Effect of added organic matter on soil fertility after stripping-off Cs-contaminated top soil at Iitate village in Fukushima Prefecture

The agricultural fields were contaminated by the radionuclides ¹³⁴Cs and ¹³⁷Cs after the nuclear power plant accident in Fukushima. Prior to the accident, local farmers had successfully established sustainable agriculture in Iitate Village using natural farming practices and recycling. Since 2011, decontamination work such as stripping-off the top soil has been ongoing on agricultural land. Although decontamination is essential, it could cause an unfortunate decrease in soil fertility. Here, we examined the use of organic matter as a means to quickly recover the fertility of the agricultural top soil. We transplanted rice crops into three paddy plots: one received rice straw that had been harvested there last year, another received composted manure, and the third (control) received no additives after decontamination. We applied 40 kg/10a of basal fertilizer and 20 kg/10a of KCl each plot. The rates of Cs concentration in unhulled rice/rice straw were around 0.001. Tendency of plant heights increase and leaf chlorophyll content decrease were similar in the three treatment plots. However, the numbers of stems on 111 days after the transplant were 21, 15, and 19, unhulled rice yield were 513, 462, and 310 g/m², in the rice straw, cattle manure compost, and control plots, respectively. Soil properties of three plots were similar. Radioactive Cs concentrations in the new rice from each treatment plots were lower than the maximum allowed level set by the Japanese government. These results revealed that treating soil with rice straw might have great potential to aid the recovery of a paddy field after stripping-off the top soil. Notably, this treatment significantly improved the yield of rice and supplied organic matter without additional labor.     

Modifications of azoxymethane-induced carcinogenesis and 90-day oral toxicities of 2-tetradecylcyclobutanone as a radiolytic product of stearic acid in F344 rats

A 90-day oral toxicity test in rats was performed to evaluate the toxicity of 2-tetradecylcyclobutanone (2-tDCB), a unique radiolytic product of stearic acid. Six-week-old male and female F344 rats (n=15/group) were given 2-tDCB at concentrations of 0, 12, 60 and 300 ppm in a powder diet for 13 weeks. Slight dose-dependent increases in serum total protein and albumin in male rats were found, but these changes were not considered to be a toxic effect. The fasting, but not non-fasting, blood glucose levels of the male rats in the 300 ppm group and female rats in the 60 and 300 ppm groups were lower than those of the controls. Gas chromatography-mass spectrometry analysis showed dose-dependent accumulation of 2-tDCB in adipose tissue, notably in males. Next, we performed an azoxymethane (AOM)-induced two-stage carcinogenesis study. After injection of 6-week-old male F344 rats (n=30/group) once a week for 3 weeks, the animals received 2-tDCB at concentrations of 0, 10, 50 and 250 ppm in a powder diet for 25 weeks. The incidences of colon tumors for the 2-tDCB dosages were 34%, 45%, 40% and 37%, respectively, and were not statistically significant. These data suggest that 2-tDCB shows no toxic or tumor-modifying effects under the present conditions, and that the no-observed-adverse-effect level for 2-tDCB is 300 ppm in both sexes, equivalent to 15.5 mg/kg b.w./day in males and 16.5 mg/kg b.w./day in females.     

The smell and odorous components of dried shiitake mushroom, Lentinula edodes II: sensory evaluation by ordinary people

This study is part of an effort to improve the quality of dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler], in accordance with consumer preference, and deals with a preference survey using questionnaires combined with sensory evaluation. The smell was evaluated using powdered dried shiitake mushrooms. Age, original preference (OP), sex, sensory intensity (SI), hedonic preference (HP), and sample amount were set as parameters. About 70% of panelists liked dried shiitake mushrooms. There were significant correlations among age, OP, and SI. There was also a significant correlation between OP and HP, but no significant correlation between SI and HP. However, when the panelists were classified by OP, there was an optimal value between SI and HP for likers and neutralists. The calculated optimal concentration of dried shiitake mushrooms for likers and neutralists ranged widely. On the other hand, there was a significant negative correlation between SI and HP for dislikers, and their HP decreased according to the increase in the amount of the substance. The results showed that different concentrations of odorous components in dried shiitake mushrooms were needed to satisfy different consumer preferences.     

Immunohistochemical detection of cellular prion protein (PrPc) in the rat central nervous system

A simple conventional method of immunohistochemistry (i.e. fixing the frozen sections in cold methanol) was used to determine the immunolocalization of cellular prion protein (PrPc), with good results. In the rat cerebrum, the cytoplasm of neural cells in the cortex and corpus stratum, pia mater, membrane limitans gliae superficialis, choroid plexus and blood vessel wall were immunostained. The formation of network structures of immunostained neural and/or glial fibers in the cerebral cortex was also observed. These immunostained network structures of neural and/or glial fibers were also observed in cultured neural cells. The results suggest that fixation of frozen sections and cultured cells with cold methanol is a useful method for detecting the immunolocalization of PrPc and that PrPc exists in the various components of the central nervous system of the rat.     

Nutritional values and antioxidative activities of whole peanuts and peanut skins for ruminant feeds

This study was conducted to investigate the nutritive values of two peanut by‐products, nonstandardized whole peanuts and peanut skins, along with their effects on microbial growth and fermentation in the rumen, their roughage values, and their antioxidative activities by a digestion trial using four goats. The experimental rations were alfalfa haycube (basal ration), 85% alfalfa with 15% whole peanuts, and 70% alfalfa with 15% whole peanuts and 15% peanut skins. The ether extracts and crude protein in whole peanuts were 47% and 27% on a dry matter basis (DM) both with over 90% of digestibilities, resulting in total digestive nutrients (TDN) of 140%. Peanut skins also had a high energy value with 91% of TDN. Ruminal concentrations of total volatile fatty acids (VFA) and acetic acid decreased in the rations containing the peanut by‐products, but the NDF digestibility and ruminal microbial protein estimated from urinary purines was not altered by feeding the peanut by‐products. Plasma oxidative stress maker, malondialdehyde, tended to be lower when peanut skins were supplemented. Whole peanuts and peanut skins could be used as high‐energy and high‐protein diets for ruminants, and peanut skins would be expected as a feed having antioxidant functions.     

Spontaneous iron accumulation in hepatocytes of a 7-week-old female rat

Spontaneous iron accumulation in hepatocytes was observed in a 7-week-old female Han Wistar GALAS rat. Very fine yellowish brown pigments, which showed a positive reaction with Berlin Blue stain, were apparent in the cytoplasm close to the bile canaliculi, with a diminishing periportal-to-centrilobular gradient. There were also differences in distribution between and within lobes. Transmission electron microscopy revealed cytosolic ferritin and pericanalicular siderosomes in hepatocytes. No degeneration or necrotic changes were observed, and non-hepatocyte cells did not demonstrate any obvious accumulation of iron. There were no abnormalities in the animal other than this finding in the liver.     

Microbial conversion of bamboo hemicellulose hydrolysate to xylitol

A hemicellulose hydrolysate containing 19 g L^?1 xylose was prepared from the culm of bamboo (Phyllostachys pubescens) by hydrolysis with 3 % sulphuric acid with a liquor to solid ratio of 10 (g g^?1) at 121 °C for 1 h. After detoxification of the hydrolysate with a commercially available activated char followed by neutralisation with calcium carbonate, the resulting sugar solution was subjected to fermentation using the yeast, Candida magnoliae. The maximum xylitol production (10.5 g L^?1) and the maximum xylitol volumetric productivity (0.42 g L^?1 h^?1) were attained under agitation set at 400 min^?1 and aeration rate of 0.67 vvm (volume of air per volume of medium per minute). According to the results, a suitable control of the oxygen supply permits the xylitol formation from bamboo hemicellulose hydrolysate.     

The mechanism of bentazon selectivity

Absorption, translocation and metabolism of [¹⁴C]3-isopropyl-2,1,3-benzothiadiazin-4-one-2,2-dioxide (bentazon) by several plant species were investigated to determine the mechanism of bentazon selectivity.Marked selective phytotoxicities were observed between resistant rice (Oryza sativa L.) and susceptible Cyperus serotinus Rottb. when treated with bentazon. Absorption and transolcation of bentazon did not differ greatly between highly resistant rice and susceptible C. serotinus. However, a marked difference in bentazon metabolism occurred between the two species. In rice about 80% of the absorbed bentazon was metabolized within 24 h, and after 7 days about 85% was converted to a major water-soluble metabolite and unchanged bentazon was only 5%. In C. serotinus 50–75% of the radioactivity was unchanged bentazon after 7 days.Large amounts of water-soluble metabolites were detected in root-treated resistant plants such as barnyardgrass (Echinochloa crus-galli Beauv.), soybean (Glycine max Merr.) and corn (Zea mays L.), but only small amounts were present in such susceptible plants as Sagittaria pygmaea Miq. and Eleocharis kuroguwai Ohwi. Therefore, the mechanism of bentazon selectivity appears to be a difference between resistant and susceptible species in their ability to metabolize and detoxify bentazon.The major metabolite in rice was identified as 6-(3-isopropyl-2,1,3-benzothiadiazin-4-one-2,2-dioxide)-O-β-glucopyranoside, determined by GC-MS, NMR, IR and gas chromatography after hydrolysis with sulfuric acid or β-glucosidase.     

Taxonomic characterization of Pyricularia isolates from green foxtail and giant foxtail, wild foxtails in Japan

Twenty-eight Pyricularia isolates from two wild foxtails—green foxtail (Setaria viridis) and giant foxtail (S. faberii)—in Japan were taxonomically characterized by DNA analyses, mating tests, and pathogenicity assays. Although most of the isolates failed to produce perithecia in mating tests with Magnaporthe oryzae, a diagnostic polymerase chain reaction-restriction fragment length polymorphism phenotype of M. oryzae was detected in the beta-tubulin genomic region in all isolates. The pathogenicity assays revealed that host ranges of the isolates were similar to those of isolates from foxtail millet (S. italica), which were exclusively pathogenic on foxtail millet. In addition to the 28 isolates from wild foxtails, 22 Pyricularia isolates from 11 other grasses were analyzed by RFLP using single-copy sequences as probes. In a dendrogram constructed from the RFLP data, isolates that were previously identified as M. oryzae formed a single cluster. All the wild foxtail isolates formed a subcluster with foxtail millet isolates within the M. oryzae cluster. From these results, we conclude that Pyricularia isolates from the wild foxtails are closely related to isolates from foxtail millet and should be classified into the Setaria pathotype of M. oryzae.