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Sacoglossan sea slugs retain the chloroplasts from food algae in their cells (kleptoplasty) and obtain the photosynthetic products, but the capability of kleptoplasty differs among species. One evolutionary hypothesis for kleptoplasty is that the family Volvatellidae is the ancestral sacoglossan lineage in which kleptoplasty arose, but this is based on ambiguous phylogenetic relationships. To test this hypothesis, we analyzed sacoglossan phylogeny for concat- enated sequences (approximately 4000 bp) of nuclear (18S rRNA) and mitochondrial (CO1, trnV, and 16S rRNA) genes of 18 sacoglossan species, using neighbor-joining, maximum parsimony, maximum likelihood, and Bayesian methods. The resultant phylogenetic trees clearly revealed monophyly of the order Sacoglossa (including the debatable genus Cylindrobulla), which contained two sister clades: the shelled sacoglossan group (Oxynoacea Cylindro- bulla) and the non-shelled group (Plakobranchacea). The family Volvatellidae was in a derived position within the Oxynoacea. The most parsimonious rearrangement of the character states of kleptoplasty on the phylogenetic tree suggested that (1) kleptoplasty was acquired at the basal position of the Sacoglossa (including Cylindrobulla) as non-functional kleptoplasty, (2) functional kleptoplasty was gained in the Plakobranchacea clade, and (3) non-functional kleptoplasty was lost in the Volvatellidae lineage in the Oxynoacea clade.

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.

The multiarmed sea star Coscinasterias acutispina generally has 7-10 arms and 2-5 madreporites. It is known to be able to reproduce by asexual fission, and we have previously observed that this species also has the ability to reproduce sexually; however, there has been no report until now of spawning in this species. We succeeded in establishing a long-term culture of juveniles produced by artificial fertilization. Twelve months after the completion of metamorphosis, three individuals had six arms of the same length and a madreporite. At this time, fission occurred in two of these individuals, while the remaining individual underwent fission four months later. Each sea star divided into two halves, provided with three arms each. Thereafter, four or five new arms and two or four madreporites were formed anew in each of the six daughter sea-stars, so that by 30 days after the first fission the number of arms and madreporites in each was similar to that in adults. A second fission occurred in four of these six individuals, four or five months after the first fission, and in three of them the plane of division was the same as that of the first fission. The original three individuals eventually proliferated to 12 by undergoing fission. All individuals had fully developed gonads by 1-3 months after the second fission. Some of them eventually spawned under laboratory culture, and the resulting larvae metamorphosed into juveniles. Our observations demonstrate that individuals of C. acutispina possess the potential for both sexual and asexual reproduction.

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.

Ascorbic acid (AsA) is an essential nutrient for humans as they lack its biosynthesizing key enzyme. Its absorption mechanism in small intestinal epithelial cells still remains to be resolved. In this study, the transport mechanisms functioning on the uptake of AsA and its oxidized form, dehydroascorbic acid (DHA), were investigated using rat small intestinal epithelial cell line IEC-6. Both AsA and DHA were accumulated in the cells in time- and concentration-dependent manners, but their absorption kinetics were apparently different. The saturability of AsA uptake was shown at a considerably lower concentration in IEC-6 cells as well as other mammalian cells, indicating that this absorption was mediated by a specific transporting carrier. The absorption efficiency of AsA was about 1/5-1/10 that of DHA at the same concentration range and, moreover, the uptake of DHA was almost comparable to that of 2-deoxy-D-glucose, an alternative of glucose. The uptake of AsA was diminished by the removal of sodium ion, but not by the addition of glucose, whereas that of DHA was sodium ion-independent and effectively inhibited by glucose. In addition, phlorizin and cytochalasin B, which are blockers of glucose transporters, interfered the uptake of DHA more efficiently than that of AsA. These results indicate that there are at least two distinct transport systems of vitamin C in rat small intestinal epithelial cells; AsA is transported by a specific transporter and DHA is mainly transported by glucose transporter(s).

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.

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.

The inwardly rectifying ATP-regulated K(+) channel with an inward conductance of about 90 pS in the surface membrane of cultured opossum kidney proximal tubule (OKP) cells is activated at least in part by protein kinase A (PKA). In this study, we examined the effects of protein serine/threonine phosphatase types 1 (PP-1) and 2A (PP-2A) on activity of the K(+) channel using the patch-clamp technique. In cell-attached patches, channel activity was enhanced by the application of okadaic acid (OA, 1 microM), a membrane-permeable inhibitor of PP-1 and PP-2A, to the bath solution. This enhancement was abolished by the pretreatment of cells with KT5720 (200 nM), a specific inhibitor of PKA. In inside-out patches, channel activity which could be maintained in the presence of ATP (3 mM) in the bath solution was also increased by the addition of OA (1 microM), and the OA-induced increase in channel activity was partially prevented in the presence of KT5720 (200 nM). Direct application of either PP-1 (1 U/ml) or PP-2A (1 U/ml) to the cytoplasmic surface of the patch membrane inhibited channel activity maintained by ATP (3 mM) in inside-out patches. Moreover, channel activity stimulated by PKA (20 nM) in the presence of ATP (3 mM) was also inhibited by the application of either PP-1 (1 U/ml) or PP-2A (1 U/ml). These results indicate that the OA-sensitive protein phosphatase is involved in the regulation of channel activity, and suggest that both PP-1 and PP-2A are candidates responsible for the inhibition of channel activity through dephosphorylation of the PKA-mediated protein phosphorylation.

Eight dopamine receptor-like cDNA clones were isolated from the carp (Cyprinus carpio) retina and four dopamine receptor-like cDNA clones were isolated from the European eel (Anguilla anguilla) retina. These cDNA clones show high sequence and structural homology to the known dopamine receptor subtypes. The sequence similarity and phylogenetic analysis revealed that five subtypes (D1A3, D1A4, D1B, D1C and D1X) in the carp retina and four subtypes (D1A1, D1A2, D1B and D1C) in the eel retina are D1-like receptor subtypes, and three (D2, D4A and D4B) in the carp retina are D2-like receptor subtypes; no D2-like receptor was found in the eel. Carp D1A3 and D1A4, carp D4A and D4B, and eel D1A1 and D1A2 are highly homologous pairs of receptors which show significant, domain-specific differences to each other and to their species homologues. The structure of the third cytoplasmic loop in the carp D1X receptor was particularly different from the other D1-like receptors. The implications of these structural differences in terms of dopamine receptor activation and signalling are discussed. It is suggested that the known diverse physiological and pharmacological effects of dopamine on the retinal neurones are likely to be mediated through these multiple receptor subtypes which may be coupled to different signal transduction pathways.

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.

L-glutamate, the main excitatory synaptic transmitter in the retina, is released from photoreceptors and evokes responses in second-order retinal neurons (horizontal, bipolar cells) which utilize both ionotropic and metabotropic types of glutamate receptors. In the present study, to elucidate the functional roles of glutamate receptors in synaptic transmission, we have identified a specific ionotropic receptor subunit (GluR4) and determined its localization with respect to photoreceptor cells in the outer plexiform layer of the goldfish retina by light and pre-embedding electron-microscopical immunocytochemistry. We screened antisera to mammalian AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate)-preferring ionotropic glutamate receptors (GluR 1-4) of goldfish retina by light- and electron-microscopical immunocytochemistry. Only immunoreactive (IR) GluR4 was found in discrete clusters in the outer plexiform layer. The cones contacted in this manner were identified as long-wavelength ("red") and intermediate-wavelength ("green") cones, which were strongly immunoreactive to monoclonal antibody FRet 43 and antisera to goldfish red and green-cone opsins; and short-wavelength ("blue") cones, which were weakly immunoreactive to FRet 43 but strongly immunoreactive with antiserum to blue-cone opsin. Immunoblots of goldfish retinal homogenate with anti-GluR4 revealed a single protein at M(r) = 110 kDa. Preadsorption of GluR4 antiserum with either the immunizing rat peptide, or its goldfish homolog, reduced or abolished staining in retinal sections and blots. Therefore, we have detected and localized genuine goldfish GluR4 in the outer plexiform layer of the goldfish retina. We characterized contacts between photoreceptor cells and GluR4-IR second-order neurons in the electron microscope. IR-GluR4 was localized to invaginating central dendrites of triads in ribbon synapses of red cones, semi-invaginating dendrites in other cones and rods, and dendrites making wide-cleft basal junctions in rods and cones; the GluR4-IR structures are best identified as dendrites of OFF-bipolar cells. The results of our studies indicate that in goldfish retina GluR4-expressing neurons are postsynaptic to all types of photoreceptors and that transmission from photoreceptors to OFF-bipolars is mediated at least in part by AMPA-sensitive receptors containing GluR4 subunits.

The anti-hepatic cancer effects of three free polyunsaturated fatty acids (linoleic, alpha-linolenic, and gamma-linolenic acids) dissolved in an oily lymphographic agent, Lipiodol Ultra-Fluid (Lipiodol), following intrahepatic arterial administration were examined using a rabbit liver cancer model, VX-2. The tumor was inoculated into the subcapsular parenchyma of the liver of rabbits, and Lipiodol alone or Lipiodol containing each one of the free fatty acids was administered into the hepatic artery 14 days after inoculation. The rabbits were sacrificed 7 days after administration. Lipiodol containing one of the fatty acids selectively remained in the tumor area. Although VX-2 tumor grew extensively in both the untreated group and the group that received Lipiodol alone, growth of VX-2 tumor was greatly suppressed in the group that received Lipiodol containing the free fatty acid. Pathological observation also showed that Lipiodol containing the free fatty acid had an anticancer effect on VX-2 tumor growing in the liver of rabbits. Average survival days in the group treated with Lipiodol containing gamma-linolenic acid were significantly prolonged compared with those in the control groups. Although growth rates of the tumor at the death of rabbits were large in the control groups, VX-2 tumor shrank at death of five rabbits of six in the group treated with Lipiodol containing gamma-linolenic acid. These results suggest that the intrahepatic arterial administration of Lipiodol containing the free fatty acids is an effective method of delivery of these fatty acids as anticancer agents.

Two closely related species of aeolid nudibranchs, Eubranchus misakiensis and E. horii, were found abundantly on the same leaves of seaweeds, Ecklonia kurome. Three thecata hydroid species also grew in large numbers on the surface of the weeds. E. misakiensis occurred always only on colonies of Obelia geniculata, with E. horii always only on colonies of Plumularia filicaulis japonica. Neither aeolid was found on Orthopyxis platicarpa. These field observations and results of choice experiments demonstrate considerable feeding segregation in the two aeolids.

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.

La reponse hypertensive a des injections s.c. d'extrait de rein n'ayant initialement que peu ou pas d'effet sur la tension arterielle s'accroit progressivement avec la duree du traitement.