Effects of complex stress of chronic acid fog exposure with rhizosphere aluminum on nutrient status in Abies firma seedlings

We exposed momi fir (Abies firma Sieb. et Zucc.) seedlings to simulated acid fog of pH 3.0 for about 3 years (from July 1999). During the last year of acid fog exposure, half of the seedlings were subjected to rhizosphere Al stress (complex stress) and the nutrient status of seedlings was determined. Chronic acid fog exposure decreased Fe and Zn concentrations in current-year and 1-year needles, and Al in 1-year needles, but had little effect on major element concentrations. Aluminum treatment had a broad impact on nutrient status in fine roots and needles. In fine roots, increases in Al and Cu concentrations and decreases in B, Mn, and Zn concentrations were observed. In 1-year needles, Al treatment increased Al, B, and Mn concentrations and decreased Cu concentration. The complex effect of acid fog with aluminum on nutrient status was relatively slight. These results show that changes in nutrient status under chronic acid fog exposure and/or Al stress are induced before the decline of photosynthesis in momi fir seedlings, mainly due to Al stress.     

Effects of vegetation history on distribution of Al in surface soils of suburban forests in Aichi Prefecture, Japan

This study examined the distribution of water-extractable Al in soils from forest sites near Nagoya in Aichi Prefecture. The mean concentrations of water-extractable Al in surface soils varied markedly among sites, with the values at site FGB (126 mg/kg) higher than those at sites FG (11.8 mg/kg) and FCB (33.8 mg/kg). Comparisons of the acid buffer capacity of vegetation at the sites revealed that forest cover has a higher capacity for neutralization than the denuded state. We found that the effects of acidic accumulation in the surface soils of suburban forests might depend on vegetation history, and that forest soils that once had no vegetation cover accumulated labile Al due to acidification. The phenomenon was particularly distinct on granite bedrock.     

Alternative BSE risk assessment methodology for beef and beef offal imported into Japan

The Food Safety Commission (FSC) of Japan, established in July 2003, has its own initiative to conduct risk assessments on food stuffs known as "self-tasking assessment". Within this framework, the FSC decided to conduct a risk assessment of beef and beef offal imported into Japan from countries with no previous BSE reports; thus, a methodology was formed to suit to this purpose. This methodology was partly based on the previous assessments of Japanese domestic beef and beef imported from U.S.A./Canada, but some modifications were made. Other organizations' assessment methods, such as those used for BSE status assessment in live cattle by the OIE and EFSA's GBR, were also consulted. In this review, the authors introduce this alternative methodology, which reflects (1) the risk of live cattle in the assessed country including temporal risks of BSE invasion and domestic propagation, with the assessment results verified by surveillance data, and (2) the risk of beef and beef offal consisting of cumulative BSE risk by types of slaughtering and meat production processes implemented and the status of mechanically recovered meat production. Other possible influencing factors such as atypical BSE cases were also reviewed. The key characteristic of the current assessment is a combination of the time-sequential risk level of live cattle and qualitative risk level of meat production at present in an assessed country.     

Spatial variations in nitrous oxide and nitric oxide emission potential on a slope of Japanese cedar (Cryptomeria japonica) forest

To quantify the spatial variation and spatial structure of nitrous oxide (N₂O) and nitric oxide (NO) emission from forest soils, we measured N₂O and NO emission rates from surface soil cores taken at 1 m intervals on a cross-line transect (65 m × 20 m) on a slope of Japanese cedar ( Cryptomeria japonica ) forest in a temperate region of central Japan and analyzed the spatial dependency of N oxide gas emissions using geostatistics. We divided N₂O emission into N₂O from denitrification and N₂O from nitrification using the acetylene inhibition method. According to the geostatistical analysis, N₂O emission rates on the slope had large spatial variation and weak spatial dependency. This weak spatial dependency was caused by the inordinately high N₂O emissions on the slope, which were derived mainly from denitrification. In contrast, NO emission rate on the slope had large spatial variation, but strong spatial dependency and a distinct spatial distribution related to slope position, that is, high in the middle of the slope and low in the shoulder and the foot of the slope. The CN ratio and water-filled pore space were the dominant factors controlling NO emission rate on a slope. Our results suggest that spatial information about topographic factors helps to improve the estimation of both N₂O emission and NO emission from forest soils.     

Molecular cloning, nucleotide sequence and characteristics of a xylanase gene (xynA) from Ruminococcus albus 7

A 2.6-kb DNA fragment encoding a xylanase gene ( xyn A) was cloned from the rumen hemicellulolytic bacterium Ruminococcus albus 7. The deduced primary structure of the protein (XynA) was divided into a signal peptide region and 3 domains. Domain A was identified as a family 11 (G) catalytic domain, but one amino acid residue was replaced by another in an active site signature 1 of family 11. Domain B is a stabilizing domain for the catalytic domains of families 10 and 11. Deletion of domain B reduced stability of the xylanase at high temperature and at high and low pH. Domain B may be useful for protein engineering of xylanase. Domain C has sequence similarity to deacetylases and NodB proteins.     

Difference in response to aluminum among Japanese coniferous species

Seedlings of Chamaecyparis obtusa, Cryptomeria japonica D. Don, and Abies firma Sieb. et Zucco were grown hydroponically for 4 weeks in the presence or absence of aluminum (Al) and with or without reduced pH. Under exposure to AI, root and shoot growth of C. obtusa was enhanced. A. firma showed the same tendency as C. obtusa, though not significantly. Only in C. japonica, growth was reduced with Al, especially shoot growth. In all the species, callose production in the root tips was observed in the presence of Al. A positive correlation was observed between the relative root callose content and relative root growth (r = 0.83), and significant root elongation with AI treatment was observed in all the species. Therefore, it is considered that callose deposition in the root tips of these species may not indicate the Al-induced root cell injury causing root growth inhibition. The highest callose content in the root tip and strong callose fluorescence in the epidermis and zones of cell contact were observed in C. obtusa. Since the Al translocation rate from roots to leaves was the lowest in C. obtusa and since significant growth enhancement was observed in the presence of Al, it is possible that the accumulation of callose in the root epidermis and in the zones of cell contact is related to Al-resistance in C. obtusa.     

Molecular species of collagen in muscular and vertebral parts of white sturgeon Acipenser transmontanus

The molecular species of collagen in the muscular and vertebral parts of white sturgeon Acipenser transmontanus were examined by biochemical techniques. Pepsin-solubilized collagens were prepared from these parts, and fractionated into major and minor collagen fractions by differential salt precipitation at acidic or neutral pH. Collagens contained in these fractions showed several features characteristic of fish type I and V collagens, respectively, in SDS-PAGE patterns and the amino acid compositions of both parts. These results suggest that at least two molecular species, corresponding to type I and V collagens, are distributed in the muscular and vertebral parts of white sturgeon.     

Bacterial communities are more dependent on soil type than fertilizer type, but the reverse is true for fungal communities

The soil microbial community is strongly influenced by a wide variety of factors, such as soil characteristics and field management systems. In order to use biological indicators based on microbial community structure, it is very important to know whether or not these factors can be controlled. The present study aimed to determine whether soil type or fertilization has a greater influence on the soil microbial community based on denaturing gradient gel electrophoresis (DGGE) analysis of 12 experimental field plots containing four different soil types, Cumulic Andosol, Low-humic Andosol, Yellow Soil and Gray Lowland Soil, kept under three different fertilizer management systems since 2001 (the application of chemical fertilizer, the application of rice husk and cow manure, and the application of pig manure). Bacterial DGGE analysis using 16S rRNA genes and fungal DGGE analysis using 18S rRNA genes revealed that the bacterial community was related to the soil type more than the fertilization; however, the fungal community was related to the fertilization more than the soil type. These results might suggest that the fungal community is easier to control by fertilization than the bacterial community. Thus, we propose that indicators based on the fungal community might be more suitable as microbial indicators for soil quality.