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The effects of two distinct patterns of light stimulus, steady and flicker, on cone photomechanical movements (PMMs) in the Xenopus laevis retina were investigated. For both patterns studied, the effects on PMMs were assessed by quantitative analysis of the cone positions in the outer retina. Steady light adaptation was found to be equally effective as flicker in causing cone contractions. This was unlike the situation previously found in the cyprinid fish retina, in which flickering light was significantly more effective than steady. This difference could be related to the light-evoked response characteristics and circuitry of dopaminergic retinal neurones in the two vertebrate classes. The role of dopamine and other possible neuromodulator(s) in light adaptive control of vertebrate retinae is discussed.

Catalytic combustion is an ultralow NOx combustion method, so it is expected that this method will be applied to a gas turbine combustor. However, it is difficult to develop a catalytic combustor because catalytic reliability at high temperature is still insufficient. To overcome this difficulty, we designed a catalytic combustor in which premixed combustion was combined. By this device, it is possible to obtain combustion gas at a combustion temperature of 1300°C while keeping the catalytic temperature below 1000°C. After performing preliminary tests using LPG, we designed two types of combustor for natural gas with a capacity equivalent to one combustor used in a 20 MW class multican-type gas turbine. Combustion tests were conducted at atmospheric pressure using natural gas. As a result, it was confirmed that a combustor in which catalytic combustor segments were arranged alternately with premixing nozzles could achieve low NOx and high combustion efficiency in the range from 1000°C to 1300°C of the combustor exit gas temperature.

X‐Ray fluorescence analysis of five heavy elements (Pb, Pt, W, Sn, and Ag) was performed using the portable synchrotron MIRRORCLE‐20. The characteristic K X‐rays (Kα and Kβ) were clearly observed for all of the five samples. This verifies that MRRORCLE‐20 generates X‐rays of energy higher than that of the Pb K absorption edge (88.0 keV). In addition to these characteristic K X‐rays, several peaks with short lifetimes were also observed in all the samples.

The possible role of nitric oxide (NO) as a novel light adaptive neuromodulator of cone plasticity (photomechanical movements) in retinae of two contrasting species of fish (freshwater carp and marine bream) and an example of an amphibian (Xenopus laevis) was studied pharmacologically by cytomorphometric measurements. Application of a NO donor [S-nitroso-N-acetyl- d , l -penicillamine] (500–700 μM) to dark-adapted retinae induced contraction of cones with an efficiency (CE) relative to full light adaptation of around 54% in all three species. Pretreatment with a NO scavenger [2-(4-Carboxyphenyl)-4,4,5,5-tetrametylimidazoline-1-oxil-3-oxide] (30–35 μM) produced a consistent significant inhibition of the light adaptation-induced cone contraction (CE = 15–20%). These results strongly suggest the involvement of endogenous NO in the cone contractions that occur in freshwater and marine fish and amphibian retinae as a part of the light adaptation process.

Fourteen new sesquiterpenes of the drimane series dendocarbins A--N (1--14) were obtained from ethanol extracts of the Japanese nudibranch Dendrodoris carbunculosa, together with two known compounds, isodrimeninol (15) and 11-epivaldiviolide (16). All structures were elucidated mainly from spectral data, and most of these sesquiterpenes were found to exhibit cytotoxicity. In addition, isodrimeninol (15), the major sesquiterpene of this animal, was found to have a sharp peppery taste.

21 pages, 7 figures, 3 tables, The small spotted dogfish Scyliorhinus canicula and the blackmouth dogfish Galeus melastomus, whose depth distributions overlap in the upper part of the slope (c. 500 m depth), where they have access to the same prey community, have well-developed eyes and a pure-rod retina with a single layer of photoreceptors. Interspecific differences in rod outer segment length (LROS) within retinal regions were found. In the periphery and the retinal centre G. melastomus showed a LROS 24 and 30% longer, respectively, than S. canicula and, therefore, a potential for increased sensitivity. In both species longer LROS were always found in correspondence with the retinal centre where the ganglion cell topography formed a horizontal meridian that allowed for better discrimination of the horizon in the visual field. In this area LROS reached 53·4±4·1μm in S. canicula and 77·1±10·5μm in G. melastomus against 46·3±4·2μm and 61·1±10·1μm in the retinal periphery. No significant differences were recorded in LROS and rod density during growth. In both species, a rapid increase of theoretical visual acuity was found to be related to an increase in fish LT and lens size. Visual acuity ranged between 1·7 and 3 cycles degree-1 in S. canicula and 2·4 and 4·2 in G. melastomus. The G. melastomus rod visual pigment showed the characteristic spectral adaptation to vision in deep-water (λmax of 481 nm), but was also well placed to detect the bioluminescence of some of its main prey species. In S. canicula the visual pigment absorption (λmax of 496 nm) was more typical of shallow water living fishes. The opsin sequences of the two visual pigments are discussed and key amino acid sites were identified where sequence changes could be responsible for the spectral absorption differences between the two species. The possible relationship between LROS, visual acuity, visual pigment absorption, depth distribution and feeding behaviour are discussed, This study was made possible by a postgraduate fellowship to AB from the Ministry of Research and Science, Spain. The work at the IMC was supported by grants from the EU (STRIDE programme) and the Sardinian Regional Government. Fieldwork was supported by a grant from the Ministry of Research and Science (CICYT-AMB93-0283). We are grateful to J. Cartes for his helpful suggestions and comments during the preparation of the manuscript and S. Collin for his useful comments that greatly improved the manuscript. Special thanks to A. Siddu for her technical assistance at the IMC and to the fishermen of Oristano who helped to collect the Sardinian samples

The role of nitric oxide (NO) as a novel neurochemical mechanism controlling light adaptation of the outer retina is discussed by considering mainly published results. The emphasis is on the retinae of fishes and amphibia, but some data from the mammalian (rabbit) retinae have also been included for completeness. In the fish retina, application of NO donors in the dark caused light–adaptive photomechanical movements of cones. The normal effect of light adaptation in inducing cone contractions was suppressed by pretreatment of retinae with an NO scavenger. NO donors modulated horizontal cell activity by uncoupling the cells' lateral gap junctional interconnections and enhancing negative feedback to cones, again consistent with a light–adaptive role of NO. Direct evidence for light adaptation–induced release of NO has been obtained in fish (carp) and rabbit retinae. The results strongly suggest that control of retinal light adaptation is under multiple neurochemical control, with NO and dopamine having an interactive role.

Neurobiology of retinal dopamine is reviewed and discussed in relation to degenerative states of the tissue. The Introduction deals with the basic physiological actions of dopamine on the different neurons in vertebrate retinae with an emphasis upon mammals. The intimate relationship between the dopamine and melatonin systems is also covered. Recent advances in the molecular biology of dopamine receptors is reviewed in some detail. As degenerative states of the retina, three examples are highlighted: Parkinson's disease; ageing; and retinal dystrophy (retinitis pigmentosa). As visual functions controlled, at least in part, by dopamine, absolute sensitivity, spatial contrast sensitivity, temporal (including flicker) sensitivity and colour vision are reviewed. Possible cellular and synaptic bases of the visual dysfunctions observed during retinal degenerations are discussed in relation to dopaminergic control. It is concluded that impairment of the dopamine system during retinal degenerations could give rise to many of the visual abnormalities observed. In particular, the involvement of dopamine in controlling the coupling of horizontal and amacrine cell lateral systems appears to be central to the visual defects seen.

Catalytic combustion is an ultra low NOx combustion method, so it is expected that this method will be applied to gas turbine combustor. However, it is difficult to develop catalytic combustor because catalytic reliability at high temperature is still insufficient. To overcome this difficulty, we designed a catalytic combustor in which premixed combustion was combined. By this device, it is possible to obtain combustion gas at a combustion temperature of 1300°C while keeping the catalytic temperature below 1000°C. After performing preliminary tests using LPG, we designed two types of combustors for natural gas with a capacity equivalent to 1 combustor used in a 20MW–class multi–can type gas turbine. Combustion tests were conducted at atmospheric pressure using natural gas. As a result, it was confirmed that a combustor in which catalytic combustor segments were arranged alternately with premixing nozzles could achieve low NOx and high combustion efficiency in the range from 1000°C to 1300°C of the combustor exit gas temperature.

Summary We examined the expression of the transglutaminase 1 (TGase 1) gene IN frozen sections of normal and psoriatic epidermis by means of non-radioactive in situ hybridization with digoxigenin-labelied cRNA probes. TGase l mRNA was expressed in the granular layer of normal epidermis. regardless of ortho-or hyperkeratosis. However, in psoriatic epidermis. TGasel mRNA was detected in the suprabasal spinous layer, but not in the subcorneal layer. These results indicate that TGase 1 gene expression is limited to the last stage of keratinization in normal epidermis and this regulation is disturbed in psoriasis.

Summary The dietary effect of various amounts of magnesium on cholesterol-induced atherosclerosis of rabbits was investigated. There was a significant enhancement of the lipid deposition in the aorta of rabbits fed a magnesium-deficient diet containing cholesterol. However, this study failed to demonstrate any retarding effect from the feeding of magnesium excess diets on aorta lipid deposition.