolymerization of A- and B-type lamins. The lamins solubilize intranuclearly without affecting the inner nuclear membrane or pore complex distribution. This correlates with the induction of a G1 arrest and,ultimately, apoptosis. We propose that AKAP149-regulated PP1 activity at the NE during G1 is required to maintain nuclear integrity and cell survival.
Chromatin of endoreduplicated pavement cells has greater range of movement than that of diploid guard cells in Arabidopsis thaliana
Authors: Kato Naohiro , Lam Eric
Published: May 2003

In the current model of chromatin organization in the interphase cell nucleus, chromosomes are organized into territories. Although constrained diffusion of chromatin in interphase cells has been confirmed in all cell types examined, little is known about chromatin dynamics in plant interphase cells. In this work, we measured for the first time interphase chromatin dynamics in plants using the green-fluorescent-protein-mediated chromatin-tagging system. Moreover, we compared the dynamics of diploid guard cells and endoreduplicated pavement cells. The movement of tagged loci in live seedlings shows constrained behavior in both types of nuclei. However, we found that the apparent confinement area for tagged loci in pavement cells is over 6 times larger than it is in guard cells. These findings suggest that chromatin is anchored to some component of the nucleus and that this might be responsible for the different dynamics of chromatin diffusion between diploid cells and endoreduplicated cells.
A tyrosine-based sorting signal is involved in connexin43 stability and gap junction turnover
Authors: Thomas Marc A. , Zosso Nathalie , Scerri Isabelle , Demaurex Nicolas , Chanson Marc , Staub Olivier
Published: May 2003

The gap junction protein connexin43 is known to have a rapid turnover,involving degradation by both the proteasomal and lysosomal systems, but the structural features of connexin43 that govern these actions are not known. The connexin43 C-terminal sequence contains a proline-rich region corresponding to the consensus of a protein-protein interaction PY-motif (xPPxY), and an overlapping putative tyrosine-based sorting signal (Yxxϕ;ϕ=hydrophobic), known to play a role in the intracellular trafficking of many membrane proteins. As both motifs may control turnover of connexin43, we used a combination of metabolic radiolabelling, immuno-precipitation and functional assays to determine the possible role of these motifs in controlling degradation of human connexin43 expressed in SKHep1 cells. Mutation V289D in the tyrosine-based sorting motif increased the steady-state pool of connexin43 by approximately 3.5-fold, while mutation P283L in the PY-motif produced a comparatively modest augmentation (1.7-fold). No additive effect was observed when the overlapping tyrosine was mutated. In pulse-chase experiments, the Y286A substitution increased the half-life of connexin43 from 2 to 6 hours, indicating that the increased steady-state levels reflected reduced protein degradation. Moreover, expression at the junctional membrane,as well as gap junction-mediated intercellular communication (GJC), were nearly abolished by lysosomal inhibitors and Brefeldin A in cells expressing wild-type connexin43, but were unaffected in the tyrosine mutant. These results provide strong evidence that the tyrosine-based motif of human connexin43 is a prime determinant controlling connexin43 stability, and consequently GJC, by targeting connexin43 for degradation in the endocytic/lysosomal compartment.
Lentivirus-mediated transduction of connexin cDNAs shows level- and isoform-specific alterations in insulin secretion of primary pancreaticβ-cells
Authors: Caton David , Calabrese Alessandra , Mas Christophe , Serre-Beinier Véronique , Charollais Anne , Caille Dorothée , Zufferey Romain , Trono Didier , Meda Paolo
Published: May 2003

We have generated novel lentiviral vectors to integrate various connexin cDNAs into primary, non-dividing cells. We have used these vectors to test whether proper control of insulin secretion depends on a specific connexin isoform and/or on its level of expression. We have observed that transduced connexin32, connexin36 and connexin43 were expressed by primary adultβ-cells at membrane interfaces, were packed into typical gap junction plaques and formed functional channels that allowed a variable coupling,depending on the type and level of connexin expressed. The infected cells spontaneously reaggregated into three-dimensional pseudo-islet organs that could be maintained in culture. We have found that pseudo-islets made by cells transduced with either GFP- or connexin43-expressing lentivirus released insulin in response to various secretagogues similarly to controls. By contrast, pseudo-islets made by cells expressing connexin32, a connexin exogenous to pancreatic islets, or over-expressing connexin36, the endogenous islet connexin, featured a marked decrease in the secretory response to glucose. The data show: (1) that lentiviral vectors allow stable modulation of various connexin in primary, non-proliferating cells; (2) that specific connexin isoforms affect insulin secretion differently; and (3) that adequate levels of coupling via connexin36 channels are required for proper β-cell function.
Association of cPLA2-α and COX-1 with the Golgi apparatus of A549 human lung epithelial cells
Authors: Grewal Seema , Ponnambalam Sreenivasan , Walker John H.
Published: May 2003

Cytosolic phospholipase A2-α (cPLA2-α) is an 85 kDa, Ca2+-sensitive enzyme involved in receptor-mediated prostaglandin synthesis. In airway epithelial cells, the release of prostaglandins is crucial in regulating the inflammatory response. Although prostaglandin release has been studied in various epithelial cell models, the subcellular location of cPLA2-α in these cells is unknown. Using high-resolution confocal microscopy of the human A549 lung epithelial cell line, we show that cPLA2-α relocates from the cytosol and nuclei to a juxtanuclear region following stimulation with the Ca2+ ionophore A23187. Double staining with rhodamine-conjugated wheat germ agglutinin confirmed this region to be the Golgi apparatus. Markers specific for Golgi subcompartments revealed that cPLA2-α is predominantly located at the trans-Golgi stack and the trans-Golgi network following elevation of cytosolic Ca2+. Furthermore, treatment of cells with the Golgi-disrupting agent brefeldin A caused a redistribution of cPLA2-α, confirming that cPLA2-α associates with Golgi-derived membranes. Finally, a specific co-localization of cPLA2-α with cyclooxygenase-1 but not cyclooxygenase-2 was evident at the Golgi apparatus. These results, combined with recent data on the role of PLA2 activity in maintaining Golgi structure and function, suggest that Golgi localization of cPLA2-α may be involved in membrane trafficking in epithelial cells.
Signal pathway integration in the switch from the mitotic cell cycle to meiosis in yeast
Authors: Honigberg Saul M. , Purnapatre Kedar
Published: May 2003

Diploid yeast, like most eukaryotes, can undergo meiotic differentiation to form haploid gametes. Meiotic differentiation and cell growth (proliferation)are mutually exclusive programs, and in yeast the switch between growth and meiosis is controlled by nutritional signals. The signaling pathways that mediate nutritional controls on meiotic initiation fall into three broad classes: those that respond to nutrient starvation, those that respond to non-fermentable carbon sources, and those that respond to glucose. At the onset of meiosis, nutritional signaling pathways converge on transcriptional regulation of two genes: IME1, which encodes a transcription factor;and IME2, which encodes a protein kinase. Transcription of IME1 and IME2 trigger initiation of meiosis, and the expression of these two genes is linked with one other, with expression of later meiotic genes and with early meiotic events such as DNA replication. In addition, the signaling pathways that control IME1 and IME2expression are themselves integrated through a variety of mechanisms. Thus the signal network that controls the switch from growth to meiotic differentiation provides a signaling code that translates different combinations of extracellular signals into appropriate cellular responses.
Trafficking of signaling modules by kinesin motors
Authors: Schnapp Bruce J.
Published: May 2003

The human genome has more than 40 kinesin genes whose protein products organize intracellular traffic along microtubules. Research during the past two years has begun to elucidate the cargoes carried by kinesins and the nature of the kinesin-cargo linkage. Modular protein-protein interactions connect kinesins to diverse cellular molecules, which, apart from their other functions, serve as kinesin-cargo linkers. Many of these newly identified linkers are scaffolds for signaling pathways, and mounting evidence now indicates that kinesins transport pre-assembled signaling modules as vesicular cargo. These findings bring together two fields, signal transduction and molecular motors, and lead to a deeper understanding of the interplay between trafficking, localization and intercellular communication.
Darkness induces mobility, and saturation deficit limits questing duration, in the tickIxodes ricinus
Authors: Perret Jean-Luc , Guerin Patrick M. , Diehl Peter A. , Vlimant Michéle , Gern Lise
Published: May 2003

The behaviour of Ixodes ricinus nymphs was recorded in 10-day experiments using computer-assisted video-tracking, in the absence of any host stimuli. These ticks switch spontaneously from questing in a desiccating atmosphere to quiescence in a water-saturated atmosphere after dark. Quantification of both questing and quiescence duration demonstrates that questing duration is inversely related to saturation deficit whereas quiescence duration is not. Distance walked after quiescence increased with desiccating conditions, while the distance walked after questing remained unchanged. Almost all locomotor activities of I. ricinus occurred during darkness under either a 14 h:10 h L:D or a 8 h:4 h L:D cycle. We established that all life stages of I. ricinus are equipped to sense shifts in light intensity with bilaterally placed strings of photoreceptors. This permits I. ricinus to use onset of darkness to trigger mobility when desiccation risk is reduced in nature.
Localisation of VIP-binding sites exhibiting properties of VPAC receptors in chromaffin cells of rainbow trout (Oncorhynchus mykiss)
Authors: Montpetit Colin J. , Shahsavarani Arash , Perry Steve F.
Published: May 2003

The current model for the neuronal control of catecholamine release from piscine chromaffin cells advocates that the neurotransmitters vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are co-released with acetylcholine from preganglionic fibres upon nerve stimulation. Both VIP and PACAP elicit the secretion of exclusively adrenaline from rainbow trout chromaffin cells, which presumably arises from the activation of VPAC type receptors. Thus, the goals of the present study were (1) to localise VPAC receptors in the chromaffin cell fraction of the posterior cardinal vein (PCV) of trout and (2) to test the hypothesis that the selective secretion of adrenaline elicited by VIP could be explained by the absence of the VPAC receptors from the noradrenaline-containing cells.

Fluorescent labelling of chromaffin cells using aldehyde-induced fluorescence of catecholamines and antisera raised against dopamineβ-hydroxylase (DβH) revealed a distinct layer of chromaffin cells lining the walls of the PCV. Furthermore, specific VIP-binding sites were demonstrated on chromaffin cells using a biotinylated VIP that was previously established as being bioactive. Although multiple labelling experiments revealed that a number of DβH-positive cells were immunonegative for phenylethanolamine N-methyl transferase (PNMT;noradrenaline-containing cells versus adrenaline-containing cells,respectively), labelling of VIP-binding sites was similar to that of DβH labelling, suggesting that all chromaffin cells possess VIP-binding sites. Pharmacological assessment of the VIP-binding sites indicated that they exhibited characteristics of VPAC receptors. Specifically, the labelling of VIP-binding sites was prevented after pre-treatment of PCV tissue sections with unlabelled VIP, PACAP or the specific VPAC receptor antagonist VIP 6-28. By contrast, sections pre-treated with the PAC1 receptor blocker PACAP 6-27 displayed normal labelling of VIP-binding sites. Finally, partial cDNA clones for the trout VPAC1 and VPAC2 receptor were obtained and sequenced. Tissue distribution experiments using RT-PCR revealed the presence of VPAC1 receptor mRNA but not that of the VPAC2 receptor in the PCV tissue. The results provide direct evidence that VIP and PACAP can elicit the secretion of adrenaline from the chromaffin tissue via specific VIP-binding sites that exhibit properties of VPAC receptors. However, the selective secretion of adrenaline by VIP or PACAP cannot be explained by a lack of VIP-binding sites on the noradrenaline-containing cells.
Osmoregulation in an avian nectarivore, the whitebellied sunbirdNectarinia talatala: response to extremes of diet concentration
Authors: Fleming P. A. , Nicolson S. W.
Published: May 2003

Water intake of nectarivores is intrinsically linked to nectar concentration. Osmoregulation in whitebellied sunbirds Nectarinia talatala (body mass 9.3±0.1 g, mean ± S.D., N=7),was examined by feeding them sucrose solutions, equivalent to extreme diet concentrations (0.07–2.5 mol l–1 sucrose; 2–65%w/w), with and without supplementary drinking water. Total water gain was 33–515% of body mass daily. Cloacal fluid (CF) volume increased with diet dilution from 0.4% to 309% of body mass while increases in evaporative water loss (obtained by difference) were also recorded. Osmolality of CF demonstrated the largest scope yet recorded for a bird and was significantly correlated with water flux: mean values were 6–460 mosm kg–1 H2O (minimum 3, maximum 1900 mosm kg–1). When supplementary water was provided, its consumption by birds fed concentrated diets (2.5 mol l–1 sucrose) led to a dramatic reduction in CF osmolality, from 461±253 to 80±119 mosm kg–1 fluid. Sunbirds maintained energy balance on sucrose diets varying tenfold in concentration, from 0.25 to 2.5 mol l–1; however, on extremely dilute diets (0.07 and 0.1 mol l–1 sucrose, lower than natural nectar concentrations) their inability to maintain energy balance was probably due to excess preformed water. Total osmotic excretion and concentrations of Na+ and K+ increased with high water fluxes, and are a possible physiological constraint for nectarivorous birds on artificial dilute diets devoid of electrolytes. Even low electrolyte levels in nectars may be adequate to replace these losses, but other physiological limitations to the intake of dilute nectars are increased energetic costs of solute recovery, increased heat loss and interference with digestive processes. Sunbirds therefore deal with sugar solutions spanning the range of nectar concentrations by shutting down water excretion on concentrated diets, or, on dilute diets, by producing extremely dilute CF with some of the lowest solute concentrations recorded.
Cadmium disrupts behavioural and physiological responses to alarm substance in juvenile rainbow trout (Oncorhynchus mykiss)
Authors: Scott Graham R. , Sloman Katherine A. , Rouleau Claude , Wood Chris M.
Published: May 2003

Alarm substance is a chemical signal released from fish skin epithelial cells after a predator causes skin damage. When other prey fish detect alarm substance by olfaction, they perform stereotypical predator-avoidance behaviours to decrease predation risk. The objective of this study was to explore the effect of sublethal cadmium (Cd) exposure on the behavioural and physiological responses of juvenile rainbow trout (Oncorhynchus mykiss) to alarm substance. Waterborne exposure to 2 μg Cd l–1 for 7 days eliminated normal antipredator behaviours exhibited in response to alarm substance, whereas exposures of shorter duration or lower concentration had no effect on normal behaviour. Furthermore, dietary exposure to 3 μg Cd g–1 in the food for 7 days, which produced the same whole-body Cd accumulation as waterborne exposure to 2 μg l–1, did not alter normal behaviour,indicating that an effect specific to waterborne exposure alone (i.e. Cd accumulation in the olfactory system) results in behavioural alteration. Whole-body phosphor screen autoradiography of fish exposed to 109Cd demonstrated that Cd deposition in the olfactory system (rosette, nerve and bulb) during waterborne exposure was greater than in all other organs of accumulation except the gill. However, Cd could not be detected in the brain. A short-term elevation in plasma cortisol occurred in response to alarm substance under control conditions. Cd exposures of 2 μg l–1 waterborne and 3 μg g–1 dietary for 7 days both inhibited this plasma cortisol elevation but did not alter baseline cortisol levels. Our results suggest that exposure to waterborne Cd at environmentally realistic levels (2 μg l–1) can disrupt the normal behavioural and physiological responses of fish to alarm substance and can thereby alter predator-avoidance strategies, with potential impacts on aquatic fish communities.
Predicting metabolic rate from heart rate in juvenile Steller sea lionsEumetopias jubatus
Authors: McPhee Jan M. , Rosen David A. S. , Andrews Russel D. , Trites Andrew W.
Published: May 2003

The validity of using heart rate to estimate energy expenditure in free-ranging Steller sea lions Eumetopias jubatus was investigated by establishing whether there is a relationship between heart rate (fH)and oxygen consumption rate(V̇O2) in captive sea lions while swimming and resting. Four trained Steller sea lions (2 males and 2 females; mass 87.4–194.4 kg; age 16 months–3 years) were each equipped with a datalogger and two dorsal subcutaneous electrodes to record electrocardiograms from which fH was calculated. V̇O2 (measured using open-circuit respirometry) was simultaneously recorded while the previously fasted animals were at rest within an enclosed dry metabolic chamber or while they swam in an enclosed swim mill against water currents of various speeds (0–1.5 m s–1). The mean regression equation describing the relationship between fH (beats min–1) and V̇O2 (ml h–1 kg–0.60) for all four animals was V̇O2=(71.3fH±4.3)–(1138.5±369.6) (means± S.E.M.) (r2=0.69, P<0.01). The relationship demonstrated between fH and V̇O2 while fasting suggests that heart rate can potentially be used to monitor energy consumption in free-ranging Steller sea lions. However, a short-term feeding experiment revealed no significant increase in heart rate following a 6 kg or 12 kg meal to match the observed increase in rate of oxygen consumption. This suggests that heart rate may not accurately reflect energy consumption during digestion events. Additional research should be conducted to further elucidate how the relationship between heart rate and oxygen consumption is affected by such factors as digestive state, stress and age.
The pathway of myofibrillogenesis determines the interrelationship between myosin and paramyosin synthesis inCaenorhabditis elegans
Authors: White Glenn E. , Petry Christine M. , Schachat Fred
Published: May 2003

Examination of null mutants in myosin B and paramyosin yields insights into the complex mechanisms that regulate expression of the three major components of Caenorhabditis elegans body-wall muscle thick filaments myosin A,myosin B and paramyosin. In the absence of myosin B, paramyosin accumulation is reduced, although neither its synthesis nor that of myosin A is affected. This implies that the interaction of myosin B with paramyosin inhibits paramyosin degradation. By contrast, the absence of paramyosin results in reduced synthesis and accumulation of myosin B but has no effect on myosin A synthesis. The non-reciprocal effects of the null mutants on turnover and synthesis are best understood as an epigenetic phenomenon that reflects the pathway of thick filament assembly. The synthesis of myosin A and paramyosin,which are involved in the initial steps of thick filament formation, is independent of myosin B; however, a properly assembled paramyosin-containing thick filament core is essential for efficient synthesis of myosin B.
Intermolecular Energy-Transfer Dynamics in {Δ-[Ru(bpy)3]}{Λ-[Os(bpy)3]}(PF6)4 and rac-[Os(bpy)3](PF6)2 Crystals
Authors: Shinozaki Kazuteru , Hotta Yasutake , Otsuka Takuhiro , Kaizu Youkoh
Published: May 2003

In the crystal composed of Δ-[Ru(bpy)3]2+ and Λ-[Os(bpy)3]2+ complexes which were pseudo enantiomers the photo-excitation energy was effectively transferred from [Ru(bpy)3]2+ to [Os(pby)3]2+ (kET > 1.1 × 108 s−1). In rac-[Os(bpy)3](PF6)2 crystal the energy-transfer rates from Λ-[Os(bpy)3]2+ to Λ-[Os(bpy)3]2+ and from Λ-[Os(bpy)3]2+ to Δ-[Os(bpy)3]2+ were estimated as k⊥ = 1.8 × 106 s−1 and k// = 7.9 × 105 s−1, respectively.
Effect of ZnO Film Thicknesses on the Adhesive Strength of Electroless Cu Deposits
Authors: Sun Ren-De , Tryk Donald A , Hashimoto Kazuhito , Fujishima Akira
Published: May 2003

The effect of ZnO film thickness on the adhesive strength of electroless Cu deposited on ZnO-coated glass substrates was examined. An increase of adhesive strength of the Cu deposits with increasing ZnO film thickness was observed. Excellent adhesion was obtained on ZnO films thicker than 0.6 μm, which is considered to be associated with the formation of rougher, more porous structures. XPS data combined with SEM and AFM measurements showed that in addition to the surface area effect, the mechanical anchoring effect caused by Cu depositing deeply within the ZnO film may also play an important role in obtaining the excellent adhesion of the Cu deposits on thicker ZnO films.
Radically Polymerizable Pseudorotaxane Monomers: Versatile Building Units for Side Chain Polyrotaxane Synthesis
Authors: Takata Toshikazu , Kawasaki Hiroaki , Asai Satoko , Kihara Nobuhiro , Furusho Yoshio
Published: May 2003

Side chain polyrotaxanes were synthesized from radically polymerizable pseudorotaxane monomers (DB24C8·1) which were composed of secondary ammonium salts having (meth)acryl group at one end and bulky stopper at the other end (1a and 1b) and dibenzo-24-crown-8 (DB24C8). Both radical polymerization of DB24C8·1 and copolymerization of DB24C8·1a with styrene afforded corresponding polymers having rotaxane moieties in the side chains (2a, 2b, and 3).
Mono- and Bilayer Equilibria of Stearate Self-Assembly Formed in Hydrotalcite Interlayers by Changing the Intercalation Temperature
Authors: Kanoh Takamitsu , Shichi Tetsuya , Takagi Katsuhiko
Published: May 2003

The self-assembly of sodium stearate and its homologs ( >C12) in hydrotalcite (LDH) interlayers was found to change reversibly between mono- and bilayer structures with a ratio changing continuously within a range of 70 °C and 5 °C in stoichiometric intercalations in aqueous dispersion. The bilayer structure was more stable than the monolayer, judging from the fact that bilayer aggregations were formed even in high temperatures with the addition of excess amounts of guest stearates over the anion exchange capacity (AEC). Hydrophobic interaction was determined to be the key factor for the formation of a bilayer assembly.
Formation of Acyliron Complexes CpFe(CO){P(OR′)3}COR′ by Reaction of Silyliron Complexes CpFe(CO)2SiR3 with Alkylphosphites P(OR′)3
Authors: Kobayashi Hideki , Ueno Keiji , Ogino Hiroshi
Published: May 2003

Heating a toluene solution of CpFe(CO)2SiR3 (R3 = HMe2, HEt2, and FMe2) and excess P(OR′)3 (R′ = Me, Et, and Me-d3) at 80 °C resulted in the formation of an acyliron complex CpFe(CO){P(OR′)3}COR′ in 25–40% yield: Hence the alkyl group of phosphite is transferred to the carbon of a carbonyl ligand to give an acyl ligand during the reaction.
Carbon-carbon Bond Forming Reactions of μ-Vinylcarbenedipalladium Complexes
Authors: Ogoshi Sensuke , Tsutsumi Ken , Shinagawa Tsutomu , Kakiuchi Kiyomi , Kurosawa Hideo
Published: May 2003

μ-η3-Vinyl(phenyl)carbenedipalladium complex reacted with tetraphenyltin to give a η3-diphenylallylpalladium complex through reductive elimination, and with internal alkynes to give μ-η2:η3-dienylcarbene complexes through migratory insertion.
Novel Phosphinite Capped Cyclodextrin-Rhodium Catalysts in Substrate Selective Hydroformylation
Authors: Deshpande Raj M , Fukuoka Atsushi , Ichikawa Masaru
Published: May 2003

A Rh-cyclodextrin phosphinite catalyst exhibits substrate selectivities in hydroformylation of C8 and C10 olefins due to the inclusion of substrates in the cyclodextrin cavity.
Electrical and Magnetic Properties of BETS Conductor with Modified λ-type Structure, λ′-(BETS)2GaBr4
Authors: Tanaka Hisashi , Kobayashi Akiko , Kobayashi Hayao
Published: May 2003

The resistivity and the magnetic susceptibility of BETS conductor with modified λ-type structure, λ′-(BETS)2GaBr4 are 0.06 Ω cm and 4 × 10−4 emu mol−1 at room temperature. In contrast to the semimetal-to-insulator transition at ambient pressure, the system showed an unusual high-pressure resistivity behavior below 50 K. Very sensitive pressure dependence of the resistivities will be consistent with the semirnetallic Fermi surface obtained by extended Hückel tight-binding band calculation.
Selective Topochemical Photoreaction of Crystallized 2,3-Bis(2-phenylethenyl)-4,5-dicyanopyrazines
Authors: Kim Jae Hong , Matsuoka Masaru , Fukunishi Koushi
Published: May 2003

Topochemical photocycloaddition of morphologically isomeric yellow and orange crystals of bis(2-phenylethenyl)dicyanopyrazine 1 were conducted in solution, in the vapor deposited thin film and in the single crystals. Photoreaction of the yellow crystal gave syn head-to-tail dimer and its polymer, but the orange crystal did not react at all. The selective topochemical photocycloaddition of 1 was discussed based upon the lattice contraction and the dynamic movement of the molecular packing arrangements.
Surface-Enhanced IR Absorption (SEIRA) of CO Adsorbed on Small Pt Particles Deposited on an Island Au Film
Authors: Sato Shinri , Kamada Koji , Osawa Masatoshi
Published: May 2003

CO adsorbed on Pt particles deposited on an island Au film exhibited strong IR adsorption. Since Au is not able to adsorb CO, this is attributable to surface-enhanced IR absorption (SEIRA) caused by the Au film. When Pt deposits were extremely small, C-O stretching band appeared at frequencies much lower than those observed for supported Pt catalysts, indicating that the Pt deposit was so small that adsorbed CO was isolated each other without a dipole-dipole interaction.
Alcohol-Induced Helix-Sheet Transition of a Sequential Alternating Amphiphilic Polypeptide
Authors: Fukushima Yasumasa
Published: May 2003

The conformation of poly(Glu-Leu-Lys-Leu) was converted a β-sheet to an α-helix by addition of alcohols. The polypeptide has two HFIP-induced conformational transitional points. The non-hydrogen bonded interactions, the hydrophobicity of the peptide surface, and the secondary structural propensities of the constituent amino acids would play a major role in the conformational transitions and secondary structural stability.
Syntheses, Structures, and Fluxional Behavior of Tricarbonylmolybdenum(0) and Trioxomolybdenum(VI) Complexes of Tris(2-pyridylmethyl)amine with One Free Arm
Authors: Xu Li , Sasaki Yoichi , Abe Masaaki
Published: May 2003

The Mo(0) and Mo(VI) complexes of tris(2-pyridylmethyl)amine (tpa), Mo(CO)3(tpa) and Mo(O)3(tpa)•H2O, were synthesized. Structural analyses revealed tridentate coordination of tpa in both compounds. The fluxional behavior of both species was investigated by variable-temperature 1H NMR spectroscopy.
Remarkable Electric Field Effect on the Absorption Intensity of a Molecular Aggregate of Photomerocyanine in a PMMA Polymer Film
Authors: Abe Shigeaki , Nishimura Yoshinobu , Yamazaki Iwao , Ohta Nobuhiro
Published: May 2003

Electroabsorption spectra of merocyanine (PMC) produced by an photochromic reaction of spiropyran (SP) in a PMMA polymer film have been measured. The intensity of the sharp absorption band assigned as an aggregate of PMC was found to be remarkably reduced by an external electric field. The photochromic reaction from the aggregate of PMC to SP is suggested to be markedly enhanced by an electric field.
Resonance Raman Spectra of Ni(II)-Tetrakis(4-methylpyridyl)porphine Interacting with Metal-Phthalocyanine Tetrasulfonate and -Phthalocyanine Derivatives Bound to Silica Gels
Authors: Saito Yutaka , Mifune Masaki , Hayashi Kenichiro , Iwado Akimasa , Onoda Midori , Haginaka Jun
Published: May 2003

Resonance Raman spectra of Ni(II)-tetrakis(4-methylpyridyl)porphine (Ni-TMPyP) were measured in the presence of Cu(II)- or Ni(II)-phthalocyanine tetrasulfonate or silica gels immobilized with Cu(II)- or Ni(II)-phthalocyanine derivative. The interaction between Ni-TMPyP and metal-phthalocyanines caused apparent changes of the resonance Raman spectra of Ni-TMPyP in water.
Peri-, Site- and Stereocontrolled Photocycloaddition of 4-Methoxy-6-methyl-2-pyrone with Maleimide Induced by the Hydrogen Bond and CT Stacking in the Solid State
Authors: Obata Toru , Shimo Tetsuro , Yoshimoto Shigeyoshi , Somekawa Kenichi , Kawaminami Masaru
Published: May 2003

Photoirradiation of a 1:1 complex crystal of 4-methoxy-6-methyl-2-pyrone (1) with maleimide (2) peri-, site- and stereospecifically gave 11-methoxy-7-methyl-4-aza-8-oxatricyclo[5.4.0.02,6]undec-10-en-3,5,9-trione (3) (endo-[2+2]adduct), which was different from the solution products. It was inferred to be effectively brought by two sets of the hydrogen bonding and CT stacking between 1 and 2.
Ambident Reactivities of Carbenium Salts Possessing a Thiocarbonyl Group at the β-Position
Authors: Nakayama Juzo , Kitahara Taku , Sugihara Yoshiaki , Ishii Akihiko
Published: May 2003

A stable, crystalline carbenium iodide, which possesses a thiocarbonyl group at the β-position, shows ambident reactivities, thereby reacting with a hard nucleophile OH− at the carbenium carbon atom and with a soft nucleophile RLi at the thiocarbonyl sulfur atom. Thermal dissociation of the MeLi adduct to a carbene and a ketene dithioacetal is also presented.
Isolation of Bright Blue Fluorescent Substances from Sonochemical Hydroxylation of Methyl p-Cyanobenzoate
Authors: Yamada Sachiko , Hokari Hajime , Akasaka Shinji , Iwamura Michiko
Published: May 2003

Sonochemical hydroxylation of methyl p-cyanobenzoate (1a) in water gave a bright blue fluorescence, which are mainly ascribed to three new fluorescent compounds, 3-hydroxy, 2,3-and 2,5-dihydroxy derivatives of 1a. Other benzenes substituted with electron-withdrawing groups also gave similar fluorescence from their hydroxylated derivatives. Among the fluorescence substances, methyl 2,5-dihydroxybenzoate was supposed to be applicable for a fluorescent chemosensor.
Synthesis, Characterization and Structure of Mu-7, a New Layered Aluminophosphate with a 4 × 8 Network
Authors: Vidal Loïc , Gramlich Völker , Patarin Joël , Gabelica Zelimir
Published: May 2003

A new layered aluminophosphate (Mu-7) was prepared in a quasi non aqueous system, using methylformamide (MF) as solvent in addition to restricted amounts of water. MF is decomposed during the synthesis and the resulting methylamine is found occluded in the interlayer spacing of this new material. Mu-7 is built from zigzag ladder chains leading to layers containing only 4- and 8-membered rings. It is the first layered aluminophosphate having a 4 × 8 network.
Asymmetric Distribution of Artificial Boundary Lipid as Analysed by NMR Deconvolution
Authors: Ueda Takehiko , Zhou Zhe , Sunamoto Junzo
Published: May 2003

Asymmetric distribution of an artificial boundary lipid between the outer and inner leaflets of multilamellar vesicles (MLVs) was determined by the modified 1H-NMR peak deconvolution technique. The asymmetry was affected by the vesicle preparation method, suggesting that a relatively high energy state of lipid bilayer is required for the boundary lipid to promote its specific function.
DNA-Controlled Photoisomerization of Bis(2-(1-methyl-pyridinium-4-yl)vinyl)benzene
Authors: Juskowiak Bernard , Takenaka Shigeori , Takagi Makoto
Published: May 2003

The photoisomerization study of bis(2-(1-methylpyridinium-4-yl)vinyl)benzene dye in the absence and the presence of DNA revealed that the DNA affects photoisomerization quantum yields of the ligand. The DNA-promoted formation of an E,E isomer was accounted for the contribution of two factors: (i) the binding differentiation between structurally. dissimilar isomers and (ii) the quenching of ligand fluorescence by the DNA.
Reaction of {Tris[2-(dimethylamino)phenyl]germyl}lithium with Elemental Selenium: Formation of 2,2,4,4-Tetrakis[2-(dimethylamino)phenyl]-1,3,2,4-diselenadigermetane
Authors: Kawachi Atsushi , Tanaka Yoko , Tamao Kohei
Published: May 2003

The reaction of {tris[2-(dimethylamino)phenyl]germyl}lithium with elemental selenium gives 2,2,4,4-tetrakis[2-(dimethylamino)phenyl]-1,3,2,4-diselenadigermetane. The crystal structure of this heterocyclic compound has been determined by X-ray diffraction. The reaction mechanism is discussed based on the NMR monitoring.
Highly Sensitive Visual Fluorometry of Aluminium at ppb Level with Ring-like Solid Phase of Poly(vinyl alcohol)
Authors: Ishida Akihiko , Kaneko Emiko , Yotsuyanagi Takao
Published: May 2003

By constructing a self-ordered nearly perfect ring system, a new type of visual test method has been developed. Poly(vinyl alcohol) forms a sharp ring–like solid phase (10.6 mm diameter) when a 100-μl drop of its aqueous solution was evaporated on a poly(vinyl chloride) plate. Aluminium ion of 1 – 30 ppb has been determined visually as a fluorescent 1:1 chelate of 2,2′-dihydroxyazobenzene concentrated into the ring.
Conjugate Addition-Approach to End-Capping of Pseudorotaxanes for Rotaxane Synthesis
Authors: Takata Toshikazu , Kawasaki Hiroaki , Asai Satoko , Furusho Yoshio , Kihara Nobuhiro
Published: May 2003

Conjugate addition of 4-tert-butylbenzenethiol to pseudorotaxane having terminal α,β-unsaturated ester group under radical condition afforded the corresponding aryl sulfide-capped rotaxane, while conjugate addition of sodium 4-tert-butylbenzenesulfinate under acidic condition also yielded aryl sulfone-capped rotaxane.
Heteronuclear FeIIIMnIIFeIII and Homonuclear FeIIIFeIIIFeIII Complexes with a Tripodal Tetradentate Ligand
Authors: Hirotsu Masakazu , Kojima Masaaki , Mori Wasuke , Yoshikawa Yuzo
Published: May 2003

The reaction of a tripodal tetradentate ligand (H2L = N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine) with Fe(ClO4)2·6H2O and a carboxylic acid in basic methanol generates an iron(III) species under aerobic conditions. Further addition of an Mn2+ cation gave a heterotrinuclear complex, [{FeIII(L)(carboxylato)(OCH3)}2MnII]. On the other hand, an additional Fe2+ cation gave a μ3-oxo homotrinuclear complex, [{FeIII(L)(carboxylato)}2OFeIII(OCH3)]. Drastic changes in the structure were induced by the addition of metal ions.
A New Strategy for the Synthesis of Semiconductor-Metal Hybrid Nanocomposites: Electrostatic Self-Assembly of Nanoparticles
Authors: Chen Sihai , Kimura Keisaku
Published: May 2003

CdS-Au hybrid nanoparticles are synthesized through electrostatically self-assembling of the pre-formed monodisperse CdS and Au nanoparticles via the interaction between ammonium ions and carboxylate ions which were modified on CdS and Au nanoparticle surface, respectively.
Self-Assembly of Zincporphyrin Dimer and Pyromellitimide Using Two Coordination Bonds and Photoinduced Intramolecular Electron Transfer
Authors: Yamada Koji , Imahori Hiroshi , Yoshizawa Eiichi , Gosztola David , Wasielewski Michael R , Sakata Yoshiteru
Published: May 2003

Zincporphyrin dimer-pyromellitimide supramolecule has been designed and assembled using two coordination bonds. Photoinduced charge separation and charge recombination in the supramolecule were observed by picosecond time-resolved transient absorption measurements.
C60 Anion Radical Produced in γ-Irradiated C60 Powder at 77 K
Authors: Kitajima Yuichiro , Miyamoto Yoshiki , Matsuura Kaoru , Hase Hirotomo
Published: May 2003

The C60 powder was γ-irradiated at 77 K. The ESR spectrum and the near infrared spectrum of the irradiated sample have revealed for the first time that C60 monoanion radical is produced in the C60 powder at 77 K.
Perfect Control of Diastereomeric Complexation of C2-Symetric Chiral 1,1′-Bis(oxazolinyl)ferrocene Ligands
Authors: Imai Yoshitane , Zhang Wanbin , Kida Toshiyuki , Nakatsuji Yohji , Ikeda Isao
Published: May 2003

Upon complexation with Pd(II), both chiral 1,1′-bis(oxazolinyl)ferrocene ligand 1 and its planar chiral derivative 2 afforded the corresponding 1:2 ligand-Pd(II) complex. On the other hand, upon complexation with copper(I) chloride, both 1 and 2 afforded only one of the two possible diastereomeric 1:1 ligand-Cu(I) complexes. The twists of the two Cp rings of the copper(I) complexes of 1 and 2 are opposite to each other, which is ascribed to the effect of the planar chirality in 2.
2-(2-Pyridyl)ethylsilyl Group as a New Class of Electroauxiliary. Fine Tuning of the Electron Transfer Driven Reactions by the Dynamic Coordination to Silicon
Authors: Yoshida Jun-ichi , Suga Seiji , Fuke Ken-ichi , Watanabe Mitsuru
Published: May 2003

The introduction of 2-(2-pyridyl)ethyl group on silicon decreases the oxidation potentials of silyl-substituted heteroatom compounds. The molecular orbital calculations indicate that this effect is attributed to the dynamic coordination of the pyridyl group to silicon in the cation radical intermediate. Such coordination also facilitates the selective C-Si bond cleavage.
General Synthesis of Useful Chelating Reagents Having a Sugar Unit, 1,3-Diamino-2-propyl β-d-Glucopyranoside and 1,3-Diamino-2-propyl α-d-Mannopyranoside
Authors: Yano Shigenobu , Shinohara Yoshie , Mogami Kaoru , Yokoyama Mika , Tanase Tomoaki , Sakakibara Toru , Nishida Fumiko , Mochida Kenichi , Kinoshita Isamu , Doe Matsumi , Ichihara Kanako , Naruta Yoshinori , Mehrkhodavandi Parisa , Buglyó Péter , Song Bin , Orvig Chris , Mikata Yuji
Published: May 2003

Two 1,3-propanediamine derivatives bearing sugar units, 1,3-diamino-2-propyl ß-d-glucopyranoside (2-β-d-Glc-pn) and 1,3-diamino-2-propyl α-d-mannopyranoside (2-α-d-Man-pn), have been prepared and characterized. The structures of two peracetylated diazides, as well as a nickel complex of glucose-type ligand, [Ni(2-β-d-Glc-pn)2SO4] have been determined by X-ray crystallography.
Syntheses and Properties of Sila-functional Oligosiloxanes: A Simple and Practical Method for the Synthesis of 1,1,3,3-Tetra-isocyanato-1,3-disubstituted Disiloxane
Authors: Abe Yoshimoto , Abe Koji , Watanabe Miho , Gunji Takahiro
Published: May 2003

The titled disiloxanes with the substituents of methyl, vinyl, phenyl, and isocyanato group were synthesized in excellent yields by a vapor phase hydrolysis of the corresponding isocyanatosilanes using a simple reaction apparatus. The process would provide a practical method for the syntheses of not only the sila-functional disiloxanes but also the other oligosiloxanes with various functional groups.
Synthesis and Structure of a Stable Cyclic Dialkylgermylene
Authors: Kira Mitsuo , Ishida Shintaro , Iwamoto Takeaki , Ichinohe Masaaki , Kabuto Chizuko , Ignatovich Lubov , Sakurai Hideki
Published: May 2003

A stable cyclic dialkylgermylene (1) was synthesized by reductive dechlorination of the corresponding dichlorogermane (6) with sodium. Germylene 1 is monomeric both in solution and in the solid state, as observed by UV-vis spectroscopy and X-ray crystallography.
Structural and Kinetic Study on the Ligand Rearrangement Reaction of 2-Aminomethylpyridine on a Di(μ-acetato)dirhodium(II) Center
Authors: Yoshimura Takashi , Umakoshi Keisuke , Sasaki Yoichi
Published: May 2003

Three new dirhodium(II) complexes, [Rh2(μ-O2CCH3)2(O2CCH3)(amp)2]ClO4 (1) (amp = 2-aminomethylpyridine), [Rh2(μ-O2CCH3)2(amp)2](ClO4)2 (2) and [Rh2(μ-O2CCH3)2(amp)2(py)2](PF6)2 (3) were prepared and characterized by X-ray structural analysis except for 2. The first order rate constant of the conversion of 1 to 2 was (2.5 ± 0.1) × 10−4 s−1 at 75 °C in aqueous solution (I = 0.075 (LiClO4), pH = 6.5).
A Concise Synthesis of 5 R-cis-Hagen’s-Gland Lactones by Chiron Approach
Authors: Mereyala Hari Babu , Gadikota Rajendrakumar Reddy
Published: May 2003

An enantiospecific and potentially general synthesis of bicyclic lactones 1 and 2 is described by chiron approach starting from ‘diacetone-D-glucose’.
In situ STM Visualization of Fullerene Epitaxial Adlayers on Au(111) Surfaces Prepared by the Transfer of Langmuir Films
Authors: Uemura Shinobu , Ohira Akihiro , Ishizaki Takahiro , Sakata Masayo , Kunitake Masashi , Taniguchi Isao , Hirayama Chuichi
Published: May 2003

Epitaxial adlayers of fullerenes (C60 and C60/C70) on Au(111) surfaces were prepared by the simple transfer of Langmuir films at air-water interface. The structure of the adlayers are essentially same as those prepared by sublimation. The adlayers are stable and reveal no reaction in the whole double layer potential region in 0.1 M perchloric acid.
Synthesis and Characterizations of Heterometallic Lanthanide-Zinc Complexes [La2Zn2(O2CEt)8(C9H7N)2(NO3)2(H2O)2] and [Yb2Zn2(O2CEt)8(C9H7N)2(NO3)2]
Authors: Cui Yong , Zheng Fakun , Huang Jinshun
Published: May 2003

Heterotetranuclear complexes [La2Zn2(O2CEt)8(C9H7N)2(NO3)2(H2O)2] and [Yb2Zn2(O2CEt)8(C9H7N)2(NO3)2] have been prepared and structurally characterized by X-ray crystallography. Magnetic measurement of the latter case shows that there exists weak antiferromagnetic exchange interaction between a pair of Yb3+ ions.
Effective Coordination of Electron-Donating Sidearms of Double-Armed 15-Crown-5 Ethers toward Alkali Metal Cations
Authors: Muraoka Masahiro , Kajiya Hiroyuki , Zhang Wanbin , Kida Toshiyuki , Nakatsuji Yohji , Ikeda Isao
Published: May 2003

Two kinds of positional isomers of double-armed crown ethers containing quinoline moieties in the sidearms were prepared and the participation of their sidearms in the complexation with alkali metal cations was examined. The difference in the position of the two sidearms on the crown ring was found to remarkably affect the complexation properties toward alkali metal cations when both sidearms are cis configuration to the crown ring.
Synthesis and Structure of a New Layered Organic-inorganic Hybrid Compound Containing Unique Chain of CuI
Authors: Zhu Hao-guo , Yu Zhi , Cai Hu , You Xiao-zeng , Vittal Jagadese J , Tan Geoe-kheng
Published: May 2003

Synthesis and X-ray crystal structure of a novel iodocuprate(I) compound (C16H19N2)2  ∞1[Cu5I7] was reported. The unique CuI chains which result from the tetrahedron CuI4 and pseudo trigonal pyramid CuI3 through sharing edge are presented in the iodocuprate(I).
Novel Extended Linear Structure of Decavanadate Anions Linked by Bis(4-Pyridinium) Disulfide (H2dpds), {(H2dpds)2[V10O26(OH)2]·10H2O}n
Authors: Kondo Mitsuru , Fujimoto Kentaro , Okubo Takashi , Asami Akiko , Noro Shin-ichiro , Kitagawa Susumu , Ishii Tomohiko , Matsuzaka Hiroyuki
Published: May 2003

New porous coordination polymer, {(H2dpds)2[V10O26(OH)2]·10H2O}n (H2dpds = bis(4-pyridinium) disulfide), was synthesized and structurally characterized. X-ray analysis demonstrates that the decavanadate anions are doubly bridged by H2dpds ligands to provide a one-dimensional structure. This network affords channeling cavities with dimension of about 2 × 4 Å along the c-axis.