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The article discusses a study conducted to clarify whether flagellate-like cells found in histological preparations of the tunic of diseased Halocynthia roretzi (Drasche) were the causative agent of soft tunic syndrome in the ascidian. The flagellate was cultured from the softened tunic in vitro and confirmed that the tunics of healthy ascidians softened 17 days after exposure including the final 12 days in aerated, running sea water. The study concluded that the flagellate is the causative agent of soft tunic syndrome.

This article discusses a study which examined photosymbiotic ascidians from Kenting and Lyudao in Taiwan. The study surveyed the photosymbiotic ascidian fauna in Keelung, Kenting, and Lyudao. It recorded nine species in total from Kenting and Lyudao but it found no photosymbiotic species in Keelung. It suggested that there is no species recorded in Keelung because of the cold surface water in winter in the region. In addition, the study showed some differences and the diversity of the microhabitats.

Trididemnum clinides is a multi-photosymbiotic ascidian that inhabits shallow coral reef lagoons. Three types of cyanobacteria are harboured in the tunic of the ascidian colony; of these, two are unicellular coccoid cyanobacteria and the other is a multicellular filamentous type. They also differ in ultrastructure and distribution patterns within the host tunic. Microspectrophotometric analysis revealed the composition of photosynthetic pigments in each photosymbiont. One of the coccoid types is yellowish-green and is distributed under the colony surface. This photosymbiont cell preferentially absorbs red and blue light, and therefore the dominant colour in the inner tunic is green. The other two types of coexisting photosymbionts contain the green-light-absorbing R-phycoerythrin as the major photosynthetic pigment; they exploit the wavelengths of light not used by the first type of photosymbiont. In T. clinides, the outer and inner photosymbionts in the tunic have different photosynthetic pigments, which adapt to each microhabitat, thereby sharing the incident light resources effectively. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the diet of a notodelphyid species inhabiting in the colonial ascidian, Diplosoma virens. Materials and methods; Results and discussion.

While nanoscale nipple arrays are expected to reduce light reflection and/or dust contamination in some insects, similar structures have been reported in various marine invertebrates. To evaluate the anti-contamination property of the structure in aquatic regimes, we measured the adsorption and adhesion forces on the flat surface and MOSMITE™ (Mitsubishi Chemical Corporation, Tokyo, Japan), a synthetic material mimicking the nipple array, under water. A small force toward the surface occurred when the probe approached the substrate surface. This adsorption force was significantly smaller on MOSMITE™ than on the flat surface. The adhesion force toward the surface occurred when the probe was detached from the surface, and it was also significantly smaller on MOSMITE™ than on the flat surface. The adhesion force in the air was much greater than the force under water, and the force was also significantly smaller on MOSMITE™ than on the flat surface. In the aquatic regime, the nipple array provides less adsorption/adhesion properties for the surface and thus, the organisms would have less contamination of microparticles on their body surface. As the adsorption and adhesion forces are also involved in the attachment of cells, tissue, and larvae, less adhesive body surfaces should be beneficial for survival in aquatic environments, as well as land environments. [ABSTRACT FROM AUTHOR]

Presents information on a study which compared the hemocyte behavior during allorejection reactions in two species of ascidians, Botryllus scalaris and Symplegma reptans. Methodology; Results and discussion.

Presents information on a study that deals with the tunic morphology and cellulosic components of thaliacean tunicates from the orders of Thaliacea. Diversity and evolution of the tunic in union with the phylogeny of tunicates; Materials and methods employed; Results and discussion of the study.

Examines the allogeneic rejection between colonies in two compound ascidians. Names of ascidians examined; Use of electron microscope in examination; What occurs when two incompatible colonies are brought into contact at their growing edges.

Investigates the morphology and functions of the tunic in the colonial ascidian Aplidium yamazii. Results of tunic rounding assay under experimental condition; Structure of the tunic cuticle.

SYNOPSIS. Sexual differentiation in malacostracan Crustacea is controlled by the androgenic gland hormone (AGH). In males, the primordial androgenic glands (AG) develop and AGH induces male morphogenesis. In females, the primordial AG does not develop and the ovaries differentiate spontaneously. Implantation of the AG into females yields various results, showing that the sensitivity to AGH differs with the species and the receptive organs. Purified AGH of the isopod consists of at least two molecular forms, which exist as monomeric proteins with molecular weights of 17,000 ± 800 and 18,300 ± 1,000 Da and with isoelectric points of about 4.5 and 4.3, respectively. The antiserum raised against purified AGH makes it possible to measure AGH activity by immunoassay. Neurohormones control male and female reproduction. In males, they are involved in the maintenance of the male germinative zone and the control of AG activity. In females, the secondary vitellogenesis is controlled by the vitellogenesis-inhibiting hormone (VIH) and the vitellogenesis- stimulating hormone (VSH). VIH isolated from the lobster is a peptide with a molecular weight of 9,135 Da and shows homology to the crustacean hyperglycemic hormone and moltinhibiting hormone. Involvement of the molting hormone and the juvenile hormone-like compound in the secondary vitellogenesis have also been suggested. In the amphipod , the vitellogenesis- stimulating ovarian hormone (VSOH) seems to control vitellogenin synthesis [ABSTRACT FROM PUBLISHER]

Ascidians are marine sessile chordates that comprise one of the major benthic animal groups in marine ecosystems. They sometimes cause biofouling problems on artificial structures underwater, and non-indigenous, invasive ascidian species can potentially and seriously alter native faunal communities. Ascidian larvae are usually tadpole-shaped, negatively phototactic, and adhere on substrates by secreting a glue from their adhesive organs. Although larvae often prefer hydrophobic surfaces, such as a silicone rubber, for settlement, hydrophobic materials are often used to reduce occurrence of fouling organisms on artificial structures. This inconsistency may indicate that an attractive surface for larvae is not always suitable for settlement. Micro-scale structures or roughness may enhance the settlement of ascidian larvae, but settlement is significantly reduced by a nano-scale nipple array (or moth-eye structure), suggesting functional properties of similar structures found on the body surfaces of various invertebrates. The substrate preferences of larvae should be one of the important bases in considering measures against biofouling, and this review also discusses the potential uses of materials to safely reduce the impacts of invasive species. [ABSTRACT FROM AUTHOR]

Background: Invisibility in the water column is a crucial strategy for gelatinous zooplanktons in avoiding detection by visual predators, especially for animals distributed in the euphotic zone during the daytime; i.e., surface dwellers that do not undergo diel vertical migration. Salps, a member of the subphylum Tunicata (Urochordata), usually have a transparent body that is entirely covered with a cellulosic matrix, called the tunic. Some non-migrator species are known to exhibit a nano-scale nipple array on the tunic surface. However, the physical properties of the salp tunic has been poorly investigated, except for Thetys vagina, in which the tunic was expected to show low reflectance based on the refractive index of the tunic. Pegea confoederata is a non-vertical migrant salp showing pinkish-brown body. We measured the hardness, water content, absorption spectra, and refractive index of its tunic to evaluate its fragility and visibility. Results: There are nipple-like protuberances about 80 nm high on the surface of the tunic in P. confoederata. The tunic is very soft; the maximum force to pierce the tunic with a steel rod (1 mm diameter) was < 1 N. The water content of the tunic was > 95%. The absorption spectra of the tunic had no prominent peaks in the wavelength range of 280–800 nm, indicating the tunic is nearly transparent. The difference in refractive indices between tunic and seawater was estimated as 0.002–0.015 at 589 nm. Rigorous coupled wave analyses (RCWA) of light reflection based on 3-dimensional models supported an anti-reflective effect of the nipple array on the tunic surface, which was estimated to vary slightly depending on the forms and the arrangement patterns of nipple-like protuberances in an array. Conclusions: The tunic of P. confoederata is very soft and contains more water than those of sessile tunicates (ascidians). Based on the refractive index of the tunic, light reflection is expected to be very low, making this salp's tunic barely visible in water column. Our results suggest that the nipple array may produce an anti-reflective effect. [ABSTRACT FROM AUTHOR]

Ascidians are known to harbour bacterial symbionts in their tunics. In particular, the ascidian genus Lissoclinum can host abundant and diverse cyanobacterial associates. Here, we determined the diversity and host-specificity of cyanobacteria inhabiting 28 ascidian samples corresponding to eight Lissoclinum species: L. bistratum, L. midui, L. patella, L. punctatum, and L. timorense from Japan, L. aff. fragile and L. verrilli from the Bahamas, and L. perforatum from Spain and Chile. Cyanobacterial symbionts were characterized using both partial 16S rRNA gene sequences and sequences obtained for the entire 16S-23S rRNA internal transcribed spacer region (ITS). We found that both host species and geographic location played a role in structuring ascidian-cyanobacterial symbioses. Broad biogeographic trends included the dominance of Prochloron symbionts in Japanese ascidians and the presence of a novel cyanobacterial lineage in L. aff. fragile hosts from the Bahamas. Within each geographic region, a high degree of host-specificity was observed, where similar symbionts were recovered from ascidian hosts across multiple collection locations. Further, our analysis revealed the existence of nine distinct Prochloron clades in Japan, some of which corresponded to particular host species and sampling sites. For L. aff. fragile, further differences were observed between cyanobacterial symbionts in ascidians from reef and mangrove habitats. Our results showed high host-specificity in ascidian-cyanobacterial symbioses characterized by cryptic diversity and structured by host identity, location and habitat. [ABSTRACT FROM AUTHOR]

Echinoderes komatsui (Kinorhyncha: Cyclorhagida) is a meiobenthic animal inhabiting the interstitial spaces of the sediment on a subtropical tidal flat along the Oura River, Japan. This species mostly occurred within 0-10 mm from the surface of the sediment, and the dispersion pattern was significantly patchy. The population dynamics of E. komatsui were investigated by monthly surveys from January 2014 to May 2016 at four sites along the river, and from April 2015 to May 2016 at one site in the mangrove forest. Echinoderes komatsui occurred all year round; however, the population density showed different patterns among the sampling sites in response to seasonal changes. On the tidal flat, the population density was high in winter, but very low in summer. In the mangrove forest, the density was high (or not low) throughout the year. As was shown in laboratory experiments, E. komatsui survived in 1-44 salinity seawater but died at 0 (salinity experiments), and died within 4.5 days at 40°C (temperature experiments). Therefore, the low population density recorded in summer on the tidal flat was likely caused by high temperature and fresh water. The shade offered by the mangrove forest suppressed the increase in temperature of the sediment in the summer, probably resulting in the higher population density at this site relative to the tidal flat population. Mangrove forests may also mitigate the disturbance of the sediment by summer typhoons and serve as stable environments that are fundamental in the sustainability of estuarine meiobenthic fauna. [ABSTRACT FROM AUTHOR]

The article focuses on the disappearance and domination of the black sponge in southern Japan. It references the study conducted in Tokunoshima and Okinoerabu to determine the status of Terpios hoshinota patches. It states that a new massive outbreak at Yakomo, Okinoerabu was not considered as an irreversible climax for the affected reefs. It adds that the species can persist after its initial outbreak once it enters a reef.

The infection of the kinetoplastid flagellate Azumiobodo hoyamushi causes soft tunic syndrome that often results in mass mortality in the aquaculture of the edible ascidian Halocynthia roretzi. In the diseased ascidian individuals, the flagellates are exclusively found in the tunic matrix that entirely cover the epidermis, and never invade into internal tissues, such as a mantle. The present study for the first time demonstrated that the ascidian blood plasma and hemolymph have an activity to agglutinate and disintegrate the flagellates, suggesting the innate immunity protects the internal tissue from the invasion of A. hoyamushi. This activity is indifferent between the healthy and the diseased individuals. Allo-specific recognition and cytotoxic reaction among ascidian hemocytes, so-called contact reaction, occur among the individuals of healthy–healthy, healthy–diseased, and diseased–diseased combination, and therefore, the hemocytes from diseased individuals still retain the allo-reactivity. Moreover, the allo-reactive combinations are not changed under the presence of the flagellates, indicating the flagellates neither suppress nor induce the effector system of the contact reaction. These results suggest that the infection of A. hoyamushi does not impair the innate immunity in the ascidian hemolymph. • Azumiobodo hoyamushi was incubated with hemolymph or blood plasma of Halocynthia roretzi. • A. hoyamushi was agglutinated and disintegrated both by hemolymph and blood plasma. • Innate immunity of H. roretzi protects internal tissues from invasion of A. hoyamushi. [ABSTRACT FROM AUTHOR]

Abstract: The marine cyanobacterium Prochloron is a unique photosynthetic organism that lives in obligate symbiosis with colonial ascidians. We compared Prochloron harbored in four different host species and cultured Prochlorothrix by means of spectroscopic measurements, including time-resolved fluorescence, to investigate host-induced differences in light-harvesting strategies between the cyanobacteria. The light-harvesting efficiency of photosystems including antenna Pcb, PS II–PS I connection, and pigment status, especially that of PS I Red Chls, were different among the four samples. We also discuss relationships between these observed characteristics and the light conditions, to which Prochloron cells are exposed, influenced by distribution pattern in the host colonies, presence or absence of tunic spicules, and microenvironments within the ascidians'' habitat. [Copyright &y& Elsevier]

The spawning behavior and early embryogenesis of Palythoa tuberculosa (Anthozoa, Zoantharia) were observed in August 2009 off Okinawa Island, Japan. P. tuberculosa released zygotes just after high tide around new moon nights. The mean diameter of zygotes was 365.6 ± s.d.14.8 μm, and zygotes did not contain any symbiotic algae (zooxanthellae). About 2 h after spawning, the first cleavage furrow appeared on one side of the zygotes, although it was uncertain when eggs were fertilized. After second cleavage, the arrangement of blastomeres was pseudospherical. At 9 h after spawning, the embryo became a concave-convex dish shape, then gastrulation occurred and the blastopore was formed. Seven-day old larvae were ellipsoid and about 700 μm long, with an open mouth at one end. Two weeks after spawning, the larvae developed a longitudinal band of long cilia (= ventral ciliate band)that is characteristic of zoanthella larvae. In P. tuberculosa, larvae show a non-radial body plan and then metamorphose to almost-radial (in outward appearance) polyps after settlement. These results may support a hypothesis that a common ancestor of Cnidaria had a bilateral body plan that has been secondarily lost in some extant cnidarians. [ABSTRACT FROM AUTHOR]

Monthly samplings of solitary entoprocts were carried out at Mizugama and Ginowan Fishery Port, Okinawa Island, the central Ryukyus, Japan from November 2000 to November 2001. We examined the entoproct populations on the glass slides that had been placed at the two sites for 2 months, and a total of 18,322 individuals of solitary entoprocts were recorded. They were Loxomitra mizugamaensis, L. ryukyuensis, L. tetraorganon, Loxosomella aloxiata, L. intragemmata, L. lecythifera, L. monocera, L. stomatophora, and Loxocorone allax. Our analyses indicate that (1) the abundance of solitary entoprocts in this region is high in summer and low in winter, (2) most species reproduce by budding all year round, and (3) sexual reproduction is restricted to a short period in summer (July or August). [ABSTRACT FROM AUTHOR]

Summary: Terpios hoshinota is an aggressive, space‐competing sponge that kills various stony corals. Outbreaks of this species have led to intense damage to coral reefs in many locations. Here, the first large‐scale 16S rRNA gene survey across three oceans revealed that bacteria related to the taxa Prochloron, Endozoicomonas, SAR116, Ruegeria, and unclassified Proteobacteria were prevalent in T. hoshinota. A Prochloron‐related bacterium was the most dominant and prevalent cyanobacterium in T. hoshinota. The complete genome of this uncultivated cyanobacterium and pigment analysis demonstrated that it has phycobiliproteins and lacks chlorophyll b, which is inconsistent with the definition of Prochloron. Furthermore, the cyanobacterium was phylogenetically distinct from Prochloron, strongly suggesting that it should be a sister taxon to Prochloron. Therefore, we proposed this symbiotic cyanobacterium as a novel species under the new genus Candidatus Paraprochloron terpiosi. Comparative genomic analyses revealed that 'Paraprochloron' and Prochloron exhibit distinct genomic features and DNA replication machinery. We also characterized the metabolic potentials of 'Paraprochloron terpiosi' in carbon and nitrogen cycling and propose a model for interactions between it and T. hoshinota. This study builds a foundation for the study of the T. hoshinota microbiome and paves the way for better understanding of ecosystems involving this coral‐killing sponge. [ABSTRACT FROM AUTHOR]

The ciliate Miamiensis avidus causes scuticociliatosis in Japanese flounder Paralichthys olivaceus . We previously reported three serotypes of this ciliate distinguishable by serotype-specific antigenic polypeptides (serotype I, 30 kDa; serotype II, 38 kDa; serotype III, 34 kDa). In this study, we determined the localization site of the serotype-specific polypeptides in the ciliate and determined the genes encoding the polypeptides, using the isolates IyoI (serotype I), Nakajima (serotype II), and Mie0301 (serotype III). SDS-PAGE and immunoblot analysis of cilia, membrane proteins, and cytoskeletal elements of the ciliates revealed that the polypeptides were abundant in the former two. Scanning electron microscopy of ciliates immobilized by homologous antiserum showed morphological changes in the cilia. These evidences suggested that the polypeptides were ciliary membrane immobilization antigens. The ciliary genes identified showed low identity scores—< 51.5% between serotypes. To differentiate the serotypes, we designed serotype-specific PCR primer sets based on the DNA sequences. The PCR-based serotyping results were completely consistent with conventional serotyping methods (immobilization assay and immunoblot analysis). Twenty of 21 isolates were classified as either serotype I or II, and one isolate was undistinguishable. The combination of species-specific PCR previously reported and three serotype-specific PCR could be useful for identifying, serotyping, and surveillance for occurrences of new serotypes of M. avidus . [ABSTRACT FROM AUTHOR]

Ascidians (Chordata, Tunicata) are an important group for the study of invasive species biology due to rapid generation times, potential for biofouling, and role as filter feeders in an ecosystem. Phallusia nigra is a putative cosmopolitan ascidian that has been described as introduced or invasive in a number of regions in the Indo-Pacific Ocean (India, Japan, and Hawaii) and in the Mediterranean. The taxonomic description of P. nigra includes a striking smooth, black tunic and large size. However, there are at least two similar Phallusia species--P. philippinensis and P. fumigata--which also have dark black tunics and can be difficult to discern from P. nigra. The distribution of P. nigra broadly overlaps with P. philippinensis in the Indo-Pacific and P. fumigata in the Mediterranean. A morphological comparison of P. nigra from Japan, the Caribbean coast of Panama, and Brazil found that Atlantic and Pacific samples were different species and led us to investigate the range of P. nigra using morphological and molecular analyses. We sequenced 18S rDNA and cytochrome oxidase B of individual ascidians from the Red Sea, Greece, Singapore, Japan, Caribbean Panama, Florida, and Brazil. Our results show that identification of the disparate darkly pigmented species has been difficult, and that several reports of P. nigra are likely either P. fumigata or P. philippinensis. Here we include detailed taxonomic descriptions of the distinguishing features of these three species and sequences for molecular barcoding in an effort to have ranges and potential invasions corrected in the ascidian literature. [ABSTRACT FROM AUTHOR]

Secondary metabolites are ubiquitous in bacteria, but by definition, they are thought to be nonessential. Highly toxic secondary metabolites such as patellazoles have been isolated from marine tunicates, where their exceptional potency and abundance implies a role in chemical defense, but their biological source is unknown. Here, we describe the association of the tunicate Lissoclinum patella with a symbiotic a-proteobacterium, Candidatus Endolissoclinum faulkneri, and present chemical and biological evidence that the bacterium synthesizes patellazoles. We sequenced and assembled the complete Ca. E. faulkneri genome, directly from metagenomic DNA obtained from the tunicate, where it accounted for 0.6% of sequence data. We show that the large patellazoles biosynthetic pathway is maintained, whereas the remainder of the genome is undergoing extensive streamlining to eliminate unneeded genes. The preservation of this pathway in streamlined bacteria demonstrates that secondary metabolism is an essential component of the symbiotic interaction. [ABSTRACT FROM AUTHOR]

Among all photosynthetic and non-photosynthetic prokaryotes, only cyanobacterial species belonging to the genera Acaryochloris and Prochlorococcus have been reported to synthesize α-carotene. We reviewed the carotenoids, including their chirality, in unusual cyanobacteria containing diverse Chls. Predominantly Chl d-containing Acaryochloris (two strains) and divinyl-Chl a and divinyl-Chl b-containing Prochlorococcus (three strains) contained β-carotene and zeaxanthin as well as α-carotene, whereas Chl b-containing Prochlorothrix (one strain) and Prochloron (three isolates) contained only β-carotene and zeaxanthin but no α-carotene as in other cyanobacteria. Thus, the capability to synthesize α-carotene seemed to have been acquired only by Acaryochloris and Prochlorococcus. In addition, we unexpectedly found that α-carotene in both cyanobacteria had the opposite chirality at C-6′: (6′S)-chirality in Acaryochloris and normal (6′R)-chirality in Prochlorococcus, as reported in some green algae and land plants. The results represent the first evidence for the natural occurrence and biosynthesis of (6′S)-α-carotene. All the zeaxanthins in these species were of the usual (3R,3′R)-chirality. Therefore, based on the identification of the carotenoids and genome sequence data, we propose a biosynthetic pathway for the carotenoids, particularly α-carotene, including the participating genes and enzymes. [ABSTRACT FROM AUTHOR]

The life cycle of the fish ectoparasitic isopod Gnathia trimaculata is described based on both field samplings and laboratory observations. Species identification of the larvae was based on morphological observation and supported by molecular analysis. As the results of field samplings in several sites of southwestern and central Japan (24-34°N, 124-139°E) from 2005-2011, approximately 900 third-stage larvae of G. trimaculata were found on 25 elasmobranch species, and 220 first- and second-stage larvae were found on three teleost species. No third-stage larvae were found on the teleosts, and the larvae of younger stages never infested elasmobranchs. Therefore, G. trimaculata is supposed to shift its host from teleosts to elasmobranchs as it develops. We discuss the developmental periods, life span, distribution, and predation risk of the present species compared with other gnathiid species. [ABSTRACT FROM AUTHOR]

The native form of cellulose is a fibrillar composite of two crystalline phases, the triclinic I and monoclinic I allomorphs. Allomorph ratios are species-specific, and this gives rise to natural structural variations in cellulose crystals. However, the mechanisms contributing to crystal formation remain unknown. We show that the two crystalline phases of cellulose are tailored to distinct structures during different developmental stages of the tunicate chordate Oikopleura dioica. Larval cellulose consisting of I allomorph constitutes the body cuticle fin, whereas adult cellulose consisting of I allomorph frames a mucous filter-feeding device, the 'house.' Both structures are secreted from the epidermis in accordance with the mutually exclusive expression patterns of two distinct putative cellulose synthase genes. We discuss a possible linkage between structural variations of the crystalline phases of cellulose and the underlying evolutionary genetics of cellulose biosynthesis. [ABSTRACT FROM AUTHOR]

Abstract: The complete nucleotide sequences of the mitochondrial (mt) genomes of the entoprocts Loxocorone allax and Loxosomella aloxiata were determined. Both species carry the typical gene set of metazoan mt genomes and have similar organizations of their mt genes. However, they show differences in the positions of two tRNALeu genes. Additionally, the tRNAVal gene, and half of the long non-coding region, is duplicated and inverted in the Loxos. aloxiata mt genome. The initiation codon of the Loxos. aloxiata cytochrome oxidase subunit I gene is expected to be ACG rather than AUG. The mt gene organizations in these two entoproct species most closely resemble those of mollusks such as Katharina tunicata and Octopus vulgaris, which have the most evolutionarily conserved mt gene organization reported to date in mollusks. Analyses of the mt gene organization in the lophotrochozoan phyla (Annelida, Brachiopoda, Echiura, Entoprocta, Mollusca, Nemertea, and Phoronida) suggested a close phylogenetic relationship between Brachiopoda, Annelida, and Echiura. However, Phoronida was excluded from this grouping. Molecular phylogenetic analyses based on the sequences of mt protein-coding genes suggested a possible close relationship between Entoprocta and Phoronida, and a close relationship among Brachiopoda, Annelida, and Echiura. [Copyright &y& Elsevier]