Comparison of the glucosinolate-myrosinase systems among daikon (Raphanus sativus, Japanese white radish) varieties

Myrosinase is a cytosolic plant enzyme present in daikon ( Raphanus sativus, Japanese white radish) roots that hydrolyzes 4-methylthio-3-butenyl glucosinolate (MTBGLS) into the natural pungent agent 4-methylthio-3-butenyl isothiocyanate (MTBITC), which possesses antimicrobial, antimutagenic, and anticarcinogenic properties. The concentration of MTBGLS, myrosinase activity, and production of MTBITC in seven daikon varieties (one conventional and six heirlooms) were determined to rank the activity of the glucosinolate-myrosinase system and identify critical factors influencing the production of MTBITC. The six heirloom varieties produced 2.0-11.5 times higher levels of MTBITC as compared to the conventional variety, Aokubi, which is consumed by the present Japanese population. The myrosinase was located exclusively in the outer epidermal layer in Aokubi, and MTBGLS was widely distributed throughout the root tissue. Although the skin is a potentially rich source of myrosinase in Aokubi, the skin is usually peeled off in the current practice of preparing daikon for cooking. New practices are therefore proposed for the preparation of daikon tubers that eliminate the peeling of the skin to avoid removing the enzyme needed to convert MTBGLS to the health-beneficial MTBITC. It is also concluded that the consumption of heirloom daikon varieties in addition to changes in food preparation will optimize the health benefits of daikon.     

Effect of fish in rice-fish culture on the rice yield

Rice-fish culture, which means the simultaneous culture of rice and fish, is one of the best options to increase food production from limited land and is practiced in many countries in the world. Although many researchers and farmers believe that the rice yield is increased by fish farming in paddy fields, this hypothesis has never been fully tested. Here, we report ecological processes leading to higher rice yields in the rice-fish culture using crucian carp (Carassius complex), which have adapted to the paddy field ecosystem in Japan. We compare the rice-fish and rice-only plots in the experimental paddy field for biota, water quality, and rice yield. Coverage of duckweed and densities of zooplankton and benthic invertebrates in the rice-fish plots were lower than those in the rice-only plots, indicating that fish utilized them as food. NO₃–N concentration in the rice-fish plots was higher than that in the rice-only plots, indicating that the increase in NO₃–N concentration results from excretion of unutilized food nutrients by the fish. Consequently, rice yield in the rice-fish plots was 20% higher than that in the rice-only plots. The fertilizing effect of the fish excrement probably increased rice yield.     

Stress hormone responses in ayu Plecoglossus altivelis in reaction to different catching methods: comparisons between electrofishing and cast netting

It is important to select the most appropriate method for fish sampling in streams and rivers; the sampling efficiency as well as any negative effect of the method of fish sampling on fishes such as stress, injury, and mortality must be considered. This study aimed to investigate stress hormone responses in ayu Plecoglossus altivelis in reaction to direct current (DC) electrofishing, alternating current (AC) electrofishing, and cast netting in artificial streams. The mortality, injury rate, and catch efficiency of these catching methods were also compared. It was found that immediately after capture, fish caught using a cast net exhibited significantly higher cortisol levels than did control fish that were caught rapidly by a hand net. Cortisol levels did not differ between electroshocked fish and the controls. Time required to catch 12 fish was shorter when DC was used (20 s) than when AC was used (45 s). The time required to catch fish greatly increased when a cast net was used (840 s). Cortisol levels in DC electroshocked and control treatment groups were at resting levels 24 and 48 h after capture. However, higher cortisol levels were found in fish captured using a cast net at both these time points. Cortisol levels in AC electroshocked fish returned to lower levels at 24 h, but increased again at 48 h. Furthermore, 48 h following capture, the fish caught by AC electrofishing exhibited higher mortality (7.5 %) than those captured by other methods (0 %). Spinal injury was also detected in one of the fish in this group. Considering these findings, DC electrofishing is the most effective and least damaging method for collecting P. altivelis in streams with respect to stress, physical damage, and efficiency.     

Cesium-137 discharge into the freshwater fishery ground of grazing fish, ayu Plecoglossus altivelis after the March 2011 Fukushima nuclear accident

The Fukushima nuclear accident led to deposition of radionuclides into the freshwater fishery ground of ayu Plecoglossus altivelis. For the purpose of more comprehensive understanding of the radioactive contamination, cesium-137 (¹³⁷Cs) was analyzed in running water, muddy sediment, attached algae, and ayu using samples from three river systems with different levels of contamination within Fukushima Prefecture in summer and autumn 2011. The amount of ¹³⁷Cs contained in water as well as in sediment declined over an interval of two months, although the concentration in sediment samples was up to 10,000-fold higher than that in water samples. The changes in ¹³⁷Cs concentration of algae showed different courses among the three river systems, the concentration being greater in autumn in the river systems with high and moderate radioactive contamination. ¹³⁷Cs detected within a single stock of ayu appeared to be excreted rather rapidly with a calculated half-life of approximately 39 days, while the concentration ratio ranged from 10³ to 10⁴ l/kg, attaining higher levels than previously reported. These findings indicate that the most important pathway of ¹³⁷Cs into ayu is via intake of algae as food but that the retention time of ¹³⁷Cs inside ayu is relatively short.     

Effect of co‐culture with intact embryos on development of bovine separated blastomeres

To improve embryo development in bovine separated blastomeres, we evaluated applicability of co‐culture with intact embryos. The morphological quality of blastocysts derived from separated blastomeres and rate of blastocyst formation were only slightly increased when the cells were co‐cultured with intact embryos, which did not provide significant differences when statistically analyzed. However, the cell count of inner cell mass (ICM), trophectoderm (TE) and total number of cells in Day 8 blastocysts were significantly higher when the cells were co‐cultured with the intact embryos than those with the cells cultured individually (P < 0.05). Transfer of four monozygotic pairs of blastocysts derived from the cells co‐cultured with intact embryos led to three pregnancies even when the blastomeres were produced by in vitro maturation and in vitro fertilization of oocytes collected by ovum pick‐up from elite cows. These results suggest that co‐culturing with intact embryos may enhance development of bovine separated blastomere.     

Itokawa dust particles: a direct link between S-type asteroids and ordinary chondrites

The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.     

Vascular distribution in ruptured canine cranial cruciate ligament

Objective: To (1) determine the microanatomic vascular distribution in ruptured canine cranial cruciate ligaments (CCL) using specific vascular immunohistochemical techniques, and (2) compare vessel density between ruptured and intact canine CCL and between different areas of interest in ruptured CCL using histomorphometric analysis. Study Design: In vitro study. Animals: Dogs (n=41) admitted for surgical treatment of ruptured CCL and 19 dogs euthanatized for nonorthopedic conditions. Methods: Diseased (variable CCL rupture) and intact (normal control) CCL were processed for immunohistochemical staining specific to vessels (factor VIII, laminin). Mean vascular density was assessed and compared in areas of interest (torn end versus remaining core regions of CCL, proximal femoral versus distal tibial core CCL regions). Results: Ruptured CCL was more vascular than intact CCL; however there was no difference in vascular density between the torn end and the remaining core area of the ruptured CCL. Ruptured CCL was vascularized to a greater degree at the proximal portion than the distal portion of the CCL. Partially ruptured CCLs had a higher vessel density than completely ruptured CCLs. Conclusions: Vascular density is increased in diseased CCL compared with intact CCL. It remains to be determined whether this finding is associated with the cause of CCL rupture or is a result of CCL degeneration and rupture.     

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.     

Phase transition of FeO and stratification in Earth's outer core

Light elements such as oxygen in Earth's core influence the physical properties of the iron alloys that exist in this region. Describing the high-pressure behavior of these materials at core conditions constrains models of core structure and dynamics. From x-ray diffraction measurements of iron monoxide (FeO) at high pressure and temperature, we show that sodium chloride (NaCl)-type (B1) FeO transforms to a cesium chloride (CsCl)-type (B2) phase above 240 gigapascals at 4000 kelvin with 2% density increase. The oxygen-bearing liquid in the middle of the outer core therefore has a modified Fe-O bonding environment that, according to our numerical simulations, suppresses convection. The phase-induced stratification is seismologically invisible but strongly affects the geodynamo.