Norsalsolinol uptake into secretory vesicles via vesicular monoamine transporter and its secretion by membrane depolarization or purinoceptor stimulation in PC12 cells.

The intracellular dynamics of norsalsolinol, a neurotoxin candidate causing parkinsonism-like symptoms, in PC12 cells was studied. We found that dopamine and norsalsolinol are co-localized to secretory granule layer by sucrose density gradient in norsalsolinol-treated PC12 cells. The norsalsolinol was actively taken up into isolated secretory vesicle fraction from PC12 cells with a Km value of 41.5+/-6.8 microM. The uptake of 10 microM of norsalsolinol was sensitive to reserpine (1 microM), an inhibitor of vesicular dopamine transporter, and dopamine, an endogenous substrate, but insensitive to GBR-12909, an inhibitor of dopamine transporter on plasma membrane. In norsalsolinol-treated PC12 cells, exposure to high K+ or ATP resulted in simultaneous release of norsalsolinol and dopamine. Time course of a release of dopamine and that of norsalsolinol evoked by 50 mM KCl or 100 microM ATP corresponded to each other. These releases were dependent on the concentrations of secretagogues. These data suggest that norsalsolinol is taken up with dopamine into secretory vesicle via vesicular catecholamine transporter.     

Influence of death struggle on the structural changes in chub mackerel muscle during chilled storage

ABSTRACT: Chub mackerel (34–35 cm, approximately 500 g), which were caught by fishing with a rod and line at the Bungo Channel, Oita prefecture, were rested overnight in a fish preserve and either killed by decapitation (control group) or allowed to struggle in air for 30 min (struggled group). Muscle samples were excised every 4 h, and measurements on breaking strength and histological observations were done for both groups. The breaking strength of muscle in the control group was significantly higher than that in the struggled group, whereby a decrease in breaking strength was delayed for 12 h compared to the struggled group. Light microscopy showed space extension among muscle cells in association with a decrease in breaking strength. Especially in the struggled group, the extended area was larger and the difference in area was significant at the time when breaking strength showed a significant difference. Using electron microscopy, the extended area showed cut and/or disappeared collagen fibrils. From these results, it was demonstrated that struggling to death promoted the degradation of collagen fibrils and the weakening of connective tissue and, resultantly, led to the faster softening of muscle of chub mackerel.     

A direct enzyme immunoassay for the measurement of furosemide in horse plasma

A new enzyme immunoassay (EIA) for the measurement of furosemide in horse plasma is described. The lower limit of detection of this EIA method was 7.8 ng/ml. The intra-and inter-assay coefficients of variation ranged from 2.5% to 4.9% and 7.5% to 9.8%, respectively. Cross-reactivity with other compounds was not observed. There was a high correlation (r2=0.987) between the high-performance liquid chromatography and EIA results obtained for furosemide concentrations in horse plasma. These results indicate that the newly developed EIA method is useful for the quantitative analysis of furosemide in horse plasma.     

Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission

The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator and supplies air bubbles to the rearing water. The growth of eel, which were fed a commercial diet, was satisfactory, with gross weight increases of up three times in 3 months. The survival rate under the congested experimental conditions was 91%. The foam separation unit maintained oxygen saturation in the rearing water at about 80%. Furthermore, fine colloidal substances were absorbed on the stable foam formed from eel mucus and were removed from the rearing water by foam separation. Ammonia oxidation and the removal of suspended solids were accomplished rapidly and simultaneously in the nitrification unit. The ammonia concentration and turbidity were kept at less than 1.2 mg of N per litre and 2.5 units, respectively. When the denitrification process was operated, nitrate that accumulated in the rearing water (151 mg of N per litre) was reduced to 40 mg of N per litre. The sludge was easily recovered from the nitrification and denitrification tanks, and the components were found suitable as compost. Based on these results, the intensive aquaculture of freshwater fish such as eel can be achieved using a closed recirculating system without emission.     

Studies on the properties of organic matfer in buried humic horizon derived from volcanic ash

To investigate the relationship between the change of humus property and time factor, the humus composition in the buried humic horizons with the age from 28,000 years B.P. to the present was studied, according to the method presented by Kumada et al. (7).

The fH decreased with the elapse of time and in case of most of humus in the buried humic horizons with the age over 10,000 years, the fH became lower than 40 and were in the form of so-called ‘combined’ humus.

When 3,000-4,000 years have passed since the surface soil buried, the humic acid first moved . to ‘combined form.’ Second, after over 10,000 years, the fulvic acid moved to ‘combined form.’

The humification of ‘free’ humic acid proceeded with the elapse of time till around 5,000 years but of 'combined' humic acid till around 7,000 years. Both the humification-degree of ‘free’ humic acid after around 5,000 years and of ‘combined’ humic acid after around 7,000 years decreased. The humification-degree of ‘free’ and ‘combined’ humic acid from the samples with the age about 15,000 years B.P. to 28,000 years B.P. may be the same.     

Effect of bensulfuron-methyl (a sulfonylurea herbicide) on the soil bacterial community of a paddy soil microcosm

The effect of bensulfuron-methyl (BSM) on a soil microbial community in a model paddy microcosm was studied. Total bacterial numbers in the overlying water and surface soil were monitored for 2 months after the application of BSM at the field rate and a ten-fold field rate. Pentachlorophenol (PCP) was used for comparison. Neither chemical affected the total bacterial numbers remarkably, either in the overlying water or in the surface soil. In contrast, the nitrification potential was significantly suppressed by the BSM application. The bacterial community structure, as evaluated by the denaturing gradient gel electrophoresis (DGGE) of PCR amplification products from bacterial 16S rDNA, was unaffected by the BSM treatments over 8 weeks in the surface soil, compared with the control (no pesticide). In contrast, the surface soil exposed to PCP at a ten-fold field rate showed different patterns from the controls at 4 weeks and 8 weeks after application. The DGGE patterns of the overlying water were much more variable than those of the surface soil in any treatments. Cluster analysis showed that the BSM plots were classified within the same group as the control at 1 week after application and that the BSM and PCP plots from 2 weeks onward after application were grouped differently from the control. Of 22 clones excised from the DGGE gels, 20 clones belonged to the Proteobacteria and two belonged to the Verrucomicrobia. It was considered that the impact of BSM on the overall microbial community (total numbers, community structure of soil) was negligible, although BSM had an impact on some specific functions of the soil microbial community (nitrification) and a part of the community (overlying water).     

An Improved Method for Isolating Violet Root Rot Fungus, Helicobasidium mompa, from Basidiocarps

Basidiocarps of the violet root rot fungus, Helicobasidium mompa, are less frequently used for isolation than are mycelial strands and sclerotia even though the basidiocarps are conspicuously produced at the trunk base of diseased plants. Basidiocarps are also more suitable for storage. This paper describes an improved method for obtaining pure cultures from basidiocarps using microcentrifuge tubes to facilitate the awkward steps of rinsing fungal materials under a dissecting microscope. Received 28 June 2000/ Accepted in revised form 4 August 2000