4-(Methylthio)-3-butenyl isothiocyanate, a principal antimutagen in daikon (Raphanus sativus; Japanese white radish).

The antimutagenic activity of n-hexane extracts from eight strains of daikon (Raphanus sativus; Japanese white radish) have been examined using the UV-induced mutation assay of Escherichia coli B/r WP2. A correlation was found between the potency of antimutagenicity and the amount of 4-(methylthio)-3-butenyl isothiocyanate (MTBITC) in their n-hexane extracts. Because the pure MTBITC also showed antimutagenicity, MTBITC is presumably the active antimutagen principle in n-hexane extracts of daikon. Among the eight strains of daikon studied, Aokubi, the improved common strain in Japan, contained 71.0 micromol of MTBITC in 100 g of fresh daikon. In contrast, Karami and Momoyama, which are original wild strains, contained much more MTBITC (363.5 and 168.0 micromol/100 g, respectively). In addition, phenethyl isothiocyanate was found in a lesser amount (5-33 nmol/100 g) in eight strains of daikon, and allyl isothiocyanate and benzyl isothiocyanate were not detectable in any strains (<3 nmol/100 g). The amount of total isothiocyanate in grated daikon was 7.0 times higher than that in cut daikon measured after 30 min of cooking. Through eating habits, humans might be able to consume substantial amounts of the antimutagen MTBITC from dishes using the grated form of wild strains of daikon. Therefore, it is possible to substantially increase the intake of the antimutagenic ingredient of daikon (i.e., MTBITC) by changing food preferences and preparation procedures (i.e., using the grated form of the wild strains).     

Formation of a one-dimensional array of oxygen in a microporous metal-organic solid

We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O-O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).     

Isolation of an algal morphogenesis inducer from a marine bacterium

Ulva and Enteromorpha are cosmopolitan and familiar marine algal genera. It is well known that these green macroalgae lose their natural morphology during short-term cultivation under aseptic conditions and during long-term cultivation in nutrient-added seawater and adopt an unusual form instead. These phenomena led to the belief that undefined morphogenetic factors that were indispensable to the foliaceous morphology of macroalgae exist throughout the oceans. We characterize a causative factor, named thallusin, isolated from an epiphytic marine bacterium. Thallusin induces normal germination and morphogenesis of green macroalgae.     

Role of LBPA and Alix in multivesicular liposome formation and endosome organization

What are the components that control the assembly of subcellular organelles in eukaryotic cells? Although membranes can clearly be distorted by cytosolic factors, very little is known about the intrinsic mechanisms that control the biogenesis, shape, and organization of organellar membranes. Here, we found that the unconventional phospholipid lysobisphosphatidic acid (LBPA) could induce the formation of multivesicular liposomes that resembled the multivesicular endosomes that exist where this lipid is found in vivo. This process depended on the same pH gradient that exists across endosome membranes in vivo and was selectively controlled by Alix. In turn, Alix regulated the organization of LBPA-containing endosomes in vivo.     

Prevalence of Cryptosporidium parvum infection and pattern of oocyst shedding in calves in Japan

Cryptosporidium parvum infection and the pattern of oocyst shedding were observed in calves. A total of 480 fecal samples were collected from 30 calves (age, < or =30 days) over a period of 10 months from June 1998 to March 1999. A sucrose centrifugal flotation technique revealed 28/30 (93%) calves were passing Cryptosporidium oocysts. Oocyst shedding was first detected on the sixth day after birth, with 8% of the calves testing positive. This rate increased day by day and reached approximately 80% by day 15. Oocyst shedding varied from 1 to 13 days, with a mean of 7 days. Calves infected with C. parvum had a significantly higher rate of diarrhea (33%) than non-infected calves (8%) (P<0.05), suggesting C. parvum infection as the likely cause. The mean number of oocysts excreted by calves < or =30 days old was approximately 6x10(7) per gram of feces. These results indicated that one calf would excrete some 6x10(11) oocysts in the first month after birth, taking both the quantity of feces in a day and the period of excretion into consideration. Accordingly, it is clear that calves are important in the spread of cryptosporidiosis to calves and humans.     

Kinetic analysis of color changes in keyaki (Zelkova serrata) and sugi (Cryptomeria japonica) wood during heat treatment

The kinetics of color changes in keyaki (Zelkova serrata Makino) and sugi (Cryptomeria japonica D. Don) wood during heat treatment were examined. The color of wood specimens treated at 90, 120, 150, and 180 °C was measured by an imaging spectrophotometer and expressed using CIELAB color parameters. At any treatment temperature, values for L* and $ \Updelta E_{ab}^{*} $ decreased and increased in both wood species, respectively, with increased treatment time. Changes in a* and b* varied depending on wood species and treatment temperature. The color changes were successfully analyzed using the kinetic approach applying time–temperature superposition method. This approach elucidated and accurately predicted color changes during heat treatment.     

The discovery of pyridalyl: a novel insecticidal agent for controlling lepidopterous pests

Synthesis of analogues of two compounds with known insecticidal activity, both of which contain a 3,3-dichloro-2-propenyloxy group, produced 2-(trifluoromethyl)-4-phenoxyphenyl 3,3-dichloro-2-propenyl ether, which had weak activity against lepidopterous larvae. Structural modifications around this lead compound led to the development of pyridalyl [Pleo, S-1812; 2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-(trifluoromethyl)-2-pyridyloxy]propyl ether], which belongs to a new class of insecticides. Pyridalyl gives very good control of various lepidopterous and thysanopterous pests on cotton and vegetables, without phytotoxicity. It controls populations of Heliothis virescens F and Plutella xylostella (L) which are resistant to various currently used insecticides. It also produces unique insecticidal symptoms, so it may have a different mode of action from other existing insecticides. Pyridalyl is also less harmful than existing insecticides to various beneficial arthropods, so it should provide an important tool in IPM and insecticidal management programmes for the control of lepidopterous and thysanopterous pests. The first market introduction is expected in Japan and some Asian countries in the years between 2004 and 2005.     

Pharmacokinetics of zonisamide and drug interaction with phenobarbital in dogs

The purposes of the present study were to elucidate the pharmacokinetics of zonisamide, determine the presence of a drug interaction with phenobarbital, and evaluate how long any interaction lasted after discontinuation of phenobarbital in dogs. Five dogs received zonisamide (5 mg/kg, p.o. and i.v.) before and during repeated oral administration of phenobarbital (5 mg/kg, bid, for 30–35 days). Zonisamide (5 mg/kg, p.o.) was also administered 8, 10, and 12 weeks after discontinuation of phenobarbital. Blood was sampled until 24 h after each zonisamide administration and serum concentrations of zonisamide were determined. Repeated phenobarbital decreased the maximum serum concentration, area under the serum concentration vs. time curve, apparent elimination half-life, and bioavailability of zonisamide. Total clearance increased. Time to maximum serum concentration and volume distribution were not changed. The maximum serum concentration and area under the serum concentration vs. time curve of zonisamide continued to be low until 10 weeks after the discontinuation of phenobarbital. They were restored to the same serum concentration as before phenobarbital administration 12 weeks after the discontinuation of phenobarbital. These data suggested that repeated administration of a clinical dose of phenobarbital enhanced the clearance of zonisamide and the enhanced clearance lasted at least 10 weeks after the discontinuation of phenobarbital. Caution may be necessary when zonisamide is given with phenobarbital and when antiepileptic therapy is changed from phenobarbital to zonisamide.     

Difference in the stable nitrogen isotope ratio of Sargassum piluliferum (Phaeophyceae: Fucales) associated with fish and pearl oyster aquaculture facilities

In order to estimate the nitrogen loading from fish aquaculture facilities, we studied the nitrogen and carbon stable isotope ratios (δ¹⁵N and δ¹³C, respectively) in the brown macroalga Sargassum piluliferum and small amphipod crustaceans Caprella spp., both of which are lower trophic level biota found at fish and pearl oyster aquaculture facilities situated along the eastern coast of the Uwa Sea, Japan. This coastal region is one of the least populated areas along the Japanese coast. The mean concentrations of chlorophyll a, dissolved inorganic nitrogen, dissolved inorganic phosphate, and dissolved silicate-Si were 1.5- to 2-fold higher in samples from the fish aquaculture facilities than in those from the pearl oyster aquaculture facilities, indicating that the fish aquaculture facilities were associated with nitrogen loading. The δ¹⁵N abundance level in S. piluliferum collected from the fish aquaculture facilities was significantly higher (1.3‰) than that in macroalga collected at the pearl oyster aquaculture facilities, whereas that in Caprella spp., primary consumers, was only slightly higher (0.3‰). The feeding style of Caprella spp., which depends on suspended particulate organic matter and attached microalgae, is considered to the primary causal factor for the lack of a significant difference in δ¹⁵N abundance level between the two types of aquaculture facilities. Based on these results, we conclude that S. piluliferum found in close proximity of aquaculture facilities is a suitable organism for monitoring nitrogen loading from fish aquaculture facilities, through the analysis of δ¹⁵N.