Identification of the dimethylbenzyl mercapturic acid in urine of rats treated with 1,2,3-trimethylbenzene.

The structure was investigated of the mercapturic acid excreted in urine of rats after the i.p. administration of 1,2,3-trimethylbenzene. Of the two regioisomeric mercapturic acids, i.e. N-acetyl-S-(2,3-dimethylbenzyl)-L-cysteine and N-acetyl-S-(2,6-dimethyl-benzyl)-L-cysteine, only the former was isolated by preparative HPLC and identified, by comparison with an authentic specimen. The excretion rate of the mercapturate was estimated to be approximately 5% of dose, not a substantial metabolic route.     

Onsets of schooling behavior and social transmission in chub mackerel Scomber japonicus

Grouping behavior has various types of antipredator functions. Some of these functions require social transmission of information, such as the many-eyes effect, whereas others do not, such as the dilution and confusion effects. Functions of grouping behavior would enhance with social transmission among group members. We investigated and compared the onsets of schooling behavior and social transmission of information in chub mackerel Scomber japonicus. Onset of schooling behavior was observed in rearing tanks by calculating the degree of parallel swimming. Onset of social transmission was examined by using visual cues from conspecifics. A group of five individuals was put in each of three experimental chambers from which they could see a group of conspecifics in the neighboring chamber. A weak electric stimulus was given to one of these chambers, and information transfer among individuals was observed. We found that social transmission by visual cues started on 30 days posthatching (25.1 mm in standard length), which was 2 weeks after the onset of schooling behavior. The late onset of social transmission relative to schooling behavior might be attributed to different predation pressure with development, or by underdevelopment of optic tectum, as the volume of the optic tectum did not increase just after the onset of schooling behavior.     

Identification of the dimethylbenzyl mercapturic acid in urine of rats administered with 1,2,4-trimethylbenzene

A study was undertaken of the mercapturic acid metabolism of 1,2,4-trimethylbenzene in the rat. Of three regioisomeric dimethylbenzyl mercapturic acids, i.e. 2,4-, 2,5- and 3,4-dimethylbenzyl isomers, the third isomer was not found in the urinary mercapturic acid isolated by preparative HPLC, from the comparison of NMR spectrum of the isolate with those of authentic specimens. The urinary mercapturate was then assigned to 2,4- and/or 2,5-dimethylbenzyl isomers. The excretion rate of the mercapturic acid was 14-20% of dose as 2,4-dimethylbenzyl isomer.     

Life history of the temperate subtidal gastropod Umbonium costatum

The life history and reproductive biology of the trochid sand snail Umbonium costatum (Kiener) were investigated on a subtidal sandy shore in Hakodate Bay, Japan between 1988 and 1991. Female U. costatum mature at 1 yr of age (shell diameter-11 mm), reproduce twice (in June-July and September-October) in successive years, grow to a maximum size (shell diameter=22 mm) at age 8 yr, increase annual fecundity with age from 2000 (age 1 yr) to 37000 (age 8 yr), and show a maximum monthly gonad somatic index of 8% which is constant among ages. In comparison to a previously studied life history of a tropical Umbonium vestiatium, temperate U. costatum shows more sustained growth and a longer life span after maturation. This could be explained by: (1) the optimal size model concerned with resource investment, in gametes (Sebens 1987); and by (2) bet hedging to compensate large variability in larval success at high latitudes. These two hypotheses are not mutually exclusive, but both are based on season-related extremes of environment at high latitudes where the period suitable for reproduction is short.     

A possible hybrid zone in the Mytilus edulis complex in Japan revealed by PCR markers

The adhesive protein allele of mussels collected at 13 points in Japan from Hokkaido to Kyushu was analyzed by the polymerase chain reaction using a set of primers which amplifies a part of the nonrepetitive region of the adhesive protein gene. While most mussels exhibited a 126 bp fragment, characteristic of the pure Mytilus galloprovincialis, 55 of 64 mussels sampled at Hiura and 1 of 14 mussels at Hakodate Port exhibited 168 and 126 bp fragments. Sequence analysis of the two fragments indicated that the 168 and 126 bp fragments are almost identical to previously reported sequences in M. trossulus and M. galloprovincialis, respectively. Since the frequency of heterozygous individuals in Hiura is very high, it is unlikely that they are simple hybrids. However, it is evident that mixing of genes occurred between the two species off Hokkaido. Received: 6 September 1996 / Accepted: 9 October 1996     

Development of a Practical Method to Detect Noroviruses Contamination in Composite Meals

Various methods to detect foodborne viruses including norovirus (NoV) in contaminated food have been developed. However, a practical method suitable for routine examination that can be applied for the detection of NoVs in oily, fatty, or emulsive food has not been established. In this study, we developed a new extraction and concentration method for detecting NoVs in contaminated composite meals. We spiked NoV-GI.4 or -GII.4 stool suspension into potato salad and stir-fried noodles. The food samples were suspended in homogenizing buffer and centrifuged to obtain a food emulsion. Then, anti-NoV-GI.4 or anti-NoV-GII.4 rabbit serum raised against recombinant virus-like particles or commercially available human gamma globulin and Staphylococcus aureus fixed with formalin as a source of protein A were added to the food emulsion. NoV-IgG-protein A-containing bacterial complexes were collected by centrifugation, and viral RNA was extracted. The detection limits of NoV RNA were 10–35 copies/g food for spiked NoVs in potato salad and stir-fried noodles. Human gamma globulin could also concentrate other NoV genotypes as well as other foodborne viruses, including sapovirus, hepatitis A virus, and adenovirus. This newly developed method can be used as to identify NoV contamination in composite foods and is also possibly applicable to other foodborne viruses.     

Some properties of trypsin-like proteases extracted from the seaweedCodium fragile and their purification

Two enzymes were purified from the green algaCodium fragile, collected in 1988 at Fukuoka, Japan, by batch-wise ion-exchange extraction, affinity chromatography and ion-exchange high-performance liquid chromatography (HPLC) using Boc-Ala-Ala-Pro-Arg-pNA as a substrate. The molecular weights of the enzymes were estimated as 38 000 and 39 000, using gel filtration HPLC. The enzymes had the same optimal pH range of 7 to 9 for both activities, and an exclusively hydrolyzed peptide bond on the carboxyl-terminal side of theL-arginine of peptidep-nitroanilides. The ratios of the enzymatic activity for X-Arg-pNA to X-Lys-pNA were larger than 100. The enzymes exhibited 30 times higher activity toward Boc-Ala-Ala-Pro-Arg-pNA when compared with trypsin. The activities were strongly inhibited by diisopropyl phosphofluoridate (DFP), and partially inhibited by phenylmethylsulfonyl fluoride (PMSF), benzamidine, leupeptin and antipain. The isolated enzymes were presumed to be trypsin-like serine protease from their primary substrate specificities and inactivation behavior.     

Trends in waste plastics and recycling

Zero emission is an ambitious project aimed at the conversion of the conventional top-down or one-directional flow type production systems of modern society to those of a recycling type. The basic idea underlying this project is to understand in detail the material flow mechanism in a particular segment of society and to evaluate the transformability of the hitherto one-directional types of process into recycling types. The authors, members of the Zero-Emission Research Group of Japan, are investigating the material flow of plastics in Japan. The present work describes the features of this project, as well as the results obtained so far. Received: May 28, 1998 / Accepted: October 16, 1998