Search

Background Currently, the data on the relationship between obesity and gastroesophageal reflux disease (GERD) in Asian populations are scarce. Methods The aim of this study is to investigate the prevalence of reflux esophagitis (RE) among obese Japanese patients in each body mass index (BMI) range group. In addition, we aim to investigate the risk factors for RE in obese Japanese patients. The present retrospective cohort study included 674 obese Japanese patients who underwent bariatric surgery between January 2003 and April 2016. The patients were stratified into five groups based on BMI range. Results The mean BMI was 42.7 ± 9.24 kg/m2. The prevalence of RE among each of the groups was as follows: Group 1 (BMI 30–34.9) = 20.7%; Group 2 (BMI 35–39.9) = 24.0%; Group 3 (BMI 40–44.9) = 25.2%; Group 4 (BMI 45–49.9) = 26.7%; and Group 5 (BMI ≥50) = 24.8%. Overall, the prevalence of RE was 24.2% in our study. Furthermore, no significant difference in BMI was noted between the RE and non‐RE groups (43.4 ± 9.3 kg/m2 and 42.5 ± 10.2 kg/m2, respectively; p = 0.24). According to the multivariate logistic regression model, gender, Helicobacter pylori infection status, GERD‐related symptoms, and hiatal hernia were significantly correlated with RE. Conclusion Our study shows that the prevalence of RE in severely obese Japanese patients was significantly higher than the average prevalence of RE in Japan. However, the prevalence of RE did not increase with BMI in our cohort., Our study is the first to report the prevalence of RE in severely obese Japanese patients. Although it has certain limitations, it can still provide valuable reference data in epidemiology.

Aggressive social interactions are used to compete for limited resources and are regulated by complex sensory cues and the organism’s internal state. While both sexes exhibit aggression, its neuronal underpinnings are understudied in females. Here, we identify a population of sexually dimorphic aIPg neurons in the adultDrosophila melanogastercentral brain whose optogenetic activation increased, and genetic inactivation reduced, female aggression. Analysis of GAL4 lines identified in an unbiased screen for increased female chasing behavior revealed the involvement of another sexually dimorphic neuron, pC1d, and implicated aIPg and pC1d neurons as core nodes regulating female aggression. Connectomic analysis demonstrated that aIPg neurons and pC1d are interconnected and suggest that aIPg neurons may exert part of their effect by gating the flow of visual information to descending neurons. Our work reveals important regulatory components of the neuronal circuitry that underlies female aggressive social interactions and provides tools for their manipulation.

The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly’s brain., eLife digest Animal brains of all sizes, from the smallest to the largest, work in broadly similar ways. Studying the brain of any one animal in depth can thus reveal the general principles behind the workings of all brains. The fruit fly Drosophila is a popular choice for such research. With about 100,000 neurons – compared to some 86 billion in humans – the fly brain is small enough to study at the level of individual cells. But it nevertheless supports a range of complex behaviors, including navigation, courtship and learning. Thanks to decades of research, scientists now have a good understanding of which parts of the fruit fly brain support particular behaviors. But exactly how they do this is often unclear. This is because previous studies showing the connections between cells only covered small areas of the brain. This is like trying to understand a novel when all you can see is a few isolated paragraphs. To solve this problem, Scheffer, Xu, Januszewski, Lu, Takemura, Hayworth, Huang, Shinomiya et al. prepared the first complete map of the entire central region of the fruit fly brain. The central brain consists of approximately 25,000 neurons and around 20 million connections. To prepare the map – or connectome – the brain was cut into very thin 8nm slices and photographed with an electron microscope. A three-dimensional map of the neurons and connections in the brain was then reconstructed from these images using machine learning algorithms. Finally, Scheffer et al. used the new connectome to obtain further insights into the circuits that support specific fruit fly behaviors. The central brain connectome is freely available online for anyone to access. When used in combination with existing methods, the map will make it easier to understand how the fly brain works, and how and why it can fail to work correctly. Many of these findings will likely apply to larger brains, including our own. In the long run, studying the fly connectome may therefore lead to a better understanding of the human brain and its disorders. Performing a similar analysis on the brain of a small mammal, by scaling up the methods here, will be a likely next step along this path.

Precise, repeatable genetic access to specific neurons via the GAL4/UAS system and related methods is a key advantage of Drosophila neuroscience. Neuronal targeting is typically documented using light microscopy of full GAL4 expression patterns, which mostly lack the single-cell resolution required for reliable cell type identification. Here we use stochastic GAL4 labeling with the MultiColor FlpOut approach to generate cellular resolution confocal images at large scale. We are releasing aligned images of 27,000 such adult central nervous systems. An anticipated use of this resource is to bridge the gap between electron microscopy-identified neurons and light microscopy-based intersectional genetic approaches such as the split-GAL4 system. Identifying the individual neurons that make up each GAL4 expression pattern improves the prediction of which GAL4 enhancer fragments best combine via split-GAL4 to target neurons of interest. To this end we have developed the NeuronBridge search tool, which matches these light microscope neuronal images to neurons in the recently published FlyEM hemibrain. This work thus provides a resource and search tool that will significantly enhance both the efficiency and efficacy of split-GAL4 targeting of EM-identified neurons and further advance Drosophila neuroscience.

Aggressive social interactions are used to compete for limited resources and are regulated by complex sensory cues and the organism’s internal state. While both sexes exhibit aggression, its neuronal underpinnings are understudied in females. Here, we describe a set of connected neurons in the adultDrosophila melanogastercentral brain that drive female aggression. We identified a population of sexually dimorphic aIPg neurons whose optogenetic activation increased, and genetic inactivation reduced, female aggression. Analysis of GAL4 lines identified in an unbiased screen for increased female chasing behavior revealed the involvement of another sexually dimorphic neuron, pC1d, and implicated pC1d and aIPg neurons as core nodes regulating female aggression. pC1d activation increased female aggression and electron microscopy (EM) connectomic analysis demonstrated that aIPg neurons and pC1d have strong reciprocal connections. Our work reveals important regulatory components of the neuronal circuitry that underlies female aggressive social interactions and provides tools for their manipulation.

The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly’s brain.

Wiring a complex brain requires many neurons with intricate cell specificity, generated by a limited number of neural stem cells. Drosophila central brain lineages are a predetermined series of neurons, born in a specific order. To understand how lineage identity translates to neuron morphology, we mapped 18 Drosophila central brain lineages. While we found large aggregate differences between lineages, we also discovered shared patterns of morphological diversification. Lineage identity plus Notch-mediated sister fate govern primary neuron trajectories, whereas temporal fate diversifies terminal elaborations. Further, morphological neuron types may arise repeatedly, interspersed with other types. Despite the complexity, related lineages produce similar neuron types in comparable temporal patterns. Different stem cells even yield two identical series of dopaminergic neuron types, but with unrelated sister neurons. Together, these phenomena suggest that straightforward rules drive incredible neuronal complexity, and that large changes in morphology can result from relatively simple fating mechanisms.

Summary Different types of Drosophila dopaminergic neurons (DANs) reinforce memories of unique valence and provide state-dependent motivational control [1]. Prior studies suggest that the compartment architecture of the mushroom body (MB) is the relevant resolution for distinct DAN functions [2, 3]. Here we used a recent electron microscope volume of the fly brain [4] to reconstruct the fine anatomy of individual DANs within three MB compartments. We find the 20 DANs of the γ5 compartment, at least some of which provide reward teaching signals, can be clustered into 5 anatomical subtypes that innervate different regions within γ5. Reconstructing 821 upstream neurons reveals input selectivity, supporting the functional relevance of DAN sub-classification. Only one PAM-γ5 DAN subtype γ5(fb) receives direct recurrent feedback from γ5β′2a mushroom body output neurons (MBONs) and behavioral experiments distinguish a role for these DANs in memory revaluation from those reinforcing sugar memory. Other DAN subtypes receive major, and potentially reinforcing, inputs from putative gustatory interneurons or lateral horn neurons, which can also relay indirect feedback from MBONs. We similarly reconstructed the single aversively reinforcing PPL1-γ1pedc DAN. The γ1pedc DAN inputs mostly differ from those of γ5 DANs and they cluster onto distinct dendritic branches, presumably separating its established roles in aversive reinforcement and appetitive motivation [5, 6]. Tracing also identified neurons that provide broad input to γ5, β′2a, and γ1pedc DANs, suggesting that distributed DAN populations can be coordinately regulated. These connectomic and behavioral analyses therefore reveal further complexity of dopaminergic reinforcement circuits between and within MB compartments., Highlights • Nanoscale anatomy reveals additional subtypes of rewarding dopaminergic neurons • Connectomics reveals input specificity to subtypes of dopaminergic neurons • Axon morphology implies dopaminergic neurons provide subcompartment-level function • Unique dopaminergic subtypes serve aversive memory extinction and sugar learning, Otto et al. use electron microscope resolution connectomics to describe the structure and organization of neurons providing synaptic input to functionally discrete subtypes of dopaminergic neurons. The nanoscale anatomy reveals further anatomical and functional specialization of dopaminergic neurons, which is confirmed with behavioral experiments.

Wiring a complex brain requires many neurons with intricate cell specificity, generated by a limited number of neural stem cells. Drosophila central brain lineages are a predetermined series of neurons, born in a specific order. To understand how lineage identity translates to neuron morphology, we mapped 18 Drosophila central brain lineages. While we found large aggregate differences between lineages, we also discovered shared patterns of morphological diversification. Lineage identity plus Notch-mediated sister fate govern primary neuron trajectories, whereas temporal fate diversifies terminal elaborations. Further, morphological neuron types may arise repeatedly, interspersed with other types. Despite the complexity, related lineages produce similar neuron types in comparable temporal patterns. Different stem cells even yield two identical series of dopaminergic neuron types, but with unrelated sister neurons. Together, these phenomena suggest that straightforward rules drive incredible neuronal complexity, and that large changes in morphology can result from relatively simple fating mechanisms.

The fruit flyDrosophila melanogasteris an important model organism for neuroscience with a wide array of genetic tools that enable the mapping of individuals neurons and neural subtypes. Brain templates are essential for comparative biological studies because they enable analyzing many individuals in a common reference space. Several central brain templates exist forDrosophila, but every one is either biased, uses sub-optimal tissue preparation, is imaged at low resolution, or does not account for artifacts. No publicly availableDrosophilaventral nerve cord template currently exists. In this work, we created high-resolution templates of theDrosophilabrain and ventral nerve cord using the best-available technologies for imaging, artifact correction, stitching, and template construction using groupwise registration. We evaluated our central brain template against the four most competitive, publicly available brain templates and demonstrate that ours enables more accurate registration with fewer local deformations in shorter time.

The GAL4-UAS system has proven its versatility in studying the function and expression patterns of neurons theDrosophilacentral nervous system. Although the GAL4 system has been used for 25 years, recent genetic intersectional tools have enabled genetic targeting of very small numbers of neurons aiding in the understanding of their function. This split-GAL4 system is extremely powerful for studying neuronal morphology and the neural basis of animal behavior. However, choosing lines to intersect that have overlapping patterns restricted to one to a few neurons has been cumbersome. This challenge is now growing as the collections of GAL4 driver lines has increased. Here we present a new method and software plug-in for Fiji to dramatically improve the speed of querying large databases of potential lines to intersect and aid in the split-GAL4 creation. We also provide pre-computed datasets for the Janelia GAL4 (5,738 lines) and VT GAL4 (7,429 lines) of the Drosophila central nervous system (CNS). The tool reduced our split-GAL4 creation effort dramatically.

Background and Aim Helicobacter pylori (H. pylori) infection is a strong risk factor for the development of gastric cancer. In 2013, the Japanese government approved H. pylori eradication therapy in patients with chronic gastritis as well as peptic ulcer. However, the continuing decline in eradication rates for first-line H. pylori eradication therapies is an urgent problem. In this study, we investigated changes in the first-line eradication rate from 2001 to 2010. Methods Eradication rates for 7-day triple therapy [proton pump inhibitor (rabeprazole 20 mg, lansoprazole 60 mg, or omeprazole 40 mg) + amoxicillin 1500 mg + clarithromycin (CAM) 400 or 800 mg, daily] were collated from 14 hospitals in the Tokyo metropolitan area. The urea breath test was used for the evaluation of eradication. The cut-off value was less than 2.5%. Results The yearly eradication rates (intention to treat/per protocol) were 78.5/79.5% (2001, n = 242), 71.2%/72.9% (2002, n = 208), 67.8%/70.5% (2003, n = 183), 75.6%/84.6% (2004, n = 131), 56.4%/70.5% (2005, n = 114), 70.5%/75.8% (2006, n = 271), 67.4%/82.0% (2007,n = 135), 64.0%/76.3% (2008, n = 261), 60.5%/74.3% (2009, n = 329), and 66.5%/78.8% (2010, n = 370), respectively. Examination of eradication rates according to CAM dosage revealed an eradication rate of 65.6% (383/584) for CAM 400 mg daily, and 68.5% (1124/1642) for CAM 800 mg daily, with no significant difference seen between dosages. Conclusion In recent years, eradication rates for first-line triple therapy have obviously decreased, but no noticeable decrease has occurred after 2001.

Summary Background During development neurons are generated by sequential divisions of neural stem cells, or neuroblasts. In the insect brain progeny of certain stem cells form lineage-specific sets of projections that arborize in distinct brain regions, called clonal units. Though this raises the possibility that the entire neural network in the brain might be organized in a clone-dependent fashion, only a small portion of clones has been identified. Results Using Drosophila melanogaster , we randomly labeled one of about 100 stem cells at the beginning of the larval stage, analyzed the projection patterns of their progeny in the adult, and identified 96 clonal units in the central part of the fly brain, the cerebrum. Neurons of all the clones arborize in distinct regions of the brain, though many clones feature heterogeneous groups of neurons in terms of their projection patterns and neurotransmitters. Arborizations of clones overlap preferentially to form several groups of closely associated clones. Fascicles and commissures were all made by unique sets of clones. Whereas well-investigated brain regions such as the mushroom body and central complex consist of relatively small numbers of clones and are specifically connected with a limited number of neuropils, seemingly disorganized neuropils surrounding them are composed by a much larger number of clones and have extensive specific connections with many other neuropils. Conclusions Our study showed that the insect brain is formed by a composition of cell-lineage-dependent modules. Clonal analysis reveals organized architecture even in those neuropils without obvious structural landmarks.

Building a sizable, complex brain requires both cellular expansion and diversification. One mechanism to achieve these goals is production of multiple transiently amplifying intermediate neural progenitors (INPs) from a single neural stem cell. Like mammalian neural stem cells, Drosophila type II neuroblasts utilize INPs to produce neurons and glia. Within a given lineage, the consecutively born INPs produce morphologically distinct progeny, presumably due to differential inheritance of temporal factors. To uncover the underlying temporal fating mechanisms, we profiled type II neuroblasts' transcriptome across time. Our results reveal opposing temporal gradients of Imp and Syp RNA-binding proteins (descending and ascending, respectively). Maintaining high Imp throughout serial INP production expands the number of neurons and glia with early temporal fate at the expense of cells with late fate. Conversely, precocious upregulation of Syp reduces the number of cells with early fate. Furthermore, we reveal that the transcription factor Seven-up initiates progression of the Imp/Syp gradients. Interestingly, neuroblasts that maintain initial Imp/Syp levels can still yield progeny with a small range of early fates. We therefore propose that the Seven-up-initiated Imp/Syp gradients create coarse temporal windows within type II neuroblasts to pattern INPs, which subsequently undergo fine-tuned subtemporal patterning.

Electron spin resonance (ESR) is a powerful technique to study the mechanochemical reactions in deformed polymeric materials including elastomers.This review gives results of ESR measurements of vulcanizates under tensile deformation. The measurements were carried out by the combination of home-built stretching machine with commercially available ESR spectrometer. The destruction and re-combination of crosslinking structure developed in the vulcanizates were confirmed by the changes of radical concentration during tensile deformation. Further, the degree of strain induced crystallization in vulcaniates was correlated with the partial breakdown of network structure in the vulcanizates.

Effects of silica on the vulcanization reaction by sulfur/N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) in isoprene rubber were studied by FT-IR and ESR. It was found that the induction time of vulcanization reaction was shortened by the addition of silica. However, the efficiency of vulcanization at the final stage of reaction was lower for silica filled sample than for unfilled one. The structure of CBS in the vulcanization system was investigated by the FT-IR at a crosslinking temperature. It was found that by the addition of silica in the system new peaks appeared at 1541 and 1598cm-1,suggesting a decomposition of CBS by silica. Further, the concentration of sulfur radical during the vulcanization was decreased by the addition of silica. However, the decomposition was suppressed by the removal of water molecules absorbed directly on silica surface. These results indicated that at an initial stage of vulcanization, most of CBS was decomposed by silanol groups which were covered with the adsorbed water, leading to the fast vulcanization reaction by sulfur, however, the concentration of CBS dropped quickly at the initial stage of vulcanization, resulting in the low efficiency of vulcanization. These results were explained by the decomposition of CBS by acid catalyst ability of silanol groups.

SummaryHow global organ asymmetry and individual cell polarity are connected to each other is a central question in studying planar cell polarity (PCP). In the Drosophila wing, which develops PCP along its proximal-distal (P-D) axis, we previously proposed that the core PCP mediator Frizzled redistributes distally in a microtubule (MT)-dependent manner. Here, we performed organ-wide analysis of MT dynamics by introducing quantitative in vivo imaging. We observed MTs aligning along the P-D axis at the onset of redistribution and a small but significant excess of + ends-distal MTs in the proximal region of the wing. This characteristic alignment and asymmetry of MT growth was controlled by atypical cadherins Dachsous (Ds) and Fat (Ft). Furthermore, the action of Ft was mediated in part by PAR-1. All these data support the idea that the active reorientation of MT growth adjusts cell polarity along the organ axis.

Electron spin resonance (ESR) and wide angle X-ray diffraction (WAXD) measurements under the tensile deformation were carried out for H-NBR, NBR and SBR vulcanizates with varying cross-link densities to discuss on the changes of network structure during tensile deformation. The H-NBR vulcanizates showed a strain-induced crystallization at room temperature, but the NBR and SBR vulcanizates did not. At a given stress, the radical concentration determined by ESR measurements was higher for H-NBR vulcanizates than for NBR and SBR vulcanizates. The degree of strain-induced crystallization at a given strain was likely to increase with the decrease of crosslink density. These results suggested that the strain-induced crystallization of H-NBR vulcanizates was accompanied by the partial breakdown of network structure in the vulcanizates.

Electron spin resonance measurements under the tensile deformation and transmission electron microscopy observations were carried out for silica filled SBR and polyisoprene vulcanizates to discuss on the mechanism of stress softening effect (Mullins effect).It was found that for unfilled vulcanizates, the breakdown of crosslinks and/or chain scission of rubber molecules are responsible for the Mullins effect. By the incorporation of silica into rubber, the Mullins effect was enhanced possibly due to the partial breakdown of silica agglomerates.

In vertebrate retinal rod outer segment (ROS),1 light signals are transduced by the photoreceptor-specific G protein transducin, which links photolysis of rhodopsin to activation of cGMP-phosphodiesterase (PDE) (1). Transducin (Tα/Tβγ) is comprised of three subunits: Tα (Mr 37000), Tβ (Mr 35000), and Tγ (Mr 8000). Tα contains a binding site for guanine nucleotide (GDP or GTP), whereas Tβ and Tγ form a tight complex (Tβγ) which associates with Tα in its GDP-bound form (Tα-GDP). In phototransduction, Tα-GDP/Tβγ forms a transient ternary complex with a photobleached active intermediate of rhodopsin, metarhodopsin II (abbreviated as Rh* in this paper). Rh* facilitates exchange of GDP bound to Tα with cytosolic GTP, resulting in dissociation of the ternary complex into Tα-GTP, Tβγ, and Rh*. A single molecule of Rh* catalyzes formation of several hundreds of Tα-GTP. The highly amplified element, Tα-GTP, in turn induces a release of the inhibitory γ-subunit from the catalytic core αβ dimer of PDE, resulting in its activation. The activated PDE hydrolyzes cGMP, which causes hyperpolarization of the membrane potential via an impact on cGMP-dependent cation channels in rod cells. Thus, Rh*-transducin coupling achieves remarkable amplification of the photon signal in retinal rod photoreceptor cells (1). We and others have reported that Tγ is farnesylated at its C-terminal cysteine residue via a thioether bond and, in addition, the C-terminal carboxyl group is methylated (2,3). Subsequent cDNA cloning studies demonstrated that the deduced amino acid sequences of all 12 known subtypes of G protein γ-subunits share a common C-terminal CAAX motif (4). It is now established that posttranslational isoprenylation of the CAAX sequence proceeds via three enzymatic steps, isoprenylation at the cysteine residue in the CAAX motif, AAX cleavage, and then carboxyl methylation. The C-terminal amino acid X is a major determinant for the modification by isoprenyl groups at the cysteine residue in the CAAX motif by either of the two cytosolic enzymes: protein farnesyltransferase (FTase) or protein geranylgeranyltransferase I (GGTase I) (4). Farnesylation (C15) by FTase occurs when X is serine, methionine, glutamine, or alanine, while the C-terminus is geranylgeranylated (C20) by GGTase I when X is leucine or phenylalanine (5). After isoprenylation, the AAX sequence in the CAAX motif is removed by a site-specific endoprotease, Ras converting enzyme 1 (Rce1) (6), and the prenylated cysteine residue newly exposed at the C-terminus is carboxyl methylated by a specific methyltransferase, isoprenylcysteine carboxyl methyltransferase (Icmt) (7,8). Rce1 and Icmt have been shown to be microsomal membrane-bound enzymes (6,7), and hence the processing of the prenylated CAAX motifs likely occurs on the microsomal membrane surface prior to the sorting of the fully processed prenylated proteins to the plasma membranes. Isoprenylation and the subsequent carboxyl methylation each confer hydrophobic property to the proteins, and therefore the modifications are generally regarded to enhance the membrane association of the protein. In fact, Gβγ or Ras proteins lacking CAAX motifs are unable to localize to plasma membranes (9,10). On the other hand, several lines of evidence have suggested that the farnesyl and geranylgeranyl groups of transducin (2,4,11–13), Ras (14), and rhodopsin kinase (15) play key roles in protein−protein interactions. For example, mutant Tβγ consisting of Tγ truncated at the C-terminus, or Tβγ lacking the farnesyl moiety, is defective in catalyzing the GDP−GTP exchange reaction on Tα in the presence of Rh* (2,11,12). It has also been shown that synthetic peptides corresponding to the C-terminal region of Tγ inhibited Tα−Tβγ interaction only when the peptides were isoprenylated (13). Tβγ has another binding partner, phosducin (16), that is a soluble 33 kDa protein abundantly present in the inner region of the rod photoreceptor cells. Although phosducin is phosphorylated in the dark, it is dephosphorylated upon receiving intense light and binds to Tβγ, which then loses its membrane-binding affinity (16,17). The physiological roles of phosducin and its light-dependent dephosphorylation are still elusive, but one of its possible roles could be to inhibit Tβγ from interacting with Tα or effectors (18). The sequestration of Tβγ by phosducin may serve as a regulatory mechanism of the light signaling (17–19). In addition to the farnesylation, the carboxyl methylation also plays a physiological role for isoprenylated proteins (20), such as Tβγ (11,12,21) and Ras (10). Our previous experiments showed that farnesylated and methylated Tβγ supported more efficiently the GDP−GTP exchange reaction on Tα catalyzed by Rh* when compared with farnesylated and nonmethylated Tβγ (11,12). More evidently, the binding of farnesylated Tβγ to the ROS membranes was strongly facilitated by the carboxyl methylation (12). Together, these data indicate that the farnesylation of Tγ is indispensable for transducin to couple with Rh*, and the carboxyl methylation synergistically enhances this coupling. In spite of such an important role(s) of the farnesyl group, the interacting target(s) of the modifying lipid has not yet been directly demonstrated at each step of the signaling process. In structural studies on G proteins, the exact location of the isoprenoid group has not been identified by X-ray crystallography because most of the studies have employed engineered proteins lacking the prenyl group (22,23). In order to investigate farnesyl-mediated molecular interactions, several groups have synthesized photoreactive farnesyl analogues, among which (2-diazo-3,3,3-trifluoropropionyloxy)geranyl pyrophosphate (abbreviated as DATFP-GPP) was successfully recognized by prenyltransferase (24,25). The interaction between the prenyltransferase and DATFP during the transfer reaction has been demonstrated, but possibly due to the chemical instability of DATFP, only a few labeling experiments have been performed successfully with the photoreactive compound incorporated into G protein after the transfer reaction. A single paper reported photoaffinity labeling of GDI with DATFP-modified Rab5 (26). On the other hand, we previously developed another photoreactive farnesyl analogue, (3-azidophenoxy)geranyl pyrophosphate (abbreviated as POG-PP), which has the photoreactive azidophenoxy group at the distal end of the structure, and created in vitro a functional (but nonmethylated) Tβγ analogue in which the farnesyl was replaced by POG (27). In the present study, we have generated the carboxyl methylated POG-Tβγ (POG-Tβγ-OMe) by utilizing the processing enzymes, FTase, Rce1, and Icmt, in order to examine the mode of molecular interaction of the POG moiety in the Tβγ analogue having the complete set of modifications at the C-terminus of Tγ.

We investigated the membrane-stabilizing effect of three synthesized polar carotenoids, thermozeaxanthin (TZ), zeaxanthin glucoside (ZG) and zeaxanthin (Z), using the fluorescent calcein-leakage measurement from the calcein-entrapped liposomes composed of dipalmitoylphosphatidylcholine (DPPC). The addition of TZ stabilized the liposomal membranes composed of DPPC at pH values ranging from 4.0 to 10.0. The addition of three carotenoids, TZ, ZG and Z, stabilized the membrane at acidic and neutral pH values ranging from 4.0 to 7.5. The values of leakage were lower at 30 °C and highest at 40 °C, and subsequently, gradually decreased at the higher temperature. The addition of TZ and Z stabilized the membranes, whereas, ZG destabilized the membranes at a temperature higher than 50 °C. In addition, the membrane-stabilizing effect of the carotenoids with the calcein-entrapped liposomes composed of lipids extracted from Thermus thermophilus were investigated. The addition of TZ resulted in stabilization of the membrane at all ranges of pH values. However, the addition of Z and ZG destabilized the membrane.

ESR measurements under tensile deformation of vulcanized rubber were carried out by the combination of homebuilt stretching machine with commercially available ESR spectrometer. The changes of radical concentrations during tensile deformation were successfully evaluated by this technique. It was found that the destruction and re-construction of crosslinking structure developed in the samples were well correlated with the changes of radical concentrations during tensile deformation. That is, the broken crosslinking structure by stretching was partly recovered in the sample crosslinked by sulfur. On the other hand, such behavior was minor in the sample crosslinked by peroxide.

電子スピン共鳴(ESR)法により加硫ゴム試料中でひずみにより発生するラジカル種の同定を行った後，架橋形態の異なる(モノスルフィド架橋，ポリスルフィド架橋および過酸化物架橋)加硫ゴム試料について，ひずみにより発生するラジカル濃度の定量化を行った．その結果，加硫促進剤に N-cyclohexyl-2-benzothiazol-sulfenamide(CZ)を用いた場合，g 値として 2.004 を有する吸収は，硫黄ラジカルと炭素ラジカルの両方が関与していること，加硫促進剤に Tetramethyl thiuram disulfide(TMTD)を用いた場合，g 値として 2.014, 2.004 を有する吸収を確認し，このうち g 値として 2.014 を有する吸収は，硫黄ラジカルのみが関与しており，炭素ラジカルと区別できることが確認された．また，架橋形態の異なる試料について印加した力学的エネルギーの増加に伴い g 値として 2.004 を有するラジカル濃度は連続的に増加し，その程度はモノスルフィド架橋>ポリスルフィド架橋>過酸化物架橋となった．これらのこととラジカルのライフタイムが加硫ゴムの力学的疲労に与える影響について検討を行った．

ゴム中におけるシリカの化学反応性ついて検討を行った．溶液混合法で得た湿式シリカ(AQ)充填ポリイソプレン(PIR)を大気中 100℃ で熱処理を行った試料について ESR 測定を行った結果，ポリエニルラジカルに基づく吸収が認められ，その吸収強度はシリカのシラノール基数とともに増大した．FT IR の測定結果から，このラジカル発生は PIR の熱分解と酸化劣化によるものであることがわかった．同種のラジカルの発生は減圧下で熱処理を行った試料においても確認されたことから，シリカが PIR の熱分解と酸化反応を促進していることが示された．AQ 存在下におけるイソブチルビニルエーテルのカチオン重合の進行が 13C NMR および FT IR 測定結果より確認され，シリカが酸触媒能を有することがわかった．しかし酸触媒の作用はイオン的であるのに対し，分子鎖の切断と再結合はラジカル反応であり，シリカが PIR の熱分解や酸化反応を促進する直接的な理由は現在のところ不明である．

液状エチレンプロピレンジエンゴム(EPDM)は，その優れた流動特性から，精密成形やインサート成形が可能であるが，固体状 EPDM に比べて機械的強度が低い欠点を有する．本研究では，液状 EPDM の機械的強度向上を目的とし，ヒドロシリル化反応を利用して架橋(ヒドロシリコーン架橋)したシリカ充てん液状 EPDM の強度特性に及ぼすシランカップリング剤の影響について検討した．シランカッ プリング剤，EPDM および架橋剤間の化学結合形成について，29Si NMR, 1H NMR および赤外吸収測定から検討した結果，液状 EPDM は架橋剤であるヒドロシリコーン化合物とシランカップリング剤を介して，シリカと結合形成していることが明らかとなり，シランカップリング剤を添加した系は，有効網目鎖密度が小さい領域において，引張強さ，引張強さと破断伸びの積(抗張積)が向上することがわかった．