Physical, chemical, and biological properties of s-allylcysteine, an amino acid derived from garlic.

Physical, chemical, and biological properties of S-allylcysteine (SAC) were investigated. SAC showed stable properties under tested conditions, and its acute/subacute toxicity was very minor in mice and rats (LD(50) value >54.7 mM/kg po; >20 mM/kg ip). The pharmacokinetics of SAC was investigated after oral administration of garlic supplement containing SAC to human volunteers. SAC from garlic consumption was rapidly absorbed from the gastrointestinal tract, however, the half-life and excretion time were more than 10 h and 30 h, respectively.     

Absorption of atmospheric NO2 by plants and soils

Tomato, sunflower and com plants were grown in culture solution containing three different concentrations of ¹⁵N-Iabelled KNO₃ (260 ppm N, 105 ppm N, and 26 ppm N) as a nitrogen nutrient, and fumigated with 0.3 ppm NO₂ for 2 weeks during their vegetative stages. The amount of NO₂ nitrogen absorbed into the plants was estimated by “difference method” and “¹⁵N method.” “¹⁵N method” was found to give more probable values than “difference method.” According to “¹⁵N method,” the nitrogen derived from NO₃ was about 16% (tomato), 22% (sunflower), and 14% (com) of the increased amount of total nitrogen in the whole plants in the 105 ppm N plot, and these percentages increased in the 26 ppm N plot. Difference in nitrogen concentration of the culture solution resulted in big change in the dryweight increase of the tomato and sunflower plants, but the absorption rate of NO₂ nitrogen based on the dry weight changed slightly. The absorption rate of NO₂ nitrogen was around 0.8 mg (gDW)^-1 day^-1 in tomato and sunflower plants, and 0.3 mg (gDW)^-1 day^-1 in com plant. Leaves were found to be an active sink of NO₂ and the nitrogen of NO₂ seemed to be rapidly transformed into compounds of high molecules in the leaf cells.     

Clay mineralogy and some chemical properties of Ap horizons of Ando soils used for paddy rice in Japan

The clay mineralogy of the Ap horizons of Ando soils in Japanese paddies was determined by a combination of methods and compared with that of Ando soils of uplands. Six of 13 paddy soil samples contained allophane and imogolite and none contained gibbsite, whereas parallel figures were 15 and 7 for 22 upland soil samples. Substantial numbers of diatoms were found in 5 paddy and 1 paddy-converted upland soil samples. The lack of gibbsite was related to the stage of soil formation rather than the paddy condition, whereas the presence of diatoms was related to both. Regarding layer silicates, there was no particular difference between the paddy and upland soil samples but one unidentified mineral with unique morphology and infrared spectrum was found in two paddy soil samples. There was no particular difference in phosphate adsorption between the paddy and upland soil samples.     

Flow regime shapes seasonal patterns of fish species richness and abundance in main and branch channels of a rice irrigation system

Current modernization of an irrigation system degrades fish habitats in quantity and quality and is a significant concern for biodiversity conservation and management of ecosystem services in rice farming landscapes. Irrigation systems consist of various types of channels, whose hydrological and hydraulic heterogeneities can contribute to the coexistence of diverse fish species in this flooded habitat. We compared seasonal patterns of fish species richness and abundance between main and branch channels which have different functions in an irrigation system with different flow temporality and magnitude: the main channels (mean width 425 cm and mean discharge 0.467 m³/s in irrigation period) and the branch channels (176 cm and 0.115 m³/s, respectively). The branch channels are small and temporary, but densities of fish species richness and abundance were not smaller than the main channels during the irrigation period. Further, clear positive hysteretic loops in species richness and abundance with discharge were found in the branch channels, which indicates that fish species richness and abundance gradually increased with discharge during this hydroperiod. Water velocity strongly constrained species richness and abundance in the main channels but not in the branch channels partially because of slow-flow patches at microhabitat scale with a larger vegetation coverage. We also found that the main channels provided deeper habitats in the non-irrigation period and contributed to maintain fish species richness and abundance. Therefore, managing both the main and branch channels as an indispensable, interconnected channel network can be a key for fish habitat conservation in an irrigation system.     

Automated acoustic method for counting and sizing farmed fish during transfer using DIDSON

Counting and sizing large farmed fish such as tuna is often performed during their transfer from one net cage to another. Dual-frequency identification sonar (DIDSON) provides an automated fish counting and sizing tool. However, its counter and sizer are not suitable for measuring farmed fish because of net movements due to currents and subsequent frequent image breakups. This paper presents a fully automated acoustic method to count and size farmed fish during fish transfer by using DIDSON imaging. The background is subtracted from the image after being stabilized by an image phase-only correlation method. The segmentation of the fish is obtained by tracing the edges with a contour tracing method. To prevent recounting the same fish, a Kalman filter algorithm was designed and adapted to predict fish movements. Automated counting was performed by analyzing the spatiotemporal trajectory of the track. The separated fish images were searched for and body length was obtained by summing down the centerline segments from the head to the tail of the fish. The proposed system was verified using farmed yellowtail, Seriola quinqueradiata (mean total length 83.1 cm) to obtain a sizing error of mean total length within 2.4 cm.     

Effects of Mn and Fe on growth of a coastal marine diatom <Emphasis Type="Italic">Talassiosira weissflogii</Emphasis> in the presence of precipitated Fe(III) hydroxide and EDTA-Fe(III) complex

The significance of Mn and Fe for the growth of the coastal marine diatom Thalassiosira weissflogii was investigated by culture experiments in the presence of precipitated Fe(III) hydroxide [am-Fe(III)] and EDTA-Fe(III) complex with or without Mn addition. The culture experiments in all media without any added Mn(II) resulted in the very low phytoplankton growth for cell density and chlorophyll a (Chl a) concentration. In contrast, sufficient Mn addition (25 nM) induced the maximum growth both for cell generation and Chl a production. By using an approach in which further iron uptake by T. weissflogii from external iron in the culture media is prevented by adding hydroxamate siderophore desferrioxamine B (DFB) during cultivation, we examined the ability of T. weissflogii to grow on intracellularly stored Fe after the DFB addition. The addition of DFB after 3- and 5-days of cultivation resulted in the lower growth rate and lower maximum yields for cell density and Chl a concentration in solid 7-day-aged am-Fe(III) medium than in freshly precipitated am-Fe(III) medium. The longer aging time of am-Fe(III) in medium reduced the supply of bioavailable iron in the medium by the slower dissolution rate of am-Fe(III) with the longer aging time. In addition, phytoplankton growth for cell generation in EDTA-Fe(III) complex media in the presence of insufficient Mn (0 and 5 nM) is strongly influenced by the bioavailable iron supply through the dissociation of EDTA-Fe(III). These results may suggest that T. weissflogii in longer aged am-Fe(III) medium and in EDTA-Fe(III) medium with a higher ratio of EDTA:Fe(III) is in Fe-limitation of growth, which probably increases the production rate of the reactive oxygen species (ROS), and the corresponding up-regulation of the superoxide dismuting enzyme Mn-SOD increases the requirement for Mn.     

Decreasing dietary lipids improves larval survival and growth of Japanese eel Anguilla japonica

Shark eggs-based diet is the only diet by which eel larvae can grow to glass eels in captivity. However, the high level of lipids in the diet is suggested to negatively affect eel larvae. This paper examines the effect of defatted shark eggs (DSE) and hen egg yolk (HY) on growth and survival of larvae of Japanese eel Anguilla japonica. Lyophilized shark egg and commercial HY were defatted with n-hexane, and four experimental diets were prepared using both defatted and untreated shark eggs and HY. Larvae were reared for 3 weeks by feeding the experimental diets. The highest survival rate was observed in the larvae fed DSE, and larvae fed HY showed the lowest survival rate. The best growth was found in larvae fed DSE, followed by shark eggs and defatted HY, and the worst growth was in HY-fed larvae. These results show that decreasing dietary lipids improves the nutritional value of both shark eggs and HY for eel larvae. Regulation of the dietary lipid level may positively affect the larval performance of eels by combination of ingredients with a low lipid content.     

Niche processes and conservation implications of fish community assembly in a rice irrigation system

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