Initial Soil Formation Processes of Volcanogenous Regosols (Scoriacious) from Miyake-jima Island, Japan

In the initial soil formation processes of the Volcanogenous Regosols (Scoriacious) from Miyake-jima Island, Japan, the soil profile morphology showed a distinct formation of the A horizon, about 10 cm thick, over C horizons during a period of 125 years. Along with these soil formation processes under the primary succession of vegetation from bare land to mixed forest, the following changes in the soil characteristics were observed of four study sites where soil formation had occurred over a period of 16, 38, 60 and 125 years in scoriacious volcanic materials ejected during each eruption. Whole soil samples of the surface horizon showed that the proportion of the > 2mm fraction decreased and the clay fraction increased. Electron microscopic observation revealed that pores on the scoria surface were newly formed and had expanded with advanced weathering, and that the formation of a weathering zone on the scoria surface (polygonal shape) was more recognized with the passage of time. Soil pH of the surface horizon decreased, and the amount of carbon in the surface samples showed a linear increase with the passage of time. The amounts of exchangeable bases and the CEC value of the surface samples showed comparable increase rates with time. Consequently, the base saturation percentage was kept at about 100% during the 125-year period. It was suggested that the increase in the amounts of exchangeable bases was controlled by the increase in the amounts of soil organic matter accumulated during the initial soil formation processes of Volcanogenous Regosols (Scoriacious).     

Temporal and regional variability of cumulative ecological risks of pesticides in Japanese river waters for 1990–2010

We quantitatively evaluated the cumulative ecological risks from multiple pesticides used in paddy fields in Japan. Moreover, we visualized the temporal and regional variability of those risks for 1990–2010. Considering the region-specific parameters of environmental conditions, region-specific predicted environmental concentrations were estimated at 350 river-flow monitoring sites in Japan. Then the multi-substance potentially affected fraction (msPAF) was calculated as a risk index of multiple pesticides by using the computation tool NIAES-CERAP. The median msPAF values for insecticides and herbicides decreased by 92.4% and 53.1%, respectively, from 1990 to 2010. This substantial reduction in ecological risk was attributed to the development of low-risk pesticides by manufacturers, the efforts of farmers in risk reduction, and tighter regulation by the Japanese government. In particular, the substantial reduction of the ecological risk from insecticides was largely due to the decrease in the use of organophosphorus insecticides.     

Seroepizootiological survey of Japanese encephalitis virus and Getah virus in regional horse race tracks from 1991 to 1997 in Japan.

A sero-epizootiological survey was conducted for Japanese encephalitis virus (JEV) and Getah virus (GeV) at 10 to 20 regional horse race tracks from 1991 to 1997 in Japan. It was observed that geometrical mean (GM) antibody titer to JEV and GeV was 10 to 50 times higher than others at several race courses (RCs) almost every year. Of them, several race horses showing high antibody titer, which were suggested to be infected with the virus, were also observed in this survey. These data suggested that the viruses have spread among race horses almost every year in Japan, although, fortunately, no horse showing clinical illness due to these viruses was observed. The calendar years and the names of the race courses in which the spread of JEV was suggested were Sonoda and Nakatsu RCs in 1991, Nakatsu RC in 1992, Arao RC in 1993, Nagoya RC in 1994, Kaminoyama, Urawa, Saga and Arao RCs in 1995 and Ooi and Saga RCs in 1997. Spread of JEV was not observed in 1996. The calendar year and name of the race courses at which the spread of GeV was suggested were at Ooi, Sonoda and Nakatsu RCs in 1991, Arao RC in 1992, Nakatsu RC in 1994 and 1995, Funabashi RC in 1996, Saga RC in 1997. It was suggested that surveillance of JEV and GeV should be continued in the future in at least the southern to middle parts of Japan. It has also been suggested that it is necessary to promote the wider use of vaccines to persons related to horse racing.     

Notes on the Occurrence of Pathogenic Races of <Emphasis Type="Italic">Xanthomonas oryzae </Emphasis>pv. <Emphasis Type="Italic">oryzae </Emphasis>Found in Hiroshima Prefecture in 1999

The pathogenic race of 59 cultures of Xanthomonas oryzae pv. oryzae, a pathogen of bacterial leaf blight of rice, isolated from six locations in the inland mountainous area of Hiroshima Prefecture in 1999, were determined by a set of traditional differentials. Four races—I, II, V and VII—were found across the area; however, we noticed the composition of the races as well as the dominant race in each location different. All races were avirulent on differential cultivar Te-tep. Races V and VII were new to Hiroshima. The rice cultivars infected with bacterial leaf blight in Hiroshima are thought to be grouped into the Kinmaze group, which does not have any resistance genes. Apparently, a variety of races occurred unexpectedly on the cultivars contrary to stabilizing selection theory. Received 25 February 2000/ Accepted in revised form 13 July 2000     

Differences of tensile strength distribution between mechanically high-grade and low-grade Japanese larch lumber I: Effect of length on the strength of lumber

An experimental study was conducted to evaluate the effect of length on the parallel-to-grain tensile strength of Japanese larch (Larix kaempferi, Carriere) lumber. Six hundred pieces of mechanically graded lumber were tested at gauge lengths of 60, 100, and 180 cm. The lumber was sorted into matched groups according to the dynamic Young's modulus measured by the longitudinal vibration method before the lumber was cut to the particular length. The averages of the dynamic Young's modulus of high-grade (H) and low-grade (L) specimens were 12.8 and 7.5 GPa, respectively. Using nonparametric estimates, the estimated length effect parameters of H and L were 0.268 and 0.304 for the 50th percentile and 0.121 and 0.256 for the 5th percentile, respectively. We then concluded that the different length effect factors between H and L could be used when using the lumber for practical purposes. The parameters of L were larger than those for H, and the parameters for 5th percentiles were smaller than the parameters for 50th percentiles. When two-parameter Weibull distribution functions were fitted to the strength data, the estimated shape parameters of the Weibull distribution by the parametric method were almost identifical to the inverse of nonparametric parameters except the 5th percentiles for H. The influence of defects such as knots on the lower tail of the strength distribution in H may be different from that in L.Part of this paper was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998     

Differences of tensile strength distribution between mechanically high-grade and low-grade Japanese larch lumber 11: Effect of knots on tensile strength distribution

The tensile strength (TS) test results of Japanese larch (Larix kaempferi, Carriere) lumber of varying length have shown that the length effects on TS were different between high-grade (H) and low-grade (L) lumber. In this paper, we examined the effect of knots on the TS distribution by measuring the number of knots and the knot area ratio of each specimen. There were more knots in L than in H; and the knot area ratio in L distinctly increased as the length increased compared to that in H. The correlation coefficients between physical properties and TS indicated that knots were the most influencial factor for TS among several physical properties: annual ring width, distance from pith, density, dynamic Young's modulus, and knots. We attempted to estimate the length effect parameters by introducing the concept of assumed knot strength. We thought that the length effect parameters for 50th percentiles of TS could be estimated well with fitted 3P-Weibull, and that the parameters for 5th-percentiles could be estimated well with 2P-Weibull fitted to lower-tail 10% data by the likelihood method. The differences of length effect on TS between H and L should be governed by the presence of knots. The independent model based on the concept of assumed knot strength may express the TS of structural lumber of various lengths.     

Transmission of extended-spectrum cephalosporin-resistant Salmonella harboring a blaCMY-2-carrying IncA/C2 plasmid chromosomally integrated by ISEcp1 or IS26 in layer breeding chains in Japan

Dissemination of extended-spectrum cephalosporin (ESC)-resistant Salmonella is a public health concern in the egg production industry. ESC-resistant Salmonella often acquires the bla gene via insertion sequences (ISs). Therefore, this study aimed to assess antimicrobial resistance in Salmonella from Japanese layer breeding chains and egg processing chains, and determine the genetic profiles of IS-like elements in ESC-resistant Salmonella. Antimicrobial susceptibility testing was performed on 224 isolates from 49 facilities involving layer breeder farms, hatcheries, pullet-rearing farms, and layer farms in breeding chains along with egg processing chains. ESC-resistant Salmonella strains were whole-genome sequenced. Among them, 40 (17.9%) were resistant to at least streptomycin, tetracycline, ampicillin, chloramphenicol, cefpodoxime, nalidixic acid, ciprofloxacin, and/or kanamycin despite lacking resistance to azithromycin and meropenem. Moreover, 15 were ESC-resistant Salmonella harboring bla_CMY-2 (Salmonella enterica serovar Ohio, n=12; S. Braenderup, n=1; untypeable with O7:b:-, n=1) and bla_CTX-M-14 (S. Cerro, n=1). IncA/C₂ plasmids containing ISEcp1, IS26, and multiple antimicrobial resistance genes (including bla_CMY-2) were identified in S. Ohio isolates from pullet-rearing and layer farms belonging to the same company. Chromosomal integration of partial or whole IncA/C₂ plasmids was seen with two S. Ohio isolates via ISEcp1 or IS26, respectively. Antimicrobial resistance genes such as bla_CMY-2 might be transmitted among the upper and the lower levels of layer breeding chains via the replicon type IncA/C₂ plasmids containing ISEcp1 and IS26.     

Influence of inorganic matter on wood pyrolysis at gasification temperature

The influence of inorganic matter on the pyrolysis of Japanese cedar (Cryptomeria japonica) wood was studied at a gasification temperature of 800°C with demineralization through acid washing. Some influences on the formation of char, tar, and low molecular weight products coincided with results reported at temperatures lower than the gasification temperature. However, the carbonization behavior of the volatile products and the yield of polysaccharide fraction were not able to be explained as a sum of the pyrolysis of cellulose, hemicellulose, and lignin even after demineralization. These results suggest some interactions between wood constituent polymers other than the influence of inorganic matter.     

Development of a rapid and accurate PCR-based detection method for commercially valuable green algal species

We developed a rapid and accurate PCR-based inspection technique for individual detection of five commercially important green algal species, Ulva linza, U. prolifera, U. intestinalis, U. compressa and Monostroma nitidum, all of which are controlled as import quota items in Japan. This analytical method has solved the general problem of PCR-based detection methods of being defenseless against false-negatives by application of a duplex PCR technique with an internal control band generated by a set of universal primers for green algal species. Due to the detection of small-sized PCR products of <250 bp lengths, the analytical method would be useful for deeply processed products and completes its quick PCR amplification within 45 min. The validity of the developed analytical method was proved by a pre-test using a total of 129 samples (12 imported products and 31 Japanese commercial products). This analytical method is a powerful tool for screening of commercial green algal products to discover the five controlled algal species and will allow inspection authorities, including the Customs Service, to improve their examination systems in terms of simplification, rapidity and cost-effectiveness.