21 research outputs found
Seismic exploration at Fuji volcano with active sources : The outline of the experiment and the arrival time data
Fuji volcano (altitude 3,776m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 seismic stations were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times and the later-phase arrival times at each station for each detonation were recorded as data. P-wave velocities in the surface layer were estimated from the travel time curves near the explosion points, with results of 2.5 km/s obtained for the vicinity of Fuji volcano and 4.0 km5/s elsewhere
Identification of IL-34 in teleost fish: differential expression of rainbow trout IL-34, MCSF1 and MCSF2, ligands of the MCSF receptor
11 páginas, 8 figuras, 2 tablasThe mononuclear phagocyte system is composed of monocytes, macrophages and dendritic cells and has crucial roles in inflammation, autoimmunity, infection, cancer, organ transplantation and in maintaining organismal homeostasis. Interleukin-34 (IL-34) and macrophage colony stimulating factor (MCSF), both signalling through the MCSF receptor, regulate the mononuclear phagocyte system. A single IL-34 and MCSF gene are present in tetrapods. Two types of MCSF exist in teleost fish which is resulted from teleost-wide whole genome duplication. In this report, we first identified and sequence analysed six IL-34 genes in five teleost fish, rainbow trout, fugu, Atlantic salmon, catfish and zebrafish. The fish IL-34 molecules had a higher identity within fish group but low identities to IL-34s from birds (27.2–33.8%) and mammals (22.2–31.4%). However, they grouped with tetrapod IL-34 molecules in phylogenetic tree analysis, had a similar 7 exon/6 intron gene organisation, and genes in the IL-34 loci were syntenically conserved. In addition, the regions of the four main helices, along with a critical N-glycosylation site were well conserved. Taken together these data suggest that the teleost IL-34 genes described in this report are orthologues of tetrapod IL-34.
Comparative expression study of the three trout MCSFR ligands revealed that IL-34, MCSF1 and MCSF2 are differentially expressed in tissues and cell lines. The expression of MCSF1 and MCSF2 showed great variance in different tissues and cell lines, suggesting a role in the differentiation and maintenance of specific macrophage lineages in specific locations. The relatively high levels of IL-34 expression across different tissues suggests a homeostatic role of IL-34 for the macrophage lineage in fish. One striking observation in the present study was the lack of induction of MCSF1 and MCSF2 expression but the quick induction of IL-34 expression by PAMPs and inflammatory cytokines in cell lines and primary head kidney macrophages in rainbow trout. In a parasitic proliferative kidney disease (PKD) model, the expression of IL-34 but not the dominant MCSF2 was affected by PKD, suggesting an involvement of macrophage function in this disease model. Thus IL-34 expression is sensitive to inflammatory stimuli and may regulate macrophage biology once up-regulated.TW received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). TK was supported financially by the Program “Improvement of Research Environment for Young Researchers” from the Japanese Ministry of Education, Culture, Sports, Science and Technology, a Grant-in-Aid for Young Scientists (23780199) and a grant for Scientific Research on Priority Areas from the University of Miyazaki. MMC thanks the Consejo Superior de Investigaciones Científicas (CSIC, Spain) and the Xunta de Galicia for her “Ángeles Alvariño” postdoctoral contract. Thanks to Dr. Jason Holland (Scottish Fish Immunology Research Centre, University of Aberdeen) for supplying of the PKD samples.Peer reviewe
Mechanistic Studies of Highly Enantio- and Diastereoselective Aza-Petasis–Ferrier Rearrangement Catalyzed by Chiral Phosphoric Acid
The precise mechanism of the highly <i>anti</i>- and
enantioselective aza-Petasis–Ferrier (APF) rearrangement of
hemiaminal vinyl ethers catalyzed by a chiral phosphoric acid was
investigated by undertaking experimental and theoretical studies.
The APF rearrangement is characterized by the following unique mechanistic
features: (i) efficient optical kinetic resolution of the starting
racemic hemiaminal vinyl ether, (ii) enantioconvergent process from
racemic hemiaminal vinyl ethers to optically active β-amino
aldehyde products, and (iii) anomalous temperature effects on the
enantioselectivity (enantioselectivity increases as reaction temperature
increases). The following experiments were conducted to elucidate
the unique mechanistic features as well as to uncover the overall
scheme of the present rearrangement: (A) X-ray crystallographic analysis
of the recovered hemiaminal vinyl ether to determine its absolute
configuration, (B) rearrangements of enantiomerically pure hemiaminal
vinyl ethers to validate the stereochemical relationship between the
hemiaminal vinyl ethers and β-amino aldehydes, (C) theoretical
studies on the transition states of the C–O bond cleavage and
C–C bond formation steps to gain an insight into the optical
kinetic resolution of the hemiaminal vinyl ether and the origin of
the stereoselectivity, as well as to elucidate the overall scheme
of the present rearrangement, and (D) crossover experiments of two
hemiaminal vinyl ethers having different vinyl ether and aliphatic
substituents to comprehend the mechanism of the anomalous temperature
effect and the enantioconvergent process. The results of experiments
and theoretical studies fully support the proposed mechanism of the
present <i>anti</i>- and enantioselective APF rearrangement
Cause of destructive strong ground motion within 1–2 s in Mukawa town during the 2018 Mw 6.6 Hokkaido eastern Iburi earthquake
We investigated the cause of destructive ground motion during the 2018 Hokkaido eastern Iburi earthquake. We conducted strong motion observations of aftershocks and microtremors and the surface wave method in the damaged areas of the town of Mukawa, Hokkaido prefecture, Japan. The ground accelerations were continuously recorded during a period of approximately 3 months after the main shock on September 6, 2018. The heavily damaged buildings were mainly situated around the strong motion station (HKD126) in Mukawa town. Such concentration of damage can be explained by the strong power that was observed in the 1–2 s period of the response spectrum at this station. We estimated the S-wave velocity profiles of this station site and a temporary station site that was installed on a nearby hill. The estimated S-wave velocity, which was inverted from phase velocity structures with the microtremor array and the surface wave method observations explained the difference in the SH-wave amplification characteristics between the two sites. An analysis of HKD126 and the temporarily observed records clearly indicates the strong effects of the local geological conditions on the heavily damaged area of Mukawa. The strong ground motion power generated during the main shock in Mukawa for 1–2 s period was mainly amplified by this shallow underground velocity structure
Chiral Phosphoric Acid Catalyzed Enantioselective Ring Expansion Reaction of 1,3-Dithiane Derivatives: Case Study of the Nature of Ion-Pairing Interaction
Chiral counterion
controlled asymmetric catalysis via an ion-pairing
interaction has attracted immense attention in recent years. Despite
a number of successful studies, the mechanistic elucidation of the
stereocontrolling element in the ion-pairing interaction is rarely
conducted and hence its nature is still far from being well understood.
Herein we report an in-depth mechanistic case study of a newly developed
enantioselective ring expansion reaction of 1,3-dithiane derivatives
catalyzed by chiral phosphoric acid (CPA). An unprecedented enantioselective
1,2-sulfur rearrangement/stereospecific nucleophilic addition sequence
was proven to be the stereoselective pathway. More importantly, by
thorough investigation of the intrinsic nature of the stereospecific
nucleophilic addition to the cationic thionium intermediate, we discovered
that the key interaction in this process is the nonclassical C–H···O
hydrogen bonds formed between the conjugate base of the CPA catalyst
and the cationic intermediate. These C–H···O
hydrogen bonds not only bind the catalyst to the substrates to form
energetically favored states throughout the overall processes but
also firmly maintain the relative positions of these fragments as
the “fixed” contact ion pair to sustain the chiral information
generated at the initial sulfur rearrangement step. This mechanistic
case study provides a very clear understanding of the nature of the
ion-pairing interaction in organocatalysis. The conclusion encourages
the further development of the research field with the focus to design
new organocatalysts and cultivate novel organocatalytic transformations
Perfluorinated Aryls in the Design of Chiral Brønsted Acid Catalysts: Catalysis of Enantioselective [4 + 2] Cycloadditions and Ene Reactions of Imines with Alkenes by Chiral Mono-Phosphoric Acids with Perfluoroaryls
Perfluorinated
aryl-incorporating chiral monophosphoric acids were used for highly
stereoselective reactions of <i>N</i>-acyl and <i>N</i>-acyloxy aldimines with styrenes. Their electronic and steric profiles
were established in comparison with those of phenyl, binaphthyl, and
partially fluorinated aryls. The [4 + 2] cycloaddition reactions of <i>N</i>-benzoyl aldimines with alkenes proceeded with excellent
diastereo- and enantioselectivities in the presence of the perfluorophenyl-incorporating
chiral monophosphoric acid catalysts <b>1a</b> and <b>1c</b>. The stereoselective elaboration of polysubstituted cycloadducts
to amines is described. The imino–ene reactions of <i>N</i>-Fmoc imines with alkenes have been successfully developed
in a three-component manner. This process uses aldehydes, 9-fluorenylmethyl
carbamate, and alkenes in the presence of a chiral monophosphoric
acid catalyst, <b>2a</b>, possessing an F<sub>10</sub>binaphthyl
skeleton