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Species of the genus Elysia Risso, 1818 have relatively few external characters useful for species identification, and features such as papillae and/or color markings on the body surface are often used to classify and identify species. Elysia atroviridis Baba, 1955 and E. setoensis Hamatani, 1968, for example, have been described as distinct based mainly on such characters. Close examinations of 46 specimens identifiable as either species collected from nine localities in Japan revealed that many specimens exhibited mixed features of the two species. Detailed comparisons of radular morphology could also not differentiate the two species. With phylogenetic analyses based on COI and 16S rRNA (1072 bp in total), all of the examined specimens formed a single clade with very little variation among specimens. The AMOVA of the specimen haplotypes showed there was no significant genetic differentiation in relation to differences in external morphology, geographic region, or algal host. Our results indic...

Many sacoglossan sea slugs utilize chloroplasts ingested from food algae for photosynthesis (functional kleptoplasty), and the extent and duration of kleptoplast retention differs greatly among sacoglossan species. Although most recent studies focus on the genetic, microscopic, or physiological mechanisms responsible for this unique phenomenon, its effects on the life history traits of sacoglossans have not been fully explored. To study the effects of light conditions on survival and weight retention, adult individuals of two sacoglossan species, Elysia trisinuata and Plakobranchus ocellatus (‘black type'), were reared under light conditions (a 14-hour light: 10-hour dark photoperiod with an irradiance level of 28 µmol m−2s−1) or complete darkness for 21 days. There was no significant difference in the survival rate between the light and dark treatments for E. trisinuata, and its wet weight relative to the initial weight was smaller in the light than in the dark. However, both the survival and relative weights were greater in the light than dark for P. ocellatus. Based on the fluorescent yield measurement using pulse-amplitude-modulated fluorometry, the retention duration of functional chloroplasts was longer (>17 days) for P. ocellatus than E. trisinuata (P. ocellatus benefits from photosynthesis for survival and growth, whereas E. trisinuata does not under starved conditions. This interspecific difference is likely related to the period of functional chloroplast retention.

An endoparasitic platyhelminth from six species of sacoglossan opisthobranchs was collected at several localities of temperate to subtropical waters in Japan. Poecilostomatoid copepods (all species of Splanchnotrophidae and several species of Philoblennidae) and a few digenean flukes had been the only endoparasitic metazoans known for opisthobranch hosts. The newly discovered parasite was 1 to 15 mm in length and had no eyes, mouth, pharynx, or intestine. It had no external organs for parasitic life (e.g. attachment organs) and inhabited the haemocoel of the host. When mature, it emerged from the host and secreted a silky substance around itself to form a cocoon. The cocoon contained egg capsules with 19–42 eggs. Larvae, hatched from the capsule, had a ciliated body and a pair of eye spots. They were negatively phototactic and capable of invading suitable hosts. These morphological and life history features suggest this parasitic worm may belong to the family Fecampiidae (Platyhelminthes: Turbellaria), one of a few obligate parasite taxa in Turbellaria. Molluscan hosts which are common for parasitic Platyhelminthes have not previously been known for this family. The newly discovered parasite may be important for understanding the evolution of parasitism in Platyhelminthes.

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.

On low intertidal and shallow subtidal shores on the west coast of Okinawa, Japan, we investigated the trophic associations of sacoglossan opisthobranchs associated with Bryopsidalean green algae. During 11 short research visits (55 days total) from 2002 to 2008, we recorded almost 500 specimens of 11 species. These sacoglossans include a new record for Japan (Caliphylla A. Costa, 1867), a recent record for Japan (Placida daguilarensis Jensen, 1990), two undescribed species (Placida Trinchese, 1876 and Elysia Risso, 1818), one unnamed (but welldescribed) species (Placida sp. sensu Baba 1986), and six other Indo-Pacifi c species. Not only did we record more sacoglossan species but also we found higher slug abundances than other colleagues in Okinawa or the Indo-Pacifi c region. Quantitative population attributes and feeding preferences are described for these sacoglossans. In contrast to temperate geographic regions, several of these Japanese sacoglossans specialized on a single algal genus rather than two or more genera in different families. This specifi city is consistent with narrower host-plant associations in high-diversity communities; yet monophagy has not yet been demonstrated in this guild of Okinawan sacoglossans. Given the broad geographic ranges, restricted host ranges, often predictable populations, and high frequency of life cycles with planktotrophic larvae, western Pacifi c subtropical sacoglossans should be considered “predictably rare” (sensu Rabinowitz 1981) rather than at “special risk” (sensu Clark 1994).

In December 2008, eight sacoglossan specimens of Hermaea Loven, 1844 were collected from uniseriate red algae (cf. Wrangelia tanegana) at two sites on the west coast of Okinawa, Japan. These specimens are compared to the described Aplysiopsis wrangeliae Ichikawa, 1993 from Okinawa which we and other authors have previously suggested belongs to the genus Hermaea; we suggest that our specimens are attributable to Hermaea wrangeliae (Ichikawa, 1993).

Marine specialist herbivores inhabiting Japanese rocky shores are significantly more diverse than in other biogeographical regions at comparable latitudes. The interaction webs of specialist sacoglossans were investigated on the Pacific shore of Honshu, Japan. The host use of the small stenophagous sacoglossan opisthobranch Placida sp. (sensu Baba, 1986) was investigated in association with the green macroalgae Codium spp. Based on field associations, Placida sp. attacked six congeneric algal host species out of eight investigated (75%) in and around Sagami Bay and ten of 20 species (50%) in Japan. In pairwise-choice feeding experiments, Placida sp. preferred the algal host from which it was collected (source alga) to alternate host and non-host algae. Preference rankings, however, could be altered based on the condition or identity of the choices (e.g. old versus young fronds of C. fragile). Connectance values were lower in these high-diversity assemblages than in their low-diversity counterparts on other temperate shores (but these values may increase with additional study). The sacoglossan occasionally coexisted with two other common sacoglossan species (Elysia trisinuata and E. setoensis) and several other less common ones. However, interspecific feeding interactions appeared minor, with no discernible evidence of interference or exploitation competition. Despite the diverse assemblage of specialist sacoglossans feeding on Codium spp., these Japanese sacoglossans (1) had low niche differentiation, (2) were weak interactors with their hosts, and (3) had negligible intra-guild interactions.

Two crawling medusae, Staurocladia oahuensis (Edmondson, 1930) and S. bilateralis (Edmondson, 1930) were found to be abundant in intertidal rock pools in Kominato from late summer until early winter. The two species were found to rarely share the same individual alga, and sometimes showed exclusive occupancy of pools at higher intertidal levels. The abundance of the two species of medusae fluctuated widely over time with both species showing similar population structures during their period of occurrence. The asexual reproduction of the medusae was considered to be a cause of the distributional pattern and the fluctuation in abundance. An experiment was conducted to evaluate the rate of asexual reproduction under different conditions. At 12°C neither species performed asexual reproduction, while at 17°C and higher temperatures both species reproduced asexually at a high rate. The number of each population was found to nearly double in about a week. The coexistence of the two species of medusae in tidepools is discussed in relation to the habitat characteristics. S. oahuensis and S. bilateralis were not known previously from Japan; this constitutes a new record of both species from Japanese waters. We also found both species in several other warm water locations in Japan.

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 opsin from the John Dory Zeus faber rod visual pigment (maximum spectral sensitivity =492 nm) was cloned and sequenced. Comparison of the John Dory rod opsin sequence with those from other fish with blue-shifted scotopic spectral sensitivity provides further evidence for the spectral tuning of this group of visual pigments.

The rod opsin sequences from Gambusia affinis holbrooki and Poecilia reticulata were cloned and sequenced. The opsin sequences were found to be 96middot;8% identical, reflecting the similarity of the rod visual pigment absorbances in these two Poeciliid fish.

The preys of three flabellinid nudibranchs and the distribution of their pediveliger larvae were investigated to reveal the relation between the width of dietary spectrum and the larval recruitment site. Hundreds of pediveligers were found in total from the field. Flabellina amabilis and Flabellina sp. were specialists consuming exclusively one hydroid species, while Flabellina athadona was a generalist eating five hydroid species. Not only in the specialists but in the generalist, the pediveligers were associated with their adult diet hydroids, although there was a hydroid species on which the larvae of the generalist could hardly succeed to settle. As to microdistribution of pediveligers on the hydroids, there was a significant difference between the specialists and the generalist; pediveligers of F. amabilis and F. sp. were mostly found to directly adhere to the naked hydranths, while those of F. athadona were found away from the naked hydranths. The causes of these phenomena are 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.

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.

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.

Transglutaminase 1 (TG1) is an enzyme that is expressed and activated during terminal differentiation of keratinocytes and synthesizes cornified envelope by a cross-linking reaction. The gene encoding human TG1 was isolated from human genomic DNA and characterized. It spans 14.3 kilobase pairs and is composed of 15 exons. All exon-intron junctional sequences conformed to the canonical GT-AG rule. The translation start was located in the second exon. The active site Cys residue of the enzyme was in exon 7. The coding sequence for human TG1 was comprised of 2454 nucleotides identical with the published human TG1-cDNA sequence (Yamanishi, K., Liew, F.-M., Konishi, K., Yasuno, H., Doi, H., Hirano, J., and Fukushima, S. (1991) Biochem. Biophys. Res. Commun. 175, 906-913). The sizes of exons from 3 to 14 were markedly conserved between the genes for the human TG1 and factor XIIIa, another member of the transglutaminase family. The one major and two minor transcription initiation sites of the TG1 gene were determined by primer extension. The 5'-flanking region of the human TG1 gene showed features of a housekeeping gene and contained potential regulatory motifs, including elements found in keratinocyte-related genes. The chromosome sublocalization of the TG1 gene was assigned to 14q11.2.

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.