Masami Nishina

Inhibition of flight in Periplaneta americana (Linn.) by a trehalase inhibitor, validoxylamine A

Abstract Male adults of Periplaneta americana were graded into three groups according to their flight activity; very active (continuous flight longer than 5 min), active (1–5 min) and inactive (shorter than 1 min). 1H-NMR analysis showed that approx. 30 mM trehalose was present in the haemolymph of each of the above categories of untreated cockroaches. After exhaustive flight, the haemolymph trehalose concentration in very active individuals decreased to 2.5 min. The trehalase activity of the flight muscle was inhibited about 70% and the haemolymph trehalose concentration increased to about 3 times the normal level without change in the other haemolymph components. Trehalose also accumulated in the tissues of the cockroaches injected with validoxylamine A. These observations suggest that validoxylamine A inhibits the muscle trehalase and prevents the use of trehalose as a source of energy for flight.

Assessment of the toxicity of linear alkylbenzene sulfonate and quaternary alkylammonium chloride by measuring 13C-glycerol in Dunaliella sp.

Abstract The toxic effects of linear alkylbenzenesulfonate (LAS) and quaternary alkylammonium chloride on Dunaliella sp. were studied by measuring 13 C-glycerol. 13 C-glycerol (five isomers of [1,2,1′- 13 C 1,2,3 ]-glycerol) was produced in Dunaliella sp. from 13 C-sodium bicarbonate added and the amounts of 13 C-glycerol was lowered quantitatively with increased concentration of surfactants. The ratio of glycerol to 13 C-glycerol was found to be about 45 : 55 by gas chromatographic/mass spectrometric analysis. The 24-h median effective concentration (EC50-24h) were 3.5 mg/l for LAS, 0.79 mg/1 for alkyltrimethyl-ammonium chloride (TM), 18 mg/l for dialkyldimethylammonium chloride (DM) and 1.3 mg/l for alkyldimethylbenzylammonium chloride (BM) : the toxic potencies were in the order of TM>BM>LAS>DM. The suppression of 13 C-glycerol formation by LAS seemed to be related to the process of photosynthesis from 13 C-sodium bicarbonate.

Characteristics of cesium accumulation in the filamentous soil bacterium Streptomyces sp. K202

A filamentous soil bacterium, strain K202, was isolated from soil where an edible mushroom (Boletopsis leucomelas) was growing and identified as belonging to the genus Streptomyces on the basis of its morphological characteristics and the presence of LL-2, 6-diaminopimelic acid. We studied the existence states of Cs and its migration from extracellular to intracellular fluid in the mycelia of Streptomyces sp. K202. The results indicated that Cs accumulated in the cells through at least 2 steps: in the first step, Cs(+) was immediately and non-specifically adsorbed on the negatively charged cell surface, and in the second step, this adsorbed Cs(+) was taken up into the cytoplasm, and a part of the Cs entering the cytoplasm was taken up by an energy-dependent transport system(s). Further, we confirmed that a part of the Cs(+) was taken up into the mycelia competitively with K(+), because K(+) uptake into the intact mycelia of the strain was significantly inhibited by the presence of Cs(+) in the culture media. This suggested that part of the Cs is transported by the potassium transport system. Moreover, (133)Cs-NMR spectra and SEM-EDX spectra of the mycelia that accumulated Cs showed the presence of at least 2 intracellular Cs states: Cs(+) trapped by intercellular materials such as polyphosphate and Cs(+) present in a cytoplasmic pool.

Decrease in cerebral free magnesium concentration following closed head injury and effects of VA-045 in rats

1. We examined the alterations in cerebral free Mg2+ concentration in closed head injury (CHI) in rats and the effects of VA-045, a novel apovincaminic acid derivative, on them with in vivo 31P-NMR. 2. Free Mg2+ decreased by about 30% within 20 min after head impact and, afterward, it gradually decreased further to reach about 60% of the control level after 3 hr. VA-045 inhibited the decrease. 3. In nonimpacted rats, VA-045 did not alter the free Mg2+ level. 4. The decrease in cerebral free Mg2+ following CHI may be a critical factor in the development of irreversible tissue injury, and VA-045 may prevent it.

Increased cerebral choline-compounds in Duchenne muscular dystrophy.

WE investigated the hypothesis that cell membrane function is abnormal in brains of subjects with Duchenne muscular dystrophy (DMD) using proton-nuclear magnetic resonance (NMR) spectroscopy of human brain extracts. The total amount of choline-containing compounds was significantly higher (about three times) than in normal controls and patients with other myopathies, while N-acetyl-L-aspartic acid and creatine were within the normal range. These findings indicate that abnormal cell membrane function may be correlated with the abnormal dystrophin or lack of dystrophin in the brain of patients with DMD.

Studies on uptake of cesium by mycelium of the mushroom ( Pleurotus ostreatus ) by133Cs-NMR

Sufficient information on the mechanisms of radiocesium translation from substrate to mushroom and long-term radiocesium accumulation is still not available, though high concentrations of radiocesium were reported in the fruiting bodies of various species of mushrooms especially after the Chernobyl accident. We studied the concentration and existing state of Cs in the cultured mycelium of the edible mushroom (Pleurotus ostreatus (Fr.) Kummer Y-1) using NMR. The133Cs NMR resulting spectra exhibited two resonance signals arising from the mycelium whereas one resonance signal from the external medium and CsCl standard solution. The chemical form of the signal in the downfield found in the only mycelium might be concerned with Cs accumulation in the mycelium.

1H- and 13C-NMR spectroscopic study of the metabolites in young adult Angiostrongylus cantonensis maintained in vitro

1H- and 13C-nuclear magnetic resonance (NMR) spectroscopy were used to study metabolites excreted by young adult Angiostrongylus cantonensis maintained aerobically in the presence of D-[13C6]glucose. End-products of glucose metabolism identified and quantitated by means of 1H-NMR were lactate, acetate and alanine, in the molar ratio of 1:0.13:0.05 for males and 1:0.07:0.04 for females. 13C-NMR analyses proved that all the three products originated from the glucose present in the medium.

Benzodiazepine-sensitive GABAA receptors in the commissural subnucleus of the NTS are involved in the carotid chemoreceptor reflex in rats

We studied the role of benzodiazepine (BDZ) receptors in the commissural subnucleus of the nucleus tractus solitarius (commNTS) in chemoreceptor reflex in urethane-anesthetized, pancronium-immobilized, artificially ventilated and bilaterally vagotomized rats. A BDZ agonist, diazepam (1-4 micromol/kg), administered intravenously reduced resting phrenic nerve activity (PNA) and blood pressure (BP). Stimulation of carotid chemoreceptors induced an increase in PNA and an increase in BP. Diazepam inhibited this chemoreceptor reflex. The effects of intravenous injection of diazepam (4 micromol/kg) on the chemoreceptor reflex were antagonized by microinjection of the BDZ antagonist flumazenil (100 pmol) into the commNTS. Microinjection of flumazenil (100 pmol) alone had no effect on the basal PNA and BP, and the chemoreceptor reflex. These results suggest that BDZ receptors are present in the carotid chemoreceptor reflex pathway in the commNTS and potentiate GABA(A) transmission.

13C and 31P NMR spectroscopic studies on glucose metabolism in Tribolium confusum

Nuclear magnetic resonance (NMR) technology was applied to study the glucose metabolism in Tribolium confusum (Coleoptera). 13C signals of D‐(1‐13C)glucose eaten by beetles were clearly detected in such metabolites of the glucose metabolism as glycogen, trehalose, triacylglycerol, alanine and proline by 13C‐NMR. After glucose feeding the 31P‐NMR spectra of T. confusum showed the signal intensity increases in arginine‐phosphate, sugar‐phosphate and uridine diphosphoglucose. The results demonstrated the potential of NMR analysis for the study of glucose metabolism in T. confusum.