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.     

Decontamination of Cs from Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) via kraft cooking

To investigate the possibility of decontaminating ¹³⁷Cs-contaminated Cryptomeria japonica wood, kraft pulping was conducted and the Cs behavior in the reaction process was examined. ¹³³Cs-treated or ¹³⁷Cs-contaminated bark, sapwood, and heartwood chips of Cryptomeria japonica were digested using an aqueous solution of NaOH and Na₂S. The pulp was washed with ultrapure water and filtered, after which the filtrate (black liquor) was collected. The black liquor was acidified to separate the supernatant and precipitation. The Cs (¹³³Cs and ¹³⁷Cs) concentrations in the chip and reaction products were measured. As for wood samples, the majority of Cs was present in black liquor, while only a minor amount of Cs was retained in the pulp (<1%). In the case of bark, although the majority of Cs was present in the black liquor, the proportion of Cs in the pulp was much higher than that in the wood pulp. In addition, the Cs in the precipitation of the bark was higher than that in the wood, possibly because the Cs in the bark was combined with some components, which is insoluble in alkaline solution. Our results suggest that ¹³⁷Cs-contaminated Cryptomeria japonica wood can be used in the pulp and paper industries.     

Mechanism of mercerization revealed by X-ray diffraction

We studied the crystalline conversion of cellulose fiber from cellulose I to cellulose II (mercerization) by X-ray diffraction, focusing on the putative chain-polarity conversion from parallel to antiparallel. The structural change of Na-cellulose was examined during stepwise changes in NaOH concentration. Either Na-cellulose I or Na-cellulose II was formed depending on the initial NaOH concentration. Once formed, both structures were stable and did not inter-convert to each other when the NaOH concentration was changed. Such stability indicates that the parallel-to-antiparallel conversion is not likely to take place in the crystalline region of Na-cellulose. Regeneration of cellulose II from both forms of alkali cellulose proceeded with the formation of 0.44 nm lattice plane corresponding to the sheet of (1 ¯1 0) plane of cellulose II, showing that the molecular stacking due to van der Waals' interaction is the driving force of the formation of cellulose II. A mechanism was proposed whereby the geometry of the cellulose molecule allows close fitting of the hydrophobic faces only in the antiparallel arrangement, thus driving formation of the antiparallel structure of cellulose II.This study was presented in part at the 47th Annual Meeting of the Japan Wood Research Society, Kochi, April 1997; and at the 6th Annual Meeting of the Cellulose Society of Japan, Tokyo, June 1999     

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.     

Cesium absorption through bark of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

Absorption of radiocesium (¹³⁷Cs and ¹³⁴Cs) through bark, and its subsequent translocation into wood and needles, has been suggested as a potential source of tree contamination, but the process is not well understood. Field experiments were conducted to confirm whether Cs could enter a Japanese cedar tree through the bark and how Cs moves within a tree. Stable Cs (¹³³Cs) was applied to the bark at 1.2-m height on 10- and 26-year-old Japanese cedars. The ¹³³Cs concentrations were determined in the bark, sapwood, and heartwood (for 26-year-old cedar only) of stem disks from several heights, as well as in current-year needles from the canopy. The ¹³³Cs concentrations were considerably higher in the sapwood and heartwood of stem disks from 1.2-m height in treated trees than in untreated trees, suggesting that ¹³³Cs penetrated the bark to enter the wood. The average ¹³³Cs concentrations were higher in the heartwood than the sapwood, indicating ¹³³Cs accumulation in the heartwood. High ¹³³Cs concentrations in the needles of treated trees implied acropetal movement of ¹³³Cs to actively growing organs. Our results demonstrate that Cs can enter Japanese cedar trees through the bark and that Cs is transported radially to the heartwood and vertically to the apex.     

Determination of optimal time for mating by artificial insemination with chilled semen using luteinizing hormone surge as an indicator in beagles.

Artificial insemination (AI) was conducted using the second fraction of semen, which was collected from 15 male dogs, diluted to a total sperm count of 100x10(6) for each insemination with egg-yolk Tris (eyT) citrate acid buffer and incubated at 4 degrees C for 48 hours. Luteinizing hormone (LH) surge was detected to determine the optimal time for mating using canine LH assay kits. Artificial insemination using 100x10(6) sperm was performed on the fourth and sixth days or the fifth and seventh days after the LH surge. The conception rates were 33% (4/12) and 89% (8/9), respectively; the whelping rates also showed similar results. Serum LH and follicle stimulating hormone (FSH) concentrations were measured in nine dogs, and the mean LH concentration (+/- standard deviation) at LH surge was 15.77+/-7.66 ng/ml. The time of the LH surge detected by the canine LH assay kit was very similar to that measured by radioimmunoassay (RIA).     

Effect of fructo‐oligosaccharide on nitrogen utilization in guinea pigs

The present study was conducted to determine the effects of fructo‐oligosaccharide (FOS) on the nitrogen (N) utilization and digestibilities of dietary nutrients through cecotrophy in guinea pigs. Adult male guinea pigs that were housed or not housed in wooden frames to prevent cecotrophy were fed a commercial pellet diet (50 g/day) with 3% and 5% glucose or FOS for 8 days in individual metabolism cages. In the guinea pigs allowed cecotrophy, addition of FOS to the diet had no significant effects on body weight gain or apparent digestibility of N, but showed significantly lower value for the urinary N excretion and acid‐detergent fiber digestibility (P < 0.05 and P < 0.01, respectively) and significantly higher value for N retention and the N retention rate (P < 0.05). In the guinea pigs prevented from cecotrophy, FOS had no effect on N retention, but showed tendencies toward a higher value for fecal N excretion and a lower value for urinary N excretion. These results suggest that FOS stimulates cecal microbial proliferation, thereby improving N utilization in guinea pigs.     

Dietary Bacillus subtilis C-3102 Supplementation Enhances the Exclusion of Salmonella enterica from Chickens

Among the reported probiotic Bacillus strains, B. subtilis C-3102 has the unique potential to improve feed uptake under stress conditions in the broilers, piglets, and cows. In this study, we sought to evaluate the protective effect of feed additive probiotic Bacillus subtilis C-3102 against Salmonella enterica infection of specific pathogen-free (SPF) chicks in floor pens in two experiments. In the experiment-1, the chicks in the control group (n=32) were fed a basal diet and those in the C-3102 group (n=32) were fed a basal diet supplemented with 1×10⁶ CFU/g of feed for 28 days. On day 7 post-challenge with S. enterica, there was no significant change in the body weight between both the groups throughout the test period, whereas detection rates of S. enterica in the C-3102 group were significantly lower in the cecum and liver on days 21 and 14 post-challenge, respectively. In the experiment-2, minimum dosage of C-3102 cells required to protect Salmonella infection was evaluated using 3 dosages. Chicks were divided into four groups, fed with different dosages of C-3102 (1×10⁶, 5×10⁵, 3×10⁵, and 0 CFU/g of feed), and challenged with S. enterica (2.8×10⁸ CFU/chicken). S. enterica infection was completed within 7 days post- challenge and was almost excluded from the liver and spleen on day 21 post- challenge in the control group. Average values showed a trend for higher infection rates in the control group >3×10⁵>5×10⁵>1×10⁶ CFU/g on days 14 and 21 post-challenge. These results suggest that B. subtilis C-3102 supplementation has the potential to reduce S. enterica infection rates and/or to accelerate the exclusion of S. enterica from the chicks.     

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.