Metabotropic glutamate receptors are associated with non-synaptic appendages of unipolar brush cells in rat cerebellar cortex and cochlear nuclear complex

Unipolar brush cells (UBCs) are a class of small neurons that are densely concentrated in the granular layers of the vestibulocerebellar cortex and dorsal cochlear nucleus. The UBCs form giant synapses with individual mossy fibre rosettes on the dendrioles which make up their brush formations and are provided with numerous, unusual non-synaptic appendages. In accord with the glutamatergic nature of mossy fibres, our previous post-embedding immunocytochemical studies indicated that various ionotropic glutamate receptor subunits are localized at the post-synaptic densities of the giant synapses, whereas the non-synaptic appendages are immunonegative. On the contrary, the metabotropic glutamate receptors mGluR1alpha and mGluR2/3 are situated at the non-synaptic appendages and are lacking at the post-synaptic densities. Other authors, however, have shown that antibodies to these metabotropic receptors stain both appendages and post-synaptic densities. In the present study, we have re-evaluated the distribution of metabotropic glutamate receptors in the UBCs of the cerebellum and the cochlear nuclear complex by light and electron microscopic pre-embedding immunocytochemistry with subtype-specific antibodies. We confirm that UBCs dendritic brushes are densely immunostained by antibody to mGluR1alpha particularly in the cerebellum and that antibody to mGluR2/3 labels at least a percentage of the UBC brushes in both the cerebellum and cochlear nuclei. At the ultrastructural level, it appears that mGluR1alpha and mGluR2/3 immunoreactivities are not associated with the post-synaptic densities of the giant mossy fibre-UBC synapses, but instead are concentrated on the non-synaptic appendages of the cerebellar UBCs. The non-synaptic appendages, therefore, may be an important avenue for regulating the excitability of UBCs and mediating glutamate effects on their still unknown intracellular signal transduction cascades. We also show that the pre-synaptic densities of UBC dendrodendritic junctions are mGluR2/3 positive. As previously demonstrated, antibodies to mGluR1alpha and mGluR2/3 label subsets of Golgi cells. Antibody to mGluR5 does not stain UBCs in the cerebellum and cochlear nucleus and reveals the somatodendritic compartment of Golgi cells situated in the core of the cerebellar granular layer, whilst cochlear nucleus Golgi cells are mGluR5 negative.     

Significance of attached cyanobacteria relevant to the occurrence of musty odor in Lake Kasumigaura

The microorganisms and compounds causing musty odor in the second largest lake in Japan, Lake Kasumigaura, where the water is used for drinking, fisheries and agricultural purposes, were examined during the severe occurrence of musty odor in 1989 and 1990. This study was undertaken to determine the microorganisms and their metabolites responsible for the musty odor. Phormidium tenue, which has been reported to be the main contributor of the odor in Lake Kasumigaura, was isolated. Furthermore, four monoxenic strains of the odor producing attached cyanobacteria, Phormidium viscosum, Lyngbya allorgei, Oscillatoria splendida and Phormidium uncinatum, were isolated from submerged rocks and sediments in the lake. All of the four attached strains produced only geosmin, which was confirmed by gas chromatograph/mass spectrometer analysis, in the monoxenic cultures. In particular, we confirmed for the first time that P. viscosum, L. allorgei and P. uncinatum produced geosmin. Both the planktonic Phormidium tenue, a well known 2-methylisoborneol (MIB) producer and geosmin-producing attached cyanobacteria were closely associated with the occurrence of musty odor in Lake Kasumigaura.     

Localization of the neuromedin K receptor (NK3) in the central nervous system of the rat

The distribution of the neuromedin K receptor (NK3; NKR) in the central nervous system was investigated in the adult rat by using in situ hybridization and immunohistochemical techniques. The rabbit anti-NKR antibody was raised against a bacterial fusion protein containing a C-terminal portion of NKR and affinity purified with a Sepharose 4B column conjugated to the fusion protein. Immunoblot analysis was performed to test the reactivity and specificity of the antibody. Crude membrane was prepared from cDNA-transfected Chinese hamster ovary (CHO) cells expressing each of the rat NKR, substance P receptor (NK1; SPR), and substance K receptor (NK2; SKR) and from the hypothalamus, cerebral cortex, and cerebellum. Immunoreactive bands were observed specifically in the NKR-CHO cells, hypothalamus, and cerebral cortex but not in the SPR- or SKR-CHO cells, nor in the cerebellum. Molecular weights of the immunoreactive bands ranged from 73 to 89 kDa and from 59 to 83 kDa in the NKR-CHO cells and tissues, respectively. The distribution of NKR-like immunoreactivity coincided with that of NKR mRNA. The expression of NKR was indicated on neuronal cell bodies and dendrites. NKR was found to be expressed intensely or moderately in neurons in the glomerular and granule cell layers of the main olfactory bulb; glomerular and mitral cell layers of the accessory olfactory bulb; layers IV and V of the cerebral neocortex; medial septal nucleus; nucleus of the diagonal band; bed nucleus of the stria terminalis; globus pallidus; ventral pallidum; paraventricular nucleus; supraoptic nucleus; zona incerta; dorsal, lateral, and posterior hypothalamic areas; amygdaloid nuclei; medial habenular nucleus; ventral tegmental area; midbrain periaqueductal gray; interpeduncular nuclei; substantia nigra pars compacta; linear, median, dorsal, and pontine raphe nuclei; posteromedial tegmental nucleus; sphenoid nucleus; nucleus of the solitary tract; intermediate and rostroventrolateral reticular nuclei; and lamina II of the caudal spinal trigeminal nucleus and spinal dorsal horn. These findings are discussed in relation to the physiological functions associated with neuromedin K.     

Correspondence among PL measurement, MBIC measurement and defect delineation in polycrystalline cast-Si solar cells

We report the correspondence between the photoluminescence (PL) measurement, monochromatic-light-beam-induced current (MBIC) measurement and defect delineation in polycrystalline cast-Si solar cells. It was found that the peak of the band-edge PL emission in the hydrogenerated and non-hydrogenerated cast-Si shifted from 1.093 eV in the single crystalline CZ-Si to 1.075 eV at room temperature and the band-edge PL mapping corresponded with the MBIC mapping and defect delineation pattern if excluding the surface damages delineated by the MD-1 etchant.     

Effects of the creep deformation on the fractal dimension of the grain boundaries in an austenite steel

The change in the fractal dimension of the grain boundaries during creep was investigated using an austenitic SUS304 steel at 973 K. The fractal dimension of the grain-boundary surface profile (the fractal dimension of the grain boundaries, D, 1 < D < 2) in the plane parallel to the tensile direction (in the parallel direction) and in the transverse direction, was examined on specimens deformed up to rupture (about 0.30 creep strain). Grain boundaries became serrated and the fractal dimension of the grain boundaries increased with increasing creep strain, because the density of slip lines which formed ledges and steps on grain boundaries increased as the creep strain increased. The increase in the fractal dimension due to creep deformation was slightly larger under the higher stress (118 MPa) than under the lower stress (98 MPa), while the increase of the fractal dimension with strain was a little larger in the specimens tensile-strained at room temperature (293 K) than in the crept specimens. These results were explained by the grain-boundary sliding and the diffusional recovery near grain boundaries, which lowered the increase of the fractal dimension with the creep strain. The fractal dimension of the grain boundaries in the parallel direction was slightly larger than that in the transverse direction in both creep at 973 K and tensile deformation at room temperature, especially at the large strains. This could be correlated with the shape change of the grains by creep or plastic deformation. Grain-boundary cracks were principally initiated at grain-boundary triple junctions in creep, but ledges, steps and carbide precipitates on serrated grain boundaries were not preferential nucleation sites for the cracks.     

Application of AC plasma display panels to radiation detectors

Radiation detector proposals that use plasma display panels are rare. In this work, we confirmed a radiation detector that uses plasma display panels that are focused on the breakdown voltage shift in the ramp waveform. We adapted the cell structures, gas contents, and waveforms of plasma display panels (AC‐PDPs) for radiation detectors. Hard X‐rays and gamma rays induce electron emission into the discharge gas, resulting in generating electrons, electron multiplication, and charge accumulation on dielectrics. The radiation dose rate of hard X‐rays and gamma rays (Cs137) is measured as a breakdown voltage shift between anodes and cathodes. For gamma rays, the detection sensitivity in this experiment is not as high as in the case of hard X‐rays, but the detector can locate gamma rays. These results suggest that adapted AC‐PDPs can detect both hard X‐rays and gamma rays and can be used in a large two‐dimensional radiation detector.     

A convenient preparative method of 3-hydroxy acids,and the reaction of 3-hydroxy acids with acidic materials

3-Hydroxy acids were synthesised in good yield from ketones and carboxylic acids using lithium naphthalenide in the presence of diethylamine. From cyclohexanone and propionic acid, 2-(1′-hydroxycyclohexan-1′-yl) propionic acid ( I ) was obtained in 98.3% yield. 3-Hydroxy acids were treated with various acidic materials to give 3,4-unsaturated carboxylic acids and γ-butyrolactones. From the reaction of ( I ) with p-toluenesulphonic acid or potassium bisulphate, 2-(cyclohexen-1′-yl) propionic acid ( II ) (a 3,4-unsaturated acid) was obtained (yield 98%), and with 97% sulphuric acid 2-(1′-hydroxycyclohexan-1′-yl) propionic acid lactone ( III ) was formed (93% yield). Several new γ-butyrolactones were obtained in good yield by this method.     

Enzymatic synthesis of N-acyl-l-amino acids in a glycerol-water system using acylase I from pig kidney

N-Medium- and long-chain acyl-l-amino acids were enzymatically synthesized from the corresponding l-amino acids and fatty acids using a reverse hydrolysis. Enzymes that are suitable for the synthetic reaction of N-acyl-l-amino acids were screened on the basis of hydrolytic activity toward N-lauroyl-l-glutamic acid as an indicator. Acylase I from pig kidney (EC 3.5.1.14) showed the highest N-acyl-l-amino acid hydrolytic activity among 57 commercially available enzymes tested. Acylase I effectively catalyzed the synthesis of N-lauroyl-l-amino acids except for N-lauroyl-l-proline and N-lauroyl-l-tyrosine in a glycerol-water system. Under the optimized reaction conditions, N-lauroyl-l-arginine and N-lauroyl-l-glutamic acid were obtained in conversions of 82 and 44%, respectively. The equilibrium constants calculated from the conversion obtained were 5.6, 15.4, 18.0, and 39.4 for the syntheses of N-lauroyl-l-glutamic acid, N_α-lauroyl-l-lysine, N-lauroyl-l-glutamine, and N-lauroyl-l-methionine, respectively. N-Acyl-l-arginines with myristic acid and palmitic acid as the fatty acid were also synthesized using acylase I.     

Fracture Process of Silicon Carbide Fiber-Reinforced Glasses

This paper evaluates the fracture process for fiber-reinforced glasses under tensile loading. Two types of unidirectionally aligned Nicalon SiC-fiber-reinforced glass with different fiber coatings were examined. One channel acoustic emission (AE) measurement was employed during the tensile tests. Probabilistic fracture analysis as well as the replication technique were used to investigate the relation between the AE signals and fracture processes. The AE technique proved to be an effective method for observing fracture processes of the material systems studied. The fracture process could be distinguished in terms of the AE amplitude. AE signals with high amplitudes corresponded to fiber breaking; AE signals with low amplitudes corresponded to matrix cracking, interfacial debonding, and fiber pullout. In the well-toughened material studied the reinforcing fibers would break extensively over 75% load of the ultimate strength.