Time course for tail regression during metamorphosis of the ascidian Ciona intestinalis.

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Matsunobu, Shohei; Sasakura, Yasunori

2015-09-01

In most ascidians, the tadpole-like swimming larvae dramatically change their body-plans during metamorphosis and develop into sessile adults. The mechanisms of ascidian metamorphosis have been researched and debated for many years. Until now information on the detailed time course of the initiation and completion of each metamorphic event has not been described. One dramatic and important event in ascidian metamorphosis is tail regression, in which ascidian larvae lose their tails to adjust themselves to sessile life. In the present study, we measured the time associated with tail regression in the ascidian Ciona intestinalis. Larvae are thought to acquire competency for each metamorphic event in certain developmental periods. We show that the timing with which the competence for tail regression is acquired is determined by the time since hatching, and this timing is not affected by the timing of post-hatching events such as adhesion. Because larvae need to adhere to substrates with their papillae to induce tail regression, we measured the duration for which larvae need to remain adhered in order to initiate tail regression and the time needed for the tail to regress. Larvae acquire the ability to adhere to substrates before they acquire tail regression competence. We found that when larvae adhered before they acquired tail regression competence, they were able to remember the experience of adhesion until they acquired the ability to undergo tail regression. The time course of the events associated with tail regression provides a valuable reference, upon which the cellular and molecular mechanisms of ascidian metamorphosis can be elucidated. Copyright © 2015 Elsevier Inc. All rights reserved.

Sessile macro-epibiotic community of solitary ascidians, ecosystem engineers in soft substrates of Potter Cove, Antarctica

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Clara Rimondino

2015-01-01

Full Text Available The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo, South Shetlands, Antarctica, show a high density and richness of macrobenthic species, particularly ascidians. In other areas, ascidians have been reported to play the role of ecosystem engineers, as they support a significant number of epibionts, increasing benthic diversity. In this study, a total of 21 sessile macro-epibiotic taxa present on the ascidian species Corella antarctica Sluiter, 1905, Cnemidocarpa verrucosa (Lesson, 1830 and Molgula pedunculata Herdman, 1881 were identified, with Bryozoa being the most diverse. There were differences between the three ascidian species in terms of richness, percent cover and diversity of sessile macro-epibionts. The morphological characteristics of the tunic surface, the available area for colonization (and its relation with the age of the basibiont individuals and the pH of the ascidian tunic seem to explain the observed differences. Recent environmental changes in the study area (increase of suspended particulate matter caused by glaciers retreat have been related to observed shifts in the benthic community structure, negatively affecting the abundance and distribution of the studied ascidian species. Considering the diversity of sessile macro-epibionts found on these species, the impact of environmental shifts may be greater than that estimated so far.

Genetic pathways for differentiation of the peripheral nervous system in ascidians

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Waki, Kana; Imai, Kaoru S.; Satou, Yutaka

2015-01-01

Ascidians belong to tunicates, the sister group of vertebrates. Peripheral nervous systems (PNSs) including epidermal sensory neurons (ESNs) in the trunk and dorsal tail regions of ascidian larvae are derived from cells adjacent to the neural plate, as in vertebrates. On the other hand, peripheral ESNs in the ventral tail region are derived from the ventral ectoderm under the control of BMP signalling, reminiscent of sensory neurons of amphioxus and protostomes. In this study, we show that two distinct mechanisms activate a common gene circuit consisting of Msx, Ascl.b, Tox, Delta.b and Pou4 in the dorsal and ventral regions to differentiate ESNs. Our results suggest that ventral ESNs of the ascidian larva are not directly homologous to vertebrate PNSs. The dorsal ESNs might have arisen via co-option of the original PNS gene circuit to the neural plate border in an ancestral chordate. PMID:26515371

Sessile macro-epibiotic community of solitary ascidians, ecosystem engineers in soft substrates of Potter Cove, Antarctica

OpenAIRE

Rimondino, Clara; Torre, Luciana; Sahade, Ricardo Jose; Tatian, Marcos

2016-01-01

The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo), South Shetlands, Antarctica, show a high density and richness of macrobenthic species, particularly ascidians. In other areas, ascidians have been reported to play the role of ecosystem engineers, as they support a significant number of epibionts, increasing benthic diversity. In this study, a total of 21 sessile macro-epibiotic taxa present on the ascidian species Corella antarctica Sluiter, 1905, Cnemidocarpa verr...

Diversity of pufM genes, involved in aerobic anoxygenic photosynthesis, in the bacterial communities associated with colonial ascidians.

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Martínez-García, Manuel; Díaz-Valdés, Marta; Antón, Josefa

2010-03-01

Ascidians are invertebrate filter feeders widely distributed in benthic marine environments. A total of 14 different ascidian species were collected from the Western Mediterranean and their bacterial communities were analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene. Results showed that ascidian tissues harbored Bacteria belonging to Gamma- and Alphaproteobacteria classes, some of them phylogenetically related to known aerobic anoxygenic phototrophs (AAPs), such as Roseobacter sp. In addition, hierarchical cluster analysis of DGGE patterns showed a large variability in the bacterial diversity among the different ascidians analyzed, which indicates that they would harbor different bacterial communities. Furthermore, pufM genes, involved in aerobic anoxygenic photosynthesis in marine and freshwater systems, were widely detected within the ascidians analyzed, because nine out of 14 species had pufM genes inside their tissues. The pufM gene was only detected in those specimens that inhabited shallow waters (<77 m of depth). Most pufM gene sequences were very closely related to that of uncultured marine bacteria. Thus, our results suggest that the association of ascidians with bacteria related to AAPs could be a general phenomenon and that ascidian-associated microbiota could use the light that penetrates through the tunic tissue as an energy source.

Monitoring the magnitude of marine vessel infestation by non-indigenous ascidians in the Mediterranean.

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Gewing, Mey-Tal; Shenkar, Noa

2017-08-15

Invasive ascidians (Chordata, Tunicata) are dominant nuisance organisms. The current study investigated the role of marine vessels in their dispersal and introduction. An examination of 45 dry-docked marine vessels, comprising recreational, commercial, and military craft, in five Israeli shipyards along the Mediterranean coast, revealed non-indigenous ascidians (NIA) on every second vessel investigated. Military vessels featured the highest ascidian abundance and richness, potentially related to their maintenance routine. Niche areas on the vessels such as sea chests and the propeller exhibited the highest occurrence of ascidians. Overall, these findings provide strong evidence that marine vessels play an acute role in NIA introduction and dispersal, with military vessels and niche areas on all the vessels being more susceptible to serving as vectors. A discovery of a new introduced species during the surveys suggests that the monitoring of marine vessels can serve as an effective tool for the early detection of NIA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stochastic model of cell rearrangements in convergent extension of ascidian notochord

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Lubkin, Sharon; Backes, Tracy; Latterman, Russell; Small, Stephen

2007-03-01

We present a discrete stochastic cell based model of convergent extension of the ascidian notochord. Our work derives from research that clarifies the coupling of invagination and convergent extension in ascidian notochord morphogenesis (Odell and Munro, 2002). We have tested the roles of cell-cell adhesion, cell-extracellular matrix adhesion, random motion, and extension of individual cells, as well as the presence or absence of various tissue types, and determined which factors are necessary and/or sufficient for convergent extension.

Phylogenetic study of the oxytocin-like immunoreactive system in invertebrates.

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Mizuno, J; Takeda, N

1988-01-01

1. A phylogenetic study of oxytocin (OXT)-like immunoreactive cells was performed by the PAP method in the central nervous system of invertebrates. 2. The immunoreactivity was detected in the nerve cells of Hydra magnipapillata of the Coelenterata; Neanthes japonica and Pheretima communissima of the Annelida; Oncidium verrucosum, Limax marginatus and Meretrix lamarckii of the Mollusca; and Baratha brassica of the Arthropoda. 3. No immunoreactive cells were found in Bipalium sp. of the Platyhelminthes; Pomacea canaliculata, Aplysia kurodai, Bradybaena similaris and Achatina fulica of the Mollusca; and Gnorimosphaeroma rayi, Procambarus clarkii, Hemigrapsus sanguineus, Helice tridens and Gryllus bimaculatus of the Arthropoda; Asterina pectinifera of the Echinodermata; and Halocynthia roretzi of the Protochordata. 4. These results demonstrate that an OXT-immunoreactive substance is widely present not only in vertebrates but also in invertebrates. 5. OXT seems to have been introduced into these invertebrates at an early stage of their phylogenetic history.

Phylogenetic study of the arginine-vasotocin/arginine-vasopressin-like immunoreactive system in invertebrates.

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Mizuno, J; Takeda, N

1988-01-01

1. A phylogenetic study of arg-vasotocin (AVT)/arg-vasopressin (AVP)-like immunoreactive cells was performed by the PAP method in the central nervous system of invertebrates. 2. The immunoreactivity was detected in the nerve cells of Hydra magnipapillata of the Coelenterata; Neanthes japonica and Pheretima communissima of the Annelida; Pomacea canaliculata, Aplysia kurodai, Oncidium verrucosum, Bradybaena similaris, Achatina fulica, Limax marginatus and Meretrix lamarckii of the Mollusca; Gnorimosphaeroma rayi, Hemigrapsus sanguineus, Gryllus bimaculatus and Baratha brassicae of the Arthropoda; Asterina pectinifera of the Echinodermata; and Halocynthia roretzi of the Protochordata. 3. No immunoreactivity was detected in Bipalium sp. of the Platyhelminthes, or in Procambarus clarkii and Helice tridens of the Arthropoda. 4. From these results, it appears that AVT/AVP is a phylogenetically ancient peptide which is present in a wide variety of invertebrates. 5. The actions of AVT/AVP and its presence in invertebrates are discussed.

Muscle differentiation in a colonial ascidian: organisation, gene expression and evolutionary considerations

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Burighel Paolo

2009-09-01

Full Text Available Abstract Background Ascidians are tunicates, the taxon recently proposed as sister group to the vertebrates. They possess a chordate-like swimming larva, which metamorphoses into a sessile adult. Several ascidian species form colonies of clonal individuals by asexual reproduction. During their life cycle, ascidians present three muscle types: striated in larval tail, striated in the heart, and unstriated in the adult body-wall. Results In the colonial ascidian Botryllus schlosseri, we investigated organisation, differentiation and gene expression of muscle beginning from early buds to adults and during zooid regression. We characterised transcripts for troponin T (BsTnT-c, adult muscle-type (BsMA2 and cytoplasmic-type (BsCA1 actins, followed by in situ hybridisation (ISH on sections to establish the spatio-temporal expression of BsTnT-c and BsMA2 during asexual reproduction and in the larva. Moreover, we characterised actin genomic sequences, which by comparison with other metazoans revealed conserved intron patterns. Conclusion Integration of data from ISH, phalloidin staining and TEM allowed us to follow the phases of differentiation of the three muscle kinds, which differ in expression pattern of the two transcripts. Moreover, phylogenetic analyses provided evidence for the close relationship between tunicate and vertebrate muscle genes. The characteristics and plasticity of muscles in tunicates are discussed.

Microenvironment and phylogenetic diversity of Prochloron inhabiting the surface of crustose didemnid ascidians.

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Nielsen, Daniel A; Pernice, Mathieu; Schliep, Martin; Sablok, Gaurav; Jeffries, Thomas C; Kühl, Michael; Wangpraseurt, Daniel; Ralph, Peter J; Larkum, Anthony W D

2015-10-01

The cyanobacterium Prochloron didemni is primarily found in symbiotic relationships with various marine hosts such as ascidians and sponges. Prochloron remains to be successfully cultivated outside of its host, which reflects a lack of knowledge of its unique ecophysiological requirements. We investigated the microenvironment and diversity of Prochloron inhabiting the upper, exposed surface of didemnid ascidians, providing the first insights into this microhabitat. The pH and O2 concentration in this Prochloron biofilm changes dynamically with irradiance, where photosynthetic activity measurements showed low light adaptation (Ek ∼ 80 ± 7 μmol photons m(-2) s(-1)) but high light tolerance. Surface Prochloron cells exhibited a different fine structure to Prochloron cells from cloacal cavities in other ascidians, the principle difference being a central area of many vacuoles dissected by single thylakoids in the surface Prochloron. Cyanobacterial 16S rDNA pyro-sequencing of the biofilm community on four ascidians resulted in 433 operational taxonomic units (OTUs) where on average -85% (65-99%) of all sequence reads, represented by 136 OTUs, were identified as Prochloron via blast search. All of the major Prochloron-OTUs clustered into independent, highly supported phylotypes separate from sequences reported for internal Prochloron, suggesting a hitherto unexplored genetic variability among Prochloron colonizing the outer surface of didemnids. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Nonreproductive role of gonadotropin-releasing hormone in the control of ascidian metamorphosis.

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Kamiya, Chisato; Ohta, Naoyuki; Ogura, Yosuke; Yoshida, Keita; Horie, Takeo; Kusakabe, Takehiro G; Satake, Honoo; Sasakura, Yasunori

2014-12-01

Gonadotropin-releasing hormones (GnRHs) are neuropeptides that play central roles in the reproduction of vertebrates. In the ascidian Ciona intestinalis, GnRHs and their receptors are expressed in the nervous systems at the larval stage, when animals are not yet capable of reproduction, suggesting that the hormones have non-reproductive roles. We showed that GnRHs in Ciona are involved in the animal's metamorphosis by regulating tail absorption and adult organ growth. Absorption of the larval tail and growth of the adult organs are two major events in the metamorphosis of ascidians. When larvae were treated with GnRHs, they completed tail absorption more frequently than control larvae. cAMP was suggested to be a second messenger for the induction of tail absorption by GnRHs. tGnRH-3 and tGnRH-5 (the "t" indicates "tunicate") inhibited the growth of adult organs by arresting cell cycle progression in parallel with the promotion of tail absorption. This study provides new insights into the molecular mechanisms of ascidian metamorphosis conducted by non-reproductive GnRHs. © 2014 Wiley Periodicals, Inc.

Modiolarca lateralis (Pteryomorphia: Mytilidae: bivalve associated to six species of ascidians from Bocas del Toro, Panama

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Juan I Cañete

2013-11-01

Full Text Available We describe the presence of the bivalve Modiolarca lateralis (Say, 1822 in six tropical ascidians Ascidia curvata, A. sydneiensis, A. panamensis, A. interrupta, Herdmania pallida and Polycarpa spongiabilis collected at depths of 1-3 m on coral reefs, mangrove roots and dock supports in Almirante Bay, Bocas del Toro, Panama (9°18'N, 82°13'W during June-July 2011. Bivalve prevalence varied between 9-30% across species, but was mainly associated with A. panamensis, P. spongiabilis and A. interrupta. Prevalence seems to be influenced by tunic thickness rather than by the ascidian size. Bivalves varied in size (0.6-11 mm shell length, with the smallest individual found in A. sydneiensis. There were only one or two bivalves per ascidians, although a maximum of 18 was found in one A. panamensis. M. lateralis seems to behave similarly to its temperate counterparts: it has a variety of hosts, occurs mainly in the anterior region of the ascidians, and has a variable abundance per host.

The influence of substrate material on ascidian larval settlement.

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Chase, Anna L; Dijkstra, Jennifer A; Harris, Larry G

2016-05-15

Submerged man-made structures present novel habitat for marine organisms and often host communities that differ from those on natural substrates. Although many factors are known to contribute to these differences, few studies have directly examined the influence of substrate material on organism settlement. We quantified larval substrate preferences of two species of ascidians, Ciona intestinalis (cryptogenic, formerly C. intestinalis type B) and Botrylloides violaceus (non-native), on commonly occurring natural (granite) and man-made (concrete, high-density polyethylene, PVC) marine materials in laboratory trials. Larvae exhibited species-specific settlement preferences, but generally settled more often than expected by chance on concrete and HDPE. Variation in settlement between materials may reflect preferences for rougher substrates, or may result from the influence of leached chemicals on ascidian settlement. These findings indicate that an experimental plate material can influence larval behavior and may help us understand how substrate features may contribute to differences in settlement in the field. Copyright © 2016 Elsevier Ltd. All rights reserved.

When shape matters: strategies of different Antarctic ascidians morphotypes to deal with sedimentation.

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Torre, Luciana; Abele, Doris; Lagger, Cristian; Momo, Fernando; Sahade, Ricardo

2014-08-01

Climate change leads to increased melting of tidewater glaciers in the Western Antarctic Peninsula region and sediment bearing glacial melt waters negatively affects filter feeding species as solitary ascidians. In previous work the erect-forms Molgula pedunculata and Cnemidocarpa verrucosa (Order Stolidobranchiata) appeared more sensitive than the flat form Ascidia challengeri (Order Phlebobranchiata). Sedimentation exposure is expected to induce up-regulation of anaerobic metabolism by obstructing the organs of gas exchange (environmental hypoxia) or causes enhanced squirting activity (functional hypoxia). In this study we evaluated the possible relationship between ascidian morphotype and their physiological response to sedimentation. Together with some behavioural observations, we analysed the response of anaerobic metabolic parameters (lactate formation and glycogen consumption) in different tissues of three Antarctic ascidians, exposed to high sediment concentrations (200 mgL(-1)). The results were compared to experimental hypoxia (10% pO2) and exercise (induced muscular contraction) effects, in order to discriminate the effect of sediment on each species and morpho-type (erect vs. flat forms). Our results suggest that the styled (erect) C. verrucosa increases muscular squirting activity in order to expulse excessive material, while the flat-form A. challengeri reacts more passively by down-regulating its aerobic metabolism under sediment exposure. Contrary, the erect ascidian M. pedunculata did not show any measurable response to the treatments, indicating that filtration and ingestion activities were not reduced or altered even under high sedimentation (low energetic material) which could be disadvantageous on the long-term and could explain why M. pedunculata densities decline in the study area. Copyright © 2014 Elsevier Ltd. All rights reserved.

Habitat niche breadth predicts invasiveness in solitary ascidians.

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Granot, Itai; Shenkar, Noa; Belmaker, Jonathan

2017-10-01

A major focus of invasion biology is understanding the traits associated with introduction success. Most studies assess these traits in the invaded region, while only few compare nonindigenous species to the pool of potential invaders in their native region. We focused on the niche breadth hypothesis , commonly evoked but seldom tested, which states that generalist species are more likely to become introduced as they are capable of thriving under a wide set of conditions. Based on the massive introduction of tropical species into the Mediterranean via the Suez Canal (Lessepsian migration), we defined ascidians in the Red Sea as the pool of potential invaders. We constructed unique settlement plates, each representing six different niches, to assess ascidian niche breadth, and deployed them in similar habitats in the native and invaded regions. For each species found on plates, we evaluated its abundance, relative abundance across successional stages, and niche breadth, and then compared (1) species in the Red Sea known to have been introduced into the Mediterranean (Lessepsian species) and those not known from the Mediterranean (non-Lessepsian); and (2) nonindigenous and indigenous species in the Mediterranean. Lessepsian species identified on plates in the Red Sea demonstrated wider niche breadth than non-Lessepsian species, supporting the niche breadth hypothesis within the native region. No differences were found between Lessepsian and non-Lessepsian species in species abundance and successional stages. In the Mediterranean, nonindigenous species numerically dominated the settlement plates. This precluded robust comparisons of niche breadth between nonindigenous and indigenous species in the invaded region. In conclusion, using Red Sea ascidians as the pool of potential invaders, we found clear evidence supporting the niche breadth hypothesis in the native region. We suggest that such patterns may often be obscured when conducting trait-based studies in the

Chondroitin 6-O-sulfotransferases are required for morphogenesis of the notochord in the ascidian embryo.

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Nakamura, Jun; Yoshida, Keita; Sasakura, Yasunori; Fujiwara, Shigeki

2014-12-01

Chondroitin sulfate (CS) is a sulfated polysaccharide chain that binds to various core proteins to form proteoglycans. The amount and position of sulfate groups in CS are variable among different tissues, and are determined by specific sulfotransferases. Although the ascidians are the closest relatives of vertebrates, the functions of their sulfotransferases have not been studied. The genome of the ascidian Ciona intestinalis contains eight genes encoding proteins similar to chondroitin 6-O-sulfotransferases (C6STs), which appear to have independently diverged in the ascidian lineage during evolution. Among them, Ci-C6ST-like1 and Ci-C6ST-like7 were predominantly expressed in the developing notochord. In addition, they were weakly expressed in the neural tube. The disruption of either one of them affected the convergent extension movement of notochordal cells. Presumptive notochord cells coming from both sides of the embryo did not intercalate. The results suggest that both of them are necessary. In some cases, the anterior neural tube failed to close. Forced expression of Ci-C6ST-like1 or Ci-C6ST-like7 in the notochord restored the normal intercalation of notochordal cells, indicating that the effects of morpholino oligos are specific. Ci-C6ST-like1 and Ci-C6ST-like7 are required for the morphogenesis of the notochord in the ascidian embryo. © 2014 Wiley Periodicals, Inc.

Urochordate ascidians possess a single isoform of Aurora kinase that localizes to the midbody via TPX2 in eggs and cleavage stage embryos.

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Celine Hebras

Full Text Available Aurora kinases are key proteins found throughout the eukaryotes that control mitotic progression. Vertebrate Aurora-A and B kinases are thought to have evolved from a single Aurora-kinase isoform closest to that found in present day urochordates. In urochordate ascidians Aurora binds both TPX2 (a vertebrate AURKA partner and INCENP (a vertebrate AURKB partner and localizes to centrosomes and spindle microtubules as well as chromosomes and midbody during both meiosis and mitosis. Ascidian Aurora also displays this localization pattern during mitosis in echinoderms, strengthening the idea that non-vertebrate deuterostomes such as the urochordates and echinoderms possess a single form of Aurora kinase that has properties of vertebrate Aurora-kinase A and B. In the ascidian, TPX2 localizes to the centrosome and the spindle poles also as in vertebrates. However, we were surprised to find that TPX2 also localized strongly to the midbody in ascidian eggs and embryos. We thus examined more closely Aurora localization to the midbody by creating two separate point mutations of ascidian Aurora predicted to perturb binding to TPX2. Both forms of mutated Aurora behaved as predicted: neither localized to spindle poles where TPX2 is enriched. Interestingly, neither form of mutated Aurora localized to the midbody where TPX2 is also enriched, suggesting that ascidian Aurora midbody localization required TPX2 binding in ascidians. Functional analysis revealed that inhibition of Aurora kinase with a pharmacological inhibitor or with a dominant negative kinase dead form of Aurora caused cytokinesis failure and perturbed midbody formation during polar body extrusion. Our data support the view that vertebrate Aurora-A and B kinases evolved from a single non-vertebrate deuterostome ancestor. Moreover, since TPX2 localizes to the midbody in ascidian eggs and cleavage stage embryos it may be worthwhile re-assessing whether Aurora A kinase or TPX2 localize to the midbody

Amino Alcohols from the Ascidian Pseudodistoma sp.

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Tae Hyung Won

2014-06-01

Full Text Available Seven new amino alcohol compounds, pseudoaminols A–G (1–7, were isolated from the ascidian Pseudodistoma sp. collected off the coast of Chuja-do, Korea. Structures of these new compounds were determined by analysis of the spectroscopic data and from chemical conversion. The presence of an N-carboxymethyl group in two of the new compounds (6 and 7 is unprecedented among amino alcohols. Several of these compounds exhibited moderate antimicrobial activity and cytotoxicity, as well as weak inhibitory activity toward Na+/K+-ATPase.

Description of Endozoicomonas ascidiicola sp. nov., isolated from Scandinavian ascidians

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Schreiber, Lars; Kjeldsen, Kasper Urup; Obst, Matthias

2016-01-01

Two gram-negative, facultative anaerobic, chemoorganoheterotrophic, motile and rod-shaped bacteria, strains AVMART05T and KASP37, were isolated from ascidians (Tunicata, Ascidiaceae) of the genus Ascidiella collected at Gullmarsfjord, Sweden. The strains are the first cultured representatives...

Cytotoxicity of the Ascidian Cystodytes dellechiajei Against Tumor Cells and Study of the Involvement of Associated Microbiota in the Production of Cytotoxic Compounds

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Josefa Antón

2007-07-01

Full Text Available Many cytotoxic compounds of therapeutic interest have been isolated from marine invertebrates, and some of them have been reported to be of microbial origin. Pyridoacridine alkaloids are the main compounds extracted from the ascidian Cystodytes dellechiajei. Here we describe the in vitro antiproliferative activity against different tumor cell lines of the ascidian extracts and provide some insights on the role of the microbial community associated with the tunicate in the production of these compounds. C. dellechiajei extracts showed remarkably high antiproliferative activity (IC50 ≤5 μg/mL in human lung carcinoma A-549, colon adenocarcinoma H-116, pancreatic adenocarcinoma PSN-1 and breast carcinoma SKBR3 cell lines. Moreover, we found that the maximum activity was located in the tunic tissue of the colony, which harbours a microbial community. In order to ascertain the involvement of this community in the synthesis of the bioactive compounds different approachs that included culture and culture independent methods were carried out. We undertook a screening for antiproliferative activities of the bacterial isolates from the ascidian, as well as a comprative analysis of the cytotoxic activities and the microbial communities from two color morphs of the ascidian, green and blue. In addition, the changes of the antiproliferative activities and the composition of the microbial communities were studied from ascidians kept in aquaria and treated with antibiotics for one month. Our data obtained from the different experiments did not point out to bacteria as the source of the cytotoxic compounds, suggesting thus an ascidian origin.

Toxicity of marine pollutants on the ascidian oocyte physiology: an electrophysiological approach.

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Gallo, Alessandra

2018-02-01

In marine animals with external fertilization, gametes are released into seawater where fertilization and embryo development occur. Consequently, pollutants introduced into the marine environment by human activities may affect gametes and embryos. These xenobiotics can alter cell physiology with consequent reduction of fertilization success. Here the adverse effects on the reproductive processes of the marine invertebrate Ciona intestinalis (ascidian) of different xenobiotics: lead, zinc, an organic tin compound and a phenylurea herbicide were evaluated. By using the electrophysiological technique of whole-cell voltage clamping, the effects of these compounds on the mature oocyte plasma membrane electrical properties and the electrical events of fertilization were tested by calculating the concentration that induced 50% normal larval formation (EC50). The results demonstrated that sodium currents in mature oocytes were reduced in a concentration-dependent manner by all tested xenobiotics, with the lowest EC50 value for lead. In contrast, fertilization current frequencies were differently affected by zinc and organic tin compound. Toxicity tests on gametes demonstrated that sperm fertilizing capability and fertilization oocyte competence were not altered by xenobiotics, whereas fertilization was inhibited in zinc solution and underwent a reduction in organic tin compound solution (EC50 value of 1.7 µM). Furthermore, fertilized oocytes resulted in a low percentage of normal larvae with an EC50 value of 0.90 µM. This study shows that reproductive processes of ascidians are highly sensitive to xenobiotics suggesting that they may be considered a reliable biomarker and that ascidians are suitable model organisms to assess marine environmental quality.

Screening for negative effects of candidate ascidian antifoulant compounds on a target aquaculture species, Perna canaliculus Gmelin.

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Cahill, Patrick Louis; Heasman, Kevin; Hickey, Anthony; Mountfort, Douglas; Jeffs, Andrew; Kuhajek, Jeannie

2013-01-01

The natural chemical compounds radicicol, polygodial and ubiquinone-10 (Q10) have previously been identified as inhibitors of metamorphosis in ascidian larvae. Accordingly, they have potential as a specific remedy for the costly problem of fouling ascidians in bivalve aquaculture. In this study, these compounds were screened for their effects on the physiological health of an aquaculture species, the green-lipped mussel, Perna canaliculus Gmelin, at or above the 99% effective dose (IC(99)) in ascidians. Three physiological biomarkers of mussel health were screened: growth (increases in shell height and wet weight), condition (condition index) and mitochondrial respirational function (Complex I-mediated respiration, Complex II-mediated respiration, maximum uncoupled respiration, leak respiration, respiratory control ratios and phosphorylation system control ratios). While polygodial and Q10 had no effect on mussel growth or the condition index, radicicol retarded growth and decreased the condition index. Mitochondrial respirational function was unaffected by radicicol and polygodial. Conversely, Q10 enhanced Complex I-mediated respiration, highlighting the fundamental role of this compound in the electron transport system. The present study suggests that polygodial and Q10 do not negatively affect the physiological health of P. canaliculus at the IC(99) in ascidians, while radicicol is toxic. Moreover, Q10 is of benefit in biomedical settings as a cellular antioxidant and therefore may also benefit P. canaliculus. Accordingly, polygodial and Q10 should be progressed to the next stage of testing where possible negative effects on bivalves will be further explored, followed by development of application techniques and testing in a laboratory and aquaculture setting.

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes.

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Carroll, Michael; Levasseur, Mark; Wood, Chris; Whitaker, Michael; Jones, Keith T; McDougall, Alex

2003-12-15

In ascidians, as in mammals, sperm trigger repetitive Ca2+-waves that originate from cortical pacemakers situated in the vegetal hemisphere of the zygotes. In ascidians, a vegetal protrusion termed the contraction pole (CP) acts as the Ca2+-wave pacemaker, but the mechanism that underlies the generation of a Ca2+-wave pacemaker is not known. Here, we tested four hypotheses to determine which factors at the CP are involved in setting the pace of the ascidian Ca2+-wave pacemaker: (1) localized Ca2+ influx; (2) accumulation of phosphatidylinositol (4,5)bisphosphate [PtdIns(4,5)P2]; (3) accumulation of cortical endoplasmic reticulum (cER); and (4) enrichment of the sperm activating factor. We developed a method of dynamically monitoring the location of the CP during fertilization using a plekstrin homology (PH) domain from phospholipase Cdelta1 coupled to green fluorescent protein (GFP) that binds PtdIns(4,5)P2. We found that eggs in Ca2+-free sea water displayed Ca2+ waves that originated from the CP, showing that enhanced CP Ca2+ influx does not determine the origin of the pacemaker. Also, disruption of the PH::GFP-labelled CP once it had formed did not dislodge the Ca2+-wave pacemaker from that site. Next, when we prevented the accumulation of cER at the CP, all of the Ca2+ waves came from the site of sperm-egg fusion and the frequency of Ca2+ oscillations was unaltered. These data show that local Ca2+ influx, the accumulation of PtdIns(4,5)P2 and cER at the CP are not required for Ca2+-wave pacemaker function and instead suggest that a factor associated with the sperm determines the site of the Ca2+-wave pacemaker. Finally, when we injected ascidian sperm extract into the centre of unfertilized ascidian eggs that had been treated with microfilament- and microtubule-disrupting drugs, all the Ca2+ waves still originated from near the plasma membrane, showing that the sperm factor does not require an intact cortex if it is enriched near the plasma membrane (PM). We

Microenvironmental Ecology of the Chlorophyll b-containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella

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Michael eKühl

2012-11-01

Full Text Available The discovery of the cyanobacterium Prochloron was the first finding of a bacterial oxyphototroph with chlorophyll (Chl b, in addition to Chl a. It was first described as Prochloron didemni but a number of clades have since been described. Prochloron is a conspicuously large (7-25 µm unicellular cyanobacterium living in a symbiotic relationship, primarily with (sub- tropical didemnid ascidians; it has resisted numerous cultivation attempts and appears truly obligatory symbiotic. Recently, a Prochloron draft genome was published, revealing no lack of metabolic genes that could explain the apparent inability to reproduce and sustain photosynthesis in a free-living stage. Possibly, the unsuccessful cultivation is partly due to a lack of knowledge about the microenvironmental conditions and ecophysiology of Prochloron in its natural habitat. We used microsensors, variable chlorophyll fluorescence imaging and imaging of O2 and pH to obtain a detailed insight to the microenvironmental ecology and photobiology of Prochloron in hospite in the didemnid ascidian Lissoclinum patella. The microenvironment within ascidians is characterized by steep gradients of light and chemical parameters that change rapidly with varying irradiances. The interior zone of the ascidians harboring Prochloron thus became anoxic and acidic within a few min of darkness, while the same zone exhibited O2 super-saturation and strongly alkaline pH after a few min of illumination. Photosynthesis showed lack of photoinhibition even at high irradiances equivalent to full sunlight, and photosynthesis recovered rapidly after periods of anoxia. We discuss these new insights on the ecological niche of Prochloron and possible interactions with its host and other microbes in light of its recently published genome and a recent study of the overall microbial diversity and metagenome of L. patella.

Whole-organ cell shape analysis reveals the developmental basis of ascidian notochord taper.

Science.gov (United States)

Veeman, Michael T; Smith, William C

2013-01-15

Here we use in toto imaging together with computational segmentation and analysis methods to quantify the shape of every cell at multiple stages in the development of a simple organ: the notochord of the ascidian Ciona savignyi. We find that cell shape in the intercalated notochord depends strongly on anterior-posterior (AP) position, with cells in the middle of the notochord consistently wider than cells at the anterior or posterior. This morphological feature of having a tapered notochord is present in many chordates. We find that ascidian notochord taper involves three main mechanisms: Planar Cell Polarity (PCP) pathway-independent sibling cell volume asymmetries that precede notochord cell intercalation; the developmental timing of intercalation, which proceeds from the anterior and posterior towards the middle; and the differential rates of notochord cell narrowing after intercalation. A quantitative model shows how the morphology of an entire developing organ can be controlled by this small set of cellular mechanisms. Copyright © 2012 Elsevier Inc. All rights reserved.

Inverse correlation of population similarity and introduction date for invasive ascidians.

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Nathan Silva

2008-06-01

Full Text Available The genomes of many marine invertebrates, including the purple sea urchin and the solitary ascidians Ciona intestinalis and Ciona savignyi, show exceptionally high levels of heterozygosity, implying that these populations are highly polymorphic. Analysis of the C. savignyi genome found little evidence to support an elevated mutation rate, but rather points to a large population size contributing to the polymorphism level. In the present study, the relative genetic polymorphism levels in sampled populations of ten different ascidian species were determined using a similarity index generated by AFLP analysis. The goal was to determine the range of polymorphism within the populations of different species, and to uncover factors that may contribute to the high level of polymorphism. We observe that, surprisingly, the levels of polymorphism within these species show a negative correlation with the reported age of invasive populations, and that closely related species show substantially different levels of genetic polymorphism. These findings show exceptions to the assumptions that invasive species start with a low level of genetic polymorphism that increases over time and that closely related species have similar levels of genetic polymorphism.

Ascidian introductions through the Suez Canal: The case study of an Indo-Pacific species.

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Rius, Marc; Shenkar, Noa

2012-10-01

Although marine biological invasions via the Suez Canal have been extensively documented, little is known about the introduction of non-indigenous ascidians (Chordata, Ascidiacea), a group containing particularly aggressive invasive species. Here, we used a multidisciplinary approach to study the introduction of the ascidian Herdmania momus into the Mediterranean Sea. We reviewed its taxonomy and global distribution, and analyzed how genetic variation is partitioned between sides of the Suez Canal. The taxonomic revision showed that H. momus currently has a wide Indo-Pacific distribution. Genetic data indicated two well-differentiated colonization histories across the eastern Mediterranean. Our findings suggest that the range expansion of H. momus has been greatly facilitated by the combined effect of human-mediated transport and the species' ability to adapt to different environments. The integrative approach presented here is critical to attain a holistic understanding of marine biological invasions, especially when studying groups with a poorly resolved taxonomy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cytoskeletal actin genes function downstream of HNF-3beta in ascidian notochord development.

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Jeffery, W R; Ewing, N; Machula, J; Olsen, C L; Swalla, B J

1998-11-01

We have examined the expression and regulation of cytoskeletal actin genes in ascidians with tailed (Molgula oculata) and tailless larvae (Molgula occulta). Four cDNA clones were isolated representing two pairs of orthologous cytoskeletal actin genes (CA1 and CA2), which encode proteins differing by five amino acids in the tailed and tailless species. The CA1 and CA2 genes are present in one or two copies, although several related genes may also be present in both species. Maternal CA1 and CA2 mRNA is present in small oocytes but transcript levels later decline, suggesting a role in early oogenesis. In the tailed species, embryonic CA1 and CA2 mRNAs first appear in the presumptive mesenchyme and muscle cells during gastrulation, subsequently accumulate in the presumptive notochord cells, and can be detected in these tissues through the tadpole stage. CA1 mRNAs accumulate initially in the same tissues in the tailless species but subsequently disappear, in concert with the arrest of notochord and tail development. In contrast, CA2 mRNAs were not detected in embryos of the tailless species. Fertilization of eggs of the tailless species with sperm of the tailed species, which restores the notochord and the tail, also results in the upregulation of CA1 and CA2 gene expression in hybrid embryos. Antisense oligodeoxynucleotide experiments suggest that CA1 and CA2 expression in the notochord, but not in the muscle cells, is dependent on prior expression of Mocc FHI, an ascidian HNF-3beta-like gene. The expression of the CA1 and CA2 genes in the notochord in the tailed species, downregulation in the tailless species, upregulation in interspecific hybrids, and dependence on HNF-3beta activity is consistent with a role of these genes in development of the ascidian notochord.

Natural Products from Antarctic Colonial Ascidians of the Genera Aplidium and Synoicum: Variability and Defensive Role

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Conxita Avila

2012-08-01

Full Text Available Ascidians have developed multiple defensive strategies mostly related to physical, nutritional or chemical properties of the tunic. One of such is chemical defense based on secondary metabolites. We analyzed a series of colonial Antarctic ascidians from deep-water collections belonging to the genera Aplidium and Synoicum to evaluate the incidence of organic deterrents and their variability. The ether fractions from 15 samples including specimens of the species A. falklandicum, A. fuegiense, A. meridianum, A. millari and S. adareanum were subjected to feeding assays towards two relevant sympatric predators: the starfish Odontaster validus, and the amphipod Cheirimedon femoratus. All samples revealed repellency. Nonetheless, some colonies concentrated defensive chemicals in internal body-regions rather than in the tunic. Four ascidian-derived meroterpenoids, rossinones B and the three derivatives 2,3-epoxy-rossinone B, 3-epi-rossinone B, 5,6-epoxy-rossinone B, and the indole alkaloids meridianins A–G, along with other minoritary meridianin compounds were isolated from several samples. Some purified metabolites were tested in feeding assays exhibiting potent unpalatabilities, thus revealing their role in predation avoidance. Ascidian extracts and purified compound-fractions were further assessed in antibacterial tests against a marine Antarctic bacterium. Only the meridianins showed inhibition activity, demonstrating a multifunctional defensive role. According to their occurrence in nature and within our colonial specimens, the possible origin of both types of metabolites is discussed.

Comparative study on bioremediation of heavy metals by solitary ascidian, Phallusia nigra, between Thoothukudi and Vizhinjam ports of India.

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Abdul Jaffar Ali, H; Tamilselvi, M; Akram, A Soban; Kaleem Arshan, M L; Sivakumar, V

2015-11-01

Ascidians belonging to the sub-phylum Uro-chordata are used as potential model organisms in various parts of the world for biosorption of metals. The sedentary nature, filter feeding habits, presence of vanadocytes and the absence of kidneys cause them to accumulate metals. The present study was aimed to compare biosorption of metals such as cadmium, copper, lead, mercury and vanadium in test and mantle body of solitary ascidian Phallusia nigra between two ecologically significant stations such as Thoothukudi (Station 1) and Vizhinjam (Station 2) ports of India. Monthly samplings of water and P. nigra were done for a period of one year from September 2010 to August 2011 and subjected to analysis of metal accumulation. The average metal concentrations except mercury in the Thoothukudi water were found to be higher of comparable magnitudes than the Vizhinjam water. One-way ANOVA showed significant differences between the stations. A comparison of average metal concentrations in the test and mantle body of P. nigra between two stations showed that the enrichment of V, Cd, Pb, Cu and Hg in the Thoothukudi samples may be due to high bioaccumulation factors of these elements as compared to other species of ascidians. The bioaccumulation factors were in the order of V>Pb>Cd>Cu> Hg for the test and mantle body in stations 1 and 2. Application of one-way ANOVA for the concentration of these metals between test and mantle body showed significant differences in both stations. Similarly, ANOVA for biosorption of these trace metals by P. nigra showed significant difference between stations. Metal concentrations recorded in this ascidian could effectively be used as good reference material for monitoring metal contamination in Indian sea waters. Copyright © 2015 Elsevier Inc. All rights reserved.

When shape matters: strategies of different Antarctic ascidians morphotypes to deal with sedimentation

OpenAIRE

Torre, Luciana; Abele, Doris; Lagger, Cristian; Momo, Fernando; Sahade, Ricardo

2014-01-01

Climate change leads to increased melting of tidewater glaciers in theWestern Antarctic Peninsula region and sediment bearing glacial melt waters negatively affects filter feeding species as solitary ascidians. In previous work the erect-forms Molgula pedunculata and Cnemidocarpa verrucosa (Order Stolidobranchiata) appeared more sensitive than the flat form Ascidia challengeri (Order Phlebobranchiata). Sedimentation exposure is expected to induce up-regulation of anaerobic metabol...

Large-scale infection of the ascidian Ciona intestinalis by the gregarine Lankesteria ascidiae in an inland culture system.

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Mita, Kaoru; Kawai, Narudo; Rueckert, Sonja; Sasakura, Yasunori

2012-11-19

An important way to keep transgenic and mutant lines of the ascidian Ciona intestinalis, a model system for e.g. genetic functions, in laboratories is via culturing systems. Here we report a disease of C. intestinalis observed in an inland culturing system. The disease, called 'long feces syndrome,' is expressed in affected animals by the following characteristic symptoms of the digestive system: (1) excretion of long and thin feces, (2) pale color of the stomach, and (3) congestion of the digestive tube by digested material. Severely diseased animals usually die within a week after the first symptoms occur, implying a high risk of this disease for ascidian culturing systems. The digestive tubes of the diseased animals are occupied by the gregarine apicomplexan parasite Lankesteria ascidiae, suggesting that large-scale infection by this parasite is the cause of long feces syndrome.

The pharmaceutical exploration of cold water ascidians from the Netherlands : a possible source of new cytotoxic natural products

NARCIS (Netherlands)

Koulman, A; Pruijn, L.M C; Sandstra, T.C A; Woerdenbag, H.J.; Pras, N.

1999-01-01

Six ascidian species from the Dutch North Sea coast were screened for cytotoxic activity, Freeze-dried biological material was extracted with solvents of different polarity followed by determination of the cytotoxicity. The most active extracts were further separated using different chromatographic

Tenacibaculum ascidiaceicola sp. nov., isolated from the golden sea squirt Halocynthia aurantium.

Science.gov (United States)

Kim, Young-Ok; Park, In-Suk; Park, Sooyeon; Nam, Bo-Hye; Park, Ji-Min; Kim, Dong-Gyun; Yoon, Jung-Hoon

2016-03-01

A Gram-stain-negative, non-flagellated, non-spore-forming bacterial strain motile by gliding, designated RSS1-6T, was isolated from a golden sea squirt Halocynthia aurantium and its taxonomic position was investigated by using a polyphasic approach. Strain RSS1-6T grew optimally at 30-37 °C and in the presence of 1.0-4.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences showed that strain RSS1-6T fell within the clade comprising species of the genus Tenacibaculum, clustering with the type strains of Tenacibaculum discolor, Tenacibaculum litoreum and Tenacibaculum gallaicum with which it exhibited 16S rRNA gene sequence similarity values of 98.5-99.5 %. Strain RSS1-6T contained MK-6 as the predominant menaquinone and iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as the major fatty acids. The major polar lipids of strain RSS1-6T were phosphatidylethanolamine, two unidentified lipids, one unidentified aminophospholipid and one unidentified glycolipid. The DNA G+C content was 32.5 mol% and the mean DNA-DNA relatedness values with the type strains of T. discolor, T. litoreum and T. gallaicum were 17.3-25.2 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain RSS1-6T is separated from other recognized species of the genus Tenacibaculum. On the basis of the data presented, strain RSS1-6T is considered to represent a novel species of the genus Tenacibaculum, for which the name Tenacibaculum ascidiaceicola sp. nov. is proposed. The type strain is RSS1-6T ( = KCTC 42702T = NBRC 111225T).

Whole-organ cell shape analysis reveals the developmental basis of ascidian notochord taper

OpenAIRE

Veeman, Michael T.; Smith, William C.

2013-01-01

Here we use in toto imaging together with computational segmentation and analysis methods to quantify the shape of every cell at multiple stages in the development of a simple organ: the notochord of the ascidian Ciona savignyi. We find that cell shape in the intercalated notochord depends strongly on anterior-posterior (AP) position, with cells in the middle of the notochord consistently wider than cells at the anterior or posterior. This morphological feature of having a tapered notochord i...

Expression of an Msx homeobox gene in ascidians: insights into the archetypal chordate expression pattern.

Science.gov (United States)

Ma, L; Swalla, B J; Zhou, J; Dobias, S L; Bell, J R; Chen, J; Maxson, R E; Jeffery, W R

1996-03-01

The Msx homeobox genes are expressed in complex patterns during vertebrate development in conjunction with inductive tissue interactions. As a means of understanding the archetypal role of Msx genes in chordates, we have isolated and characterized an Msx gene in ascidians, protochordates with a relatively simple body plan. The Mocu Msx-a and McMsx-a genes, isolated from the ascidians Molgula oculata and Molgula citrina, respectively, have homeodomains that place them in the msh-like subclass of Msx genes. Therefore, the Molgula Msx-a genes are most closely related to the msh genes previously identified in a number of invertebrates. Southern blot analysis suggests that there are one or two copies of the Msx-a gene in the Molgula genome. Northern blot and RNase protection analysis indicate that Msx-a transcripts are restricted to the developmental stages of the life cycle. In situ hybridization showed that Msx-a mRNA first appears just before gastrulation in the mesoderm (presumptive notochord and muscle) and ectoderm (neural plate) cells. Transcript levels decline in mesoderm cells after the completion of gastrulation, but are enhanced in the folding neural plate during neurulation. Later, Msx-a mRNA is also expressed in the posterior ectoderm and in a subset of the tail muscle cells. The ectoderm and mesoderm cells that express Msx-a are undergoing morphogenetic movements during gastrulation, neurulation, and tail formation. Msx-a expression ceases after these cells stop migrating. The ascidian M. citrina, in which adult tissues and organs begin to develop precociously in the larva, was used to study Msx-a expression during adult development. Msx-a transcripts are expressed in the heart primordium and the rudiments of the ampullae, epidermal protrusions with diverse functions in the juvenile. The heart and ampullae develop in regions where mesenchyme cells interact with endodermal or epidermal epithelia. A comparison of the expression patterns of the Molgula genes

Nitric oxide acts as a positive regulator to induce metamorphosis of the ascidian Herdmania momus.

Science.gov (United States)

Ueda, Nobuo; Degnan, Sandie M

2013-01-01

Marine invertebrates commonly have a biphasic life cycle in which the metamorphic transition from a pelagic larva to a benthic post-larva is mediated by the nitric oxide signalling pathway. Nitric oxide (NO) is synthesised by nitric oxide synthase (NOS), which is a client protein of the molecular chaperon heat shock protein 90 (HSP90). It is notable, then, that both NO and HSP90 have been implicated in regulating metamorphosis in marine invertebrates as diverse as urochordates, echinoderms, molluscs, annelids, and crustaceans. Specifically, the suppression of NOS activity by the application of either NOS- or HSP90-inhibiting pharmacological agents has been shown consistently to induce the initiation of metamorphosis, leading to the hypothesis that a negative regulatory role of NO is widely conserved in biphasic life cycles. Further, the induction of metamorphosis by heat-shock has been demonstrated for multiple species. Here, we investigate the regulatory role of NO in induction of metamorphosis of the solitary tropical ascidian, Herdmania momus. By coupling pharmacological treatments with analysis of HmNOS and HmHSP90 gene expression, we present compelling evidence of a positive regulatory role for NO in metamorphosis of this species, in contrast to all existing ascidian data that supports the hypothesis of NO as a conserved negative regulator of metamorphosis. The exposure of competent H. momus larvae to a NOS inhibitor or an NO donor results in an up-regulation of NOS and HSP90 genes. Heat shock of competent larvae induces metamorphosis in a temperature dependent manner, up to a thermal tolerance that approaches 35°C. Both larval/post-larval survival and the appearance of abnormal morphologies in H. momus post-larvae reflect the magnitude of up-regulation of the HSP90 gene in response to heat-shock. The demonstrated role of NO as a positive metamorphic regulator in H. momus suggests the existence of inter-specific adaptations of NO regulation in ascidian

Dual mechanism controls asymmetric spindle position in ascidian germ cell precursors.

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Prodon, François; Chenevert, Janet; Hébras, Céline; Dumollard, Rémi; Faure, Emmanuel; Gonzalez-Garcia, Jose; Nishida, Hiroki; Sardet, Christian; McDougall, Alex

2010-06-01

Mitotic spindle orientation with respect to cortical polarity cues generates molecularly distinct daughter cells during asymmetric cell division (ACD). However, during ACD it remains unknown how the orientation of the mitotic spindle is regulated by cortical polarity cues until furrowing begins. In ascidians, the cortical centrosome-attracting body (CAB) generates three successive unequal cleavages and the asymmetric segregation of 40 localized postplasmic/PEM RNAs in germ cell precursors from the 8-64 cell stage. By combining fast 4D confocal fluorescence imaging with gene-silencing and classical blastomere isolation experiments, we show that spindle repositioning mechanisms are active from prometaphase until anaphase, when furrowing is initiated in B5.2 cells. We show that the vegetal-most spindle pole/centrosome is attracted towards the CAB during prometaphase, causing the spindle to position asymmetrically near the cortex. Next, during anaphase, the opposite spindle pole/centrosome is attracted towards the border with neighbouring B5.1 blastomeres, causing the spindle to rotate (10 degrees /minute) and migrate (3 microm/minute). Dynamic 4D fluorescence imaging of filamentous actin and plasma membrane shows that precise orientation of the cleavage furrow is determined by this second phase of rotational spindle displacement. Furthermore, in pairs of isolated B5.2 blastomeres, the second phase of rotational spindle displacement was lost. Finally, knockdown of PEM1, a protein localized in the CAB and required for unequal cleavage in B5.2 cells, completely randomizes spindle orientation. Together these data show that two separate mechanisms active during mitosis are responsible for spindle positioning, leading to precise orientation of the cleavage furrow during ACD in the cells that give rise to the germ lineage in ascidians.

Epimerization of D-glucose to L-galactose during the biosynthesis of a sulfated L-galactan in the ascidian tunic

International Nuclear Information System (INIS)

Mourao, P.A.S.

1991-01-01

The sulfated polysaccharides occurring in the tunic of ascidians are unique among known sulfated polysaccharides in that their major constituent sugar is galactose, which occurs exclusively in the L-enantiomeric form. In vitro incorporation experiments using tunic slices incubated with 14 C-labeled sugars revealed that cells from this tissue epimerize D-isomers of hexose into L-galactose during the biosynthesis of their constituent polysaccharides. Compared with other hexoses, the precursor D-[ 14 C]glucose has the highest rate of incorporation and produces the highest proportion of L-galactose units. This metabolic pathway is distinct from the epimerization of D-mannose to L-galactose through its guanosine 5'-diphosphate nucleotide, described previously in an alga and in a snail. Therefore, the epimerization of D-glucose to L-galactose in the ascidian tunic occurs through a novel metabolic route, which involves inversion of the configuration of carbon atoms 2, 3, and 5 of the hexosyl moieties

Antibacterial modified diketopiperazines from two ascidians of the genus Didemnum

International Nuclear Information System (INIS)

Kossuga, Miriam H.; Lira, Simone P.; McHugh, Shayna; Torres, Yohandra R.; Berlinck, Roberto G.S.; Lima, Bruna A.; Goncalves, Reginaldo; Veloso, Katyuscya; Ferreira, Antonio G.; Rocha, Rosana M.

2009-01-01

The chemical investigation of the crude extract of an ascidian of the genus Didemnum led to the isolation of the modified diketopiperazine rodriguesines A (1) and (2) as a mixture of homologues, which could be identified by analysis of spectroscopic data including MS/MS experiments. The investigation of a second Didemnum sp. led to the isolation of N-acetyl-rodriguesine A (3) and N-acetyl-rodriguesine B (4). The absolute configuration of compounds 1 and 2 could be established by hydrolysis and Marfey's analysis and comparison with literature data reported for compound 3, previously obtained as a synthetic product. The mixture of 1 and 2 displayed moderate antibiotic activity against a clinical isolate of Streptococcus mutans and against S. mutans UA159 and Staphylococcus aureus ATCC6538. (author)

Antibacterial modified diketopiperazines from two ascidians of the genus Didemnum

Energy Technology Data Exchange (ETDEWEB)

Kossuga, Miriam H.; Lira, Simone P.; McHugh, Shayna; Torres, Yohandra R.; Berlinck, Roberto G.S. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Quimica; Lima, Bruna A.; Goncalves, Reginaldo [Universidade Estadual de Campinas, Piracicaba, SP (Brazil). Faculdade de Odontologia. Dept. de Diagnostico Oral; Veloso, Katyuscya; Ferreira, Antonio G. [Universidade Federal de Sao Carlos, SP (Brazil). Dept. de Quimica; Rocha, Rosana M. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Centro Politecnico. Setor de Ciencias Biologicas. Dept. de Zoologia

2009-07-01

The chemical investigation of the crude extract of an ascidian of the genus Didemnum led to the isolation of the modified diketopiperazine rodriguesines A (1) and (2) as a mixture of homologues, which could be identified by analysis of spectroscopic data including MS/MS experiments. The investigation of a second Didemnum sp. led to the isolation of N-acetyl-rodriguesine A (3) and N-acetyl-rodriguesine B (4). The absolute configuration of compounds 1 and 2 could be established by hydrolysis and Marfey's analysis and comparison with literature data reported for compound 3, previously obtained as a synthetic product. The mixture of 1 and 2 displayed moderate antibiotic activity against a clinical isolate of Streptococcus mutans and against S. mutans UA159 and Staphylococcus aureus ATCC6538. (author)

Polarity and reorganization of the endoplasmic reticulum during fertilization and ooplasmic segregation in the ascidian egg

OpenAIRE

1993-01-01

During the first cell cycle of the ascidian egg, two phases of ooplasmic segregation create distinct cytoplasmic domains that are crucial for later development. We recently defined a domain enriched in ER in the vegetal region of Phallusia mammillata eggs. To explore the possible physiological and developmental function of this ER domain, we here investigate its organization and fate by labeling the ER network in vivo with DiIC16(3), and observing its distribution before and after fertilizati...

Identification of Eusynstyelamide B as a Potent Cell Cycle Inhibitor Following the Generation and Screening of an Ascidian-Derived Extract Library Using a Real Time Cell Analyzer

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Michelle S. Liberio

2014-10-01

Full Text Available Ascidians are marine invertebrates that have been a source of numerous cytotoxic compounds. Of the first six marine-derived drugs that made anticancer clinical trials, three originated from ascidian specimens. In order to identify new anti-neoplastic compounds, an ascidian extract library (143 samples was generated and screened in MDA-MB-231 breast cancer cells using a real-time cell analyzer (RTCA. This resulted in 143 time-dependent cell response profiles (TCRP, which are read-outs of changes to the growth rate, morphology, and adhesive characteristics of the cell culture. Twenty-one extracts affected the TCRP of MDA-MB-231 cells and were further investigated regarding toxicity and specificity, as well as their effects on cell morphology and cell cycle. The results of these studies were used to prioritize extracts for bioassay-guided fractionation, which led to the isolation of the previously identified marine natural product, eusynstyelamide B (1. This bis-indole alkaloid was shown to display an IC50 of 5 µM in MDA-MB-231 cells. Moreover, 1 caused a strong cell cycle arrest in G2/M and induced apoptosis after 72 h treatment, making this molecule an attractive candidate for further mechanism of action studies.

Antimalarial β-carbolines from the New Zealand ascidian Pseudodistoma opacum.

Science.gov (United States)

Chan, Susanna T S; Pearce, A Norrie; Page, Michael J; Kaiser, Marcel; Copp, Brent R

2011-09-23

One tetrahydro-β-carboline, (-)-7-bromohomotrypargine (1), and three alkylguanidine-substituted β-carbolines, opacalines A, B, and C (2-4), have been isolated from the New Zealand ascidian Pseudodistoma opacum. The structures of the metabolites were determined by analysis of mass spectrometric and 2D NMR spectroscopic data. Natural products 2 and 3, synthetic debromo analogues 8 and 9, and intermediate 16 exhibited moderate antimalarial activity toward a chloroquine-resistant strain of Plasmodium falciparum, with an IC50 range of 2.5-14 μM. The biosynthesis of 1-4 is proposed to proceed via a Pictet-Spengler condensation of 6-bromotryptamine and the α-keto acid transamination product of either arginine or homoarginine. Cell separation and 1H NMR analysis of P. opacum identified tetrahydro-β-carboline 1 to be principally located in the zooids, while fully aromatized analogues 2-4 were localized to the test.

ANISEED 2017: extending the integrated ascidian database to the exploration and evolutionary comparison of genome-scale datasets.

Science.gov (United States)

Brozovic, Matija; Dantec, Christelle; Dardaillon, Justine; Dauga, Delphine; Faure, Emmanuel; Gineste, Mathieu; Louis, Alexandra; Naville, Magali; Nitta, Kazuhiro R; Piette, Jacques; Reeves, Wendy; Scornavacca, Céline; Simion, Paul; Vincentelli, Renaud; Bellec, Maelle; Aicha, Sameh Ben; Fagotto, Marie; Guéroult-Bellone, Marion; Haeussler, Maximilian; Jacox, Edwin; Lowe, Elijah K; Mendez, Mickael; Roberge, Alexis; Stolfi, Alberto; Yokomori, Rui; Brown, C Titus; Cambillau, Christian; Christiaen, Lionel; Delsuc, Frédéric; Douzery, Emmanuel; Dumollard, Rémi; Kusakabe, Takehiro; Nakai, Kenta; Nishida, Hiroki; Satou, Yutaka; Swalla, Billie; Veeman, Michael; Volff, Jean-Nicolas; Lemaire, Patrick

2018-01-04

ANISEED (www.aniseed.cnrs.fr) is the main model organism database for tunicates, the sister-group of vertebrates. This release gives access to annotated genomes, gene expression patterns, and anatomical descriptions for nine ascidian species. It provides increased integration with external molecular and taxonomy databases, better support for epigenomics datasets, in particular RNA-seq, ChIP-seq and SELEX-seq, and features novel interactive interfaces for existing and novel datatypes. In particular, the cross-species navigation and comparison is enhanced through a novel taxonomy section describing each represented species and through the implementation of interactive phylogenetic gene trees for 60% of tunicate genes. The gene expression section displays the results of RNA-seq experiments for the three major model species of solitary ascidians. Gene expression is controlled by the binding of transcription factors to cis-regulatory sequences. A high-resolution description of the DNA-binding specificity for 131 Ciona robusta (formerly C. intestinalis type A) transcription factors by SELEX-seq is provided and used to map candidate binding sites across the Ciona robusta and Phallusia mammillata genomes. Finally, use of a WashU Epigenome browser enhances genome navigation, while a Genomicus server was set up to explore microsynteny relationships within tunicates and with vertebrates, Amphioxus, echinoderms and hemichordates. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Construction of a cDNA microarray derived from the ascidian Ciona intestinalis.

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Azumi, Kaoru; Takahashi, Hiroki; Miki, Yasufumi; Fujie, Manabu; Usami, Takeshi; Ishikawa, Hisayoshi; Kitayama, Atsusi; Satou, Yutaka; Ueno, Naoto; Satoh, Nori

2003-10-01

A cDNA microarray was constructed from a basal chordate, the ascidian Ciona intestinalis. The draft genome of Ciona has been read and inferred to contain approximately 16,000 protein-coding genes, and cDNAs for transcripts of 13,464 genes have been characterized and compiled as the "Ciona intestinalis Gene Collection Release I". In the present study, we constructed a cDNA microarray of these 13,464 Ciona genes. A preliminary experiment with Cy3- and Cy5-labeled probes showed extensive differential gene expression between fertilized eggs and larvae. In addition, there was a good correlation between results obtained by the present microarray analysis and those from previous EST analyses. This first microarray of a large collection of Ciona intestinalis cDNA clones should facilitate the analysis of global gene expression and gene networks during the embryogenesis of basal chordates.

Proceraea exoryxae sp. nov. (Annelida, Syllidae, Autolytinae, the first known polychaete miner tunneling into the tunic of an ascidian

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Daniel Martin

2017-06-01

Full Text Available While studying organisms living in association with the solitary tunicate Phallusia nigra (Ascidiacea, Ascidiidae from a shallow fringing reef at Zeytouna Beach (Egyptian Red Sea, one of the collected ascidians showed peculiar perforations on its tunic. Once dissected, the perforations revealed to be the openings of a network of galleries excavated in the inner tunic (atrium by at least six individuals of a polychaetous annelid. The worms belonged to the Autolytinae (Syllidae, a subfamily that is well known to include specialized predators and/or symbionts, mostly associated with cnidarians. The Red Sea worms are here described as Proceraea exoryxae sp. nov., which are anatomically distinguished by the combination of simple chaetae only in anterior chaetigers, and a unique trepan with 33 teeth in one outer ring where one large tooth alternates with one medium-sized tricuspid tooth, and one inner ring with small teeth located just behind the large teeth. Male and female epitokes were found together with atokous individuals within galleries. Proceraea exoryxae sp. nov. constitutes the first known miner in the Autolytinae and the second species in this taxon known to live symbiotically with ascidians. The implications of finding this specialized parasite are discussed considering that Phallusia nigra has been introduced worldwide, in tropical and sub-tropical ecosystems, where it has the potential of becoming invasive.

Two New Tryptamine Derivatives, Leptoclinidamide and (--Leptoclinidamine B, from an Indonesian Ascidian Leptoclinides dubius

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Michio Namikoshi

2012-02-01

Full Text Available Two new tryptamine-derived alkaloids, named as leptoclinidamide (1 and (--leptoclinidamine B (2, were isolated from an Indonesian ascidian Leptoclinides dubius together with C2-α-D-mannosylpyranosyl-L-tryptophan (3. The structure of 1 was assigned on the basis of spectroscopic data for 1 and its N-acetyl derivative (4. Compound 1 was an amide of tryptamine with two β-alanine units. Although the planar structure of 2 is identical to that of the known compound (+-leptoclinidamine B (5, compound 2 was determined to be the enantiomer of 5 based on amino acid analysis using HPLC methods. Compounds 1 to 4 were evaluated for cytotoxicity against two human cancer cell lines, HCT-15 (colon and Jurkat (T-cell lymphoma cells, but none of the compounds showed activity.

Direct activation of a notochord cis-regulatory module by Brachyury and FoxA in the ascidian Ciona intestinalis.

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Passamaneck, Yale J; Katikala, Lavanya; Perrone, Lorena; Dunn, Matthew P; Oda-Ishii, Izumi; Di Gregorio, Anna

2009-11-01

The notochord is a defining feature of the chordate body plan. Experiments in ascidian, frog and mouse embryos have shown that co-expression of Brachyury and FoxA class transcription factors is required for notochord development. However, studies on the cis-regulatory sequences mediating the synergistic effects of these transcription factors are complicated by the limited knowledge of notochord genes and cis-regulatory modules (CRMs) that are directly targeted by both. We have identified an easily testable model for such investigations in a 155-bp notochord-specific CRM from the ascidian Ciona intestinalis. This CRM contains functional binding sites for both Ciona Brachyury (Ci-Bra) and FoxA (Ci-FoxA-a). By combining point mutation analysis and misexpression experiments, we demonstrate that binding of both transcription factors to this CRM is necessary and sufficient to activate transcription. To gain insights into the cis-regulatory criteria controlling its activity, we investigated the organization of the transcription factor binding sites within the 155-bp CRM. The 155-bp sequence contains two Ci-Bra binding sites with identical core sequences but opposite orientations, only one of which is required for enhancer activity. Changes in both orientation and spacing of these sites substantially affect the activity of the CRM, as clusters of identical sites found in the Ciona genome with different arrangements are unable to activate transcription in notochord cells. This work presents the first evidence of a synergistic interaction between Brachyury and FoxA in the activation of an individual notochord CRM, and highlights the importance of transcription factor binding site arrangement for its function.

Vascular budding in Symplegma brakenhielmi and the evolution of coloniality in styelid ascidians.

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Gutierrez, Stefania; Brown, Federico D

2017-03-15

Individuals of colonial animals (e.g. zooids) are in continuous turnover. In ascidians colonial or solitary species have evolved by convergence multiple times. Colonial Botryllus and Botrylloides are well-studied genera that exhibit colony-wide developmental mechanisms that regulate synchronous and orchestrated cycles of budding and turnover of zooids. The origins of modular developmental mechanisms that facilitated the evolution of coloniality in this group remain unclear. To reconstruct ancestral states of coloniality we studied Symplegma brakenhielmi, a sister taxon of the botryllids. S. brakenhielmi zooids are embedded in a common tunic and present a similar vascular system as the botrylloides, however development and turnover of zooids occurs asynchronously and in a more independent manner. We generated a table of common stages of budding in Symplegma and Botryllus for comparative studies of asexual development. We tested dependent processes of budding among individuals of the colony by systemic bud or zooid removals. Although our results showed a higher degree of independence in bud development in S. brakenhielmi, we found a subtle colony-wide regulatory mechanism of modular development, i.e. new buds expedited development after the removal of all buds in the colony. Next, we characterized external morphology, ultrastructure, and abundance of circulatory blood cells in the vascular system of S. brakenhielmi. Macrophage-like cells (MLCs) are involved in zooid resorption and turnover. Proportions of MLCs in the blood of S. brakenhielmi corresponded to the peak of occurrence of this cell type during the budding cycle of B. schlosseri. We found several new blood cell types in S. brakenhielmi, including two cell types that resemble circulatory progenitor stem cells of other botryllid colonial ascidians. These cells showed features of undifferentiated cells and expressed mitotic marker Phospho-histone H3. Comparative studies of S. brakenhielmi and B. schlosseri

Origin of the Henze solution/precipitate from morula cells of the blood of the ascidian Phallusia mammillata

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Nette, Geoffrey; Scippa, S.; de Vincentiis, Mario

The "Henze solution", derived originally from the aqueous extraction of pelleted whole blood from the ascidian Phallusia mammillata, was examined using spectral studies. The aqueous extraction of fractionated blood cells including compartment cells, signet ring cells, and morula cells obtained using cell separation techniques were also examined. It was found that this Henze solution, and the Henze precipitate itself derived from this solution, emanated solely from the morula cells. Furthermore, it was found that this solution is formed independently of the vanadium metal ions otherwise associated with the vanadocytes. Observation of the Henze precipitate by light microscopy shows that this material partially forms crystallites or microglasses.

Potential speciation of morphotypes in the photosymbiotic ascidian Didemnum molle in the Ryukyu Archipelago, Japan

Science.gov (United States)

Hirose, M.; Yokobori, S.; Hirose, E.

2009-03-01

Four morphotypes are recognized in the photosymbiotic ascidian Didemnum molle in the Ryukyu Archipelago: three color morphs (white, dark gray, and brown) of small-type colonies and one large-type colony (white with gray patches). The genetic variation among these four morphotypes was investigated by constructing phylogenetic trees based on a 401-bp fragment of the cytochrome oxidase subunit I (COI) gene of 29 specimens collected from five islands (Okinawajima, Sesokojima, Ikeijima, Kumejima, and Ishigakijima). The results support the monophyly of the genus Didemnum and that of the four morphotypes of D. molle. Moreover, the phylogenetic trees discriminated four clades corresponding to each morphotype. The geographic differences of the sequences were much smaller than the differences among the morphotypes, suggesting that the four morphotypes in D. molle are discrete sibling species.

Protection from Oxidative Stress in Immunocytes of the Colonial Ascidian Botryllus schlosseri: Transcript Characterization and Expression Studies.

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Franchi, Nicola; Ballin, Francesca; Ballarin, Loriano

2017-02-01

Botryllus schlosseri is a cosmopolitan colonial ascidian that undergoes cyclical generation changes, or take-overs, during which adult zooids are resorbed and replaced by their buds. At take-over, adult tissues undergo diffuse apoptosis and effete cells are massively ingested by circulating phagocytes, with a consequent increase in oxygen consumption and in production of reactive oxygen species (ROS). The latter are responsible for the death of phagocytes involved in the clearance of apoptotic cells and corpses by phagocytosis-induced apoptosis. However, the majority of phagocytes and hemocytes do not die, even if they experience oxidative stress. This fact suggests the presence of detoxification mechanisms assuring their protection. To test this assumption, we searched for transcripts of genes involved in detoxification in the transcriptome of B. schlosseri. We identified and characterized transcripts for Cu/Zn superoxide dismutase (SOD), γ-glutamyl-cysteine ligase modulatory subunit (GCLM), glutathione synthase (GS), and two glutathione peroxidases (i.e., GPx3 and GPx5), all involved in protection from ROS. We also carried out a phylogenetic analysis of the putative amino acid sequences, confirming their similarity to their vertebrate counterparts, and studied the location of their mRNAs by in situ hybridization on hemocyte monolayers. We also analyzed gene transcription during the colonial blastogenetic cycle, which is the interval of time between one take-over and the next, by qRT-PCR. In addition, we investigated the effects of cadmium (Cd), an inducer of oxidative stress, on gene transcription. Our results indicated that i) antioxidant gene expression is modulated in the course of the blastogenetic cycle and upon exposure to Cd, and ii) hemocytes synthesize both enzymatic and nonenzymatic antioxidants, in line with the idea that they represent a major detoxification system for ascidians.

Anticancer effects of brominated indole alkaloid Eudistomin H from marine ascidian Eudistoma viride against cervical cancer cells (HeLa).

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Rajesh, Rajaian Pushpabai; Annappan, Murugan

2015-01-01

Marine invertebrates called ascidians are prolific producers of bioactive substances. The ascidian Eudistoma viride, distributed along the Southeast coast of India, was investigated for its in vitro cytotoxic activity against human cervical carcinoma (HeLa) cells by the MTT assay. The crude methanolic extract of E. viride, with an IC50 of 53 μg/ml, was dose-dependently cytotoxic. It was more potent at 100 μg/ml than cyclohexamide (1 μg/ml), reducing cell viability to 9.2%. Among nine fractions separated by chromatography, ECF-8 exhibited prominent cytoxic activity at 10 μg/ml. The HPLC fraction EHF-21 of ECF-8 was remarkably dose- and time-dependently cytotoxic, with 39.8% viable cells at 1 μg/ml compared to 51% in cyclohexamide-treated cells at the same concentration; the IC50 was 0.49 μg/ml. Hoechst staining of HeLa cells treated with EHF-21 at 0.5 μg/ml revealed apoptotic events such an cell shrinkage, membrane blebbing, chromatin condensation and formation of apoptotic bodies. Cell size and granularity study showed changes in light scatter, indicating the characteristic feature of cells dying by apoptosis. The cell-cycle analysis of HeLa cells treated with fraction EHF-21 at 1 μg/ml showed the marked arrest of cells in G0/G1, S and G2/M phases and an increase in the sub G0/G1 population indicated an increase in the apoptotic cell population. The statistical analysis of the sub-G1 region showed a dose-dependent induction of apoptosis. DNA fragmentation was also observed in HeLa cells treated with EHF-21. The active EHF-21 fraction, a brominated indole alkaloid Eudistomin H, led to apoptotic death of HeLa cells. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

HSQC-TOCSY Fingerprinting-Directed Discovery of Antiplasmodial Polyketides from the Marine Ascidian-Derived Streptomyces sp. (USC-16018).

Science.gov (United States)

Buedenbender, Larissa; Robertson, Luke P; Lucantoni, Leonardo; Avery, Vicky M; Kurtböke, D İpek; Carroll, Anthony R

2018-05-30

Chemical investigations on the fermentation extract obtained from an ascidian-derived Streptomyces sp. (USC-16018) yielded a new ansamycin polyketide, herbimycin G ( 1 ), as well as a known macrocyclic polyketide, elaiophylin ( 2 ), and four known diketopiperazines ( 3 ⁻ 6 ). The structures of the compounds were elucidated based on 1D/2D NMR and MS data. The absolute configuration of 1 was established by comparison of experimental and predicted electronic circular dichroism (ECD) data. Antiplasmodial activities were tested for the natural products against chloroquine sensitive (3D7) and chloroquine resistant (Dd2) Plasmodium falciparum strains; the two polyketides ( 1 ⁻ 2 ) demonstrated an inhibition of >75% against both parasite strains and while 2 was highly cytotoxic, herbimycin G ( 1 ) showed no cytotoxicity and good predicted water solubility.

An ultraviolet-sensitive maternal mRNA encoding a cytoskeletal protein may be involved in axis formation in the ascidian embryo

International Nuclear Information System (INIS)

Jeffery, W.R.

1990-01-01

Ultraviolet (uv) irradiation of the vegetal hemisphere of fertilized eggs during ooplasmic segregation inhibits subsequent gastrulation and axis formation in ascidian embryos. The molecular basis of this phenomenon was investigated in by comparing in vivo protein synthesis and in vitro mRNA translation in normal and uv-irradiated embryos of the ascidian Styela clava. Analysis of protein synthesis by [35S]methionine incorporation, two-dimensional (2D) gel electrophoresis, and autoradiography showed that only 21 of 433 labeled polypeptides were missing or decreased in labeling intensity in uv-irradiated embryos. The most prominent of these was a 30,000 molecular weight (pI 6.0) polypeptide (p30). Extraction of gastrulae with the nonionic detergent Triton X-100 showed that p30 is retained in the detergent insoluble residue, suggesting that it is associated with the cytoskeleton. Several lines of evidence suggest that p30 may be involved in axis formation. First, p30 labeling peaks during gastrulation, when the embryonic axis is being established. Second, axis formation and p30 labeling are abolished by the same threshold uv dose, which is distinct from that required to inactivate muscle cell development. Third, the uv sensitivity period for abolishing p30 labeling and axis formation are both restricted to ooplasmic segregation. In vitro translation of egg RNA followed by 2D gel electrophoresis and autoradiography of the protein products showed that p30 is encoded by a maternal mRNA. The translation of p30 mRNA was abolished by uv irradiation of fertilized eggs during ooplasmic segregation suggesting that this message is a uv-sensitive target. The results are consistent with the hypothesis that uv irradiation blocks gastrulation and axis formation by inhibiting the translation of maternal mRNA localized in the vegetal hemisphere of the fertilized egg

Global phylogeography of the widely introduced North West Pacific ascidian Styela clava.

Science.gov (United States)

Goldstien, Sharyn J; Dupont, Lise; Viard, Frédérique; Hallas, Paul J; Nishikawa, Teruaki; Schiel, David R; Gemmell, Neil J; Bishop, John D D

2011-02-22

The solitary ascidian Styela clava Herdman, 1882 is considered to be native to Japan, Korea, northern China and the Russian Federation in the NW Pacific, but it has spread globally over the last 80 years and is now established as an introduced species on the east and west coasts of North America, Europe, Australia and New Zealand. In eastern Canada it reaches sufficient density to be a serious pest to aquaculture concerns. We sequenced a fragment of the cytochrome oxidase subunit I mitochondrial gene (COI) from a total of 554 individuals to examine the genetic relationships of 20 S. clava populations sampled throughout the introduced and native ranges, in order to investigate invasive population characteristics. The data presented here show a moderate level of genetic diversity throughout the northern hemisphere. The southern hemisphere (particularly New Zealand) displays a greater amount of haplotype and nucleotide diversity in comparison. This species, like many other invasive species, shows a range of genetic diversities among introduced populations independent of the age of incursion. The successful establishment of this species appears to be associated with multiple incursions in many locations, while other locations appear to have experienced rapid expansion from a potentially small population with reduced genetic diversity. These contrasting patterns create difficulties when attempting to manage and mitigate a species that continues to spread among ports and marinas around the world.

Adverse Effect of Antifouling Compounds on the Reproductive Mechanisms of the Ascidian Ciona intestinalis

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Alessandra Gallo

2013-09-01

Full Text Available Fertilization and embryo development that occur in sea water are sensitive to xenobiotics from anthropogenic sources. In this work, we evaluated the influence of two antifouling biocides, tributyltin (TBT and diuron, on the reproductive mechanisms of the marine invertebrate Ciona intestinalis. By using electrophysiological techniques, we examined the impact of these compounds on the electrical properties of the mature oocytes and of events occurring at fertilization. With different toxicity assays, we studied the effect of the two biocides on the gametes by evaluating fertilization rate and embryo development. Results show that sodium (Na+ currents were significantly reduced by either of the two biocides, whereas conductance was significantly increased. The fertilization current frequency and amplitude, fertilization rate and larval development were affected only by TBT. This study suggests that: (i the two biocides affect either the electrical properties of the oocyte plasma membrane and the reproductive success representing a risk factor for the survival of the species exposed to environmental pollution; (ii the ascidian Ciona intestinalis may represent a good model organism to test toxicity of marine pollutants. Possible mechanisms of action of the two biocides are discussed.

Adverse Effect of Antifouling Compounds on the Reproductive Mechanisms of the Ascidian Ciona intestinalis

Science.gov (United States)

Gallo, Alessandra; Tosti, Elisabetta

2013-01-01

Fertilization and embryo development that occur in sea water are sensitive to xenobiotics from anthropogenic sources. In this work, we evaluated the influence of two antifouling biocides, tributyltin (TBT) and diuron, on the reproductive mechanisms of the marine invertebrate Ciona intestinalis. By using electrophysiological techniques, we examined the impact of these compounds on the electrical properties of the mature oocytes and of events occurring at fertilization. With different toxicity assays, we studied the effect of the two biocides on the gametes by evaluating fertilization rate and embryo development. Results show that sodium (Na+) currents were significantly reduced by either of the two biocides, whereas conductance was significantly increased. The fertilization current frequency and amplitude, fertilization rate and larval development were affected only by TBT. This study suggests that: (i) the two biocides affect either the electrical properties of the oocyte plasma membrane and the reproductive success representing a risk factor for the survival of the species exposed to environmental pollution; (ii) the ascidian Ciona intestinalis may represent a good model organism to test toxicity of marine pollutants. Possible mechanisms of action of the two biocides are discussed. PMID:24065165

Adverse effect of antifouling compounds on the reproductive mechanisms of the ascidian Ciona intestinalis.

Science.gov (United States)

Gallo, Alessandra; Tosti, Elisabetta

2013-09-20

Fertilization and embryo development that occur in sea water are sensitive to xenobiotics from anthropogenic sources. In this work, we evaluated the influence of two antifouling biocides, tributyltin (TBT) and diuron, on the reproductive mechanisms of the marine invertebrate Ciona intestinalis. By using electrophysiological techniques, we examined the impact of these compounds on the electrical properties of the mature oocytes and of events occurring at fertilization. With different toxicity assays, we studied the effect of the two biocides on the gametes by evaluating fertilization rate and embryo development. Results show that sodium (Na⁺) currents were significantly reduced by either of the two biocides, whereas conductance was significantly increased. The fertilization current frequency and amplitude, fertilization rate and larval development were affected only by TBT. This study suggests that: (i) the two biocides affect either the electrical properties of the oocyte plasma membrane and the reproductive success representing a risk factor for the survival of the species exposed to environmental pollution; (ii) the ascidian Ciona intestinalis may represent a good model organism to test toxicity of marine pollutants. Possible mechanisms of action of the two biocides are discussed.

Cyclic Hexapeptide Dimers, Antatollamides A and B, from the Ascidian Didemnum molle. A Tryptophan-Derived Auxiliary for l- and d-Amino Acid Assignments.

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Salib, Mariam N; Molinski, Tadeusz F

2017-10-06

Two dimerized cyclic hexapeptides, antatollamides A (1) and B (2), were isolated from the colonial ascidian Didemnum molle collected in Pohnpei. The amino acid compositions and sequences were determined by interpretation of MS and 1D and 2D NMR data. Raney Ni reduction of antatollamide A cleaved the dimer to the corresponding monomeric cyclic hexapeptide with replacement of Cys by Ala. The amino acid configuration of 1 was established, after total hydrolysis, by derivatization with a new chiral reagent, (5-fluoro-2,4-dinitrophenyl)-N α -l-tryptophanamide (FDTA), prepared from l-Trp, followed by LCMS analysis; all amino acids were found to be l-configured except for d-Ala.

Distal Regeneration Involves the Age Dependent Activity of Branchial Sac Stem Cells in the Ascidian Ciona intestinalis.

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Jeffery, William R

2015-02-01

Tunicates have high capacities for regeneration but the underlying mechanisms and their relationship to life cycle progression are not well understood. Here we investigate the regeneration of distal structures in the ascidian tunicate Ciona intestinalis . Analysis of regenerative potential along the proximal-distal body axis indicated that distal organs, such as the siphons, their pigmented sensory organs, and the neural complex, could only be replaced from body fragments containing the branchial sac. Distal regeneration involves the formation of a blastema composed of cells that undergo cell proliferation prior to differentiation and cells that differentiate without cell proliferation. Both cell types originate in the branchial sac and appear in the blastema at different times after distal injury. Whereas the branchial sac stem cells are present in young animals, they are depleted in old animals that have lost their regeneration capacity. Thus Ciona adults contain a population of age-related stem cells located in the branchial sac that are a source of precursors for distal body regeneration.

The Sexual and Mating System of the Shrimp Odontonia katoi (Palaemonidae, Pontoniinae), a Symbiotic Guest of the Ascidian Polycarpa aurata in the Coral Triangle

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Baeza, J. Antonio; Hemphill, Carrie A.; Ritson-Williams, Raphael

2015-01-01

Theory predicts that monogamy is adaptive in symbiotic crustaceans inhabiting relatively small and morphologically simple hosts in tropical environments where predation risk away from hosts is high. We tested this prediction in the shrimp Odontonia katoi, which inhabits the atrial chamber of the ascidian Polycarpa aurata in the Coral Triangle. Preliminary observations in O. katoi indicated that males were smaller than females, which is suggestive of sex change (protandry) in some symbiotic organisms. Thus, we first investigated the sexual system of O. katoi to determine if this shrimp was sequentially hermaphroditic. Morphological identification and size frequency distributions indicated that the population comprised males that, on average, were smaller than females. Gonad dissections demonstrated the absence of transitional individuals. Thus, O. katoi is a gonochoric species with reverse sexual dimorphism. The population distribution of O. katoi in its ascidian host did not differ significantly from a random distribution and shrimps inhabiting the same host individual as pairs were found with a frequency similar to that expected by chance alone. This is in contrast to that reported for other socially monogamous crustaceans in which pairs of heterosexual conspecifics are found in host individuals more frequently than expected by chance alone. Thus, the available information argues against monogamy in O. katoi. Furthermore, that a high frequency of solitary females were found brooding embryos and that the sex ratio was skewed toward females suggests that males might be roaming among hosts in search of receptive females in O. katoi. Symbiotic crustaceans can be used as a model system to understand the adaptive value of sexual and mating systems in marine invertebrates. PMID:25799577

Measurement of refractive indices of tunicates' tunics: light reflection of the transparent integuments in an ascidian Rhopalaea sp. and a salp Thetys vagina.

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Kakiuchida, Hiroshi; Sakai, Daisuke; Nishikawa, Jun; Hirose, Euichi

2017-01-01

Tunic is a cellulosic, integumentary matrix found in tunicates (Subphylum Tunicata or Urochordata). The tunics of some ascidian species and pelagic tunicates, such as salps, are nearly transparent, which is useful in predator avoidance. Transparent materials can be detected visually using light reflected from their surfaces, with the different refractive indices between two media, i.e., tunic and seawater, being the measure of reflectance. A larger difference in refractive indices thus provides a larger measure of reflectance. We measured the refractive indices of the transparent tunic of Thetys vagina (salp: Thaliacea) and Rhopalae a sp. (ascidian: Ascidiacea) using an Abbe refractometer and an ellipsometer to estimate the light reflection at the tunic surface and evaluate the anti-reflection effect of the nipple array structure on the tunic surface of T. vagina . At D-line light (λ = 589 nm), the refractive indices of the tunics were 0.002-0.004 greater than seawater in the measurements by Abbe refractometer, and 0.02-0.03 greater than seawater in the measurements by ellipsometer. The refractive indices of tunics were slightly higher than that of seawater. According to the simulation of light reflection based on rigorous coupled wave analysis (RCWA), light at a large angle of incidence will be completely reflected from a surface when its refractive indices are smaller than seawater. Therefore, the refractive index of integument is important for enabling transparent organisms to remain invisible in the water column. In order to minimize reflectance, the refractive index should be similar to, but never smaller than, that of the surrounding seawater. The simulation also indicated that the presence or absence of a nipple array does not cause significant difference in reflectance on the surface. The nipple array on the tunic of the diurnal salp may have another function, such as bubble repellence, other than anti-reflection.

Blood circulation in the ascidian tunicate Corella inflata (Corellidae)

Science.gov (United States)

2016-01-01

The body of the ascidian tunicate Corella inflata is relatively transparent. Thus, the circulatory system can be visualized by injecting high molecular weight fluorescein labeled dextran into the heart or the large vessels at the ends of the heart without surgery to remove the body wall. In addition, after staining with neutral red, the movement of blood cells can be easily followed to further characterize the circulatory system. The heart is two gently curved concentric tubes extending across the width of the animal. The inner myocardial tube has a partial constriction approximately in the middle. As in other tunicates, the heart is peristaltic and periodically reverses direction. During the branchial phase blood leaves the anterior end of the heart by two asymmetric vessels that connect to the two sides of the branchial basket. Blood then flows in both transverse directions through a complex system of ducts in the basket into large ventral and dorsal vessels which carry blood back to the visceral organs in the posterior of the animal. During the visceral phase blood leaves the posterior end of the heart in two vessels that repeatedly bifurcate and fan into the stomach and gonads. Blood velocity, determined by following individual cells in video frames, is high and pulsatory near the heart. A double peak in velocity at the maximum may be due to the constriction in the middle of the heart tube. Blood velocity progressively decreases with distance from the heart. In peripheral regions with vessels of small diameter blood cells frequently collide with vessel walls and cell motion is erratic. The estimated volume of blood flow during each directional phase is greater than the total volume of the animal. Circulating blood cells are confined to vessels or ducts in the visible parts of the animal and retention of high molecular weight dextran in the vessels is comparable to that seen in vertebrates. These are characteristics of a closed circulatory system. PMID:27994977

Redescription of the deep-sea colonial ascidian Synoicum molle (Herdman, 1886: first record since its original finding during the Challenger Expedition

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Tamara Maggioni

2016-10-01

Full Text Available The colonial ascidian Synoicum molle (Herdman, 1886 was recorded for the first time after its original description. The slope area where S. molle was discovered during the Challenger Expedition (1872-1876, located at the mouth off Río de La Plata (Argentine Sea, still remains highly underexplored. During a series of deep-sea prospections along the SW Atlantic (A.R.A. Puerto Deseado, August 2012, 7 colonies of S. molle were collected few km from the type locality. The finding permitted to perform, for the first time, a complete morphological description of this species. The proper identification of marine species, especially deep-sea organisms, has implications for the general knowledge of biodiversity, a necessary tool for the conservation and study of ecosystem benefits that marine environments provide.

Simulated overfishing and natural eutrophication promote the relative success of a non-indigenous ascidian in coral reefs at the Pacific coast of Costa Rica

KAUST Repository

Roth, Florian; Stuhldreier, Ines; Sá nchez-Noguera, Celeste; Carvalho, Susana; Wild, Christian

2017-01-01

Colonial ascidians of the genus Didemnum are common fouling organisms and are typically associated with degraded ecosystems and anthropogenic structures installed in the sea. In this study, however, the non-indigenous ascidian Didemnum cf. perlucidum Monniot F., 1983 was discovered in coral reef environments on the Pacific coast of Costa Rica. Its role in the succession of a benthic community and the impact on biogeochemical features (i.e. reef cementation) was assessed by deploying terracotta settlement tiles on the reef for 24 weeks. Predator exclusion in experimental plots and naturally elevated nutrient concentrations during seasonal coastal upwelling gave insights on how settlers of D. cf. perlucidum succeed under projected environmental change. Exclusion of larger predators and grazers caused an increase of D. cf. perlucidum coverage on tiles from 7 to > 80%. Due to its rapid proliferation, D. cf. perlucidum grew over calcifying reef organisms, such as barnacles, polychaetes, and crustose algae, and significantly decreased the accumulation of inorganic carbon on the settlement tiles by one order of magnitude (4.6 to 0.4 mg C cm). The combination of reduced predation and eutrophication revealed negative synergistic effects on the accumulation of inorganic carbon. The opportunistic reaction of D. cf. perlucidum to environmental changes was further evident by 2-fold increased growth rates that were positively correlated (r = 0.89) to seawater particulate organic matter (POM) concentration during coastal upwelling. These results suggest that D. cf. perlucidum is a strong spatial competitor in Eastern Tropical Pacific coral reefs that face changing environmental conditions, e.g. overfishing and eutrophication. The effects of this species on disturbed benthic communities, but also its potential role as a habitat modifier, is likely significant. Thus, a continuous monitoring of D. cf. perlucidum is recommended to better understand their effects on post

Simulated overfishing and natural eutrophication promote the relative success of a non-indigenous ascidian in coral reefs at the Pacific coast of Costa Rica

KAUST Repository

Roth, Florian

2017-11-20

Colonial ascidians of the genus Didemnum are common fouling organisms and are typically associated with degraded ecosystems and anthropogenic structures installed in the sea. In this study, however, the non-indigenous ascidian Didemnum cf. perlucidum Monniot F., 1983 was discovered in coral reef environments on the Pacific coast of Costa Rica. Its role in the succession of a benthic community and the impact on biogeochemical features (i.e. reef cementation) was assessed by deploying terracotta settlement tiles on the reef for 24 weeks. Predator exclusion in experimental plots and naturally elevated nutrient concentrations during seasonal coastal upwelling gave insights on how settlers of D. cf. perlucidum succeed under projected environmental change. Exclusion of larger predators and grazers caused an increase of D. cf. perlucidum coverage on tiles from 7 to > 80%. Due to its rapid proliferation, D. cf. perlucidum grew over calcifying reef organisms, such as barnacles, polychaetes, and crustose algae, and significantly decreased the accumulation of inorganic carbon on the settlement tiles by one order of magnitude (4.6 to 0.4 mg C cm). The combination of reduced predation and eutrophication revealed negative synergistic effects on the accumulation of inorganic carbon. The opportunistic reaction of D. cf. perlucidum to environmental changes was further evident by 2-fold increased growth rates that were positively correlated (r = 0.89) to seawater particulate organic matter (POM) concentration during coastal upwelling. These results suggest that D. cf. perlucidum is a strong spatial competitor in Eastern Tropical Pacific coral reefs that face changing environmental conditions, e.g. overfishing and eutrophication. The effects of this species on disturbed benthic communities, but also its potential role as a habitat modifier, is likely significant. Thus, a continuous monitoring of D. cf. perlucidum is recommended to better understand their effects on post

Distal regeneration involves the age dependent activity of branchial sac stem cells in the ascidian Ciona intestinalis

Science.gov (United States)

2014-01-01

Abstract Tunicates have high capacities for regeneration but the underlying mechanisms and their relationship to life cycle progression are not well understood. Here we investigate the regeneration of distal structures in the ascidian tunicate Ciona intestinalis. Analysis of regenerative potential along the proximal−distal body axis indicated that distal organs, such as the siphons, their pigmented sensory organs, and the neural complex, could only be replaced from body fragments containing the branchial sac. Distal regeneration involves the formation of a blastema composed of cells that undergo cell proliferation prior to differentiation and cells that differentiate without cell proliferation. Both cell types originate in the branchial sac and appear in the blastema at different times after distal injury. Whereas the branchial sac stem cells are present in young animals, they are depleted in old animals that have lost their regeneration capacity. Thus Ciona adults contain a population of age‐related stem cells located in the branchial sac that are a source of precursors for distal body regeneration. PMID:25893097

Hematological Analysis of the Ascidian Botrylloides leachii (Savigny, 1816) During Whole-Body Regeneration.

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Blanchoud, Simon; Zondag, Lisa; Lamare, Miles D; Wilson, Megan J

2017-06-01

Whole-body regeneration (WBR)-the formation of an entire adult from only a small fragment of its own tissue-is extremely rare among chordates. Exceptionally, in the colonial ascidian Botrylloides leachii (Savigny, 1816) a fully functional adult is formed from their common vascular system after ablation of all adults from the colony in just 10 d, thanks to their high blastogenetic potential. While previous studies have identified key genetic markers and morphological changes, no study has yet focused on the hematological aspects of regeneration despite the major involvement of the remaining vascular system and the contained hemocytes in this process. To dissect this process, we analyzed colony blood flow patterns using time-lapse microscopy to obtain a quantitative description of the velocity, reversal pattern, and average distance traveled by hemocytes. We also observed that flows present during regeneration are powered by temporally and spatially synchronized contractions of the terminal ampullae. In addition, we revised previous studies of B. leachii hematology as well as asexual development using histological sectioning and compared the role played by hemocytes during WBR. We found that regeneration starts with a rapid healing response characterized by hemocyte aggregation and infiltration of immunocytes, followed by increased activity of hemoblasts, recruitment of macrophage-like cells for clearing the tissues of debris, and their subsequent disappearance from the circulation concomitant with the maturation of a single regenerated adult. Overall, we provide a detailed account of the hematological properties of regenerating B. leachii colonies, providing novel lines of inquiry toward the decipherment of regeneration in chordates.

Cytotoxicity of actinomycetes associated with the ascidian Eudistoma vannamei (Millar, 1977, endemic of northeastern coast of Brazil

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Paula C Jimenez

2013-04-01

Full Text Available Previous studies demonstrated that the crude extract of the ascidian Eudistoma vannamei, endemic from northeasttern Brazil, strongly hinders growth of tumor cells in vitro by inducing apoptosis due to tryptophan derivatives, which are commonly found in bacteria. This study presents a bioactivity-guided screening among actinomycetes, associated with E. vannamei, aiming at recognizing active principles with biological relevance. Twenty strains of actinomycetes, designated as EVA 0101 through 0120, were isolated from colonies of E. vannamei among which 11 were selected for cytotoxicity evaluation. The extracts from EVA 0102, 0103, 0106, 0109 and 0113 were the most active, and were further studied for IC50 determination and chemical analysis by ¹H NMR. IC50 values obtained ranged from 3.62 µg mL-1 (for EVA 0109 in leukemia cells to 84.65 µg/mL (for EVA 0106 in melanoma cells. All active extracts exhibited the same TLC and spectroscopic profiles, suggesting the presence of quinones and other related secondary metabolites. Furthermore, these strains were identified and compared based on their respective 16S rRNA sequences. The results herein identified the five strains as Micromonospora spp. while phylogenetic analysis suggests that they are possibly two different Micromonospora species producing the cytotoxic compounds.

Evidence of a Native Northwest Atlantic COI Haplotype Clade in the Cryptogenic Colonial Ascidian Botryllus schlosseri.

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Yund, Philip O; Collins, Catherine; Johnson, Sheri L

2015-06-01

The colonial ascidian Botryllus schlosseri should be considered cryptogenic (i.e., not definitively classified as either native or introduced) in the Northwest Atlantic. Although all the evidence is quite circumstantial, over the last 15 years most research groups have accepted the scenario of human-mediated dispersal and classified B. schlosseri as introduced; others have continued to consider it native or cryptogenic. We address the invasion status of this species by adding 174 sequences to the growing worldwide database for the mitochondrial gene cytochrome c oxidase subunit I (COI) and analyzing 1077 sequences to compare genetic diversity of one clade of haplotypes in the Northwest Atlantic with two hypothesized source regions (the Northeast Atlantic and Mediterranean). Our results lead us to reject the prevailing view of the directionality of transport across the Atlantic. We argue that the genetic diversity patterns at COI are far more consistent with the existence of at least one haplotype clade in the Northwest Atlantic (and possibly a second) that substantially pre-dates human colonization from Europe, with this native North American clade subsequently introduced to three sites in Northeast Atlantic and Mediterranean waters. However, we agree with past researchers that some sites in the Northwest Atlantic have more recently been invaded by alien haplotypes, so that some populations are currently composed of a mixture of native and invader haplotypes. © 2015 Marine Biological Laboratory.

Enzyme domain affects the movement of the voltage sensor in ascidian and zebrafish voltage-sensing phosphatases.

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Hossain, Md Israil; Iwasaki, Hirohide; Okochi, Yoshifumi; Chahine, Mohamed; Higashijima, Shinichi; Nagayama, Kuniaki; Okamura, Yasushi

2008-06-27

The ascidian voltage-sensing phosphatase (Ci-VSP) consists of the voltage sensor domain (VSD) and a cytoplasmic phosphatase region that has significant homology to the phosphatase and tensin homolog deleted on chromosome TEN (PTEN). The phosphatase activity of Ci-VSP is modified by the conformational change of the VSD. In many proteins, two protein modules are bidirectionally coupled, but it is unknown whether the phosphatase domain could affect the movement of the VSD in VSP. We addressed this issue by whole-cell patch recording of gating currents from a teleost VSP (Dr-VSP) cloned from Danio rerio expressed in tsA201 cells. Replacement of a critical cysteine residue, in the phosphatase active center of Dr-VSP, by serine sharpened both ON- and OFF-gating currents. Similar changes were produced by treatment with phosphatase inhibitors, pervanadate and orthovanadate, that constitutively bind to cysteine in the active catalytic center of phosphatases. The distinct kinetics of gating currents dependent on enzyme activity were not because of altered phosphatidylinositol 4,5-bisphosphate levels, because the kinetics of gating current did not change by depletion of phosphatidylinositol 4,5-bisphosphate, as reported by coexpressed KCNQ2/3 channels. These results indicate that the movement of the VSD is influenced by the enzymatic state of the cytoplasmic domain, providing an important clue for understanding mechanisms of coupling between the VSD and its effector.

A one-dimensional model of PCP signaling: polarized cell behavior in the notochord of the ascidian Ciona.

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Kourakis, Matthew J; Reeves, Wendy; Newman-Smith, Erin; Maury, Benoit; Abdul-Wajid, Sarah; Smith, William C

2014-11-01

Despite its importance in development and physiology the planar cell polarity (PCP) pathway remains one of the most enigmatic signaling mechanisms. The notochord of the ascidian Ciona provides a unique model for investigating the PCP pathway. Interestingly, the notochord appears to be the only embryonic structure in Ciona activating the PCP pathway. Moreover, the Ciona notochord as a single-file array of forty polarized cells is a uniquely tractable system for the study of polarization dynamics and the transmission of the PCP pathway. Here, we test models for propagation of a polarizing signal, interrogating temporal, spatial and signaling requirements. A simple cell-cell relay cascading through the entire length of the notochord is not supported; instead a more complex mechanism is revealed, with interactions influencing polarity between neighboring cells, but not distant ones. Mechanisms coordinating notochord-wide polarity remain elusive, but appear to entrain general (i.e., global) polarity even while local interactions remain important. However, this global polarizer does not appear to act as a localized, spatially-restricted determinant. Coordination of polarity along the long axis of the notochord requires the PCP pathway, a role we demonstrate is temporally distinct from this pathway's earlier role in convergent extension and intercalation. We also reveal polarity in the notochord to be dynamic: a cell's polarity state can be changed and then restored, underscoring the Ciona notochord's amenability for in vivo studies of PCP. Copyright © 2014 Elsevier Inc. All rights reserved.

Germ cell regeneration-mediated, enhanced mutagenesis in the ascidian Ciona intestinalis reveals flexible germ cell formation from different somatic cells.

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Yoshida, Keita; Hozumi, Akiko; Treen, Nicholas; Sakuma, Tetsushi; Yamamoto, Takashi; Shirae-Kurabayashi, Maki; Sasakura, Yasunori

2017-03-15

The ascidian Ciona intestinalis has a high regeneration capacity that enables the regeneration of artificially removed primordial germ cells (PGCs) from somatic cells. We utilized PGC regeneration to establish efficient methods of germ line mutagenesis with transcription activator-like effector nucleases (TALENs). When PGCs were artificially removed from animals in which a TALEN pair was expressed, somatic cells harboring mutations in the target gene were converted into germ cells, this germ cell population exhibited higher mutation rates than animals not subjected to PGC removal. PGC regeneration enables us to use TALEN expression vectors of specific somatic tissues for germ cell mutagenesis. Unexpectedly, cis elements for epidermis, neural tissue and muscle could be used for germ cell mutagenesis, indicating there are multiple sources of regenerated PGCs, suggesting a flexibility of differentiated Ciona somatic cells to regain totipotency. Sperm and eggs of a single hermaphroditic, PGC regenerated animal typically have different mutations, suggesting they arise from different cells. PGCs can be generated from somatic cells even though the maternal PGCs are not removed, suggesting that the PGC regeneration is not solely an artificial event but could have an endogenous function in Ciona. This study provides a technical innovation in the genome-editing methods, including easy establishment of mutant lines. Moreover, this study suggests cellular mechanisms and the potential evolutionary significance of PGC regeneration in Ciona. Copyright © 2017 Elsevier Inc. All rights reserved.

Redundant mechanisms are involved in suppression of default cell fates during embryonic mesenchyme and notochord induction in ascidians.

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Kodama, Hitoshi; Miyata, Yoshimasa; Kuwajima, Mami; Izuchi, Ryoichi; Kobayashi, Ayumi; Gyoja, Fuki; Onuma, Takeshi A; Kumano, Gaku; Nishida, Hiroki

2016-08-01

During embryonic induction, the responding cells invoke an induced developmental program, whereas in the absence of an inducing signal, they assume a default uninduced cell fate. Suppression of the default fate during the inductive event is crucial for choice of the binary cell fate. In contrast to the mechanisms that promote an induced cell fate, those that suppress the default fate have been overlooked. Upon induction, intracellular signal transduction results in activation of genes encoding key transcription factors for induced tissue differentiation. It is elusive whether an induced key transcription factor has dual functions involving suppression of the default fates and promotion of the induced fate, or whether suppression of the default fate is independently regulated by other factors that are also downstream of the signaling cascade. We show that during ascidian embryonic induction, default fates were suppressed by multifold redundant mechanisms. The key transcription factor, Twist-related.a, which is required for mesenchyme differentiation, and another independent transcription factor, Lhx3, which is dispensable for mesenchyme differentiation, sequentially and redundantly suppress the default muscle fate in induced mesenchyme cells. Similarly in notochord induction, Brachyury, which is required for notochord differentiation, and other factors, Lhx3 and Mnx, are likely to suppress the default nerve cord fate redundantly. Lhx3 commonly suppresses the default fates in two kinds of induction. Mis-activation of the autonomously executed default program in induced cells is detrimental to choice of the binary cell fate. Multifold redundant mechanisms would be required for suppression of the default fate to be secure. Copyright © 2016 Elsevier Inc. All rights reserved.

Isolation and biological activities of secondary metabolites from the sponges monanchora aff. arbuscula, aplysina sp. petromica ciocalyptoides and topsentia ophiraphidies, from the ascidian didemnum ligulum and from the octocoral carijoa riisei

International Nuclear Information System (INIS)

Kossuga, Miriam H.; Lira, Simone P. de; Nascimento, Andrea M.; Gambardella, Maria Teresa P.; Berlinck, Roberto G.S.; Torres, Yohandra R.; Nascimento, Gislene G.F.; Pimenta, Eli F.; Silva, Marcio; Thiemann, Otavio H.; Oliva, Glaucius; Tempone, Andre G.; Melhem, Marcia S.C.; Souza, Ana O. de; Galetti, Fabio C.S.; Silva, Celio L.; Cavalcanti, Bruno; Pessoa, Claudia O.; Moraes, Manoel O.; Hajdu, Eduardo; Peixinho, Solange; Rocha, Rosana M.

2007-01-01

The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60. (author)

Natural products from the ascidian Botrylloides giganteum, from the sponges Verongula gigantea, Ircinia felix, Cliona delitrix and from the nudibranch Tambja eliora, from the Brazilian coastline

International Nuclear Information System (INIS)

Granato, Ana Claudia; Oliveira, Jaine H.H.L. de; Seleghim, Mirna H.R.; Berlinck, Roberto G.S.; Macedo, Mario L.; Ferreira, Antonio G.; Rocha, Rosana M. da; Hajdu, Eduardo; Peixinho, Solange; Pessoa, Claudia O.; Moraes, Manoel O.; Cavalcanti, Bruno C.

2005-01-01

Two new marine metabolites, 3Z, 6Z, 9Z-dodecatrien-1-ol (1) from the ascidian Botrylloides giganteum and 4H-pyran-2ol acetate from the sponge Ircinia felix (4) are herein reported. The known bromotyrosine compounds, 2-(3,5-dibromo-4-methoxyphenyl)-N,N,Ndimethylethanammonium (2) and 2,6-dibromo-4-(2-(trimethylammonium)ethyl)phenol (3), have been isolated from the sponge Verongula gigantea. Serotonin (5) is reported for the first time from the sponge Cliona delitrix, and tambjamines A (15) and D (16) isolated as their respective salts from the nudibranch Tambja eliora. Only tambjamine D presented cytotoxicity against CEM (IC 5 )0 12.2 μg/mL) and HL60 (IC 50 13.2 μg/mL) human leukemia cells, MCF-7 breast cancer cells (IC 50 13.2 μg/mL), colon HCT-8 cancer cells (IC 50 10.1 μg/mL) and murine melanoma B16 cancer cells (IC 50 6.7 μg/mL). (author)

Variation in the composition of corals, fishes, sponges, echinoderms, ascidians, molluscs, foraminifera and macroalgae across a pronounced in-to-offshore environmental gradient in the Jakarta Bay-Thousand Islands coral reef complex.

Science.gov (United States)

Cleary, D F R; Polónia, A R M; Renema, W; Hoeksema, B W; Rachello-Dolmen, P G; Moolenbeek, R G; Budiyanto, A; Yahmantoro; Tuti, Y; Giyanto; Draisma, S G A; Prud'homme van Reine, W F; Hariyanto, R; Gittenberger, A; Rikoh, M S; de Voogd, N J

2016-09-30

Substrate cover, water quality parameters and assemblages of corals, fishes, sponges, echinoderms, ascidians, molluscs, benthic foraminifera and macroalgae were sampled across a pronounced environmental gradient in the Jakarta Bay-Thousand Islands reef complex. Inshore sites mainly consisted of sand, rubble and turf algae with elevated temperature, dissolved oxygen, pH and chlorophyll concentrations and depauperate assemblages of all taxa. Live coral cover was very low inshore and mainly consisted of sparse massive coral heads and a few encrusting species. Faunal assemblages were more speciose and compositionally distinct mid- and offshore compared to inshore. There were, however, small-scale differences among taxa. Certain midshore sites, for example, housed assemblages resembling those typical of the inshore environment but this differed depending on the taxon. Substrate, water quality and spatial variables together explained from 31% (molluscs) to 72% (foraminifera) of the variation in composition. In general, satellite-derived parameters outperformed locally measured parameters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Expression of genes involved in oxidative stress response in colonies of the ascidian Botryllus schlosseri exposed to various environmental conditions

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Tasselli, Stefano; Ballin, Francesca; Franchi, Nicola; Fabbri, Elena; Ballarin, Loriano

2017-03-01

Environmental stress conditions are ultimately related to the induction of oxidative stress in organisms, as a consequence of an increased production of reactive oxygen species (ROS). This could be exploited to study sub-lethal effects induced by the environment in the organisms. In the present work, we evaluate the possibility to use the colonial ascidian Botryllus schlosseri as a bioindicator, to assess the environmental quality in the Lagoon of Venice. Three colony batches were immersed, for 22 days, at two sites (1 and 2) with different grades of hydrodynamics and anthropogenic impact and physico-chemical features of seawater; a control batch was kept in a large tank with continuous seawater flow at the Marine Station of the Department of Biology, University of Padova, in Chioggia (site 3). Seawater at site 2 had higher pH and temperature than site 1. Colonies were then retrieved, their mRNA was extracted and the level of transcription of genes involved in oxidative stress response (glutathione synthase, γ-glutamyl-cysteine ligase, modulatory subunit, two isoforms of glutathione peroxidases and Cu/Zn superoxide dismutase) was evaluated. In colonies from sites 1 and 2, most genes showed significantly increased transcriptional levels with respect to control values. Spectrophotometric analyses of colony homogenates revealed that the enzymatic activity of superoxide dismutase and catalase was higher in colonies from site 2 as compared to site 1, allowing us to speculate that colonies in site 2 were under higher stress level than those in site 1. Overall, we can conclude that B. schlosseri seems a good indicator of the ecological status of the Lagoon environment, within a range of pH and temperature in which colonies are used to live.

Regulation of the number of cell division rounds by tissue-specific transcription factors and Cdk inhibitor during ascidian embryogenesis.

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Mami Kuwajima

Full Text Available Mechanisms that regulate the number of cell division rounds during embryogenesis have remained largely elusive. To investigate this issue, we used the ascidian, which develops into a tadpole larva with a small number of cells. The embryonic cells divide 11.45 times on average from fertilization to hatching. The number of cell division rounds varies depending on embryonic lineages. Notochord and muscle consist of large postmitotic cells and stop dividing early in developing embryos. Here we show that conversion of mesenchyme to muscle cell fates by inhibition of inductive FGF signaling or mis-expression of a muscle-specific key transcription factor for muscle differentiation, Tbx6, changed the number of cell divisions in accordance with the altered fate. Tbx6 likely activates a putative mechanism to halt cell division at a specific stage. However, precocious expression of Tbx6 has no effect on progression of the developmental clock itself. Zygotic expression of a cyclin-dependent kinase inhibitor, CKI-b, is initiated in muscle and then in notochord precursors. CKI-b is possibly downstream of tissue-specific key transcription factors of notochord and muscle. In the two distinct muscle lineages, postmitotic muscle cells are generated after 9 and 8 rounds of cell division depending on lineage, but the final cell divisions occur at a similar developmental stage. CKI-b gene expression starts simultaneously in both muscle lineages at the 110-cell stage, suggesting that CKI-b protein accumulation halts cell division at a similar stage. The difference in the number of cell divisions would be due to the cumulative difference in cell cycle length. These results suggest that muscle cells do not count the number of cell division rounds, and that accumulation of CKI-b protein triggered by tissue-specific key transcription factors after cell fate determination might act as a kind of timer that measures elapsed time before cell division termination.

Reference gene selection for quantitative gene expression studies during biological invasions: A test on multiple genes and tissues in a model ascidian Ciona savignyi.

Science.gov (United States)

Huang, Xuena; Gao, Yangchun; Jiang, Bei; Zhou, Zunchun; Zhan, Aibin

2016-01-15

As invasive species have successfully colonized a wide range of dramatically different local environments, they offer a good opportunity to study interactions between species and rapidly changing environments. Gene expression represents one of the primary and crucial mechanisms for rapid adaptation to local environments. Here, we aim to select reference genes for quantitative gene expression analysis based on quantitative Real-Time PCR (qRT-PCR) for a model invasive ascidian, Ciona savignyi. We analyzed the stability of ten candidate reference genes in three tissues (siphon, pharynx and intestine) under two key environmental stresses (temperature and salinity) in the marine realm based on three programs (geNorm, NormFinder and delta Ct method). Our results demonstrated only minor difference for stability rankings among the three methods. The use of different single reference gene might influence the data interpretation, while multiple reference genes could minimize possible errors. Therefore, reference gene combinations were recommended for different tissues - the optimal reference gene combination for siphon was RPS15 and RPL17 under temperature stress, and RPL17, UBQ and TubA under salinity treatment; for pharynx, TubB, TubA and RPL17 were the most stable genes under temperature stress, while TubB, TubA and UBQ were the best under salinity stress; for intestine, UBQ, RPS15 and RPL17 were the most reliable reference genes under both treatments. Our results suggest that the necessity of selection and test of reference genes for different tissues under varying environmental stresses. The results obtained here are expected to reveal mechanisms of gene expression-mediated invasion success using C. savignyi as a model species. Copyright © 2015 Elsevier B.V. All rights reserved.

Bi-polarized translation of ascidian maternal mRNA determinant pem-1 associated with regulators of the translation machinery on cortical Endoplasmic Reticulum (cER).

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Paix, Alexandre; Le Nguyen, Phuong Ngan; Sardet, Christian

2011-09-01

Polarized cortical mRNA determinants such as maternal macho-1 and pem-1 in ascidians, like budding yeast mating factor ASH1 reside on the cER-mRNA domain a subdomain of cortical Endoplasmic Reticulum(ER) and are translated in its vicinity. Using high resolution imaging and isolated cortical fragments prepared from eggs and embryos we now find that macho-1 and pem-1 RNAs co-localize with phospho-protein regulators of translation initiation (MnK/4EBP/S6K). Translation of cortical pem-1 RNA follows its bi-polarized relocalization. About 10 min after fertilization or artificial activation with a calcium ionophore, PEM1 protein is detected in the vegetal cortex in the vicinity of pem-1 RNA. About 40 min after fertilization-when pem-1 RNA and P-MnK move to the posterior pole-PEM1 protein remains in place forming a network of cortical patches anchored at the level of the zygote plasma membrane before disappearing. Cortical PEM1 protein is detected again at the 4 cell stage in the posterior centrosome attracting body (CAB) region where the cER-mRNA domain harboring pem-1/P-MnK/P-4EBP/P-S6K is concentrated. Bi-polarized PEM1 protein signals are not detected when pem-1 morpholinos are injected into eggs or zygotes or when MnK is inhibited. We propose that localized translation of the pem-1 RNA determinant is triggered by the fertilization/calcium wave and that the process is controlled by phospho-protein regulators of translation initiation co-localized with the RNA determinant on a sub-domain of the cortical Endoplasmic Reticulum. Copyright © 2011 Elsevier Inc. All rights reserved.

Isolation of C11 Cyclopentenones from Two Didemnid Species, Lissoclinum sp. and Diplosoma sp.

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Katsuhiro Ueda

2009-12-01

Full Text Available A series of new C11 cyclopentenones 1-7 was isolated, together with four known metabolites 9/10, 12 and 13, from the extract of the didemnid ascidian Lissoclinum sp. The other didemnid ascidian Diplosoma sp. contained didemnenones 1, 2 and 5, and five known metabolites 8-12. The structures of 1-7 were elucidated by spectroscopic analyses. Cytotoxicity of the isolated compounds was evaluated against three human cancer cell lines (HCT116, A431 and A549.

Recent N-Atom Containing Compounds from Indo-Pacific Invertebrates

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Ashgan Bishara

2010-11-01

Full Text Available A large variety of unique N-atom containing compounds (alkaloids without terrestrial counterparts, have been isolated from marine invertebrates, mainly sponges and ascidians. Many of these compounds display interesting biological activities. In this report we present studies on nitrogenous compounds, isolated by our group during the last few years, from Indo-Pacific sponges, one ascidian and one gorgonian. The major part of the review deals with metabolites from the Madagascar sponge Fascaplysinopsis sp., namely, four groups of secondary metabolites, the salarins, tulearins, taumycins and tausalarins.

The mitochondrial genome of Phallusia mammillata and Phallusia fumigata (Tunicata, Ascidiacea: high genome plasticity at intra-genus level

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Pesole Graziano

2007-08-01

Full Text Available Abstract Background Within Chordata, the subphyla Vertebrata and Cephalochordata (lancelets are characterized by a remarkable stability of the mitochondrial (mt genome, with constancy of gene content and almost invariant gene order, whereas the limited mitochondrial data on the subphylum Tunicata suggest frequent and extensive gene rearrangements, observed also within ascidians of the same genus. Results To confirm this evolutionary trend and to better understand the evolutionary dynamics of the mitochondrial genome in Tunicata Ascidiacea, we have sequenced and characterized the complete mt genome of two congeneric ascidian species, Phallusia mammillata and Phallusia fumigata (Phlebobranchiata, Ascidiidae. The two mtDNAs are surprisingly rearranged, both with respect to one another and relative to those of other tunicates and chordates, with gene rearrangements affecting both protein-coding and tRNA genes. The new data highlight the extraordinary variability of ascidian mt genome in base composition, tRNA secondary structure, tRNA gene content, and non-coding regions (number, size, sequence and location. Indeed, both Phallusia genomes lack the trnD gene, show loss/acquisition of DHU-arm in two tRNAs, and have a G+C content two-fold higher than other ascidians. Moreover, the mt genome of P. fumigata presents two identical copies of trnI, an extra tRNA gene with uncertain amino acid specificity, and four almost identical sequence regions. In addition, a truncated cytochrome b, lacking a C-terminal tail that commonly protrudes into the mt matrix, has been identified as a new mt feature probably shared by all tunicates. Conclusion The frequent occurrence of major gene order rearrangements in ascidians both at high taxonomic level and within the same genus makes this taxon an excellent model to study the mechanisms of gene rearrangement, and renders the mt genome an invaluable phylogenetic marker to investigate molecular biodiversity and speciation

Isolation and biological activities of secondary metabolites from the sponges monanchora aff. arbuscula, aplysina sp. petromica ciocalyptoides and topsentia ophiraphidies, from the ascidian didemnum ligulum and from the octocoral carijoa riisei; Isolamento e atividades biologicas de produtos naturais das esponjas monanchora arbuscula, aplysina sp., petromica ciocalyptoides e topsentia ophiraphidites, da ascidia didemnum ligulum e do octocoral carijoa riisei

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Kossuga, Miriam H.; Lira, Simone P. de; Nascimento, Andrea M.; Gambardella, Maria Teresa P.; Berlinck, Roberto G.S. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: rgsberlinck@iqsc.usp.br; Torres, Yohandra R. [Universidade Estadual do Centro-Oeste, Guarapuava, PR (Brazil). Dept. de Quimica; Nascimento, Gislene G.F. [Universidade Metodista de Piracicaba (UNIMEP), SP (Brazil). Faculdade de Ciencias da Saude; Pimenta, Eli F.; Silva, Marcio; Thiemann, Otavio H.; Oliva, Glaucius [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica; Tempone, Andre G.; Melhem, Marcia S.C. [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil). Div. de Biologia Medica; Souza, Ana O. de; Galetti, Fabio C.S.; Silva, Celio L. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Dept. de Bioquimica e Imunologia; Cavalcanti, Bruno; Pessoa, Claudia O.; Moraes, Manoel O. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Faculdade de Medicina. Dept. de Fisiologia e Farmacologia; Hajdu, Eduardo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Museu Nacional; Peixinho, Solange [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Dept. de Biologia; Rocha, Rosana M. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Setor de Ciencias Biologicas. Dept. de Zoologia

2007-09-15

The investigation of extracts from six species of marine invertebrates yielded one new and several known natural products. Isoptilocaulin from the sponge Monanchora aff. arbuscula displayed antimicrobial activity at 1.3 mg/mL against an oxacillin-resistant strain of Staphylococcus aureus. Five inactive known dibromotyrosine derivatives, 2 6, were isolated from a new species of marine sponge, Aplysina sp. The sponges Petromica ciocalyptoides and Topsentia ophiraphidites yielded the known halistanol sulfate A (7) as an inhibitor of the antileishmanial target adenosine phosphoribosyl transferase. The ascidian Didemnum ligulum yielded asterubin (10) and the new N,N-dimethyl-O-methylethanolamine (11). The octocoral Carijoa riisei yielded the known 18-acetoxypregna-1,4,20-trien-3-one (12), which displayed cytotoxic activity against the cancer cell lines SF295, MDA-MB435, HCT8 and HL60. (author)

Produtos naturais da ascídia Botrylloides giganteum, das esponjas Verongula gigantea, Ircinia felix, Cliona delitrix e do nudibrânquio Tambja eliora, da costa do Brasil Natural products from the ascidian Botrylloides giganteum, from the sponges Verongula gigantea, Ircinia felix, Cliona delitrix and from the nudibranch Tambja eliora, from the Brazilian coastline

Directory of Open Access Journals (Sweden)

Ana Claudia Granato

2005-03-01

Full Text Available Two new marine metabolites, 3Z, 6Z, 9Z-dodecatrien-1-ol (1 from the ascidian Botrylloides giganteum and 4H-pyran-2ol acetate from the sponge Ircinia felix (4 are herein reported. The known bromotyrosine compounds, 2-(3,5-dibromo-4-methoxyphenyl-N,N,N-dimethylethanammonium (2 and 2,6-dibromo-4-(2-(trimethylammoniumethylphenol (3, have been isolated from the sponge Verongula gigantea. Serotonin (5 is reported for the first time from the sponge Cliona delitrix, and tambjamines A (15 and D (16 isolated as their respective salts from the nudibranch Tambja eliora. Only tambjamine D presented cytotoxicity against CEM (IC50 12.2 µg/mL and HL60 (IC50 13.2 µg/mL human leukemya cells, MCF-7 breast cancer cells (IC50 13.2 µg/mL, colon HCT-8 cancer cells (IC50 10.1 µg/mL and murine melanoma B16 cancer cells (IC50 6.7 µg/mL.

Natural products from the ascidian Botrylloides giganteum, from the sponges Verongula gigantea, Ircinia felix, Cliona delitrix and from the nudibranch Tambja eliora, from the Brazilian coastline; Produtos naturais da ascidia Botrylloides giganteum, das esponjas Verongula gigantea, Ircinia felix, Cliona delitrix e do nudibranquio Tambja eliora, da costa do Brasil

Energy Technology Data Exchange (ETDEWEB)

Granato, Ana Claudia; Oliveira, Jaine H.H.L. de; Seleghim, Mirna H.R.; Berlinck, Roberto G.S. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: rgsberlinck@iqsc.usp.br; Macedo, Mario L.; Ferreira, Antonio G. [Sao Carlos Univ., SP (Brazil). Dept. de Quimica; Rocha, Rosana M. da [Parana Univ., Curitiba, PR (Brazil). Setor de Ciencias Biologicas. Dept. de Zoologia; Hajdu, Eduardo [Universidade Federal, Rio de Janeiro, RJ (Brazil). Museu Nacional; Peixinho, Solange [Bahia Univ., Salvador, BA (Brazil). Dept. de Biologia; Pessoa, Claudia O.; Moraes, Manoel O.; Cavalcanti, Bruno C. [Ceara Univ., Fortaleza, CE (Brazil). Dept. de Fisiologia e Farmacologia

2005-04-01

Two new marine metabolites, 3Z, 6Z, 9Z-dodecatrien-1-ol (1) from the ascidian Botrylloides giganteum and 4H-pyran-2ol acetate from the sponge Ircinia felix (4) are herein reported. The known bromotyrosine compounds, 2-(3,5-dibromo-4-methoxyphenyl)-N,N,Ndimethylethanammonium (2) and 2,6-dibromo-4-(2-(trimethylammonium)ethyl)phenol (3), have been isolated from the sponge Verongula gigantea. Serotonin (5) is reported for the first time from the sponge Cliona delitrix, and tambjamines A (15) and D (16) isolated as their respective salts from the nudibranch Tambja eliora. Only tambjamine D presented cytotoxicity against CEM (IC{sub 5})0 12.2 {mu}g/mL) and HL60 (IC{sub 50} 13.2 {mu}g/mL) human leukemia cells, MCF-7 breast cancer cells (IC{sub 50} 13.2 {mu}g/mL), colon HCT-8 cancer cells (IC{sub 50} 10.1 {mu}g/mL) and murine melanoma B16 cancer cells (IC{sub 50} 6.7 {mu}g/mL). (author)

Ascidian Sperm Lysin System

OpenAIRE

Hitoshi, Sawada; Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University

2002-01-01

Fertilization is a precisely controlled process involving many gamete molecules in sperm binding to and penetration through the extracellular matrix of the egg. After sperm bind to the extracellular matrix (vitelline coat), they undergo the acrosome reaction which exposes and partially releases a lytic agent called "lysin" to digest the vitelline coat for the sperm penetration. The vitelline coat sperm lysin is generally a protease in deuterostomes. The molecular mechanism of the actual degra...

Details of the evolutionary history from invertebrates to vertebrates, as deduced from the sequences of 18S rDNA.

Science.gov (United States)

Wada, H; Satoh, N

1994-01-01

Almost the entire sequences of 18S rDNA were determined for two chaetognaths, five echinoderms, a hemichordate, and two urochordates (a larvacean and a salp). Phylogenetic comparisons of the sequences, together with those of other deuterostomes (an ascidian, a cephalochordate, and vertebrates) and protostomes (an arthropod and a mollusc), suggest the monophyly of the deuterostomes, with the exception of the chaetognaths. Chaetognaths may not be a group of deuterostomes. The deuterostome group closest to vertebrates was the group of cephalochordates. Ascidians, larvaceans, and salps seem to form a discrete group (urochordates), in which the early divergence of larvaceans is evident. These results support the hypothesis that chordates evolved from free-living ancestors. PMID:8127885

Larvae of fouling organisms and macrofouling at New Mangalore Port, west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Khandeparker, D.C.; Anil, A.C.; Venkat, K.

throughout the year, their representation in the macrofouling community was not prominent and yielded a poor correlation with recruitment. Bryozoan and ascidian larvae were sparsely encountered but indicated as significant correlation with their recruitment...

Structural models of vanadate-dependent haloperoxidases and their ...

Indian Academy of Sciences (India)

respectively. These complexes are not very stable in solution and slowly convert to the corresponding di- ... histidine moves to a basal position giving rise to a .... ORTEP plot (at 50% probability level) of ..... by certain ascidians (sea squirts).

NA phylogeny of Ryukyus Leucothoidae (Crustacea: Amphipoda)

NARCIS (Netherlands)

White, K.N.; Reimer, J.D.

2012-01-01

Commensal leucothoid amphipods collected from sponges, ascidians, and coral rubble from the Ryukyu Archipelago, Japan, were investigated using nuclear 18S ribosomal DNA sequences. Analysis of sequences from 21 species in three genera supported the current morphological species designations and the

Ecology: a niche for cyanobacteria containing chlorophyll d

DEFF Research Database (Denmark)

Kühl, Michael; Chen, Min; Ralph, Peter J

2005-01-01

we demonstrate photosynthetic activity in Acaryochloris-like phototrophs that live underneath minute coral-reef invertebrates (didemnid ascidians) in a shaded niche enriched in near-infrared light. This discovery clarifies how these cyanobacteria are able to thrive as free-living organisms...

Preliminary study on the occurrence of brominated organic compounds in Dutch marine organisms

NARCIS (Netherlands)

Kotterman, M.J.J.; Veen, van der I.; Hesselingen, van J.M.; Leonards, P.E.G.; Osinga, R.; Boer, de J.

2003-01-01

The extracts of three marine organisms; the ascidian Ciona intestinalis, the brown seaweed Sargassum muticum and the sponge Halichondria panicea, all elicited a number of brominated compounds, some of which were tentatively identified. Tribromophenol was observed in all species. This compound, also

A new species of Streblosoma Sars, 1872 (Polychaeta, Terebellidae, Thelepodinae) from Brazil, with comments on Streblosoma oligobranchiatum Nogueira & Amaral, 2001

NARCIS (Netherlands)

Matos Nogueira, de João Miguel; Garraffoni, André Rinaldo Senna; Montrezoro Alves, Tarsila

2004-01-01

A new species of Streblosoma is described and the diagnosis of S. oligobranchiatum is emended, based on material collected on intertidal rocky shores along the State of São Paulo, Brazil, associated with algae, sponges, ascidians and other sedentary polychaetes. Streblosoma porchatensis n. sp. is

African Journal of Biotechnology - Vol 13, No 27 (2014)

African Journals Online (AJOL)

High production of fructooligosaccharides by levansucrase from Bacillus subtilis natto CCT 7712 · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD ... Response surface method to optimize the low cost medium for protease production using anchovy meal from ascidian associated Bacillus sp. GA CAS10.

Response surface method to optimize the low cost medium for ...

African Journals Online (AJOL)

A protease producing Bacillus sp. GA CAS10 was isolated from ascidian Phallusia arabica, Tuticorin, Southeast coast of India. Response surface methodology was employed for the optimization of different nutritional and physical factors for the production of protease. Plackett-Burman method was applied to identify ...

Some notes on Notodelphys rufescens Thorell, 1860, new to the Dutch Fauna

NARCIS (Netherlands)

Stock, J.H.

1951-01-01

In September and October 1950, Mr. C. Swaneveld, of Zierikzee, and Mr. Jac. Viergever, of Serooskerke, collected some rich samples of Copepods, found alive in the branchial sac of certain species of Tunicates. The greater part of the Tunicates belonged to the Ascidian-species Ascidiella aspersa (O.

Particle-capture mechanisms in suspension-feeding invertebrates

DEFF Research Database (Denmark)

Riisgård, Hans Ulrik; Larsen, Poul Scheel

2010-01-01

A large number of suspension-feeding animals (e.g. bivalves, polychaetes, ascidians, bryozoans, crustaceans, sponges, echinoderms, cnidarians) have specialized in grazing on not only the 2 to 200 µm phytoplankton but frequently also the 0.5 to 2 µm free-living bacteria in the aquatic environment,...

Effects of simulated eutrophication and overfishing on algae and invertebrate settlement in a coral reef of Koh Phangan, Gulf of Thailand.

Science.gov (United States)

Stuhldreier, Ines; Bastian, Pepe; Schönig, Eike; Wild, Christian

2015-03-15

Coral reefs in the Gulf of Thailand are highly under-investigated regarding responses to anthropogenic stressors. Thus, this study simulated overfishing and eutrophication using herbivore exclosure cages and slow-release fertilizer to study the in-situ effects on benthic algae and invertebrate settlement in a coral reef of Koh Phangan, Thailand. Settlement of organisms and the development of organic matter on light-exposed and shaded tiles were quantified weekly/biweekly over a study period of 12 weeks. Simulated eutrophication did not significantly influence response parameters, while simulated overfishing positively affected dry mass, turf algae height and fleshy macroalgae occurrence on light-exposed tiles. On shaded tiles, settlement of crustose coralline algae decreased, while abundances of ascidians increased compared to controls. An interactive effect of both stressors was not observed. These results hint to herbivory as actual key controlling factor on the benthic community, and fleshy macroalgae together with ascidians as potential bioindicators for local overfishing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycosaminoglycans analogues from marine invertebrates: structure, biological effects and potential as new therapeutics.

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Mauro Sergio Pavao

2014-09-01

Full Text Available In this review, several glycosaminoglycan analogs obtained from different marine invertebrate are reported. The structure, biological activity and mechanism of action of these unique molecules are detailed reviewed and exemplified by experiments in vitro and in vivo. Among the glycans studied are low-sulfated heparin-like polymers from ascidians, containing significant anticoagulant activity and no bleeding effect; dermatan sulfates with significant neurite outgrowth promoting activity and anti-P-selectin from ascidians, and a unique fucosylated chondroitin sulfate from sea cucumbers, possessing anticoagulant activity after oral administration and high anti P- and L-selectin activities. The therapeutic value and safety of these invertebrate glycans have been extensively proved by several experimental animal models of diseases, including thrombosis, inflammation and metastasis. These invertebrate glycans can be obtained in high concentrations from marine organisms that have been used as a food source for decades, and usually obtained from marine farms in sufficient quantities to be used as starting material for new therapeutics.

Ascidians from Caribbean shallow water localities

NARCIS (Netherlands)

Goodbody, Ivan

1984-01-01

Between 1930 and 1973 PIETER WAGENAAR HUMMELINCK of the Zoölogisch Laboratorium of the State University of Utrecht made nine collecting trips to the Caribbean. While most collecting was undertaken in the territories of the Netherlands Antilles, visits were also made to several other West Indian

Immunohistochemical study of the nervous system of the tunicate Thalia democratica (Forsskal, 1775

Directory of Open Access Journals (Sweden)

R. Pennati

2012-04-01

Full Text Available Thalia democratica is a cosmopolitan tunicate belonging to the Thaliacea class. To further investigate the anatomy of this species, immunohistochemical labelling was performed using anti-tubulin and anti-serotonin antibodies on specimens collected in the Mediterranean Sea. The anti-tubulin antibody stained the cilia of the endostyle, the pericoronal bands and of the gill bar, enabling a detailed description of these structures. Moreover, immunolabelling of the nervous system showed the presence of eight pairs of nerve fibres emerging from the neural ganglion. Serotonergic cells were observed in the distal tract of the intestine, along the pericoronal bands, and in the placenta of gravid blastozooids, as well as in the neural ganglion. The presence of serotonin in the central nervous system has also been reported in the larvae of ascidians and may be linked to the planktonic life of these animals, a condition shared by adult thaliaceans and ascidian larvae. This work improves our knowledge of the anatomy of T. democratica and demonstrates the presence of a complex serotonergic system.

from Pyura stolollifera (Echinodermata, Ascidiacea)

African Journals Online (AJOL)

1994-05-05

May 5, 1994 ... Doropygus pyurus verskil van die meeste van die spesies in die genus t.o.v. die struktuur van die antennule an monddele, maar veral van D. pulex a.g.v. die unieke samestelling van die swempote. Species of the genus DoropyguJ Thorell, 1859 are cosmopo- litan, pharyngeal associates of ascidians, which ...

Focusing on Ciona intestinalis (Tunicata) innate immune system. Evolutionary implications

OpenAIRE

N Parrinello

2009-01-01

Phylogenetic analyses based on molecular data provide compelling evidence that ascidians are of critical importance for studying chordate immune system evolution. The Ciona intestinalis draft genome sequence allows searches for phylogenetic relationships, gene cloning and expression of immunorelevant molecules. Acidians lack of the pivotal components of the vertebrate recombinatory adaptive immunity, i.e., MHC, TCRs and dimeric immunoglobulins. However, bioinformatic sequence analyses recogni...

The Ciona intestinalis immune-related galectin genes (CiLgals-a and CiLgals-b) are expressed by the gastric epithelium.

Science.gov (United States)

Parrinello, Daniela; Sanfratello, Maria Antonietta; Vizzini, Aiti; Testasecca, Lelia; Parrinello, Nicolò; Cammarata, Matteo

2017-03-01

The transcription of two Ciona intestinalis galectin genes (CiLgals-a and CiLgals-b) is uparegulated by LPS in the pharynxis (hemocytes, vessel epithelium, endostilar zones) which is retained the main organ of the immunity. In this ascidian, for the first time we show, by immunohistochemistry and in situ hybridization methods, that these two immune-related genes are expressed in the gastric epithelium of naïve ascidians, whereas the galectins appear to be only contained in the intestine columnar epithelium. In addition, according to previous results on the pharynx, the genes are also expressed and galectins produced by hemocytes scattered in the connective tissue surrounding the gut. The genes expression and galectin localization in several tissues, including the previous findings on the transcription upregulation, the constitutive expression of these genes by endostylar zones and by the gastric epithelium suggest a potential multifunctional role of these galectins. In this respect, it is of interest to define where the CiLgals are normally found as related to the tissue functions. Such an approach should be a starting point for further investigations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cyanobacterial diversity and a new acaryochloris-like symbiont from Bahamian sea-squirts.

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Susanna López-Legentil

Full Text Available Symbiotic interactions between ascidians (sea-squirts and microbes are poorly understood. Here we characterized the cyanobacteria in the tissues of 8 distinct didemnid taxa from shallow-water marine habitats in the Bahamas Islands by sequencing a fragment of the cyanobacterial 16S rRNA gene and the entire 16S-23S rRNA internal transcribed spacer region (ITS and by examining symbiont morphology with transmission electron (TEM and confocal microscopy (CM. As described previously for other species, Trididemnum spp. mostly contained symbionts associated with the Prochloron-Synechocystis group. However, sequence analysis of the symbionts in Lissoclinum revealed two unique clades. The first contained a novel cyanobacterial clade, while the second clade was closely associated with Acaryochloris marina. CM revealed the presence of chlorophyll d (chl d and phycobiliproteins (PBPs within these symbiont cells, as is characteristic of Acaryochloris species. The presence of symbionts was also observed by TEM inside the tunic of both the adult and larvae of L. fragile, indicating vertical transmission to progeny. Based on molecular phylogenetic and microscopic analyses, Candidatus Acaryochloris bahamiensis nov. sp. is proposed for this symbiotic cyanobacterium. Our results support the hypothesis that photosymbiont communities in ascidians are structured by host phylogeny, but in some cases, also by sampling location.

Natural variation of model mutant phenotypes in Ciona intestinalis.

Directory of Open Access Journals (Sweden)

Paolo Sordino

Full Text Available BACKGROUND: The study of ascidians (Chordata, Tunicata has made a considerable contribution to our understanding of the origin and evolution of basal chordates. To provide further information to support forward genetics in Ciona intestinalis, we used a combination of natural variation and neutral population genetics as an approach for the systematic identification of new mutations. In addition to the significance of developmental variation for phenotype-driven studies, this approach can encompass important implications in evolutionary and population biology. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report a preliminary survey for naturally occurring mutations in three geographically interconnected populations of C. intestinalis. The influence of historical, geographical and environmental factors on the distribution of abnormal phenotypes was assessed by means of 12 microsatellites. We identified 37 possible mutant loci with stereotyped defects in embryonic development that segregate in a way typical of recessive alleles. Local populations were found to differ in genetic organization and frequency distribution of phenotypic classes. CONCLUSIONS/SIGNIFICANCE: Natural genetic polymorphism of C. intestinalis constitutes a valuable source of phenotypes for studying embryonic development in ascidians. Correlating genetic structure and the occurrence of abnormal phenotypes is a crucial focus for understanding the selective forces that shape natural finite populations, and may provide insights of great importance into the evolutionary mechanisms that generate animal diversity.

Natural Variation of Model Mutant Phenotypes in Ciona intestinalis

Science.gov (United States)

Brown, Euan R.; Leccia, Nicola I.; Squarzoni, Paola; Tarallo, Raffaella; Alfano, Christian; Caputi, Luigi; D'Ambrosio, Palmira; Daniele, Paola; D'Aniello, Enrico; D'Aniello, Salvatore; Maiella, Sylvie; Miraglia, Valentina; Russo, Monia Teresa; Sorrenti, Gerarda; Branno, Margherita; Cariello, Lucio; Cirino, Paola; Locascio, Annamaria; Spagnuolo, Antonietta; Zanetti, Laura; Ristoratore, Filomena

2008-01-01

Background The study of ascidians (Chordata, Tunicata) has made a considerable contribution to our understanding of the origin and evolution of basal chordates. To provide further information to support forward genetics in Ciona intestinalis, we used a combination of natural variation and neutral population genetics as an approach for the systematic identification of new mutations. In addition to the significance of developmental variation for phenotype-driven studies, this approach can encompass important implications in evolutionary and population biology. Methodology/Principal Findings Here, we report a preliminary survey for naturally occurring mutations in three geographically interconnected populations of C. intestinalis. The influence of historical, geographical and environmental factors on the distribution of abnormal phenotypes was assessed by means of 12 microsatellites. We identified 37 possible mutant loci with stereotyped defects in embryonic development that segregate in a way typical of recessive alleles. Local populations were found to differ in genetic organization and frequency distribution of phenotypic classes. Conclusions/Significance Natural genetic polymorphism of C. intestinalis constitutes a valuable source of phenotypes for studying embryonic development in ascidians. Correlating genetic structure and the occurrence of abnormal phenotypes is a crucial focus for understanding the selective forces that shape natural finite populations, and may provide insights of great importance into the evolutionary mechanisms that generate animal diversity. PMID:18523552

Phallusiasterol C, A New Disulfated Steroid from the Mediterranean Tunicate Phallusia fumigata

Directory of Open Access Journals (Sweden)

Concetta Imperatore

2016-06-01

Full Text Available A new sulfated sterol, phallusiasterol C (1, has been isolated from the Mediterranean ascidian Phallusia fumigata and its structure has been determined on the basis of extensive spectroscopic (mainly 2D NMR analysis. The possible role in regulating the pregnane X receptor (PXR activity of phallusiasterol C has been investigated; although the new sterol resulted inactive, this study adds more items to the knowledge of the structure-PXR regulating activity relationships in the case of sulfated steroids.

Viscosity and not biological mechanisms often controls the effects of temperature on ciliary activity and swimming velocity of small aquatic organisms

DEFF Research Database (Denmark)

Larsen, Poul Scheel; Riisgård, H. U.

2009-01-01

organisms using cilia or small appendages for propulsion. Here we summarize results from the literature and from own studies on bio-mechanical activities in response to changing temperature or manipulated viscosity at constant temperature, both having the same change in kinematic viscosity. The survey......A number of studies have shown that temperature-dependent viscosity of the ambient water controls or strongly affects bio-mechanical activity such as beat frequency of water-pumping cilia in mussels and ascidians, swimming velocity of sperm cells, ciliates and small (micro- and meso-scale) aquatic...

Redeployment of germ layers related TFs shows regionalized expression during two non-embryonic developments.

Science.gov (United States)

Ricci, Lorenzo; Cabrera, Fabien; Lotito, Sonia; Tiozzo, Stefano

2016-08-01

In all non-vertebrate metazoan phyla, species that evolved non-embryonic developmental pathways as means of propagation or regeneration can be found. In this context, new bodies arise through asexual reproduction processes (such as budding) or whole body regeneration, that lack the familiar temporal and spatial cues classically associated with embryogenesis, like maternal determinants, or gastrulation. The molecular mechanisms underlying those non-embryonic developments (i.e., regeneration and asexual reproduction), and their relationship to those deployed during embryogenesis are poorly understood. We have addressed this question in the colonial ascidian Botryllus schlosseri, which undergoes an asexual reproductive process via palleal budding (PB), as well as a whole body regeneration by vascular budding (VB). We identified early regenerative structures during VB and then followed the fate of differentiating tissues during both non-embryonic developments (PB and VB) by monitoring the expression of genes known to play key functions in germ layer specification with well conserved expression patterns in solitary ascidian embryogenesis. The expression patterns of FoxA1, GATAa, GATAb, Otx, Bra, Gsc and Tbx2/3 were analysed during both PB and VB. We found that the majority of these transcription factors were expressed during both non-embryonic developmental processes, revealing a regionalization of the palleal and vascular buds. Knockdown of GATAa by siRNA in palleal buds confirmed that preventing the correct development of one of these regions blocks further tissue specification. Our results indicate that during both normal and injury-induced budding, a similar alternative developmental program operates via early commitment of epithelial regions. Copyright © 2016. Published by Elsevier Inc.

Fungicidal compounds from a marine Ascidian-associated fungus Trichoderma harzianum

Digital Repository Service at National Institute of Oceanography (India)

PrabhaDevi; Ciavatta, M.L.; Wahidullah, S.; Vuppala, S.; DeSouza, L.

. Of the five isolated secondary metabolites, compounds 2 and 5 are being reported here for the first time from T. harzianum. Compounds 1 and 4 inhibited the growth of Sclerotium rolfsii causing sclerotium wilt or rot disease in tropical plants. Compound 2 and 5...

Tube formation by complex cellular processes in Ciona intestinalis notochord.

Science.gov (United States)

Dong, Bo; Horie, Takeo; Denker, Elsa; Kusakabe, Takehiro; Tsuda, Motoyuki; Smith, William C; Jiang, Di

2009-06-15

In the course of embryogenesis multicellular structures and organs are assembled from constituent cells. One structural component common to many organs is the tube, which consists most simply of a luminal space surrounded by a single layer of epithelial cells. The notochord of ascidian Ciona forms a tube consisting of only 40 cells, and serves as a hydrostatic "skeleton" essential for swimming. While the early processes of convergent extension in ascidian notochord development have been extensively studied, the later phases of development, which include lumen formation, have not been well characterized. Here we used molecular markers and confocal imaging to describe tubulogenesis in the developing Ciona notochord. We found that during tubulogenesis each notochord cell established de novo apical domains, and underwent a mesenchymal-epithelial transition to become an unusual epithelial cell with two opposing apical domains. Concomitantly, extracellular luminal matrix was produced and deposited between notochord cells. Subsequently, each notochord cell simultaneously executed two types of crawling movements bi-directionally along the anterior/posterior axis on the inner surface of notochordal sheath. Lamellipodia-like protrusions resulted in cell lengthening along the anterior/posterior axis, while the retraction of trailing edges of the same cell led to the merging of the two apical domains. As a result, the notochord cells acquired endothelial-like shape and formed the wall of the central lumen. Inhibition of actin polymerization prevented the cell movement and tube formation. Ciona notochord tube formation utilized an assortment of common and fundamental cellular processes including cell shape change, apical membrane biogenesis, cell/cell adhesion remodeling, dynamic cell crawling, and lumen matrix secretion.

Biomixing generated by benthic filterfeeders: A diffusion model for near-bottom phytoplankton depletion

DEFF Research Database (Denmark)

Scheel Larsen, Poul; Riisgård, H.U.

1997-01-01

-feeders, the polychaete Nereis diversicolor and the ascidian Ciona intestinalis, respectively. The model is based on sinks located at inhalant openings and Fick's law with an effective diffusivity that decreases with distance above the bottom due to the biomixing generated by exhalant and inhalant feeding currents. For N....... intestinalis, having inhalant and exhalant openings situated about 0.05-0.1 m above the bottom and a higher and inclined exhalant jet velocity of about 0.1-0.2 m s-1, the concentration distributions show a nearly uniform depletion over a layer reaching a thickness of 0.2-0.3 m above the bottom due to high...

Recent Advances in Drug Discovery from South African Marine Invertebrates

Directory of Open Access Journals (Sweden)

Michael T. Davies-Coleman

2015-10-01

Full Text Available Recent developments in marine drug discovery from three South African marine invertebrates, the tube worm Cephalodiscus gilchristi, the ascidian Lissoclinum sp. and the sponge Topsentia pachastrelloides, are presented. Recent reports of the bioactivity and synthesis of the anti-cancer secondary metabolites cephalostatin and mandelalides (from C. gilchristi and Lissoclinum sp., respectively and various analogues are presented. The threat of drug-resistant pathogens, e.g., methicillin-resistant Staphylococcus aureus (MRSA, is assuming greater global significance, and medicinal chemistry strategies to exploit the potent MRSA PK inhibition, first revealed by two marine secondary metabolites, cis-3,4-dihydrohamacanthin B and bromodeoxytopsentin from T. pachastrelloides, are compared.

Evolutionary conservation of vertebrate notochord genes in the ascidian Ciona intestinalis.

Science.gov (United States)

Kugler, Jamie E; Passamaneck, Yale J; Feldman, Taya G; Beh, Jeni; Regnier, Todd W; Di Gregorio, Anna

2008-11-01

To reconstruct a minimum complement of notochord genes evolutionarily conserved across chordates, we scanned the Ciona intestinalis genome using the sequences of 182 genes reported to be expressed in the notochord of different vertebrates and identified 139 candidate notochord genes. For 66 of these Ciona genes expression data were already available, hence we analyzed the expression of the remaining 73 genes and found notochord expression for 20. The predicted products of the newly identified notochord genes range from the transcription factors Ci-XBPa and Ci-miER1 to extracellular matrix proteins. We examined the expression of the newly identified notochord genes in embryos ectopically expressing Ciona Brachyury (Ci-Bra) and in embryos expressing a repressor form of this transcription factor in the notochord, and we found that while a subset of the genes examined are clearly responsive to Ci-Bra, other genes are not affected by alterations in its levels. We provide a first description of notochord genes that are not evidently influenced by the ectopic expression of Ci-Bra and we propose alternative regulatory mechanisms that might control their transcription. Copyright 2008 Wiley-Liss, Inc.

Immunity in Protochordates: The Tunicate Perspective

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Nicola Franchi

2017-06-01

Full Text Available Tunicates are the closest relatives of vertebrates, and their peculiar phylogenetic position explains the increasing interest toward tunicate immunobiology. They are filter-feeding organisms, and this greatly influences their defense strategies. The majority of the studies on tunicate immunity were carried out in ascidians. The tunic acts as a first barrier against pathogens and parasites. In addition, the oral siphon and the pharynx represent two major, highly vascularized, immune organs, where circulating hemocytes can sense non-self material and trigger immune responses that, usually, lead to inflammation and phagocytosis. Inflammation involves the recruitment of circulating cytotoxic, phenoloxidase (PO-containing cells in the infected area, where they degranulate as a consequence of non-self recognition and release cytokines, complement factors, and the enzyme PO. The latter, acting on polyphenol substrata, produces cytotoxic quinones, which polymerize to melanin, and reactive oxygen species, which induce oxidative stress. Both the alternative and the lectin pathways of complement activation converge to activate C3: C3a and C3b are involved in the recruitment of hemocytes and in the opsonization of foreign materials, respectively. The interaction of circulating professional phagocytes with potentially pathogenic foreign material can be direct or mediated by opsonins, either complement dependent or complement independent. Together with cytotoxic cells, phagocytes are active in the encapsulation of large materials. Cells involved in immune responses, collectively called immunocytes, represent a large fraction of hemocytes, and the presence of a cross talk between cytotoxic cells and phagocytes, mediated by secreted humoral factors, was reported. Lectins play a pivotal role as pattern-recognition receptors and opsonizing agents. In addition, variable region-containing chitin-binding proteins, identified in the solitary ascidian Ciona

[Distribution of Ecteinascidia turbinata (Ascidiacea: Perophoridae) in mangroves of the Yucatán Peninsula, Mexico].

Science.gov (United States)

Carballo, J L

2000-01-01

The ascidian Ecteinascidia turbinata synthesizes some of the most promising substances against solid-type tumors, but the only available source are the natural populations of this tunicate, which is reared or collected in different parts of the world. A total of 33 locations were sampled in the Gulf of Mexico and the Yucatan Peninsula. The tunicate was not found in Veracruz, Tabasco and Campeche, but it was well established on mangrove roots in the Yucatan Peninsula where we estimated densities more or less equal to one colony and an average production of 115 g of biomass per lineal meter of mangrove coastline in one location (Río Lagartos). Sustainable management appears to be possible.

Dicty_cDB: Contig-U02054-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 0.080 1 ( DT656898 ) pgr1n.UA001.227 Normalized chicken reproductive t... 50 0.080 1 ( AJ454996 ) Gallus gallus EST, clone library...90810 XtSt10-30 Xenopus (Silurana) t... 36 0.17 2 ( DV037739 ) BRS3230 storage root cDNA library Ipomoea bat..... 44 4.9 1 ( BM959958 ) cihA1L9S Ascidian hemocytes cDNA library Ciona in... 44 4.9 1 ( BM230365 ) K0294C12-3 NIA Mouse Unferti...... 36 0.010 3 ( EY189411 ) LLAE1039S Spider Loxosceles laeta cDNA library Lo... ... riken1, clone 4e... 50 0.080 1 ( AJ453299 ) Gallus gallus EST, clone library riken1,

Marine bioactive compounds: stereospecific anti-inflammatory activity of natural and synthetic cordiachromene A.

Science.gov (United States)

Benslimane, A F; Pouchus, Y F; Verbist, J F; Petit, J Y; Khettab, E N; Welin, L; Brion, J D

1992-01-01

A new synthesis is proposed for cordiachromene A (CCA), a bioactive component of the ascidian Aplidium antillense Gravier, using a method producing a racemic mixture. The anti-inflammatory activities of a natural extract and a chemically synthetic form of CCA were assessed in vivo by carrageenan-induced rat-paw edema. The activity of synthetic CCA was confirmed by a test on kaolin-induced granuloma in the rat. Strong activities were measured for both CCA, but comparison of results of the first test suggests that only the natural optically active isomer has an anti-inflammatory effect. CCA is similar to indomethacin in its effect on carrageenan-induced rat-paw edema and ten times as active as phenylbutazone.

Genetic isolation among morphotypes in the photosymbiotic didemnid Didemnum molle (Ascidiacea, Tunicata) from the Ryukyus and Taiwan.

Science.gov (United States)

Hirose, Mamiko; Nozawa, Yoko; Hirose, Euichi

2010-12-01

Didemnum molle, a colonial ascidian that harbors the symbiotic cyanophyte Prochloron spp., is distributed throughout the coral reefs of the Indo-West Pacific Ocean. Several morphotypes of D. molle are characterized by the color and size of their colonies. Previous molecular phylogeny inferred from gene sequences for the cytochrome oxidase subunit I (COI) identified four morphotypes (i.e., gray, brown, white, and large) from several sites in the Ryukyu Islands, Japan. With the addition of 17 specimens, including another morphotype (small), from several collection sites (Taiwan and the Ryukyus), the present report demonstrates genetic separation among the five morphotypes based on COI sequences. A number of sexually mature specimens of the different morphotypes were collected at the same times and sites, indicating reproductive isolation among morphotypes.

Developmental toxicity of organotin compounds in animals

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Lijiao eWu

2014-09-01

Full Text Available Organotin compounds (OTs have been used as biocides in antifouling paints and agriculture. The IMO introduced a global ban on the use of OTs in antifouling systems in 2001 due to their high toxicity. However, OTs have still been detected in the environment and pose a threat to the ecosystem. Several research groups have summarized the analytical methods, environmental fate, biochemistry, reproductive toxicity and mechanisms of actions of OTs. Here, we reviewed the developmental toxicity of OTs in various organisms such as sea urchin, ascidian, mussel and fish. The differences in sensitivity to OT exposure exist not only in different species but also at different stages in the same species. Though some hypotheses have been proposed to explain the developmental toxicity of OTs, the solid evidences are greatly in need.

Cyanobactins from Cyanobacteria: Current Genetic and Chemical State of Knowledge.

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Martins, Joana; Vasconcelos, Vitor

2015-11-13

Cyanobacteria are considered to be one of the most promising sources of new, natural products. Apart from non-ribosomal peptides and polyketides, ribosomally synthesized and post-translationally modified peptides (RiPPs) are one of the leading groups of bioactive compounds produced by cyanobacteria. Among these, cyanobactins have sparked attention due to their interesting bioactivities and for their potential to be prospective candidates in the development of drugs. It is assumed that the primary source of cyanobactins is cyanobacteria, although these compounds have also been isolated from marine animals such as ascidians, sponges and mollusks. The aim of this review is to update the current knowledge of cyanobactins, recognized as being produced by cyanobacteria, and to emphasize their genetic clusters and chemical structures as well as their bioactivities, ecological roles and biotechnological potential.

Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis

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Chelsea E. Lopez

2017-07-01

Full Text Available Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island and 22°C (the upper end of the local temperature range. We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS. 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C group and high temperature (22°C group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.

Genome-wide single nucleotide polymorphisms (SNPs) for a model invasive ascidian Botryllus schlosseri.

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Gao, Yangchun; Li, Shiguo; Zhan, Aibin

2018-04-01

Invasive species cause huge damages to ecology, environment and economy globally. The comprehensive understanding of invasion mechanisms, particularly genetic bases of micro-evolutionary processes responsible for invasion success, is essential for reducing potential damages caused by invasive species. The golden star tunicate, Botryllus schlosseri, has become a model species in invasion biology, mainly owing to its high invasiveness nature and small well-sequenced genome. However, the genome-wide genetic markers have not been well developed in this highly invasive species, thus limiting the comprehensive understanding of genetic mechanisms of invasion success. Using restriction site-associated DNA (RAD) tag sequencing, here we developed a high-quality resource of 14,119 out of 158,821 SNPs for B. schlosseri. These SNPs were relatively evenly distributed at each chromosome. SNP annotations showed that the majority of SNPs (63.20%) were located at intergenic regions, and 21.51% and 14.58% were located at introns and exons, respectively. In addition, the potential use of the developed SNPs for population genomics studies was primarily assessed, such as the estimate of observed heterozygosity (H O ), expected heterozygosity (H E ), nucleotide diversity (π), Wright's inbreeding coefficient (F IS ) and effective population size (Ne). Our developed SNP resource would provide future studies the genome-wide genetic markers for genetic and genomic investigations, such as genetic bases of micro-evolutionary processes responsible for invasion success.

HSQC-TOCSY Fingerprinting for Prioritization of Polyketide- and Peptide-Producing Microbial Isolates.

Science.gov (United States)

Buedenbender, Larissa; Habener, Leesa J; Grkovic, Tanja; Kurtböke, D İpek; Duffy, Sandra; Avery, Vicky M; Carroll, Anthony R

2018-04-27

Microbial products are a promising source for drug leads as a result of their unique structural diversity. However, reisolation of already known natural products significantly hampers the discovery process, and it is therefore important to incorporate effective microbial isolate selection and dereplication protocols early in microbial natural product studies. We have developed a systematic approach for prioritization of microbial isolates for natural product discovery based on heteronuclear single-quantum correlation-total correlation spectroscopy (HSQC-TOCSY) nuclear magnetic resonance profiles in combination with antiplasmodial activity of extracts. The HSQC-TOCSY experiments allowed for unfractionated microbial extracts containing polyketide and peptidic natural products to be rapidly identified. Here, we highlight how this approach was used to prioritize extracts derived from a library of 119 ascidian-associated actinomycetes that possess a higher potential to produce bioactive polyketides and peptides.

Distribución y abundancia de la ascidia Ecteinascidia turbinata (Ascidiacea: Perophoridae en Cuba

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Aida Hernández-Zanuy

2007-03-01

Full Text Available Ecteinascidia turbinata está ampliamente distribuida en las áreas de mangle rojo (Rhizophora mangle de tipo sobrelavados donde ocupa la porción permanentemente sumergida. Ocasionalmente se encontró sobre el coral negro Antipathes caribeana a 22 y 38 m de profundidad. Sin embargo no fue frecuente en los manglares de borde ni de ribera. Se muestrearon 58 localidades estando presente la especie en un 75 % de las mismas. Sus poblaciones son abundantes pues en el 57 % de las zonas prospectadas más del 25 % de las raíces del manglar poseen al menos una colonia. Las mayores densidades se encontraron en la costa noroeste de Cuba (Pinar del Río con valores cercanos a una colonia por metro lineal de manglar, siendo Cayo Jutías la de mayor densidad (1.46 col/m. La mayor biomasa también se registró en la mencionada localidad con valores comprendidos entre 25 y 660 g/m lineal de manglar. El promedio general de la biomasa en los manglares estudiados fue de 73.63 g/m lineal de manglar.Distribution and abundance of the ascidian Ecteinascidia turbinata (Ascidiacea: Perophoridae in Cuba. Permanently submerged mangrove roots (Rhizophora mangle are the main habitat of the ascidian Ecteinascidia turbinata in Cuba. It was occasionally found on black coral (Antiphates caribeana between 22 and 38 meters deep. This species exhibits a wide distribution in all the mangrove keys surrounding the Island of Cuba but does not occur in riparian or fringing mangroves. Populations of this species are abundant in Cuba: in 75 % of the 58 localities sampled the species was present and in 57 % more than 50 % of the roots held at least one colony. The highest colony densities were found in the northern coast of Pinar del Río province with values near one colony per lineal meter of mangrove root. We found the highest density (1.46 col/m and greatest biomass at Jutías Key, with values between 25 and 660 g/m. The average of wet biomass in the studied mangroves was 73.63 g

Presence of the tunicate Asterocarpa humilis on ship hulls and aquaculture facilities in the coast of the Biobío Region, south central Chile

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Javier Pinochet

2017-08-01

Full Text Available Non-native ascidians are important members of the fouling community associated with artificial substrata and man-made structures. Being efficient fouling species, they are easily spread by human-mediated transports (e.g., with aquaculture trade and maritime transports. This is exemplified by the ascidian Asterocarpa humilis which displays a wide distribution in the Southern Hemisphere and has been recently reported in the Northern Hemisphere (NW Europe. In continental Chile, its first report dates back from 2000 for the locality of Antofagasta (23°S. Although there was no evidence about the vectors of introduction and spread, nor the source, some authors suggested maritime transport by ship hulls and aquaculture devices as putative introduction pathways and vectors. In the present study, we report for the first time the presence of A. humilis on the hull of an international ship in a commercial port in Concepción bay (36°S, south central Chile. We also found one individual associated to a seashell farm, 70 km far from Concepción bay. Further individuals were subsequently identified within Concepción bay: one juvenile settled upon international harbor pilings and a dozen individuals along aquaculture seashell longlines. For the first specimens sampled, species identification was ascertained using both morphological criteria and molecular barcoding, using the mitochondrial gene cytochrome c oxidase subunit I (COI and a nuclear gene (ribosomal RNA 18S. The nuclear 18S gene and the mitochondrial gene COI clearly assigned the specimens to A. humilis, confirming our morphological identification. Two haplotypes were obtained with COI corresponding to haplotypes previously obtained with European and Northern Chilean specimens. The present study thus reports for the first time the presence of A. humilis in the Araucanian ecoregion, documenting the apparent expansion of this non-native tunicate in Chile over 2,000 km, spanning over three ecoregions

Biophysical characterization of the fluorescent protein voltage probe VSFP2.3 based on the voltage-sensing domain of Ci-VSP

DEFF Research Database (Denmark)

Lundby, Alicia; Akemann, Walther; Knöpfel, Thomas

2010-01-01

A voltage sensitive phosphatase was discovered in the ascidian Ciona intestinalis. The phosphatase, Ci-VSP, contains a voltage-sensing domain homologous to those known from voltage-gated ion channels, but unlike ion channels, the voltage-sensing domain of Ci-VSP can reside in the cell membrane...... as a monomer. We fused the voltage-sensing domain of Ci-VSP to a pair of fluorescent reporter proteins to generate a genetically encodable voltage-sensing fluorescent probe, VSFP2.3. VSFP2.3 is a fluorescent voltage probe that reports changes in membrane potential as a FRET (fluorescence resonance energy....... Neutralization of an arginine in S4, previously suggested to be a sensing charge, and measuring associated sensing currents indicate that this charge is likely to reside at the membrane-aqueous interface rather than within the membrane electric field. The data presented give us insights into the voltage-sensing...

Natural antifouling compound production by microbes associated with marine macroorganisms — A review

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Sathianeson Satheesh

2016-05-01

Full Text Available In the marine environment, all hard surfaces including marine macroorganims are colonized by microorganisms mainly from the surrounding environment. The microorganisms associated with marine macroorganisms offer tremendous potential for exploitation of bioactive metabolites. Biofouling is a continuous problem in marine sectors which needs huge economy for control and cleaning processes. Biotechnological way for searching natural product antifouling compounds gained momentum in recent years because of the environmental pollution associated with the use of toxic chemicals to control biofouling. While, natural product based antifoulants from marine organisms particularly sponges and corals attained significance due to their activities in field assays, collection of larger amount of organisms from the sea is not a viable one. The microorganisms associated with sponges, corals, ascidians, seaweeds and seagrasses showed strong antimicrobial and also antifouling activities. This review highlights the advances in natural product antifoulants research from microbes associated with marine organisms.

Mussel dredging: Impact on epifauna in Limfjorden, Denmark

DEFF Research Database (Denmark)

Dolmer, Per

2002-01-01

Species composition and population density of epibenthos are described in two areas in Limfjorden, Denmark. Both areas covered both a mussel fishing ground and an area that has been permanently closed for mussel dredging since 1988. Furthermore, mussels were dredged in a part of the mussel fishing...... grounds in both areas four months before the investigations. The rest of the fishing grounds had not been exploited for at least four years. This study describes the short-term impact (4 mo) and long-term impact (>4 y) of mussel dredging using the permanently closed areas as controls. The data were...... analyzed by multivariate statistics. In both short-term study areas significant effects of dredging were observed. A number of taxa (sponges, echinoderms, anthozoans, molluscs, crustaceans, and ascidians) had a reduced density or were not observed in fished areas four months after the fishing was ended...

Ciona intestinalis notochord as a new model to investigate the cellular and molecular mechanisms of tubulogenesis.

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Denker, Elsa; Jiang, Di

2012-05-01

Biological tubes are a prevalent structural design across living organisms. They provide essential functions during the development and adult life of an organism. Increasing progress has been made recently in delineating the cellular and molecular mechanisms underlying tubulogenesis. This review aims to introduce ascidian notochord morphogenesis as an interesting model system to study the cell biology of tube formation, to a wider cell and developmental biology community. We present fundamental morphological and cellular events involved in notochord morphogenesis, compare and contrast them with other more established tubulogenesis model systems, and point out some unique features, including bipolarity of the notochord cells, and using cell shape changes and cell rearrangement to connect lumens. We highlight some initial findings in the molecular mechanisms of notochord morphogenesis. Based on these findings, we present intriguing problems and put forth hypotheses that can be addressed in future studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

The invasion risk of species associated with Japanese Tsunami Marine Debris in Pacific North America and Hawaii.

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Therriault, Thomas W; Nelson, Jocelyn C; Carlton, James T; Liggan, Lauran; Otani, Michio; Kawai, Hiroshi; Scriven, Danielle; Ruiz, Gregory M; Clarke Murray, Cathryn

2018-01-25

Marine debris from the Great Tsunami of 2011 represents a unique transport vector for Japanese species to reach Pacific North America and Hawaii. Here we characterize the invasion risk of invertebrate species associated with tsunami debris using a screening-level risk assessment tool - the Canadian Marine Invasive Screening Tool (CMIST). Higher-risk invertebrate invaders were identified for each of five different ecoregions. Some of these are well-known global invaders, such as the mussel Mytilus galloprovincialis and the ascidian Didemnum vexillum which already have invasion histories in some of the assessed ecoregions, while others like the sea star Asterias amurensis and the shore crab Hemigrapsus sanguineus have yet to invade large portions of the assessed ecoregions but also are recognized global invaders. In general, the probability of invasion was lower for the Gulf of Alaska and Hawaii, in part due to lower climate matches and the availability of other invasion vectors. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Simple model systems: a challenge for Alzheimer's disease

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Di Carlo Marta

2012-04-01

Full Text Available Abstract The success of biomedical researches has led to improvement in human health and increased life expectancy. An unexpected consequence has been an increase of age-related diseases and, in particular, neurodegenerative diseases. These disorders are generally late onset and exhibit complex pathologies including memory loss, cognitive defects, movement disorders and death. Here, it is described as the use of simple animal models such as worms, fishes, flies, Ascidians and sea urchins, have facilitated the understanding of several biochemical mechanisms underlying Alzheimer's disease (AD, one of the most diffuse neurodegenerative pathologies. The discovery of specific genes and proteins associated with AD, and the development of new technologies for the production of transgenic animals, has helped researchers to overcome the lack of natural models. Moreover, simple model systems of AD have been utilized to obtain key information for evaluating potential therapeutic interventions and for testing efficacy of putative neuroprotective compounds.

Bistratamides M and N, Oxazole-Thiazole Containing Cyclic Hexapeptides Isolated from Lissoclinum bistratum Interaction of Zinc (II with Bistratamide K

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Carlos Urda

2017-07-01

Full Text Available Two novel oxazole-thiazole containing cyclic hexapeptides, bistratamides M (1 and N (2 have been isolated from the marine ascidian Lissoclinum bistratum (L. bistratum collected in Raja Ampat (Papua Bar, Indonesia. The planar structure of 1 and 2 was assigned on the basis of extensive 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration of the amino acid residues in 1 and 2 was determined by the application of the Marfey’s and advanced Marfey’s methods after ozonolysis followed by acid-catalyzed hydrolysis. The interaction between zinc (II and the naturally known bistratamide K (3, a cyclic hexapeptide isolated from a different specimen of Lissoclinum bistratum, was monitored by 1H and 13C NMR. The results obtained are consistent with the proposal that these peptides are biosynthesized for binding to metal ions. Compounds 1 and 2 display moderate cytotoxicity against four human tumor cell lines with GI50 values in the micromolar range.

Marine natural product peptides with therapeutic potential: Chemistry, biosynthesis, and pharmacology.

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Gogineni, Vedanjali; Hamann, Mark T

2018-01-01

The oceans are a uniquely rich source of bioactive metabolites, of which sponges have been shown to be among the most prolific producers of diverse bioactive secondary metabolites with valuable therapeutic potential. Much attention has been focused on marine bioactive peptides due to their novel chemistry and diverse biological properties. As summarized in this review, marine peptides are known to exhibit various biological activities such as antiviral, anti-proliferative, antioxidant, anti-coagulant, anti-hypertensive, anti-cancer, antidiabetic, antiobesity, and calcium-binding activities. This review focuses on the chemistry and biology of peptides isolated from sponges, bacteria, cyanobacteria, fungi, ascidians, and other marine sources. The role of marine invertebrate microbiomes in natural products biosynthesis is discussed in this review along with the biosynthesis of modified peptides from different marine sources. The status of peptides in various phases of clinical trials is presented, as well as the development of modified peptides including optimization of PK and bioavailability. Copyright © 2017 Elsevier B.V. All rights reserved.

The identification of transcription factors expressed in the notochord of Ciona intestinalis adds new potential players to the brachyury gene regulatory network.

Science.gov (United States)

José-Edwards, Diana S; Kerner, Pierre; Kugler, Jamie E; Deng, Wei; Jiang, Di; Di Gregorio, Anna

2011-07-01

The notochord is the distinctive characteristic of chordates; however, the knowledge of the complement of transcription factors governing the development of this structure is still incomplete. Here we present the expression patterns of seven transcription factor genes detected in the notochord of the ascidian Ciona intestinalis at various stages of embryonic development. Four of these transcription factors, Fos-a, NFAT5, AFF and Klf15, have not been directly associated with the notochord in previous studies, while the others, including Spalt-like-a, Lmx-like, and STAT5/6-b, display evolutionarily conserved expression in this structure as well as in other domains. We examined the hierarchical relationships between these genes and the transcription factor Brachyury, which is necessary for notochord development in all chordates. We found that Ciona Brachyury regulates the expression of most, although not all, of these genes. These results shed light on the genetic regulatory program underlying notochord formation in Ciona and possibly other chordates. Copyright © 2011 Wiley-Liss, Inc.

Desiccation as a mitigation tool to manage biofouling risks: trials on temperate taxa to elucidate factors influencing mortality rates.

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Hopkins, Grant A; Prince, Madeleine; Cahill, Patrick L; Fletcher, Lauren M; Atalah, Javier

2016-01-01

The desiccation tolerance of biofouling taxa (adults and early life-stages) was determined under both controlled and 'realistic' field conditions. Adults of the ascidian Ciona spp. died within 24 h. Mortality in the adult blue mussel Mytilus galloprovincialis occurred within 11 d under controlled conditions, compared with 7 d when held outside. The Pacific oyster Crassostrea gigas was the most desiccation-tolerant taxon tested (up to 34 d under controlled conditions). Biofouling orientated to direct sunlight showed faster mortality rates for all the taxa tested. Mortality in Mytilus juveniles took up to 24 h, compared with 8 h for Ciona, with greater survival at the higher temperature (18.5°C) and humidity (~95% RH) treatment combination. This study demonstrated that desiccation can be an effective mitigation method for a broad range of fouling taxa, especially their early life-stages. Further work is necessary to assess risks from other high-risk species such as algae and cyst forming species.

Vessel generator noise as a settlement cue for marine biofouling species.

Science.gov (United States)

McDonald, J I; Wilkens, S L; Stanley, J A; Jeffs, A G

2014-01-01

Underwater noise is increasing globally, largely due to increased vessel numbers and international ocean trade. Vessels are also a major vector for translocation of non-indigenous marine species which can have serious implications for biosecurity. The possibility that underwater noise from fishing vessels may promote settlement of biofouling on hulls was investigated for the ascidian Ciona intestinalis. Spatial differences in biofouling appear to be correlated with spatial differences in the intensity and frequency of the noise emitted by the vessel's generator. This correlation was confirmed in laboratory experiments where C. intestinalis larvae showed significantly faster settlement and metamorphosis when exposed to the underwater noise produced by the vessel generator. Larval survival rates were also significantly higher in treatments exposed to vessel generator noise. Enhanced settlement attributable to vessel generator noise may indicate that vessels not only provide a suitable fouling substratum, but vessels running generators may be attracting larvae and enhancing their survival and growth.

Associated fauna and effects of epibiotic barnacles on the relative growth and reproductive indices of Stramonita haemastoma (Gastropoda: Muricidae

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Tahani El Ayari

2015-06-01

Full Text Available To better understand the impacts of biofouling on the biological processes of the basibiont, the effects of epibiotic barnacles on the relative growth and reproductive indices of Stramonita haemastoma (Linnaeus, 1767 were assessed. A total of 1035 specimens were collected monthly for one year from Bizerta Channel (northern Tunisia. Endobiotic species comprised the lithophagous bivalves Lithophaga aristata and Rocellaria dubia of different sizes, communicating with the outside through tiny perforations. Intra-shell tunnels and galleries also sheltered annelids and sipunculids. Epibiotic species comprised algae and highly diversified invertebrates represented by crustaceans, polychaetes, molluscs, echinoderms, ascidians, sponges, bryozoans and sipunculids, with barnacles being the most common group. Comparison of growth features between non-fouled and fouled S. haemastoma revealed higher growth in non-fouled specimens. Differences in reproductive condition indices were detected in few months, being mostly higher in non-fouled snails, but showed no asynchrony in the spawning period for either fouled or non-fouled gastropods hosts.

The CNS connectome of a tadpole larva of Ciona intestinalis (L.) highlights sidedness in the brain of a chordate sibling.

Science.gov (United States)

Ryan, Kerrianne; Lu, Zhiyuan; Meinertzhagen, Ian A

2016-12-06

Left-right asymmetries in brains are usually minor or cryptic. We report brain asymmetries in the tiny, dorsal tubular nervous system of the ascidian tadpole larva, Ciona intestinalis . Chordate in body plan and development, the larva provides an outstanding example of brain asymmetry. Although early neural development is well studied, detailed cellular organization of the swimming larva's CNS remains unreported. Using serial-section EM we document the synaptic connectome of the larva's 177 CNS neurons. These formed 6618 synapses including 1772 neuromuscular junctions, augmented by 1206 gap junctions. Neurons are unipolar with at most a single dendrite, and few synapses. Some synapses are unpolarised, others form reciprocal or serial motifs; 922 were polyadic. Axo-axonal synapses predominate. Most neurons have ciliary organelles, and many features lack structural specialization. Despite equal cell numbers on both sides, neuron identities and pathways differ left/right. Brain vesicle asymmetries include a right ocellus and left coronet cells.

A workflow to process 3D+time microscopy images of developing organisms and reconstruct their cell lineage

Science.gov (United States)

Faure, Emmanuel; Savy, Thierry; Rizzi, Barbara; Melani, Camilo; Stašová, Olga; Fabrèges, Dimitri; Špir, Róbert; Hammons, Mark; Čúnderlík, Róbert; Recher, Gaëlle; Lombardot, Benoît; Duloquin, Louise; Colin, Ingrid; Kollár, Jozef; Desnoulez, Sophie; Affaticati, Pierre; Maury, Benoît; Boyreau, Adeline; Nief, Jean-Yves; Calvat, Pascal; Vernier, Philippe; Frain, Monique; Lutfalla, Georges; Kergosien, Yannick; Suret, Pierre; Remešíková, Mariana; Doursat, René; Sarti, Alessandro; Mikula, Karol; Peyriéras, Nadine; Bourgine, Paul

2016-01-01

The quantitative and systematic analysis of embryonic cell dynamics from in vivo 3D+time image data sets is a major challenge at the forefront of developmental biology. Despite recent breakthroughs in the microscopy imaging of living systems, producing an accurate cell lineage tree for any developing organism remains a difficult task. We present here the BioEmergences workflow integrating all reconstruction steps from image acquisition and processing to the interactive visualization of reconstructed data. Original mathematical methods and algorithms underlie image filtering, nucleus centre detection, nucleus and membrane segmentation, and cell tracking. They are demonstrated on zebrafish, ascidian and sea urchin embryos with stained nuclei and membranes. Subsequent validation and annotations are carried out using Mov-IT, a custom-made graphical interface. Compared with eight other software tools, our workflow achieved the best lineage score. Delivered in standalone or web service mode, BioEmergences and Mov-IT offer a unique set of tools for in silico experimental embryology. PMID:26912388

Induction of divalent cation permeability by heterologous expression of a voltage sensor domain.

Science.gov (United States)

Arima, Hiroki; Tsutsui, Hidekazu; Sakamoto, Ayako; Yoshida, Manabu; Okamura, Yasushi

2018-01-06

The voltage sensor domain (VSD) is a protein domain that confers sensitivity to membrane potential in voltage-gated ion channels as well as the voltage-sensing phosphatase. Although VSDs have long been considered to function as regulatory units acting on adjacent effectors, recent studies have revealed the existence of direct ion permeation paths in some mutated VSDs and in the voltage-gated proton channel. In this study, we show that calcium currents are evoked upon membrane hyperpolarization in cells expressing a VSD derived from an ascidian voltage-gated ion channel superfamily. Unlike the previously reported omega-pore in the Shaker K + channel and rNav1.4, mutations are not required. From electrophysiological experiments in heterologous expression systems, we found that the conductance is directly mediated by the VSD itself and is carried by both monovalent and divalent cations. This is the first report of divalent cation permeation through a VSD-like structure. Copyright © 2018 Elsevier B.V. All rights reserved.

Intense predation on ascidians by a trunk fish, Ostracion immaculatus (Temminck et Schlege) (Pisces:Ostracidae)

Digital Repository Service at National Institute of Oceanography (India)

Raveendran, T.V.; Harada, E.

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Mollecarbamates, Molleureas, and Molledihydroisoquinolone, o-Carboxyphenethylamide Metabolites of the Ascidian Didemnum molle Collected in Madagascar.

Science.gov (United States)

Issac, Michal; Aknin, Maurice; Gauvin-Bialecki, Anne; Pond, Christopher D; Barrows, Louis R; Kashman, Yoel; Carmeli, Shmuel

2017-06-23

The extract of a sample of the tunicate Didemnum molle (MAY13-117) collected in Mayotte afforded eight new metabolites, mollecarbamates A-D (1-4) and molleureas B-E (5-8), along with the two known natural products, N,N'-diphenylethyl urea (10) and molleurea A (11). Another sample of D. molle (MAD11-BA065) collected in Baie des Assassins, Madagascar, afforded molledihydroisoquinolone (9). Mollecarbamates 1-4 are a family of compounds that possess repeating o-carboxyphenethylamide units and a carbamate moiety, while the molleureas 5-8 contain tetra- and penta-repeating carboxyphenethylamide units and a urea bridge in different positions. Molledihydroisoquinolone (9) is a cyclic form of o-carboxyphenethylamide. We propose that these unique natural products are most probably produced by an unprecedented biosynthetic pathway that contains a yet unknown chorismate mutase variant. The structures of the compounds were elucidated by interpretation of the data from 1D and 2D NMR, HRESIMS, and MS/MS analyses of the positive ESIMS experiments. Compounds 1-8 were tested against pathogenic bacteria and in a cytoprotective HIV cell based assay but did not show any significant effects in these assays.

Sexual and asexual reproduction in Didemnum rodriguesi (Ascidiacea, Didemnidae Reprodução sexuada e assexuada em Didemnum rodriguesi (Ascidiacea, Didemnidae

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Nicole F. Ritzmann

2009-03-01

Full Text Available Sexual and asexual reproduction and associated population dynamics were investigated in the colonial ascidian Didemnum rodriguesi Rocha & Monniot, 1993 (Didemnidae in southern Brazil. Investment in sexual (production of new individuals and asexual (colony growth reproduction was compared between seasons. Permanently marked quadrats were repeatedly photographed to measure changes in colonies. Eggs and larvae were counted monthly in collected colonies. This species alternates seasonally between sexual (summer and asexual (winter reproduction. In summer, colonies were smaller, brooded eggs and larvae and recruitment rates were greater, while in winter, colony size was larger and eggs and larvae were absent. There is a relationship between fecundity and colony area. Fragmentation and fusion of colonies were similar in summer and winter, as well as mortality. In conclusion, D. rodriguesi has a lifecycle usual for high latitude ascidians with a limited time length for sexual reproduction and alternate investment in sexual and asexual reproduction along the year.Reprodução sexuada e assexuada, mortalidade e a dinâmica de fusões e fissões de colônias de Didemnum rodriguesi Rocha & Monniot, 1993 foram investigados e comparados no sul do Brasil, no inverno e verão. Tais eventos foram analisados por fotografias de áreas permanentemente demarcadas e coletas mensais de colônias. Os resultados indicam que esta espécie alterna sazonalmente a reprodução sexuada (verão e assexuada (inverno. Durante o verão as colônias são mais abundantes e menores, com ovos e larvas incubados e taxas de recrutamento maiores. No inverno há um menor número de colônias, porém de maior tamanho e inférteis. Existe uma relação entre fecundidade e tamanho da colônia. Não foram encontradas diferenças estatísticas no número de eventos de fragmentação e fusão entre o verão e inverno, bem como para mortalidade. Conclui-se que esta espécie tem um ciclo de

Toxicity of organic compounds to marine invertebrate embryos and larvae: a comparison between the sea urchin embryogenesis bioassay and alternative test species.

Science.gov (United States)

Bellas, Juan; Beiras, Ricardo; Mariño-Balsa, José Carlos; Fernández, Nuria

2005-04-01

This study investigated the toxic effects of the insecticides lindane and chlorpyrifos, the herbicide diuron, the organometallic antifoulant tributyltin (TBT), and the surfactant sodium dodecyl sulfate (SDS) on the early life stages of Paracentrotus lividus (Echinodermata, Euechinoidea), Ciona intestinalis (Chordata, Ascidiacea), Maja squinado and Palaemon serratus (Arthropoda, Crustacea) in laboratory acute toxicity tests. The assays studied embryogenesis success from fertilized egg to normal larvae in P. lividus (48 h incubation at 20 degrees C) and C. intestinalis (24 h incubation at 20 degrees C), and larval mortality at 24 and 48 h in M. squinado and P. serratus. For P. lividus, the median effective concentrations (EC50) reducing percentages of normal larvae by 50% were: 350 microg l(-1) for chlorpyrifos, 5500 microg l(-1) for diuron, 4277 microg l(-1) for SDS, and 0.309 microg l(-1) for TBT. For C. intestinalis, the EC50 values affecting embryogenesis success were 5666 microg l(-1) for chlorpyrifos, 24,397 microg (l-1) for diuron, 4412 microg l(-1) for lindane, 5145 microg I(-1) for SDS, and 7.1 microg l(-1) for TBT. The median lethal concentrations (LC50) for M. squinado larval survival were 0.84 microg l(-1) (24 h) and 0.79 microg l(-1) (48 h) for chlorpyrifos, 2.23 microg(l(-1) (24 h) and 2.18 microg l(-1) (48 h) for lindane, and 687 microg l(-1) (48 h) for SDS. For P. serratus the LC50 values obtained were 0.35 microg l(-1) (24 h) and 0.22 microg l(-1) (48 h) for chlorpyrifos, 3011 microg l(-1) (24 h) and 3044 microg l(-1) (48 h) for diuron, 5.20 microg l(-1) (24 h) and 5.59 microg l(-1) (48 h) for lindane, and 22.30 microg l(-1) (24 h) and 17.52 microg l(-1) (48 h) for TBT. Decapod larvae, as expected, were markedly more sensitive to the insecticides than sea urchins and ascidians, and SDS was the least toxic compound tested for these organisms. Lowest observed effect concentrations (LOEC) of TBT for sea urchin and ascidian embryos, chlorpyrifos and

Biofouling community pattern on various metallic surfaces in the coastal waters of Kalpakkam, Southwestern Bay of Bengal

International Nuclear Information System (INIS)

Sahu, Gouri; Satpathy, K.K.; Mohanty, A.K.; Bindu, V.K.

2015-01-01

. 100 cm -2 . The major fouling organisms such as, barnacle, green mussel and ascidian constituted ∼ 70-80% of the total fouling. In the present study, sequence of fouling succession was as follows, barnacle - hydroid - sea anemone - ascidian and finally green mussel (Perna viridis Linn. 1758). The paper also discusses species diversity indices (diversity, richness and evenness) in detail. (author)

Characteristics of the mesophotic megabenthic assemblages of the vercelli seamount (north tyrrhenian sea.

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Marzia Bo

2011-02-01

Full Text Available The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount is described using Remotely Operated Vehicle (ROV video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i the top shows a dense covering of the kelp Laminaria rodriguezii; (ii the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.

3D-printed microwell arrays for Ciona microinjection and timelapse imaging.

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Clint Gregory

Full Text Available Ascidians such as Ciona are close chordate relatives of the vertebrates with small, simple embryonic body plans and small, simple genomes. The tractable size of the embryo offers considerable advantages for in toto imaging and quantitative analysis of morphogenesis. For functional studies, Ciona eggs are considerably more challenging to microinject than the much larger eggs of other model organisms such as zebrafish and Xenopus. One of the key difficulties is in restraining the eggs so that the microinjection needle can be easily introduced and withdrawn. Here we develop and test a device to cast wells in agarose that are each sized to hold a single egg. This injection mold is fabricated by micro-resolution stereolithography with a grid of egg-sized posts that cast corresponding wells in agarose. This 3D printing technology allows the rapid and inexpensive testing of iteratively refined prototypes. In addition to their utility in microinjection, these grids of embryo-sized wells are also valuable for timelapse imaging of multiple embryos.

Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Müller, 1776 and Clavelina phlegraea (Salfi, 1929 (Tunicata, Ascidiacea

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R Pennati

2009-08-01

Full Text Available Almost all ascidian larvae bear three mucus secreting and sensory organs, the adhesive papillae, at the anterior end of the trunk, which play an important role during the settlement phase. The morphology and the cellular composition of these organs varies greatly in the different species. The larvae of the Clavelina genus bear simple bulbous papillae, which are considered to have only a secretory function. We analysed the adhesive papillae of two species belonging to this genus, C. lepadiformis and C. phlegraea, by histological sections and by immunolocalisation of b-tubulin and serotonin, in order to better clarify the cellular composition of these organs.We demonstrated that they contain at least two types of neurons: central neurons, bearing microvilli, and peripheral ciliated neurons. Peripheral neurons of C. lepadiformis contain serotonin. We suggest that these two neurons play different roles during settlement: the central ones may be chemo- or mechanoreceptors that sense the substratum, and the peripheral ones may be involved in the mechanism that triggers metamorphosis.

Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Müller, 1776 and Clavelina phlegraea (Salfi, 1929 (Tunicata, Ascidiacea

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G Zega

2009-03-01

Full Text Available Almost all ascidian larvae bear three mucus secreting and sensory organs, the adhesive papillae, at the anterior end of the trunk, which play an important role during the settlement phase. The morphology and the cellular composition of these organs varies greatly in the different species. The larvae of the Clavelina genus bear simple bulbous papillae, which are considered to have only a secretory function. We analysed the adhesive papillae of two species belonging to this genus, C. lepadiformis and C. phlegraea, by histological sections and by immunolocalisation of b-tubulin and serotonin, in order to better clarify the cellular composition of these organs.We demonstrated that they contain at least two types of neurons: central neurons, bearing microvilli, and peripheral ciliated neurons. Peripheral neurons of C. lepadiformis contain serotonin. We suggest that these two neurons play different roles during settlement: the central ones may be chemo- or mechanoreceptors that sense the substratum, and the peripheral ones may be involved in the mechanism that triggers metamorphosis.

Ancient deuterostome origins of vertebrate brain signalling centres.

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Pani, Ariel M; Mullarkey, Erin E; Aronowicz, Jochanan; Assimacopoulos, Stavroula; Grove, Elizabeth A; Lowe, Christopher J

2012-03-14

Neuroectodermal signalling centres induce and pattern many novel vertebrate brain structures but are absent, or divergent, in invertebrate chordates. This has led to the idea that signalling-centre genetic programs were first assembled in stem vertebrates and potentially drove morphological innovations of the brain. However, this scenario presumes that extant cephalochordates accurately represent ancestral chordate characters, which has not been tested using close chordate outgroups. Here we report that genetic programs homologous to three vertebrate signalling centres-the anterior neural ridge, zona limitans intrathalamica and isthmic organizer-are present in the hemichordate Saccoglossus kowalevskii. Fgf8/17/18 (a single gene homologous to vertebrate Fgf8, Fgf17 and Fgf18), sfrp1/5, hh and wnt1 are expressed in vertebrate-like arrangements in hemichordate ectoderm, and homologous genetic mechanisms regulate ectodermal patterning in both animals. We propose that these genetic programs were components of an unexpectedly complex, ancient genetic regulatory scaffold for deuterostome body patterning that degenerated in amphioxus and ascidians, but was retained to pattern divergent structures in hemichordates and vertebrates. © 2012 Macmillan Publishers Limited. All rights reserved

Larval abundance and its relation to macrofouling settlement pattern in the coastal waters of Kalpakkam, southeastern part of India.

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Sahu, Gouri; Satpathy, K K; Mohanty, A K; Biswas, Sudeepta; Achary, M Smita; Sarkar, S K

2013-02-01

The present work revealed that salinity, water temperature, and food availability were the most crucial factors affecting the abundance of larvae and their settlement as macrofouling community in the coastal waters of Kalpakkam. Quantitative as well as qualitative results showed that late post-monsoon (April-May) and pre-monsoon (June-September) periods were found to be suitable periods for larval growth, development, and survival to adult stages for most of the organisms. Clustering of physico-chemical and biological (including larval and adult availability) data yielded two major clusters; one formed by northeast (NE) monsoon months (October-January) and the other by post-monsoon/summer (February-May) months, whereas; pre-monsoon months (June-September) were distributed between these two clusters. Among all the major macrofouler groups, only bivalves established a successful relationship between its larval abundance and adult settlement. Principal component analysis indicated good associations of bivalve larvae with polychaete larvae and adult bivalves with adult barnacles. However, biotic relation between ascidians and bryozoans was observed both in the larval as well as adult community.

Sitotoksisitas Invertebrata Laut sebagai Biomarker Lingkungan Di Kawasan Konservasi Perairan Pulau Banda

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Asri Pratitis

2017-05-01

Full Text Available Penelitian di bidang ekologi menunjukkan bahwa wilayah terumbu karang yang terjaga denganbaik oleh konservasi menjadi tempat yang ideal bagi biota invertebrata untuk menghasilkansenyawa bioaktif farmakologis. Penelitian ini bertujuan memperoleh informasi mengenaisitotoksisitas dari spons, karang lunak dan ascidian yang berasal dari perairan Pulau Banda. Informasi sitotoksisitas invertebrata laut tersebut selanjutnya digunakan sebagai acuan dalammempelajari sistem konservasi yang telah dilakukan. Lima jenis invertebrata laut (Sarcophyton sp., Nephthea sp., Hyrtios sp., Stylissa sp., dan Polycarpa sp. diambil (lima ulangan acak di kawasan konservasi Pantai Wali, Desa Solomon, Pulau Banda. Penapisan sitotoksisitas dilakukan terhadap ekstrak etanol dari keseluruhan sampel. Hasil penapisan memperlihatkan bahwa  Stylissa sp. merupakan biota yang paling potensial karena ekstrak etanol dari  Stylissa sp. memiliki daya sitotoksisitas tertinggi dibandingkan jenis invertebrata yang diujikan lainnya. Namun demikian, sitotoksisitas biota-biota yang diperoleh dari perairan ini tergolong rendah.Perbandingan multidimensional scaling(MDS nilai sitotoksisitas antara sampel invertebratadari perairan Banda dan perairan lainnya menunjukkan bahwa karakteristik perairan Pulau Banda berada pada level baik dan rendah. Oleh karena itu, sistem konservasi harus dioptimasi lebihlanjut agar dapat menjaga keberlangsungan plasma nutfah di perairan Pulau Banda.

Microfilament Contraction Promotes Rounding of Tunic Slices: An Integumentary Defense System in the Colonial Ascidian Aplidium yamazii.

Science.gov (United States)

Hirose, E; Ishii, T

1995-08-01

In Aplidium yamazii, when a slice of a live colony (approximately 0.5 mm thick) was incubated in seawater for 12 h, the slice became a round tunic fragment. This tunic rounding was inhibited by freezing of the slices, incubation with Ca2+-Mg2+ -free seawater, or addition of cytochalasin B. Staining of microfilaments in the slices with phalloidin-FITC showed the existence of a cellular network in the tunic. Contraction of this cellular network probably promotes rounding of the tunic slice. In electron microscopic observations, a new tunic cuticle regenerated at the surface of the round tunic fragments; the tunic cuticle did not regenerate in newly sliced specimens nor in specimens in which rounding was experimentally inhibited. Based on these results, an integumentary defense system is proposed in this species as follows. (1) When the colony is wounded externally, contraction of the cellular network promotes tunic contraction around the wound. (2) The wound is almost closed by tunic contraction. (3) Tunic contraction increases the density of the filamentous components of the tunic at the wound, and it may accelerate the regeneration of tunic cuticle there.

Epibiosis of oxygen phototrophs containing chlorophylls a, b, c, and d on the colonial ascidian Cystodytes dellechiajei

Czech Academy of Sciences Publication Activity Database

Martínez-García, M.; Koblížek, Michal; López-Legentil, S.; Antón, J.

2011-01-01

Roč. 61, č. 1 (2011), s. 13-19 ISSN 0095-3628 Institutional research plan: CEZ:AV0Z50200510 Keywords : D-PRODUCING CYANOBACTERIUM * ACARYOCHLORIS-MARINA * ADAPTATION Subject RIV: EE - Microbiology, Virology Impact factor: 2.912, year: 2011

Water-borne sperm trigger vitellogenic egg growth in two sessile marine invertebrates.

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Bishop, J D; Manríquez, P H; Hughes, R N

2000-06-22

A diverse array of sessile marine invertebrates mate by passive dispersal of sperm which fertilize the brooded eggs of neighbours. In two such species, a sea-mat (phylum Bryozoa) and an ascidian (phylum Chordata), vitellogenic egg growth is absent in reproductively isolated specimens, but is triggered by a water-borne factor released by conspecifics. In both of these colonial, hermaphroditic species, the active factor can be removed from water by filtration. The effect involves self-/non-self-recognition: water conditioned by a separate subcolony of the same genetic individual does not prompt oocyte growth. In each species, allosperm move from the surrounding water to the ovary and are then stored in close association with the growing oocytes. We concluded that sperm themselves are the water-borne factor that triggers the major phase of female reproductive investment. This mechanism is, to our knowledge, previously undescribed in animals, but has parallels with the initiation of maternal investment in flowering plants following the receipt of compatible pollen. The species studied may be representative of many other aquatic invertebrates which mate in a similar way. The stimulation of egg growth by allosperm could lead to intersexual conflict during oogenesis.

Life in the colonies: learning the alien ways of colonial organisms.

Science.gov (United States)

Winston, Judith E

2010-12-01

Who needs to go to outer space to study alien beings when the oceans of our own planet abound with bizarre and unknown creatures? Many of them belong to sessile clonal and colonial groups, including sponges, hydroids, corals, octocorals, ascidians, bryozoans, and some polychaetes. Their life histories, in many ways unlike our own, are a challenge for biologists. Studying their ecology, behavior, and taxonomy means trying to “think like a colony” to understand the factors important in their lives. Until the 1980s, most marine ecologists ignored these difficult modular organisms. Plant ecologists showed them ways to deal with the two levels of asexually produced modules and genetic individuals, leading to a surge in research on the ecology of clonal and colonial marine invertebrates. Bryozoans make excellent model colonial animals. Their life histories range from ephemeral to perennial. Aspects of their lives such as growth, reproduction, partial mortality due to predation or fouling, and the behavior of both autozooids and polymorphs can be studied at the level of the colony, as well as that of the individual module, in living colonies and over time.

Transforming growth factor β (CiTGF-β) gene expression is induced in the inflammatory reaction of Ciona intestinalis.

Science.gov (United States)

Vizzini, Aiti; Di Falco, Felicia; Parrinello, Daniela; Sanfratello, Maria Antonietta; Cammarata, Matteo

2016-02-01

Transforming growth factor (TGF-β) is a well-known component of a regulatory cytokines superfamily that has pleiotropic functions in a broad range of cell types and is involved, in vertebrates, in numerous physiological and pathological processes. In the current study, we report on Ciona intestinalis molecular characterisation and expression of a transforming growth factor β homologue (CiTGF-β). The gene organisation, phylogenetic tree and modelling supported the close relationship with the mammalian TGF suggesting that the C. intestinalis TGF-β gene shares a common ancestor in the chordate lineages. Functionally, real-time PCR analysis showed that CiTGF-β was transcriptionally upregulated in the inflammatory process induced by LPS inoculation, suggesting that is involved in the first phase and significant in the secondary phase of the inflammatory response in which cell differentiation occurs. In situ hybridisation assays revealed that the genes transcription was upregulated in the pharynx, the main organ of the ascidian immune system, and expressed by cluster of hemocytes inside the pharynx vessels. These data supported the view that CiTGF-β is a potential molecule in immune defence systems against bacterial infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Contribution to the knowledge of cotylean flatworms (Turbellaria, Polycladida) from Iranian coasts: Introducing a new species, with remarks on new records.

Science.gov (United States)

Maghsoudlou, Abdolvahab; Rahimian, Hassan

2014-09-08

Very little information is available regarding marine free-living flatworms not only from Iran, but throughout the countries surrounding the Persian Gulf and the Gulf of Oman. The present study first introduces a new euryleptid species, and then reports four pseudocerotid polyclads which inhabit Iranian shallow rocky shores of the Persian Gulf and the Gulf of Oman. Maritigrella makranica sp. nov. is characterized dorsally by a medial cream or white reticulated appearance containing pale orange spots in a honeycomb pattern, a distinct orange submarginal band around the entire body margin and between the marginal tentacles, black spots scattered around mid-dorsal surface, becoming more sparse on raised median region and towards body margin, surrounded by a dark-grey halo around the body midline and orange-black halo towards margin. Three of the four pseudocerotids species belonging to the genera Pseudobiceros Faubel, 1984; Pseudoceros Lang, 1884; and Thysanozoon Grube, 1840, are new records for the studied areas, while the other has been reported in the Persian Gulf previously. Comments on Iranian species are provided and associations of flatworms with ascidians and sponges were observed. 

Regulation of notochord-specific expression of Ci-Bra downstream genes in Ciona intestinalis embryos.

Science.gov (United States)

Takahashi, Hiroki; Hotta, Kohji; Takagi, Chiyo; Ueno, Naoto; Satoh, Nori; Shoguchi, Eiichi

2010-02-01

Brachyury, a T-box transcription factor, is expressed in ascidian embryos exclusively in primordial notochord cells and plays a pivotal role in differentiation of notochord cells. Previously, we identified approximately 450 genes downstream of Ciona intestinalis Brachyury (Ci-Bra), and characterized the expression profiles of 45 of these in differentiating notochord cells. In this study, we looked for cisregulatory sequences in minimal enhancers of 20 Ci-Bra downstream genes by electroporating region within approximately 3 kb upstream of each gene fused with lacZ. Eight of the 20 reporters were expressed in notochord cells. The minimal enchancer for each of these eight genes was narrowed to a region approximately 0.5-1.0-kb long. We also explored the genome-wide and coordinate regulation of 43 Ci-Bra-downstream genes. When we determined their chromosomal localization, it became evident that they are not clustered in a given region of the genome, but rather distributed evenly over 13 of the 14 pairs of chromosomes, suggesting that gene clustering does not contribute to coordinate control of the Ci-Bra downstream gene expression. Our results might provide Insights Into the molecular mechanisms underlying notochord formation in chordates.

Ciona intestinalis Noto4 contains a phosphotyrosine interaction domain and is involved in the midline intercalation of notochord cells.

Science.gov (United States)

Yamada, Shigehiro; Ueno, Naoto; Satoh, Nori; Takahashi, Hiroki

2011-01-01

Brachyury plays a pivotal role in the notochord formation in ascidian embryos. Ciona intestinalis Noto4 (Ci-Noto4) was isolated as a gene downstream of Ci-Bra. This gene encodes a 307 amino-acid protein with a C-terminal phosphotyrosine interaction domain (PTB/PID). Expression of Ci-Noto4 commences at the neural plate stage and is specific to notochord cells. Suppression of Ci-Noto4 levels with specific antisense morpholino oligonucleotides resulted in the formation of two rows of notochord cells owing to a lack of midline intercalation between the bilateral populations of progenitor cells. In contrast, overexpression of Ci-Noto4 by injection of a Ci-Bra(promoter):Ci-Noto4-EGFP construct into fertilized eggs disrupted the localization of notochord cells. Ci-Noto4 overexpression did not affect cellular differentiation in the notochord, muscle, mesenchyme, or nervous system. Analysis of Ci-Noto4 regions that are responsible for its function suggested significant roles for the PTB/PID and a central region, an area with no obvious sequence similarity to other known proteins. These results suggested that PTB/PID-containing Ci-Noto4 is essential for midline intercalation of notochord cells in chordate embryos.

Functional and evolutionary insights from the Ciona notochord transcriptome.

Science.gov (United States)

Reeves, Wendy M; Wu, Yuye; Harder, Matthew J; Veeman, Michael T

2017-09-15

The notochord of the ascidian Ciona consists of only 40 cells, and is a longstanding model for studying organogenesis in a small, simple embryo. Here, we perform RNAseq on flow-sorted notochord cells from multiple stages to define a comprehensive Ciona notochord transcriptome. We identify 1364 genes with enriched expression and extensively validate the results by in situ hybridization. These genes are highly enriched for Gene Ontology terms related to the extracellular matrix, cell adhesion and cytoskeleton. Orthologs of 112 of the Ciona notochord genes have known notochord expression in vertebrates, more than twice as many as predicted by chance alone. This set of putative effector genes with notochord expression conserved from tunicates to vertebrates will be invaluable for testing hypotheses about notochord evolution. The full set of Ciona notochord genes provides a foundation for systems-level studies of notochord gene regulation and morphogenesis. We find only modest overlap between this set of notochord-enriched transcripts and the genes upregulated by ectopic expression of the key notochord transcription factor Brachyury, indicating that Brachyury is not a notochord master regulator gene as strictly defined. © 2017. Published by The Company of Biologists Ltd.

A novel mutation (C1425Y) in the FBN2 gene in a father and son with congenital contractural arachnodactyly.

Science.gov (United States)

Chen, Ying; Lei, Yun-Ping; Zheng, Hong-Xiang; Wang, Wei; Cheng, Hong-Bo; Zhang, Jing; Wang, Hong-Yan; Jin, Li; Li, Hong

2009-06-01

Congenital contractural arachnodactyly (Beals syndrome) is a rare autosomal dominantly inherited connective tissue disorder characterized by flexion contractures, arachnodactyly, crumpled ears, and mild muscular hypoplasia. Here, a father and son with congenital contractural arachnodactyly features were identified. After sequencing 15 exons (22 to 36) of the FBN2 gene, a novel mutation (C1425Y) was found in exon 33. This de novo mutation presented first in the father and was transmitted to his son, but not in the other 14 unaffected family members and 365 normal people. The C1425Y mutation occurs at the 19th cbEGF domain. Cysteines in this cbEGF domain are rather conserved in species, from human down to ascidian. The cbEGF12-13 in human FBN1 was employed as the template to perform homology modeling of cbEGF18-19 of human FBN2 protein. The mutation has also been evaluated by further prediction tools, for example, SIFT, Blosum62, biochemical Yu's matrice, and UMD-Predictor tool. In all analysis, the mutation is predicted to be pathogenic. Thus, the structure destabilization by C1425Y might be the cause of the disorder.

The cult of amphioxus in German Darwinism; or, our gelatinous ancestors in Naples' blue and balmy bay.

Science.gov (United States)

Hopwood, Nick

2015-01-01

Biologists having rediscovered amphioxus, also known as the lancelet or Branchiostoma, it is time to reassess its place in early Darwinist debates over vertebrate origins. While the advent of the ascidian-amphioxus theory and challenges from various competitors have been, documented, this article offers a richer account of the public appeal of amphioxus as a primitive ancestor. The focus is on how the 'German Darwin' Ernst Haeckel persuaded general magazine and newspaper readers to revere this "flesh of our flesh and blood of our blood", and especially on Das neue Laienbrevier des Haeckelismus (The new lay breviary of Haeckelism) by Moritz Reymond with cartoons by Fritz Steub. From the late 1870s these successful little books of verse introduced the Neapolitan discoveries that made the animal's name and satirized Haeckel's rise as high priest of its cult. One song is reproduced and translated here, with a contemporary "imitation" by the Canadian palaeontologist Edward John Chapman, and extracts from others. Predating the American "It's a long way from amphioxus" by decades, these rhymes dramatize neglected 'species politics' of Darwinism and highlight the roles of humour in negotiating evolution.

Trabectedin for Soft Tissue Sarcoma: Current Status and Future Perspectives.

Science.gov (United States)

Gordon, Erlinda M; Sankhala, K Kumar; Chawla, Neal; Chawla, Sant P

2016-07-01

Trabectedin (ET743, Yondelis(®), manufactured by Baxter Oncology GmbH, Halle/Westfalen, Germany, for Janssen Products, LP, Horsham, PA), derived from the marine ascidian, Ecteinascidia turbinata, is a natural alkaloid with multiple complex mechanisms of action. On 23 October 2015, 15 years after the results of the first Phase 1 clinical trial using trabectedin for chemotherapy-resistant solid malignancies was reported, and 8 years after its approval in Europe, the United States Food and Drug Administration (USFDA) finally approved trabectedin for the treatment of unresectable or metastatic liposarcoma or leiomyosarcoma that has failed a prior anthracycline-containing regimen. Approval was based on the results of a pivotal Phase 3 trial involving a 2:1 randomization of 518 patients (who were further stratified by soft tissue sarcoma subtype), in which a significant improvement in progression-free survival was reported in the trabectedin-treated group vs. the dacarbazine-treated group (p concept. In short, trabectedin is an old new drug with proven potential to impact the lives of patients with soft tissue sarcoma and other solid malignancies. Sarcoma Oncology Center, Santa Monica, CA 90405.

Mandelalides A-D, cytotoxic macrolides from a new Lissoclinum species of South African tunicate.

Science.gov (United States)

Sikorska, Justyna; Hau, Andrew M; Anklin, Clemens; Parker-Nance, Shirley; Davies-Coleman, Michael T; Ishmael, Jane E; McPhail, Kerry L

2012-07-20

Mandelalides A-D are variously glycosylated, unusual polyketide macrolides isolated from a new species of Lissoclinum ascidian collected from South Africa, Algoa Bay near Port Elizabeth and the surrounding Nelson Mandela Metropole. Their planar structures were elucidated on submilligram samples by comprehensive analysis of 1D and 2D NMR data, supported by mass spectrometry. The assignment of relative configuration was accomplished by consideration of homonuclear and heteronuclear coupling constants in tandem with ROESY data. The absolute configuration was assigned for mandelalide A after chiral GC-MS analysis of the hydrolyzed monosaccharide (2-O-methyl-α-L-rhamnose) and consideration of ROESY correlations between the monosaccharide and aglycone in the intact natural product. The resultant absolute configuration of the mandelalide A macrolide was extrapolated to propose the absolute configurations of mandelalides B-D. Remarkably, mandelalide B contained the C-4' epimeric 2-O-methyl-6-dehydro-α-L-talose. Mandelalides A and B showed potent cytotoxicity to human NCI-H460 lung cancer cells (IC(50), 12 and 44 nM, respectively) and mouse Neuro-2A neuroblastoma cells (IC(50), 29 and 84 nM, respectively).

Differential temporal control of Foxa.a and Zic-r.b specifies brain versus notochord fate in the ascidian embryo.

Science.gov (United States)

Ikeda, Tatsuro; Satou, Yutaka

2017-01-01

In embryos of an invertebrate chordate, Ciona intestinalis, two transcription factors, Foxa.a and Zic-r.b, are required for specification of the brain and the notochord, which are derived from distinct cell lineages. In the brain lineage, Foxa.a and Zic-r.b are expressed with no temporal overlap. In the notochord lineage, Foxa.a and Zic-r.b are expressed simultaneously. In the present study, we found that the temporally non-overlapping expression of Foxa.a and Zic-r.b in the brain lineage was regulated by three repressors: Prdm1-r.a (formerly called BZ1), Prdm1-r.b (BZ2) and Hes.a. In morphant embryos of these three repressor genes, Foxa.a expression was not terminated at the normal time, and Zic-r.b was precociously expressed. Consequently, Foxa.a and Zic-r.b were expressed simultaneously, which led to ectopic activation of Brachyury and its downstream pathways for notochord differentiation. Thus, temporal controls by transcriptional repressors are essential for specification of the two distinct fates of brain and notochord by Foxa.a and Zic-r.b Such a mechanism might enable the repeated use of a limited repertoire of transcription factors in developmental gene regulatory networks. © 2017. Published by The Company of Biologists Ltd.

Characterization and metal-induced gene transcription of two new copper zinc superoxide dismutases in the solitary ascidian Ciona intestinalis

International Nuclear Information System (INIS)

Ferro, Diana; Franchi, Nicola; Mangano, Valentina; Bakiu, Rigers; Cammarata, Matteo; Parrinello, Nicolò; Santovito, Gianfranco; Ballarin, Loriano

2013-01-01

Highlights: •Ciona intestinalis express two copper-zinc superoxide dismutases (Cu,Zn SODs), one extracellular (Ci-SODa) and one intracellular isoform (Ci-SODb). •Promoters contain consensus sequences similar to mammalian MRE. •Metal exposure results in a significant increase of gene transcription: ci-soda is induced especially by copper and zinc, the increase of ci-sodb transcription is more evident after cadmium exposure. •Genes are mostly transcribed in circulating hemocytes and in ovarian follicular cells. -- Abstract: Antioxidant enzymes are known to protect living organisms against the oxidative stress risk, also induced by metals. In the present study, we describe the purification and molecular characterization of two Cu,Zn superoxide dismutases (SODs), referred to as Ci-SODa and Ci-SODb, from Ciona intestinalis, a basal chordate widely distributed in temperate shallow seawater. The putative amino acid sequences were compared with Cu,Zn SODs from other metazoans and phylogenetic analyses indicate that the two putative Ci-SODs are more related to invertebrate SODs than vertebrate ones. Both phylogenetic and preliminary homology modeling analyses suggest that Ci-SODa and Ci-SODb are extracellular and intracellular isoform, respectively. The mRNA of the two Cu,Zn SODs was localized in hemocytes and in ovarian follicular cells, as revealed by in situ hybridization. The time course of SOD mRNA levels in the presence of three different metals showed upregulation of ci-soda and inhibition of ci-sodb. Spectrophotometric analysis confirms the presence of SOD activity in Ciona tissues. Our in silico analyses of the ci-soda promoter region revealed putative consensus sequences similar to mammalian metal-responsive elements (MRE), suggesting that the transcription of these genes directly depends on metals. These data emphasize the importance of complex metal regulation of ci-soda and ci-sodb transcription, as components of an efficient detoxification pathway allowing the survival of C. intestinalis in continued, elevated presence of metals in the environment

Characterization and metal-induced gene transcription of two new copper zinc superoxide dismutases in the solitary ascidian Ciona intestinalis

Energy Technology Data Exchange (ETDEWEB)

Ferro, Diana [Department of Biology, University of Padova, Padova (Italy); Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität, Münster (Germany); Franchi, Nicola [Department of Biology, University of Padova, Padova (Italy); Department of Biological, Chemical, Pharmaceutical Science and Technology, University of Palermo, Palermo (Italy); Mangano, Valentina [Department of Biological, Chemical, Pharmaceutical Science and Technology, University of Palermo, Palermo (Italy); Bakiu, Rigers [Department of Crop Production, Agricultural University of Tirana, Tirana (Albania); Cammarata, Matteo; Parrinello, Nicolò [Department of Biological, Chemical, Pharmaceutical Science and Technology, University of Palermo, Palermo (Italy); Santovito, Gianfranco, E-mail: gianfranco.santovito@unipd.it [Department of Biology, University of Padova, Padova (Italy); Ballarin, Loriano [Department of Biology, University of Padova, Padova (Italy)

2013-09-15

Highlights: •Ciona intestinalis express two copper-zinc superoxide dismutases (Cu,Zn SODs), one extracellular (Ci-SODa) and one intracellular isoform (Ci-SODb). •Promoters contain consensus sequences similar to mammalian MRE. •Metal exposure results in a significant increase of gene transcription: ci-soda is induced especially by copper and zinc, the increase of ci-sodb transcription is more evident after cadmium exposure. •Genes are mostly transcribed in circulating hemocytes and in ovarian follicular cells. -- Abstract: Antioxidant enzymes are known to protect living organisms against the oxidative stress risk, also induced by metals. In the present study, we describe the purification and molecular characterization of two Cu,Zn superoxide dismutases (SODs), referred to as Ci-SODa and Ci-SODb, from Ciona intestinalis, a basal chordate widely distributed in temperate shallow seawater. The putative amino acid sequences were compared with Cu,Zn SODs from other metazoans and phylogenetic analyses indicate that the two putative Ci-SODs are more related to invertebrate SODs than vertebrate ones. Both phylogenetic and preliminary homology modeling analyses suggest that Ci-SODa and Ci-SODb are extracellular and intracellular isoform, respectively. The mRNA of the two Cu,Zn SODs was localized in hemocytes and in ovarian follicular cells, as revealed by in situ hybridization. The time course of SOD mRNA levels in the presence of three different metals showed upregulation of ci-soda and inhibition of ci-sodb. Spectrophotometric analysis confirms the presence of SOD activity in Ciona tissues. Our in silico analyses of the ci-soda promoter region revealed putative consensus sequences similar to mammalian metal-responsive elements (MRE), suggesting that the transcription of these genes directly depends on metals. These data emphasize the importance of complex metal regulation of ci-soda and ci-sodb transcription, as components of an efficient detoxification pathway allowing the survival of C. intestinalis in continued, elevated presence of metals in the environment.

Functional Brachyury binding sites establish a temporal read-out of gene expression in the Ciona notochord.

Directory of Open Access Journals (Sweden)

Lavanya Katikala

2013-10-01

Full Text Available The appearance of the notochord represented a milestone in Deuterostome evolution. The notochord is necessary for the development of the chordate body plan and for the formation of the vertebral column and numerous organs. It is known that the transcription factor Brachyury is required for notochord formation in all chordates, and that it controls transcription of a large number of target genes. However, studies of the structure of the cis-regulatory modules (CRMs through which this control is exerted are complicated in vertebrates by the genomic complexity and the pan-mesodermal expression territory of Brachyury. We used the ascidian Ciona, in which the single-copy Brachyury is notochord-specific and CRMs are easily identifiable, to carry out a systematic characterization of Brachyury-downstream notochord CRMs. We found that Ciona Brachyury (Ci-Bra controls most of its targets directly, through non-palindromic binding sites that function either synergistically or individually to activate early- and middle-onset genes, respectively, while late-onset target CRMs are controlled indirectly, via transcriptional intermediaries. These results illustrate how a transcriptional regulator can efficiently shape a shallow gene regulatory network into a multi-tiered transcriptional output, and provide insights into the mechanisms that establish temporal read-outs of gene expression in a fast-developing chordate embryo.

Fixation, description and DNA barcode of a neotype for Botryllus schlosseri (Pallas, 1766) (Tunicata, Ascidiacea).

Science.gov (United States)

Brunetti, Riccardo; Manni, Lucia; Mastrototaro, Francesco; Gissi, Carmela; Gasparini, Fabio

2017-11-22

Botryllus schlosseri is a widespread colonial ascidian commonly considered cosmopolitan and amply used as model for researches ranging from developmental biology to immunobiology. Recently, molecular data lead to hypothesize that the species named B. schlosseri may consist of more than a single taxon. Indeed, five highly divergent clades, named A-E, have been genetically identified and are referred as cryptic species. In this context, and lacking both a type and a detailed morphological description, we believe that it is necessary, as a taxonomic reference point, to designate a neotype and re-describe the species. Therefore, a sample from the Lagoon of Venice (Adriatic Sea, Italy) was deposited as neotype in the Natural History Museum of Venice (Italy), preserved both in formalin and in 90% ethanol. Here we provide a morphological description of the suggested neotype of B. schlosseri that takes into account several developmental stages (oozooid, zooid of first blastogenic generations, and mature zooid) and is carefully compared with the previous descriptions of samples coming from other European and non-European localities. Finally, we associate our morphological description to a "DNA barcode", consisting in a long fragment of the mitochondrial COI gene. Our description is associated to clade A, although at now we cannot guarantee that this association is univocal.

Biodiversity of shallow subtidal, under-rock invertebrates in Europe's first marine reserve: Effects of physical factors and scientific sampling

Science.gov (United States)

Trowbridge, Cynthia D.; Kachmarik, Katy; Plowman, Caitlin Q.; Little, Colin; Stirling, Penny; McAllen, Rob

2017-03-01

At Lough Hyne Marine Reserve in SW Ireland, shallow subtidal, under-rock biodiversity was investigated to assess (i) any deleterious effects of scientific sampling and (ii) quantitative baseline community patterns. Comparisons were made between 10 sites with annual rock-turning disturbance and 10 with multi-decadal (historical) disturbance. At each site, shallow subtidal rocks (N = 1289 total) were lifted, organisms recorded, and rocks replaced in their original position. Biodiversity indices were calculated to evaluate how diversity varied with location within the lough, frequency of sampling disturbance, degree of hypoxia/anoxia, dissolved oxygen (DO) concentration, and number of rocks turned. The richness of solitary invertebrates surveyed in situ averaged 21 taxa per site with significantly more in the South Basin (near the lough's connection to the ocean) than in the North Basin. The Shannon-Wiener Index did not differ significantly with variables investigated. However, evenness was higher at annually disturbed sites than at historical ones where anemones with algal symbionts often dominated. Several sites were hypoxic to anoxic under the shallow subtidal rocks. Cup corals were most abundant in the South Basin; DO was a crucial explanatory variable of these sensitive species. Solitary ascidians were most abundant at South-Basin annual sites with DO levels being a highly significant explanatory variable.

Genetic Compatibility Underlies Benefits of Mate Choice in an External Fertilizer.

Science.gov (United States)

Aguirre, J David; Blows, Mark W; Marshall, Dustin J

2016-05-01

Mate choice is a common feature of sexually reproducing species. In sessile or sedentary external fertilizers, however, direct interactions between reproductive partners are minimal, and instead mate recognition and choice must occur at the level of gametes. It is common for some sperm and egg combinations to have higher fertilization success than others, but it remains unclear whether differences in fertilization reflect gamete-level mate choice (GMC) for paternal quality or parental compatibility. Here, we examine the mechanisms underlying GMC in an externally fertilizing ascidian. A manipulative mate-choice assay confirmed that offspring viability was greater in clutches where we allowed GMC than in clutches where we precluded GMC. A complementary quantitative genetic experiment then revealed that paternal quality effects were generally weaker than parental compatibility effects, particularly for the trait combination underlying the benefits of GMC. Overall, our data suggest that gametes that are more compatible at fertilization produce more viable offspring than gametes that are less compatible at fertilization. Therefore, although the regalia we typically associate with sexual selection are absent in external fertilizers, mechanisms that allow females to bias fertilization in favor of some males over others produce significant fitness benefits in organisms reproducing via the ancestral strategy.

δ13C and δ15N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica

International Nuclear Information System (INIS)

Conlan, Kathleen E. . E-mail kconlan@mus-nature.ca; Rau, Greg H.; Kvitek, Rikk G.

2006-01-01

In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic

Functional Brachyury binding sites establish a temporal read-out of gene expression in the Ciona notochord.

Science.gov (United States)

Katikala, Lavanya; Aihara, Hitoshi; Passamaneck, Yale J; Gazdoiu, Stefan; José-Edwards, Diana S; Kugler, Jamie E; Oda-Ishii, Izumi; Imai, Janice H; Nibu, Yutaka; Di Gregorio, Anna

2013-10-01

The appearance of the notochord represented a milestone in Deuterostome evolution. The notochord is necessary for the development of the chordate body plan and for the formation of the vertebral column and numerous organs. It is known that the transcription factor Brachyury is required for notochord formation in all chordates, and that it controls transcription of a large number of target genes. However, studies of the structure of the cis-regulatory modules (CRMs) through which this control is exerted are complicated in vertebrates by the genomic complexity and the pan-mesodermal expression territory of Brachyury. We used the ascidian Ciona, in which the single-copy Brachyury is notochord-specific and CRMs are easily identifiable, to carry out a systematic characterization of Brachyury-downstream notochord CRMs. We found that Ciona Brachyury (Ci-Bra) controls most of its targets directly, through non-palindromic binding sites that function either synergistically or individually to activate early- and middle-onset genes, respectively, while late-onset target CRMs are controlled indirectly, via transcriptional intermediaries. These results illustrate how a transcriptional regulator can efficiently shape a shallow gene regulatory network into a multi-tiered transcriptional output, and provide insights into the mechanisms that establish temporal read-outs of gene expression in a fast-developing chordate embryo.

Cyanobacteria in Coral Reef Ecosystems: A Review

Directory of Open Access Journals (Sweden)

L. Charpy

2012-01-01

Full Text Available Cyanobacteria have dominated marine environments and have been reef builders on Earth for more than three million years (myr. Cyanobacteria still play an essential role in modern coral reef ecosystems by forming a major component of epiphytic, epilithic, and endolithic communities as well as of microbial mats. Cyanobacteria are grazed by reef organisms and also provide nitrogen to the coral reef ecosystems through nitrogen fixation. Recently, new unicellular cyanobacteria that express nitrogenase were found in the open ocean and in coral reef lagoons. Furthermore, cyanobacteria are important in calcification and decalcification. All limestone surfaces have a layer of boring algae in which cyanobacteria often play a dominant role. Cyanobacterial symbioses are abundant in coral reefs; the most common hosts are sponges and ascidians. Cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. Cyanobacteria can also form pathogenic microbial consortia in association with other microbes on living coral tissues, causing coral tissue lysis and death, and considerable declines in coral reefs. In deep lagoons, coccoid cyanobacteria are abundant and are grazed by ciliates, heteroflagellates, and the benthic coral reef community. Cyanobacteria produce metabolites that act as attractants for some species and deterrents for some grazers of the reef communities.

Wnt signaling balances specification of the cardiac and pharyngeal muscle fields

Science.gov (United States)

Mandal, Amrita; Holowiecki, Andrew; Song, Yuntao Charlie; Waxman, Joshua S.

2017-01-01

Canonical Wnt/β-catenin (Wnt) signaling plays multiple conserved roles during fate specification of cardiac progenitors in developing vertebrate embryos. Although lineage analysis in ascidians and mice has indicated there is a close relationship between the cardiac second heart field (SHF) and pharyngeal muscle (PM) progenitors, the signals underlying directional fate decisions of the cells within the cardio-pharyngeal muscle field in vertebrates are not yet understood. Here, we examined the temporal requirements of Wnt signaling in cardiac and PM development. In contrast to a previous report in chicken embryos that suggested Wnt inhibits PM development during somitogenesis, we find that in zebrafish embryos Wnt signaling is sufficient to repress PM development during anterior-posterior patterning. Importantly, the temporal sensitivity of dorso-anterior PMs to increased Wnt signaling largely overlaps with when Wnt signaling promotes specification of the adjacent cardiac progenitors. Furthermore, we find that excess early Wnt signaling can cell autonomously promote expansion of the first heart field (FHF) progenitors at the expense of PM and SHF within the anterior lateral plate mesoderm (ALPM). Our study provides insight into an antagonistic developmental mechanism that balances the sizes of the adjacent cardiac and PM progenitor fields in early vertebrate embryos. PMID:28087459

An empirical examination of consumer effects across twenty degrees of latitude.

Science.gov (United States)

Lavender, James T; Dafforn, Katherine A; Bishop, Melanie J; Johnston, Emma L

2017-09-01

The strength and importance of consumer effects are predicted to increase toward low latitudes, but this hypothesis has rarely been tested using a spatially consistent methodology. In a consumer-exclusion experiment spanning twenty degrees of latitude along the east Australian coast, the magnitude of consumer effects on sub-tidal sessile assemblage composition was not greater at low than high latitudes. Across caged and control assemblages, Shannon's diversity, Pielou's evenness, and richness of functional groups decreased with increasing latitude, but the magnitude of consumer effects on these metrics did not display consistent latitudinal gradients. Instead, latitudinal gradients in consumer effects were apparent for individual functional groups. Solitary ascidians displayed the pattern consistent with predictions of greater direct effects of predators at low than high latitude. As consumers reduced the biomass of this and other competitive dominants, groups less prone to predation (e.g., hydroids, various groups of bryozoans) were able to take advantage of freed space in the presence of consumers and show increased abundances there. This large-scale empirical study demonstrates the complexity of species interactions, and the failure of assemblage-level metrics to adequately capture consumer effects over large spatial gradients. © 2017 by the Ecological Society of America.

Delta13C and delta15N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica.

Science.gov (United States)

Conlan, Kathleen E; Rau, Greg H; Kvitek, Rikk G

2006-12-01

In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic.

The genetic covariance between life cycle stages separated by metamorphosis.

Science.gov (United States)

Aguirre, J David; Blows, Mark W; Marshall, Dustin J

2014-08-07

Metamorphosis is common in animals, yet the genetic associations between life cycle stages are poorly understood. Given the radical changes that occur at metamorphosis, selection may differ before and after metamorphosis, and the extent that genetic associations between pre- and post-metamorphic traits constrain evolutionary change is a subject of considerable interest. In some instances, metamorphosis may allow the genetic decoupling of life cycle stages, whereas in others, metamorphosis could allow complementary responses to selection across the life cycle. Using a diallel breeding design, we measured viability at four ontogenetic stages (embryo, larval, juvenile and adult viability), in the ascidian Ciona intestinalis and examined the orientation of additive genetic variation with respect to the metamorphic boundary. We found support for one eigenvector of G: (gobsmax ), which contrasted larval viability against embryo viability and juvenile viability. Target matrix rotation confirmed that while gobsmax shows genetic associations can extend beyond metamorphosis, there is still considerable scope for decoupled phenotypic evolution. Therefore, although genetic associations across metamorphosis could limit that range of phenotypes that are attainable, traits on either side of the metamorphic boundary are capable of some independent evolutionary change in response to the divergent conditions encountered during each life cycle stage. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Marine-Derived 2-Aminoimidazolone Alkaloids. Leucettamine B-Related Polyandrocarpamines Inhibit Mammalian and Protozoan DYRK & CLK Kinases

Directory of Open Access Journals (Sweden)

Nadège Loaëc

2017-10-01

Full Text Available A large diversity of 2-aminoimidazolone alkaloids is produced by various marine invertebrates, especially by the marine Calcareous sponges Leucetta and Clathrina. The phylogeny of these sponges and the wide scope of 2-aminoimidazolone alkaloids they produce are reviewed in this article. The origin (invertebrate cells, associated microorganisms, or filtered plankton, physiological functions, and natural molecular targets of these alkaloids are largely unknown. Following the identification of leucettamine B as an inhibitor of selected protein kinases, we synthesized a family of analogues, collectively named leucettines, as potent inhibitors of DYRKs (dual-specificity, tyrosine phosphorylation regulated kinases and CLKs (cdc2-like kinases and potential pharmacological leads for the treatment of several diseases, including Alzheimer’s disease and Down syndrome. We assembled a small library of marine sponge- and ascidian-derived 2-aminoimidazolone alkaloids, along with several synthetic analogues, and tested them on a panel of mammalian and protozoan kinases. Polyandrocarpamines A and B were found to be potent and selective inhibitors of DYRKs and CLKs. They inhibited cyclin D1 phosphorylation on a DYRK1A phosphosite in cultured cells. 2-Aminoimidazolones thus represent a promising chemical scaffold for the design of potential therapeutic drug candidates acting as specific inhibitors of disease-relevant kinases, and possibly other disease-relevant targets.

The ascidian Styela plicata hemocytes as a potential biomarker of marine pollution: In vitro effects of seawater and organic mercury.

Science.gov (United States)

Parrinello, D; Bellante, A; Parisi, M G; Sanfratello, M A; Indelicato, S; Piazzese, D; Cammarata, M

2017-02-01

Toxic metals, such as mercury, contribute substantially to anthropogenic pollution in many estuarine environments. Animals living in those environments, particularly invertebrate filter feeders like tunicates, can be used as bioindicators. In an attempt to identify cellular markers for revealing pollution, this study examined in vitro the effects of different concentrations of methyl mercury on Styela plicata hemocytes. The harvested hemocytes from S. plicata that were exposed to the metal had a significant mortality, cellular count and morphometric alterations. These findings provided evidence of MeHg immunotoxic effects on S. plicata, resulting in hemocyte death and morphological changes induced by cytoskeleton alterations. Thus, a morphometric cellular parameter, such as spreading ability, was used as a complementary method for differentiation between hemocytes treated with a marine solution (as a negative control) and hemocytes incubated with methylmercury and/or Sicilian seawater samples. Copyright © 2016 Elsevier Inc. All rights reserved.

Vertebrate Embryonic Cleavage Pattern Determination.

Science.gov (United States)

Hasley, Andrew; Chavez, Shawn; Danilchik, Michael; Wühr, Martin; Pelegri, Francisco

2017-01-01

The pattern of the earliest cell divisions in a vertebrate embryo lays the groundwork for later developmental events such as gastrulation, organogenesis, and overall body plan establishment. Understanding these early cleavage patterns and the mechanisms that create them is thus crucial for the study of vertebrate development. This chapter describes the early cleavage stages for species representing ray-finned fish, amphibians, birds, reptiles, mammals, and proto-vertebrate ascidians and summarizes current understanding of the mechanisms that govern these patterns. The nearly universal influence of cell shape on orientation and positioning of spindles and cleavage furrows and the mechanisms that mediate this influence are discussed. We discuss in particular models of aster and spindle centering and orientation in large embryonic blastomeres that rely on asymmetric internal pulling forces generated by the cleavage furrow for the previous cell cycle. Also explored are mechanisms that integrate cell division given the limited supply of cellular building blocks in the egg and several-fold changes of cell size during early development, as well as cytoskeletal specializations specific to early blastomeres including processes leading to blastomere cohesion. Finally, we discuss evolutionary conclusions beginning to emerge from the contemporary analysis of the phylogenetic distributions of cleavage patterns. In sum, this chapter seeks to summarize our current understanding of vertebrate early embryonic cleavage patterns and their control and evolution.

Biophysical characterization of the fluorescent protein voltage probe VSFP2.3 based on the voltage-sensing domain of Ci-VSP.

Science.gov (United States)

Lundby, Alicia; Akemann, Walther; Knöpfel, Thomas

2010-11-01

A voltage sensitive phosphatase was discovered in the ascidian Ciona intestinalis. The phosphatase, Ci-VSP, contains a voltage-sensing domain homologous to those known from voltage-gated ion channels, but unlike ion channels, the voltage-sensing domain of Ci-VSP can reside in the cell membrane as a monomer. We fused the voltage-sensing domain of Ci-VSP to a pair of fluorescent reporter proteins to generate a genetically encodable voltage-sensing fluorescent probe, VSFP2.3. VSFP2.3 is a fluorescent voltage probe that reports changes in membrane potential as a FRET (fluorescence resonance energy transfer) signal. Here we report sensing current measurements from VSFP2.3, and show that VSFP2.3 carries 1.2 e sensing charges, which are displaced within 1.5 ms. The sensing currents become faster at higher temperatures, and the voltage dependence of the decay time constants is temperature dependent. Neutralization of an arginine in S4, previously suggested to be a sensing charge, and measuring associated sensing currents indicate that this charge is likely to reside at the membrane-aqueous interface rather than within the membrane electric field. The data presented give us insights into the voltage-sensing mechanism of Ci-VSP, which will allow us to further improve the sensitivity and kinetics of the family of VSFP proteins.

{delta}{sup 13}C and {delta}{sup 15}N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica

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Conlan, Kathleen E. [Canadian Musem of Nature, P.O. Box 3443 Station D, Ottawa, Ont., K1P 6P4 (Canada)]. E-mail kconlan@mus-nature.ca; Rau, Greg H. [Institute of Marine Sciences, University of California, Santa Cruz, CA 95064 (United States); Kvitek, Rikk G. [Earth Systems Science and Policy, California State University Monterey Bay, 100 Campus Center, Seaside, CA 93955 (United States)

2006-12-15

In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic.

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

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Louis P. Sandjo

2015-09-01

Full Text Available This review focuses on pyridoacridine-related metabolites as one biologically interesting group of alkaloids identified from marine sources. They are produced by marine sponges, ascidians and tunicates, and they are structurally comprised of four to eight fused rings including heterocycles. Acridine, acridone, dihydroacridine, and quinolone cores are features regularly found in these alkaloid skeletons. The lack of hydrogen atoms next to quaternary carbon atoms for two or three rings makes the chemical shift assignment a difficult task. In this regard, one of the aims of this review is the compilation of previously reported, pyridoacridine 13C NMR data. Observations have been made on the delocalization of electrons and the presence of some functional groups that lead to changes in the chemical shift of some carbon resonances. The lack of mass spectra information for these alkaloids due to the compactness of their structures is further discussed. Moreover, the biosynthetic pathways of some of these metabolites have been shown since they could inspire biomimetic synthesis. The synthesis routes used to prepare members of these marine alkaloids (as well as their analogues, which are synthesized for biological purposes are also discussed. Pyridoacridines were found to have a large spectrum of bioactivity and this review highlights and compares the pharmacophores that are responsible for the observed bioactivity.

Tbx2/3 is an essential mediator within the Brachyury gene network during Ciona notochord development.

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José-Edwards, Diana S; Oda-Ishii, Izumi; Nibu, Yutaka; Di Gregorio, Anna

2013-06-01

T-box genes are potent regulators of mesoderm development in many metazoans. In chordate embryos, the T-box transcription factor Brachyury (Bra) is required for specification and differentiation of the notochord. In some chordates, including the ascidian Ciona, members of the Tbx2 subfamily of T-box genes are also expressed in this tissue; however, their regulatory relationships with Bra and their contributions to the development of the notochord remain uncharacterized. We determined that the notochord expression of Ciona Tbx2/3 (Ci-Tbx2/3) requires Ci-Bra, and identified a Ci-Tbx2/3 notochord CRM that necessitates multiple Ci-Bra binding sites for its activity. Expression of mutant forms of Ci-Tbx2/3 in the developing notochord revealed a role for this transcription factor primarily in convergent extension. Through microarray screens, we uncovered numerous Ci-Tbx2/3 targets, some of which overlap with known Ci-Bra-downstream notochord genes. Among the Ci-Tbx2/3 notochord targets are evolutionarily conserved genes, including caspases, lineage-specific genes, such as Noto4, and newly identified genes, such as MLKL. This work sheds light on a large section of the notochord regulatory circuitry controlled by T-box factors, and reveals new components of the complement of genes required for the proper formation of this structure.

Anterior-posterior regionalized gene expression in the Ciona notochord.

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Reeves, Wendy; Thayer, Rachel; Veeman, Michael

2014-04-01

In the simple ascidian chordate Ciona, the signaling pathways and gene regulatory networks giving rise to initial notochord induction are largely understood and the mechanisms of notochord morphogenesis are being systematically elucidated. The notochord has generally been thought of as a non-compartmentalized or regionalized organ that is not finely patterned at the level of gene expression. Quantitative imaging methods have recently shown, however, that notochord cell size, shape, and behavior vary consistently along the anterior-posterior (AP) axis. Here we screen candidate genes by whole mount in situ hybridization for potential AP asymmetry. We identify 4 genes that show non-uniform expression in the notochord. Ezrin/radixin/moesin (ERM) is expressed more strongly in the secondary notochord lineage than the primary. CTGF is expressed stochastically in a subset of notochord cells. A novel calmodulin-like gene (BCamL) is expressed more strongly at both the anterior and posterior tips of the notochord. A TGF-β ortholog is expressed in a gradient from posterior to anterior. The asymmetries in ERM, BCamL, and TGF-β expression are evident even before the notochord cells have intercalated into a single-file column. We conclude that the Ciona notochord is not a homogeneous tissue but instead shows distinct patterns of regionalized gene expression. Copyright © 2013 Wiley Periodicals, Inc.

Environmental and ecological changes associated with a marina.

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Rivero, Natalie K; Dafforn, Katherine A; Coleman, Melinda A; Johnston, Emma L

2013-01-01

Anthropogenic modifications to waterways are common and their ecological consequences must be understood to effectively conserve local biodiversity. The facilitation of recreational boating activities often requires substantial alteration of natural areas, however the environmental and ecological consequences of such alterations are rarely described in the scientific literature. In this study, ecological and physico-chemical conditions were investigated in a recreational boating marina, located inside a marine park on the south-east coast of Australia. Recruitment panels were deployed for 8 weeks both inside and outside the marina, and differences in the composition of the developing fouling communities were observed. The recruitment of taxa, which often have short-lived larvae, was increased inside the marina (bryozoans, spirorbids and sponges) while the recruitment of taxa, which often have longer-lived larvae, was reduced or absent (barnacles, solitary ascidians and non-spirorbid polychaetes). Differences were also observed in environmental conditions inside the marina cf. directly outside. The marina environment had higher turbidity, temperature and pH along with higher concentrations of lead and copper in suspended sediments, while flow rates and trapped sediment loads were reduced inside the marina. The differences observed in the study suggest that there may be marked environmental changes associated with marina developments. The potential ecological consequences of these changes should be a primary consideration during the planning process, particularly for developments in locations of notable ecological value.

A rapid assessment survey of invasive species of macrobenthic invertebrates in Korean waters

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Park, Chul; Kim, Sung-Tae; Hong, Jae-Sang; Choi, Keun-Hyung

2017-09-01

Introduced species are a growing and imminent threat to living marine resources in parts of the world's oceans. The present study is a rapid assessment survey of invasive macrobenthic invertebrate species in Korean ports. We surveyed over 40 ports around Korea during the period of May 2010 March 2013. Among the sampling sites were concrete walls, docks and associated floats, bumpers, tires, and ropes which might harbor non-native species. We found 15 invasive species as follows: one Sponge, two Bryozoans, three Mollusks, one Polychaete, four Cirripedes, and four Ascidians. Three morphologically similar species, namely X. atrata, M. galloprovincialis, and X. securis were further examined for distinctions in their morphology. Although they could be reasonably distinguished based on shell shapes, significant overlap was noted so that additional analysis may be required to correctly distinguish them. Although many of the introduced species have already spread to all three coastal areas, newly arrived invasive species showed a relatively restricted range, with a serpulid polychaete Ficopomatus enigmaticus and a mytilid bivalve Xenostrobus securis found only at a few sites on the East Coast. An exception is for Balanus perforatus, which has rapidly colonized the East coast of Korea following its introduction into the region. Successful management of invasive macrobenthic invertebrates should be established in order to contain the spread of these newly arrived species.

Voltage sensitive phosphatases: emerging kinship to protein tyrosine phosphatases from structure-function research

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Kirstin eHobiger

2015-02-01

Full Text Available The transmembrane protein Ci-VSP from the ascidian Ciona intestinalis was described as first member of a fascinating family of enzymes, the voltage sensitive phosphatases (VSPs. Ci-VSP and its voltage-activated homologs from other species are stimulated by positive membrane potentials and dephosphorylate the head groups of negatively charged phosphoinositide phosphates (PIPs. In doing so, VSPs act as control centers at the cytosolic membrane surface, because they intervene in signaling cascades that are mediated by PIP lipids. The characteristic motif CX5RT/S in the active site classifies VSPs as members of the huge family of cysteine-based protein tyrosine phosphatases (PTPs. Although PTPs have already been well characterized regarding both, structure and function, their relationship to VSPs has drawn only limited attention so far. Therefore, the intention of this review is to give a short overview about the extensive knowledge about PTPs in relation to the facts known about VSPs. Here, we concentrate on the structural features of the catalytic domain which are similar between both classes of phosphatases and their consequences for the enzymatic function. By discussing results obtained from crystal structures, molecular dynamics simulations, and mutagenesis studies, a possible mechanism for the catalytic cycle of VSPs is presented based on that one proposed for PTPs. In this way, we want to link the knowledge about the catalytic activity of VSPs and PTPs.

Calcium sensors of ciliary outer arm dynein: functions and phylogenetic considerations for eukaryotic evolution.

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Inaba, Kazuo

2015-01-01

The motility of eukaryotic cilia and flagella is modulated in response to several extracellular stimuli. Ca(2+) is the most critical intracellular factor for these changes in motility, directly acting on the axonemes and altering flagellar asymmetry. Calaxin is an opisthokont-specific neuronal calcium sensor protein first described in the sperm of the ascidian Ciona intestinalis. It binds to a heavy chain of two-headed outer arm dynein in a Ca(2+)-dependent manner and regulates 'asymmetric' wave propagation at high concentrations of Ca(2+). A Ca(2+)-binding subunit of outer arm dynein in Chlamydomonas reinhardtii, the light chain 4 (LC4), which is a Ca(2+)-sensor phylogenetically different from calaxin, shows Ca(2+)-dependent binding to a heavy chain of three-headed outer arm dynein. However, LC4 appears to participate in 'symmetric' wave propagation at high concentrations of Ca(2+). LC4-type dynein light chain is present in bikonts, except for some subclasses of the Excavata. Thus, flagellar asymmetry-symmetry conversion in response to Ca(2+) concentration represents a 'mirror image' relationship between Ciona and Chlamydomonas. Phylogenetic analyses indicate the duplication, divergence, and loss of heavy chain and Ca(2+)-sensors of outer arm dynein among excavate species. These features imply a divergence point with respect to Ca(2+)-dependent regulation of outer arm dynein in cilia and flagella during the evolution of eukaryotic supergroups.

Marine actinobacteria associated with marine organisms and their potentials in producing pharmaceutical natural products.

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Valliappan, Karuppiah; Sun, Wei; Li, Zhiyong

2014-09-01

Actinobacteria are ubiquitous in the marine environment, playing an important ecological role in the recycling of refractory biomaterials and producing novel natural products with pharmic applications. Actinobacteria have been detected or isolated from the marine creatures such as sponges, corals, mollusks, ascidians, seaweeds, and seagrass. Marine organism-associated actinobacterial 16S rRNA gene sequences, i.e., 3,003 sequences, deposited in the NCBI database clearly revealed enormous numbers of actinobacteria associated with marine organisms. For example, RDP classification of these sequences showed that 112 and 62 actinobacterial genera were associated with the sponges and corals, respectively. In most cases, it is expected that these actinobacteria protect the host against pathogens by producing bioactive compounds. Natural products investigation and functional gene screening of the actinobacteria associated with the marine organisms revealed that they can synthesize numerous natural products including polyketides, isoprenoids, phenazines, peptides, indolocarbazoles, sterols, and others. These compounds showed anticancer, antimicrobial, antiparasitic, neurological, antioxidant, and anti-HIV activities. Therefore, marine organism-associated actinobacteria represent an important resource for marine drugs. It is an upcoming field of research to search for novel actinobacteria and pharmaceutical natural products from actinobacteria associated with the marine organisms. In this review, we attempt to summarize the present knowledge on the diversity and natural products production of actinobacteria associated with the marine organisms, based on the publications from 1991 to 2013.

Evolutionary changes in the notochord genetic toolkit: a comparative analysis of notochord genes in the ascidian Ciona and the larvacean Oikopleura.

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Kugler, Jamie E; Kerner, Pierre; Bouquet, Jean-Marie; Jiang, Di; Di Gregorio, Anna

2011-01-20

The notochord is a defining feature of the chordate clade, and invertebrate chordates, such as tunicates, are uniquely suited for studies of this structure. Here we used a well-characterized set of 50 notochord genes known to be targets of the notochord-specific Brachyury transcription factor in one tunicate, Ciona intestinalis (Class Ascidiacea), to begin determining whether the same genetic toolkit is employed to build the notochord in another tunicate, Oikopleura dioica (Class Larvacea). We identified Oikopleura orthologs of the Ciona notochord genes, as well as lineage-specific duplicates for which we determined the phylogenetic relationships with related genes from other chordates, and we analyzed their expression patterns in Oikopleura embryos. Of the 50 Ciona notochord genes that were used as a reference, only 26 had clearly identifiable orthologs in Oikopleura. Two of these conserved genes appeared to have undergone Oikopleura- and/or tunicate-specific duplications, and one was present in three copies in Oikopleura, thus bringing the number of genes to test to 30. We were able to clone and test 28 of these genes. Thirteen of the 28 Oikopleura orthologs of Ciona notochord genes showed clear expression in all or in part of the Oikopleura notochord, seven were diffusely expressed throughout the tail, six were expressed in tissues other than the notochord, while two probes did not provide a detectable signal at any of the stages analyzed. One of the notochord genes identified, Oikopleura netrin, was found to be unevenly expressed in notochord cells, in a pattern reminiscent of that previously observed for one of the Oikopleura Hox genes. A surprisingly high number of Ciona notochord genes do not have apparent counterparts in Oikopleura, and only a fraction of the evolutionarily conserved genes show clear notochord expression. This suggests that Ciona and Oikopleura, despite the morphological similarities of their notochords, have developed rather divergent sets of notochord genes after their split from a common tunicate ancestor. This study demonstrates that comparisons between divergent tunicates can lead to insights into the basic complement of genes sufficient for notochord development, and elucidate the constraints that control its composition.

Evolutionary changes in the notochord genetic toolkit: a comparative analysis of notochord genes in the ascidian Ciona and the larvacean Oikopleura

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Jiang Di

2011-01-01

Full Text Available Abstract Background The notochord is a defining feature of the chordate clade, and invertebrate chordates, such as tunicates, are uniquely suited for studies of this structure. Here we used a well-characterized set of 50 notochord genes known to be targets of the notochord-specific Brachyury transcription factor in one tunicate, Ciona intestinalis (Class Ascidiacea, to begin determining whether the same genetic toolkit is employed to build the notochord in another tunicate, Oikopleura dioica (Class Larvacea. We identified Oikopleura orthologs of the Ciona notochord genes, as well as lineage-specific duplicates for which we determined the phylogenetic relationships with related genes from other chordates, and we analyzed their expression patterns in Oikopleura embryos. Results Of the 50 Ciona notochord genes that were used as a reference, only 26 had clearly identifiable orthologs in Oikopleura. Two of these conserved genes appeared to have undergone Oikopleura- and/or tunicate-specific duplications, and one was present in three copies in Oikopleura, thus bringing the number of genes to test to 30. We were able to clone and test 28 of these genes. Thirteen of the 28 Oikopleura orthologs of Ciona notochord genes showed clear expression in all or in part of the Oikopleura notochord, seven were diffusely expressed throughout the tail, six were expressed in tissues other than the notochord, while two probes did not provide a detectable signal at any of the stages analyzed. One of the notochord genes identified, Oikopleura netrin, was found to be unevenly expressed in notochord cells, in a pattern reminiscent of that previously observed for one of the Oikopleura Hox genes. Conclusions A surprisingly high number of Ciona notochord genes do not have apparent counterparts in Oikopleura, and only a fraction of the evolutionarily conserved genes show clear notochord expression. This suggests that Ciona and Oikopleura, despite the morphological similarities of their notochords, have developed rather divergent sets of notochord genes after their split from a common tunicate ancestor. This study demonstrates that comparisons between divergent tunicates can lead to insights into the basic complement of genes sufficient for notochord development, and elucidate the constraints that control its composition.

LPS injection reprograms the expression and the 3' UTR of a CAP gene by alternative polyadenylation and the formation of a GAIT element in Ciona intestinalis.

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Vizzini, Aiti; Bonura, Angela; Longo, Valeria; Sanfratello, Maria Antonietta; Parrinello, Daniela; Cammarata, Matteo; Colombo, Paolo

2016-09-01

The diversification of cellular functions is one of the major characteristics of multicellular organisms which allow cells to modulate their gene expression, leading to the formation of transcripts and proteins with different functions and concentrations in response to different stimuli. CAP genes represent a widespread family of proteins belonging to the cysteine-rich secretory protein, antigen 5 and pathogenesis-related 1 superfamily which, it has been proposed, play key roles in the infection process and the modulation of immune responses in host animals. The ascidian Ciona intestinalis represents a group of proto-chordates with an exclusively innate immune system that has been widely studied in the field of comparative and developmental immunology. Using this biological system, we describe the identification of a novel APA mechanism by which an intronic polyadenylation signal is activated by LPS injection, leading to the formation of a shorter CAP mRNA capable of expressing the first CAP exon plus 19 amino acid residues whose sequence is contained within the first intron of the annotated gene. Furthermore, such an APA event causes the expression of a translational controlling cis-acting GAIT element which is not present in the previously isolated CAP isoform and identified in the 3'-UTR of other immune-related genes, suggesting an intriguing scenario in which both transcriptional and post-transcriptional control mechanisms are involved in the activation of the CAP gene during inflammatory response in C. intestinalis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Defensive Metabolites from Antarctic Invertebrates: Does Energetic Content Interfere with Feeding Repellence?

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Laura Núñez-Pons

2014-06-01

Full Text Available Many bioactive products from benthic invertebrates mediating ecological interactions have proved to reduce predation, but their mechanisms of action, and their molecular identities, are usually unknown. It was suggested, yet scarcely investigated, that nutritional quality interferes with defensive metabolites. This means that antifeedants would be less effective when combined with energetically rich prey, and that higher amounts of defensive compounds would be needed for predator avoidance. We evaluated the effects of five types of repellents obtained from Antarctic invertebrates, in combination with diets of different energetic values. The compounds came from soft corals, ascidians and hexactinellid sponges; they included wax esters, alkaloids, a meroterpenoid, a steroid, and the recently described organic acid, glassponsine. Feeding repellency was tested through preference assays by preparing diets (alginate pearls combining different energetic content and inorganic material. Experimental diets contained various concentrations of each repellent product, and were offered along with control compound-free pearls, to the Antarctic omnivore amphipod Cheirimedon femoratus. Meridianin alkaloids were the most active repellents, and wax esters were the least active when combined with foods of distinct energetic content. Our data show that levels of repellency vary for each compound, and that they perform differently when mixed with distinct assay foods. The natural products that interacted the most with energetic content were those occurring in nature at higher concentrations. The bioactivity of the remaining metabolites tested was found to depend on a threshold concentration, enough to elicit feeding repellence, independently from nutritional quality.

Toll-like receptors of deuterostome invertebrates

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Honoo eSatake

2012-02-01

Full Text Available Defensive systems against pathogens are responsible not only for survival or lifetime of an individual but also for the evolution of a species. Innate immunity is expected to be more important for invertebrates than mammals, given that adaptive immunity has not been acquired in the former. Toll-like receptors (TLRs have been shown to play a crucial role in host defense of pathogenic microbes in innate immunity of mammals. Recent genome-wide analyses have suggested that TLR or their related genes are conserved in invertebrates. In particular, numerous TLR-related gene candidates were detected in deuterostome invertebrates including a sea urchin (222 TLR-related gene candidates and amphioxus (72 TLR-related gene candidates. Molecular phylogenetic analysis verified that most of sea urchin or amphioxus TLR candidates are paralogous, suggesting that these organisms expanded TLR-related genes in a species-specific manner. In contrast, another deuterostome invertebrate, an ascidian, Ciona intestinalis, was found to possess only two TLR genes. Moreover, Ciona TLRs, Ci-TLR1 and -2, were shown to possess hybrid functionality of mammalian TLRs. Such functionality of Ci-TLRs could not be predicted by sequence comparison with vertebrate TLRs, indicating the confounding evolutionary lineages of deuterostome invertebrate TLRs or their candidates. In this review article, we present recent advances in studies of TLRs or their candidates of deuterostome invertebrates, and provide insight into an evolutionary process of TLRs.

Eph regulates dorsoventral asymmetry of the notochord plate and convergent extension-mediated notochord formation.

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Oda-Ishii, Izumi; Ishii, Yasuo; Mikawa, Takashi

2010-10-29

The notochord is a signaling center required for the patterning of the vertebrate embryonic midline, however, the molecular and cellular mechanisms involved in the formation of this essential embryonic tissue remain unclear. The urochordate Ciona intestinalis develops a simple notochord from 40 specific postmitotic mesodermal cells. The precursors intercalate mediolaterally and establish a single array of disk-shaped notochord cells along the midline. However, the role that notochord precursor polarization, particularly along the dorsoventral axis, plays in this morphogenetic process remains poorly understood. Here we show that the notochord preferentially accumulates an apical cell polarity marker, aPKC, ventrally and a basement membrane marker, laminin, dorsally. This asymmetric accumulation of apicobasal cell polarity markers along the embryonic dorsoventral axis was sustained in notochord precursors during convergence and extension. Further, of several members of the Eph gene family implicated in cellular and tissue morphogenesis, only Ci-Eph4 was predominantly expressed in the notochord throughout cell intercalation. Introduction of a dominant-negative Ci-Eph4 to notochord precursors diminished asymmetric accumulation of apicobasal cell polarity markers, leading to defective intercalation. In contrast, misexpression of a dominant-negative mutant of a planar cell polarity gene Dishevelled preserved asymmetric accumulation of aPKC and laminin in notochord precursors, although their intercalation was incomplete. Our data support a model in which in ascidian embryos Eph-dependent dorsoventral polarity of notochord precursors plays a crucial role in mediolateral cell intercalation and is required for proper notochord morphogenesis.

The evolutionarily conserved leprecan gene: its regulation by Brachyury and its role in the developing Ciona notochord.

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Dunn, Matthew P; Di Gregorio, Anna

2009-04-15

In Ciona intestinalis, leprecan was identified as a target of the notochord-specific transcription factor Ciona Brachyury (Ci-Bra) (Takahashi, H., Hotta, K., Erives, A., Di Gregorio, A., Zeller, R.W., Levine, M., Satoh, N., 1999. Brachyury downstream notochord differentiation in the ascidian embryo. Genes Dev. 13, 1519-1523). By screening approximately 14 kb of the Ci-leprecan locus for cis-regulatory activity, we have identified a 581-bp minimal notochord-specific cis-regulatory module (CRM) whose activity depends upon T-box binding sites located at the 3'-end of its sequence. These sites are specifically bound in vitro by a GST-Ci-Bra fusion protein, and mutations that abolish binding in vitro result in loss or decrease of regulatory activity in vivo. Serial deletions of the 581-bp notochord CRM revealed that this sequence is also able to direct expression in muscle cells through the same T-box sites that are utilized by Ci-Bra in the notochord, which are also bound in vitro by the muscle-specific T-box activators Ci-Tbx6b and Ci-Tbx6c. Additionally, we created plasmids aimed to interfere with the function of Ci-leprecan and categorized the resulting phenotypes, which consist of variable dislocations of notochord cells along the anterior-posterior axis. Together, these observations provide mechanistic insights generally applicable to T-box transcription factors and their target sequences, as well as a first set of clues on the function of Leprecan in early chordate development.

Sperm viability assessment in marine invertebrates by fluorescent staining and spectrofluorimetry: A promising tool for assessing marine pollution impact.

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Gallo, Alessandra; Boni, Raffaele; Tosti, Elisabetta

2018-01-01

The viability of spermatozoa is a crucial parameter to evaluate their quality that is an important issue in ecotoxicological studies. Here, a new method has been developed to rapidly determine the viability of spermatozoa in three marine invertebrates: the ascidian Ciona intestinalis, the sea urchin Paracentrotus lividus and the mollusc Mytilus galloprovincialis. This method employed the dual DNA fluorescent staining coupled with spectrofluorimetric analysis. The dual fluorescent staining used the SYBR-14 stained live spermatozoa and propidium iodide stained degenerated cells that had lost membrane integrity. Stain uptake was assessed by confocal microscopy and then the percentage of live and dead spermatozoa was quantified by spectrofluorimetric analysis. The microscopic examination revealed three populations of spermatozoa: living-SYBR-14 stained, dead-PI stained, and dying-doubly stained spermatozoa. The fluorescence emission peak values recorded in a spectrofluorimeter provide the portion of live and dead spermatozoa showing a significant negative correlation. The stain combination was further validated using known ratios of live and dead spermatozoa. The present study demonstrated that the dual DNA staining with SYBR-14 and propidium iodide was effective in assessing viability of spermatozoa in marine invertebrates and that spectrofluorimetric analysis can be successfully employed to evaluate the percentage of live and dead spermatozoa. The method develop herein is simple, accurate, rapid, sensitive, and cost-effective, so it could be a useful tool by which marine pollutants may be screened for spermiotoxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

Defensive Metabolites from Antarctic Invertebrates: Does Energetic Content Interfere with Feeding Repellence?

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Núñez-Pons, Laura; Avila, Conxita

2014-01-01

Many bioactive products from benthic invertebrates mediating ecological interactions have proved to reduce predation, but their mechanisms of action, and their molecular identities, are usually unknown. It was suggested, yet scarcely investigated, that nutritional quality interferes with defensive metabolites. This means that antifeedants would be less effective when combined with energetically rich prey, and that higher amounts of defensive compounds would be needed for predator avoidance. We evaluated the effects of five types of repellents obtained from Antarctic invertebrates, in combination with diets of different energetic values. The compounds came from soft corals, ascidians and hexactinellid sponges; they included wax esters, alkaloids, a meroterpenoid, a steroid, and the recently described organic acid, glassponsine. Feeding repellency was tested through preference assays by preparing diets (alginate pearls) combining different energetic content and inorganic material. Experimental diets contained various concentrations of each repellent product, and were offered along with control compound-free pearls, to the Antarctic omnivore amphipod Cheirimedon femoratus. Meridianin alkaloids were the most active repellents, and wax esters were the least active when combined with foods of distinct energetic content. Our data show that levels of repellency vary for each compound, and that they perform differently when mixed with distinct assay foods. The natural products that interacted the most with energetic content were those occurring in nature at higher concentrations. The bioactivity of the remaining metabolites tested was found to depend on a threshold concentration, enough to elicit feeding repellence, independently from nutritional quality. PMID:24962273

The Suez Canal as a habitat and pathway for marine algae and seagrasses

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Aleem, A. A.

The Suez Canal supports a diversified benthic algal flora; 133 species of benthic algae are now known from the Canal, as compared with only 24 in 1924. The vertical and horizontal distribution of algae is considered in relation to hydrographic factors. The algae display zonation and 3-4 algal belts are distinguished on the Canal banks on buoys and pier supports. Associated fauna include Balanus amphitrite and Brachidontes variabilis, together with various hydroids, sponges, ascidians, asteroids, ophiuroids and crustaceans. Merceriella enigmatica thrives well in brackish water habitats. The algal flora in the Bitter Lakes resembles that in the Red Sea. The number of Red Sea species decreases from Suez to Port Said in the littoral zone. On the other hand, bottom algae predominantly belong to Red Sea flora. Thirty of the species of algae found belong to the Indo-Pacific flora; half of these are new records to the Canal. Several of these Indo-Pacific algae have recently become established in the Eastern Mediterranean, whereas only two of the Mediterranean macro-algal flora (viz. Caulerpa prolifera and Halopteris scoparia) have been found in the Gulf of Suez. Two seagrasses, Halopia ovalis and Thalassia hemprichii, are recorded for the first time in the Canal. Only Halophila stipulacea has found its way into the Mediterranean via the Suez Canal, but none of the Mediterranean seagrasses is found either in the Canal or in the Red Sea.

Marine Natural Products Acting on the Acetylcholine-Binding Protein and Nicotinic Receptors: From Computer Modeling to Binding Studies and Electrophysiology

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Denis Kudryavtsev

2014-03-01

Full Text Available For a small library of natural products from marine sponges and ascidians, in silico docking to the Lymnaea stagnalis acetylcholine-binding protein (AChBP, a model for the ligand-binding domains of nicotinic acetylcholine receptors (nAChRs, was carried out and the possibility of complex formation was revealed. It was further experimentally confirmed via competition with radioiodinated α-bungarotoxin ([125I]-αBgt for binding to AChBP of the majority of analyzed compounds. Alkaloids pibocin, varacin and makaluvamines С and G had relatively high affinities (Ki 0.5–1.3 μM. With the muscle-type nAChR from Torpedo californica ray and human neuronal α7 nAChR, heterologously expressed in the GH4C1 cell line, no competition with [125I]-αBgt was detected in four compounds, while the rest showed an inhibition. Makaluvamines (Ki ~ 1.5 μM were the most active compounds, but only makaluvamine G and crambescidine 359 revealed a weak selectivity towards muscle-type nAChR. Rhizochalin, aglycone of rhizochalin, pibocin, makaluvamine G, monanchocidin, crambescidine 359 and aaptamine showed inhibitory activities in electrophysiology experiments on the mouse muscle and human α7 nAChRs, expressed in Xenopus laevis oocytes. Thus, our results confirm the utility of the modeling studies on AChBPs in a search for natural compounds with cholinergic activity and demonstrate the presence of the latter in the analyzed marine biological sources.

Differences between epiphytic assemblages on introduced Caulerpa taxifolia and coexisting eelgrass (Zostera capricorni in Botany Bay (NSW, Australia

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Patricia Prado

2008-12-01

Full Text Available A preliminary study was conducted to assess the potential effects of introduced Caulerpa taxifolia (Caulerpales, Chlorophyta on the biodiversity and trophic functioning of seagrass systems in New South Wales, Australia. Epiphytic assemblages growing on fronds of C. taxifolia were compared to those on eelgrass Zostera capricorni (Aschers. leaves in zones where both species were coexisting. The study was conducted at three shallow sites (ca. 1 m depth in Botany Bay during austral spring. Assemblages on both C. taxifolia and Z. capricorni were dominated by epiphytic algae (ca. 65% of the total taxa but results showed significantly greater numbers on C. taxifolia compared to Z. capricorni as well as important differences among study sites. n-MDS ordinations and PERMANOVA analyses confirmed the existence of significant differences in the assemblage compositions of C. taxifolia and Z. capricorni as well as differences between times and sites. SIMPER analysis showed that animal composition made a higher contribution to dissimilarities between habitats compared to epiphytic algae (36% vs. 23% respectively. In particular, filter-feeding organisms, associated with surfaces such as ascidians (5 taxa and bryozoans (2 taxa emerged as important contributing taxa. Hence, our results suggest that introduced C. taxifolia from Botany Bay is a suitable substratum for settlement of epiphytes, at least during the study period, and that observed patterns are due to differences in habitat structure. Further research is necessary to determine the influence of seasonal processes, such as production of toxic secondary metabolites, in other invaded locations of New South Wales.

First description of giant Archaea (Thaumarchaeota) associated with putative bacterial ectosymbionts in a sulfidic marine habitat.

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Muller, Félix; Brissac, Terry; Le Bris, Nadine; Felbeck, Horst; Gros, Olivier

2010-08-01

Archaea may be involved in global energy cycles, and are known for their ability to interact with eukaryotic species (sponges, corals and ascidians) or as archaeal-bacterial consortia. The recently proposed phylum Thaumarchaeota may represent the deepest branching lineage in the archaeal phylogeny emerging before the divergence between Euryarchaeota and Crenarchaeota. Here we report the first characterization of two marine thaumarchaeal species from shallow waters that consist of multiple giant cells. One species is coated with sulfur-oxidizing γ-Proteobacteria. These new uncultured thaumarchaeal species are able to live in the sulfide-rich environments of a tropical mangrove swamp, either on living tissues such as roots or on various kinds of materials such as stones, sunken woods, etc. These archaea and archaea/bacteria associations have been studied using light microscopy, transmission electron microscopy and scanning electron microscopy. Species identification of archaeons and the putative bacterial symbiont have been assessed by 16S small subunit ribosomal RNA analysis. The sulfur-oxidizing ability of the bacteria has been assessed by genetic investigation on alpha-subunit of the adenosine-5'-phosphosulfate reductase/oxidase's (AprA). Species identifications have been confirmed by fluorescence in situ hybridization using specific probes designed in this study. In this article, we describe two new giant archaeal species that form the biggest archaeal filaments ever observed. One of these species is covered by a specific biofilm of sulfur-oxidizing γ-Proteobacteria. This study highlights an unexpected morphological and genetic diversity of the phylum Thaumarchaeota. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Distinct cytoskeleton populations and extensive crosstalk control Ciona notochord tubulogenesis.

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Dong, Bo; Deng, Wei; Jiang, Di

2011-04-01

Cell elongation is a fundamental process that allows cells and tissues to adopt new shapes and functions. During notochord tubulogenesis in the ascidian Ciona intestinalis, a dramatic elongation of individual cells takes place that lengthens the notochord and, consequently, the entire embryo. We find a novel dynamic actin- and non-muscle myosin II-containing constriction midway along the anteroposterior aspect of each notochord cell during this process. Both actin polymerization and myosin II activity are required for the constriction and cell elongation. Discontinuous localization of myosin II in the constriction indicates that the actomyosin network produces local contractions along the circumference. This reveals basal constriction by the actomyosin network as a novel mechanism for cell elongation. Following elongation, the notochord cells undergo a mesenchymal-epithelial transition and form two apical domains at opposite ends. Extracellular lumens then form at the apical surfaces. We show that cortical actin and Ciona ezrin/radixin/moesin (ERM) are essential for lumen formation and that a polarized network of microtubules, which contributes to lumen development, forms in an actin-dependent manner at the apical cortex. Later in notochord tubulogenesis, when notochord cells initiate a bi-directional crawling movement on the notochordal sheath, the microtubule network rotates 90° and becomes organized as parallel bundles extending towards the leading edges of tractive lamellipodia. This process is required for the correct organization of actin-based protrusions and subsequent lumen coalescence. In summary, we establish the contribution of the actomyosin and microtubule networks to notochord tubulogenesis and reveal extensive crosstalk and regulation between these two cytoskeleton components.

Assessment of biofouling community development on test panels submerged in Kudankulam coast with special reference to the Nuclear Power Project

International Nuclear Information System (INIS)

Satheesh, S.; Wesley, S. Godwin

2008-01-01

Biofouling is known to be one of the common problems in cooling water systems of power plants and several incidents of plant shutdown have been reported from various parts of the world. The settlement of marine organisms on an exposed hard surface depends obviously on the species, which are naturally present at a given site as well as their ability to attach and grow on that surface. Information on the organisms forming the fouling complex is necessary in view of the damages they cause to various marine structures and for devising protective measures. The present paper reports the results of the investigations of biofouling carried out for a period of two years from November 2003 to October 2004 at Kudankulam coast where a mega nuclear power project is under construction. Wooden test panels (10x10x3 cm) were fitted to a raft and submerged in the coastal waters. Total fouling biomass, thickness, coverage and community composition were analysed from the panels. Barnacles, mussels, ascidians, polychaetes, amphipods and seaweeds were the common fouling groups settled on the test panels. The total biomass reached to a maximum of 69.9 g.dm -2 (dry weight) after 330 days of exposure. The fouling thickness reached a maximum of 42.3 mm after 225 days of exposure. Results also showed a strong temporal variation in the fouling community recruitment. Based on the observations, Kudankulam coast could be categorized as a moderate fouling station mainly due to the low abundance of mussels in this region. (author)

An efficient method to find potentially universal population genetic markers, applied to metazoans

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Chenuil Anne

2010-09-01

Full Text Available Abstract Background Despite the impressive growth of sequence databases, the limited availability of nuclear markers that are sufficiently polymorphic for population genetics and phylogeography and applicable across various phyla restricts many potential studies, particularly in non-model organisms. Numerous introns have invariant positions among kingdoms, providing a potential source for such markers. Unfortunately, most of the few known EPIC (Exon Primed Intron Crossing loci are restricted to vertebrates or belong to multigenic families. Results In order to develop markers with broad applicability, we designed a bioinformatic approach aimed at avoiding multigenic families while identifying intron positions conserved across metazoan phyla. We developed a program facilitating the identification of EPIC loci which allowed slight variation in intron position. From the Homolens databases we selected 29 gene families which contained 52 promising introns for which we designed 93 primer pairs. PCR tests were performed on several ascidians, echinoderms, bivalves and cnidarians. On average, 24 different introns per genus were amplified in bilaterians. Remarkably, five of the introns successfully amplified in all of the metazoan genera tested (a dozen genera, including cnidarians. The influence of several factors on amplification success was investigated. Success rate was not related to the phylogenetic relatedness of a taxon to the groups that most influenced primer design, showing that these EPIC markers are extremely conserved in animals. Conclusions Our new method now makes it possible to (i rapidly isolate a set of EPIC markers for any phylum, even outside the animal kingdom, and thus, (ii compare genetic diversity at potentially homologous polymorphic loci between divergent taxa.

Isolation and expression of a Pax-6 gene in the regenerating and intact Planarian Dugesia(G)tigrina

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Callaerts, P.; Munoz-Marmol, A. M.; Glardon, S.; Castillo, E.; Sun, H.; Li, W.-H.; Gehring, W. J.; Salo, E.

1999-01-01

The Pax-6 gene encodes a transcription factor containing both a paired and a homeodomain and is highly conserved among Metazoa. In both vertebrates and invertebrates, Pax-6 is required for eye morphogenesis, development of parts of the central nervous system, and, in some phyla, for the development of olfactory sense organs. Ectopic expression of Pax-6 from insects, mammals, cephalopods, and ascidians induces ectopic eyes in Drosophila, suggesting that Pax-6 may be a universal master control gene for eye morphogenesis. Platyhelminthes are an ancient phylum, originating from the base of spiralian protostomes, that bear primitive eyes, consisting of a group of rhabdomeric photoreceptor cells enclosed in a cup of pigment cells. The analysis of Pax-6 and its expression pattern should provide insights into the ancestral function of Pax-6 in eye morphogenesis. We have identified the Pax-6 gene of the planarian Dugesia(G)tigrina (Platyhelminthes; Turbellaria; Tricladida). This gene shares significant sequence identity and conserved genomic organization with Pax-6 proteins from other phyla. Phylogenetic analysis indicates that it clusters with the other Pax-6 genes, but in the most basal position. DtPax-6 is expressed as a single transcript in both regenerating and fully grown eyes, and electron microscopy studies show strong expression in the perykarion of both photoreceptor and pigment cells. Very low levels of expression also are detectable in other body regions. Because a bona fide Pax-6 homolog so far has not been detected in diploblastic animals, we speculate that Pax-6 may be typical for triploblasts and that the appearance of additional Pax genes may have coincided with increasingly complex body plans. PMID:9892672

Discovery and Evaluation of Thiazinoquinones as Anti-Protozoal Agents

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Marcel Kaiser

2013-09-01

Full Text Available Pure compound screening has identified the dioxothiazino-quinoline-quinone ascidian metabolite ascidiathiazone A (2 to be a moderate growth inhibitor of Trypanosoma brucei rhodesiense (IC50 3.1 μM and Plasmodium falciparum (K1 dual drug resistant strain (IC50 3.3 μM while exhibiting low levels of cytotoxicity (L6, IC50 167 μM. A series of C-7 amide and Δ2(3 analogues were prepared that explored the influence of lipophilicity and oxidation state on observed anti-protozoal activity and selectivity. Little variation in anti-malarial potency was observed (IC50 0.62–6.5 μM, and no correlation was apparent between anti-malarial and anti-T. brucei activity. Phenethylamide 7e and Δ2(3-glycine analogue 8k exhibited similar anti-Pf activity to 2 but with slightly enhanced selectivity (SI 72 and 93, respectively, while Δ2(3-phenethylamide 8e (IC50 0.67 μM, SI 78 exhibited improved potency and selectivity towards T. brucei rhodesiense compared to the natural product hit. A second series of analogues were prepared that replaced the quinoline ring of 2 with benzofuran or benzothiophene moieties. While esters 10a/10b and 15 were once again found to exhibit cytotoxicity, carboxylic acid analogues exhibited potent anti-Pf activity (IC50 0.34–0.035 μM combined with excellent selectivity (SI 560–4000. In vivo evaluation of a furan carboxylic acid analogue against P. berghei was undertaken, demonstrating 85.7% and 47% reductions in parasitaemia with ip or oral dosing respectively.

Biofouling of inlet pipes affects water quality in running seawater aquaria and compromises sponge cell proliferation.

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Alexander, Brittany E; Mueller, Benjamin; Vermeij, Mark J A; van der Geest, Harm H G; de Goeij, Jasper M

2015-01-01

Marine organism are often kept, cultured, and experimented on in running seawater aquaria. However, surprisingly little attention is given to the nutrient composition of the water flowing through these systems, which is generally assumed to equal in situ conditions, but may change due to the presence of biofouling organisms. Significantly lower bacterial abundances and higher inorganic nitrogen species (nitrate, nitrite, and ammonium) were measured in aquarium water when biofouling organisms were present within a 7-year old inlet pipe feeding a tropical reef running seawater aquaria system, compared with aquarium water fed by a new, biofouling-free inlet pipe. These water quality changes are indicative of the feeding activity and waste production of the suspension- and filter-feeding communities found in the old pipe, which included sponges, bivalves, barnacles, and ascidians. To illustrate the physiological consequences of these water quality changes on a model organism kept in the aquaria system, we investigated the influence of the presence and absence of the biofouling community on the functioning of the filter-feeding sponge Halisarca caerulea, by determining its choanocyte (filter cell) proliferation rates. We found a 34% increase in choanocyte proliferation rates following the replacement of the inlet pipe (i.e., removal of the biofouling community). This indicates that the physiological functioning of the sponge was compromised due to suboptimal food conditions within the aquarium resulting from the presence of the biofouling organisms in the inlet pipe. This study has implications for the husbandry and performance of experiments with marine organisms in running seawater aquaria systems. Inlet pipes should be checked regularly, and replaced if necessary, in order to avoid excessive biofouling and to approach in situ water quality.

The Use of Filter-feeders to Manage Disease in a Changing World.

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Burge, Colleen A; Closek, Collin J; Friedman, Carolyn S; Groner, Maya L; Jenkins, Cody M; Shore-Maggio, Amanda; Welsh, Jennifer E

2016-10-01

Rapid environmental change is linked to increases in aquatic disease heightening the need to develop strategies to manage disease. Filter-feeding species are effective biofilters and can naturally mitigate disease risk to humans and wildlife. We review the role of filter-feeders, with an emphasis on bivalves, in altering disease outcomes via augmentation and reduction. Filtration can reduce transmission by removing pathogens from the water column via degradation and release of pathogens in pseudofeces. In other cases, filtration can increase pathogen transmission and disease risk. The effect of filtration on pathogen transmission depends on the selectivity of the filter-feeder, the degree of infectivity by the pathogen, the mechanism(s) of pathogen transmission and the ability of the pathogen to resist degradation. For example, some bacteria and viruses can resist degradation and accumulate within a filter-feeder leading to disease transmission to humans and other wildlife upon ingestion. Since bivalves can concentrate microorganisms, they are also useful as sentinels for the presence of pathogenic microorganisms. While somewhat less studied, other invertebrates, including ascidians and sponges may also provide ecosystem services by altering pathogen transmission. In all scenarios, climate change may affect the potential for filter-feeders to mitigate disease risk. We conclude that an assessment including empirical data and modeling of system-wide impacts should be conducted before selection of filter-feeders to mitigate disease. Such studies should consider physiology of the host and microbe and risk factors for negative impacts including augmentation of other pathogens. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

New Mediterranean Biodiversity Records (October, 2014

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S. KATSANEVAKIS

2014-11-01

Full Text Available The Collective Article ‘New Mediterranean Biodiversity Records’ of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article is divided in two parts, for records of alien and native species respectively. The new records of alien species include: the red alga Asparagopsis taxiformis (Crete and Lakonicos Gulf (Greece; the red alga Grateloupia turuturu (along the Israeli Mediterranean shore; the mantis shrimp Clorida albolitura (Gulf of Antalya, Turkey; the mud crab Dyspanopeus sayi (Mar Piccolo of Taranto, Ionian Sea; the blue crab Callinectes sapidus (Chios Island, Greece; the isopod Paracerceis sculpta (northern Aegean Sea, Greece; the sea urchin Diadema setosum (Gökova Bay, Turkey; the molluscs Smaragdia souverbiana, Murex forskoehlii, Fusinus verrucosus, Circenita callipyga, and Aplysia dactylomela (Syria; the cephalaspidean mollusc Haminoea cyanomarginata (Baia di Puolo, Massa Lubrense, Campania, southern Italy; the topmouth gudgeon Pseudorasbora parva (Civitavecchia, Tyrrhenian Sea; the fangtooth moray Enchelycore anatine (Plemmirio marine reserve, Sicily; the silver-cheeked toadfish Lagocephalus sceleratus (Saros Bay, Turkey; and Ibiza channel, Spain; the Indo-Pacific ascidian Herdmania momusin Kastelorizo Island (Greece; and the foraminiferal Clavulina multicam erata (Saronikos Gulf, Greece. The record of L. sceleratus in Spain consists the deepest (350-400m depth record of the species in the Mediterranean Sea. The new records of native species include: first record of the ctenophore Cestum veneris in Turkish marine waters; the presence of Holothuria tubulosa and Holothuria polii in the Bay of Igoumenitsa (Greece; the first recorded sighting of the bull ray Pteromylaeus bovinus in Maltese waters; and a new record of the fish Lobotes surinamensis from Maliakos Gulf.

Evolution of neural crest and placodes: amphioxus as a model for the ancestral vertebrate?

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Holland, L. Z.; Holland, N. D.

2001-01-01

Recent studies of protochordates (ascidian tunicates and amphioxus) have given insights into possible ancestors of 2 of the characteristic features of the vertebrate head: neural crest and placodes. The neural crest probably evolved from cells on either side of the neural plate-epidermis boundary in a protochordate ancestral to the vertebrates. In amphioxus, homologues of several vertebrate neural crest marker genes (BMP2/4, Pax3/7, Msx, Dll and Snail) are expressed at the edges of the neural plate and/or adjacent nonneural ectoderm. Some of these markers are also similarly expressed in tunicates. In protochordates, however, these cells, unlike vertebrate neural crest, neither migrate as individuals through embryonic tissues nor differentiate into a wide spectrum of cell types. Therefore, while the protochordate ancestor of the vertebrates probably had the beginnings of a genetic programme for neural crest formation, this programme was augmented in the earliest vertebrates to attain definitive neural crest. Clear homologues of vertebrate placodes are lacking in protochordates. However, both amphioxus and tunicates have ectodermal sensory cells. In tunicates these are all primary neurons, sending axons to the central nervous system, while in amphioxus, the ectodermal sensory cells include both primary neurons and secondary neurons lacking axons. Comparisons of developmental gene expression suggest that the anterior ectoderm in amphioxus may be homologous to the vertebrate olfactory placode, the only vertebrate placode with primary, not secondary, neurons. Similarly, biochemical, morphological and gene expression data suggest that amphioxus and tunicates also have homologues of the adenohypophysis, one of the few vertebrate structures derived from nonneurogenic placodes. In contrast, the origin of the other vertebrate placodes is very uncertain.

A single and rapid calcium wave at egg activation in Drosophila

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Anna H. York-Andersen

2015-03-01

Full Text Available Activation is an essential process that accompanies fertilisation in all animals and heralds major cellular changes, most notably, resumption of the cell cycle. While activation involves wave-like oscillations in intracellular Ca2+ concentration in mammals, ascidians and polychaete worms and a single Ca2+ peak in fish and frogs, in insects, such as Drosophila, to date, it has not been shown what changes in intracellular Ca2+ levels occur. Here, we utilise ratiometric imaging of Ca2+ indicator dyes and genetically encoded Ca2+ indicator proteins to identify and characterise a single, rapid, transient wave of Ca2+ in the Drosophila egg at activation. Using genetic tools, physical manipulation and pharmacological treatments we demonstrate that the propagation of the Ca2+ wave requires an intact actin cytoskeleton and an increase in intracellular Ca2+ can be uncoupled from egg swelling, but not from progression of the cell cycle. We further show that mechanical pressure alone is not sufficient to initiate a Ca2+ wave. We also find that processing bodies, sites of mRNA decay and translational regulation, become dispersed following the Ca2+ transient. Based on this data we propose the following model for egg activation in Drosophila: exposure to lateral oviduct fluid initiates an increase in intracellular Ca2+ at the egg posterior via osmotic swelling, possibly through mechano-sensitive Ca2+ channels; a single Ca2+ wave then propagates in an actin dependent manner; this Ca2+ wave co-ordinates key developmental events including resumption of the cell cycle and initiation of translation of mRNAs such as bicoid.

An expanded Notch-Delta model exhibiting long-range patterning and incorporating MicroRNA regulation.

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Jerry S Chen

2014-06-01

Full Text Available Notch-Delta signaling is a fundamental cell-cell communication mechanism that governs the differentiation of many cell types. Most existing mathematical models of Notch-Delta signaling are based on a feedback loop between Notch and Delta leading to lateral inhibition of neighboring cells. These models result in a checkerboard spatial pattern whereby adjacent cells express opposing levels of Notch and Delta, leading to alternate cell fates. However, a growing body of biological evidence suggests that Notch-Delta signaling produces other patterns that are not checkerboard, and therefore a new model is needed. Here, we present an expanded Notch-Delta model that builds upon previous models, adding a local Notch activity gradient, which affects long-range patterning, and the activity of a regulatory microRNA. This model is motivated by our experiments in the ascidian Ciona intestinalis showing that the peripheral sensory neurons, whose specification is in part regulated by the coordinate activity of Notch-Delta signaling and the microRNA miR-124, exhibit a sparse spatial pattern whereby consecutive neurons may be spaced over a dozen cells apart. We perform rigorous stability and bifurcation analyses, and demonstrate that our model is able to accurately explain and reproduce the neuronal pattern in Ciona. Using Monte Carlo simulations of our model along with miR-124 transgene over-expression assays, we demonstrate that the activity of miR-124 can be incorporated into the Notch decay rate parameter of our model. Finally, we motivate the general applicability of our model to Notch-Delta signaling in other animals by providing evidence that microRNAs regulate Notch-Delta signaling in analogous cell types in other organisms, and by discussing evidence in other organisms of sparse spatial patterns in tissues where Notch-Delta signaling is active.

Screening of ovarian steroidogenic pathway in Ciona intestinalis and its modulation after tributyltin exposure

International Nuclear Information System (INIS)

Cangialosi, Maria Vittoria; Puccia, Egidio; Mazzola, Antonio; Mansueto, Valentina; Arukwe, Augustine

2010-01-01

In this study, we have identified several ovarian steroids in Ciona with high similarity to vertebrate steroids and showed that cholesterol, corticosterone, dehydroepiandrosterone, estrone, estradiol-17β, testosterone, pregnenolone, progesterone, have identical molecular spectra with vertebrate steroids. In addition, we have studied the effects of an endocrine disruptor (tributyltin: TBT) on these sex hormones and their precursors, ovarian morphology, and gene expression of some key enzymes in steroidogenic pathway in the ovary of Ciona. Ovarian specimens were cultured in vitro using different concentrations of TBT (10 -5 , 10 -4 and 10 -3 M). Ethanol was used as solvent control. Gene expression analysis was performed for adrenodoxin (ADREN) and adrenodoxin reductase (ADOX) (mediators of acute steroidogenesis) and 17β-hydroxysteroid dehydrogenase (17β-HSD). These transcripts were detected and measured by quantitative (real-time) polymerase chain reaction (qPCR). Sex steroids and their precursors were identified and quantified by a gas chromatography-mass spectroscopy (GC-MS) method. Exposure of Ciona ovaries to TBT produced modulations (either increased or decreased) of sterols and sex steroid levels, whereas no significant differences in ADREN, ADOX or 17β-HSD mRNA expression patterns were observed. Histological analysis shows that TBT produced several modifications on Ciona ovarian morphology that includes irregular outline of nuclear membrane, less compacted cytoplasm, in addition to test and granulosa cells that were detached from the oocyte membrane. Given that the ascidians represent very simple experimental models for the study of endocrine disruption by environmental contaminants, our findings provide excellent models for multiple identification and quantification of sex steroid and their precursors in biological samples exposed to endocrine-disrupting chemicals and for direct extrapolation of such effects across taxonomic groups and phyla. In addition

The substantial first impact of bottom fishing on rare biodiversity hotspots: a dilemma for evidence-based conservation.

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Cook, Robert; Fariñas-Franco, Jose M; Gell, Fiona R; Holt, Rohan H F; Holt, Terry; Lindenbaum, Charles; Porter, Joanne S; Seed, Ray; Skates, Lucie R; Stringell, Thomas B; Sanderson, William G

2013-01-01

This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a 'priority habitat' the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive) as well as indicators of 'Good Environmental Status' under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.

In the ovary of Ciona intestinalis (Type A), immune-related galectin and phenoloxidase genes are differentially expressed by the follicle accessory cells.

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Parrinello, Daniela; Sanfratello, Maria Antonietta; Parisi, Maria Giovanna; Vizzini, Aiti; Cammarata, Matteo

2018-01-01

Riboprobes (in situ hybridization) and antibodies (immunohistochemistry), previously used to show the upregulation of Ciona intestinalis (Type A) galectins (CiLgals-a, CiLgals-b) and phenoloxidase (CinPO2) immune-related genes, were tested on histological sections of the ovary. The ovarian follicles are composed of oocytes encased by follicular cells (FCs) and test cells (TCs). Results show the transcription upregulation of both CiLgals and CinPO2 genes in the vitellogenic FCs, conversely distinct cytolocalization of the proteins are shown. At vitellogenic stage, the CiLgals are localized in the FCs, in the oocyte cytoplasm, and close to the germinal vesicle (GV), whereas the CinPO2 was never identified in the FCs. In a presumptive advanced phase and at the post-vitellogenic stage the TCs appear to be labelled by the CinPO2 riboprobe, and the protein identified by the antibody suggesting an mRNA transcytosis process from FCs. At post-vitellogenic stage the CiLgals mainly enrich the GV nucleoplasm, whereas the CinPO2 is contained in TCs and in the ooplasm but never found in the GV. This finding sheds new light on a former paper in which TCs were reported to be the only CinPO2-producing cells in the ovarian follicle. Finally, CiLgals and CinPO2 genes transcription and proteins production seem to be associated with accessory cells during their differentiation from vitellogenic to post-vitellogenic stage. The present findings promote further research on the early upregulation of immune-related genes, and the potential multifunctional role of the produced proteins. In addition further insight on the accessory cells involvement in ascidian oogenesis are reported. Copyright © 2017 Elsevier Ltd. All rights reserved.

Animal egg as evolutionary innovation: a solution to the "embryonic hourglass" puzzle.

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Newman, Stuart A

2011-11-15

The evolutionary origin of the egg stage of animal development presents several difficulties for conventional developmental and evolutionary narratives. If the egg's internal organization represents a template for key features of the developed organism, why can taxa within a given phylum exhibit very different egg types, pass through a common intermediate morphology (the so-called "phylotypic stage"), only to diverge again, thus exemplifying the embryonic "hourglass"? Moreover, if different egg types typically represent adaptations to different environmental conditions, why do birds and mammals, for example, have such vastly different eggs with respect to size, shape, and postfertilization dynamics, whereas all these features are more similar for ascidians and mammals? Here, I consider the possibility that different body plans had their origin in self-organizing physical processes in ancient clusters of cells, and suggest that eggs represented a set of independent evolutionary innovations subsequently inserted into the developmental trajectories of such aggregates. I first describe how "dynamical patterning modules" (DPMs) associations between components of the metazoan developmental-genetic toolkit and certain physical processes and effects may have organized primitive animal body plans independently of an egg stage. Next, I describe how adaptive specialization of cells released from such aggregates could have become "proto-eggs," which regenerated the parental cell clusters by cleavage, conserving the characteristic DPMs available to a lineage. Then, I show how known processes of cytoplasmic reorganization following fertilization are often based on spontaneous, self-organizing physical effects ("egg-patterning processes": EPPs). I suggest that rather than acting as developmental blueprints or prepatterns, the EPPs refine the phylotypic body plans determined by the DPMs by setting the boundary and initial conditions under which these multicellular patterning

Energetics of the Ventilatory Piston Pump of the Lugworm, a Deposit-feeding Polychaete Living in a Burrow.

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Toulmond, A; Dejours, P

1994-04-01

The aim of this study was to tentatively estimate the energy cost of breathing in the lugworm, Arenicola marina (L.), a gallery-dwelling, piston-pump breather that moves water in a tail-to-head direction. Each tested lugworm was placed in a horizontal glass tube. The caudal end of the tube was connected to a well-aerated seawater reservoir at 20{deg}C, and the cephalic end attached to a drop meter through a tube resistance. At the exit of the cephalic chamber the O2 tension was recorded via an in situ O2 electrode, and the hydrostatic pressure of the exhaled water was also recorded. Water flow rate, total O2 uptake rate {Mdot}TOTO2, O2 extraction coefficient, and the mechanical power necessary to pump water through the resistive anterior exit of the apparatus ({Wdot}MEC), were computed. The basal metabolic rate of each animal ({Mdot}CONFO2) was separately estimated by the confinement method. {Mdot}CONFO2 subtracted from {Mdot}TOTO2 approximates {Mdot}CBO2, the O2 uptake rate necessary to activate the piston-pump breathing mechanism and to ensure the corresponding mechanical work rate, {Wdot}MEC. The results show that the energy cost of breathing, {Mdot}CBO2, of the piston-pump-breathing Arenicola is very high, with mean values approximating 47% of the {Mdot}TOTO2 value; that the mechanical power we measured, {Wdot}MEC, is very low; and that the mechanical-to-metabolic efficiency, the ratio {Wdot}MEC/{Mdot}CBO2, does not exceed 1%. These observations are compared to those obtained in other piston-pump breathers, such as Chaetopterus variopedatus and Urechis caupo, and in ciliary filter feeders including polychaetes, bivalves, and ascidians.

Rubrolides as model for the development of new lactones and their aza analogs as potential photosynthesis inhibitors.

Science.gov (United States)

Pereira, Ulisses A; Barbosa, Luiz C A; Demuner, Antônio J; Silva, Antônio A; Bertazzini, Michele; Forlani, Giuseppe

2015-07-01

Natural phytotoxins and their synthetic analogs are a potential source of new bioactive compounds for agriculture. Analogs of rubrolides, a class of γ-alkylidene-γ-lactones isolated from different ascidians, have been shown to interfere with the photosynthetic electron-transport chain, yet their activity needs to be improved. With this aim, ten 5-aryl-6-benzyl-4-bromopyridazin-3(2H)-ones were prepared in yields ranging from 44 to 88% by reaction of their correspondent γ-alkylidene-γ-lactones with NH2 NH2 . The structures of these rubrolide analogs were determined by (1) H- and (13) C-NMR, 2D-NMR (COSY and HETCOR), NOE difference, and MS techniques. These compounds were evaluated for their abilities of interfering with the light-driven reduction of ferricyanide by isolated spinach chloroplasts. Lactones with electron-withdrawing substituents in the para-position of the benzylidene ring were the most effective inhibitors. Characterization of the activity of 11b/11b' suggested a mechanism based on the interaction with the plastoquinone binding site of photosystem II. Addition of several compounds to the culture medium of a cyanobacterial model strain was found to inhibit algal growth. However, the relative effectiveness was not consistent with their activity in vitro, suggesting the occurrence of multiple targets and/or detoxyfication mechanisms. Indeed, the compounds showed differential effects on the heterotrophic growth of some crop species, Cucumis sativus and Sorghum bicolor. Pyridazin-3(2H)-ones 12e, 12i, and 12j, which have been found poorly active against the photosynthetic electron transport, were the most effective in inhibiting the growth of some weeds, Ipomoea grandifolia and Brachiaria decumbens, under greenhouse conditions. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Biofouling of inlet pipes affects water quality in running seawater aquaria and compromises sponge cell proliferation

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Brittany E. Alexander

2015-12-01

Full Text Available Marine organism are often kept, cultured, and experimented on in running seawater aquaria. However, surprisingly little attention is given to the nutrient composition of the water flowing through these systems, which is generally assumed to equal in situ conditions, but may change due to the presence of biofouling organisms. Significantly lower bacterial abundances and higher inorganic nitrogen species (nitrate, nitrite, and ammonium were measured in aquarium water when biofouling organisms were present within a 7-year old inlet pipe feeding a tropical reef running seawater aquaria system, compared with aquarium water fed by a new, biofouling-free inlet pipe. These water quality changes are indicative of the feeding activity and waste production of the suspension- and filter-feeding communities found in the old pipe, which included sponges, bivalves, barnacles, and ascidians. To illustrate the physiological consequences of these water quality changes on a model organism kept in the aquaria system, we investigated the influence of the presence and absence of the biofouling community on the functioning of the filter-feeding sponge Halisarca caerulea, by determining its choanocyte (filter cell proliferation rates. We found a 34% increase in choanocyte proliferation rates following the replacement of the inlet pipe (i.e., removal of the biofouling community. This indicates that the physiological functioning of the sponge was compromised due to suboptimal food conditions within the aquarium resulting from the presence of the biofouling organisms in the inlet pipe. This study has implications for the husbandry and performance of experiments with marine organisms in running seawater aquaria systems. Inlet pipes should be checked regularly, and replaced if necessary, in order to avoid excessive biofouling and to approach in situ water quality.

Tough Adults, Frail Babies: An Analysis of Stress Sensitivity across Early Life-History Stages of Widely Introduced Marine Invertebrates

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Pineda, M. Carmen; McQuaid, Christopher D.; Turon, Xavier; López-Legentil, Susanna; Ordóñez, Víctor; Rius, Marc

2012-01-01

All ontogenetic stages of a life cycle are exposed to environmental conditions so that population persistence depends on the performance of both adults and offspring. Most studies analysing the influence of abiotic conditions on species performance have focussed on adults, while studies covering early life-history stages remain rare. We investigated the responses of early stages of two widely introduced ascidians, Styela plicata and Microcosmus squamiger, to different abiotic conditions. Stressors mimicked conditions in the habitats where both species can be found in their distributional ranges and responses were related to the selection potential of their populations by analysing their genetic diversity. Four developmental stages (egg fertilisation, larval development, settlement, metamorphosis) were studied after exposure to high temperature (30°C), low salinities (26 and 22‰) and high copper concentrations (25, 50 and 100 µg/L). Although most stressors effectively led to failure of complete development (fertilisation through metamorphosis), fertilisation and larval development were the most sensitive stages. All the studied stressors affected the development of both species, though responses differed with stage and stressor. S. plicata was overall more resistant to copper, and some stages of M. squamiger to low salinities. No relationship was found between parental genetic composition and responses to stressors. We conclude that successful development can be prevented at several life-history stages, and therefore, it is essential to consider multiple stages when assessing species' abilities to tolerate stress. Moreover, we found that early development of these species cannot be completed under conditions prevailing where adults live. These populations must therefore recruit from elsewhere or reproduce during temporal windows of more benign conditions. Alternatively, novel strategies or behaviours that increase overall reproductive success might be

The substantial first impact of bottom fishing on rare biodiversity hotspots: a dilemma for evidence-based conservation.

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Robert Cook

Full Text Available This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.. One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90% or scallop dredge (59%, as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a 'priority habitat' the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive as well as indicators of 'Good Environmental Status' under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.

An assessment of contamination of the Fusaro Lagoon (Campania Province, southern Italy) by trace metals.

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Arienzo, M; Toscano, F; Di Fraia, M; Caputi, L; Sordino, P; Guida, M; Aliberti, F; Ferrara, L

2014-09-01

The Fusaro Lagoon is a shallow lagoon, located in SW Italy, largely influenced in the last decades by several anthropic impacts. The study examined the pollution status of the lagoon, during year 2011-2012 at nine sampling stations with the aim to find out proper measurements of water lagoon restoration. Concentrations of heavy metals (HMs) (aluminium [Al], barium [Ba], cadmium [Cd], copper [Cu], iron [Fe], manganese [Mn], vanadium [V] and zinc [Zn]) were examined in water, sediments and specimens of the ascidian Ciona intestinalis sp. A. Low levels of dissolved oxygen concentration were detected at many stations, with mean values of 5.2-6.4 mg L(-1). The redox potential of surface waters was also low, -2.7 to 50.7 mV. Sediments possessed high organic matter content, 17.7-29.4%. In sediments, the mean Zn level, 251.4 mg kg(-1), was about sixfold higher than that recorded in year 2000 (38.5 mg kg(-1)) and considerably higher than that recorded in 2007 (191 mg kg(-1)). The mean levels of Cd were outstandingly high, with a mean value of 70.5 mg kg(-1), about 30- and 50-fold higher than those determined in 2000 and 2007, respectively. Cadmium (Cd), Cu and nickel (Ni) appeared in excess with respect to most current guidelines, reaching significant pollution levels. C. intestinalis sp. A was detected only at few stations, with metals accumulated preferentially in the body in respect to the tunic, from 1.2 times for Zn (178 mg kg(-1)) to 4.0 times for V (304 mg kg(-1)). Data suggests the necessity of an immediate action of eco-compatible interventions for environmental restoration.

Tough adults, frail babies: an analysis of stress sensitivity across early life-history stages of widely introduced marine invertebrates.

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M Carmen Pineda

Full Text Available All ontogenetic stages of a life cycle are exposed to environmental conditions so that population persistence depends on the performance of both adults and offspring. Most studies analysing the influence of abiotic conditions on species performance have focussed on adults, while studies covering early life-history stages remain rare. We investigated the responses of early stages of two widely introduced ascidians, Styela plicata and Microcosmus squamiger, to different abiotic conditions. Stressors mimicked conditions in the habitats where both species can be found in their distributional ranges and responses were related to the selection potential of their populations by analysing their genetic diversity. Four developmental stages (egg fertilisation, larval development, settlement, metamorphosis were studied after exposure to high temperature (30°C, low salinities (26 and 22‰ and high copper concentrations (25, 50 and 100 µg/L. Although most stressors effectively led to failure of complete development (fertilisation through metamorphosis, fertilisation and larval development were the most sensitive stages. All the studied stressors affected the development of both species, though responses differed with stage and stressor. S. plicata was overall more resistant to copper, and some stages of M. squamiger to low salinities. No relationship was found between parental genetic composition and responses to stressors. We conclude that successful development can be prevented at several life-history stages, and therefore, it is essential to consider multiple stages when assessing species' abilities to tolerate stress. Moreover, we found that early development of these species cannot be completed under conditions prevailing where adults live. These populations must therefore recruit from elsewhere or reproduce during temporal windows of more benign conditions. Alternatively, novel strategies or behaviours that increase overall reproductive success

Selective suppression of in situ proliferation of scyphozoan polyps by biofouling.

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Feng, Song; Wang, Shi-Wei; Zhang, Guang-Tao; Sun, Song; Zhang, Fang

2017-01-30

An increase in marine artificial constructions has been proposed as a major cause of jellyfish blooms, because these constructions provide additional substrates for organisms at the benthic stage (polyps), which proliferate asexually and release a large amount of free-swimming medusae. These hard surfaces are normally covered by fouling communities, the components of which have the potential to impede the proliferation of polyps. In this study, we report an in situ experiment of polyp survival of four large scyphozoan species found in East Asian marginal seas that were exposed to biofouling, a universal phenomenon occurring on marine artificial constructions. Our results showed that the polyps of three species (Nemopilema nomurai, Cyanea nozaki, and Rhopilema esculentum) attached to the artificial surfaces were completely eliminated by biofouling within 7-8months, and only those of moon jellyfish (Aurelia sp.1) in the upper layers could multiply on both artificial materials and other organisms (e.g., ascidians and bryozoans). Fouling-associated competition and predation and suppressed asexual reproduction of podocysts were observed to contribute to the loss of polyps. This study shows that the natural distribution of polyps is defined by the biofouling community that colonizes the surfaces of artificial constructions. Consequently, the contribution of marine constructions to jellyfish bloom is limited only to the ability of the jellyfish species to reproduce asexually through budding and inhabit solid surfaces of fouling organisms in addition to inhabiting original artificial materials. We anticipate that fragile polyps will colonize and proliferate in harsh environments that are deleterious to biofouling, and we propose special attention to polyps in antifouling practices for excluding the possibility that they occupy the available ecological space. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ocean acidification alters early successional coral reef communities and their rates of community metabolism.

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Sam H C Noonan

Full Text Available Ocean acidification is expected to alter community composition on coral reefs, but its effects on reef community metabolism are poorly understood. Here we document how early successional benthic coral reef communities change in situ along gradients of carbon dioxide (CO2, and the consequences of these changes on rates of community photosynthesis, respiration, and light and dark calcification. Ninety standardised benthic communities were grown on PVC tiles deployed at two shallow-water volcanic CO2 seeps and two adjacent control sites in Papua New Guinea. Along the CO2 gradient, both the upward facing phototrophic and the downward facing cryptic communities changed in their composition. Under ambient CO2, both communities were dominated by calcifying algae, but with increasing CO2 they were gradually replaced by non-calcifying algae (predominantly green filamentous algae, cyanobacteria and macroalgae, which increased from ~30% to ~80% cover. Responses were weaker in the invertebrate communities, however ascidians and tube-forming polychaetes declined with increasing CO2. Differences in the carbonate chemistry explained a far greater amount of change in communities than differences between the two reefs and successional changes from five to 13 months, suggesting community successions are established early and are under strong chemical control. As pH declined from 8.0 to 7.8, rates of gross photosynthesis and dark respiration of the 13-month old reef communities (upper and cryptic surfaces combined significantly increased by 10% and 20%, respectively, in response to altered community composition. As a consequence, net production remained constant. Light and dark calcification rates both gradually declined by 20%, and low or negative daily net calcification rates were observed at an aragonite saturation state of <2.3. The study demonstrates that ocean acidification as predicted for the end of this century will strongly alter reef communities, and

Selective suppression of in situ proliferation of scyphozoan polyps by biofouling

International Nuclear Information System (INIS)

Feng, Song; Wang, Shi-Wei; Zhang, Guang-Tao; Sun, Song; Zhang, Fang

2017-01-01

An increase in marine artificial constructions has been proposed as a major cause of jellyfish blooms, because these constructions provide additional substrates for organisms at the benthic stage (polyps), which proliferate asexually and release a large amount of free-swimming medusae. These hard surfaces are normally covered by fouling communities, the components of which have the potential to impede the proliferation of polyps. In this study, we report an in situ experiment of polyp survival of four large scyphozoan species found in East Asian marginal seas that were exposed to biofouling, a universal phenomenon occurring on marine artificial constructions. Our results showed that the polyps of three species (Nemopilema nomurai, Cyanea nozaki, and Rhopilema esculentum) attached to the artificial surfaces were completely eliminated by biofouling within 7–8 months, and only those of moon jellyfish (Aurelia sp.1) in the upper layers could multiply on both artificial materials and other organisms (e.g., ascidians and bryozoans). Fouling-associated competition and predation and suppressed asexual reproduction of podocysts were observed to contribute to the loss of polyps. This study shows that the natural distribution of polyps is defined by the biofouling community that colonizes the surfaces of artificial constructions. Consequently, the contribution of marine constructions to jellyfish bloom is limited only to the ability of the jellyfish species to reproduce asexually through budding and inhabit solid surfaces of fouling organisms in addition to inhabiting original artificial materials. We anticipate that fragile polyps will colonize and proliferate in harsh environments that are deleterious to biofouling, and we propose special attention to polyps in antifouling practices for excluding the possibility that they occupy the available ecological space. - Highlights: • Biofouling selectively controls in situ proliferation of scyphozoan polyps • The contribution

Differential responses of emergent intertidal coral reef fauna to a large-scale El-Niño southern oscillation event: sponge and coral resilience.

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Kelmo, Francisco; Bell, James J; Moraes, Simone Souza; Gomes, Rilza da Costa Tourinho; Mariano-Neto, Eduardo; Attrill, Martin J

2014-01-01

There is a paucity of information on the impacts of the 1997-8 El Niño event and subsequent climatic episodes on emergent intertidal coral reef assemblages. Given the environmental variability intertidal reefs experience, such reefs may potentially be more resilient to climatic events and provide important insights into the adaptation of reef fauna to future ocean warming. Here we report the results of a 17-year (1995-2011) biodiversity survey of four emergent coral reef ecosystems in Bahia, Brazil, to assess the impact of a major El Niño event on the reef fauna, and determine any subsequent recovery. The densities of two species of coral, Favia gravida and Siderastrea stellata, did not vary significantly across the survey period, indicating a high degree of tolerance to the El Niño associated stress. However, there were marked decreases in the diversity of other taxa. Molluscs, bryozoans and ascidians suffered severe declines in diversity and abundance and had not recovered to pre-El Niño levels by the end of the study. Echinoderms were reduced to a single species in 1999, Echinometra lucunter, although diversity levels had recovered by 2002. Sponge assemblages were not impacted by the 1997-8 event and their densities had increased by the study end. Multivariate analysis indicated that a stable invertebrate community had re-established on the reefs after the El Niño event, but it has a different overall composition to the pre-El Niño community. It is unclear if community recovery will continue given more time, but our study highlights that any increase in the frequency of large-scale climatic events to more than one a decade is likely to result in a persistent lower-diversity state. Our results also suggest some coral and sponge species are particularly resilient to the El Niño-associated stress and therefore represent suitable models to investigate temperature adaptation in reef organisms.

A review of contemporary patterns of endemism for shallow water reef fauna in the Red Sea

KAUST Repository

DiBattista, Joseph

2015-11-03

Aim The Red Sea is characterised by a unique fauna and historical periods of desiccation, hypersalinity and intermittent isolation. The origin and contemporary composition of reef-associated taxa in this region can illuminate biogeographical principles about vicariance and the establishment (or local extirpation) of existing species. Here we aim to: (1) outline the distribution of shallow water fauna between the Red Sea and adjacent regions, (2) explore mechanisms for maintaining these distributions and (3) propose hypotheses to test these mechanisms. Location Red Sea, Gulf of Aden, Arabian Sea, Arabian Gulf and Indian Ocean. Methods Updated checklists for scleractinian corals, fishes and non-coral invertebrates were used to determine species richness in the Red Sea and the rest of the Arabian Peninsula and assess levels of endemism. Fine-scale diversity and abundance of reef fishes within the Red Sea were explored using ecological survey data. Results Within the Red Sea, we recorded 346 zooxanthellate and azooxanthellate scleractinian coral species of which 19 are endemic (5.5%). Currently 635 species of polychaetes, 211 echinoderms and 79 ascidians have been documented, with endemism rates of 12.6%, 8.1% and 16.5% respectively. A preliminary compilation of 231 species of crustaceans and 137 species of molluscs include 10.0% and 6.6% endemism respectively. We documented 1071 shallow fish species, with 12.9% endemic in the entire Red Sea and 14.1% endemic in the Red Sea and Gulf of Aden. Based on ecological survey data of endemic fishes, there were no major changes in species richness or abundance across 1100 km of Saudi Arabian coastline. Main conclusions The Red Sea biota appears resilient to major environmental fluctuations and is characterized by high rates of endemism with variable degrees of incursion into the Gulf of Aden. The nearby Omani and Arabian Gulfs also have variable environments and high levels of endemism, but these are not consistently distinct

Evolutionary diversification of secondary mechanoreceptor cells in tunicata.

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Rigon, Francesca; Stach, Thomas; Caicci, Federico; Gasparini, Fabio; Burighel, Paolo; Manni, Lucia

2013-06-04

Hair cells are vertebrate secondary sensory cells located in the ear and in the lateral line organ. Until recently, these cells were considered to be mechanoreceptors exclusively found in vertebrates that evolved within this group. Evidence of secondary mechanoreceptors in some tunicates, the proposed sister group of vertebrates, has recently led to the hypothesis that vertebrate and tunicate secondary sensory cells share a common origin. Secondary sensory cells were described in detail in two tunicate groups, ascidians and thaliaceans, in which they constitute an oral sensory structure called the coronal organ. Among thaliaceans, the organ is absent in salps and it has been hypothesised that this condition is due to a different feeding system adopted by this group of animals. No information is available as to whether a comparable structure exists in the third group of tunicates, the appendicularians, although different sensory structures are known to be present in these animals. We studied the detailed morphology of appendicularian oral mechanoreceptors. Using light and electron microscopy we could demonstrate that the mechanosensory organ called the circumoral ring is composed of secondary sensory cells. We described the ultrastructure of the circumoral organ in two appendicularian species, Oikopleura dioica and Oikopleura albicans, and thus taxonomically completed the data collection of tunicate secondary sensory cells. To understand the evolution of secondary sensory cells in tunicates, we performed a cladistic analysis using morphological data. We constructed a matrix consisting of 19 characters derived from detailed ultrastructural studies in 16 tunicate species and used a cephalochordate and three vertebrate species as outgroups. Our study clearly shows that the circumoral ring is the appendicularian homologue of the coronal organ of other tunicate taxa. The cladistic analysis enabled us to reconstruct the features of the putative ancestral hair cell in

Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communities.

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Brown, Norah E M; Milazzo, Marco; Rastrick, Samuel P S; Hall-Spencer, Jason M; Therriault, Thomas W; Harley, Christopher D G

2018-01-01

Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO 2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO 2 change and, if high pCO 2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO 2 stress, or are worsened by departures from prior high pCO 2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments along a shallow water volcanic pCO 2 gradient to assess the importance of the timing and duration of high pCO 2 exposure (i.e., discrete events at different stages of successional development vs. continuous exposure) on patterns of colonization and succession in a benthic fouling community. We show that succession at the acidified site was initially delayed (less community change by 8 weeks) but then caught up over the next 4 weeks. These changes in succession led to homogenization of communities maintained in or transplanted to acidified conditions, and altered community structure in ways that reflected both short- and longer-term acidification history. These community shifts are likely a result of interspecific variability in response to increased pCO 2 and changes in species interactions. High pCO 2 altered biofilm development, allowing serpulids to do best at the acidified site by the end of the experiment, although early (pretransplant) negative effects of pCO 2 on recruitment of these worms were still detectable. The ascidians Diplosoma sp. and Botryllus sp. settled later and were more tolerant to acidification. Overall, transient and persistent acidification-driven changes in the biofouling community, via both past and more recent exposure, could have important

Physical properties of the tunic in the pinkish-brown salp Pegea confoederata (Tunicata: Thaliacea).

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Sakai, Daisuke; Kakiuchida, Hiroshi; Nishikawa, Jun; Hirose, Euichi

2018-01-01

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. 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  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. 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

The evolution of Msx gene function: expression and regulation of a sea urchin Msx class homeobox gene.

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Dobias, S L; Ma, L; Wu, H; Bell, J R; Maxson, R

1997-01-01

Msx- class homeobox genes, characterized by a distinct and highly conserved homeodomain, have been identified in a wide variety of metazoans from vertebrates to coelenterates. Although there is evidence that they participate in inductive tissue interactions that underlie vertebrate organogenesis, including those that pattern the neural crest, there is little information about their function in simple deuterostomes. Both to learn more about the ancient function of Msx genes, and to shed light on the evolution of developmental mechanisms within the lineage that gave rise to vertebrates, we have isolated and characterized Msx genes from ascidians and echinoderms. Here we describe the sequence and expression of a sea urchin (Strongylocentrotus purpouratus) Msx gene whose homeodomain is very similar to that of vertebrate Msx2. This gene, designated SpMsx, is first expressed in blastula stage embryos, apparently in a non-localized manner. Subsequently, during the early phases of gastrulation, SpMsx transcripts are expressed intensely in the invaginating archenteron and secondary mesenchyme, and at reduced levels in the ectoderm. In the latter part of gastrulation, SpMsx transcripts are concentrated in the oral ectoderm and gut, and continue to be expressed at those sites through the remainder of embryonic development. That vertebrate Msx genes are regulated by inductive tissue interactions and growth factors suggested to us that the restriction of SpMsx gene expression to the oral ectoderm and derivatives of the vegetal plate might similarly be regulated by the series of signaling events that pattern these embryonic territories. As a first test of this hypothesis, we examined the influence of exogastrulation and cell-dissociation on SpMsx gene expression. In experimentally-induced exogastrulae, SpMsx transcripts were distributed normally in the oral ectoderm, evaginated gut, and secondary mesenchyme. However, when embryos were dissociated into their component cells, Sp

Distribución de Ecteinascidia turbinata (Ascidiacea: Perophoridae en los manglares de la Península de Yucatán, México

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José Luis Carballo

2000-06-01

Full Text Available La ascidia Ecteinascidia turbinata sintetiza un grupo de moléculas consideradas hoy en día como unas de las más prometedoras contra diversos tipos de tumores. Sin embargo, la síntesis de este compuesto todavía no se ha podido conseguir químicamente, y la única fuente de producto activo la constituye las poblaciones naturales de este tunicado, el cual se cultiva o colecta en distintas partes del mundo para la obtención del producto activo. Con este trabajo, se ha intentado hacer una valoración preliminar de la población de E. turbinata en el Golfo de México y Península de Yucatán. Se muestrearon 33 localidades, desde el Estado de Veracruz en el Golfo de México, hasta Quintana Roo en el Caribe. Parece que la especie está bien establecida en la Península de Yucatán; sobre todo en el Mar Caribe, aunque se trata de poblaciones discontinuas y separadas geográficamente. Entre todas las localidades prospectadas, solo en Río Lagartos situada al Norte de la Península de Yucatán, se detectaron poblaciones con densidades próximas a 1 colonia/metro margen de manglar, y una producción media de 115 g de biomasa por metro lineal de manglar, que podría ofrecer posibilidades para establecer un programa de manejo del recurso de manera sustentable.The ascidian Ecteinascidia turbinata synthesizes some of the most promising substances against solid-type tumors, but the only available source are the natural populations of this tunicate, which is reared or collected in different parts of the world. A total of 33 locations were sampled in the Gulf of Mexico and the Yucatan Peninsula. The tunicate was not found in Veracruz, Tabasco and Campeche, but it was well established on mangrove roots in the Yucatan Peninsula where we estimated densities more or less equal to one colony and an average production of 115 g of biomass per lineal meter of mangrove coastline in one location (Río Lagartos. Sustainable management appears to be possible.

Alimentación de la ascidia Ecteinascidia turbinata (Ascidiacea: Perophoridae en dos áreas de manglar de Cuba

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Aida Hernández-Zanuy

2007-06-01

Full Text Available Se estudiaron los contenidos estomacales de 88 zooides de Ecteinascidia turbinata Herdman 1880 y la composición cualitativa y cuantitativa del fitoplancton en la columna de agua en Santa Fe (Litoral Norte de la Habana y Punta del Este (SW de Cuba. En el contenido estomacal de la ascidia se identificaron 59 especies de microalgas y cuatro tintínidos. El tamaño de las células varió entre 75 y 165 µm de largo y de 2 a 105 µm de ancho. No se encontraron diferencias significativas en la diversidad de especies de microalgas en la columna de agua de las dos localidades. Las diatomeas tuvieron la mayor cantidad de especies y el mayor número de individuos, tanto en los estómagos como en la columna de agua en ambas localidades. La biomasa de dinoflagelados en Santa Fe fue mayor en agua y estómagos. En Punta del Este el aporte de cada grupo al contenido estomacal es similar al encontrado en la columna de agua. Esta especie filtra de forma constante e irregular durante las 24 horas del día, independientemente de la disponibilidad de alimento.Diet of the ascidian Ecteinascidia turbinata (Ascidiacea: Perophoridae in two mangrove areas of Cuba. Stomach contents of 88 zooids of Ecteinascidia turbinata Herdman 1880 and the qualitative and quantitative composition of phytoplankton in the water column were studied in Santa Fe (North Coast of Havana and Punta del Este (SW of Cuba. We identified 59 microalgal species and four tintinnids in the stomachs. Cell size was 75-165 µm in length and 2-105 µm in width. There were not significant differences in microalgal diversity in the water column in the two locations. In both locations, the diatoms had the largest number of species and individuals in stomachs and water. In Santa Fe, dinoflagellate biomass was larger in water and stomach contents, while in Punta del Este the contribution of each group to the stomach content was similar to that of the water column. This species filters in a constant and

The developing dorsal ganglion of the salp Thalia democratica, and the nature of the ancestral chordate brain

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C.Lacalli, T.

1998-01-01

The development of the dorsal ganglion of the salp, Thalia democratica, is described from electron microscope reconstructions up to the stage of central neuropile formation. The central nervous system (CNS) rudiment is initially tubular with an open central canal. Early developmental events include: (i) the formation of a thick dorsal mantle of neuroblasts from which paired dorsal paraxial neuropiles arise; (ii) the differentiation of clusters of primary motor neurons along the ventral margin of the mantle; and (iii) the development from the latter of a series of peripheral nerves. The dorsal paraxial neuropiles ultimately connect to the large central neuropile, which develops later. Direct contact between neuroblasts and muscle appears to be involved in the development of some anterior nerves. The caudal nerves responsible for innervating more distant targets in the posterior part of the body develop without such contacts, which suggests that a different patterning mechanism may be employed in this part of the neuromuscular system. The results are compared with patterns of brain organization in other chordates. Because the salp CNS is symmetrical and generally less reduced than that of ascidian larvae, it is more easily compared with the CNS of amphioxus and vertebrates. The dorsal paraxial centres in the salp resemble the dorsolateral tectal centres in amphioxus in both position and organization; the central neuropile in salps likewise resembles the translumenal system in amphioxus. The neurons themselves are similar in that many of their neurites appear to be derived from the apical surface instead of the basal surface of the cell. Such neurons, with extensively developed apical neurites, may represent a new cell type that evolved in the earliest chordates in conjunction with the formation of translumenal or intralumenal integrative centres. In comparing the salp ganglion with vertebrates, we suggest that the main core of the ganglion is most like the mes

Proximate composition of marine invertebrates from tropical coastal waters, with emphasis on the relationship between nitrogen and protein contents

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Graciela S Diniz

2014-05-01

Full Text Available The chemical profiles of Desmapsamma anchorata, Hymeniacidon heliophila (Porifera, Bunodosoma caissarum, Renilla muelleri (Cnidaria, Aplysia brasiliana, Eledone massyae, Isognomon bicolor (Mollusca, Echinaster brasiliensis, Echinometra lucunter, Holothuria grisea, Lytechinus variegatus (Echinodermata, and Phallusia nigra (Chordata were determined. Hydrosoluble protein was the most abundant class of substances for all species, except for the ascidian Phallusia nigra, in which the carbohydrate content was higher. The percentages of hydrosoluble protein (dry weight, dw varied widely among the invertebrates, ranging from 5.88% (R. muelleri to 47.6% (Eledone massyae of the dw .The carbohydrate content fluctuated from 1.3% (R. muelleri to 18.4% (Aplysia brasiliana of the dw. For most of the species, lipid was the second most abundant class of substances, varying from 2.8% (R. muelleri to 25.3% (Echinaster brasiliensis of the dw. Wide variations were also found for the invertebrates nitrogen content, with the lowest value recorded in the cnidarian R. muelleri (2.02% of the dw and the highest in the molluscan E. massyae (12.7% of the dw. The phosphorus content of the dw varyed from 0.24% (R. muelleri to 1.16% (E. massyae. The amino acid composition varied largely among the species, but for most of the species glycine, arginine, glutamic acid, and aspartic acid were the most abundant amino acids, with histidine and tyrosine among the less abundant amino acids. The actual content of total protein in the samples was calculated by the sum of amino acid residues, establishing dw values that fluctuated from 11.1% (R. muelleri to 66.7% (E. massyae. The proteinaceous nitrogen content was high in all species, with an average value of 97.3% of the total nitrogen. From data of total amino acid residues and total nitrogen, specific nitrogen-to-protein conversion factors were calculated for each species. The nitrogen-to-protein conversion factors ranged from 5.10 to

Reproductive protein evolution in two cryptic species of marine chordate

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2011-01-01

Background Reproductive character displacement (RCD) is a common and taxonomically widespread pattern. In marine broadcast spawning organisms, behavioral and mechanical isolation are absent and prezygotic barriers between species often operate only during the fertilization process. Such barriers are usually a consequence of differences in the way in which sperm and egg proteins interact, so RCD can be manifest as faster evolution of these proteins between species in sympatry than allopatry. Rapid evolution of these proteins often appears to be a consequence of positive (directional) selection. Here, we identify a set of candidate gamete recognition proteins (GRPs) in the ascidian Ciona intestinalis and showed that these GRPs evolve more rapidly than control proteins (those not involved in gamete recognition). Choosing a subset of these gamete recognition proteins that show evidence of positive selection (CIPRO37.40.1, CIPRO60.5.1, CIPRO100.7.1), we then directly test the RCD hypothesis by comparing divergence (omega) and polymorphism (McDonald-Kreitman, Tajima's D, Fu and Li's D and F, Fay and Wu's H) statistics in sympatric and allopatric populations of two distinct forms of C. intestinalis (Types A and B) between which there are strong post-zygotic barriers. Results Candidate gamete recognition proteins from two lineages of C. intestinalis (Type A and B) are evolving more rapidly than control proteins, consistent with patterns seen in insects and mammals. However, ω (dN/dS) is not significantly different between the sympatric and allopatric populations, and none of the polymorphism statistics show significant differences between sympatric and allopatric populations. Conclusions Enhanced prezygotic isolation in sympatry has become a well-known feature of gamete recognition proteins in marine broadcast spawners. But in most cases the evolutionary process or processes responsible for this pattern have not been identified. Although gamete recognition proteins in C

Reproductive protein evolution in two cryptic species of marine chordate

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Harrison Richard G

2011-01-01

Full Text Available Abstract Background Reproductive character displacement (RCD is a common and taxonomically widespread pattern. In marine broadcast spawning organisms, behavioral and mechanical isolation are absent and prezygotic barriers between species often operate only during the fertilization process. Such barriers are usually a consequence of differences in the way in which sperm and egg proteins interact, so RCD can be manifest as faster evolution of these proteins between species in sympatry than allopatry. Rapid evolution of these proteins often appears to be a consequence of positive (directional selection. Here, we identify a set of candidate gamete recognition proteins (GRPs in the ascidian Ciona intestinalis and showed that these GRPs evolve more rapidly than control proteins (those not involved in gamete recognition. Choosing a subset of these gamete recognition proteins that show evidence of positive selection (CIPRO37.40.1, CIPRO60.5.1, CIPRO100.7.1, we then directly test the RCD hypothesis by comparing divergence (omega and polymorphism (McDonald-Kreitman, Tajima's D, Fu and Li's D and F, Fay and Wu's H statistics in sympatric and allopatric populations of two distinct forms of C. intestinalis (Types A and B between which there are strong post-zygotic barriers. Results Candidate gamete recognition proteins from two lineages of C. intestinalis (Type A and B are evolving more rapidly than control proteins, consistent with patterns seen in insects and mammals. However, ω (dN/dS is not significantly different between the sympatric and allopatric populations, and none of the polymorphism statistics show significant differences between sympatric and allopatric populations. Conclusions Enhanced prezygotic isolation in sympatry has become a well-known feature of gamete recognition proteins in marine broadcast spawners. But in most cases the evolutionary process or processes responsible for this pattern have not been identified. Although gamete

The fester locus in Botryllus schlosseri experiences selection

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Nydam Marie L

2012-12-01

Full Text Available Abstract Background Allorecognition, the ability of an organism to distinguish self from non-self, occurs throughout the entire tree of life. Despite the prevalence and importance of allorecognition systems, the genetic basis of allorecognition has rarely been characterized outside the well-known MHC (Major Histocompatibility Complex in vertebrates and SI (Self-Incompatibility in plants. Where loci have been identified, their evolutionary history is an open question. We have previously identified the genes involved in self/non-self recognition in the colonial ascidian Botryllus schlosseri, and we can now begin to investigate their evolution. In B. schlosseri, colonies sharing 1 or more alleles of a gene called FuHC (Fusion Histocompatibility will fuse. Protein products of a locus called fester, located ~300 kb from FuHC, have been shown to play multiple roles in the histocompatibility reaction, as activating and/or inhibitory receptors. We test whether the proteins encoded by this locus are evolving neutrally or are experiencing balancing, directional, or purifying selection. Results Nearly all of the variation in the fester locus resides within populations. The 13 housekeeping genes (12 nuclear genes and mitochondrial cytochrome oxidase I have substantially more structure among populations within groups and among groups than fester. All polymorphism statistics (Tajima's D, Fu and Li's D* and F* are significantly negative for the East Coast A-type alleles, and Fu and Li's F* statistic is significantly negative for the West Coast A-type alleles. These results are likely due to selection rather than demography, given that 10 of the housekeeping loci have no populations with significant values for any of the polymorphism statistics. The majority of codons in the fester proteins have ω values 95% posterior probability of ω values > 1. Conclusion Fester proteins are evolving non-neutrally. The polymorphism statistics are consistent with either

Isolation and genome sequencing of four Arctic marine Psychrobacter strains exhibiting multicopper oxidase activity.

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Moghadam, Morteza Shojaei; Albersmeier, Andreas; Winkler, Anika; Cimmino, Lorenzo; Rise, Kjersti; Hohmann-Marriott, Martin Frank; Kalinowski, Jörn; Rückert, Christian; Wentzel, Alexander; Lale, Rahmi

2016-02-16

Marine cold-temperature environments are an invaluable source of psychrophilic microbial life for new biodiscoveries. An Arctic marine bacterial strain collection was established consisting of 1448 individual isolates originating from biota, water and sediment samples taken at a various depth in the Barents Sea, North of mainland Norway, with an all year round seawater temperature of 4 °C. The entire collection was subjected to high-throughput screening for detection of extracellular laccase activity with guaiacol as a substrate. In total, 13 laccase-positive isolates were identified, all belonging to the Psychrobacter genus. From the most diverse four strains, based on 16S rRNA gene sequence analysis, all originating from the same Botryllus sp. colonial ascidian tunicate sample, genomic DNA was isolated and genome sequenced using a combined approach of whole genome shotgun and 8 kb mate-pair library sequencing on an Illumina MiSeq platform. The genomes were assembled and revealed genome sizes between 3.29 and 3.52 Mbp with an average G + C content of around 42%, with one to seven plasmids present in the four strains. Bioinformatics based genome mining was performed to describe the metabolic potential of these four strains and to identify gene candidates potentially responsible for the observed laccase-positive phenotype. Up to two different laccase-like multicopper oxidase (LMCO) encoding gene candidates were identified in each of the four strains. Heterologous expression of P11F6-LMCO and P11G5-LMCO2 in Escherichia coli BL21 (DE3) resulted in recombinant proteins exhibiting 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and guaiacol oxidizing activity. Thirteen Psychrobacter species with laccase-positive phenotype were isolated from a collection of Arctic marine bacteria. Four of the isolates were genome sequenced. The overall genome features were similar to other publicly available Psychrobacter genome sequences except for P11G5 harboring seven

Evolution of the interaction between Runx2 and VDR, two transcription factors involved in osteoblastogenesis

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Barriga Elias H

2010-03-01

, using pull-down experiments between recombinant proteins, we show that the VDR homologue from teleosts, but not from ascidians, is able to directly interact with the mammalian Runx2 homologue. Conclusions We propose an evolutionary scenario for the assembly of the molecular machinery involving Runx2 and VDR in vertebrates. In the last common ancestor of actinopterygians and sacropterygians, the three Runx paralogues possessed the potential to physically and functionally interact with the VDR protein. Therefore, 1α,25-dihydroxyvitamin D3 might have been able to modulate the transcriptional activity of Runx1, Runx2 or Runx3 in the tissues expressing VDR. After the split from amphibians, in the lineage leading to amniotes, Runx2 and VDR became robustly co-expressed in developing skeletal elements, and their regulatory interaction was incorporated in the genetic program involved in the specification and differentiation of osteoblasts.

Phylogeny of the Aplousobranchia (Tunicata: Ascidiacea Filogenia de Aplousobranchia (Tunicata: Ascidiacea

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Tatiane R. Moreno

2008-06-01

Full Text Available The phylogenetic relationships of genera and families of Aplousobranchia Lahille (Tunicata, Ascidiacea is reconstructed based on morphological characters - the first comprehensive morphology-based phylogenetic analysis for the Aplousobranchia. Monophyly of Aplousobranchia and its families were tested with samples of 14 families. The final character matrix comprised 47 characters and 41 genera as terminal taxa. Nine equally most parsimonious trees (length 161, CI = 0.5031, RI = 0.7922 were found. Characters describing replication, colony system formation, and branchial walls were the more important in phylogenetic reconstruction. These characters were more useful than others more traditionally used in ascidian taxonomy, such as: body division, position of the heart, gonads and epicardium. Characters not frequently used in phylogenetic analysis, such as body wall muscles, muscles associated with transversal blood vessels and arrangement of the larval papillae, also have phylogenetic information. Results supported monophyly of the Aplousobranchia sensu Lahille, 1887 including only Polycitoridae, Polyclinidae, and Didemnidae. On the other hand, Aplousobranchia including also Cionidae and Diazonidae is not monophyletic since Perophora and Ecteinascidia were included as ingroups in the cladogram, Ciona (now closer to Ascidia was no longer included in Aplousobranchia and the position of Rhopalaea and Diazona is not resolved. We propose a revised classification based on this phylogenetic analysis, in which Aplousobranchia, with three new families and an indeterminate taxon, now has 15 families.O relacionamento filogenéticos de gêneros e famílias de de Aplousobranchia Lahille (Tunicata, Ascidiacea foi reconstruída com base em caracteres morfológicos - esta constitui a primeira análise filogenética morfológica abrangente para Aplousobranchia. A monofilia de Aplousobranchia e suas famílias foi testada com espécies de 14 famílias. A matriz final

Distribuição geográfica da fauna e flora da Baía de Guanabara Geographic distribution of the flora and the fauna of the Guanabara Bay

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Lejeune P. H. de Oliveira

1947-09-01

(Latreille and the sparingly the big oyster Ostrea rhizophorae Guild. Lower is the region of barnacles Balanus amphitrite var. communis Darwin and var. niveus Darwin; Balanus tintinnabulum var. tintinnabulum (L. doesn't grow in this brackish water; lower is the region of Pelecipoda with prepollency of Venus and Cytherea shell-fishes and the Panopeus mud crab; there are the sea lettuce Ulva and the Gastreropod Cerithium. The Paguridae Clibanarius which lives in the empty shells of Gasteropod molluscs, and the sessile ascidians Tethium plicatum (Lesuer appears in some seasons. In the bottom there is a black argillous mud where the «one landed shrimps» Alpheus sp. is hidden. OLIGOHALINE WATER REGIME — The salinity is lower than 10/1.000. average 8/1.000. There are no barnacles and no sea-beetles Isopods of genus Lygia; on the hay of the shore there are several graminea. This brackish water pervades by mouthes of rivers and penetrates until about 3 kilometers river above. While there is some salt dissolved in water, there are some mud crabs of the genus Uca, Sesarma, Metasesarma and Chasmagnatus. The presence of floating green plants coming from the rivers in the waters of a region indicated the oligohaline waters, with low salt content because when the average of NaCl increases above 8/1.000 these plants die and become rusty colored.