Behavior of carbon dioxide in soils affected by tillage systems

Agricultural management plays an important role in the storage of carbon in soils. The behavior of soil CO₂ in an Andisol in two different tillage systems (no tillage and tillage) was studied. Soil-column incubation experiments were performed for a period of 150 days to conduct this study. Soil CO₂ flux, under no-tillage and tillage treatments, was observed to be 0.557 and 0.616 gCO₂-C m^?2 d^?1, respectively. The cumulative CO₂ flux under tillage treatment was observed to be higher than that under no-tillage treatment, but no distinct difference in the soil carbon stock was observed between both treatments. The soil CO₂ concentration under no-tillage treatment was clearly much higher than that under tillage treatment, except at a depth of 2.5 cm. Tillage decreased soil dry bulk density and enhanced soil air-filled porosity. Soil gas diffusivity, which depends on air-filled porosity, was increased by tillage at a depth of 0–15 cm, which contributed to their lower soil CO₂ concentration. CO₂ flux through the soil profile, calculated from the CO₂ concentration, decreased with depth. Compared to the deep soils, the surface soil (0–5 cm) showed greater variation in CO₂ flux. The CO₂ production at depths of 0–10 cm accounted for 62.2 and 51.7 % of the whole CO₂ production of the 0–30-cm soil profile for no-tillage and tillage treatments. CO₂ production was higher for soil under no tillage at depths of 0–10 cm, but contrary results were observed for soil at depths of 10–30 cm.     

N,N'-Bis(2-chloroethyl)-N-nitrosourea (BCNU)-induced Apoptosis of Neural Progenitor Cells in the Developing Fetal Rat Brain

N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU) is one of the major drugs used in chemotherapy against malignant gliomas due to its effects, such as induction of bifunctional alkylation of DNA and formation of interstrand DNA cross-linkages, and induces cortical malformations in the fetal and neonatal rat brain. In this study, pregnant rats were treated with 7.5 mg/kg of BCNU on gestational day 13 (GD 13), and their fetuses were collected from 12 to 72 hours after BCNU treatment in order to examine the timecourses of morphological and immunohistochemical changes in neural progenitor cells in the developing brain. The number of pyknotic cells in the telencephalon peaked at 24 h and then gradually decreased until 72 h. The majority of these pyknotic cells were positive for cleaved caspase-3, a key executioner of apoptosis. The pyknotic cells showed the ultrastructural characteristics of apoptosis. The number of p53-positive cells began to increase prior to the appearance of apoptotic cells and p21-positive cells. The number of phosphorylated-histone H3-positive cells (mitotic cells) decreased from 24 to 36 h. The number of Iba1-positive cells (microglial cells) in the telencephalon increased from 12 to 48 h. These results suggest that BCNU induces p53-dependent apoptosis and reduces proliferative activity, resulting in reduction of the weight of the telencephalon and the thickness of the telencephalic wall in the fetal brain. This study will help to clarify the mechanisms of BCNU-induced fetal brain toxicity.     

Impacts of pellet pH on nitrous oxide emission rates from cattle manure compost pellets

Previous reports indicated that the emission of nitrous oxide (N₂O) when manure compost pellets (MCP) were applied to soil was greater than when ordinary manure compost or inorganic fertilizer was applied, but that applying pellets of nitrogen-enriched manure compost, a by-product of deodorizing manure during composting, resulted in N₂O emission rates less than those from MCPs. To investigate the mechanism by which N₂O emission rates and cumulative emissions were reduced in nitrogen-enriched manure composts pellets (N+MCP), we studied the impact of pellet pH on N₂O emission, because pH is different between MCP (pH 8.6) and N+MCP (pH 5.3). In an incubation experiment, the pH of pellets was adjusted to five levels (5.3, 6.0, 7.0, 8.0 and 8.6) with acid or alkaline solutions, and the pellets were incubated without soil in a beaker at 30°C for 90 d (MCP) or 42 d (N+MCP). A large peak in N₂O emission rate was observed soon after beginning the incubation (within 1–3 d) in the neutral and alkaline treatments for both MCP and N+MCP, and these peaks corresponded to a rise in the pellet nitrite contents. Thus, this N₂O emission peak might have been generated by the denitrification of nitrite in the pellets. In the acid treatments of MCP, the N₂O emission was distributed more in the later incubation period (14–90 d), when the reduction of nitrate in MCP occurred. This led to a significant increase in cumulative N₂O emission as compared with the alkaline treatments for MCP. Regarding the mechanism by which N₂O emission was reduced in N+MCP, although larger cumulative N₂O emission rates in the earlier stage (0–14 d for MCP and 0–7 d for N+MCP) were observed when the pellet pH was adjusted close to 7.0, lowering the pH of MCP to 5.3 (the pH of N+MCP) did not demonstrate a significant decrease in cumulative N₂O emission as compared with the original pH treatment (pH 8.6). These results indicate that pellet pH might not relate directly to the mechanism by which N₂O emission was reduced in N+MCP.     

Lithological effects in soil formation and soil slips on weathering-limited slopes underlain by granitic bedrocks in Japan

Soil slips occur every few years due to heavy rains on biotite granite (Gb) and hornblende biotite granite (Ghb) slopes in the Taga Mountains, Ibaraki Prefecture, Japan. The occurrence density of soil slips per unit area is 2.7 times greater in the Gb slopes than that in Ghb slopes. We examined the chemical, mineral, physical, and mechanical properties of two soil profiles on soil-slip scars in these slopes to study the effect of bedrock mineral composition on the density of soil slips. For a given size of mineral grain, the amount of biotite (which is susceptible to chemical weathering) in granitic bedrocks strongly influenced the density of soil slips. In the Gb slope the soil layer becomes thinner because of the smaller proportion of biotite in the bedrock; this restricts the downward movement of soil water into the material below the slip plane. During heavy rainfall the water surface then rises toward the slope surface above the slip plane. This promotes soil slips, increasing the density of soil-slip scars. In contrast, in the Ghb slope, with more biotite in the bedrock, the soil layer becomes thicker, so that soil water moves easily into the material beneath the slip plane. This limits the rise of water surface toward the slope surface above the slip plane even during heavy rainfalls. There are consequently fewer soil slips and density of soil-slip scars.     

Leptospirosis with multiple organ dysfunction in a mongoose-scat-detection dog infected with Leptospira interrogans serogroup Hebdomadis,Okinawa, Japan

A 2-year-old male mongoose-scat-detection dog was diagnosed with leptospirosis by urine PCR. The patient developed acute renal failure, hepatic dysfunction, and disseminated intravascular coagulation. Treatment with antibiotics was administered, including ampicillin and doxycycline, and supportive care management was provided. Seroconversion against serogroup Hebdomadis was observed on day 8. The leptospiral gene flaB was detected only in urine collected on day 1, from which Leptospira interrogans ST329 was identified by multilocus sequence typing using seven housekeeping genes. L. interrogans serogroup Hebdomadis ST329 has been isolated from mongooses and humans in Okinawa, Japan. This patient received early treatment with antibiotics, which may have contributed to the early recovery of renal function and removal of L. interrogans from kidney tissue.     

Optimization of the supplemental essential amino acids to a fish meal-free diet based on fermented soybean meal for rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>

To minimize the supplemental essential amino acids (EAAs) to a fish meal-free diet for rainbow trout Oncorhynchus mykiss, four types of fish meal-free diets and a control fish meal-based diet were fed to triplicate groups of trout (initial BW, 16 g) for 10 weeks. Two fish meal-free diets based on a fermented and an unfermented soybean meal were unsupplemented with EAAs (diet FSBM and SBM), and two fish meal-free diets based on the fermented soybean meal were supplemented with a combination of lysine and methionine (diet F + ML) and all EAAs (diet F + All), the EAA contents of which were lower than those of the control diet (diet FM). Although physiological conditions such as the biliary bile acid status and morphological features of fish fed diet FSBM were improved and similar to those of fish fed diet FM, the growth performance was not significantly different (P > 0.05) from fish fed diet SBM. The growth performances and whole body protein contents of fish fed F + ML and F + All diets were similarly improved compared to fish fed diet FSBM. These findings indicate that supplementation of lysine and methionine to a fermented soybean meal-based fish meal-free diet is enough to maximize the amino acid utilization of the diet.     

Dynamics of invasion and dissemination of H5N6 highly pathogenic avian influenza viruses in 2016–2017 winter in Japan

Large highly pathogenic avian influenza (HPAI) outbreaks caused by clade 2.3.4.4e H5N6 viruses occurred in Japan during the 2016–2017 winter. To date, several reports regarding these outbreaks have been published, however a comprehensive study including geographical and time course validations has not been performed. Herein, 58 Japanese HPAI virus (HPAIV) isolates from the 2016–2017 season were added for phylogenetic analyses and the antigenic relationships among the causal viruses were elucidated. The locations where HPAIVs were found in the early phase of the outbreaks were clustered into three regions. Genotypes C1, C5, and C6–8 HPAIVs were found in specific areas. Two strains had phylogenetically distinct hemagglutinin (HA) and non-structural (NS) genes from other previously identified strains, respectively. The estimated latest divergence date between the viral genotypes suggests that genetic reassortment occurred in bird populations before their winter migration to Japan. Antigenic differences in 2016–2017 HPAIVs were not observed, suggesting that antibody pressure in the birds did not contribute to the selection of HPAIV genotypes. In the late phase, the majority of HPAI cases in wild birds occurred south of the lake freezing line. At the end of the outbreak, HPAI re-occurred in East coast region, which may be due to the spring migration route of Anas bird species. These trends were similar to those observed in the 2010–2011 outbreaks, suggesting there is a typical pattern of seeding and dissemination of HPAIV in Japan.     

Effect of microwave decomposition on inductively coupled plasma spectrometry analysis of minerals in oysters

Fisheries Science - Oysters, which can be cultivated in oceans, are rich in nutrients. Recently, our group has reported the rapid analysis of multiple minerals in Crassostrea gigas oysters by...     

Production of transparent exopolymer particles by four diatom species

The production of transparent exopolymer particles (TEP) by four diatoms, Coscinodiscus granii, Eucampia zodiacus, Rhizosolenia setigera, and Skeletonema sp., was examined. Most of the TEP in C. granii (74% of the maximum) were produced during the growth phase. In contrast, most of the TEP in E. zodiacus (73%), R. setigera (74%), and Skeletonema sp. (70%) were produced during the stationary and declining phases. The C. granii TEP production rate was highest in the growth phase, whereas those in E. zodiacus, R. setigera, and Skeletonema sp. were highest in the stationary–decline phase. The TEP concentrations per cell and the cell volume of C. granii were 34.97 ± 4.114 (mean ± SD) ng Xeq./cell (xanthan gum equivalents per cell) and 341.6 ± 56.33 fg Xeq./μm³, and were 23.01 and 4.32 times higher than the values obtained from the other three diatoms, respectively. The results suggest that the mechanisms of TEP production differ with growth stage and diatom species. Therefore, it is likely that the differences in TEP production among the diatom species influence the complexity of TEP dynamics in aquatic environments.     

Effect of an alcohol extract from a defatted soybean meal supplemented with a casein-based semi-purified diet on the biliary bile status and intestinal conditions in rainbow trout Oncorhynchus mykiss (Walbaum)

A feeding experiment was conducted to examine the effect of a supplemental ethanol extract from a defatted soybean meal on the biliary bile status and intestinal conditions of rainbow trout Oncorhynchus mykiss . A semi-purified control diet based on casein (Cont) and three diets supplemented with the extract (ES), bovine bile salts (BS) and their combination (ESBS) were fed to trout (10 g) for 6 weeks. The growth, feed efficiency ratio, fat digestibility and gallbladder- and hepato-somatic indices of fish fed diet ES decreased. Compared with this group, these parameters were improved in fish fed diet ESBS. The total biliary bile salt content was the lowest in fish fed diet ES and this group had a high proportion of chenodeoxycholyltaurine. The inclusion of the bile salts to diet ES (diet ESBS) increased the total biliary bile salt content. A similar trend was observed in the bile salt concentration of intestinal digesta. Although morphological changes occurred in epithelial cells of the distal intestine of fish fed diet ES, the histological features of fish fed diet ESBS were similar to those of fish fed diet Cont. These results indicate that alcohol-soluble substances of soybean meal cause physiological changes in the biliary bile and intestine of rainbow trout.