Western Part Of Japan Research Articles

Case Study of the Storm Surges in the Seto Inland Sea Caused by Typhoon Chaba

Typhoon Chaba hit southeastern Kyushu and passed through Chugoku (western part of Japan's main island) on August 30, 2004, causing large storm surges in the Seto Inland Sea (SIS). Record-high storm tides were recorded at tide stations in Takamatsu and Uno Ports. We analyzed the tidal data and simulated this case with numerical storm surge models. The results revealed that the wind setup basically played a key role in causing the large storm surges. Since the time of the maximum storm surge (MSS) approximately corresponded to the time of high spring tide in Takamatsu, a record-breaking storm tide was observed there. However, the MSS occurred not when the typhoon was closest to the city but two hours later. We also investigated the mechanism and the degrees of contribution of the two main factors of storm surges, the inverse barometer effect and the wind setup, in each local area. The results revealed that the peak time of each effect was influenced by geographical features, as well as the wind field and the typhoon position, and had different characteristics in these areas. They also revealed that the Kanmon Strait, which is very narrow and supposed to be negligible in effect, had an important role in sea water inflow into the SIS.

A survey method for evaluating drought-sensitive bryophytes in fragmented forests: A bryophyte life-form based approach

Drought-sensitive bryophytes are especially vulnerable to edge effects caused by forest fragmentation. Because of increased forest fragmentation, these bryophyte species are declining and are in need of conservation. Considering that a field survey including all bryophyte species is very time consuming, methods that make identification less difficult should be tested for their usefulness in conservation. This paper describes an alternative survey method that utilizes the correlation between bryophyte life-forms and microclimates for evaluating drought-sensitive bryophytes. This survey method was examined using epiphytic bryophyte flora on tree trunks in 27 fragmented forests of Kyoto city, in the western part of Japan. The usefulness of life-forms for this evaluation was discussed based on the correlation of life-forms with species richness and microclimates. The results indicated that, while life-from richness was considered to reflect the heterogeneity of moisture availability and light intensity in bryophyte habitats, a certain life-form category (for example, fans and dendroids) seemed to correlate with drought sensitivity of bryophytes. Considering this correlation, an alternative survey method was proposed that utilizes the richness of hygrophilous life-forms. This survey method seems to be more cost-effective than a traditional all-species survey, and provides an important step toward the conservation of drought-sensitive species.

AAC(6′)-Iaf, a Novel Aminoglycoside 6′- N -Acetyltransferase from Multidrug-Resistant Pseudomonas aeruginosa Clinical Isolates

We report here the characterization of a novel aminoglycoside resistance gene, aac(6')-Iaf, present in two multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates. These isolates, IMCJ798 and IMCJ799, were independently obtained from two patients, one with a urinary tract infection and the other with a decubitus ulcer, in a hospital located in the western part of Japan. Although the antibiotic resistance profiles of IMCJ798 and IMCJ799 were similar to that of MDR P. aeruginosa IMCJ2.S1, which caused outbreaks in the eastern part of Japan, the pulsed-field gel electrophoresis patterns for these isolates were different from that for IMCJ2.S1. Both IMCJ798 and IMCJ799 were found to contain a novel chromosomal class 1 integron, In123, which included aac(6')-Iaf as the first cassette gene. The encoded protein, AAC(6')-Iaf, was found to consist of 183 amino acids, with 91 and 87% identity to AAC(6')-Iq and AAC(6')-Im, respectively. IMCJ798, IMCJ799, and Escherichia coli transformants carrying a plasmid containing the aac(6')-Iaf gene and its upstream region were highly resistant to amikacin, dibekacin, and kanamycin but not to gentamicin. The production of AAC(6')-Iaf in these strains was confirmed by Western blot analysis. Thin-layer chromatography indicated that AAC(6')-Iaf is a functional acetyltransferase that specifically modifies the amino groups at the 6' positions of aminoglycosides. Collectively, these findings indicate that AAC(6')-Iaf contributes to aminoglycoside resistance.

Prevalence of Spinocerebellar Degenerations in the Hokuriku District in Japan

Background: The prevalence of disease subtypes of spinocerebellar degenerations (SCDs) varies between countries, and even between areas within a country. We report unprecedented epidemiologic data on SCDs in the Hokuriku district, which is located in the central, western part of Japan. Methods: Clinical and genetic data on SCD patients were obtained via questionnaires distributed to all the departments of neurology, psychiatry and internal medicine in the Hokuriku district (n = 418). Results: Among the SCD patients, autosomal dominant cerebellar ataxias (ADCAs) were noted in 40.4%, multiple system atrophy in 24.7%, cortical cerebellar atrophy in 13.3% and autosomal recessive cerebellar ataxia in 0.3%. Genetically confirmed ADCA patients included those with Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3; 63.3%), SCA6 (20.0%), ADCA linked to chromosome 16q22.1 (10.0%), dentatorubral pallidoluysian atrophy (4.4%), SCA1 (1.1%) and SCA2 (1.1%). MJD/SCA3 was highly prevalent in the Toyama prefecture of the Hokuriku district, accounting for 90% of genetically confirmed ADCAs by birthplace; MJD/SCA3 patients were concentrated in the Gosei area, the western part of the Toyama prefecture, giving an estimated prevalence of 19.1 per 100,000 inhabitants. Conclusions: The Hokuriku district, especially the Gosei area of Toyama, had a surprisingly high relative frequency and prevalence of MJD/SCA3, which is comparable to that in the Azores, Portugal.

Duration of Maternally Derived Antibodies against Akabane Virus in Calves: Survival Analysis

To prevent encephalomyelitis caused by Akabane virus, as observed in 2006, vaccination of calves is one of the most effective prophylactic measures. For vaccination of calves, the duration of the maternal antibodies need to be considered because these antibodies are an obstacle to the effectiveness of the vaccine. In order to estimate the age of antibody decay in calves and to find factors influencing the duration of passive immunity, we conducted survival analysis using data from nationwide sentinel surveillance for Akabane disease. The accelerated failure time model based on the presence of interval censored data was used. The best fit model with a log-logistic distribution indicated that the maternal antibodies of beef calves last 1.11 times longer (95% confidence interval [CI]=1.06-1.16) than those of dairy calves. Calves in the western part of Japan and on Kyushu island, Japan, maintained the maternal antibodies 1.17 times (95% CI=1.11-1.23 and 1.10-1.24, respectively) longer than those in the eastern part of Japan. The ages at which beef calves in the eastern part of Japan, western part of Japan and Kyushu loose the antibodies, with 90% probability, were estimated to be 4.1, 4.8 and 4.8 months, respectively, while the ages were 3.7, 4.3 and 4.3 months for dairy calves in the same regions. The duration of maternal immunity to Akabane virus was different for different types of cattle and among different regions. These differences need to be taken into account when a vaccination strategy is adopted for preventing epizootic encephalomyelitis in the future.

ヌカカが媒介する家畜のアルボウイルス

Arboviruses transmitted by Culicoides biting midges cause domestic animal diseases such as congenital abnormalities and acute febrile illnesses in ruminants. Epidemics of these arboviruses, Akabane, Aino, Chuzan and Ibaraki viruses, have been frequently reported in the western part of Japan and have brought great economical damage to the livestock industry. These arboviruses are most frequently isolated from Culicoides oxystoma Kieffer in the southern part of Japan, indicating that this species acts an important vector for transmission of these viruses. However, several outbreaks have occurred in the northern regions where C. oxystoma has not been previously observed, suggesting the existence of other vector species. Recently, several arboviruses distributed in tropical and sub-tropical regions such as the Peaton, Sathuperi and Shamonda viruses were newly isolated in Japan. Several clinical cases imply these viruses are related to congenital abnormalities in cattle. Global warming is expected to expand the range of arboviruses to higher latitudes because of the brisk activities of the vectors. Therefore, we should provide integrated surveillance systems, sophisticated diagnostic measures and effective prevention strategies to combat the threats of arbovirus infections.

Outage Rates of Power Distribution Lines due to Summer and Winter Lightning in Chugoku Region

Taking the densities of lightning strokes and electric poles into account, we calculated outage rates of each equipment on a 6.6kV distribution line due to summer (Mar.-Oct.) and winter (Nov.-Feb.) lightning for 6 years in the Chugoku region located in the western part of Japan. Furthermore, using these results, we proposed some application maps for the lightning risk assessment of power distribution lines in this region considering the effect of seasonal lightning hazard.

地下構造モデルと強震動シミュレーション

The Japan islands are in a complex tectonic setting with various subducting plates, and most of urban areas are located over large-scale sedimentary basins. Since the sediments filling basins amplify ground motions and their velocity structures complicate the propagation of seismic waves, it is important for the prediction of strong ground motion and seismic hazard to determine the three-dimensional (3-D) velocity structures of these urban basins. This importance motivated various organizations to carry out extensive geophysical experiments and geological investigations, and velocity structure models are being constructed all over Japan. We have already proposed a standard procedure for modeling a regional 3-D velocity structure in Japan, simultaneously and sequentially using various kinds of datasets such as the extensive refraction/ reflection experiments, gravity surveys, surface geology, borehole logging data, microtremor surveys, and earthquake ground motion records. We applied the procedure to the Tokyo metropolitan area for constructing a reference 3-D velocity structure model. As this application confirmed the validity of the standard procedure, it is then applied to the central, eastern, and western parts of Japan in 2006 to 2008, to construct the Japan Integrated Velocity Structure Model. The velocity structure and source modelings have been dramatically improved after the 1995 Kobe earthquake with the advance of ground motion simulations based on substantial data of strong motion observation. The quality of broadband ground motion simulations enable us to predict realistic strong ground motions. The National Seismic Hazard Maps released in 2005 as a result of comprehensive research on long-term evaluation of earthquake occurrence and strong ground motion prediction are expected to be proved useful in earthquake disaster mitigation and scientific outreach to the public. It is also quite important for the simulation of long-period ground motion and its seismic hazard to validate the three-dimensional (3-D) velocity structure for the whole Japan islands. Since we are threatened by future earthquakes whose probabilities of occurrence are estimated to be high in long-term evaluation, long-period ground motions from future Tokai, Tonankai, Nankai, and Miyagi-oki earthquakes and their response spectra will be computed by using this Japan Integrated Velocity Structure Model, and combined into the Long-Period Ground Motion Hazard Maps in 2009 and later by the Headquarters for Earthquake Research Promotion. These hazard maps for the megathrust earthquakes may be proved to be touchstones of strong motion seismology.

Dental characteristics of Tohoku residents in Japan: implications for biological affinity with ancient Emishi

The population history of Japan has been widely interpreted in terms of an original Jomon occupation from the Neolithic period followed by admixture with Yayoi immigrants associated with the spread of rice farming agriculture from western Japan. According to this perspective, the people in areas remote from the western mainland island of Honshu, Japan would be less affected by the genes of immigrants. This article uses metric and nonmetric dental data to examine the genetic influence of immigrants among the early modern Edo and modern residents in the Tohoku district of northeastern Honshu. The results of these dental-trait analyses suggest a smaller gene flow of immigrants in Tohoku people, as compared to contemporary Japanese in the central and western parts of Japan. The metric dental data imply the gene flow from the west to the north was still due mainly to the males even in recent times. The findings of some Jomon features in the late historic and modern Tohoku tooth samples support the speculation that the ancient inhabitants of this region, in the past referred to as ‘Emishi’, are people who still have preserved genetic traits of the indigenous people.

Evidence for fish cultivation during the Yayoi Period in western Japan

AbstractPeople in the western part of Japan, where the cyprinid fish fauna is very rich, have utilised these fish as a protein resource since the Jomon Period. Abundant cyprinid fish remains have been recovered from archeological sites in western Japan dating from both the Jomon (ca. 12,000 BC–300 BC) and subsequent Yayoi (ca 300 BC–AD 300) times. They captured larger cyprinids, especially Cyprinus carpio and Carassius spp., coming inshore for spawning and processed them as a food stock. One can easily imagine that people who captured cyprinids during the spawning season might also have begun to cultivate those fish sometime during prehistory, but until now there has been no evidence of fish cultivation in ancient Japan. We examined cyprinid pharyngeal tooth remains recovered from an archeological site of the Yayoi Period, the Asahi site in the Nobi Plain near Nagoya. The common carp Cyprinus carpio accounted for more than two‐thirds of the recovered pharyngeal tooth remains. There are two peaks in the body length distribution, estimated from tooth size, of common carp from this site, one at 350–450 mm and the other, higher peak at 50–150 mm. We believe that the smaller fish of 50–150 mm in body length were cultivated, because it is very difficult to capture common carp of this size in substantial numbers in the field. We propose that fish cultivation started as a by‐product of the artificial control of water levels in the paddy fields used for rice agriculture, which were characteristic of the Yayoi Period in Japan. Copyright © 2008 John Wiley & Sons, Ltd.

Spurious annual vertical deformations over Japan due to mismodelling of tropospheric delays

SUMMARY We quantitatively estimate the spurious annual vertical deformations due to the mismodelling of tropospheric delays over Japan, through a numerical simulation. For this purpose, we simulate the GPS data for present-day satellite distributions, using realistic cumulative tropospheric delays that are calculated using ray tracing and numerical weather models. To obtain the spurious deformations, the simulated GPS data are then analysed by using the same GPS processing software and the same analysis strategies as those used in the analysis of the observed GPS data. In the estimated spurious annual vertical deformations, it is found that the amplitudes of the deformations increase toward the north, reaching up to 3 mm at around 45 ◦ N, whereas the phase lags are uniform throughout Japan and vary by around 220 ◦ , indicating spurious subsidence in the middle of February. In the western part of Japan, the observed annual vertical deformations are less affected by spurious annual vertical deformations and more likely caused by the atmospheric and oceanic loading. In the northern part of Japan, we observe large (up to 8 mm) annual vertical deformations with phase lags corresponding to subsidence in winter; subsidence in winter is interpreted to be the effect of snow loading. However, some part of the observed subsidence is found to be spurious due to the mismodelling of the tropospheric delays. These spurious signals may be mitigated by using mapping functions that are constructed by using direct ray tracing and numerical weather models in the GPS analysis.

Development and characterization of 10 microsatellite markers for the semi‐evergreen tree species, Ligustrum ovalifolium (Oleaceae)

Ligustrum ovalifolium is a semi-evergreen tree distributed in the western part of Japan and southern Korea. This species contains an insular endemic variety, L. ovalifolium var. pacificum; this variety occurs only on the Izu Islands located south of the Japanese mainland Honshu. We isolated 10 polymorphic microsatellite loci from the species, and characterized them for 21 individuals from a population of L. ovalifolium. The primers developed in this study yielded an average 12.2 alleles per locus and an average expected heterozygosity of 0.78. These markers will be powerful tools for studying the genetic differentiation within the species.

Effect of nitrogen application at anthesis on Fusarium head blight and mycotoxin accumulation in breadmaking wheat in the western part of Japan

In the western part of Japan, two wheat cultivars, Nishinokaori and Minaminokaori, are currently cultivated for breadmaking. Breadmaking wheat requires a higher protein content compared to the Japanese noodle wheat (the major type of wheat in Japan). This high protein level in the grain is obtained by top-dressing with nitrogen (N) near anthesis. Because such N applications may increase levels of Fusarium head blight (FHB) and consequent mycotoxin [deoxynivalenol (DON) and nivalenol (NIV)] accumulation in the grain, the effect of N application (0, 4, and 8 g/m2) at anthesis on FHB and mycotoxin accumulation in Nishinokaori and Minaminokaori was tested in the greenhouse in 2004 and 2005 and in two fields in 2006. In the greenhouse, plants were spray inoculated at 3, 10, and 20 days after N treatment. In field experiments, colonized maize kernels, which generate ascospores during the testing season, served as inoculum. In all experiments for both cultivars, N application at anthesis significantly increased grain protein as expected, but had no significant effect on FHB and DON and NIV levels in grain. These results suggest that, at least in these cultivars, N can be applied close to anthesis without increasing the risk of FHB and mycotoxin (DON and NIV) accumulation.

Novel Human Adenovirus Causing Nosocomial Epidemic Keratoconjunctivitis

In 2000, we encountered cases of nosocomial infections with epidemic keratoconjunctivitis (EKC) at a university hospital in Kobe, in the western part of Japan. Two human adenovirus (HAdV) strains, Kobe-H and Kobe-S, were isolated from patients with nosocomial EKC infection. They were untypeable by existing neutralizing antisera; however, the isolate was neutralized with homologous antisera. We then encountered several cases of EKC due to nosocomial infections in eye clinics in different parts of Japan. A total of 80 HAdVs were isolated from patients with EKC at eight different hospitals. The partial hexon gene sequences of the isolates were determined and compared to those of the prototype strains of 51 serotypes. All isolates had identical partial hexon nucleotide sequences. Phylogenetic analysis classified these isolates into species of HAdV-D. The isolates showed 93.9 to 96.7% nucleotide identity with HAdV-D prototype strains, while all 32 HAdV-D prototype strains ranged from 93.2 to 99.2% identity. The sequences of the loop 2 and fiber knob regions from the representative strain, Kobe-H, were dissimilar in all prototype strains of 51 serotypes. We believe that this virus is a novel serotype of HAdV that causes EKC.

PIXE ANALYSIS OF ATMOSPHERIC AEROSOLS FROM ASIAN CONTINENT

A large amount of yellow sand dust from Asian continent transported to Japan by air, affecting traffic, climate and human health. The yellow sand is known as a natural phenomenon, but it is mixed with anthropogenic aerosols over the industrial area in East Asia and causes environmental pollution. In addition, atmospheric turbid phenomena are occasionally observed in spring of recent years over western part of Japan. This phenomenon is caused by the increase in the amounts of fine particles. For a better comprehension of such turbid phenomena, we collected aerosols at Nagasaki. At the same time, particle number concentrations were observed by OPC. The samples were analyzed by an in-air PIXE system at Tohoku University. Time series of elemental concentrations and particle number concentration were obtained. It found that the yellow sand dust phenomenon occurred when coarse particles reached high concentrations, and elemental concentrations of Si, Ca, Fe, Pb and Hg showed similar variations along with that of coarse particles. On the other hand, when fumes or mists were observed, concentrations of fine particles were also correlated with concentrations of S and Zn.

Refinement of a locus for autosomal dominant hereditary motor and sensory neuropathy with proximal dominancy (HMSN-P) and genetic heterogeneity

Hereditary motor and sensory neuropathy with proximal dominancy (HMSN-P) is an adult-onset peripheral neurodegenerative disorder which has been reported only in the Okinawa Islands, Japan. The disease locus of "Okinawa-type" HMSN-P has been previously mapped to 3q13.1, with all affected individuals sharing an identical haplotype around the locus, suggesting that the undiscovered causative mutation in HMSN-P originated from a single founder. We have newly found two large families from the western part of Japan within which multiple members developed symptoms similar to those exhibited by HMSN-P patients from Okinawa, with no record of affinal connection between the islands. Using these pedigrees with "Kansai-type" HMSN-P, we carried out a linkage study utilizing eight microsatellite markers and identified a candidate region on 3q13.1 cosegregating with the disease (maximum two-point LOD score of 8.44 at theta=0.0) overlapping with the Okinawa-type HMSN-P locus. However, the disease haplotype shared among all affected members in these families was different from that in the Okinawa kindred, suggesting allelic heterogeneity. Such allelic variation should aid in the identification of the disease-causative gene. Moreover, the allelic heterogeneity of HMSN-P in the Japanese population suggests that HMSN-P may be more common across other ethnic groups, but classified into other disease categories.

西日本におけるムギ類赤かび病菌Ｆｕｓａｒｉｕｍ ｇｒａｍｉｎｅａｒｕｍ種複合体のかび毒産生能と病原力

Isolates of a Fusarium graminearum species complex causing Fusarium head blight on wheat and barley were collected from the western part of Japan in 2002, and their mycotoxin productivity on a rice medium for deoxynivalenol (DON), nivalenol (NIV), T-2 toxin and zearalenone (ZEA) was examined using liquid chromatography/mass spectrometry. Fifty-eight percent of the isolates produced more NIV than DON; none of the isolates produced T-2 toxin and 96% produced ZEA. Among nine selected NIV-producing isolates, eight were significantly more virulent than isolate H-3 of a highly virulent DON chemotype, and all the NIV-producing isolates produced NIV in wheat grains obtained from a field inoculation test.

Plankton community structure and trophic interactions in a shallow and eutrophic estuarine system, Ariake Sound, Japan

Ariake Sound is a shallow, eutrophic estuarine system, located in the western part of Japan. We conducted field surveys and experiments in late autumn in 2002, 2003 and 2004 to clarify plankton community structure and trophic interactions in this system. A large photosynthetic dinofla- gellate (Akashiwo sanguinea) was persistent and the dominant phytoplankton species in all years. Diatoms and other photosynthetic flagellates were relatively minor components of the assemblage. The growth of photosynthetic flagellates such as Prorocentrum micans and cryptophycean flagellates under nutrient-enriched conditions was almost balanced with the grazing losses caused by a micro- zooplankton population dominated by protozoans, rotifers and cyclopoid copepods. Thus, P. micans and cryptophycean flagellates could not propagate their populations in the field. Diatoms had high potential growth rates and were subjected to low grazing pressure by the micro- and mesozooplank- ton. However, diatom growth was severely limited by light in this highly turbid estuarine system, and light limitation probably prevented diatoms from becoming dominant. A. sanguinea was grazed on by the ciliate Tiarina fusus, but the growth rates of A. sanguinea exceeded grazing losses by T. fusus; other zooplankton species did not graze on this dinoflagellate effectively. A. sanguinea accumulated at the surface layer in the turbid water during daytime, and thus could utilize light effectively. Low grazing pressure by zooplankton and avoidance of light limitation seem to have led to the persistent dominance of A. sanguinea, even though the potential growth rate of this species is moderate to low.

Changes in tidal currents in the ariake sound due to reclamation

The Ariake Sound is a highly productive estuary located in the western part of Japan. The decline in fisheries and the frequent occurrence of red tides and hypoxia indicate a deterioration in the ecosystem of the sound. A change in tidal currents, which is one of the possible causes of the deterioration, was investigated by numerical experiments. Two major changes in the topography of the sound, which may have changed the tidal currents, are examined. These are the reclamation in the innermost part of the sound and the construction of a dyke in a subembayment called Isahaya Bay. The numerical experiments show that the reclamation caused the tidal currents to decrease by more than 10% over a large area in the innermost part of the sound. The influence of the dyke on the tidal currents is relatively local compared to the reclamation; the area where tidal currents significantly decrease is located mostly in the subembayment.

Detection of tetrodotoxin (TTX) from two copepods infecting the grass puffer Takifugu niphobles: TTX attracting the parasites?

In May 2002, two parasitic copepods, Pseudocaligus fugu and Taeniacanthus sp., were collected from the body surface and gill of the grass puffer Takifugu niphobles, respectively, in Takehara city, Hiroshima Prefecture, faced with Seto Inland Sea located in the western part of Japan. To them was added 5 ml of 0.1% acetic acid, then the suspension was subjected to ultrasonic disruption with an ultrasonicator for 10 min. The resulting mixture was heated in a boiling water bath for 10 min, and then centrifuged. The supernatant was concentrated under reduced pressure, and loaded on to a Sep-Pak plus C18 Environmental Cartridge (Waters). The unbound fraction was analyzed by HPLC and gas chromatography–mass spectrometry (GC–MS) for tetrodotoxin (TTX). It was rather unexpectedly revealed from these results that this fraction was comprised of TTX and its analogues. As far as we know, this is the first record to show the existence of TTX in the copepods. In addition, relationships between the more and less than the average number of the two parasites and the toxicity of its skin mucus of the host were examined by student's t-test. In P. fugu, the average number per host was 13.9, and those are 520.7 ( n=9) and 269.0 MU/g ( n=22), respectively. A highly significant difference between them was detected at p-value 0.0011. In contrast, as for Taeniacanthus sp., the average number was 2.7, and those were 338.0 ( n=14) and 345.5 MU/g ( n=17), respectively. No significant difference was detected in Taeniacanthus sp. The high host-specificity of P. fugu on the toxic puffer and the present bioassay of its skin mucus suggest a possibility that TTXs may attract the parasite.