Negative relationship between odor-induced spike activity and spontaneous oscillations in the primary olfactory system of the terrestrial slug Limax marginatus

Although primary olfactory systems in various animals display spontaneous oscillatory activity, its functional significance in olfactory processing has not been elucidated. The tentacular ganglion, the primary olfactory system of the terrestrial slug Limax marginatus, also displays spontaneous oscillatory activity at 1-2 Hz. In the present study, we examined the relationship between odor-evoked spike activity and spontaneous field potential oscillations in the tentacular nerve, representing the pathway from the primary olfactory system to the olfactory center. Neural activity was recorded from the tentacular nerve before, during and after application of various odors (garlic, carrot, and rat chow) to the sensory epithelium and the changes in firing rate and spontaneous oscillations were analyzed. We detected the baseline amplitude of the oscillations and baseline spike activity before stimulation. Odor stimulations for 20 s or 60 s evoked a transient increase in the firing rate followed by a decrease in the amplitude of spontaneous oscillations. The decrease in the amplitude was larger in the first 8 s of stimulation and subsequently showed recovery during stimulation. The amplitude of the recovered oscillations often fluctuated. Odor-evoked spikes appeared when the amplitude of the recovered oscillations was transiently small. These results suggest that the large oscillations could inhibit spike activity whereas the first transient increase in spike activity was followed by the decrease in the oscillation amplitude. Our results indicate that there is a significant negative correlation between spontaneous oscillations and odor-evoked spike activity, suggesting that the spontaneous oscillations contribute to the olfactory processing in slugs.     

Quinapril inhibits progression of heart failure and fibrosis in rats with dilated cardiomyopathy after myocarditis

The cardioprotective properties of quinapril, an angiotensin-converting enzyme inhibitor, were studied in a rat model of dilated cardiomyopathy. Twenty-eight days after immunization of pig cardiac myosin, four groups rats were given 0.2 mg/kg (Q0.2, n = 11), 2 mg/kg (Q2, n = 11) or 20 mg/kg (Q20, n = 11) of quinapril or vehicle (V, n = 15) orally once a day. After 1 month, left ventricular end-diastolic pressure (LVEDP), ±dP/dt, area of myocardial fibrosis, and myocardial mRNA expression of transforming growth factor (TGF)-1, collagen-III and fibronectin were measured. Four of 15 (27%) rats in V and two of 11 (18%) in Q0.2 died. None of the animals in Q2 or Q20 died. The LVEDP was higher and ±dP/dt was lower in V (14.1 ± 2.0 mmHg and +2409 ± 150/–2318 ± 235 mmHg/sec) than in age-matched normal rats (5.0 ± 0.6 mmHg and +6173 ± 191/–7120 ± 74 mmHg/sec; all p < 0.01). After quinapril treatment, LVEDP was decreased and ±dP/dt was increased in a dose-dependent manner (10.8 ± 1.8 mmHg and +3211 ± 307/–2928 ± 390 mmHg/sec in Q0.2, 9.4 ± 1.5 mmHg and +2871 ± 270/–2966 ± 366 mmHg/sec in Q2, and 6.6 ± 1.5 mmHg, and +3569 ± 169/–3960 ± 203 mmHg/sec in Q20). Increased expression levels of TGF-1, collagen-III and fibronectin mRNA in V were reduced in Q20. Quinapril improved survival rate and cardiac function in rats with dilated cardiomyopathy after myocarditis. Furthermore, myocardial fibrosis was regressed and myocardial structure returned to nearly normal in animals treated with quinapril.     

Diurnal and circadian rhythm in compound eye of cricket (Gryllus bimaculatus): changes in structure and photon capture efficiency

Day-night changes in rhabdom size of compound eyes were investigated in three groups of crickets (Gryllus bimaculatus): nymphs and adult males and females. In both adults and nymphs, the rhabdoms were larger at night than during a day. In adults, the mean rhabdom occupation ratios (RORs) of ommatidial retinulae at midnight were about two times greater than the values at midday. This change contributes to control of the photon capture efficiency (PCE) of the eye according to photic environment. The RORs of adult males at midnight were higher than those of both adult females and nymphs. This suggests that the PCE of the compound eye of adult males is the greatest of all groups. Under constant darkness, day-night changes in ROR were detected only in adult males, but neither in adult females nor in nymphs. On the other hand, no day-night changes were detected in any experimental group under constant light. These results suggest that the change in rhabdom size between day and night is an adaptation to the photic environment that is controlled mainly by the light-dark (day-night) cycle. However, the change in male adults is induced by an endogenous circadian clock.     

Mother–young distance in Japanese Black cattle at pasture

Distance between dam and offspring (1–121 days old) in a herd of Japanese Black cattle (Bos taurus) grazing a tropical grass (Paspalum notatum) pasture (1.5 ha) was investigated during 7-h grazing periods over grazing seasons from May (spring) to October (autumn). The mother–young distance was not constant throughout the grazing period, repeatedly increasing and decreasing. Although significant periodicity was always detected in the mother–young distance, there was no consistent dominant cycle, indicating the complexity of the within-day pattern of mother–young distance. The mean mother–young distance over the grazing period increased as a calf aged, reaching a plateau at an age of about 33 days. The mean distance of a calf from its mother was usually shorter than that from a non-mother cow, with the difference between the mean distances decreasing sharply until a calf became about 35 days old. The results and literature show that mutual independence of mother and young rapidly develops in the first 30–50 days after parturition. Electronic Publication     

mGluR2 postsynaptically senses granule cell inputs at Golgi cell synapses

In the cerebellar circuit, Golgi cells are thought to contribute to information processing and integration via feedback mechanisms. In these mechanisms, dynamic modulation of Golgi cell excitability is necessary because GABA from Golgi cells causes tonic inhibition on granule cells. We studied the role and synaptic mechanisms of postsynaptic metabotropic glutamate receptor subtype 2 (mGluR2) at granule cell-Golgi cell synapses, using whole-cell recording of green fluorescent protein-positive Golgi cells of wild-type and mGluR2-deficient mice. Postsynaptic mGluR2 was activated by glutamate from granule cells and hyperpolarized Golgi cells via G protein-coupled inwardly rectifying K+ channels (GIRKs). This hyperpolarization conferred long-lasting silencing of Golgi cells, the duration and extents of which were dependent on stimulus strengths. Postsynaptic mGluR2 thus senses inputs from granule cells and is most likely important for spatiotemporal modulation of mossy fiber-granule cell transmission before distributing inputs to Purkinje cells.     

Convenient method for determining the absolute configuration of chiral alcohols with racemic 1H NMR anisotropy reagent,M(alpha)NP acid: use of HPLC-CD detector

A convenient method for determining the absolute configuration of chiral secondary alcohols using the racemic NMR anisotropy reagent, (+/-)-2-methoxy-2-(1-naphthyl)propionic acid [(+/-)-M(alpha)NP acid], and an HPLC-CD detector was developed. The method was successfully applied to some chiral alcohols derived from (-)-alpha-santonin.     

Polyphenols from some foodstuffs as inhibitors of ovalbumin permeation through caco-2 cell monolayers

Some spices showed high inhibitory activity against ovalbumin permeation through Caco-2 cell monolayers. Pimentol from allspice, rosmarinic acid and luteolin-7-O-beta-glucuronide from thyme, quercetin-3-O-beta-glucuronide from coriander and rutin from tarragon were identified as the active principles. A structure-activity relationship study among the active isolates and their related compounds indicated that the presence of a catechol structure played an important role in the inhibitory activity of each compound.     

Isolation and characterization of aromatics-degrading microorganisms from the gut of the lower termite Coptotermes formosanus

We isolated aromatics-degrading bacteria from the gut of a lower termite, Coptotermes formosanus, using a mineral salt medium containing various aromatic compounds as the sole carbon source. Two species, Burkholderia sp. strain VE22 and Citrobacter sp. strain VA53, were isolated by aerobic enrichment culture with veratraldehyde and vanillin, respectively. Strain VA53 could also grow and metabolize vanillin anaerobically.     

Diversity and rarity hotspots and conservation of butterfly communities in and around the Aokigahara woodland of Mount Fuji,central Japan

In central Japan, Aokigahara woodland is considered to be one of the most natural areas around Mount Fuji and a core area in the conservation of the biodiversity of Mount Fuji. We chose butterflies as an indicator species of biodiversity and examined six communities in and around the woodland in 2000 using transect counts to examine and search for diversity and rarity hotspots and their associated landscapes. The results showed that butterfly species richness and species diversities H 1/ were significantly higher in forest-edge sites than in forest-interior and/or open-land sites, and variation in the total number of species among these three landscape types was well accounted for by ecologically specialist species, such as landscape specifics, oligovoltines, narrow diet feeders and low-density species. Thus, the species regarded as vulnerable to extinction, including Red List species, were observed more often in forest-edge sites than in forest-interior and/or open-land sites. As a result, in the study area, diversity and rarity hotspots were found in forest-edge landscapes. The reasons why butterfly diversity and rarity hotspots were established in forest-edge landscapes were analyzed and interpreted from several points of view, including disturbance level, landscape elements and plant species richness. From these results, and the fact that some species were confined to forest-interior sites, we conclude that it is very important to conserve and manage forest-edge habitats (considered to be semi-natural) as well as forest-interior habitats (considered to be the most natural) to maintain the diversity of butterfly communities and preserve the various types of threatened species in and around the Aokigahara woodland.     

Development of a D-alanine sensor for the monitoring of a fermentation using the improved selectivity by the combination of D-amino acid oxidase and pyruvate oxidase

A D-alanine (D-Ala) sensor for the monitoring of a fermentation process was developed using flow injection analysis (FIA). The FIA system consisted of a D-amino acid oxidase (D-AAOx) reactor, a Pyruvate oxidase (PyOx) electrode and a contrast electrode in the flow cell, and through the oxidation of D-amino acids in the D-AAOx reactor, pyruvic acid was formed only from D-Ala. The pyruvic acid was further oxidized with PyOx via the D-AAOx reaction. The amount of oxygen consumed in the PyOx reaction was proportional to the amount of D-Ala. It was possible to continuously repeat the assay up to 60 times at pH 6.8 and a flow rate of 0.18-ml min(-1). A linear relationship was obtained in the range of 0.1-1 mM D-Ala with a correlation coefficient of 0.987 and the detection limit was 0.05 mM. The relative standard deviation (R.S.D.) was 4.9% (n=5) for 0.5 mM D-Ala. The D-Ala content in some fish sauces was also determined using the proposed sensor system. The results obtained indicated a linear relationship between the amounts of D-Ala determined by the proposed sensor system and the conventional method. From the results, even if the substrate specificity of the enzyme (D-AAOx) was low, it was evident that the concentration of the original material (D-Ala) could be determined specifically when the first reaction product was changed by the second reaction (PyOx).