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Sample records for ascidian halocynthia roretzi

  1. Complete DNA sequence of the mitochondrial genome of the ascidian Halocynthia roretzi (Chordata, Urochordata).

    PubMed Central

    Yokobori, S i; Ueda, T; Feldmaier-Fuchs, G; Pääbo, S; Ueshima, R; Kondow, A; Nishikawa, K; Watanabe, K

    1999-01-01

    The complete nucleotide sequence of the 14,771-bp-long mitochondrial (mt) DNA of a urochordate (Chordata)-the ascidian Halocynthia roretzi-was determined. All the Halocynthia mt-genes were found to be located on a single strand, which is rich in T and G rather than in A and C. Like nematode and Mytilus edulis mtDNAs, that of Halocynthia encodes no ATP synthetase subunit 8 gene. However, it does encode an additional tRNA gene for glycine (anticodon TCT) that enables Halocynthia mitochondria to use AGA and AGG codons for glycine. The mtDNA carries an unusual tRNA(Met) gene with a TAT anticodon instead of the usual tRNA(Met)(CAT) gene. As in other metazoan mtDNAs, there is not any long noncoding region. The gene order of Halocynthia mtDNA is completely different from that of vertebrate mtDNAs except for tRNA(His)-tRNA(Ser)(GCU), suggesting that evolutionary change in the mt-gene structure is much accelerated in the urochordate line compared with that in vertebrates. The amino acid sequences of Halocynthia mt-proteins deduced from their gene sequences are quite different from those in other metazoans, indicating that the substitution rate in Halocynthia mt-protein genes is also accelerated. PMID:10581290

  2. Complete DNA sequence of the mitochondrial genome of the ascidian Halocynthia roretzi (Chordata, Urochordata).

    PubMed

    Yokobori, S i; Ueda, T; Feldmaier-Fuchs, G; Pääbo, S; Ueshima, R; Kondow, A; Nishikawa, K; Watanabe, K

    1999-12-01

    The complete nucleotide sequence of the 14,771-bp-long mitochondrial (mt) DNA of a urochordate (Chordata)-the ascidian Halocynthia roretzi-was determined. All the Halocynthia mt-genes were found to be located on a single strand, which is rich in T and G rather than in A and C. Like nematode and Mytilus edulis mtDNAs, that of Halocynthia encodes no ATP synthetase subunit 8 gene. However, it does encode an additional tRNA gene for glycine (anticodon TCT) that enables Halocynthia mitochondria to use AGA and AGG codons for glycine. The mtDNA carries an unusual tRNA(Met) gene with a TAT anticodon instead of the usual tRNA(Met)(CAT) gene. As in other metazoan mtDNAs, there is not any long noncoding region. The gene order of Halocynthia mtDNA is completely different from that of vertebrate mtDNAs except for tRNA(His)-tRNA(Ser)(GCU), suggesting that evolutionary change in the mt-gene structure is much accelerated in the urochordate line compared with that in vertebrates. The amino acid sequences of Halocynthia mt-proteins deduced from their gene sequences are quite different from those in other metazoans, indicating that the substitution rate in Halocynthia mt-protein genes is also accelerated.

  3. The development of three identified motor neurons in the larva of an ascidian, Halocynthia roretzi.

    PubMed

    Okada, Toshiaki; Katsuyama, You; Ono, Fumihito; Okamura, Yasushi

    2002-04-15

    The generation of distinct classes of motor neurons underlies the development of complex motile behavior in all animals and is well characterized in chordates. Recent molecular studies indicate that the ascidian larval central nervous system (CNS) exhibits anteroposterior regionalization similar to that seen in the vertebrate CNS. To extend the understanding about the diversity of motor neurons in the ascidian larva, we have identified the number, position, and projection of individual motor neurons in Halocynthia roretzi, using a green fluorescent protein under the control of a neuron-specific promoter. Three pairs of motor neurons, each with a distinct shape and innervation pattern, were identified along the anteroposterior axis of the neural tube: the anterior and posterior pairs extend their axons toward dorsal muscle cells, whereas the middle pair project their axons toward ventral muscle. Overexpression of a dominant-negative form of a potassium channel in these cells resulted in paralysis on the injected side, thus these cells must constitute the major population of motor neurons responsible for swimming behavior. Lim class homeobox genes have been known as candidate genes that determine subtypes of motor neurons. Therefore, the expression pattern of Hrlim, which is a Lim class homeobox gene, was examined in the motor neuron precursors. All three motor neurons expressed Hrlim at the tailbud stage, although each down-regulated Hrlim at a different time. Misexpression of Hrlim in the epidermal lineage led to ectopic expression of TuNa2, a putative voltage-gated channel gene normally expressed predominantly in the three pairs of motor neurons. Hrlim may control membrane excitability of motor neurons by regulating ion channel gene expression.

  4. Isolation of an early neural maker gene abundantly expressed in the nervous system of the ascidian, Halocynthia roretzi.

    PubMed

    Yagi, K; Makabe, K W

    2001-01-01

    Ascidian tadpole larvae possess a primitive nervous system, which is a prospective prototype of the chordate nervous system. It is composed of relatively few cells but sufficient for complex larval behavior. Here we report on HrETR-1, a gene zygotically expressed in a large proportion of the developing neural cells of the ascidian, Halocynthia roretzi. HrETR-1 is an early neural marker which can be used for analyzing neural differentiation. HrETR-1 expression intensified in most neural cells of genes isolated to date, in both central and peripheral nervous systems including palps as early as the 110-cell stage. Using this gene as a probe, we characterized neural cells in the nervous system as well as confirming their origins. Also, we recognized three types of peripheral epidermal neurons which presumably correlate to the larval neurons previously reported for another ascidian. Among these, five bilateral neurons located in the anterior region of the trunk appeared to be derived from a8.26 blastomeres.

  5. Tunic morphology and viral surveillance in diseased Korean ascidians: Soft tunic syndrome in the edible ascidian, Halocynthia roretzi (Drasche), in aquaculture.

    PubMed

    Kitamura, S-I; Ohtake, S-I; Song, J-Y; Jung, S-J; Oh, M-J; Choi, B-D; Azumi, K; Hirose, E

    2010-02-01

    'Soft tunic syndrome' causes mass mortality in the edible ascidian Halocynthia roretzi in Korean and Japanese aquaculture. In histopathological comparison, there were no specific differences between diseased specimens from Korea and Japan, indicating that soft tunic syndrome occurring in Korea and Japan is the same disease. No bacterial or protozoan cells were microscopically detected in either healthy or diseased tunics suggesting they are not the direct causes of soft tunic syndrome. Attempts were made to isolate virus from affected ascidians taking into account temperature conditions in which soft tunic syndrome is most prevalent in the field. However, no viruses were isolated from diseased or non-diseased specimens using chinook salmon embryo (CHSE-214), flounder fin (FFN) or epithelioma papillosum cyprini (EPC) cell lines.

  6. Trypsin-like enzyme from eggs of the ascidian (protochordate), Halocynthia roretzi. Purification, properties, and physiological role.

    PubMed

    Sawada, H; Kawahigashi, M; Yokosawa, H; Ishii, S

    1985-12-15

    A trypsin-like enzyme has been purified to apparent homogeneity from eggs of the ascidian, Halocynthia roretzi, by a procedure including column chromatography on diethylaminoethyl-cellulose, phenyl-Sepharose, and soybean trypsin inhibitor-immobilized Sepharose 4B. The molecular weight of the enzyme was estimated to be 31,000 and 33,000 by gel electrophoresis in sodium dodecyl sulfate under the reducing and the nonreducing conditions, respectively. The isoelectric point of the enzyme was 4.8. The pH optimum of the activity was 8.4. The enzyme was stable between pH 6 and 9 in the presence of 0.005% Brij 35 as a stabilizer. Substrate specificity of the purified enzyme was broad toward various peptidyl-arginine (or -lysine) 4-methylcoumaryl-7-amides and was similar to that of a trypsin-like enzyme found in the fertilization product. The purified enzyme was inhibited by diisopropyl fluorophosphate and a variety of trypsin inhibitors including leupeptin, but not, or scarcely, inhibited by p-chloromercuribenzoic acid, pepstatin, chymostatin, bestatin, elastatinal, and tosyl-phenylalanyl-chloromethane. The rankings in the potencies of leupeptin and its six analogs as the inhibitors of the purified enzyme were well correlated with those found in their inhibitory effects on the expansion of perivitelline space. Thus, the trypsin-like enzyme possibly present in the fertilization product participates in the expansion of perivitelline space of the egg during fertilization of the ascidian.

  7. Morphological characterization of the tunic in the edible ascidian, Halocynthia roretzi (Drasche), with remarks on 'soft tunic syndrome' in aquaculture.

    PubMed

    Hirose, E; Ohtake, S-I; Azumi, K

    2009-05-01

    'Soft tunic syndrome' is a serious problem in the aquaculture of the edible ascidian, Halocynthia roretzi (Drasche), and often leads to mass mortality. Here, we describe the tunic morphology of intact and diseased ascidians to reveal structural differences between them. Morphologically, diseased tunics are not very different from intact tunics, although the former are thinner and softer than the latter. While several types of cells are distributed in the tunic, the cell types and their cytomorphologies were almost identical in both groups. As bacterial/protozoan cells were not found in either intact or diseased tunics, they are not the direct cause of soft tunic syndrome. The most remarkable difference was in the bundles of tunic fibres that compose the tunic matrix; in intact tunics, the thick bundles interlace to form a firm matrix, whereas in soft tunics, the tunic fibres do not form thick bundles. Furthermore, areas of low fibre density were found in diseased tunics. Therefore, soft tunic syndrome probably causes inhibition of bundle formation and degradation of tunic bundles, creating areas of low fibre density, although the causes remain unknown.

  8. Isolation of cDNA clones for mRNAs transcribed zygotically during cleavage in the ascidian, Halocynthia roretzi.

    PubMed

    Miya, Takahito; Nishida, Hiroki

    2002-02-01

    The ascidian larva consists of a relatively small number of different cell types, and the cell lineages during embryogenesis have been well described. The clonal restriction of developmental fate takes place considerably early in development. The fates of most of the blastomeres become tissue-restricted by the 110-cell stage, just before the onset of gastrulation. To elucidate the molecular basis of the early events of fate determination in the ascidian Halocynthia roretzi, we isolated the genes for which zygotic expression is initiated during the early cleavage stages. Here we report 18 genes isolated by subtractive hybridization screening between 110-cell embryos and fertilized eggs. The expression of most (13) of the genes was initiated at the 32-cell stage. The genes were subdivided into three groups according to their spatial expression patterns. The first group included clones expressed throughout almost the entire embryo. The second and third groups represented clones expressed mainly in the animal hemisphere and in a subset of vegetal blastomeres, respectively. One of the genes, HrHesl1, encoded a polypeptide containing the bHLH domain that is similar to those of the Hairy/Enhancer of split/Deadpan family of transcriptional repressors. HrHesl1 was expressed exclusively in epidermal precursor cells during cleavage. Another gene named HrWnt-5 beta was expressed in muscle precursors.

  9. Follicle cell trypsin-like protease HrOvochymase: Its cDNA cloning, localization, and involvement in the late stage of oogenesis in the ascidian Halocynthia roretzi.

    PubMed

    Mino, Masako; Sawada, Hitoshi

    2016-04-01

    We previously reported that the sperm trypsin-like protease HrAcrosin and its precursor HrProacrosin participate in fertilization of the ascidian Halocynthia roretzi. The HrProacrosin gene is annotated in the H. roretzi genome database as Harore.CG.MTP2014.S89.g15383; our previously reported sequence of HrProacrosin gene appeared to include four nucleotides inserted near the 3'-end of HrProacrosin, resulting in a frame-shift mutation and a premature termination codon. The gene architecture of HrProacrosin and Harore.CG.MTP2014.S89.g15383 resembles that of Xenopus laevis ovochymase-1/OVCH1 and ovochymase-2/OVCH2, which encode egg extracellular polyproteases. Considering these new observations, we evaluated the cDNA cloning, expression, localization, and function of Harore.CG.MTP2014.S89.g15383, herein designated as HrOvochymase/HrOVCH. We found that HrOVCH cDNA consists of a single open reading frame of 1,575 amino acids, containing a signal peptide, three trypsin-like protease domains, and six CUB domains. HrOVCH was transcribed by the testis and ovary, but the majority of protein exists in ovarian follicle cells surrounding eggs. An anti-HrOVCH antibody inhibited elevation of the vitelline coat at a late stage of oogenesis, during the period when self-sterility is acquired. As trypsin inhibitors are reported to block the acquisition of self-sterility during oogenesis, whereas trypsin induces the acquisition of self-sterility and elevation of the vitelline coat in defolliculated ovarian eggs, we propose that HrOVCH may play a role in the acquisition of self-sterility by late-stage H. roretzi oocytes.

  10. Purification and characterization of a 39,000-Da serine proteinase from the hemolymph of a solitary ascidian, Halocynthia roretzi.

    PubMed

    Shishikura, F; Abe, T; Ohtake, S; Tanaka, K

    1997-09-01

    A new endogenous serine proteinase from the cell-free hemolymph of a solitary ascidian, Halocythia roretzi, was purified by a combination of ammonium sulfate fractionation, hydrophobic interaction chromatography on TSKgel Toyopearl HW 65 F, ion exchange chromatography on TSKgel DEAE-Toyopearl 650 M, affinity chromatography on Arginine-Sepharose 4B, gel filtration on TSKgel Toyopearl HW 65F and hydroxyapatite chromatography on Bio-Gel HT. The serine proteinase is a single polypeptide chain whose molecular weight and isoelectric point are 39 kDa and about 7.6 pI, respectively. The most susceptible substrate was Boc-Leu-Gly-Arg-4-methyl-coumaryl-7-amide (MCA), and activity was optimal at pH 8. The enzyme was relatively stable at high temperatures; about 50% activity was retained even at 60 degrees C for 30 min in 50 mM Tris-HCl, pH 8.0, containing 0.5 M NaCl, and 0.05% Brij-35. The enzyme was characterized by the inhibitory effects of synthetic or natural inhibitors, substrate specificity toward 26 peptidyl-MCAs, proteinase activity toward natural proteins and complex formation with a serine proteinase inhibitor (58 kDa) previously found in H. roretzi hemolymph, indicating that the enzyme was a member of serine proteinases and strongly inhibited by the 58 kDa serine proteinase inhibitor as well as human antithrombin III. We also demonstrated the clotting enzyme activity of the purified serine proteinase toward bovine fibrinogen and Limulus coagulogen, a fibrinogen-like clottable protein of horseshoe crabs.

  11. Transcription regulatory mechanism of Pitx in the papilla-forming region in the ascidian, Halocynthia roretzi, implies conserved involvement of Otx as the upstream gene in the adhesive organ development of chordates.

    PubMed

    Yoshida, Keita; Ueno, Motoko; Niwano, Tomoko; Saiga, Hidetoshi

    2012-08-01

    Pitx genes play important roles in a variety of developmental processes in vertebrates. In an ascidian species, Halocynthia roretzi, Hr-Pitx, the only Pitx gene of this species, has been reported to be expressed in the left epidermis at the tailbud stage. In the present study, first, we have shown that Hr-Pitx is also expressed in the papilla-forming region at the neurula to tailbud stages, and then we addressed transcription regulatory mechanisms for the expression of Hr-Pitx in the papilla-forming region. We have identified the genomic region ranging from 850 to 1211 bp upstream from the translation start site of the Hr-Pitx gene as an enhancer region that drives the transcription of Hr-Pitx in the papilla-forming region. Within the enhancer region, putative transcriptional factor binding sites for Otx as well as Fox were shown to be required for its activity. Finally, we carried out knocking down experiments of Hr-Otx function using an antisense morpholino oligonucleotide, in which the knocking down of Hr-Otx function resulted in reduction of the enhancer activity and loss of the expression of Hr-Pitx in the papilla-forming region. In Xenopus laevis, it has been reported that Pitx genes are expressed downstream of Otx function during development of the cement gland, an adhesive organ of its larva. Taken together, it is suggested that the expression regulatory mechanism of Pitx, involving Otx as the upstream gene, in the developing adhesive organ is conserved between ascidians and vertebrates.

  12. Characterization of a Novel Rhamnose-containing Acidic Glycosphingolipid from the Ascidian Halocynthia aurantium.

    PubMed

    Kojima, Hisao; Shinohara, Ryota; Itonori, Saki; Ito, Masahiro

    2017-03-01

    Halocynthia aurantium, an edible ascidian species belonging to Urochordata, was subjected to structural characterization of acidic glycosphingolipids to investigate these molecules in ascidians: sulfatide from Ciona intestinalis and the glucuronic acid-containing acidic glycosphingolipid from H. roretzi. Acidic glycosphingolipids containing three or five sugars were isolated from soft parts of the ascidian H. aurantium by chloroform-methanol extraction, mild-alkaline hydrolysis, precipitation with cold acetone, and subsequent column chromatography using a DEAE-Sephadex A-25 column, a Florisil column, and an Iatrobead column. The structures of these glycosphingolipids were determined by methylation studies, sugar analysis, fatty acid analysis, sphingoid analysis, mass spectrometry, and proton nuclear magnetic resonance spectroscopy. A novel glucuronic acid-containing glycosphingolipid having a rhamnose residue was identified as Rhaα1-3GlcNAcβ1-3Galβ1-4(Fucα1-3)GlcAβ1-Cer (UGL-2). This novel structure is particularly unusual given that it contains both a rhamnose residue and a reducing terminal glucuronic acid residue within a single molecule. Rhamnose is a characteristic sugar, which is a component of cell wall pectin in plants and exopolysaccharides in bacteria. Ascidians acquired the cellulose synthase gene via lateral gene transfer, and therefore, it can be speculated that they also acquired the rhamnosyltransferase gene in the same manner. We also detected Galβ1-4(Fucα1-3)GlcAβ1-Cer (UGL-1), which was already identified in another ascidian, H. roretzi.

  13. Effects of sea squirt (Halocynthia roretzi) lipids on white adipose tissue weight and blood glucose in diabetic/obese KK-Ay mice.

    PubMed

    Mikami, Nana; Hosokawa, Masashi; Miyashita, Kazuo

    2010-01-01

    Lipids extracted from Halocynthia roretzi contain n-3 polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid, as well as carotenoids. The aim of the present study was to evaluate the effect of H. roretzi lipids on white adipose tissue (WAT) weight and high blood glucose levels in diabetic/obese KK-Ay mice. H. roretzi lipids were fed to the diabetic/obese KK-Ay mice for 5 weeks. In the mice treated with the H. roretzi lipids compared to control mice, WAT weight was reduced, blood glucose levels and leptin mRNA expression in the epididymal WAT were significantly decreased, serum leptin levels also tended to decrease, and serum adiponectin levels tended to increase. These results demonstrate that H. roretzi lipids have beneficial health effects on diabetic/obese KK-Ay mice.

  14. Neurula rotation determines left-right asymmetry in ascidian tadpole larvae.

    PubMed

    Nishide, Kazuhiko; Mugitani, Michio; Kumano, Gaku; Nishida, Hiroki

    2012-04-01

    Tadpole larvae of the ascidian Halocynthia roretzi show morphological left-right asymmetry. The tail invariably bends towards the left side within the vitelline membrane. The structure of the larval brain is remarkably asymmetric. nodal, a conserved gene that shows left-sided expression, is also expressed on the left side in H. roretzi but in the epidermis unlike in vertebrates. We show that nodal signaling at the late neurula stage is required for stereotypic morphological left-right asymmetry at later stages. We uncover a novel mechanism to break embryonic symmetry, in which rotation of whole embryos provides the initial cue for left-sided expression of nodal. Two hours prior to the onset of nodal expression, the neurula embryo rotates along the anterior-posterior axis in a counterclockwise direction when seen in posterior view, and then this rotation stops when the left side of the embryo is oriented downwards. It is likely that epidermis monocilia, which appear at the neurula rotation stage, generate the driving force for the rotation. When the embryo lies on the left side, protrusion of the neural fold physically prevents it from rotating further. Experiments in which neurula rotation is perturbed by various means, including centrifugation and sandwiching between glass, indicate that contact of the left epidermis with the vitelline membrane as a consequence of neurula rotation promotes nodal expression in the left epidermis. We suggest that chemical, and not mechanical, signals from the vitelline membrane promote nodal expression. Neurula rotation is also conserved in other ascidian species.

  15. Genetic Distances in Three Ascidian Species determined by PCR Technique

    PubMed Central

    Yoon, Jong-Man

    2016-01-01

    ABSTRACT Seven oligonucleotides primers were shown to generate the shared loci, specific loci, unique shared loci to each species and shared loci by the three species which could be obviously scored. In the present study, 7 oligonucleotides primers produced 401 total loci in the Styela clava (SC) species, 390 in the Halocynthia roretzi (HR) and 434 in the Styela plicata (SP), respectively. Seven oligonucleotides primers generated 275 specific loci in the SC, 341 in the HR and 364 in the SP species, respectively. The oligonucleotides primer BION-23 generated 28 unique loci to each species in the SP species. Especially, the oligonucleotides primer BION-25 produced 7 unique loci to each species, which were identifying each species in the SP species. BION-17 distinguished 21 shared loci by the three ascidian species, major and/or minor fragments of sizes, which were identical in almost all of the samples. Based on the average bandsharing values of all samples, the similarity matrix ranged from 0.519 to 0.774 in the SC species, from 0.261 to 0.683 in the HR species and from 0.346 to 0.730 in the SP species. As regards average bandsharing value (BS) results, individuals from SC species (0.661±0.081) exhibited higher bandsharing values than did individuals from HR species (0.555±0.074) (P<0.05). The dendrogram obtained by the seven oligonucleotides primers indicates three genetic groups. In three ascidian species, the shortest genetic distance (0.071) exhibiting significant molecular difference was also between individual no. 20 and no. 21 within the SP species. PMID:28144642

  16. Transcript Mapping and Genome Annotation of Ascidian mtDNA Using EST Data

    PubMed Central

    Gissi, Carmela; Pesole, Graziano

    2003-01-01

    Mitochondrial transcripts of two ascidian species were reconstructed through sequence assembly of publicly available ESTs resembling mitochondrial DNA sequences (mt-ESTs). This strategy allowed us to analyze processing and mapping of the mitochondrial transcripts and to investigate the gene organization of a previously uncharacterized mitochondrial genome (mtDNA). This new strategy would greatly facilitate the sequencing and annotation of mtDNAs. In Ciona intestinalis, the assembled mt-ESTs covered 22 mitochondrial genes (∼12,000 bp) and provided the partial sequence of the mtDNA and the prediction of its gene organization. Such sequences were confirmed by amplification and sequencing of the entire Ciona mtDNA. For Halocynthia roretzi, for which the mtDNA sequence was already available, the inferred mt transcripts allowed better definition of gene boundaries (16S rRNA, ND1, ATP6, and tRNA-Ser genes) and the identification of a new gene (an additional Phe-tRNA). In both species, polycistronic and immature transcripts, creation of stop codons by polyadenylation, tRNA signal processing, and rRNA transcript termination signals were identified, thus suggesting that the main features of mitochondrial transcripts are conserved in Chordata. PMID:12915488

  17. Postplasmic/PEM RNAs: a class of localized maternal mRNAs with multiple roles in cell polarity and development in ascidian embryos.

    PubMed

    Prodon, François; Yamada, Lixy; Shirae-Kurabayashi, Maki; Nakamura, Yoriko; Sasakura, Yasunori

    2007-07-01

    Ascidian is a good model to understand the cellular and molecular mechanisms responsible for mRNA localization with the discovery of a large family of localized maternal mRNAs, called postplasmic/PEM RNAs, which includes more than 40 members in three different ascidian species (Halocynthia roretzi, Ciona intestinalis, and C. savignyi). Among these mRNAs, two types (Type I and Type II) have been identified and show two different localization patterns from fertilization to the eight-cell stage. At the eight-cell stage, both types concentrate to a macromolecular cortical structure called CAB (for Centrosome Attracting Body) in the posterior-vegetal B4.1 blastomeres. The CAB is responsible for unequal cleavages and the partitioning of postplasmic/PEM RNAs at the posterior pole of embryos during cleavage stages. It has also been suggested that the CAB region could contain putative germ granules. In this review, we discuss recent data obtained on the distribution of Type I postplasmic/PEM RNAs from oogenesis to late development, in relation to their localization and translational control. We have first regrouped localization patterns for Type I and Type II into a comparative diagram and included all important definitions in the field. We also have made an exhaustive classification of their embryonic expression profiles (Type I or Type II), and analyzed their functions after knockdown and/or overexpression experiments and the role of the 3'-untranslated region (3'UTR) controlling both their localization and translation. Finally, we propose a speculative model integrating recent data, and we also discuss the relationship between postplasmic/PEM RNAs, posterior specification, and germ cell formation in ascidians.

  18. Identification and localization of the sperm CRISP family protein CiUrabin involved in gamete interaction in the ascidian Ciona intestinalis.

    PubMed

    Yamaguchi, Akira; Saito, Takako; Yamada, Lixy; Taniguchi, Hisaaki; Harada, Yoshito; Sawada, Hitoshi

    2011-07-01

    Ascidians are hermaphrodites, and most release sperm and eggs nearly simultaneously. Many species, including Halocynthia roretzi and Ciona intestinalis, are self-sterile. We previously reported that the interaction between a 12 EGF-like repeat-containing vitelline-coat (VC) protein, HrVC70, and a sperm GPI-anchored CRISP, HrUrabin, in lipid rafts plays a key role in self-/nonself-recognizable gamete interaction in H. roretzi. On the other hand, we recently identified two pairs of polymorphic genes responsible for self-incompatibility in C. intestinalis by positional cloning: The sperm polycystin 1-like receptors s-Themis-A/B and its fibrinogen-like ligand v-Themis-A/B on the VC. However, it is not known if the orthologs of HrVC70 and HrUrabin also participate in gamete interaction in C. intestinalis since they are from different orders. Here, we tested for a C. intestinalis ortholog (CiUrabin) of HrUrabin by searching the genome database and proteomes of sperm lipid rafts. The identified CiUrabin belongs to the CRISP family, with a PR domain and a GPI-anchor-attachment site. CiUrabin appears to be specifically expressed in the testis and localized at the surface of the sperm head, as revealed by Northern blotting and immunocytochemistry, respectively. The specific interaction between CiVC57, a C. intestinalis ortholog of HrVC70, and CiUrabin was confirmed by Far Western analysis, similarly to the interaction between HrVC70 and HrUrabin. The molecular interaction between CiVC57 and CiUrabin may be involved in the primary binding of sperm to the VC prior to the allorecognition process, mediated by v-Themis-A/B and s-Themis-A/B, during fertilization of C. intestinalis.

  19. Neural differentiation in cleavage-arrested ascidian blastomeres induced by a proteolytic enzyme.

    PubMed Central

    Okado, H; Takahashi, K

    1993-01-01

    1. As previously reported, ectodermal a4-2 blastomeres isolated from 8-cell embryos of the ascidian, Halocynthia roretzi or aurantium, and cultured under conditions of cleavage arrest always differentiated into an epidermal phenotype, showing long-lasting Ca(2+)-dependent action potentials and/or tunic on the cell surface. a4-2 blastomeres contacted by a chordamesodermal blastomere, A4-1, differentiated into a neural phenotype, characterized by fast Na(+)-dependent spikes. Differentiation to a similar neural phenotype occurred when isolated a4-2 blastomeres from H. aurantium embryos were treated with > 0.003% subtilisin for 60 min at the 32-cell stage of the control embryo. Comparisons between induction by cell contact and induction by proteolytic enzymes were made and showed them to be similar in several respects. 2. When the serine protease, subtilisin, was used as the neural inducer, neural competence of a4-2 blastomeres, measured as the percentage frequency of the induction of Na+ spikes, increased after the 32-cell stage and decreased during the gastrula stage. The time course of the neural competence was the same as that for contact with the A4-1 blastomere. 3. The neural competence of four different ectodermal blastomeres isolated from the 16-cell embryo was also examined using subtilisin as a neural inducer, and by contact with the A4-1 blastomere from the 8-cell embryo. The competence was higher in anterior blastomeres than in posterior blastomeres for both types of induction. This regional difference in neural competence along the antero-posterior axis paralleled that expected from neural cell lineage during normal development, i.e. blastomeres with more cells of neural lineage among their derivatives showed higher competence. 4. Streptomyces subtilisin inhibitor, SSI (0.1%), a specific protease inhibitor for subtilisin-type serine proteases, significantly suppressed (50%) neural induction of the ectodermal blastomere, a4-2, by contact with the

  20. Ascidian recruitment patterns on an artificial reef in Eilat (Red Sea).

    PubMed

    Shenkar, Noa; Zeldman, Yael; Loya, Yossi

    2008-01-01

    Although ascidians are conspicuous members of the fouling community not much is known regarding their recruitment patterns in coral reefs. A 1-year study was carried out along the Red Sea coast of Israel to examine the effects of season and spatial distribution on ascidian recruitment to artificial marine structures. In general, autumn and spring were characterized by higher coverage with a significantly higher percentage of cover of Didemnum granulatum in autumn and higher numbers of Herdmania momus in spring. These species contributed the most to similarity between treatments consequently setting the pattern for each group (colonial and solitary). Halocynthia spinosa had significantly higher numbers during winter and Phallusia nigra was absent in spring and winter. H. momus showed a preference for horizontal surfaces. P. nigra and Ascidia cannelata showed a preference for floating units. It is concluded that the ascidian recruitment patterns are species-specific and vary between seasons, orientation and position on the substrata and in the water column.

  1. Ascidian depth zonation on sublittoral hard substrates off deer island, New Brunswick, Canada

    NASA Astrophysics Data System (ADS)

    Hatfield, C.; Logan, A.; Thomas, M. L. H.

    1992-02-01

    The upper surfaces of sublittoral hard substrates in the Deer Island region of the Bay of Fundy, New Brunswick, support diverse, depth-zoned epibenthic communities of which ascidians form a minor part. Their population density was quantitatively studied from photo-transects taken between mean low water (MLW) and 30 m depth at four sites off the Deer Island coast and from 30-140 m depth along two photo-transects in Head Harbour Passage. All photo-analyses were aided by collections from transect survey sites, wharf pilings and salmon cage floats, to yield a total of 15 ascidian species encountered. Ascidians were found at all depths at the four shallow sites. Halocynthia pyriformis and Boltenia ovifera are most common at depths of less than 20 m, while Aplidium pallidum, Didemnum albidum and other species exhibit a marked increase in abundance below this depth. Cluster analysis of ascidians shows an association between B. echinata and B. ovifera, which may reflect resource partitioning, and between A. pallidum-D. albidum and Molgula sp.— A. stellatum, the ecological significance of which are as yet unknown. The community in Head Harbour Passage is animal-dominated and in its deeper sections often shows three-dimensional bottom relief from horse mussel shells. D. albidum, the commonest ascidian, shows a close association with Modiolus modiolus, to which it is normally attached, suggesting that mussel beds may minimize the possibility of dislodgement and even confer a feeding advantage on this ascidian.

  2. Metamorphosis in solitary ascidians.

    PubMed

    Karaiskou, Anthi; Swalla, Billie J; Sasakura, Yasunori; Chambon, Jean-Philippe

    2015-01-01

    Embryonic and postembryonic development in ascidians have been studied for over a century, but it is only in the last 10 years that the complex molecular network involved in coordinating postlarval development and metamorphosis has started to emerge. In most ascidians, the transition from the larval to the sessile juvenile/adult stage, or metamorphosis, requires a combination of environmental and endogenous signals and is characterized by coordinated global morphogenetic changes that are initiated by the adhesion of the larvae. Cloney was the first to describe cellular events of ascidians' metamorphosis in 1978 and only recently elements of the molecular regulation of this crucial developmental step have been revealed. This review aims to present a thorough view of this crucial developmental step by combining recent molecular data to the already established cellular events.

  3. Divergent mechanisms regulate conserved cardiopharyngeal development and gene expression in distantly related ascidians

    PubMed Central

    Stolfi, Alberto; Lowe, Elijah K; Racioppi, Claudia; Ristoratore, Filomena; Brown, C Titus; Swalla, Billie J; Christiaen, Lionel

    2014-01-01

    Ascidians present a striking dichotomy between conserved phenotypes and divergent genomes: embryonic cell lineages and gene expression patterns are conserved between distantly related species. Much research has focused on Ciona or Halocynthia spp. but development in other ascidians remains poorly characterized. In this study, we surveyed the multipotent myogenic B7.5 lineage in Molgula spp. Comparisons to the homologous lineage in Ciona revealed identical cell division and fate specification events that result in segregation of larval, cardiac, and pharyngeal muscle progenitors. Moreover, the expression patterns of key regulators are conserved, but cross-species transgenic assays uncovered incompatibility, or ‘unintelligibility’, of orthologous cis-regulatory sequences between Molgula and Ciona. These sequences drive identical expression patterns that are not recapitulated in cross-species assays. We show that this unintelligibility is likely due to changes in both cis- and trans-acting elements, hinting at widespread and frequent turnover of regulatory mechanisms underlying otherwise conserved aspects of ascidian embryogenesis. DOI: http://dx.doi.org/10.7554/eLife.03728.001 PMID:25209999

  4. Deep Sequencing of Mixed Total DNA without Barcodes Allows Efficient Assembly of Highly Plastic Ascidian Mitochondrial Genomes

    PubMed Central

    Rubinstein, Nimrod D.; Feldstein, Tamar; Shenkar, Noa; Botero-Castro, Fidel; Griggio, Francesca; Mastrototaro, Francesco; Delsuc, Frédéric; Douzery, Emmanuel J.P.; Gissi, Carmela; Huchon, Dorothée

    2013-01-01

    Ascidians or sea squirts form a diverse group within chordates, which includes a few thousand members of marine sessile filter-feeding animals. Their mitochondrial genomes are characterized by particularly high evolutionary rates and rampant gene rearrangements. This extreme variability complicates standard polymerase chain reaction (PCR) based techniques for molecular characterization studies, and consequently only a few complete Ascidian mitochondrial genome sequences are available. Using the standard PCR and Sanger sequencing approach, we produced the mitochondrial genome of Ascidiella aspersa only after a great effort. In contrast, we produced five additional mitogenomes (Botrylloides aff. leachii, Halocynthia spinosa, Polycarpa mytiligera, Pyura gangelion, and Rhodosoma turcicum) with a novel strategy, consisting in sequencing the pooled total DNA samples of these five species using one Illumina HiSeq 2000 flow cell lane. Each mitogenome was efficiently assembled in a single contig using de novo transcriptome assembly, as de novo genome assembly generally performed poorly for this task. Each of the new six mitogenomes presents a different and novel gene order, showing that no syntenic block has been conserved at the ordinal level (in Stolidobranchia and in Phlebobranchia). Phylogenetic analyses support the paraphyly of both Ascidiacea and Phlebobranchia, with Thaliacea nested inside Phlebobranchia, although the deepest nodes of the Phlebobranchia–Thaliacea clade are not well resolved. The strategy described here thus provides a cost-effective approach to obtain complete mitogenomes characterized by a highly plastic gene order and a fast nucleotide/amino acid substitution rate. PMID:23709623

  5. Deep sequencing of mixed total DNA without barcodes allows efficient assembly of highly plastic ascidian mitochondrial genomes.

    PubMed

    Rubinstein, Nimrod D; Feldstein, Tamar; Shenkar, Noa; Botero-Castro, Fidel; Griggio, Francesca; Mastrototaro, Francesco; Delsuc, Frédéric; Douzery, Emmanuel J P; Gissi, Carmela; Huchon, Dorothée

    2013-01-01

    Ascidians or sea squirts form a diverse group within chordates, which includes a few thousand members of marine sessile filter-feeding animals. Their mitochondrial genomes are characterized by particularly high evolutionary rates and rampant gene rearrangements. This extreme variability complicates standard polymerase chain reaction (PCR) based techniques for molecular characterization studies, and consequently only a few complete Ascidian mitochondrial genome sequences are available. Using the standard PCR and Sanger sequencing approach, we produced the mitochondrial genome of Ascidiella aspersa only after a great effort. In contrast, we produced five additional mitogenomes (Botrylloides aff. leachii, Halocynthia spinosa, Polycarpa mytiligera, Pyura gangelion, and Rhodosoma turcicum) with a novel strategy, consisting in sequencing the pooled total DNA samples of these five species using one Illumina HiSeq 2000 flow cell lane. Each mitogenome was efficiently assembled in a single contig using de novo transcriptome assembly, as de novo genome assembly generally performed poorly for this task. Each of the new six mitogenomes presents a different and novel gene order, showing that no syntenic block has been conserved at the ordinal level (in Stolidobranchia and in Phlebobranchia). Phylogenetic analyses support the paraphyly of both Ascidiacea and Phlebobranchia, with Thaliacea nested inside Phlebobranchia, although the deepest nodes of the Phlebobranchia-Thaliacea clade are not well resolved. The strategy described here thus provides a cost-effective approach to obtain complete mitogenomes characterized by a highly plastic gene order and a fast nucleotide/amino acid substitution rate.

  6. Ascidians (Tunicata) of the French Guiana Expedition.

    PubMed

    Monniot, Françoise

    2016-05-24

    Ascidians were collected along the shore of Iles du Salut and deeper on the slope in a program of evaluation of the biodiversity in Guiana. Most of the samples belong to already known species from the Caribbean area and Brazilian coast. The colonial forms dominate. The 6 new species have been dredged deeper than 50m but not found by SCUBA divers. In spite of an intensive sampling, the ascidian diversity in Guiana is low with 36 species recorded. This is the result of the abundance of sediment suspended in the water and uniformly deposited on all substrates which affects filtration rate and limits the settling of the ascidian larvae.

  7. Halocyntin and papillosin, two new antimicrobial peptides isolated from hemocytes of the solitary tunicate, Halocynthia papillosa.

    PubMed

    Galinier, Richard; Roger, Emmanuel; Sautiere, Pierre-Eric; Aumelas, Andre; Banaigs, Bernard; Mitta, Guillaume

    2009-01-01

    We report here the screening of five marine invertebrate species from two taxa (tunicates and echinoderms) for the presence of cationic antimicrobial peptides (AMP) in defence cells (hemocytes). Antimicrobial activities were detected only in the two tunicates Microcosmus sabatieri and Halocynthia papillosa. In addition, we report the isolation and characterization of two novel peptides from H. papillosa hemocytes. These molecules display antibacterial activity against Gram-positive and Gram-negative bacteria. Complete peptide characterization was obtained by a combination of Edman degradation and mass spectrometry. The mature molecules, named halocyntin and papillosin, comprise 26 and 34 amino acid residues, respectively. Their primary structure display no significant similarities with previously described AMP.

  8. Mutation studies in ascidians: a review.

    PubMed

    Crocetta, Fabio; Marino, Rita; Cirino, Paola; Macina, Alberto; Staiano, Leopoldo; Esposito, Rosaria; Pezzotti, Maria Rosa; Racioppi, Claudia; Toscano, Francesco; De Felice, Elena; Locascio, Annamaria; Ristoratore, Filomena; Spagnuolo, Antonietta; Zanetti, Laura; Branno, Margherita; Sordino, Paolo

    2015-01-01

    Historically, mutations have had a significant impact on the study of developmental processes and phenotypic evolution. Lesions in DNA are created by artificial methods or detected by natural genetic variation. Random mutations are then ascribed to genetic change by direct sequencing or positional cloning. Tunicate species of the ascidian genus Ciona represent nearly fully realized model systems in which gene function can be investigated in depth. Additionally, tunicates are valuable organisms for the study of naturally occurring mutations due to the capability to exploit genetic variation down to the molecular level. Here, we summarize the available information about how mutations are studied in ascidians with examples of insights that have resulted from these applications. We also describe notions and methodologies that might be useful for the implementation of easy and tight procedures for mutations studies in Ciona.

  9. Species specificity of symbiosis and secondary metabolism in ascidians.

    PubMed

    Tianero, Ma Diarey B; Kwan, Jason C; Wyche, Thomas P; Presson, Angela P; Koch, Michael; Barrows, Louis R; Bugni, Tim S; Schmidt, Eric W

    2015-03-01

    Ascidians contain abundant, diverse secondary metabolites, which are thought to serve a defensive role and which have been applied to drug discovery. It is known that bacteria in symbiosis with ascidians produce several of these metabolites, but very little is known about factors governing these 'chemical symbioses'. To examine this phenomenon across a wide geographical and species scale, we performed bacterial and chemical analyses of 32 different ascidians, mostly from the didemnid family from Florida, Southern California and a broad expanse of the tropical Pacific Ocean. Bacterial diversity analysis showed that ascidian microbiomes are highly diverse, and this diversity does not correlate with geographical location or latitude. Within a subset of species, ascidian microbiomes are also stable over time (R=-0.037, P-value=0.499). Ascidian microbiomes and metabolomes contain species-specific and location-specific components. Location-specific bacteria are found in low abundance in the ascidians and mostly represent strains that are widespread. Location-specific metabolites consist largely of lipids, which may reflect differences in water temperature. By contrast, species-specific bacteria are mostly abundant sequenced components of the microbiomes and include secondary metabolite producers as major components. Species-specific chemicals are dominated by secondary metabolites. Together with previous analyses that focused on single ascidian species or symbiont type, these results reveal fundamental properties of secondary metabolic symbiosis. Different ascidian species have established associations with many different bacterial symbionts, including those known to produce toxic chemicals. This implies a strong selection for this property and the independent origin of secondary metabolite-based associations in different ascidian species. The analysis here streamlines the connection of secondary metabolite to producing bacterium, enabling further biological and

  10. Species specificity of symbiosis and secondary metabolism in ascidians

    PubMed Central

    Tianero, Ma Diarey B; Kwan, Jason C; Wyche, Thomas P; Presson, Angela P; Koch, Michael; Barrows, Louis R; Bugni, Tim S; Schmidt, Eric W

    2015-01-01

    Ascidians contain abundant, diverse secondary metabolites, which are thought to serve a defensive role and which have been applied to drug discovery. It is known that bacteria in symbiosis with ascidians produce several of these metabolites, but very little is known about factors governing these ‘chemical symbioses'. To examine this phenomenon across a wide geographical and species scale, we performed bacterial and chemical analyses of 32 different ascidians, mostly from the didemnid family from Florida, Southern California and a broad expanse of the tropical Pacific Ocean. Bacterial diversity analysis showed that ascidian microbiomes are highly diverse, and this diversity does not correlate with geographical location or latitude. Within a subset of species, ascidian microbiomes are also stable over time (R=−0.037, P-value=0.499). Ascidian microbiomes and metabolomes contain species-specific and location-specific components. Location-specific bacteria are found in low abundance in the ascidians and mostly represent strains that are widespread. Location-specific metabolites consist largely of lipids, which may reflect differences in water temperature. By contrast, species-specific bacteria are mostly abundant sequenced components of the microbiomes and include secondary metabolite producers as major components. Species-specific chemicals are dominated by secondary metabolites. Together with previous analyses that focused on single ascidian species or symbiont type, these results reveal fundamental properties of secondary metabolic symbiosis. Different ascidian species have established associations with many different bacterial symbionts, including those known to produce toxic chemicals. This implies a strong selection for this property and the independent origin of secondary metabolite-based associations in different ascidian species. The analysis here streamlines the connection of secondary metabolite to producing bacterium, enabling further biological and

  11. Two Decades of Ascidian Developmental Biology: A Personal Research Story.

    PubMed

    Satoh, Noriyuki

    2016-01-01

    Ascidians are the closest relatives of vertebrates. Their utility in experimental embryology has been well recognized because of their simple mode of embryogenesis to form tadpole larvae with a basal chordate body plan. Approximately two decades of research, including decoding of the Ciona genome, have promoted ascidians as one of the best systems for exploring genome-wide mechanisms of developmental transcriptional control and chordate evolution.

  12. Diversity of Actinobacteria Associated with the Marine Ascidian Eudistoma toealensis.

    PubMed

    Steinert, Georg; Taylor, Michael W; Schupp, Peter J

    2015-08-01

    Ascidians have yielded a wide variety of bioactive natural products. The colonial ascidian Eudistoma toealensis from Micronesia has been identified as the source of a series of staurosporine derivatives, though the exact origin of these derivatives is still unknown. To identify known staurosporine-producing microbes associated with E. toealensis, we analyzed with 16S rRNA gene tag pyrosequencing the overall bacterial community and focused on potential symbiotic bacteria already known from other ascidians or other marine hosts, such as sponges. The described microbiota was one of very high diversity, comprising 43 phyla: two from archaea, 34 described bacterial phyla, and seven candidate bacterial phyla. Many bacteria, which are renowned community members of other ascidians and marine holobionts, such as sponges and corals, were also part of the E. toealensis microbial community. Furthermore, two known producers of indolocarbazoles, Salinispora and Verrucosispora, were found with high abundance exclusively in the ascidian tissue, suggesting that microbial symbionts and not the organism itself may be the true producers of the staurosporines in E. toealensis.

  13. The ascidian pigmented sensory organs: structures and developmental programs.

    PubMed

    Esposito, R; Racioppi, C; Pezzotti, M R; Branno, M; Locascio, A; Ristoratore, F; Spagnuolo, A

    2015-01-01

    The recent advances on ascidian pigment sensory organ development and function represent a fascinating platform to get insight on the basic programs of chordate eye formation. This review aims to summarize current knowledge, at the structural and molecular levels, on the two main building blocks of ascidian light sensory organ, i.e. pigment cells and photoreceptor cells. The unique features of these structures (e.g., simplicity and well characterized cell lineage) are indeed making it possible to dissect the developmental programs at single cell resolution and will soon provide a panel of molecular tools to be exploited for a deep developmental and comparative-evolutionary analysis.

  14. Delineating metamorphic pathways in the ascidian Ciona intestinalis.

    PubMed

    Nakayama-Ishimura, Akie; Chambon, Jean-phillippe; Horie, Takeo; Satoh, Nori; Sasakura, Yasunori

    2009-02-15

    In most ascidians, metamorphosis of tadpole-like swimming larvae is accompanied by dynamic changes in their shape to form sessile adults. The mechanisms underlying ascidian metamorphosis have been debated for a long time. Although recent molecular studies have revealed the presence of various molecules involving in this process, the basic mechanism of the metamorphic events is still unclear. For example, it has not been solved whether all metamorphic events are organized by the same single pathway or by multiple, independent pathways. In the present study, we approached this question using the ascidian Ciona intestinalis. When the papillae and preoral lobes of the larvae were cut off, the papillae-cut larvae initiated certain trunk metamorphic events such as the formation of an ampulla, body axis rotation and adult organ growth without other metamorphic events. This observation indicates that metamorphic events can be divided into at least two groups, events initiated in the papillae-cut larva and events not initiated in this larva. In addition to this observation, we have isolated a novel mutant, tail regression failed (trf), which shows similar phenotypes to those of papillae-cut larvae. The phenotypes of trf mutants are basically different from those of swimming juvenile mutants (Sasakura, Y., Nakashima, K., Awazu, S., Matsuoka, T., Nakayama, A., Azuma, J., Satoh, N., 2005. Transposon-mediated insertional mutagenesis revealed the functions of animal cellulose synthase in the ascidian Ciona intestinalis. Proc. Natl. Acad. Sci. U. S. A. 102, 15134-15139.), which also show abnormal metamorphosis. These findings suggest a model by which ascidian metamorphic events can be classified into four groups initiated by different pathways.

  15. The Comparative Organismal Approach in Evolutionary Developmental Biology: Insights from Ascidians and Cavefish.

    PubMed

    Jeffery, William R

    2016-01-01

    Important contributions to evolutionary developmental biology have been made using the comparative organismal approach. As examples, I describe insights obtained from studies of Molgula ascidians and Astyanax cavefish.

  16. The evolution of larval morphology and swimming performance in ascidians.

    PubMed

    McHenry, Matthew J; Patek, Sheila N

    2004-06-01

    The complexity of organismal function challenges our ability to understand the evolution of animal locomotion. To meet this challenge, we used a combination of biomechanics, phylogenetic comparative analyses, and theoretical morphology to examine evolutionary changes in body shape and how those changes affected swimming performance in ascidian larvae. Results of phylogenetic comparative analyses suggest that coloniality evolved at least three times among ascidians and that colonial species have a convergent larval morphology characterized by a large trunk volume and shorter tail length in proportion to the trunk. To explore the functional significance of this evolutionary change, we first verified the accuracy of a mathematical model of swimming biomechanics in a solitary (C. intestinalis) and a colonial (D. occidentalis) species and then ran numerous simulations of the model that varied in tail length and trunk volume. The results of these simulations were used to construct landscapes of speed and cost of transport predictions within a trunk volume/tail length morphospace. Our results suggest that the reduction of proportionate tail length in colonial species resulted in improved energetic economy of swimming. The increase in the size of larvae with the origin of coloniality facilitated faster swimming with negligible energetic cost, but may have required a reduction in adult fecundity. Therefore, the evolution of ascidians appears to be influenced by a trade-off between the fecundity of the adult stage and the swimming performance of larvae.

  17. Temporal stability of bacterial symbionts in a temperate ascidian

    PubMed Central

    López-Legentil, Susanna; Turon, Xavier; Espluga, Roger; Erwin, Patrick M.

    2015-01-01

    In temperate seas, both bacterioplankton communities and invertebrate lifecycles follow a seasonal pattern. To investigate whether the bacterial community associated with the Mediterranean ascidian Didemnum fulgens exhibited similar variations, we monitored its bacterial community structure monthly for over a year using terminal restriction fragment length polymorphism and clone library analyses based on a nearly full length fragment of the 16S rRNA gene. D. fulgens harbored a bacterial consortium typical of ascidians, including numerous members of the phylum Proteobacteria, and a few members of the phyla Cyanobacteria and Acidobacteria. The overall bacterial community in D. fulgens had a distinct signature from the surrounding seawater and was stable over time and across seasonal fluctuations in temperature. Bacterial symbionts were also observed around animal cells in the tunic of adult individuals and in the inner tunic of D. fulgens larvae by transmission electron microscopy. Our results suggest that, as seen for sponges and corals, some species of ascidians host stable and unique bacterial communities that are at least partially inherited by their progeny by vertical transmission. PMID:26441944

  18. New distributional data on ascidian fauna (Tunicata: Ascidiacea) from Mandapam coast, Gulf of Mannar, India

    PubMed Central

    Akram, Soban A; Arshan, Kaleem ML

    2016-01-01

    Abstract Background Ascidians play a key role in the ecology and biodiversity of marine ecosystem. Ascidians can be transported in ship ballast water and while attached to ship and boat hulls. Heavy traffic by domestic and international ships as well as cargo vessels between the major and minor ports warrants continuous monitoring for new introductions of ascidians. The Mandapam coast is situated in the Gulf of Mannar, India, a marine hot spot area in the Indian Ocean which provides an environment suitable for the settlement of ascidians. New information A total of 30 species of ascidians were reported from Mandapam coastal waters, of which 26 species were new to the study area and five species: Ecteinascidia turbinata, Eudistoma carnosum, Trididemnum caelatum, T. vermiforme and Didemnum spadix, were new to India. PMID:27099557

  19. Evolution and development of brain sensory organs in molgulid ascidians.

    PubMed

    Jeffery, William R

    2004-01-01

    The ascidian tadpole larva has two brain sensory organs containing melanocytes: the otolith, a gravity receptor, and the ocellus, part of a photoreceptor. One or both of these sensory organs are absent in molgulid ascidians. We show here that developmental changes leading to the loss of sensory pigment cells occur by different mechanisms in closely related molgulid species. Sensory pigment cells are formed through a bilateral determination pathway in which two or more precursor cells are specified as an equivalence group on each side of the embryo. The precursor cells subsequently converge at the midline after neurulation and undergo cell interactions that decide the fates of the otolith and ocellus. Molgula occidentalis and M. oculata, which exhibit a tadpole larva with an otolith but lacking an ocellus, have conserved the bilateral pigment cell determination pathway. Programmed cell death (PCD) is superimposed on this pathway late in development to eliminate the ocellus precursor and supernumerary pigment cells, which do not differentiate into either an otolith or ocellus. In contrast to molgulids with tadpole larvae, no pigment cell precursors are specified on either side of the M. occulta embryo, which forms a tailless (anural) larva lacking both sensory organs, suggesting that the bilateral pigment cell determination pathway has been lost. The bilateral pigment cell determination pathway and superimposed PCD can be restored in hybrids obtained by fertilizing M. occulta eggs with M. oculata sperm, indicating control by a zygotic process. We conclude that PCD plays an important role in the evolution and development of brain sensory organs in molgulid ascidians.

  20. Prochloron-ascidian symbioses: Photosynthetic potential and productivity

    NASA Technical Reports Server (NTRS)

    Lewin, R. A.; Cheng, L.; Alberte, R. S.

    1983-01-01

    The chlorophyll content of didemnid asidians with symbiotic algae (Prochloron) from oligotropic tropical marine waters around Palau, Western Carolin Islands is discussed. Several species contain as much chlorophyll per unit dry weight as many herbaceous crop plants and more than do other symbiotic associations such as lichens, green Hydra, etc. Their chlorphyllA/B ratios (3-9) were generally much lighter than those of angiosperms (2-4). Where they abound, Prochloron - ascidian symbiosis could make a major contribution to the productivity, especially in localized areas of tropical marine waters characterized by low nutrient levels and high irradiance.

  1. Photosymbiotic ascidians from Pari Island (Thousand Islands, Indonesia).

    PubMed

    Hirose, Euichi; Iskandar, Budhi Hascaryo; Wardiatno, Yusli

    2014-01-01

    Photosymbiotic ascidian fauna were surveyed in the subtidal zone off Pari Island in the Thousand Islands (Java Sea, Indonesia). Nine species were recorded: Didemnum molle, Trididemnum miniatum, Lissoclinum patella, L. punctatum, L. timorense, Diplosoma gumavirens, D. simile, D. simileguwa, and D. virens. All of these species have been previously recorded in the Ryukyu Archipelago, Japan. Diplosoma gumavirens and D. simileguwa were originally described from the Ryukyu Archipelago in 2009 and 2005, respectively, and all of the observed species are potentially widely distributed in Indo-West Pacific coral reefs.

  2. Photosymbiotic ascidians from Pari Island (Thousand Islands, Indonesia)

    PubMed Central

    Hirose, Euichi; Iskandar, Budhi Hascaryo; Wardiatno, Yusli

    2014-01-01

    Abstract Photosymbiotic ascidian fauna were surveyed in the subtidal zone off Pari Island in the Thousand Islands (Java Sea, Indonesia). Nine species were recorded: Didemnum molle, Trididemnum miniatum, Lissoclinum patella, L. punctatum, L. timorense, Diplosoma gumavirens, D. simile, D. simileguwa, and D. virens. All of these species have been previously recorded in the Ryukyu Archipelago, Japan. Diplosoma gumavirens and D. simileguwa were originally described from the Ryukyu Archipelago in 2009 and 2005, respectively, and all of the observed species are potentially widely distributed in Indo–West Pacific coral reefs. PMID:25061385

  3. Ascidian tunicate extracts attenuate rheumatoid arthritis in a collagen-induced murine model.

    PubMed

    Hong, Seong-Ho; Kwone, Jung-Taek; Lee, Jae-Ho; Lee, Somin; Lee, Ah Young; Cho, Won-Young; Bat-Erdene, Munkhjargal; Choi, Byeong-Dae; Cho, Myung-Haing

    2014-06-01

    Murine rheumatoid arthritis models are often used to investigate the potential therapeutic effects of candidate drugs. The present study has been conducted in order to investigate the therapeutic efficacy of ascidian tunicate extracts in a collagen-induced arthritis DBA1/J mice model. Four types of formulas, ascidian tunicate extracts (ATE), crude ascidian tunicate glycans (ATEC), ascidian tunicate extracts with licorice extracts (ATEL), and crude ascidian tunicate glycans with licorice extracts (ATECL) were orally administered into DBA/1J mice for 3 weeks and paw edema and thickness were evaluated. Changes in inflammatory proteins and cytokines levels were monitored in hind leg tissues by Western blot and quantitative PCR analysis. The oral administration of ascidian tunicate extracts alleviated paw edema and improved the histological hind leg cartilage status. The extracts also reduced the matrix metalloproteinase-9 (MMP-9) protein and prostaglandin E synthase (PGES) levels. In addition, the extracts-treated groups showed increased interleukin-10 (IL-10) levels compared with the non-treated group. These findings suggest that orally administered ascidian tunicate extracts might have potential therapeutic effects for the treatment of rheumatoid arthritis.

  4. Ascidians as excellent models for studying cellular events in the chordate body plan.

    PubMed

    Ogura, Yosuke; Sasakura, Yasunori

    2013-08-01

    The larvae of non-vertebrate chordate ascidians consist of countable numbers of cells. With this feature, ascidians provide us with excellent models for studying cellular events in the construction of the chordate body. This review discusses the recent observations of morphogenetic movements and cell cycles and divisions along with tissue specifications during ascidian embryogenesis. Unequal cleavages take place at the posterior blastomeres during the early cleavage stages of ascidians, and the structure named the centrosome-attracting body restricts the position of the nuclei near the posterior pole to achieve the unequal cleavages. The most-posterior cells differentiate into the primordial germ cells. The gastrulation of ascidians starts as early as the 110-cell stage. During gastrulation, the endodermal cells show two-step changes in cell shape that are crucial for gastrulation. The ascidian notochord is composed of only 40 cells. The 40 cells align to form a single row by an event named the convergent extension, and then the notochord cells undergo vacuolation to transform the notochord into a single hollowed tube. The strictly restricted number of notochord cells is achieved by the regulated number of cell divisions coupled with the differentiation of the cells conducted by a key transcription factor, Brachyury. The dorsally located neural tube is a characteristic of chordates. During the closure of the ascidian neural tube, the epidermis surrounding the neural plate moves toward the midline to close the neural fold. This morphogenetic movement is allowed by an elongation of interphase in the epidermal cell cycles.

  5. Bioadhesion in ascidians: a developmental and functional genomics perspective

    PubMed Central

    Pennati, Roberta; Rothbächer, Ute

    2015-01-01

    The development of bioadhesives inspired from marine animals is a promising approach to generate new tissue-compatible medical components. A number of marine species, through their adhesive properties, also represent significant foulers that become increasingly problematic to aquaculture, shipping or local biodiversity. In order to develop more sophisticated man-made glues and/or efficient fouling resistant surfaces, it is important to understand the mechanical, structural and molecular properties of adhesive organs in selected species. Ascidians are marine invertebrates with larvae that opportunistically attach to almost any type of submerged surface to undergo metamorphosis into permanently sessile adults. Not only do they represent a globally important fouling organism, but they are becoming increasingly popular as model organisms for developmental biology. The latter is due to their phylogenetic position as the sister group to the vertebrates and their cellular and molecular accessibility for experimentation. In this paper, we review the mechanisms of larval adhesion in ascidians and draw conclusions from comparative analyses of selected species. We further discuss how knowledge from a developmental and functional genomics point of view can advance our understanding of cellular and molecular signatures and their hierarchical usage in animal adhesive organs. PMID:25657840

  6. Photosymbiotic ascidians in Singapore: turbid waters may reduce living space

    PubMed Central

    Su, Shih-Wei; Hirose, Euichi; Chen, Serina Lee Siew; Mok, Michael Hin-Kiu

    2013-01-01

    Abstract The photosymbiotic ascidian fauna at Changi Beach, Pulau Semakau, Sentosa and St. John’s Island, Singapore were surveyed. A total of five species, Diplosoma simile, Lissoclinum bistratum, Lissoclinum punctatum, Lissoclinum timorense and Trididemnum cyclops, were recorded, with Lissoclinum timorense and Trididemnum cyclops being newly recorded in Singapore. However, no photosymbiotic species were found at Changi Beach probably due to the polluted waters in the region. Coastal development has caused Singapore waters to become turbid, leading to decrease in suitable habitats for photosymbiotic ascidians. Clean waters in Pulau Semakau probably provide a better environment for the growth of photosymbiotic ascidians and this area has a greater variety of these ascidians than the other areas in Singapore. Each of the five species has also been recorded in the Ryukyu Archipelago (Japan) and three species (Diplosoma simile, Lissoclinum bistratum and Trididemnum cyclops) have also been recorded in Taiwan. PMID:23794913

  7. The challenges of trafficking hydrolysis prone metals and ascidians as an archetype.

    PubMed

    Gaffney, Jean P; Valentine, Ann M

    2011-06-14

    Some of the metal ions that are required, exploited, or simply managed in biological systems are susceptible to hydrolysis and to hydrolytic precipitation in the aqueous, aerobic environment of much of biology. Organisms have evolved exquisite mechanisms for handling these metal ions, offering striking examples of biological control over inorganic coordination chemistry. This year marks the one hundredth anniversary of the discovery of remarkably high vanadium concentrations in the blood cells of the ascidian. In the ensuing years, these marine invertebrates were established as masters of the biological chemistry of very hydrolysis-prone metals, with various ascidian species accumulating high concentrations of iron, vanadium, and titanium, among others. These three metals have very different histories of biological relevance, and many questions remain about how, and ultimately why, these organisms sequester them. This Perspective addresses the aqueous coordination chemistry that organisms like ascidians must control if they are to manipulate hydrolysis-prone metal ions, and describes some of the ascidian biomolecules that have been implicated in this phenomenon. The recently available genome sequence for one ascidian species offers a glimpse into its metal-management arsenal. It offers the opportunity to map the relatively well-studied paradigm of iron management onto the genome of an organism that is intermediate in evolution between invertebrates and vertebrates. The ascidians have much to teach us about how to manage metals like iron, titanium, and vanadium and how that ability evolved.

  8. The retinoid X receptor in a marine invertebrate chordate: evolutionary insights from urochordates.

    PubMed

    Maeng, Sejung; Lee, Jung Hwan; Choi, Sung-Chang; Kim, Mi Ae; Shin, Yun Kyung; Sohn, Young Chang

    2012-09-01

    Retinoid X receptors (RXRs) are highly conserved members of the nuclear hormone receptor family that mediate various physiological processes in vertebrates and invertebrates. We examined the expression patterns of RXR in the ascidian Halocynthia roretzi across a wide range of tissues and stages of embryo development, as well as the regulation of gene transcription by the ascidian RXR. H. roretzi RXR cDNA (HrRXR) was cloned from 64-cell stage embryos. The overall amino acid sequence of HrRXR showed high sequence identity with a urochordate Ciona intestinalis RXR (58%), but the ligand-binding domain of HrRXR was more similar to vertebrate orthologs than to those of invertebrate RXRs. Based on a phylogenetic analysis, HrRXR belongs to a group of urochordates that are separate from vertebrate RXRs, showing a clear evolutionary history. Real-time quantitative polymerase chain reaction and whole-mount in situ hybridization analyses revealed that the HrRXR mRNA is of maternal origin during embryogenesis, and in the examined adult tissues it is expressed in the muscles, gills, gonads, and the hepatopancreas. Immunofluorescence and immunohistochemical staining demonstrated that HrRXR is localized to the nucleus and highly expressed in the gills and hepatopancreas. Unlike human RXRα, HrRXR did not show 9-cis retinoic acid- and bexarotene (LGD1069)-dependent transactivation. While a synthetic ligand for farnesoid X receptor (FXR), GW4064, did not increase the transcriptional activation in HrRXR- or HrRXR/HrFXR-transfected HEK-293 cells, the ligand showed weak but significant activity for a single amino acid mutant of HrRXR ((Phe)231(Cys)) and HrFXR cotransfected cells. The present study suggests that the marine invertebrate chordate RXR may possess endogenous ligands that are different than vertebrate RXR ligands and which function during early embryonic stages.

  9. Down under the tunic: bacterial biodiversity hotspots and widespread ammonia-oxidizing archaea in coral reef ascidians

    PubMed Central

    Erwin, Patrick M; Pineda, Mari Carmen; Webster, Nicole; Turon, Xavier; López-Legentil, Susanna

    2014-01-01

    Ascidians are ecologically important components of marine ecosystems yet the ascidian microbiota remains largely unexplored beyond a few model species. We used 16S rRNA gene tag pyrosequencing to provide a comprehensive characterization of microbial symbionts in the tunic of 42 Great Barrier Reef ascidian samples representing 25 species. Results revealed high bacterial biodiversity (3 217 unique operational taxonomic units (OTU0.03) from 19 described and 14 candidate phyla) and the widespread occurrence of ammonia-oxidizing Thaumarchaeota in coral reef ascidians (24 of 25 host species). The ascidian microbiota was clearly differentiated from seawater microbial communities and included symbiont lineages shared with other invertebrate hosts as well as unique, ascidian-specific phylotypes. Several rare seawater microbes were markedly enriched (200–700 fold) in the ascidian tunic, suggesting that the rare biosphere of seawater may act as a conduit for horizontal symbiont transfer. However, most OTUs (71%) were rare and specific to single hosts and a significant correlation between host relatedness and symbiont community similarity was detected, indicating a high degree of host-specificity and potential role of vertical transmission in structuring these communities. We hypothesize that the complex ascidian microbiota revealed herein is maintained by the dynamic microenvironments within the ascidian tunic, offering optimal conditions for different metabolic pathways such as ample chemical substrate (ammonia-rich host waste) and physical habitat (high oxygen, low irradiance) for nitrification. Thus, ascidian hosts provide unique and fertile niches for diverse microorganisms and may represent an important and previously unrecognized habitat for nitrite/nitrate regeneration in coral reef ecosystems. PMID:24152714

  10. Gut-spilling in chordates: evisceration in the tropical ascidian Polycarpa mytiligera.

    PubMed

    Shenkar, Noa; Gordon, Tal

    2015-04-16

    The ejection of internal organs, i.e., evisceration, is a well-known phenomenon in sea-cucumbers. We report the ability of a member of the Chordate phyla, the tropical ascidian Polycarpa mytiligera, to eviscerate and regenerate its gut within 12 days, and to rebuild its branchial sac within 19 days. Evisceration occurred within 4-43 seconds of gentle mechanical pressure exerted on the tunic in 47% of the tested P. mytiligera. Individuals were able to discard up to 3/4 of their digestive tract via the incurrent siphon by rupture of the branchial sac in this area. Although chemical analysis revealed no significant levels of toxic compounds, the eviscerated guts were unpalatable to the triggerfish and pufferfish on which they were tested, suggesting evisceration as a defense mechanism. Given the close affinity of ascidians to vertebrates, the regeneration pathway of the viscera and branchial sac of ascidians suggests its potential beneficial application in soft tissue regeneration research.

  11. Primary genetic linkage maps of the ascidian, Ciona intestinalis.

    PubMed

    Kano, Shungo; Satoh, Nori; Sordino, Paolo

    2006-01-01

    For whole-genome analysis in a basal chordate (protochordate), we used F1 pseudo-testcross mapping strategy and amplified fragment length polymorphism (AFLP) markers to construct primary linkage maps of the ascidian tunicate Ciona intestinalis. Two genetic maps consisted of 14 linkage groups, in agreement with the haploid chromosome number, and contained 276 and 125 AFLP loci derived from crosses between British and Neapolitan individuals. The two maps covered 4218.9 and 2086.9 cM, respectively, with an average marker interval of 16.1 and 18.9 cM. We observed a high recombinant ratio, ranging from 25 to 49 kb/cM, which can explain the high degree of polymorphism in this species. Some AFLP markers were converted to sequence tagged sites (STSs) by sequence determination, in order to create anchor markers for the fragmental physical map. Our recombination tools provide basic knowledge of genetic status and whole genome organization, and genetic markers to assist positional cloning in C. intestinalis.

  12. A chemoattractant for ascidian spermatozoa is a sulfated steroid

    PubMed Central

    Yoshida, Manabu; Murata, Michio; Inaba, Kazuo; Morisawa, Masaaki

    2002-01-01

    Sperm chemotaxis toward eggs before fertilization has been demonstrated in many animals and plants, and several peptides and small organic compounds acting as chemoattractants have been identified. We previously showed that sperm of the ascidians Ciona intestinalis and Ciona savignyi are activated and then attracted toward the egg by a common factor released from the egg. In this study, we purified sperm-activating and -attracting factor (SAAF) from the egg-conditioning medium of C. intestinalis by using several steps of column chromatography. Determination of the molecular structure by NMR and MS/MS analysis revealed that SAAF is a previously uncharacterized sulfated steroid: 3,4,7,26-tetrahydroxycholestane-3,26-disulfate. Furthermore, it was shown that the SAAF of C. savignyi was indistinguishable from that of C. intestinalis in terms of the chromatographic behavior and molecular weight, indicating that the same compound might be responsible for sperm activation and chemotaxis in both the species. Furthermore, we established a method for quantitative analysis of sperm chemotaxis and showed that the chemotactic behavior of Ciona sperm is controlled by the “chemotactic turn” associated with decrease in the concentration of SAAF. PMID:12411583

  13. Genetic signatures of natural selection in a model invasive ascidian

    NASA Astrophysics Data System (ADS)

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-03-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta.

  14. Sexual and asexual reproduction in the colonial ascidian Botryllus schlosseri.

    PubMed

    Gasparini, Fabio; Manni, Lucia; Cima, Francesca; Zaniolo, Giovanna; Burighel, Paolo; Caicci, Federico; Franchi, Nicola; Schiavon, Filippo; Rigon, Francesca; Campagna, Davide; Ballarin, Loriano

    2015-01-01

    The colonial tunicate Botryllus schlosseri is a widespread filter-feeding ascidian that lives in shallow waters and is easily reared in aquaria. Its peculiar blastogenetic cycle, characterized by the presence of three blastogenetic generations (filtering adults, buds, and budlets) and by recurrent generation changes, has resulted in over 60 years of studies aimed at understanding how sexual and asexual reproduction are coordinated and regulated in the colony. The possibility of using different methodological approaches, from classical genetics to cell transplantation, contributed to the development of this species as a valuable model organism for the study of a variety of biological processes. Here, we review the main studies detailing rearing, staging methods, reproduction and colony growth of this species, emphasizing the asymmetry in sexual and asexual reproduction potential, sexual reproduction in the field and the laboratory, and self- and cross-fertilization. These data, opportunely matched with recent tanscriptomic and genomic outcomes, can give a valuable help to the elucidation of some important steps in chordate evolution.

  15. Delayed insemination results in embryo mortality in a brooding ascidian.

    PubMed

    Stewart-Savage, J; Phillippi, A; Yund, P O

    2001-08-01

    We explored the effects of temporal variation in sperm availability on fertilization and subsequent larval development in the colonial ascidian Botryllus schlosseri, a brooding hermaphrodite that has a sexual cycle linked to an asexual zooid replacement cycle. We developed a method to quantify the timing of events early in this cycle, and then isolated colonies before the start of the cycle and inseminated them at various times. Colony-wide fertilization levels (assayed by early cleavage) increased from zero to 100% during the period when the siphons of a new generation of zooids were first opening, and remained high for 24 h before slowly declining over the next 48 h. Because embryos are brooded until just before the zooids degenerate at the end of a cycle, delayed fertilization might also affect whether embryos can complete development within the cycle. Consequently, we also determined the effect of delayed insemination on successful embryo development through larval release and metamorphosis. When fertilization was delayed beyond the completion of siphon opening, there was an exponential decline in the percentage of eggs that ultimately produced a metamorphosed larva at the end of the cycle. Thus, even though the majority of oocytes can be fertilized when insemination is delayed for up to 48 h, the resulting embryos cannot complete development before the brooding zooids degenerate.

  16. Genetic signatures of natural selection in a model invasive ascidian

    PubMed Central

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-01-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta. PMID:28266616

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

    PubMed

    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.

  18. Proteomics of ionomycin-induced ascidian sperm reaction: Released and exposed sperm proteins in the ascidian Ciona intestinalis.

    PubMed

    Nakazawa, Shiori; Shirae-Kurabayashi, Maki; Otsuka, Kei; Sawada, Hitoshi

    2015-12-01

    Sperm proteins mediating sperm-egg interaction should be exhibited on the sperm surface, or exposed or released when sperm approach an egg. In ascidians (protochordates), sperm undergo a sperm reaction, characterized by enhanced sperm motility and mitochondrial swelling and shedding on contact with the vitelline coat (VC) or by treatment with Ca(2+) ionophore. Here, proteomic analysis was conducted on sperm exudates and sperm surface proteins using ionomycin-induced sperm reaction and cell-impermeable labeling in Ciona intestinalis type A (C. robusta). In the exudate from sperm treated with ionomycin, membrane proteins including a possible VC receptor CiUrabin were abundant, indicating the release of membranous compartments during sperm reaction. Among the surface proteins XP_009859314.1 (uncharacterized protein exhibiting homology to HrTTSP-1) was most abundant before the sperm reaction, but XP_004227079.1 (unknown Ig superfamily protein) appears to be most abundantly exposed by the sperm reaction. Moreover, proteins containing a notable set of domains, astacin-like metalloprotease domain and thrombospondin type 1 repeat(s), were found in this fraction. Possible roles in fertilization as well as localizations and behaviors of these proteins are discussed.

  19. Ascidians as excellent chordate models for studying the development of the nervous system during embryogenesis and metamorphosis.

    PubMed

    Sasakura, Yasunori; Mita, Kaoru; Ogura, Yosuke; Horie, Takeo

    2012-04-01

    The swimming larvae of the chordate ascidians possess a dorsal hollowed central nervous system (CNS), which is homologous to that of vertebrates. Despite the homology, the ascidian CNS consists of a countable number of cells. The simple nervous system of ascidians provides an excellent experimental system to study the developmental mechanisms of the chordate nervous system. The neural fate of the cells consisting of the ascidian CNS is determined in both autonomous and non-autonomous fashion during the cleavage stage. The ascidian neural plate performs the morphogenetic movement of neural tube closure that resembles that in vertebrate neural tube formation. Following neurulation, the CNS is separated into five distinct regions, whose homology with the regions of vertebrate CNS has been discussed. Following their larval stage, ascidians undergo a metamorphosis and become sessile adults. The metamorphosis is completed quickly, and therefore the metamorphosis of ascidians is a good experimental system to observe the reorganization of the CNS during metamorphosis. A recent study has shown that the major parts of the larval CNS remain after the metamorphosis to form the adult CNS. In contrast to such a conserved manner of CNS reorganization, most larval neurons disappear during metamorphosis. The larval glial cells in the CNS are the major source for the formation of the adult CNS, and some of the glial cells produce adult neurons.

  20. Multiple origins of the ascidian-Prochloron symbiosis: molecular phylogeny of photosymbiotic and non-symbiotic colonial ascidians inferred from 18S rDNA sequences.

    PubMed

    Yokobori, Shin-Ichi; Kurabayashi, Atsushi; Neilan, Brett A; Maruyama, Tadashi; Hirose, Euichi

    2006-07-01

    In the tropics, certain didemnid ascidians harbor the prokaryotic photosymbiont Prochloron. To date, this photosymbiosis has been found in four didemnid genera that include non-symbiotic species. Here, we report the molecular phylogeny of symbiotic and non-symbiotic didemnids based on their 18S rDNA sequences. The data cover all four genera containing symbiotic species and one other genus comprised of only non-symbiotic species. Near-complete nucleotide sequences of 18S rDNAs were determined for four non-didemnid species and 52 didemnid samples (five genera), including 48 photosymbiotic samples collected from the Ryukyu Archipelago, the Great Barrier Reef, Hawaii, and Bali. Our phylogenetic trees indicated a monophyletic origin of the family Didemnidae, as well as each of the didemnid genera. The results strongly support the hypothesis that establishment of the ascidian-Prochloron symbiosis occurred independently in the Didemnidae lineage at least once in each of the genera that possess symbiotic species.

  1. Blood circulation in the ascidian tunicate Corella inflata (Corellidae)

    PubMed Central

    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

  2. Blood circulation in the ascidian tunicate Corella inflata (Corellidae).

    PubMed

    Konrad, Michael W

    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.

  3. Patellamide E: a new cyclic peptide from the ascidian Lissoclinum patella.

    PubMed

    McDonald, L A; Ireland, C M

    1992-03-01

    A new cyclic peptide, patellamide E [1], was isolated from the ascidian Lissoclinum patella collected at Pulau Salu, Singapore. Its structure was determined by nmr spectroscopy, and its absolute configuration by acid hydrolysis and analysis of the derivatized constituent amino acids by hplc. Patellamide E was mildly cytotoxic against human colon tumor cells in vitro.

  4. ANISEED 2015: a digital framework for the comparative developmental biology of ascidians.

    PubMed

    Brozovic, Matija; Martin, Cyril; Dantec, Christelle; Dauga, Delphine; Mendez, Mickaël; Simion, Paul; Percher, Madeline; Laporte, Baptiste; Scornavacca, Céline; Di Gregorio, Anna; Fujiwara, Shigeki; Gineste, Mathieu; Lowe, Elijah K; Piette, Jacques; Racioppi, Claudia; Ristoratore, Filomena; Sasakura, Yasunori; Takatori, Naohito; Brown, Titus C; Delsuc, Frédéric; Douzery, Emmanuel; Gissi, Carmela; McDougall, Alex; Nishida, Hiroki; Sawada, Hitoshi; Swalla, Billie J; Yasuo, Hitoyoshi; Lemaire, Patrick

    2016-01-04

    Ascidians belong to the tunicates, the sister group of vertebrates and are recognized model organisms in the field of embryonic development, regeneration and stem cells. ANISEED is the main information system in the field of ascidian developmental biology. This article reports the development of the system since its initial publication in 2010. Over the past five years, we refactored the system from an initial custom schema to an extended version of the Chado schema and redesigned all user and back end interfaces. This new architecture was used to improve and enrich the description of Ciona intestinalis embryonic development, based on an improved genome assembly and gene model set, refined functional gene annotation, and anatomical ontologies, and a new collection of full ORF cDNAs. The genomes of nine ascidian species have been sequenced since the release of the C. intestinalis genome. In ANISEED 2015, all nine new ascidian species can be explored via dedicated genome browsers, and searched by Blast. In addition, ANISEED provides full functional gene annotation, anatomical ontologies and some gene expression data for the six species with highest quality genomes. ANISEED is publicly available at: http://www.aniseed.cnrs.fr.

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

    PubMed Central

    Degasperi, Valentina; Gasparini, Fabio; Shimeld, Sebastian M; Sinigaglia, Chiara; Burighel, Paolo; Manni, Lucia

    2009-01-01

    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. PMID:19737381

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

    PubMed Central

    Núñez-Pons, Laura; Carbone, Marianna; Vázquez, Jennifer; Rodríguez, Jaime; Nieto, Rosa María; Varela, María Mercedes; Gavagnin, Margherita; Avila, Conxita

    2012-01-01

    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. PMID:23015772

  7. Ascidian (Chordata-Tunicata) glycosaminoglycans: extraction, purification, biochemical, and spectroscopic analysis.

    PubMed

    Pavão, Mauro S G

    2015-01-01

    Sulfated polysaccharides with unique structures of the chondroitin/dermatan and heparin/heparan families of sulfated glycosaminoglycans have been described in several species of ascidians (Chordata-Tunicata). These unique sulfated glycans have been isolated from-ascidians and characterized by biochemical and spectroscopic methods. The ascidian glycans can be extracted by different tissues or cells by proteolytic digestion followed by cetylpyridinium chloride/ethanol precipitation. The total glycans are then fractionated by ion-exchange chromatography on DEAE-cellulose and/or Mono Q (HR 5/5) columns. Alternatively, precipitation with different ethanol concentrations can be employed. An initial analysis of the purified ascidian glycans is carried out by agarose gel electrophoresis on diaminopropane/acetate buffer, before or after digestion with specific glycosaminoglycan lyases or deaminative cleavage with nitrous acid. The disaccharides formed by exhaustive degradation of the glycans is purified by gel-filtration chromatography on a Superdex-peptide column and analyzed by HPLC on a strong ion exchange Sax-Spherisorb column. 1H or 13C nuclear magnetic resonance spectroscopy in one or two dimensions is used to confirm the structure of the intact glycans.

  8. ANISEED 2015: a digital framework for the comparative developmental biology of ascidians

    PubMed Central

    Brozovic, Matija; Martin, Cyril; Dantec, Christelle; Dauga, Delphine; Mendez, Mickaël; Simion, Paul; Percher, Madeline; Laporte, Baptiste; Scornavacca, Céline; Di Gregorio, Anna; Fujiwara, Shigeki; Gineste, Mathieu; Lowe, Elijah K.; Piette, Jacques; Racioppi, Claudia; Ristoratore, Filomena; Sasakura, Yasunori; Takatori, Naohito; Brown, Titus C.; Delsuc, Frédéric; Douzery, Emmanuel; Gissi, Carmela; McDougall, Alex; Nishida, Hiroki; Sawada, Hitoshi; Swalla, Billie J.; Yasuo, Hitoyoshi; Lemaire, Patrick

    2016-01-01

    Ascidians belong to the tunicates, the sister group of vertebrates and are recognized model organisms in the field of embryonic development, regeneration and stem cells. ANISEED is the main information system in the field of ascidian developmental biology. This article reports the development of the system since its initial publication in 2010. Over the past five years, we refactored the system from an initial custom schema to an extended version of the Chado schema and redesigned all user and back end interfaces. This new architecture was used to improve and enrich the description of Ciona intestinalis embryonic development, based on an improved genome assembly and gene model set, refined functional gene annotation, and anatomical ontologies, and a new collection of full ORF cDNAs. The genomes of nine ascidian species have been sequenced since the release of the C. intestinalis genome. In ANISEED 2015, all nine new ascidian species can be explored via dedicated genome browsers, and searched by Blast. In addition, ANISEED provides full functional gene annotation, anatomical ontologies and some gene expression data for the six species with highest quality genomes. ANISEED is publicly available at: http://www.aniseed.cnrs.fr. PMID:26420834

  9. Monoaminergic modulation of photoreception in ascidian: evidence for a proto-hypothalamo-retinal territory

    PubMed Central

    2012-01-01

    Background The retina of craniates/vertebrates has been proposed to derive from a photoreceptor prosencephalic territory in ancestral chordates, but the evolutionary origin of the different cell types making the retina is disputed. Except for photoreceptors, the existence of homologs of retinal cells remains uncertain outside vertebrates. Methods The expression of genes expressed in the sensory vesicle of the ascidian Ciona intestinalis including those encoding components of the monoaminergic neurotransmission systems, was analyzed by in situ hybridization or in vivo transfection of the corresponding regulatory elements driving fluorescent reporters. Modulation of photic responses by monoamines was studied by electrophysiology combined with pharmacological treatments. Results We show that many molecular characteristics of dopamine-synthesizing cells located in the vicinity of photoreceptors in the sensory vesicle of the ascidian Ciona intestinalis are similar to those of amacrine dopamine cells of the vertebrate retina. The ascidian dopamine cells share with vertebrate amacrine cells the expression of the key-transcription factor Ptf1a, as well as that of dopamine-synthesizing enzymes. Surprisingly, the ascidian dopamine cells accumulate serotonin via a functional serotonin transporter, as some amacrine cells also do. Moreover, dopamine cells located in the vicinity of the photoreceptors modulate the light-off induced swimming behavior of ascidian larvae by acting on alpha2-like receptors, instead of dopamine receptors, supporting a role in the modulation of the photic response. These cells are located in a territory of the ascidian sensory vesicle expressing genes found both in the retina and the hypothalamus of vertebrates (six3/6, Rx, meis, pax6, visual cycle proteins). Conclusion We propose that the dopamine cells of the ascidian larva derive from an ancestral multifunctional cell population located in the periventricular, photoreceptive field of the anterior

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

    PubMed

    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.

  11. Ascidian fauna (Tunicata, Ascidiacea) of subantarctic and temperate regions of Chile.

    PubMed

    Turon, Xavier; Cañete, Juan I; Sellanes, Javier; Rocha, Rosana M; López-Legentil, Susanna

    2016-03-21

    We studied the ascidian fauna from two zones located in subantarctic (Punta Arenas, latitude 53º) and temperate Chile (Coquimbo, latitude 29º). The different oceanographic features of the two zones, with influence of the Humboldt Current in the north and the Cape Horn Current System and freshwater inputs in the south, led to markedly different ascidian faunas. A total of 22 species were recorded, with no shared species across the two areas (11 species each). The new species Polyzoa iosune is described, Lissoclinum perforatum is found for the first time in the Pacific Ocean, and Synoicum georgianum and Polyzoa minor are new to the Chilean fauna. The populations of Ciona in the Coquimbo area (formerly attributed to Ciona intestinalis) correspond to the species Ciona robusta. A total of 35 Cytochrome oxidase (COI) sequences of the standard barcode region have been obtained for 17 of the 22 species reported.

  12. Inducible galectins are expressed in the inflamed pharynx of the ascidian Ciona intestinalis.

    PubMed

    Vizzini, Aiti; Parrinello, Daniela; Sanfratello, Maria Antonietta; Salerno, Giuseppina; Cammarata, Matteo; Parrinello, Nicolò

    2012-01-01

    Although ascidians belong to a key group in chordate phylogenesis, amino acid sequences of Ciona intestinalis galectin-CRDs (CiLgals-a and -b) have been retained too divergent from vertebrate galectins. In the present paper, to contribute in disclosing Bi-CRD galectin evolution a novel attempt was carried out on CiLgals-a and -b CRDs phylogenetic analysis, and their involvement in ascidian inflammatory responses was shown. CiLgals resulted aligned with Bi-CRD galectins from vertebrates (Xenopus tropicalis, Gallus gallus, Mus musculus, Homo sapiens), cephalochordates (Branchiostoma floridae), echinoderms (Strongylocentrotus purpuratus) and a mono-CRD galectin from the ascidian Clavelina picta. The CiLgals-a N-terminal and C-terminal CRDs contain the signature sequence involved in carbohydrate binding, whereas the CiLgals-b C-CRD presents only three out of seven key aminoacids and it could not be suitable as sugar binding motif. Sequence similarity between clusters suggests an evolutionary model based on CRD domain gene duplication and sequence diversification. In particular CiLgals-b N-CRD and C-CRD were similar to each other and both grouped with the ascidian C. picta mono-CRD. Homology modeling process shows a CiLgals molecular structure superimposed to chicken and mouse galectins. The CiLgals-a and CiLgals-b genes were upregulated by LPS inoculation suggesting that they are inducible and expressed in the inflamed pharynx as revealed by real-time PCR analysis. Finally, in situ hybridization and immunohistochemical assays showed their localization in the inflamed tissues, while immunoblotting analysis indicated that CiLgals can form oligomers.

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

    PubMed

    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.

  14. Quinone and Hydroquinone Metabolites from the Ascidians of the Genus Aplidium

    PubMed Central

    Bertanha, Camila Spereta; Januário, Ana Helena; Alvarenga, Tavane Aparecida; Pimenta, Letícia Pereira; e Silva, Márcio Luis Andrade; Cunha, Wilson Roberto; Pauletti, Patrícia Mendonça

    2014-01-01

    Ascidians of the genus Aplidium are recognized as an important source of chemical diversity and bioactive natural products. Among the compounds produced by this genus are non-nitrogenous metabolites, mainly prenylated quinones and hydroquinones. This review discusses the isolation, structural elucidation, and biological activities of quinones, hydroquinones, rossinones, longithorones, longithorols, floresolides, scabellones, conicaquinones, aplidinones, thiaplidiaquinones, and conithiaquinones. A compilation of the 13C-NMR spectral data of these compounds is also presented. PMID:24927227

  15. The alien ascidian Styela clava now invading the Sea of Marmara (Tunicata: Ascidiacea).

    PubMed

    Çinar, Melih Ertan

    2016-01-01

    During the implementation of a large project aimed to investigate the benthic community structures of the Sea of Marmara, specimens of the invasive ascidian species Styela clava were collected on natural substrata (rocks) at 10 m depth at one locality (Karamürsel) in İzmit Bay. The specimens were mature, containing gametes, indicating that the species had become established in the area. The Sea of Marmara seems to provide suitable conditions for this species to survive and form proliferating populations.

  16. Shallow-water Ascidians from Matua Island (central Kuril Islands, NW Pacific).

    PubMed

    Sanamyan, Karen; Sanamyan, Nadya

    2017-02-16

    Fifteen species of ascidians were identified in the material collected at Matua Island. Two species are new, Botryllus flavus n. sp. and Distaplia matua n. sp. The first species occurs also at Kamchatka waters, while the second is probably an endemic of Kuril Islands. The genus Macrenteron Redikorzev, 1927 is synonymized with Aplidium Savigny, 1816 and a new name Aplidium macrenteron nom. nov. is proposed for its type species.

  17. Ammonia-oxidizing Crenarchaeota and nitrification inside the tissue of a colonial ascidian.

    PubMed

    Martínez-García, Manuel; Stief, Peter; Díaz-Valdés, Marta; Wanner, Gerhard; Ramos-Esplá, Alfonso; Dubilier, Nicole; Antón, Josefa

    2008-11-01

    Marine Crenarchaeota represent an abundant component of the oceanic microbiota that play an important role in the global nitrogen cycle. Here we report the association of the colonial ascidian Cystodytes dellechiajei with putative ammonia-oxidizing Crenarchaeota that could actively be involved in nitrification inside the animal tissue. As shown by 16S rRNA gene analysis, the ascidian-associated Crenarchaeota were phylogenetically related to Nitrosopumilus maritimus, the first marine archaeon isolated in pure culture that grows chemolithoautotrophically oxidizing ammonia to nitrite aerobically. Catalysed reporter deposition (CARD)-FISH revealed that the Crenarchaeota were specifically located inside the tunic tissue of the colony, where moreover the expression of amoA gene was detected. The amoA gene encodes the alpha-subunit of ammonia monooxygenase, which is involved in the first step of nitrification, the oxidation of ammonia to nitrite. Sequencing of amoA gene showed that they were phylogenetically related to amoA genes of N. maritimus and other putative ammonia-oxidizing marine Crenarchaeota. In order to track the suspected nitrification activity inside the ascidian colony under in vivo conditions, microsensor profiles were measured through the tunic tissue. Net NO(x) production was detected in the tunic layer 1200-1800 microm with rates of 58-90 nmol cm(-3) h(-1). Oxygen and pH microsensor profiles showed that the layer of net NO(x) production coincided with O(2) concentrations of 103-116 microM and pH value of 5.2. Together, molecular and microsensor data indicate that Crenarchaeota could oxidize ammonia to nitrite aerobically, and thus be involved in nitrification inside the ascidian tissue.

  18. Distribution and Localised Effects of the Invasive Ascidian Didemnum perlucidum (Monniot 1983) in an Urban Estuary.

    PubMed

    Simpson, Tiffany Schenk; Wernberg, Thomas; McDonald, Justin I

    2016-01-01

    Didemnid ascidians are notorious marine invaders, fouling infrastructure in many ecosystems globally. However, there have been few reports of direct interactions with native species in their natural environment. The invasive colonial ascidian Didemnum perlucidum was discovered in the Swan River estuary (Western Australia) growing on the native seagrass Halophila ovalis. Given the known effects of other related Didemnum species it was expected that D. perlucidum could adversely affect the seagrass, with possible flow on effects to the rest of the ecosystem. This study aimed to document the distribution and abundance of D. perlucidum in the estuary, and to determine whether this species had a negative impact on H. ovalis or associated flora and fauna. D. perlucidum was largely present near areas of infrastructure, particularly mooring buoys, suggesting these were the source of D. perlucidum recruits on the seagrasses. It showed a clear seasonal pattern in abundance, with highly variable cover and colony size. D. perlucidum had a measurable effect on H. ovalis, with colonies enveloping all plant tissue, likely restricting the photosynthetic ability of individual leaves and total plant biomass. There were also significantly less seagrass-associated mud snails (Batillaria australis) where D. perlucidum cover was high. These results demonstrate the ability of invasive ascidians to colonise and affect native seagrasses and associated biota. Seagrasses are pivotal to the ecological function of many urban estuaries world-wide. Biodiversity in these systems is already vulnerable to multiple stressors from human activities but the potential stress of fouling ascidians may pose an additional and increasing threat in the future.

  19. Cloning of ascidian homeobox genes provides evidence for a primordial chordate cluster.

    PubMed

    Di Gregorio, A; Spagnuolo, A; Ristoratore, F; Pischetola, M; Aniello, F; Branno, M; Cariello, L; Di Lauro, R

    1995-04-24

    In order to isolate genes important in controlling embryonic development in Tunicates, a genomic library from the ascidian Ciona intestinalis was screened with a degenerate oligodeoxyribonucleotide encoding the third helix of Antennapedia-type homeoboxes. Fourteen C. intestinalis homeobox genes, corresponding to several classes of homeodomains, have been identified. Five of the isolated homeoboxes show their highest homology to members of the Vertebrate HOX clusters. mRNAs for two of the isolated homeoboxes are present in unfertilized C. intestinalis eggs.

  20. Distribution and Localised Effects of the Invasive Ascidian Didemnum perlucidum (Monniot 1983) in an Urban Estuary

    PubMed Central

    Wernberg, Thomas; McDonald, Justin I.

    2016-01-01

    Didemnid ascidians are notorious marine invaders, fouling infrastructure in many ecosystems globally. However, there have been few reports of direct interactions with native species in their natural environment. The invasive colonial ascidian Didemnum perlucidum was discovered in the Swan River estuary (Western Australia) growing on the native seagrass Halophila ovalis. Given the known effects of other related Didemnum species it was expected that D. perlucidum could adversely affect the seagrass, with possible flow on effects to the rest of the ecosystem. This study aimed to document the distribution and abundance of D. perlucidum in the estuary, and to determine whether this species had a negative impact on H. ovalis or associated flora and fauna. D. perlucidum was largely present near areas of infrastructure, particularly mooring buoys, suggesting these were the source of D. perlucidum recruits on the seagrasses. It showed a clear seasonal pattern in abundance, with highly variable cover and colony size. D. perlucidum had a measurable effect on H. ovalis, with colonies enveloping all plant tissue, likely restricting the photosynthetic ability of individual leaves and total plant biomass. There were also significantly less seagrass-associated mud snails (Batillaria australis) where D. perlucidum cover was high. These results demonstrate the ability of invasive ascidians to colonise and affect native seagrasses and associated biota. Seagrasses are pivotal to the ecological function of many urban estuaries world-wide. Biodiversity in these systems is already vulnerable to multiple stressors from human activities but the potential stress of fouling ascidians may pose an additional and increasing threat in the future. PMID:27144600

  1. Cockles, barnacles and ascidians compose a subtidal facilitation cascade with multiple hierarchical levels of foundation species.

    PubMed

    Yakovis, Eugeniy; Artemieva, Anna

    2017-03-22

    Facilitation cascades occur when multiple foundation species in a community are involved in a hierarchy of positive interactions, and consist of a primary facilitator which positively affects secondary facilitators, each supporting a suit of dependent species. There is no theoretical limit to the number of levels in a facilitation cascade, yet the existence of more than two has rarely been examined. We manipulated biogenic substrate produced by a primary facilitator (cockle shells) and a secondary facilitator (barnacles and their empty tests) in a space-limited subtidal community to test the hypothesis that solitary ascidians would be the third-level facilitator. In the field, most ascidians were found on barnacles, and most barnacles occupied cockle shells. To produce this pattern, barnacles could nurse ascidians (a longer 'facilitation chain') or outcompete them from cockle shells (a shorter chain). Experimental results clearly supported the nursing hypothesis providing evidence for a facilitation cascade with three hierarchical levels of foundation species. Our findings confirm that like predation and competition, positive interspecific interactions nest into multi-tier hierarchies with numerous levels. While the number of foundation species should increase community stability and resilience as it increases diversity and reduces environmental stress, facilitation chain length may have the opposite effect.

  2. Spermiotoxicity of nickel nanoparticles in the marine invertebrate Ciona intestinalis (ascidians)

    PubMed Central

    Gallo, Alessandra; Boni, Raffaele; Buttino, Isabella; Tosti, Elisabetta

    2016-01-01

    Abstract Nickel nanoparticles (Ni NPs) are increasingly used in modern industries as catalysts, sensors, and in electronic applications. Due to this large use, their inputs into marine environment have significantly increased; however, the potential ecotoxicological effects in marine environment have so far received little attention. In particular, little is known on the impact of NPs on gamete quality of marine organisms and on the consequences on fertility potential. The present study examines, for the first time, the impact of Ni NPs exposure on sperm quality of the marine invertebrate Ciona intestinalis (ascidian). Several parameters related with sperm status such as plasma membrane lipid peroxidation, mitochondrial membrane potential (MMP), intracellular pH, DNA integrity, and fertilizing ability were assessed as toxicity end points after exposure to different Ni NPs concentrations. Ni NPs generate oxidative stress that in turn induces lipid peroxidation and DNA fragmentation, and alters MMP and sperm morphology. Furthermore, sperm exposure to Ni NPs affects their fertilizing ability and causes developmental anomalies in the offspring. All together, these results reveal a spermiotoxicity of Ni NPs in ascidians suggesting that the application of these NPs should be carefully assessed as to their potential toxic effects on the health of marine organisms that, in turn, may influence the ecological system. This study shows that ascidian sperm represent a suitable and sensitive tool for the investigation of the toxicity of NPs entered into marine environment, for defining the mechanisms of toxic action and for the environmental monitoring purpose. PMID:27080039

  3. Gut-spilling in chordates: Evisceration in the tropical ascidian Polycarpa mytiligera

    PubMed Central

    Shenkar, Noa; Gordon, Tal

    2015-01-01

    The ejection of internal organs, i.e., evisceration, is a well-known phenomenon in sea-cucumbers. We report the ability of a member of the Chordate phyla, the tropical ascidian Polycarpa mytiligera, to eviscerate and regenerate its gut within 12 days, and to rebuild its branchial sac within 19 days. Evisceration occurred within 4–43 seconds of gentle mechanical pressure exerted on the tunic in 47% of the tested P. mytiligera. Individuals were able to discard up to 3/4 of their digestive tract via the incurrent siphon by rupture of the branchial sac in this area. Although chemical analysis revealed no significant levels of toxic compounds, the eviscerated guts were unpalatable to the triggerfish and pufferfish on which they were tested, suggesting evisceration as a defense mechanism. Given the close affinity of ascidians to vertebrates, the regeneration pathway of the viscera and branchial sac of ascidians suggests its potential beneficial application in soft tissue regeneration research. PMID:25880620

  4. PSP toxins profile in ascidian Microcosmus vulgaris (Heller, 1877) after human poisoning in Croatia (Adriatic Sea).

    PubMed

    Roje-Busatto, Romana; Ujević, Ivana

    2014-03-01

    Toxins known to cause Paralytic Shellfish Poisoning (PSP) syndrome in humans that can have serious economic consequences for aquaculture were determined in ascidians of the genus Microcosmus. Significant concentrations of toxins were confirmed in all tested samples collected from the western coast of Istria Peninsula (Adriatic Sea, Croatia) when six people were poisoned following the consumption of fresh ascidians. Several species of bivalves that were under continuous monitoring had not accumulated PSP toxins although they were exposed to the same environmental conditions over the survey period. In the present study, HPLC-FLD with pre-column oxidation of PSP toxins has been carried out to provide evidence for the first human intoxication due to consumption of PSP toxic ascidians (Microcosmus vulgaris, Heller, 1877) harvested from the Adriatic Sea. Qualitative analysis established the presence of six PSP toxins: saxitoxin (STX), decarbamoylsaxitoxin (dcSTX), gonyautoxins 2 and 3 (GTX2,3), decarbamoylgonyautoxins 2 and 3 (dcGTX2,3), gonyautoxin 5 (GTX5) and N-sulfocarbamoylgonyautoxins 1 and 2 (C1,2), while quantitative analysis suggested STX and GTX2,3 as dominant toxin types and the ones that contribute the most to the overall toxicity of these samples with concentrations near the regulatory limit.

  5. Analysis of the Transcription Regulatory Mechanism of Otx During the Development of the Sensory Vesicle in Ciona intestinalis.

    PubMed

    Oonuma, Kouhei; Hirose, Dan; Takatori, Naohito; Saiga, Hidetoshi

    2014-09-01

    Establishment of the anterior-posterior axis is an important event in the development of bilateral animals. A homeodomain transcription factor, Otx, is important for the formation of the anterior part of the embryo, and its mRNA is expressed in a continuous manner in a wide range of animals. This pattern of expression is thought to be important for the formation of anterior neural structures, but the mechanism that regulates Otx expression remains largely unknown. Towards understanding how the transcription of Otx is maintained in the cells of anterior neural structure, the sensory vesicle, during embryogenesis, we examined transcription regulatory mechanisms of Otx, using embryos of the ascidian, Ciona intestinalis, from the gastrula to tailbud stages, which have not been studied previously. We identified two genomic regions capable of mimicking the Otx expression pattern from the gastrula to tailbud stages. Putative transcription factor binding sites required for this activity were identified. Notably, distinct sets of transcription factor binding sites were required at different developmental stages for the expression of Otx, suggesting that the continuity of Otx is supported by distinct transcriptional mechanisms in the gastrula and neurula stages. Along with previous studies using Halocynthia roretzi, the present results provide insight into the evolution of transcriptional regulatory mechanism of Otx.

  6. In vitro acylation of okadaic acid in the presence of various bivalves' extracts.

    PubMed

    Konoki, Keiichi; Onoda, Tatsuya; Watanabe, Ryuichi; Cho, Yuko; Kaga, Shinnosuke; Suzuki, Toshiyuki; Yotsu-Yamashita, Mari

    2013-01-29

    The dinoflagellate Dinophysis spp. is responsible for diarrhetic shellfish poisoning (DSP). In the bivalves exposed to the toxic bloom of the dinoflagellate, dinophysistoxin 3 (DTX3), the 7-OH acylated form of either okadaic acid (OA) or DTX1, is produced. We demonstrated in vitro acylation of OA with palmitoyl CoA in the presence of protein extract from the digestive gland, but not other tissues of the bivalve Mizuhopecten yessoensis. The yield of 7-O-palmitoyl OA reached its maximum within 2 h, was the highest at 37 °C followed by 28 °C, 16 °C and 4 °C and was the highest at pH 8 in comparison with the yields at pH 6 and pH 4. The transformation also proceeded when the protein extract was prepared from the bivalves Corbicula japonica and Crassostrea gigas. The OA binding protein OABP2 identified in the sponge Halichondria okadai was not detected in the bivalve M. yessoensis, the bivalve Mytilus galloprovincialis and the ascidian Halocynthia roretzi, though they are known to accumulate diarrhetic shellfish poisoning toxins. Since DTX3 does not bind to protein phosphatases 1 and 2A, the physiological target for OA and DTXs in mammalian cells, the acylation of DSP toxins would be related to a detoxification mechanism for the bivalve species.

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

    PubMed

    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

  8. Nitric Oxide Acts as a Positive Regulator to Induce Metamorphosis of the Ascidian Herdmania momus

    PubMed Central

    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

  9. Ascidian Mitogenomics: Comparison of Evolutionary Rates in Closely Related Taxa Provides Evidence of Ongoing Speciation Events

    PubMed Central

    Griggio, Francesca; Voskoboynik, Ayelet; Iannelli, Fabio; Justy, Fabienne; Tilak, Marie-Ka; Xavier, Turon; Pesole, Graziano; Douzery, Emmanuel J.P.; Mastrototaro, Francesco; Gissi, Carmela

    2014-01-01

    Ascidians are a fascinating group of filter-feeding marine chordates characterized by rapid evolution of both sequences and structure of their nuclear and mitochondrial genomes. Moreover, they include several model organisms used to investigate complex biological processes in chordates. To study the evolutionary dynamics of ascidians at short phylogenetic distances, we sequenced 13 new mitogenomes and analyzed them, together with 15 other available mitogenomes, using a novel approach involving detailed whole-mitogenome comparisons of conspecific and congeneric pairs. The evolutionary rate was quite homogeneous at both intraspecific and congeneric level, and the lowest congeneric rates were found in cryptic (morphologically undistinguishable) and in morphologically very similar species pairs. Moreover, congeneric nonsynonymous rates (dN) were up to two orders of magnitude higher than in intraspecies pairs. Overall, a clear-cut gap sets apart conspecific from congeneric pairs. These evolutionary peculiarities allowed easily identifying an extraordinary intraspecific variability in the model ascidian Botryllus schlosseri, where most pairs show a dN value between that observed at intraspecies and congeneric level, yet consistently lower than that of the Ciona intestinalis cryptic species pair. These data suggest ongoing speciation events producing genetically distinct B. schlosseri entities. Remarkably, these ongoing speciation events were undetectable by the cox1 barcode fragment, demonstrating that, at low phylogenetic distances, the whole mitogenome has a higher resolving power than cox1. Our study shows that whole-mitogenome comparative analyses, performed on a suitable sample of congeneric and intraspecies pairs, may allow detecting not only cryptic species but also ongoing speciation events. PMID:24572017

  10. The alien ascidian Styela clava now invading the Sea of Marmara (Tunicata: Ascidiacea)

    PubMed Central

    Çinar, Melih Ertan

    2016-01-01

    Abstract During the implementation of a large project aimed to investigate the benthic community structures of the Sea of Marmara, specimens of the invasive ascidian species Styela clava were collected on natural substrata (rocks) at 10 m depth at one locality (Karamürsel) in İzmit Bay. The specimens were mature, containing gametes, indicating that the species had become established in the area. The Sea of Marmara seems to provide suitable conditions for this species to survive and form proliferating populations. PMID:27047235

  11. Population dynamics of the solitary ascidian Herdmania momus (Savignyi, 1816) in Jeju Island, Korea

    NASA Astrophysics Data System (ADS)

    Yi, Chang Ho; Kim, Jeong Ha

    2016-09-01

    In 2007-2008, a population outbreak of the solitary ascidian Herdmania momus was observed along the coasts of Jeju Island and the ascidians became the top dominant species in macrobenthic communities. We conducted field experiments on population dynamics and demographic parameters including seasonal density fluctuation, vertical distribution, recruitment patterns, mortality, and growth rate. Recruitment continued year-round except in April following the lowest water temperature season in February. Population density was highest in August-October, concomitantly with the peak in recruitment, related to the highest water temperature. The lowest density was observed in February-April when the water temperature was lowest. In April all individuals disappeared from all permanent plots, resulting in a maximum life span of 10-12 months. Individuals of newly recruited H. momus grew to have an adult size of 4-6 cm in only 3-4 months. Higher densities were observed in the shallower areas (5 m) compared to the deeper zones. More recruitment occurred on vertical slopes than horizontal substrates, but substrate pre-occupancy caused no difference in recruitment. This is the first report on H. momus population-level investigation in Korea, which provides valuable baseline information on the current status of population demography and their potential community-level influence on Jeju coasts.

  12. The recently-described ascidian species Molgula tectiformis is a direct developer.

    PubMed

    Tagawa, K; Jeffery, W R; Satoh, N

    1997-04-01

    Molgula tectiformis is a new ascidian species recently described by Nishikawa (1991). In Otsuchi Bay, Iwate, Japan, they are easily obtainable from cages for culturing scallops. We report here that M. tectiformis is another example of a direct developer: their embryonic development is lacking the tadpole larva. The fertilized egg is orange and about 150 microns in diameter. At 18 degrees C, the egg cleaves at about 20 min intervals and gastrulation occurs about 5 hr after fertilization. In contrast to conventionally-developing ascidians, M. tectiformis does not form a tadpole larva. Immediately before hatching, three stolons or ampullae begin to extend from the tailless embryo. After hatching the stolons mediate the attachment of the juvenile body to the substratum. Histochemistry for tissue-specific enzyme activity did not detect muscle-specific acetyl-cholinesterase, endoderm-specific alkaline phosphatase, and pigment cell-specific tyrosinase. In addition, in situ hybridization could not prove the presence of muscle actin gene transcripts in the embryo. These results suggest that these larval tissues do not differentiate in M. tectiformis embryos. Because M. tectiformis is common and gravid year-around in Otsuchi Bay, this direct developer provides the opportunity for further analysis of molecular changes during evolution that cause an alternative mode of development.

  13. Differentiation of papillae and rostral sensory neurons in the larva of the ascidian Botryllus schlosseri (Tunicata).

    PubMed

    Caicci, Federico; Zaniolo, Giovanna; Burighel, Paolo; Degasperi, Valentina; Gasparini, Fabio; Manni, Lucia

    2010-02-15

    During the metamorphosis of tunicate ascidians, the swimming larva uses its three anterior papillae to detect the substrate for settlement, reabsorbs its chordate-like tail, and becomes a sessile oozooid. In view of the crucial role played by the anterior structures and their nerve relations, we applied electron microscopy and immunocytochemistry to study the larva of the colonial ascidian Botryllus schlosseri, following differentiation of the anterior epidermis during late embryogenesis, the larval stage, and the onset of metamorphosis. Rudiments of the papillae appear in the early tail-bud stage as ectodermic protrusions, the apexes of which differentiate into central and peripheral bipolar neurons. Axons fasciculate into two nerves direct to the brain. Distally, the long, rod-like dendritic terminations extend during the larval stage, becoming exposed to sea water. After the larva selects and adheres to the substrate, these neurons retract and regress. Adjacent to the papillae, other scattered neurons insinuate dendrites into the tunic and form the net of rostral trunk epidermal neurons (RTENs) which fasciculate together with the papillary neurons. Our data indicate that the papillae are simple and coniform, the papillary neurons are mechanoreceptors, and the RTENs are chemoreceptors. The interpapillary epidermal area, by means of an apocrine secretion, provides sticky material for temporary adhesion of the larva to the substrate.

  14. Evolution and development of budding by stem cells: ascidian coloniality as a case study.

    PubMed

    Brown, Federico D; Swalla, Billie J

    2012-09-15

    The evolution of budding in metazoans is not well understood on a mechanistic level, but is an important developmental process. We examine the evolution of coloniality in ascidians, contrasting the life histories of solitary and colonial forms with a focus on the cellular and developmental basis of the evolution of budding. Tunicates are an excellent group to study colonial transitions, as all solitary larvae develop with determinant and invariant cleavage patterns, but colonial species show robust developmental flexibility during larval development. We propose that acquiring new stem cell lineages in the larvae may be a preadaptation necessary for the evolution of budding. Brooding in colonial ascidians allows increased egg size, which in turn allows greater flexibility in the specification of cells and cell numbers in late embryonic and pre-metamorphic larval stages. We review hypotheses for changes in stem cell lineages in colonial species, describe what the current data suggest about the evolution of budding, and discuss where we believe further studies will be most fruitful.

  15. Origin and Dispersal History of Two Colonial Ascidian Clades in the Botryllus schlosseri Species Complex

    PubMed Central

    Nydam, Marie L.

    2017-01-01

    Human-induced global warming and species introductions are rapidly altering the composition and functioning of Earth’s marine ecosystems. Ascidians (Phylum Chordata, Subphylum Tunicata, Class Ascidiacea) are likely to play an increasingly greater role in marine communities. The colonial ascidian B. schlosseri is a cryptic species complex comprising five genetically divergent clades (A-E). Clade A is a global species, and Clade E has so far been identified in European waters only. Using the largest mitochondrial cytochrome oxidase I datasets yet assembled, we determine the origin and dispersal history of these species. Nucleotide diversity and Approximate Bayesian Computation analyses support a Pacific origin for Clade A, with two likely dispersal scenarios that both show the northwestern Atlantic populations establishing early in the history of the species. Both Discrete Phylogeographic Analysis and Approximate Bayesian Computation support an origin of Clade E on the French side of the English Channel. An unsampled lineage evolved from the French lineage, which reflects the conclusion from the median joining network that not all Clade E lineages have been sampled. This unsampled lineage gave rise to the haplotypes on the English side of the English Channel, which were the ancestors to the Mediterranean and Bay of Biscay populations. Clade E has a wider geographic range than previously thought, and shows evidence of recent range expansion. Both Clade A and Clade E should be considered widespread species: Clade A globally and Clade E within Europe. PMID:28107476

  16. Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity

    PubMed Central

    2011-01-01

    Background Previously, we have reported the presence of highly sulfated dermatans in solitary ascidians from the orders Phlebobranchia (Phallusia nigra) and Stolidobranchia (Halocynthia pyriformis and Styela plicata). Despite the identical disaccharide backbone, consisting of [→4IdoA(2S)β-1→3GalNAcβ-1→], those polymers differ in the position of sulfation on the N-Acetyl galactosamine, which can occur at carbon 4 or 6. We have shown that position rather than degree of sulfation is important for heparin cofactor II activity. As a consequence, 2,4- and 2,6-sulfated dermatans have high and low heparin cofactor II activities, respectively. In the present study we extended the disaccharide analysis of ascidian dermatan sulfates to additional species of the orders Stolidobranchia (Herdmania pallida, Halocynthia roretzi) and Phlebobranchia (Ciona intestinalis), aiming to investigate how sulfation evolved within Tunicata. In addition, we analysed how heparin cofactor II activity responds to dermatan sulfates containing different proportions of 2,6- or 2,4-disulfated units. Results Disaccharide analyses indicated a high content of disulfated disaccharide units in the dermatan sulfates from both orders. However, the degree of sulfation decreased from Stolidobranchia to Phlebobranchia. While 76% of the disaccharide units in dermatan sulfates from stolidobranch ascidians are disulfated, 53% of disulfated disaccharides are found in dermatan sulfates from phlebobranch ascidians. Besides this notable difference in the sulfation degree, dermatan sulfates from phlebobranch ascidians contain mainly 2,6-sulfated disaccharides whereas dermatan sulfate from the stolidobranch ascidians contain mostly 2,4-sulfated disaccharides, suggesting that the biosynthesis of dermatan sulfates might be differently regulated during tunicates evolution. Changes in the position of sulfation on N-acetylgalactosamine in the disaccharide [→4IdoA(2-Sulfate)β-1→3GalNAcβ-1→] modulate heparin

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

    PubMed

    Hebras, Celine; McDougall, Alex

    2012-01-01

    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 in eggs and

  18. CRISPR/Cas9-mediated gene knockout in the ascidian Ciona intestinalis.

    PubMed

    Sasaki, Haruka; Yoshida, Keita; Hozumi, Akiko; Sasakura, Yasunori

    2014-09-01

    Knockout of genes with CRISPR/Cas9 is a newly emerged approach to investigate functions of genes in various organisms. We demonstrate that CRISPR/Cas9 can mutate endogenous genes of the ascidian Ciona intestinalis, a splendid model for elucidating molecular mechanisms for constructing the chordate body plan. Short guide RNA (sgRNA) and Cas9 mRNA, when they are expressed in Ciona embryos by means of microinjection or electroporation of their expression vectors, introduced mutations in the target genes. The specificity of target choice by sgRNA is relatively high compared to the reports from some other organisms, and a single nucleotide mutation at the sgRNA dramatically reduced mutation efficiency at the on-target site. CRISPR/Cas9-mediated mutagenesis will be a powerful method to study gene functions in Ciona along with another genome editing approach using TALE nucleases.

  19. Germ cell mutations of the ascidian Ciona intestinalis with TALE nucleases.

    PubMed

    Yoshida, Keita; Treen, Nicholas; Hozumi, Akiko; Sakuma, Tetsushi; Yamamoto, Takashi; Sasakura, Yasunori

    2014-05-01

    Targeted mutagenesis of genes-of-interest, or gene-knockout, is a powerful method to address the functions of genes. Engineered nucleases have enabled this approach in various organisms because of their ease of use. The ascidian Ciona intestinalis is an excellent organism to analyze gene functions by means of genetic technologies. In our previous study, we reported mutagenesis of Ciona somatic cells with TALE nucleases (TALENs) by electroporating expression constructs. In this study, we report germ cell mutagenesis of Ciona by microinjecting mRNAs encoding TALENs. TALEN mRNAs introduced mutations to target genes in both somatic and germ cells. TALEN-mediated mutations in the germ cell genome were inherited by the next generation. We conclude that knockout lines of Ciona that have disrupted target genes can be established through TALEN-mediated germ cell mutagenesis.

  20. Transposon-mediated targeted and specific knockdown of maternally expressed transcripts in the ascidian Ciona intestinalis.

    PubMed

    Iitsuka, Takako; Mita, Kaoru; Hozumi, Akiko; Hamada, Mayuko; Satoh, Nori; Sasakura, Yasunori

    2014-05-23

    Maternal mRNAs play crucial roles during early embryogenesis of ascidians, but their functions are largely unknown. In this study, we developed a new method to specifically knockdown maternal mRNAs in Ciona intestinalis using transposon-mediated transgenesis. We found that GFP expression is epigenetically silenced in Ciona intestinalis oocytes and eggs, and this epigenetic silencing of GFP was used to develop the knockdown method. When the 5' upstream promoter and 5' untranslated region (UTR) of a maternal gene are used to drive GFP in eggs, the maternal gene is specifically knocked down together with GFP. The 5' UTR of the maternal gene is the major element that determines the target gene silencing. Zygotic transcription of the target gene is unaffected, suggesting that the observed phenotypes specifically reflect the maternal function of the gene. This new method can provide breakthroughs in studying the functions of maternal mRNAs.

  1. [Distribution and abundance of the ascidian Ecteinascidia turbinata (Ascidiacea: Perophoridae) in Cuba].

    PubMed

    Hernández-Zanuy, Aida; Carballo, José Luis; García-Cagide, Alida; Naranjo, Santiago; Esquivel, Macario

    2007-03-01

    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 Rio 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/m.

  2. Ultrastructures and classification of circulating hemocytes in 9 botryllid ascidians (chordata: ascidiacea).

    PubMed

    Hirose, Euichi; Shirae, Maki; Saito, Yasunori

    2003-05-01

    Ultrastructures of circulating hemocytes were studied in 9 botryllid ascidians. The hemocytes are classified into five types: hemoblasts, phagocytes, granulocytes, morula cells, and pigment cells. These five types are always found in the 9 species. They should represent the major hemocyte types of the circulating cells in the blood. Hemoblasts are small hemocytes having a high nucleus/cytoplasm ratio. There are few granular or vacuolar inclusions in the cytoplasm. Phagocytes have phagocytic activity and their shape is variable depending on the amount of engulfed materials. In granulocytes, shape and size of granules are different among the species. Morula cells are characterized by several vacuoles filled with electron dense materials. In pigment cells, the bulk of the cytoplasm is occupied by one or a few vacuoles containing pigment granules. We also described some other hemocyte types found in particular species. Furthermore, we encountered free oocytes circulating in the blood in two species, Botryllus primigenus and Botrylloides lentus.

  3. Experimental allometry: effect of size manipulation on metabolic rate of colonial ascidians

    PubMed Central

    Nakaya, Fumio; Saito, Yasunori; Motokawa, Tatsuo

    2005-01-01

    The allometric scaling of metabolic rate of organisms, the three-quarters power rule, has led to a questioning of the basis for the relation. We attacked this problem experimentally for the first time by employing the modular organism, the ascidian that forms a single layered flat colony, as a model system. The metabolic rate and colony size followed the three-quarters power relation, which held even after the colony size was experimentally manipulated. Our results established that the three-quarters power relation is a real continuous function, not an imaginary statistical regression. The fact that all the hypotheses failed to explain why the two-dimensional organism adhered to the three-quarters power relation led us to propose a new hypothesis, in which the allometric relation derives from the self-organized criticality based on local interaction between modulus-comprising organisms. PMID:16191604

  4. Regeneration of oral siphon pigment organs in the ascidian Ciona intestinalis

    PubMed Central

    Auger, Hélène; Sasakura, Yasunori; Joly, Jean-Stéphane; Jeffery, William R.

    2013-01-01

    Ascidians have powerful capacities for regeneration but the underlying mechanisms are poorly understood. Here we examine oral siphon regeneration in the solitary ascidian Ciona intestinalis. Following amputation, the oral siphon rapidly reforms oral pigment organs (OPO) at its distal margin prior to slower regeneration of proximal siphon parts. The early stages of oral siphon reformation include cell proliferation and re-growth of the siphon nerves, although the neural complex (adult brain and associated organs) is not required for regeneration. Young animals reform OPO more rapidly after amputation than old animals indicating that regeneration is age dependent. UV irradiation, microcautery, and cultured siphon explant experiments indicate that OPOs are replaced as independent units based on local differentiation of progenitor cells within the siphon, rather than by cell migration from a distant source in the body. The typical pattern of eight OPOs and siphon lobes is restored with fidelity after distal amputation of the oral siphon, but as many as 16 OPOs and lobes can be reformed following proximal amputation near the siphon base. Thus, the pattern of OPO regeneration is determined by cues positioned along the proximal distal axis of the oral siphon. A model is presented in which columns of siphon tissue along the proximal–distal axis below pre-existing OPO are responsible for reproducing the normal OPO pattern during regeneration. This study reveals previously unknown principles of oral siphon and OPO regeneration that will be important for developing Ciona as a regeneration model in urochordates, which may be the closest living relatives of vertebrates. PMID:20059994

  5. Molecular and morphological discrimination between an invasive ascidian, Ascidiella aspersa, and its congener A. scabra (Urochordata: Ascidiacea).

    PubMed

    Nishikawa, Teruaki; Oohara, Ichiro; Saitoh, Kenji; Shigenobu, Yuya; Hasegawa, Natsuki; Kanamori, Makoto; Baba, Katsuhisa; Turon, Xavier; Bishop, John D D

    2014-03-01

    The solitary ascidian Ascidiella aspersa (Müller, 1776) has sometimes been regarded as conspecific with A. scabra (Müller, 1776), although previous detailed morphological comparisons have indicated that the two are distinguishable by internal structures. Resolution of this taxonomic issue is important because A. aspersa has been known as a notoriously invasive ascidian, doing much damage to aquaculture e.g. in Hokkaido, Japan. We collected many specimens from European waters (including the Swedish coast, near the type localities of these two species) and Hokkaido, Japan (as an alien population) and made molecular phylogenetic analyses using the mitochondrial cytochrome c oxidase subunit I (COI) gene, and found that in terms of COI sequences all the analyzed specimens were clustered into two distinct groups, one of which is morphologically referable to A. aspersa and the other to A. scabra. Thus, these two species should be regarded as distinct from each other.

  6. Microenvironmental Ecology of the Chlorophyll b-Containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella

    PubMed Central

    Kühl, Michael; Behrendt, Lars; Trampe, Erik; Qvortrup, Klaus; Schreiber, Ulrich; Borisov, Sergey M.; Klimant, Ingo; Larkum, Anthony W. D.

    2012-01-01

    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 minutes of darkness, while the same zone exhibited O2 super-saturation and strongly alkaline pH after a few minutes 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. PMID:23226144

  7. Ordered expression pattern of Hox and ParaHox genes along the alimentary canal in the ascidian juvenile.

    PubMed

    Nakayama, Satoshi; Satou, Kunihiro; Orito, Wataru; Ogasawara, Michio

    2016-07-01

    The Hox and ParaHox genes of bilateria share a similar expression pattern along the body axis and are known to be associated with anterior-posterior patterning. In vertebrates, the Hox genes are also expressed in presomitic mesoderm and gut endoderm and the ParaHox genes show a restricted expression pattern in the gut-related derivatives. Regional expression patterns in the embryonic central nervous system of the basal chordates amphioxus and ascidian have been reported; however, little is known about their endodermal expression in the alimentary canal. We focus on the Hox and ParaHox genes in the ascidian Ciona intestinalis and investigate the gene expression patterns in the juvenile, which shows morphological regionality in the alimentary canal. Gene expression analyses by using whole-mount in situ hybridization reveal that all Hox genes have a regional expression pattern along the alimentary canal. Expression of Hox1 to Hox4 is restricted to the posterior region of pharyngeal derivatives. Hox5 to Hox13 show an ordered expression pattern correlated with each Hox gene number along the postpharyngeal digestive tract. This expression pattern along the anterior-posterior axis has also been observed in Ciona ParaHox genes. Our observations suggest that ascidian Hox and ParaHox clusters are dispersed; however, the ordered expression patterns along the alimentary canal appear to be conserved among chordates.

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

    PubMed

    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

  9. Ecological observations on the colonial ascidian Didemnum sp. in a New England tide pool habitat

    USGS Publications Warehouse

    Valentine, P.C.; Carman, M.R.; Blackwood, D.S.; Heffron, E.J.

    2007-01-01

    The colonial ascidian Didemnum sp. has colonized northwestern Atlantic coastal habitats from southern Long Island, New York, to Eastport, Maine. It is also present in offshore habitats of the Georges Bank fishing grounds. It threatens to alter fisheries habitats and shellfish aquacultures. Observations in a tide pool at Sandwich, MA from December 2003 to February 2006 show that Didemnum sp. tolerates water temperatures ranging from ≤ 1 to > 24 °C, with daily changes of up to 11 °C. It attaches to pebbles, cobbles, and boulders, and it overgrows other tunicates, seaweeds, sponges, and bivalves. From May to mid July, colonies appear as small patches on the bottoms of rocks. Colonies grow rapidly from July to September, with some growth into December, and they range in color from pink to pale yellow to pale orange. Colony health declines from October through April, presumably in response to changes in water temperatures, and this degenerative process is manifested by color changes, by the appearance of small dark brown spots that represent clumps of fecal pellets in the colony, by scavenging by periwinkles, and by a peeling-away of colonies from the sides of cobbles and boulders. At Sandwich, colonies died that were exposed to air at low tide. The species does not exhibit this seasonal cycle of growth and decline in subtidal habitats (40–65 m) on the Georges Bank fishing grounds where the daily climate is relatively stable and annual water temperatures range from 4 to 15 °C. Experiments in the tide pool with small colony fragments (5 to 9 cm2) show they re-attach and grow rapidly by asexual budding, increasing in size 6- to 11-fold in the first 15 days. Didemnum sp. at Sandwich has no known predators except for common periwinkles (Littorina littorea) that graze on degenerating colonies in the October to April time period and whenever colonies are stressed by desiccation. The tendencies of the ascidian (1) to attach to firm substrates, (2) to rapidly overgrow

  10. Fertilization in an egg-brooding colonial ascidian does not vary with population density.

    PubMed

    Phillippi, Aimee; Hamann, Ellen; Yund, Philip O

    2004-06-01

    The possibility that free-spawning marine organisms may be subject to fertilization failure at low population density (due to the effects of sperm dilution) has sparked much interest, but these effects have been demonstrated only in a few species that broadcast their eggs. Some egg-brooding species may overcome dilution effects by filtering low concentrations of sperm from seawater and fertilizing eggs throughout an extended period of time. We examined the effects of population density and size on fertilization in Botryllus schlosseri, a hermaphroditic colonial ascidian that free-spawns sperm, but broods eggs. We experimentally manipulated the size and density of mating groups and surveyed fertilization levels in natural populations that varied in density. Fertilization was not affected by variation in population size or density in either the experimental or natural populations. Near the end of the reproductive season, some eggs may have been fertilized too late to complete development, suggesting a temporal form of sperm limitation that has not been considered in other systems. We also detected greater variability in fertilization levels at lower population density. Nevertheless, these results suggest that caution must be used in extrapolating reported density effects on fertilization to all taxa of free-spawners; density effects may be reduced in brooders that have efficient sperm collection mechanisms.

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

    PubMed

    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.

  12. Filter-feeding ascidians ( Ciona intestinalis) in a shallow cove: Implications of hydrodynamics for grazing impact

    NASA Astrophysics Data System (ADS)

    Riisgård, Hans Ulrik; Jürgensen, Carsten; Clausen, Torben

    1996-06-01

    The grazing impact by a dense population of filter-feeding ascidians Ciona intestinalis on horizontally flowing water (driven by density circulation) in a shallow cove (Kertinge Nor, Denmark) has been described and quantified by means of a simple one-dimensional numerical model. The agreement between observations and modelled predictions was satisfactory. The applied numerical model has the following analytical solution in the idealized case: Cx = C0e -( fx/ Y2) , where Cx = algal concentration at a downstream distance x, C0 = initial concentration, f = F/ vc; F = area specific population filtration rate; vc = current velocity; Y 2 = depth of mixed layer below halocline. The numerical model quantifies the actual grazing impact while the analytical model illustrates the governing physics in well-known terms. To describe situations with no current ( i.e. stagnant water), we performed simulation studies in the laboratory and measured vertical profiles of algal cells over filter-feeding C. intestinalis. The results showed that phytoplankton became reduced in a near-bottom water layer of 20-30 cm thickness. Such water layers may develop in stagnant water (calm days and no advective currents), thus uncoupling the pelagic food and the filter feeders which within a short time will experience extremely meagre food conditions.

  13. Siphon regeneration capacity is compromised during aging in the ascidian Ciona intestinalis.

    PubMed

    Jeffery, William R

    2012-01-01

    The ascidian Ciona intestinalis has a short life span and powerful regeneration capacities. The regeneration of the oral siphon (OS) involves wound healing, blastema formation, cell proliferation, and replacement of 8 oral pigment organs (OPO), the latter via differentiation and migration of stem/precursor cells from localized niches in the siphon. The restoration of OPO pattern during OS regeneration occurs with a high degree of accuracy through three successive cycles of amputation. It is shown here that oral siphons of the largest and oldest members of a wild Ciona population do not completely regenerate their siphons after amputation. The loss of regeneration capacity was accompanied by reduced cell proliferation. In contrast to arrested OS outgrowth, the stem/precursor cells responsible for OPO replacement "over-differentiate" after OS amputation in the oldest animals, the typical number of OPO is increased from 8 to 12-16, and malformed OPO are produced. Also in contrast to younger animals, the oldest animals of the population show arrested OPO development after two consecutive cycles of amputation and regeneration. We conclude that there is a size and age threshold in Ciona after which the regenerative capacity of the OS is compromised due to effects of aging on cell proliferation.

  14. Establishment of enhancer detection lines expressing GFP in the gut of the ascidian Ciona intestinalis.

    PubMed

    Yoshida, Reiko; Sasakura, Yasunori

    2012-01-01

    The gut is a tubular, endodermal organ for digesting food and absorbing nutrients. In this study, we characterized eight enhancer detection lines that express green fluorescent protein (GFP) in the whole or part of the digestive tube of the ascidian Ciona intestinalis. Three enhancer detection lines for the pyloric gland, a structure associated with the digestive tube, were also analyzed. These lines are valuable markers for analyzing the mechanisms of development of the gut. Based on the GFP expression of the enhancer detection lines together with morphological characteristics, the digestive tube of Ciona can be subdivided into at least 10 compartments in which different genetic cascades operate. Causal insertion sites of the enhancer detection lines were identified, and the expression pattern of the genes near the insertion sites were characterized by means of whole-mount in situ hybridization. We have characterized four and two genes that were specifically or strongly expressed in the digestive tube and pyloric gland, respectively. The present data provide the basic information and useful resources for studying gut formation in Ciona.

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

    PubMed Central

    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

  16. Siphon Regeneration Capacity is Compromised During Aging in the Ascidian Ciona intestinalis

    PubMed Central

    Jeffery, William R.

    2012-01-01

    The ascidian Ciona intestinalis has a short life span and powerful regeneration capacities. The regeneration of the oral siphon (OS) involves wound healing, blastema formation, cell proliferation, and replacement of eight oral pigment organs (OPO), the latter via differentiation and migration of stem/precursor cells from localized siphon niches in the siphon. The restoration of OPO pattern during OS regeneration occurs with a high degree of accuracy through three successive cycles of amputation. It is shown here that oral siphons of the largest and oldest members of a wild Ciona population do not completely regenerate their siphons after amputation. The loss of regeneration capacity was accompanied by reduced cell proliferation. In contrast to arrested OS outgrowth, the stem/precursor cells responsible for OPO replacement “over-differentiate” after OS amputation in the oldest animals, the typical number of OPO is increased from eight to twelve-sixteen, and malformed OPO are produced. Also in contrast to younger animals, the oldest animals of the population show arrested OPO development after two consecutive cycles of amputation and regeneration. We conclude that there is a size and age threshold in Ciona after which the regenerative capacity of the OS is compromised due to effects of aging on cell proliferation. PMID:22935550

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

    PubMed

    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.

  18. Cortical anchorages and cell type segregations of maternal postplasmic/PEM RNAs in ascidians.

    PubMed

    Paix, Alexandre; Yamada, Lixy; Dru, Philippe; Lecordier, Helene; Pruliere, Gerard; Chenevert, Janet; Satoh, Nori; Sardet, Christian

    2009-12-01

    Ascidian postplasmic/PEM RNAs constitute a large class of cortical maternal RNAs which include developmental determinants (macho-1 and pem-1). We have analyzed the localization, cortical anchorage and cell type segregation of postplasmic/PEM RNAs in Ciona intestinalis and Phallusia mammillata using very high-resolution fluorescent in situ hybridization. We also compared RNAs extracted from whole oocytes and from isolated cortices using microarrays and localized RNAs possessing clusters of xCACx motifs in their 3'UTRs. Based on these combined approaches we conclude that: (1) the vast majority of the 39 postplasmic/PEM RNAs (including vasa) are localized in the egg cortex. (2) Many postplasmic/PEM RNAs 3'UTR are enriched in xCACx motifs, allowing us to identify 2 novel postplasmic/PEM RNAs (PSD and MnK). (3) Postplasmic/PEM RNAs anchored to cortical Endoplasmic Reticulum (cER) and those associated with granules have different cell destinations. We propose that there are 2 distinct categories of postplasmic/PEM RNAs on the basis of their cortical anchorages and cell destinations: (1) macho-1-like postplasmic/PEM RNAs anchored to cER which segregate into somatic B8.11 cells. (2) vasa-like postplasmic/PEM RNAs associated with granules which in addition to B8.11 cells segregate into B8.12 germ cells.

  19. Global Phylogeography of the Widely Introduced North West Pacific Ascidian Styela clava

    PubMed Central

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

    2011-01-01

    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. PMID:21364988

  20. Reprotoxicity of the Antifoulant Chlorothalonil in Ascidians: An Ecological Risk Assessment

    PubMed Central

    Gallo, Alessandra; Tosti, Elisabetta

    2015-01-01

    Chlorothalonil is a widely used biocide in antifouling paint formulation that replaces tin-based compounds after their definitive ban. Although chlorothalonil inputs into the marine environment have significantly increased in recent years, little is known about its effect on marine animals and in particular on their reproductive processes. In this line, the aim of the present study was to investigate the effects of chlorothalonil exposure on the gamete physiology, fertilization rate and transmissible damage to offspring in the marine invertebrate Ciona intestinalis (ascidians). To identify a possible mechanism of action of chlorothalonil, electrophysiological techniques were used to study the impact on oocyte membrane excitability and on the electrical events occurring at fertilization. The pre-exposure of spermatozoa and oocytes to chlorothalonil did not affect the fertilization rate but caused damage to the offspring by inducing larval malformation. The highest toxicity was observed when fertilization was performed in chlorothalonil solutions with the lowest EC50 value. In particular, it was observed that low chlorothalonil concentrations interfered with embryo development and led to abnormal larvae, whereas high concentrations arrested embryo formation. In mature oocytes, a decrease in the amplitudes of the sodium and fertilization currents was observed, suggesting an involvement of plasma membrane ion currents in the teratogenic mechanism of chlorothalonil action. The risk estimation confirmed that the predicted no-effect concentration (PNEC) exceeded the predicted effect concentration (PEC), thus indicating that chlorothalonil may pose a risk to aquatic species. PMID:25875759

  1. Immunotoxicity in ascidians: antifouling compounds alternative to organotins-IV. The case of zinc pyrithione.

    PubMed

    Cima, Francesca; Ballarin, Loriano

    2015-03-01

    New biocides such as the organometallic compound zinc pyrithione (ZnP) have been massively introduced by many countries in formulations of antifouling paints following the ban on tributyltin (TBT). The effects of sublethal concentrations (LC50=82.5 μM, i.e., 26.2 mg/l) on cultured haemocytes of the ascidian Botryllus schlosseri have been investigated and compared with TBT. The percentage of haemocytes with amoeboid morphology and containing phagocytised yeast cells were significantly (p<0.05) reduced after exposure to 0.1 (31.7 μg/l) and 0.5 μM (158 μg/l), respectively. An antagonistic interaction in inducing cytoskeletal alterations was observed when ZnP and TBT were co-present in the exposure medium. ZnP affected only the actin component. As caused by TBT, ZnP induced apoptosis and inhibited both oxidative phosphorylation and lysosomal activities. In contrast to the case of TBT, a decrement in Ca(2+)-ATPase activity and a decrease in cytosolic Ca(2+) were detected after incubation at the highest concentration (1 μM, i.e., 317.7 μg/l) used. In comparison with other antifouling compounds, ZnP shows as much toxicity as TBT to cultured haemocytes at extremely low concentrations interfering with fundamental cell activities.

  2. Multilocus genetic analyses differentiate between widespread and spatially restricted cryptic species in a model ascidian.

    PubMed

    Bock, Dan G; MacIsaac, Hugh J; Cristescu, Melania E

    2012-06-22

    Elucidating the factors that shape species distributions has long been a fundamental goal in ecology and evolutionary biology. In spite of significant theoretical advancements, empirical studies of range limits have lagged behind. Specifically, little is known about how the attributes that allow species to expand their ranges and become widespread vary across phylogenies. Here, we studied the ascidian Botryllus schlosseri, a worldwide invasive species that is also characterized by marked genetic subdivision. Our study includes phylogenetic and population genetic data based on mitochondrial and nuclear genes, as well as polymorphic microsatellites for B. schlosseri colonies sampled from the southern and northern coasts of Europe and the eastern and western coasts of North America. We demonstrate that this well-known model organism comprises three highly divergent and probably reproductively isolated cryptic species (A, D and E), with two more (B and C) being suggested by data retrieved from GenBank. Among these, species A, recovered in all of the surveyed regions, is by far the most common and widespread. By contrast, species B-E, occurring mostly in sites from northern Europe, are considerably more geographically restricted. These findings, along with inferences made on transport opportunity, suggest that divergent evolutionary histories promoted differences in invasive potential between B. schlosseri sibling species, indicating that attributes that facilitate dramatic shifts in range limits can evolve more easily and frequently than previously thought. We propose environmental disturbance as a selective force that could have shaped the evolution of invasiveness in the B. schlosseri complex.

  3. Mechanisms of helical swimming: asymmetries in the morphology, movement and mechanics of larvae of the ascidian Distaplia occidentalis.

    PubMed

    McHenry, M J

    2001-09-01

    A great diversity of unicellular and invertebrate organisms swim along a helical path, but it is not well understood how asymmetries in the body shape or the movement of propulsive structures affect a swimmer's ability to perform the body rotation necessary to move helically. The present study found no significant asymmetries in the body shape of ascidian larvae (Distaplia occidentalis) that could operate to rotate the body during swimming. By recording the three-dimensional movement of free-swimming larvae, it was found that the tail possessed two bends, each with constant curvature along their length. As these bends traveled posteriorly, the amplitude of curvature changes was significantly greater in the concave-left direction than in the concave-right direction. In addition to this asymmetry, the tail oscillated at an oblique angle to the midline of the trunk. These asymmetries generated a yawing moment that rotated the body in the counterclockwise direction from a dorsal view, according to calculations from hydrodynamic theory. The tails of resting larvae were bent in the concave-left direction with a curvature statistically indistinguishable from the median value for tail curvature during swimming. The flexural stiffness of the tails of larvae, measured in three-point bending, may be great enough to allow the resting curvature of the tail to have an effect on the symmetry of kinematics. This work suggests that asymmetrical tail motion is an important mechanism for generating a yawing moment during swimming in ascidian larvae and that these asymmetries may be caused by the tail's bent shape. Since helical motion requires that moments also be generated in the pitching or rolling directions, other mechanisms are required to explain fully how ascidian larvae generate and control helical swimming.

  4. SL RNA genes of the ascidian tunicates Ciona intestinalis and Ciona savignyi.

    PubMed

    Yeats, Brendan; Matsumoto, Jun; Mortimer, Sandra I; Shoguchi, Eiichi; Satoh, Nori; Hastings, Kenneth E M

    2010-02-01

    We characterized by bioinformatics the trans-spliced leader donor RNA (SL RNA) genes of two ascidians, Ciona intestinalis and Ciona savignyi. The Ciona intestinalis genome contains approximately 670 copies of the SL RNA gene, principally on a 264-bp tandemly repeated element. Fluorescent in-situ hybridization mapped most of the repeats to a single site on the short arm of chromosome 8. The Ciona intestinalis genome also contains approximately 100 copies of a >3.6-kb element that carries 1) an SL RNA-related sequence (possible a pseudogene) and 2) genes for the U6 snRNA and a histone-like protein. The Ciona savignyi genome contains two SL RNA gene classes having the same SL sequence as Ciona intestinalis but differing in the intron-like segments. These reside in similar but distinct repeat units of 575 bp ( approximately 410 copies) and 552 bp ( approximately 250 copies) that are arranged as separate tandem repeats. In neither Ciona species is the 5S RNA gene present within the SL RNA gene repeat unit. Although the number of SL RNA genes is similar, there is little sequence similarity between the intestinalis and savignyi repeat units, apart from the region encoding the SL RNA itself. This suggests that cis-regulatory elements involved in transcription and 3'-end processing are likely to be present within the transcribed region. The genomes of both Ciona species also include > 100 dispersed short elements containing the 16-nt SL sequence and up to 6 additional nucleotides of the SL RNA sequence.

  5. The candidate Fu/HC gene in Botryllusschlosseri (Urochordata) and ascidians' historecognition--an oxymoron?

    PubMed

    Rinkevich, Buki; Douek, Jacob; Rabinowitz, Claudette; Paz, Guy

    2012-04-01

    Allorecognition, distinguishing self from non-self allogeneic tissues is the underlying basis of innate immunity. In the colonial tunicate Botryllus schlosseri this historecognition is governed at a single genetic locus, Fu/HC (for fusibility/histocompatibility), with hundreds of co-dominantly expressed alleles. Several years ago, De Tomaso et al. (2005) have revolutionized the discipline of invertebrate allorecognition by describing a novel form of immune recognition in B. schlosseri, a non-vertebrate candidate histocompatibility gene (cFu/HC), revealing that allorecognition machinery in urochordates has nothing in common with the vertebrates' MHC-based histocompatibility. The authors reported absolute concordance of fusibility and cFu/HC genotype, predicted fusion/rejection outcomes in allorecognition settings from allelic polymorphism at the cFu/HC, also claiming cFu/HC gene expressions only in tissues directly engaged in histocompatibility. Here, we raise queries for the validity of the results and conclusions of De Tomaso et al. (2005) publication. Our reservations include discrepancies in the paper's results, including the perplexing absence of key sequencing material from public domains and above all, our own impugning outcomes. These include cloning efforts, in situ hybridization results, semi quantitative PCR outcomes, and the incongruence emerged between fusion/rejection profiles and cFu/HC segregated polymorphism that separately and cumulatively contradict the original publication. We conclude that Botryllus histocompatibility properties are not signaled in the claimed cFu/HC and that cFu/HC gene is unlikely the allodeterminant for Botryllus histocompatibility locus. Hence, the molecular nature of the Fu/HC locus in botryllid ascidians is still awaiting elucidation.

  6. Phylogenetics, biogeography and population genetics of the ascidian Botryllus schlosseri in the Mediterranean Sea and beyond.

    PubMed

    Reem, Eitan; Douek, Jacob; Paz, Guy; Katzir, Gadi; Rinkevich, Baruch

    2017-02-01

    The wide distribution of the ascidian Botryllus schlosseri along the Mediterranean coasts has been documented since the eighteenth century. However, despite copious documentation, analyses of dispersal modes and genetic profiles were limited to local populations or restricted regions. In order to get a pan-Mediterranean overview, 288 specimens from 11 populations of B. schlosseri from the western and eastern Mediterranean basins were sampled and analyzed using five microsatellite loci and COI sequences. Both molecular markers revealed high polymorphisms, with 182 microsatellites alleles and 54 COI haplotypes. Overall, Fst, Dest, and COI Фpt values were 0.146, 0.635 and 0.322, respectively, reflecting a high genetic diversity and a significant genetic structure as compared to other B. schlosseri populations worldwide, reflected by substantially higher values for effective number of alleles (Ne) in the Mediterranean. A phylogenetic analysis of the COI sequences resulted in four distinct clades and two molecular operational taxonomic units (OTUs). We recorded a stronger genetic structure among the populations of the eastern basin compared to the western basin (microsatellites Fst=0.217 versus 0.082; COI Фpt=0.416 versus 0.171), suggesting either a restricted connectivity between the basins or a stronger genetic drift in each basin. The occurrence of two OTUs and different ecological conditions may also contribute to this finding. Mean Nei's genetic distance in the eastern Mediterranean populations was more than three times higher compared to the western basin. No correlation was observed between geographic and genetic distances (Mantel test), suggesting that maritime transport is the main dispersal vector of B. schlosseri colonies. The possibility that the Mediterranean is a center of diversity for B. schlosseri, and probably its site of origin, is further discussed.

  7. Metamorphosis of the invasive ascidian Ciona savignyi: environmental variables and chemical exposure.

    PubMed

    Cahill, Patrick L; Atalah, Javier; Selwood, Andrew I; Kuhajek, Jeanne M

    2016-01-01

    In this study, the effects of environmental variables on larval metamorphosis of the solitary ascidian Ciona savignyi were investigated in a laboratory setting. The progression of metamorphic changes were tracked under various temperature, photoperiod, substrate, larval density, and vessel size regimes. Metamorphosis was maximised at 18 °C, 12:12 h subdued light:dark, smooth polystyrene substrate, and 10 larvae mL(-1) in a twelve-well tissue culture plate. Eliminating the air-water interface by filling culture vessels to capacity further increased the proportion of metamorphosed larvae; 87 ± 5% of larvae completed metamorphosis within 5 days compared to 45 ± 5% in control wells. The effects of the reference antifouling compounds polygodial, portimine, oroidin, chlorothalonil, and tolylfluanid on C. savignyi were subsequently determined, highlighting (1) the sensitivity of C. savignyi metamorphosis to chemical exposure and (2) the potential to use C. savignyi larvae to screen for bioactivity in an optimised laboratory setting. The compounds were bioactive in the low ng mL(-1) to high µg mL(-1) range. Polygodial was chosen for additional investigations, where it was shown that mean reductions in the proportions of larvae reaching stage E were highly repeatable both within (repeatability = 14 ± 9%) and between (intermediate precision = 17 ± 3%) independent experiments. An environmental extract had no effect on the larvae but exposing larvae to both the extract and polygodial reduced potency relative to polygodial alone. This change in potency stresses the need for caution when working with complex samples, as is routinely implemented when isolating natural compounds from their biological source. Overall, the outcomes of this study highlight the sensitivity of C. savignyi metamorphosis to environmental variations and chemical exposure.

  8. The Whereabouts of an Ancient Wanderer: Global Phylogeography of the Solitary Ascidian Styela plicata

    PubMed Central

    Pineda, Mari Carmen; López-Legentil, Susanna; Turon, Xavier

    2011-01-01

    Genetic tools have greatly aided in tracing the sources and colonization history of introduced species. However, recurrent introductions and repeated shuffling of populations may have blurred some of the genetic signals left by ancient introductions. Styela plicata is a solitary ascidian distributed worldwide. Although its origin remains unclear, this species is believed to have spread worldwide by travelling on ship's hulls. The goals of this study were to infer the genetic structure and global phylogeography of S. plicata and to look for present-day and historical genetic patterns. Two genetic markers were used: a fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) and a fragment of the nuclear gene Adenine Nucleotide Transporter/ADP-ATP Translocase (ANT). A total of 368 individuals for COI and 315 for ANT were sequenced from 17 locations worldwide. The levels of gene diversity were moderate for COI to high for ANT. The Mediterranean populations showed the least diversity and allelic richness for both markers, while the Indian, Atlantic and Pacific Oceans had the highest gene and nucleotide diversities. Network and phylogenetic analyses with COI and ANT revealed two groups of alleles separated by 15 and 4 mutational steps, respectively. The existence of different lineages suggested an ancient population split. However, the geographic distributions of these groups did not show any consistent pattern, indicating different phylogeographic histories for each gene. Genetic divergence was significant for many population-pairs irrespective of the geographic distance among them. Stochastic introduction events are reflected in the uneven distribution of COI and ANT allele frequencies and groups among many populations. Our results confirmed that S. plicata has been present in all studied oceans for a long time, and that recurrent colonization events and occasional shuffling among populations have determined the actual genetic structure of this species

  9. Biology of the invasive ascidian Ascidiella aspersa in its native habitat: Reproductive patterns and parasite load

    NASA Astrophysics Data System (ADS)

    Lynch, Sharon A.; Darmody, Grainne; O'Dwyer, Katie; Gallagher, Mary Catherine; Nolan, Sinead; McAllen, Rob; Culloty, Sarah C.

    2016-11-01

    The European sea squirt Ascidiella aspersa is a solitary tunicate native to the northeastern Atlantic, commonly found in shallow and sheltered marine ecosystems where it is capable of forming large clumps and outcompeting other invertebrate fauna at settlement. To date, there have been relatively few studies looking at the reproductive biology and health status of this invasive species. Between 2006 and 2010 sampling of a native population took place to investigate gametogenesis and reproductive cycle and to determine the impact of settlement depth on reproduction. In addition, parasite diversity and impact was assessed. A staging system to assess reproductive development was determined. The study highlighted that from year to year the tunicate could change its reproductive strategy from single sex to hermaphrodite, with spawning possible throughout the year. Depth did not impact on sex determination, however, gonad maturation and spawning occurred earlier in individuals in deeper waters compared to shallow depth and it also occurred later in A. aspersa at sites further away from the open sea. Four significant parasite groups including eugregarines, ciliates, trematodes and turbellarians were detected and prevalence of parasite infections increased in A. aspersa at sites with a reduced water flow rate. This study demonstrates the high biotic potential of this ascidian bioinvader to have a negative impact on native fauna in an introduced ecosystem, due to its highly efficient reproductive and resource allocation strategies. Artificial structures such as mooring lines can harbour large aggregations of A. aspersa, however, these manmade habitats may facilitate the colonisation and establishment of this invasive species in the benthos. Additionally, the parasite communities that A. aspersa harbour may also exacerbate its negative impact, both ecologically and economically, in an introduced area by possibly leading to the emergence of new disease in native species i

  10. Metamorphosis of the invasive ascidian Ciona savignyi: environmental variables and chemical exposure

    PubMed Central

    Atalah, Javier; Selwood, Andrew I.; Kuhajek, Jeanne M.

    2016-01-01

    In this study, the effects of environmental variables on larval metamorphosis of the solitary ascidian Ciona savignyi were investigated in a laboratory setting. The progression of metamorphic changes were tracked under various temperature, photoperiod, substrate, larval density, and vessel size regimes. Metamorphosis was maximised at 18 °C, 12:12 h subdued light:dark, smooth polystyrene substrate, and 10 larvae mL−1 in a twelve-well tissue culture plate. Eliminating the air-water interface by filling culture vessels to capacity further increased the proportion of metamorphosed larvae; 87 ± 5% of larvae completed metamorphosis within 5 days compared to 45 ± 5% in control wells. The effects of the reference antifouling compounds polygodial, portimine, oroidin, chlorothalonil, and tolylfluanid on C. savignyi were subsequently determined, highlighting (1) the sensitivity of C. savignyi metamorphosis to chemical exposure and (2) the potential to use C. savignyi larvae to screen for bioactivity in an optimised laboratory setting. The compounds were bioactive in the low ng mL−1 to high µg mL−1 range. Polygodial was chosen for additional investigations, where it was shown that mean reductions in the proportions of larvae reaching stage E were highly repeatable both within (repeatability = 14 ± 9%) and between (intermediate precision = 17 ± 3%) independent experiments. An environmental extract had no effect on the larvae but exposing larvae to both the extract and polygodial reduced potency relative to polygodial alone. This change in potency stresses the need for caution when working with complex samples, as is routinely implemented when isolating natural compounds from their biological source. Overall, the outcomes of this study highlight the sensitivity of C. savignyi metamorphosis to environmental variations and chemical exposure. PMID:26966668

  11. The invariant cleavage pattern displayed by ascidian embryos depends on spindle positioning along the cell's longest axis in the apical plane and relies on asynchronous cell divisions

    PubMed Central

    Dumollard, Rémi; Minc, Nicolas; Salez, Gregory; Aicha, Sameh Ben; Bekkouche, Faisal; Hebras, Céline; Besnardeau, Lydia; McDougall, Alex

    2017-01-01

    The ascidian embryo is an ideal system to investigate how cell position is determined during embryogenesis. Using 3D timelapse imaging and computational methods we analyzed the planar cell divisions in ascidian early embryos and found that spindles in every cell tend to align at metaphase in the long length of the apical surface except in cells undergoing unequal cleavage. Furthermore, the invariant and conserved cleavage pattern of ascidian embryos was found to consist in alternate planar cell divisions between ectoderm and endomesoderm. In order to test the importance of alternate cell divisions we manipulated zygotic transcription induced by β-catenin or downregulated wee1 activity, both of which abolish this cell cycle asynchrony. Crucially, abolishing cell cycle asynchrony consistently disrupted the spindle orienting mechanism underpinning the invariant cleavage pattern. Our results demonstrate how an evolutionary conserved cell cycle asynchrony maintains the invariant cleavage pattern driving morphogenesis of the ascidian blastula. DOI: http://dx.doi.org/10.7554/eLife.19290.001 PMID:28121291

  12. Transmission of cyanobacterial symbionts during embryogenesis in the coral reef ascidians Trididemnum nubilum and T. clinides (Didemnidae, Ascidiacea, Chordata).

    PubMed

    Kojima, Aoi; Hirose, Euichi

    2012-02-01

    Vertical transmission of cyanobacterial symbionts occurs in didemnid ascidians harboring Prochloron as an obligate symbiont; the photosymbionts are transferred from the parental ascidian colony to the offspring in various ways depending on host species. Although several didemnids harbor non-Prochloron cyanobacteria in their tunics, few studies have reported the processes of vertical transmission in these didemnids. Here we describe the histological processes of the transmission of cyanobacteria in two didemnids, Trididemnum nubilum harboring Synechocystis and T. clinides harboring three cyanobacterial species. In both species, the photosymbionts in the tunic of the parent colony were apparently captured by the tunic cells of the host and transferred to the embryos brooded in the tunic. The symbiont cells were then incorporated into the inner tunic of the embryo. This mode of transmission is essentially the same as that of T. miniatum harboring Prochloron in the tunic, although there are some differences among species in the timing of the release of the symbionts from the tunic cells. We suggest that the similar modes of vertical transmission are an example of convergent evolution caused by constraints in the distribution patterns of symbiont cells in the host colony.

  13. Toxic effects of two pesticides, Imazalil and Triadimefon, on the early development of the ascidian Phallusia mammillata (Chordata, Ascidiacea).

    PubMed

    Pennati, Roberta; Groppelli, Silvia; Zega, Giuliana; Biggiogero, Maira; De Bernardi, Fiorenza; Sotgia, Cristina

    2006-09-12

    Azole compounds are fungicides used in agriculture and in clinical area and are suspected to produce craniofacial malformations in vertebrates. Toxicity tests on sperm viability, fertilization and embryogenesis of the solitary ascidian Phallusia mammillata were performed to evaluate the effects of two azole derivatives, Imazalil and Triadimefon. Ascidian (Chordata, Ascidiacea) embryos and larvae could provide biological criteria for seawater quality standards because the larvae are lecitotrophic and have a short pelagic period, allowing to run the larval toxicity tests over a short period of time. Imazalil and Triadimefon proved to have strong consequences on P. mammillata. They could influence the reproductive rate of the animal exerting their effects at different levels: acting as spermiotoxic agents, inhibiting fertilization and impairing embryological development. Fertilization rate significantly decreased after 30min exposure of sperm to 25microM Imazalil (P<0.0001) and after exposure of both gametes to 50microM Imazalil (P<0.05) and 1mM Triadimefon (P<0.0001) as compared to controls. Malformations caused by exposure of embryos to both substances were dose dependent. Imazalil median teratogenic concentration (TC50 concentration, the concentration that resulted in 50% malformed larvae) value was 0.67microM and median lethal concentration (LC50, the concentration that resulted in 50% embryos dead before completing the development) value was 10.23microM while for Triadimefon TC50 value was 29.56 and LC50 value was 173.7microM. Larvae developed from embryos treated with Imazalil and Triadimefon showed alterations of the anterior structures of the trunk: papillary nerves and the anterior central nervous system failed to correctly differentiate, as showed by immunostaining with anti-beta-tubulin antibody. Comparing the anomalies caused by retinoic acid, reported in a previous study, it was possible to hypothesize that malformations induced by Imazalil and

  14. A new genus of Asterocheridae (Copepoda: Siphonostomatoida) ectoassociate of the ascidian Eudistoma vannamei Millar, 1977 (Polycitoridae) from Brazil.

    PubMed

    Johnsson, Rodrigo; Bahia, Cristiano; Neves, Elizabeth

    2016-05-23

    Asterocheres Boeck, 1860 is the largest genus of the siphonostomatoid copepod family Asterocheridae, containing 63 valid species. The genus is known for its symbiotic relationships with many marine invertebrate taxa, especially sponges, cnidarians, bryozoans, and echinoderms. Recent studies have restricted the diagnosis of this genus. Consequently, many species are now considered as species inquirendae. The present paper describes a new species living externally on the tunic of Eudistoma vannamei Millar, 1977, an endemic ascidian from Brazil. As the new species does not fit Asterocheres in the strict sense, a new genus is erected to accommodate it. Setacheres gen. nov. is characterized by its possession of two distal setae on the third endopodal segment of P3, thus differing from the distal seta and spine pattern that is deemed as diagnostic of Asterocheres. A revision and comparison of Asterocheres´ species inquirendae revealed eight species sharing the same generic characteristics and were thus reallocated as members of the new genus.

  15. Interspecific hybridization between an anural and urodele ascidian: differential expression of urodele features suggests multiple mechanisms control anural development.

    PubMed

    Swalla, B J; Jeffery, W R

    1990-12-01

    Anural development in the ascidian Molgula occulta was examined using tissue-specific markers and interspecific hybridization. Unlike most ascidians, which develop into a swimming tadpole larva (urodele development), M. occulta eggs develop into a tailless slug-like larva (anural development) which metamorphoses into an adult. M. occulta embryos show conventional early cleavage patterns, gastrulation, and neurulation, but then diverge from the urodele developmental mode during larval morphogenesis. M. occulta larvae do not contain a pigmented sensory cell in their brain or form a tail with differentiated notochord and muscle cells. As shown by in situ hybridization with cloned probes and analysis of in vitro translation products, M. occulta embryos do not accumulate high levels of alpha actin or myosin heavy chain mRNA. In contrast, acetylcholinesterase is expressed in muscle lineage cells, indicating that various muscle cell features are differentially suppressed. M. occulta embryos also lack tyrosinase activity, suggesting that suppression of brain pigment cell differentiation occurs at an early step in development. M. occulta eggs fertilized with sperm from Molgula oculata (a closely related urodele species) develop into hybrid larvae exhibiting some of the missing urodele features. Some hybrid embryos develop tyrosinase activity and differentiate a brain pigment cell and a short row of notochord cells, and form a short tail. These urodele features appeared together or separately in different hybrid embryos suggesting that they develop by independent mechanisms. In contrast, alpha actin and myosin heavy chain mRNA accumulation was not enhanced in hybrid embryos. These results suggest that multiple mechanisms control anural development.

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

    PubMed

    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.

  17. Complete mtDNA of Ciona intestinalis reveals extensive gene rearrangement and the presence of an atp8 and an extra trnM gene in ascidians.

    PubMed

    Gissi, Carmela; Iannelli, Fabio; Pesole, Graziano

    2004-04-01

    The complete mitochondrial genome (mtDNA) of the model organism Ciona intestinalis (Urochordata, Ascidiacea) has been amplified by long-PCR using specific primers designed on putative mitochondrial transcripts identified from publicly available mitochondrial-like expressed sequence tags. The C. intestinalis mtDNA encodes 39 genes: 2 rRNAs, 13 subunits of the respiratory complexes, including ATPase subunit 8 ( atp8), and 24 tRNAs, including 2 tRNA-Met with anticodons 5'-UAU-3'and 5'-CAU-3', respectively. All genes are transcribed from the same strand. This gene content seems to be a common feature of ascidian mtDNAs, as we have verified the presence of a previously undetected atp8 and of two trnM genes in the two other sequenced ascidian mtDNAs. Extensive gene rearrangement has been found in C. intestinalis with respect not only to the common Vertebrata/Cephalochordata/Hemichordata gene organization but also to other ascidian mtDNAs, including the cogeneric Ciona savignyi. Other features such as the absence of long noncoding regions, the shortness of rRNA genes, the low GC content (21.4%), and the absence of asymmetric base distribution between the two strands suggest that this genome is more similar to those of some protostomes than to deuterostomes.

  18. Effects of the azole fungicide Imazalil on the development of the ascidian Ciona intestinalis (Chordata, Tunicata): morphological and molecular characterization of the induced phenotype.

    PubMed

    Zega, Giuliana; De Bernardi, Fiorenza; Groppelli, Silvia; Pennati, Roberta

    2009-02-19

    Imazalil (IMA) is a fungicide that is used extensively in fruit plantations and post-harvest treatments, but has teratogenic effects on vertebrate development, possibly due to the perturbation of retinoic acid (RA) levels in the embryo. Ascidians are sessile marine invertebrate chordates that develop through a tadpole larva, with a body plan that shares basic homologies with vertebrates. In this work, we tested the effects of IMA on the development of the solitary ascidian Ciona intestinalis by treating two-cell stage embryos with a range of concentrations (0.1, 0.5, 1, 2.5, 5, 10, 20 and 50microThe fungicide significantly altered ascidian development even at low concentrations and its effects were dose-dependent. Probit analysis revealed that the median lethal concentration, LC(50), was 4.87microM and the median teratogenic concentration, TC(50), was 0.73microM. Larvae developing from embryos exposed to IMA showed malformations of the anterior structures, which became more severe as IMA concentration increased. In particular, the anterior nervous system and the sensory vesicle were reduced, and the pigmented organs (the ocellus and the otolith) progressively lost their pigmentation. The larval phenotype induced by 5microM IMA exposure was further characterized by means of molecular analysis, through whole mount in situ hybridization with probes for genes related to the nervous system: Ci-Otp, Ci-GAD, Ci-POU IV, which are markers of the anterior neuro-ectoderm, the central nervous system and the peripheral nervous system respectively, and Ci-Hox-1, a gene specifically activated by RA, and Ci-Aldh2, a gene for aldehyde dehydrogenase, which is involved in RA synthesis. The altered expression of Ci-Otp, Ci-GAD, Ci-POU IV in 5microM IMA-exposed larvae compared to control larvae showed that this fungicide could affect the differentiation of the anterior nervous system, particularly of the sensory vesicle neurons. Recent studies suggest a similarity between IMA- and RA

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

    PubMed

    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.

  20. Closing the wounds: one hundred and twenty five years of regenerative biology in the ascidian Ciona intestinalis.

    PubMed

    Jeffery, William R

    2015-01-01

    This year marks the 125th anniversary of the beginning of regeneration research in the ascidian Ciona intestinalis. A brief note was published in 1891, reporting the regeneration of the Ciona neural complex and siphons. This launched an active period of Ciona regeneration research culminating in the demonstration of partial body regeneration: the ability of proximal body parts to regenerate distal ones, but not vice versa. In a process resembling regeneration, wounds in the siphon tube were discovered to result in the formation of an ectopic siphon. Ciona regeneration research then lapsed into a period of relative inactivity after the purported demonstration of the inheritance of acquired characters using siphon regeneration as a model. Around the turn of the present century, Ciona regeneration research experienced a new blossoming. The current studies established the morphological and physiological integrity of the regeneration process and its resemblance to ontogeny. They also determined some of the cell types responsible for tissue and organ replacement and their sources in the body. Finally, they showed that regenerative capacity is reduced with age. Many other aspects of regeneration now can be studied at the mechanistic level because of the extensive molecular tools available in Ciona.

  1. T-Type Ca2+ Current Activity during Oocyte Growth and Maturation in the Ascidian Styela plicata

    PubMed Central

    Gallo, Alessandra; Russo, Gian Luigi; Tosti, Elisabetta

    2013-01-01

    Voltage-dependent calcium currents play a fundamental role during oocyte maturation, mostly L-type calcium currents, whereas T-type calcium currents are involved in sperm physiology and cell growth. In this paper, using an electrophysiological and pharmacological approach, we demonstrated, for the first time in oocytes, that T-type calcium currents are present with functional consequences on the plasma membrane of growing immature oocytes of the ascidian Styela plicata. We classified three subtypes of immature oocytes at the germinal vesicle stage on the basis of their size, morphology and accessory cellular structures. These stages were clearly associated with an increased activity of T-type calcium currents and hyperpolarization of the plasma membrane. We also observed that T-type calcium currents oscillate in the post-fertilization embryonic stages, with minimal amplitude of the currents in the zygote and maximal at 8-cell stage. In addition, chemical inhibition of T-type calcium currents, obtained by applying specific antagonists, induced a significant reduction in the rate of cleavage and absence of larval formation. We suggest that calcium entry via T-type calcium channels may act as a potential pacemaker in regulating cytosolic calcium involved in fertilization and early developmental events. PMID:23349937

  2. Catecholamines are produced by ascidian immune cells: The involvement of PKA and PKC in the adrenergic signaling pathway.

    PubMed

    de Abreu Mello, Andressa; Fernandes de Souza, Jéssica; Nunes da Fonseca, Rodrigo; Allodi, Silvana; Monteiro de Barros, Cintia

    2017-03-01

    The stress response is a complex mechanism, which includes changes in the immune system to enable organisms to maintain homeostasis. The neurohormones dopamine, noradrenaline (NA) and adrenalin are responsible for the physiological modulations that occur during acute stress. In the present study, we analyzed the effects of NA on the immune system specific to nitric-oxide (NO) production by subpopulations of immune cells (hemocytes) of the ascidian Phallusia nigra. We also investigated the capability of immune cells to produce catecholamine (CA). Finally, we tested the involvement of protein kinase A (PKA) and C (PKC) in the NA downstream signaling pathway. The results revealed that NA can reduce NO production by P. nigra hemocytes threefold, and that signet-ring cells, univacuolar refractile granulocytes and morula cells are the cell types most involved in this event. A challenge effected with Zymosan A induced CA production, and co-incubation with both inhibitors of the second messengers PKA and PKC revealed the involvement of these molecules in the adrenergic pathway of P. nigra hemocytes. Taken together, these results suggest that NO production can be down-regulated by NA through α- and β-adrenoceptors via the second messengers PKA and PKC.

  3. Msxb is a core component of the genetic circuitry specifying the dorsal and ventral neurogenic midlines in the ascidian embryo.

    PubMed

    Roure, Agnès; Darras, Sébastien

    2016-01-01

    The tail ascidian larval peripheral nervous system is made up of epidermal sensory neurons distributed more or less regularly in ventral and dorsal midlines. Their formation occurs in two-steps: the ventral and dorsal midlines are induced as neurogenic territories by Fgf9/16/20 and Admp respectively. The Delta2/Notch interaction then controls the number of neurons that form. The genetic machinery acting between the inductive processes taking place before gastrulation and neuron specification at tailbud stages are largely unknown. The analysis of seven transcription factors expressed in the forming midlines revealed an unexpected complexity and dynamic of gene expression. Their systematic overexpression confirmed that these genes do not interact following a linear cascade of activation. However, the integration of our data revealed the distinct key roles of the two upstream factors Msxb and Nkx-C that are the earliest expressed genes and the only ones able to induce neurogenic midline and ESN formation. Our data suggest that Msxb would be the primary midline gene integrating inputs from the ventral and dorsal inducers and launching a pan-midline transcriptional program. Nkx-C would be involved in tail tip specification, in maintenance of the pan-midline network and in a posterior to anterior wave controlling differentiation.

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

    PubMed Central

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

    2014-01-01

    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. PMID:25173874

  5. Larval adhesive organs and metamorphosis in ascidians. II. The mechanism of eversion of the papillae of Distaplia occidentalis.

    PubMed

    Cloney, R A

    1979-09-01

    The cup-shaped adhesive papillae of Distaplia occidentalis evert at the onset of metamorphosis and each transforms into a hyperboloidal configuration. The rate of transformation is a function of temperature. At 14 degrees C complete eversion takes about 30 seconds. Myoepithelial cells that extend from the rim to the base on the cup contract. Simultaneously the central part of the papilla advances 60--70 micrometers. During the last phases of eversion, collocytes (cells that secrete adhesives) on the inner wall of the cup and on the sides of the axial protrusion flow outward and form a collar-like structure. The myoepithelial cells contain arrays of thick and thin filaments. These become compacted during contraction. The surfaces of these cells become extensively folded as they shorten to about 1/3 of rest length. According to the proposed model the myoepithelial cells are the driving force in papillary eversion. Immediately after eversion is completed the papillae begin to retract. Eversion of the papillae is not inhibited by cytochalasin B, but the process of retraction is reversibly inhibited. Some histological characteristics of five types of everting papillae in four families of ascidians are compared.

  6. Toxicity assessment of the antifouling compound zinc pyrithione using early developmental stages of the ascidian Ciona intestinalis.

    PubMed

    Bellas, Juan

    2005-01-01

    This study investigated the toxicity of zinc pyrithione (Zpt) on the early stages of development of the ascidian Ciona intestinalis. Larval morphological abnormalities were studied after the exposure of C. intestinalis embryos at different stages of development. The median effective concentrations (EC50) ranged from 226-590 nM. The larval settlement stage was the most sensitive to Zpt. Toxic effects of Zpt on larval settlement were detected at 9 nM (EC10). The inhibition of C. intestinalis embryonic development was also used to study the loss of toxicity in Zpt solutions exposed to direct sunlight and laboratory UV light. The results showed that the toxicity of Zpt solutions decreased but did not disappear after 4 h exposure to direct sunlight (EC50 = 484 nM) or UV light (EC50 = 453 nM), compared to control Zpt solutions prepared in dark conditions. On the basis of the present data, predicted no effect concentrations of Zpt to C. intestinalis larvae are lower than predicted environmental concentrations of Zpt in certain polluted areas and therefore, may pose a risk to C. intestinalis populations.

  7. Insulin-like genes in ascidians: findings in Ciona and hypotheses on the evolutionary origins of the pancreas

    PubMed Central

    Thompson, Jordan M.; Di Gregorio, Anna

    2014-01-01

    Insulin plays an extensively characterized role in the control of sugar metabolism, growth and homeostasis in a wide range of organisms. In vertebrate chordates, insulin is mainly produced by the beta cells of the endocrine pancreas, while in non-chordate animals insulin-producing cells are mainly found in the nervous system and/or scattered along the digestive tract. However, recent studies have indicated the notochord, the defining feature of the chordate phylum, as an additional site of expression of insulin-like peptides. Here we show that two of the three insulin-like genes identified in Ciona intestinalis, an invertebrate chordate with a dual life cycle, are first expressed in the developing notochord during embryogenesis and transition to distinct areas of the adult digestive tract after metamorphosis. In addition, we present data suggesting that the transcription factor Ciona Brachyury is involved in the control of notochord expression of at least one of these genes, Ciona insulin-like 2. Lastly, we review the information currently available on insulin-producing cells in ascidians and on pancreas-related transcription factors that might control their expression. PMID:25378051

  8. Lineage divergence, local adaptation across a biogeographic break, and artificial transport, shape the genetic structure in the ascidian Pyura chilensis.

    PubMed

    Segovia, Nicolás I; Gallardo-Escárate, Cristian; Poulin, Elie; Haye, Pilar A

    2017-03-16

    Marine benthic organisms inhabit a heterogeneous environment in which connectivity between populations occurs mainly through dispersive larval stages, while local selective pressures acting on early life history stages lead to non-random mortality, shaping adaptive genetic structure. In order to test the influence of local adaptation and neutral processes in a marine benthic species with low dispersal, in this study we used Genotyping by Sequencing technology to compare the neutral and putatively selected signals (neutral and outlier loci, respectively) in SNPs scattered throughout the genome in six local populations of the commercially exploited ascidian Pyura chilensis along the southeast Pacific coast (24°-42°S). This species is sessile as an adult, has a short-lived larval stage, and may also be dispersed by artificial transport as biofouling. We found that the main signal in neutral loci was a highly divergent lineage present at 39°S, and a subjacent signal that indicated a separation at 30°S (north/south), widely reported in the area. North/south separation was the main signal in outlier loci, and the linage divergence at 39°S was subjacent. We conclude that the geographic structure of the genetic diversity of outlier and neutral loci was established by different strengths of environmental, historical and anthropogenic factors.

  9. Photoadaptation and protection against active forms of oxygen in the symbiotic procaryote Prochloron sp. and its ascidian host

    SciTech Connect

    Lesser, M.P.; Stochaj, W.R. )

    1990-06-01

    Superoxide dismutase, ascorbate, peroxidase, and catalase activities were studied in the symbiotic photosynthetic procaryote Prochloron sp. and its ascidian host Lissoclinum patella. The protein-specific activities of these antioxidant enzymes in the Prochloron sp. and L. patella collected at different depths from the Great Barrier Reef, Australia, were directly proportional to irradiance, whereas the pigment concentrations in the Prochloron sp. were inversely proportional to irradiance. The presence of a cyanide-sensitive superoxide dismutase, presumably a Cu-An metalloprotein, in the Prochloron sp. extends the possible phylogenetic distribution of this protein. The concentration of UV-absorbing mycosporine-like amino acids in inversely proportional to irradiance in both the host and symbiont, suggesting that these compounds may not provide sufficient protection against UV radiation in high-irradiance environments. The significant differences in the specific activities of these antioxidant enzymes, cellular photosynthetic pigment concentrations, and UV-absorbing compounds from high- and low-irradiance habitats constitute an adaptive response to different photic environments. These photoadaptive responses are essential to prevent inhibition of photosynthesis by high fluxes of visible and UV radiation.

  10. Lineage divergence, local adaptation across a biogeographic break, and artificial transport, shape the genetic structure in the ascidian Pyura chilensis

    PubMed Central

    Segovia, Nicolás I.; Gallardo-Escárate, Cristian; Poulin, Elie; Haye, Pilar A.

    2017-01-01

    Marine benthic organisms inhabit a heterogeneous environment in which connectivity between populations occurs mainly through dispersive larval stages, while local selective pressures acting on early life history stages lead to non-random mortality, shaping adaptive genetic structure. In order to test the influence of local adaptation and neutral processes in a marine benthic species with low dispersal, in this study we used Genotyping by Sequencing technology to compare the neutral and putatively selected signals (neutral and outlier loci, respectively) in SNPs scattered throughout the genome in six local populations of the commercially exploited ascidian Pyura chilensis along the southeast Pacific coast (24°–42°S). This species is sessile as an adult, has a short-lived larval stage, and may also be dispersed by artificial transport as biofouling. We found that the main signal in neutral loci was a highly divergent lineage present at 39°S, and a subjacent signal that indicated a separation at 30°S (north/south), widely reported in the area. North/south separation was the main signal in outlier loci, and the linage divergence at 39°S was subjacent. We conclude that the geographic structure of the genetic diversity of outlier and neutral loci was established by different strengths of environmental, historical and anthropogenic factors. PMID:28300177

  11. cDNA cloning, localization, and candidate binding partners of acid-extractable vitelline-coat protein Ci-v-Themis-like in the ascidian Ciona intestinalis.

    PubMed

    Otsuka, Kei; Yamada, Lixy; Sawada, Hitoshi

    2013-10-01

    Ascidians are hermaphrodites, although several ascidian species show self-sterility because of the occurrence of a self/nonself-recognition system called the self-incompatibility system. We previously reported that two pairs of sperm polycystin 1-like receptors, s-Themis-A and s-Themis-B, and egg fibrinogen-like ligands, v-Themis-A and v-Themis-B, are responsible for self-incompatibility in the ascidian Ciona intestinalis. Our previous results showed that v-Themis-A and v-Themis-B were hardly extracted from the vitelline coat (VC) by acid treatment, which is not in accordance with a report that an acid-extractable VC factor has the ability to distinguish self- from nonself-sperm. These results led us to explore a novel factor from acid-extractable VC proteins that could be involved in self-incompatibility. Here, we report cDNA cloning, expression, and localization of Ci-v-Themis-like, a major acid-extractable VC protein. This protein has a fibrinogen-like domain, as do v-Themis-A and v-Themis-B, but it showed no polymorphisms. Phylogenic analysis suggested that Ci-v-Themis-like is an ancestral protein of v-Themis-A and v-Themis-B. Whole mount in situ hybridization revealed that Ci-v-Themis-like mRNA is expressed in the ovary and testis. Western blotting and immunocytochemistry showed the occurrence of Ci-v-Themis-like in developing oocytes and on the VC of mature eggs. Yeast two-hybrid screenings using testis and ovary libraries revealed candidate interacting proteins; among these candidates, we succeeded in identifying several testis-specific proteins, including sperm proteases and coiled-coil-domain-containing proteins. The results suggest that Ci-v-Themis-like and its binding partners are involved in sperm binding to the VC prior to the allorecognition process during C. intestinalis fertilization.

  12. Differential gene regulation by V(IV) and V (V) ions in the branchial sac, intestine, and blood cells of a vanadium-rich ascidian, Ciona intestinalis.

    PubMed

    Kume, Satoshi; Ueki, Tatsuya; Matsuoka, Hiroki; Hamada, Mayuko; Satoh, Nori; Michibata, Hitoshi

    2012-10-01

    Ascidians are hyperaccumulators that have been studied in detail. Proteins and genes involved in the accumulation process have been identified, but regulation of gene expression related to vanadium accumulation remains unknown. To gain insights into the regulation of gene expression by vanadium in a genome-wide manner, we performed a comprehensive study on the effect of excess vanadium ions on a vanadium-rich ascidian, Ciona intestinalis, using a microarray. RT-PCR and enzyme activity assay were performed from the perspective of redox and accumulation of metal ions in each tissue. Glutathione metabolism-related proteins were significantly up-regulated by V(IV) treatment. Several genes involved in the transport of vanadium and protons, such as Nramp and V-ATPase, were significantly up-regulated by V(IV) treatment. We observed significant up-regulation of glutathione synthesis and degradation pathways in the intestine and branchial sac. In blood cells, expression of Ci-Vanabin4, glutathione reductase activity, glutathione levels, and vanadium concentration increased after V(IV) treatment. V(IV) treatment induced significant changes related to vanadium exclusion, seclusion, and redox pathways in the intestine and branchial sac. It also induced an enhancement of the vanadium reduction and accumulation cascade in blood cells. These differential responses in each tissue in the presence of excess vanadium ions suggest that vanadium accumulation and reduction may have regulatory functions. This is the first report on the gene regulation by the treatment of vanadium-rich ascidians with excess vanadium ions. It provided much information for the mechanism of regulation of gene expression related to vanadium accumulation.

  13. The Hemolymph of the ascidian Styela plicata (Chordata-Tunicata) contains heparin inside basophil-like cells and a unique sulfated galactoglucan in the plasma.

    PubMed

    de Barros, Cintia M; Andrade, Leonardo R; Allodi, Silvana; Viskov, Christian; Mourier, Pierre A; Cavalcante, Moisés C M; Straus, Anita H; Takahashi, Helio K; Pomin, Vitor H; Carvalho, Vinicius F; Martins, Marco A; Pavão, Mauro S G

    2007-01-19

    The hemolymph of ascidians (Chordata-Tunicata) contains different types of hemocytes embedded in a liquid plasma. In the present study, heparin and a sulfated heteropolysaccharide were purified from the hemolymph of the ascidian Styela plicata. The heteropolysaccharide occurs free in the plasma, is composed of glucose ( approximately 60%) and galactose ( approximately 40%), and is highly sulfated. Heparin, on the other hand, occurs in the hemocytes, and high performance liquid chromatography of the products formed by degradation with specific lyases revealed that it is composed mainly by the disaccharides DeltaUA(2SO(4))-1-->4-beta-d-GlcN(SO(4)) (39.7%) and DeltaUA(2SO(4))-1-->4-beta-d-GlcN(SO(4))(6SO(4)) (38.2%). Small amounts of the 3-O-sulfated disaccharides DeltaUA(2SO(4))-1-->4-beta-d-GlcN(SO(4))(3SO(4)) (9.8%) and DeltaUA(2SO(4))-1-->4-beta-d-GlcN(SO(4))(3SO(4))(6SO(4)) (3.8%) were also detected. These 3-O-sulfated disaccharides were demonstrated to be essential for the binding of the hemocyte heparin to antithrombin III. Electron microscopy techniques were used to characterize the ultrastructure of the hemocytes and to localize heparin and histamine in these cells. At least five cell types were recognized and classified as univacuolated and multivacuolated cells, amebocytes, hemoblasts, and granulocytes. Immunocytochemistry showed that heparin and histamine co-localize in intracellular granules of only one type of hemocyte, the granulocyte. These results show for the first time that in ascidians, a sulfated galactoglucan circulates free in the plasma, and heparin occurs as an intracellular product of a circulating basophil-like cell.

  14. Trunk lateral cells are neural crest-like cells in the ascidian Ciona intestinalis: insights into the ancestry and evolution of the neural crest.

    PubMed

    Jeffery, William R; Chiba, Takuto; Krajka, Florian Razy; Deyts, Carole; Satoh, Nori; Joly, Jean-Stéphane

    2008-12-01

    Neural crest-like cells (NCLC) that express the HNK-1 antigen and form body pigment cells were previously identified in diverse ascidian species. Here we investigate the embryonic origin, migratory activity, and neural crest related gene expression patterns of NCLC in the ascidian Ciona intestinalis. HNK-1 expression first appeared at about the time of larval hatching in dorsal cells of the posterior trunk. In swimming tadpoles, HNK-1 positive cells began to migrate, and after metamorphosis they were localized in the oral and atrial siphons, branchial gill slits, endostyle, and gut. Cleavage arrest experiments showed that NCLC are derived from the A7.6 cells, the precursors of trunk lateral cells (TLC), one of the three types of migratory mesenchymal cells in ascidian embryos. In cleavage arrested embryos, HNK-1 positive TLC were present on the lateral margins of the neural plate and later became localized adjacent to the posterior sensory vesicle, a staging zone for their migration after larval hatching. The Ciona orthologues of seven of sixteen genes that function in the vertebrate neural crest gene regulatory network are expressed in the A7.6/TLC lineage. The vertebrate counterparts of these genes function downstream of neural plate border specification in the regulatory network leading to neural crest development. The results suggest that NCLC and neural crest cells may be homologous cell types originating in the common ancestor of tunicates and vertebrates and support the possibility that a putative regulatory network governing NCLC development was co-opted to produce neural crest cells during vertebrate evolution.

  15. A new species of photosymbiotic ascidian from the Ryukyu Archipelago, Japan, with remarks on the stability of stigma number in photosymbiotic Diplosoma species.

    PubMed

    Hirose, Euichi; Oka, Atsushi T

    2008-12-01

    Diplosoma variostigmatum sp. nov. is a photosymbiotic ascidian in the family Didemnidae. This species is characterized by the unique pattern of its stigma number, which is often variable within the same zooid, as well as within the same colony. The total number of stigmata per half branchial sac varies from 22 (five, six, six, and five stigmata from the top to bottom rows) to 27 (seven, seven, seven, and six). In contrast, the stigma patterns are constant in D. ooru, D. simile, D. simileguwa, and D. virens. Thus, the stigma number and its stability (or variability) seem to be important as characters for the taxonomy of the photosymbiotic Diplosoma species.

  16. NK4 antagonizes Tbx1/10 to promote cardiac versus pharyngeal muscle fate in the ascidian second heart field.

    PubMed

    Wang, Wei; Razy-Krajka, Florian; Siu, Eric; Ketcham, Alexandra; Christiaen, Lionel

    2013-12-01

    The heart and head muscles share common developmental origins and genetic underpinnings in vertebrates, including humans. Parts of the heart and cranio-facial musculature derive from common mesodermal progenitors that express NKX2-5, ISL1, and TBX1. This ontogenetic kinship is dramatically reflected in the DiGeorge/Cardio-Velo-Facial syndrome (DGS/CVFS), where mutations of TBX1 cause malformations in the pharyngeal apparatus and cardiac outflow tract. Cardiac progenitors of the first heart field (FHF) do not require TBX1 and segregate precociously from common progenitors of the second heart field (SHF) and pharyngeal muscles. However, the cellular and molecular mechanisms that govern heart versus pharyngeal muscle specification within this lineage remain elusive. Here, we harness the simplicity of the ascidian larva to show that, following asymmetric cell division of common progenitors, NK4/NKX2-5 promotes GATAa/GATA4/5/6 expression and cardiac specification in the second heart precursors by antagonizing Tbx1/10-mediated inhibition of GATAa and activation of Collier/Olf/EBF (COE), the determinant of atrial siphon muscle (ASM) specification. Our results uncover essential regulatory connections between the conserved cardio-pharyngeal factor Tbx1/10 and muscle determinant COE, as well as a mutual antagonism between NK4 and Tbx1/10 activities upstream of GATAa and COE. The latter cross-antagonism underlies a fundamental heart versus pharyngeal muscle fate choice that occurs in a conserved lineage of cardio-pharyngeal progenitors. We propose that this basic ontogenetic motif underlies cardiac and pharyngeal muscle development and evolution in chordates.

  17. NK4 Antagonizes Tbx1/10 to Promote Cardiac versus Pharyngeal Muscle Fate in the Ascidian Second Heart Field

    PubMed Central

    Wang, Wei; Razy-Krajka, Florian; Siu, Eric; Ketcham, Alexandra; Christiaen, Lionel

    2013-01-01

    The heart and head muscles share common developmental origins and genetic underpinnings in vertebrates, including humans. Parts of the heart and cranio-facial musculature derive from common mesodermal progenitors that express NKX2-5, ISL1, and TBX1. This ontogenetic kinship is dramatically reflected in the DiGeorge/Cardio-Velo-Facial syndrome (DGS/CVFS), where mutations of TBX1 cause malformations in the pharyngeal apparatus and cardiac outflow tract. Cardiac progenitors of the first heart field (FHF) do not require TBX1 and segregate precociously from common progenitors of the second heart field (SHF) and pharyngeal muscles. However, the cellular and molecular mechanisms that govern heart versus pharyngeal muscle specification within this lineage remain elusive. Here, we harness the simplicity of the ascidian larva to show that, following asymmetric cell division of common progenitors, NK4/NKX2-5 promotes GATAa/GATA4/5/6 expression and cardiac specification in the second heart precursors by antagonizing Tbx1/10-mediated inhibition of GATAa and activation of Collier/Olf/EBF (COE), the determinant of atrial siphon muscle (ASM) specification. Our results uncover essential regulatory connections between the conserved cardio-pharyngeal factor Tbx1/10 and muscle determinant COE, as well as a mutual antagonism between NK4 and Tbx1/10 activities upstream of GATAa and COE. The latter cross-antagonism underlies a fundamental heart versus pharyngeal muscle fate choice that occurs in a conserved lineage of cardio-pharyngeal progenitors. We propose that this basic ontogenetic motif underlies cardiac and pharyngeal muscle development and evolution in chordates. PMID:24311985

  18. Stochasticity in space, persistence in time: genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata

    PubMed Central

    Pineda, Mari-Carmen; Lorente, Beatriz; López-Legentil, Susanna; Palacín, Creu

    2016-01-01

    Spatio-temporal changes in genetic structure among populations provide crucial information on the dynamics of secondary spread for introduced marine species. However, temporal components have rarely been taken into consideration when studying the population genetics of non-indigenous species. This study analysed the genetic structure of Styela plicata, a solitary ascidian introduced in harbours and marinas of tropical and temperate waters, across spatial and temporal scales. A fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) was sequenced from 395 individuals collected at 9 harbours along the NW Mediterranean coast and adjacent Atlantic waters (> 1,200 km range) at two time points 5 years apart (2009 and 2014). The levels of gene diversity were relatively low for all 9 locations in both years. Analyses of genetic differentiation and distribution of molecular variance revealed strong genetic structure, with significant differences among many populations, but no significant differences among years. A weak and marginally significant correlation between geographic distance and gene differentiation was found. Our results revealed spatial structure and temporal genetic homogeneity in S. plicata, suggesting a limited role of recurrent, vessel-mediated transport of organisms among small to medium-size harbours. Our study area is representative of many highly urbanized coasts with dense harbours. In these environments, the episodic chance arrival of colonisers appears to determine the genetic structure of harbour populations and the genetic composition of these early colonising individuals persists in the respective harbours, at least over moderate time frames (five years) that encompass ca. 20 generations of S. plicata. PMID:27366653

  19. Transposon-mediated enhancer detection reveals the location, morphology and development of the cupular organs, which are putative hydrodynamic sensors, in the ascidian Ciona intestinalis.

    PubMed

    Ohta, Naoyuki; Horie, Takeo; Satoh, Nori; Sasakura, Yasunori

    2010-11-01

    The adult of the ascidian Ciona intestinalis has cupular organs, i.e., putative hydrodynamic sensors, at the atrial epithelium. The cupular organ consists of support cells and sensory neurons, and it extends a gelatinous matrix, known as a cupula, toward the atrial cavity. These characteristics are shared with sensory hair cells in the vertebrate inner ear and lateral line neuromasts in fish and amphibians, which suggests an evolutionary link between the cupular organ and these vertebrate hydrodynamic sensors. In the present study, we have isolated and investigated two transposon-mediated enhancer detection lines that showed GFP expression in support cells of the cupular organs. Using the enhancer detection lines and neuron marker transgenic lines, we describe the position, morphology, and development of the cupular organs. Cupular organs were found at the atrial epithelium, but not in the branchial epithelium. We found that cupular organs are also present along the dorsal fold and the gonoducts. The cells lining the pre-atrial opening in juveniles are presumably precursor cells of the cupular organ. To our knowledge, the present study is the first precise description of the ascidian cupular organ, providing evidence that may help to resolve discrepancies among previous studies on the organ.

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

    SciTech Connect

    Mourao, P.A.S. )

    1991-04-09

    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 {sup 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-({sup 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{prime}-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.

  1. Two new species of photosymbiotic ascidians of the genus Diplosoma from the Ryukyu Archipelago, with partial sequences of the COI gene.

    PubMed

    Hirose, Euichi; Oka, Atsushi T; Hirose, Mamiko

    2009-05-01

    Two new species of Diplosoma are described from coral reefs in the Ryukyu Archipelago, Japan: D. watanabei sp. nov. and D. gumavirens sp. nov. Colonies of both species are green due to algal symbionts of Prochloron, which are distributed in the common cloacal cavity. Both species are characterized by the point of emergence of the retractor muscle and a unique combination of stigma numbers among the four rows of the branchial sac. There are three adhesive papillae in the embryos of D. watanabei, as in most ascidian embryos and larvae, whereas the pre-hatching embryos of D. gumavirens sp. nov. posses 12-16 adhesive papillae. Partial sequences of the cytochrome c oxidase subunit I (COI) gene discriminated the new species from each other and from congeners.

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

    SciTech Connect

    Jeffery, W.R. )

    1990-09-01

    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.

  3. A Boolean Function for Neural Induction Reveals a Critical Role of Direct Intercellular Interactions in Patterning the Ectoderm of the Ascidian Embryo

    PubMed Central

    Mochizuki, Atsushi; Satou, Yutaka

    2015-01-01

    A complex system of multiple signaling molecules often produce differential gene expression patterns in animal embryos. In the ascidian embryo, four signaling ligands, Ephrin-A.d (Efna.d), Fgf9/16/20, Admp, and Gdf1/3-r, coordinately induce Otx expression in the neural lineage at the 32-cell stage. However, it has not been determined whether differential inputs of all of these signaling pathways are really necessary. It is possible that differential activation of one of these signaling pathways is sufficient and the remaining signaling pathways are activated in all cells at similar levels. To address this question, we developed a parameter-free method for determining a Boolean function for Otx expression in the present study. We treated activities of signaling pathways as Boolean values, and we also took all possible patterns of signaling gradients into consideration. We successfully determined a Boolean function that explains Otx expression in the animal hemisphere of wild-type and morphant embryos at the 32-cell stage. This Boolean function was not inconsistent with three sensing patterns, which represented whether or not individual cells received sufficient amounts of the signaling molecules. These sensing patterns all indicated that differential expression of Otx in the neural lineage is primarily determined by Efna.d, but not by differential inputs of Fgf9/16/20, Admp, and Gdf1/3-r signaling. To confirm this hypothesis experimentally, we simultaneously knocked-down Admp, Gdf1/3-r, and Fgf9/16/20, and treated this triple morphant with recombinant bFGF and BMP4 proteins, which mimic Fgf9/16/20 and Admp/Gdf1/3-r activity, respectively. Although no differential inputs of Admp, Gdf1/3-r and Fgf9/16/20 signaling were expected under this experimental condition, Otx was expressed specifically in the neural lineage. Thus, direct cell–cell interactions through Efna.d play a critical role in patterning the ectoderm of the early ascidian embryo. PMID:26714026

  4. A Boolean Function for Neural Induction Reveals a Critical Role of Direct Intercellular Interactions in Patterning the Ectoderm of the Ascidian Embryo.

    PubMed

    Ohta, Naoyuki; Waki, Kana; Mochizuki, Atsushi; Satou, Yutaka

    2015-12-01

    A complex system of multiple signaling molecules often produce differential gene expression patterns in animal embryos. In the ascidian embryo, four signaling ligands, Ephrin-A.d (Efna.d), Fgf9/16/20, Admp, and Gdf1/3-r, coordinately induce Otx expression in the neural lineage at the 32-cell stage. However, it has not been determined whether differential inputs of all of these signaling pathways are really necessary. It is possible that differential activation of one of these signaling pathways is sufficient and the remaining signaling pathways are activated in all cells at similar levels. To address this question, we developed a parameter-free method for determining a Boolean function for Otx expression in the present study. We treated activities of signaling pathways as Boolean values, and we also took all possible patterns of signaling gradients into consideration. We successfully determined a Boolean function that explains Otx expression in the animal hemisphere of wild-type and morphant embryos at the 32-cell stage. This Boolean function was not inconsistent with three sensing patterns, which represented whether or not individual cells received sufficient amounts of the signaling molecules. These sensing patterns all indicated that differential expression of Otx in the neural lineage is primarily determined by Efna.d, but not by differential inputs of Fgf9/16/20, Admp, and Gdf1/3-r signaling. To confirm this hypothesis experimentally, we simultaneously knocked-down Admp, Gdf1/3-r, and Fgf9/16/20, and treated this triple morphant with recombinant bFGF and BMP4 proteins, which mimic Fgf9/16/20 and Admp/Gdf1/3-r activity, respectively. Although no differential inputs of Admp, Gdf1/3-r and Fgf9/16/20 signaling were expected under this experimental condition, Otx was expressed specifically in the neural lineage. Thus, direct cell-cell interactions through Efna.d play a critical role in patterning the ectoderm of the early ascidian embryo.

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

    PubMed

    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.

  6. Structural and functional properties of CiNTH, an endonuclease III homologue of the ascidian Ciona intestinalis: critical role of N-terminal region.

    PubMed

    Kato, Seiji; Hashiguchi, Kazunari; Igarashi, Kento; Moriwaki, Takahito; Yonekura, Shin-Ichiro; Zhang-Akiyama, Qiu-Mei

    2012-01-01

    Oxidatively damaged bases in DNA can cause cell death, mutation and/or cancer induction. To overcome such deleterious effects of DNA base oxidation, cells are equipped with base excision repair (BER) initiated by DNA glycosylases. Endonuclease III (Nth), a major DNA glycosylase, mainly excises oxidatively damaged pyrimidines from DNA. The aims of this study were to obtain an overview of the repair mechanism of oxidatively damaged bases and to elucidate the function of BER in maintaining genome stability during embryogenesis and development. In this study, we used the ascidian Ciona intestinalis because at every developmental stage it is possible to observe the phenotype of individuals with DNA damage or mutations. Sequence alignment analysis revealed that the amino acid sequence of Ciona intestinalis Nth homologue (CiNTH) had high homology with those of Escherichia coli, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Caenorhabditis elegans and human Nth homologues. It was evident that two domains, the Helix-hairpin-Helix and 4Fe-4S cluster domains that are critical regions for the Nth activity, are well conserved in CiNTH. CiNTH efficiently complemented the sensitivity of E. coli nth nei mutant to H(2)O(2). CiNTH was bifunctional, with DNA glycosylase and AP lyase activities. It removed thymine glycol, 5-formyluracil and 8-oxoguanine paired with G from DNA via a β-elimination reaction. Interestingly, the N-terminal 44 amino acids were essential for the DNA glycosylase activity of CiNTH.

  7. Nitric oxide affects ERK signaling through down-regulation of MAP kinase phosphatase levels during larval development of the ascidian Ciona intestinalis.

    PubMed

    Castellano, Immacolata; Ercolesi, Elena; Palumbo, Anna

    2014-01-01

    In the ascidian Ciona intestinalis larval development and metamorphosis require a complex interplay of events, including nitric oxide (NO) production, MAP kinases (ERK, JNK) and caspase-3 activation. We have previously shown that NO levels affect the rate of metamorphosis, regulate caspase activity and promote an oxidative stress pathway, resulting in protein nitration. Here, we report that NO down-regulates MAP kinase phosphatases (mkps) expression affecting positively ERK signaling. By pharmacological approach, we observed that the reduction of endogenous NO levels caused a decrease of ERK phosphorylation, whereas increasing levels of NO induced ERK activation. We have also identified the ERK gene network affected by NO, including mpk1, mpk3 and some key developmental genes by quantitative gene expression analysis. We demonstrate that NO induces an ERK-independent down-regulation of mkp1 and mkp3, responsible for maintaining the ERK phosphorylation levels necessary for transcription of key metamorphic genes, such as the hormone receptor rev-erb and the van willebrand protein vwa1c. These results add new insights into the role played by NO during larval development and metamorphosis in Ciona, highlighting the cross-talk between different signaling pathways.

  8. The diatom-derived aldehyde decadienal affects life cycle transition in the ascidian Ciona intestinalis through nitric oxide/ERK signalling.

    PubMed

    Castellano, Immacolata; Ercolesi, Elena; Romano, Giovanna; Ianora, Adrianna; Palumbo, Anna

    2015-03-01

    Polyunsaturated aldehydes (PUAs) are fatty-acid-derived metabolites produced by some microalgae, including different diatom species. PUAs are mainly produced as a wound-activated defence mechanism against microalgal predators or released from senescent cells at the end of a bloom. PUAs, including 2,4-trans-decadienal (DD), induce deleterious effects on embryonic and larval development of several planktonic and benthic organisms. Here, we report on the effects of DD on larval development and metamorphosis of the ascidian Ciona intestinalis. Ciona larval development is regulated by the cross-talking of different molecular events, including nitric oxide (NO) production, ERK activation and caspase 3-dependent apoptosis. We report that treatment with DD at the competence larval stage results in a delay in metamorphosis. DD affects redox balance by reducing total glutathione and NO levels. By biochemical and quantitative gene expression analysis, we identify the NO-signalling network affected by DD, including the upregulation of ERK phosphatase mkp1 and consequent reduction of ERK phosphorylation, with final changes in the expression of downstream ERK target genes. Overall, these results give new insights into the molecular pathways induced in marine organisms after exposure to PUAs during larval development, demonstrating that this aldehyde affects key checkpoints of larval transition from the vegetative to the reproductive life stage.

  9. A pipeline for the systematic identification of non-redundant full-ORF cDNAs for polymorphic and evolutionary divergent genomes: Application to the ascidian Ciona intestinalis

    SciTech Connect

    Gilchrist, Michael J.; Sobral, Daniel; Khoueiry, Pierre; Daian, Fabrice; Laporte, Batiste; Patrushev, Ilya; Matsumoto, Jun; Dewar, Ken; Hastings, Kenneth E. M.; Satou, Yutaka; Lemaire, Patrick; Rothbächer, Ute

    2015-05-27

    Genome-wide resources, such as collections of cDNA clones encoding for complete proteins (full-ORF clones), are crucial tools for studying the evolution of gene function and genetic interactions. Non-model organisms, in particular marine organisms, provide a rich source of functional diversity. Marine organism genomes are, however, frequently highly polymorphic and encode proteins that diverge significantly from those of well-annotated model genomes. The construction of full-ORF clone collections from non-model organisms is hindered by the difficulty of predicting accurately the N-terminal ends of proteins, and distinguishing recent paralogs from highly polymorphic alleles. We also report a computational strategy that overcomes these difficulties, and allows for accurate gene level clustering of transcript data followed by the automated identification of full-ORFs with correct 5'- and 3'-ends. It is robust to polymorphism, includes paralog calling and does not require evolutionary proximity to well annotated model organisms. Here, we developed this pipeline for the ascidian Ciona intestinalis, a highly polymorphic member of the divergent sister group of the vertebrates, emerging as a powerful model organism to study chordate gene function, Gene Regulatory Networks and molecular mechanisms underlying human pathologies. Furthermore, using this pipeline we have generated the first full-ORF collection for a highly polymorphic marine invertebrate. It contains 19,163 full-ORF cDNA clones covering 60% of Ciona coding genes, and full-ORF orthologs for approximately half of curated human disease-associated genes.

  10. Mitochondrial inhibitor sodium azide inhibits the reorganization of mitochondria-rich cytoplasm and the establishment of the anteroposterior axis in ascidian embryo.

    PubMed

    Ishii, Hirokazu; Shirai, Takuma; Makino, Chisato; Nishikata, Takahito

    2014-02-01

    In ascidian eggs, cytoplasmic and cortical reorganization, previously called ooplasmic segregation, occurs in two phases during the first cell cycle. In the second phase of reorganization, the mitochondria-rich cytoplasm (myoplasm) moves to the future posterior side, concurrent with sperm aster migration along the egg cortex. Although this reorganization is the critical step for establishing the anteroposterior axis, its molecular mechanism is not fully understood. In this study, we showed that low concentrations of the mitochondrial inhibitor sodium azide (NaN3 ), which showed the low toxicity in sperm, inhibited the second phase of reorganization without the microtubule depolymerization. In the NaN3 -treated embryo, the sperm aster was not attracted to the cortex and altered its migration pathway; therefore, the myoplasm remained at the vegetal pole. Consequently, the anteroposterior axis was not established. Another mitochondrial inhibitor, oligomycin, did not affect these processes. These results suggest that NaN3 inhibits unknown molecules that are important for the second phase of reorganization. Identifying the target molecule of NaN3 will lead to a molecular understanding of cytoplasmic and cortical reorganization.

  11. A pipeline for the systematic identification of non-redundant full-ORF cDNAs for polymorphic and evolutionary divergent genomes: Application to the ascidian Ciona intestinalis.

    PubMed

    Gilchrist, Michael J; Sobral, Daniel; Khoueiry, Pierre; Daian, Fabrice; Laporte, Batiste; Patrushev, Ilya; Matsumoto, Jun; Dewar, Ken; Hastings, Kenneth E M; Satou, Yutaka; Lemaire, Patrick; Rothbächer, Ute

    2015-08-15

    Genome-wide resources, such as collections of cDNA clones encoding for complete proteins (full-ORF clones), are crucial tools for studying the evolution of gene function and genetic interactions. Non-model organisms, in particular marine organisms, provide a rich source of functional diversity. Marine organism genomes are, however, frequently highly polymorphic and encode proteins that diverge significantly from those of well-annotated model genomes. The construction of full-ORF clone collections from non-model organisms is hindered by the difficulty of predicting accurately the N-terminal ends of proteins, and distinguishing recent paralogs from highly polymorphic alleles. We report a computational strategy that overcomes these difficulties, and allows for accurate gene level clustering of transcript data followed by the automated identification of full-ORFs with correct 5'- and 3'-ends. It is robust to polymorphism, includes paralog calling and does not require evolutionary proximity to well annotated model organisms. We developed this pipeline for the ascidian Ciona intestinalis, a highly polymorphic member of the divergent sister group of the vertebrates, emerging as a powerful model organism to study chordate gene function, Gene Regulatory Networks and molecular mechanisms underlying human pathologies. Using this pipeline we have generated the first full-ORF collection for a highly polymorphic marine invertebrate. It contains 19,163 full-ORF cDNA clones covering 60% of Ciona coding genes, and full-ORF orthologs for approximately half of curated human disease-associated genes.

  12. The central nervous system of the ascidian larva: mitotic history of cells forming the neural tube in late embryonic Ciona intestinalis.

    PubMed

    Cole, Alison G; Meinertzhagen, Ian A

    2004-07-15

    Ascidian larvae develop after an invariant pattern of embryonic cleavage. Fewer than 400 cells constitute the larval central nervous system (CNS), which forms without either extensive migration or cell death. We catalogue the mitotic history of these cells in Ciona intestinalis, using confocal microscopy of whole-mount embryos at stages from neurulation until hatching. The positions of cells contributing to the CNS were reconstructed from confocal image stacks of embryonic nuclei, and maps of successive stages were used to chart the mitotic descent, thereby creating a cell lineage for each cell. The entire CNS is formed from 10th- to 14th-generation cells. Although minor differences exist in cell position, lineage is invariant in cells derived from A-line blastomeres, which form the caudal nerve cord and visceral ganglion. We document the lineage of five pairs of presumed motor neurons within the visceral ganglion: one pair arises from A/A 10.57, and four from progeny of A/A 9.30. The remaining cells of the visceral ganglion are in their 13th and 14th generations at hatching, with most mitotic activity ceasing around 85% of embryonic development. Of the approximately 330 larval cells previously reported in the CNS of Ciona, we document the lineage of 226 that derive predominantly from A-line blastomeres.

  13. The diatom-derived aldehyde decadienal affects life cycle transition in the ascidian Ciona intestinalis through nitric oxide/ERK signalling

    PubMed Central

    Castellano, Immacolata; Ercolesi, Elena; Romano, Giovanna; Ianora, Adrianna; Palumbo, Anna

    2015-01-01

    Polyunsaturated aldehydes (PUAs) are fatty-acid-derived metabolites produced by some microalgae, including different diatom species. PUAs are mainly produced as a wound-activated defence mechanism against microalgal predators or released from senescent cells at the end of a bloom. PUAs, including 2,4-trans-decadienal (DD), induce deleterious effects on embryonic and larval development of several planktonic and benthic organisms. Here, we report on the effects of DD on larval development and metamorphosis of the ascidian Ciona intestinalis. Ciona larval development is regulated by the cross-talking of different molecular events, including nitric oxide (NO) production, ERK activation and caspase 3-dependent apoptosis. We report that treatment with DD at the competence larval stage results in a delay in metamorphosis. DD affects redox balance by reducing total glutathione and NO levels. By biochemical and quantitative gene expression analysis, we identify the NO-signalling network affected by DD, including the upregulation of ERK phosphatase mkp1 and consequent reduction of ERK phosphorylation, with final changes in the expression of downstream ERK target genes. Overall, these results give new insights into the molecular pathways induced in marine organisms after exposure to PUAs during larval development, demonstrating that this aldehyde affects key checkpoints of larval transition from the vegetative to the reproductive life stage. PMID:25788553

  14. Valosin-containing protein/p97 interacts with sperm-activating and sperm-attracting factor (SAAF) in the ascidian egg and modulates sperm-attracting activity.

    PubMed

    Kondoh, Eri; Konno, Aru; Inaba, Kazuo; Oishi, Tohru; Murata, Michio; Yoshida, Manabu

    2008-10-01

    Sperm chemotaxis toward an egg is observed in many animals, and the control of sperm-attracting activity is thought to play an important role in ensuring fertilization. However, the mechanism underlying the release of a sperm attractant from an egg is still obscure. In this study, we examined the systems involved in the release of sperm-activating and sperm-attracting factor (SAAF), which is the sperm attractant of the ascidian Ciona intestinalis. Here, we show that the egg acquires sperm-attracting activity after germinal vesicle breakdown. Further, since the cytoplasmic extracts of immature oocytes exhibit no sperm-attracting activity, the SAAF in oocytes may be activated after germinal vesicle breakdown. We found 13 SAAF-binding proteins in an egg plasma membrane extract and identified five proteins by proteomic analysis: valosin-containing protein (VCP)/p97, proteasome alpha 2 subunit, MGC97756 protein, proteasome subunit Y, and beta-tubulin. In particular, the interaction between VCP/p97 and SAAF was confirmed by a pull-down assay. VCP/p97 is initially localized in the germinal vesicle, and during oocyte maturation, it shifts to the endoplasmic reticulum in the cortical regions. Thus, VCP/p97 is a potential modulator of SAAF release from the egg.

  15. A pipeline for the systematic identification of non-redundant full-ORF cDNAs for polymorphic and evolutionary divergent genomes: Application to the ascidian Ciona intestinalis

    DOE PAGES

    Gilchrist, Michael J.; Sobral, Daniel; Khoueiry, Pierre; ...

    2015-05-27

    Genome-wide resources, such as collections of cDNA clones encoding for complete proteins (full-ORF clones), are crucial tools for studying the evolution of gene function and genetic interactions. Non-model organisms, in particular marine organisms, provide a rich source of functional diversity. Marine organism genomes are, however, frequently highly polymorphic and encode proteins that diverge significantly from those of well-annotated model genomes. The construction of full-ORF clone collections from non-model organisms is hindered by the difficulty of predicting accurately the N-terminal ends of proteins, and distinguishing recent paralogs from highly polymorphic alleles. We also report a computational strategy that overcomes these difficulties,more » and allows for accurate gene level clustering of transcript data followed by the automated identification of full-ORFs with correct 5'- and 3'-ends. It is robust to polymorphism, includes paralog calling and does not require evolutionary proximity to well annotated model organisms. Here, we developed this pipeline for the ascidian Ciona intestinalis, a highly polymorphic member of the divergent sister group of the vertebrates, emerging as a powerful model organism to study chordate gene function, Gene Regulatory Networks and molecular mechanisms underlying human pathologies. Furthermore, using this pipeline we have generated the first full-ORF collection for a highly polymorphic marine invertebrate. It contains 19,163 full-ORF cDNA clones covering 60% of Ciona coding genes, and full-ORF orthologs for approximately half of curated human disease-associated genes.« less

  16. The occurrence of the colonial ascidian Didemnum sp. on Georges Bank gravel habitat: ecological observations and potential effects on groundfish and scallop fisheries

    USGS Publications Warehouse

    Valentine, P.C.; Collie, J.S.; Reid, R.N.; Asch, R.G.; Guida, V.G.; Blackwood, D.S.

    2007-01-01

    The colonial ascidian Didemnum sp. is present on the Georges Bank fishing grounds in a gravel habitat where the benthic invertebrate fauna has been monitored annually since 1994. The species was not noted before 2002 when large colonies were first observed; and by 2003 and 2004 it covered large areas of the seabed at some locations. The latest survey in 2005 documented the tunicate's presence in two gravel areas that total more than 67 nm2 (230 km2). The affected area is located on the Northern Edge of the bank in United States waters near the U.S./Canada boundary ( Fig. 1). This is the first documented offshore occurrence of a species that has colonized eastern U.S. coastal waters from New York to Maine during the past 15–20 years ( U.S. Geological Survey, 2006). Video imagery shows colonies coalescing to form large mats that cover more than 50% of the seabed along some video/photo transects. The affected area is an immobile pebble and cobble pavement that lies at water depths of 40 to 65 m where strong semidiurnal tidal currents reach speeds of 1 to 2 kt (50–100 cm/s). The water column is mixed year round, ensuring a constant supply of nutrients to the seabed. Annual temperatures range from 4 to 15 °C ( Mountain and Holzwarth, 1989). The gravel areas are bounded by sand ridges whose mobile surfaces are moved daily by the strong tidal currents. Studies commenced here in 1994 to characterize the gravel habitat and to document the effects of fishing disturbance on it ( Collie et al., 2005).

  17. Evolution of the Chordate Regeneration Blastema: Differential Gene Expression and Conserved Role of Notch Signaling During Siphon Regeneration in the Ascidian Ciona

    PubMed Central

    Hamada, Mayuko; Goricki, Spela; Byerly, Mardi S.; Satoh, Noriyuki; Jeffery, William R.

    2015-01-01

    The regeneration of the oral siphon (OS) and other distal structures in the ascidian Ciona intestinalis occurs by epimorphosis involving the formation of a blastema of proliferating cells. Despite the longstanding use of Ciona as a model in molecular developmental biology, regeneration in this system has not been previously explored by molecular analysis. Here we have employed microarray analysis and quantitative real time RT-PCR to identify genes with differential expression profiles during OS regeneration. The majority of differentially expressed genes were downregulated during OS regeneration, suggesting roles in normal growth and homeostasis. However, a subset of differentially expressed genes was upregulated in the regenerating OS, suggesting functional roles during regeneration. Among the upregulated genes were key members of the Notch signaling pathway, including those encoding the delta and jagged ligands, two fringe modulators, and to a lesser extent the notch receptor. In situ hybridization showed a complementary pattern of delta1 and notch gene expression in the blastema of the regenerating OS. Chemical inhibition of the Notch signaling pathway reduced the levels of cell proliferation in the branchial sac, a stem cell niche that contributes progenitor cells to the regenerating OS, and in the OS regeneration blastema, where siphon muscle fibers eventually re-differentiate. Chemical inhibition also prevented the replacement of oral siphon pigment organs, sensory receptors rimming the entrance of the OS, and siphon muscle fibers, but had no effects on the formation of the wound epidermis. Since Notch signaling is involved in the maintenance of proliferative activity in both the Ciona and vertebrate regeneration blastema, the results suggest a conserved evolutionary role of this signaling pathway in chordate regeneration. The genes identified in this investigation provide the foundation for future molecular analysis of OS regeneration. PMID:26206613

  18. The colonial ascidian Didemnum sp. A: current distribution, basic biology and potential threat to marine communities of the northeast and west coasts of North America

    USGS Publications Warehouse

    Bullard, S.G.; Lambert, G.; Carman, M.R.; Byrnes, J.; Whitlatch, R.B.; Ruiz, G.; Miller, R.J.; Harris, L.; Valentine, P.C.; Collie, J.S.; Pederson, J.; McNaught, D.C.; Cohen, A.N.; Asch, R.G.; Dijkstra, J.; Heinonen, K.

    2007-01-01

    Didemnum sp. A is a colonial ascidian with rapidly expanding populations on the east and west coasts of North America. The origin of Didemum sp. A is unknown. Populations were first observed on the northeast coast of the U.S. in the late 1980s and on the west coast during the 1990s. It is currently undergoing a massive population explosion and is now a dominant member of many subtidal communities on both coasts. To determine Didemnum sp. A's current distribution, we conducted surveys from Maine to Virginia on the east coast and from British Columbia to southern California on the west coast of the U.S. between 1998 and 2005. In nearshore locations Didemnum sp. A currently ranges from Eastport, Maine to Shinnecock Bay, New York on the east coast. On the west coast it has been recorded from Humboldt Bay to Port San Luis in California, several sites in Puget Sound, Washington, including a heavily fouled mussel culture facility, and several sites in southwestern British Columbia on and adjacent to oyster and mussel farms. The species also occurs at deeper subtidal sites (up to 81 m) off New England, including Georges, Stellwagen and Tillies Banks. On Georges Bank numerous sites within a 230 km2 area are 50–90% covered by Didemnum sp. A; large colonies cement the pebble gravel into nearly solid mats that may smother infaunal organisms. These observations suggest that Didemnum sp. A has the potential to alter marine communities and affect economically important activities such as fishing and aquaculture.

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

    PubMed

    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.

  20. Molecular and functional characterization of cionin receptors in the ascidian, Ciona intestinalis: the evolutionary origin of the vertebrate cholecystokinin/gastrin family.

    PubMed

    Sekiguchi, Toshio; Ogasawara, Michio; Satake, Honoo

    2012-04-01

    Cholecystokinin (CCK) and gastrin are vertebrate brain-gut peptides featured by a sulfated tyrosine residue and a C-terminally amidated tetrapeptide consensus sequence. Cionin, identified in the ascidian, Ciona intestinalis, the closest species to vertebrates, harbors two sulfated tyrosines and the CCK/gastrin consensus tetrapeptide sequence. While a putative cionin receptor, cior, was cloned, the ligand-receptor relationship between cionin and CioR remains unidentified. Here, we identify two cionin receptors, CioR1 and CioR2, which are the aforementioned putative cionin receptor and its novel paralog respectively. Phylogenetic analysis revealed that CioRs are homologous to vertebrate CCK receptors (CCKRs) and diverged from a common ancestor in the Ciona-specific lineage. Cionin activates intracellular calcium mobilization in cultured cells expressing CioR1 or CioR2. Monosulfated and nonsulfated cionin exhibited less potent or no activity, indicating that CioRs possess pharmacological features similar to the vertebrate CCK-specific receptor CCK1R, rather than its subtype CCK2R, given that a sulfated tyrosine in CCK is required for binding to CCK1R, but not to CCK2R. Collectively, the present data reveal that CioRs share a common ancestor with vertebrate CCKRs and indicate that CCK and CCK1R form the ancestral ligand-receptor pair in the vertebrate CCK/gastrin system. Cionin is expressed in the neural complex, digestive organs, oral siphon and atrial siphons, whereas the expression of ciors was detected mainly in these tissues and the ovary. Furthermore, cioninergic neurons innervate both of the siphons. These results suggest that cionin is involved in the regulation of siphonal functions.

  1. Evidence by a voltage clamp study of an electrically mediated block to polyspermy in the egg of the ascidian Phallusia mammillata.

    PubMed

    Goudeau, H; Depresle, Y; Rosa, A; Goudeau, M

    1994-12-01

    Eggs of the ascidian Phallusia mammillata were voltage clamped (from -100 to +60 mV) and inseminated with a low or heavy sperm concentration. From inseminations with low sperm concentration (1 x 10(6) sp/ml), we found that fertilization currents occurred between -100 and +40 mV: they were always inward and displayed an analogous pattern whatever the clamped voltage. We established that the percentages of inseminated eggs that produced a fertilization current varied as a function of the clamped voltage. These percentages were not statistically different from 100% at clamped voltages between -100 and -30 mV, they decreased to 68 and 56% at clamped Vm of -10 and 0 mV, respectively, but were not statistically different from 0% at clamped Vm between +10 and +40 mV. We never obtained any egg electrical response at a clamped voltage of +50 mV. Almost all eggs (96%) which responded electrically were penetrated by one or several spermatozoa. These eggs were resuming meiosis (81 to 50%) at values of clamped Vm between -100 and 0 mV, respectively. At clamped Vm between +10 and +50 mV, the percentages of eggs resuming meiosis were not statistically different from 0. These results indicate that in P. mammillata eggs, the occurrence of an electrical response is voltage dependent and consequently that the initial depolarizing shift of the fertilization potential constitutes a fast block to polyspermy. However, in this species, the sperm penetration is not voltage dependent, since it occurred at clamped Vm from -100 to +40 mV. On the other hand, when eggs were clamped from -100 to +60 mV and inseminated with a heavy sperm concentration (2 x 10(7) sp/ml), the curves expressing, respectively, the percentages of eggs which responded electrically, the percentages of eggs which were penetrated by one or several spermatozoa, and the percentages of eggs resuming meiosis, as functions of the clamped Vm, were shifted by approximately 35 mV toward more positive voltages, compared to the

  2. 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.

    PubMed

    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.

  3. A new structural motif for biological iron: iron K-edge XAS reveals a [Fe4-mu-(OR)5(OR)(9-10)] cluster in the ascidian Perophora annectens.

    PubMed

    Frank, Patrick; DeTomaso, Anthony; Hedman, Britt; Hodgson, Keith O

    2006-05-15

    The Phlebobranch ascidian Perophora annectens surprisingly exhibited a biological Fe/V ratio of approximately 15:1 on multichannel X-ray fluorescence analysis of two independent collections of organisms. Iron K-edge X-ray absorption spectroscopy (XAS) indicated a single form of iron. The XAS K-edge of the first collection of blood cells was shifted approximately +1 eV relative to that of the second, indicating redox activity with average iron oxidation states of 2.67+ and 2.60+. The first-derivative iron XAS K-edge features at 7120.5, 7124, and 7128 eV resembled the XAS of magnetite but not of ferritin or of dissolved Fe(II) or Fe(III). Pseudo-Voigt fits to blood-cell iron K-edge XAS spectra yielded 12.4 integrated units of preedge intensity, indicating a noncentrosymmetric environment. The non-phase-corrected extended X-ray absorption fine structure (EXAFS) Fourier transform spectrum showed a first-shell O/N peak at 1.55 angstroms and an intense Fe-Fe feature at 2.65 angstroms. Fits to the EXAFS required a split first shell with two O at 1.93 angstroms and three O at 2.07 angstroms, consistent with terminal and bridging alkoxide ligands, respectively. More distant shells included three C at 2.87 angstroms, two Fe at 3.08 angstroms, three O at 3.29 angstroms, and one Fe at 3.8 angstroms. Structural models consistent with these findings include a [Fe4(OR)13](2-/3-) broken-edged Fe4O5 cuboid or a [Fe4(OR)14](3-/4-) "Jacob's ladder" with three edge-fused Fe2(OR)2 rhombs. Either of these models represents an entirely new structural motif for biological iron. Vanadium domination of blood-cell metals cannot be a defining trait of Phlebobranch tunicates so long as P. annectens is included among them.

  4. Determination of toxic heavy metals in Echinodermata and Chordata species from South Korea.

    PubMed

    Choi, Ji Yeon; Habte, Girum; Khan, Naeem; Nho, Eun Yeong; Hong, Joon Ho; Choi, Hoon; Park, Kyung Su; Kim, Kyong Su

    2014-01-01

    This study aimed at analysing concentrations of heavy metals including arsenic, lead, cadmium, aluminium and mercury in commonly consumed seafood species belonging to Echinodermata (Anthocidaris crassispina and Stichopus japonicus) and Chordata (Halocynthia roretzi and Styela plicata). The samples were digested by a microwave system and analysed for As, Cd and Pb by inductively coupled plasma mass spectrometer, for Al by inductively coupled plasma-optical emission spectrometer and Hg by Direct Mercury Analyser. The analytical method was validated by determining sensitivity, linearity, precision, spiking recoveries and analysis of the Standard Reference Material (SRM) NIST 1566-b, an Oyster Tissue. Results showed considerably higher accumulation of Al and As in analysed samples, compared to Pb and Cd, while Hg had the lowest contamination. On comparison, the obtained results with the recommended standards by the Food and Agriculture Organization, European Commission and Ministry of Food and Drug Safety of Korea, it was concluded that the analysed seafoods were safe and thus would not pose a threat to consumers.

  5. Molecular systematics of marine gregarine apicomplexans from Pacific tunicates, with descriptions of five novel species of Lankesteria.

    PubMed

    Rueckert, Sonja; Wakeman, Kevin C; Jenke-Kodama, Holger; Leander, Brian S

    2015-08-01

    The eugregarines are a group of apicomplexan parasites that mostly infect the intestines of invertebrates. The high level of morphological variation found within and among species of eugregarines makes it difficult to find consistent and reliable traits that unite even closely related lineages. Based mostly on traits observed with light microscopy, the majority of described eugregarines from marine invertebrates has been classified into a single group, the Lecudinidae. Our understanding of the overall diversity and phylogenetic relationships of lecudinids is very poor, mainly because only a modest amount of exploratory research has been done on the group and very few species of lecudinids have been characterized at the molecular phylogenetic level. In an attempt to understand the diversity of marine gregarines better, we surveyed lecudinids that infect the intestines of Pacific ascidians (i.e. sea squirts) using ultrastructural and molecular phylogenetic approaches; currently, these species fall within one genus, Lankesteria. We collected lecudinid gregarines from six ascidian host species, and our data demonstrated that each host was infected by a different species of Lankesteria: (i) Lankesteria hesperidiiformis sp. nov., isolated from Distaplia occidentalis, (ii) Lankesteria metandrocarpae sp. nov., isolated from Metandrocarpa taylori, (iii) Lankesteria halocynthiae sp. nov., isolated from Halocynthia aurantium, (iv) Lankesteria herdmaniae sp. nov., isolated from Herdmania momus, (v) Lankesteria cf. ritterellae, isolated from Ritterella rubra, and (vi) Lankesteria didemni sp. nov., isolated from Didemnum vexillum. Visualization of the trophozoites with scanning electron microscopy showed that four of these species were covered with epicytic folds, whereas two of the species were covered with a dense pattern of epicytic knobs. The molecular phylogenetic data suggested that species of Lankesteria with surface knobs form a clade that is nested within a paraphyletic

  6. Transcriptome dynamics in early embryos of the ascidian, Ciona intestinalis.

    PubMed

    Matsuoka, Terumi; Ikeda, Tatsuro; Fujimaki, Kotaro; Satou, Yutaka

    2013-12-15

    Maternally provided mRNAs and proteins direct early development and activate the zygotic genome. Using microarrays, we examined the dynamics of transcriptomes during the early development of a basal chordate, Ciona intestinalis. Microarray analysis of unfertilized eggs, as well as 8-, and 16- and 32-cell embryos revealed that nearly half of the genes encoded in the genome were expressed maternally, and that approximately only one-fourth of these genes were expressed at similar levels among eggs obtained from different individuals. Genes encoding proteins involved in protein phosphorylation were enriched in this latter group. More than 90% of maternal RNAs were not reduced before the 16-cell stage when the zygotic developmental program begins. Additionally we obtained gene expression profiles of individual blastomeres from the 8- and 16-cell embryos. On the basis of these profiles, we concluded that the posterior-most localization, which has been reported for over 20 different transcripts, is the only major localization pattern of maternal transcripts. Our data also showed that maternal factors establish only nine distinct patterns of zygotic gene expression at the 16-cell stage. Therefore, one of the main developmental functions of maternally supplied information is to establish these nine distinct expression patterns in the 16-cell embryo. The dynamics of transcriptomes in early-stage embryos provides a foundation for studying how maternal information starts the zygotic program.

  7. Rheological properties and molecular structure of tunicate cellulose in LiCl/1,3-dimethyl-2-imidazolidinone.

    PubMed

    Tamai, Nobutake; Tatsumi, Daisuke; Matsumoto, Takayoshi

    2004-01-01

    Solution properties and molecular structure of tunicate cellulose (TC), an animal cellulose from Halocynthia roretzi, were investigated in terms of rheological and dilute solution properties. The solvent used is 8 wt % LiCl/1,3-dimethyl-2-imidazolidinone (DMI). A solution of dissolving pulp (DP), derived from plant, was also used for comparison. The weight-average molecular weight, Mw, and the limiting viscosity number, [eta], of the TC were evaluated to be 413 x 10(6) and 2645 mL/g, respectively. The TC solution showed the same concentration dependence of GN (GN=5.49 x 10(6)phiw(2.1)4 Pa; phiw: weight fraction of cellulose in solution; GN: plateau modulus) as the DP solution and, moreover, also as the solution of cotton linter (CC) in 8 wt % LiCl/N,N-dimethylacetamide (DMAc). This exponent of 2.1(4) indicates that network structure by entanglements was formed in these solutions. According to the theory of Fetters et al., moreover, such identity means that all of these celluloses have the identical chain structure though their biological origins are far different. On the other hand, the phiw-dependence of eta0-etas (eta0=zero shear rate viscosity of solution; etas=solvent viscosity) was different between the TC and the DP solution in the semidilute regime: the TC solution exhibited eta0-etas proportional, variant phiw(7.5) and the DP solution eta0-etas proportional, variant phiw4. According to the theory of Doi-Edwards, this exponent of 4 (the DP solution) indicates that the DP behaves as flexible polymers in the solution. In contrast, the dependence for the TC solution seems unexplainable on the basis of molecular theories. This difference probably signifies the difference in the relaxation process or mechanism in entanglement systems.

  8. Evaluation of drug toxicity profiles based on the phenotypes of ascidian Ciona intestinalis.

    PubMed

    Mizotani, Yuji; Itoh, Shun; Hotta, Kohji; Tashiro, Etsu; Oka, Kotaro; Imoto, Masaya

    2015-08-07

    In vivo toxicity evaluation using model organisms is an important step for the development of new drugs. Here, we report that Ciona intestinalis, a chordate invertebrate, is beneficial to drug toxicity evaluation for the following reasons: rapid embryonic and larval development, resemblance to vertebrates, ease of management, low cost, transparent body, and low risk of ethical issues. The dynamic phenotypic change of Ciona larvae during metamorphosis prompted us to examine the effect of cytotoxic drugs on its development by quantifying six toxicity endpoints: degenerated tail size, ampulla length, rotation of body axis, stomach size, heart rate, and body size. As a result, mitochondrial respiratory inhibitors, tubulin polymerization/depolymerization inhibitors, or DNA/RNA synthesis inhibitors showed distinct toxicity profiles against these six endpoints, but drugs with the same targets showed a similar toxicity profile in Ciona. Our results suggest Ciona is an effective animal model for profiling drug toxicity and exploring the mechanisms of drugs with unknown targets.

  9. Genomewide gene-associated microsatellite markers for the model invasive ascidian, Ciona intestinalis species complex.

    PubMed

    Lin, Yaping; Chen, Yiyong; Xiong, Wei; Zhan, Aibin

    2016-05-01

    The vase tunicate, Ciona intestinalis species complex, has become a good model for ecological and evolutionary studies, especially those focusing on microevolution associated with rapidly changing environments. However, genomewide genetic markers are still lacking. Here, we characterized a large set of genomewide gene-associated microsatellite markers for C. intestinalis spA (=C. robusta). Bioinformatic analysis identified 4654 microsatellites from expressed sequence tags (ESTs), 2126 of which successfully assigned to chromosomes were selected for further analysis. Based on the distribution evenness on chromosomes, function annotation and suitability for primer design, we chose 545 candidate microsatellites for further characterization. After amplification validation and variation assessment, 218 loci were polymorphic in at least one of the two populations collected from the coast of Arenys de Mar, Spain (N = 24-48), and Cape Town, South Africa (N = 24-33). The number of alleles, observed heterozygosity and expected heterozygosity ranged from 2 to 11, 0 to 0.833 and 0.021 to 0.818, and from 2 to 10, 0 to 0.879 and 0.031 to 0.845 for the Spanish and African populations, respectively. When all microsatellites were tested for cross-species utility, only 60 loci (25.8%) could be successfully amplified and all loci were polymorphic in C. intestinalis spB. A high level of genomewide polymorphism is likely responsible for the low transferability. The large set of microsatellite markers characterized here is expected to provide a useful genomewide resource for ecological and evolutionary studies using C. intestinalis as a model.

  10. Antimalarial activity from three ascidians: an exploration of different marine invertebrate phyla.

    PubMed

    Mendiola, Judith; Hernández, Hilda; Sariego, Idalia; Rojas, Lázara; Otero, Anabel; Ramírez, Angel; Chávez, María de Los Angeles; Payrol, Juan Abreu; Hernández, Aida

    2006-10-01

    Recent research suggests that marine organisms may produce compounds with activity against malaria parasites. Of a total of 27 aqueous extracts from different marine species, collected on the northwest Cuban coast, 20 were considered as showing no significant activity against Plasmodium falciparum F32, with minimum inhibitory concentrations (MIC) >500 microg/ml, while seven extracts (MIC < or =500 microg/ml) were selected for further investigation by determining their selectivity indices and in vivo antimalarial activity. Three species of tunicates were chosen, as more than 50% reduction of P. berghei parasitaemia was produced after administration of 250 or 500 mg/kg of their crude extracts into infected mice. The aqueous extracts of Microcosmus goanus, Ascidia sydneiensis and Phallusia nigra were partitioned between water and n-butanol; the organic phases inhibited P. falciparum growth by 50% at concentrations of 17.5 microg/ml, 20.9 microg/ml and 29.4 microg/ml respectively. In general, these results are similar to those of most ethnobotanical surveys. Further chemical studies are being undertaken in order to isolate new antimalarial compounds from these Caribbean tunicates.

  11. Amphioxus and ascidian Dmbx homeobox genes give clues to the vertebrate origins of midbrain development.

    PubMed

    Takahashi, Tokiharu; Holland, Peter W H

    2004-07-01

    The ancestral chordate neural tube had a tripartite structure, comprising anterior, midbrain-hindbrain boundary (MHB) and posterior regions. The most anterior region encompasses both forebrain and midbrain in vertebrates. It is not clear when or how the distinction between these two functionally and developmentally distinct regions arose in evolution. Recently, we reported a mouse PRD-class homeobox gene, Dmbx1, expressed in the presumptive midbrain at early developmental stages, and the hindbrain at later stages, with exclusion from the MHB. This gene provides a route to investigate the evolution of midbrain development. We report the cloning, genomic structure, phylogeny and embryonic expression of Dmbx genes from amphioxus and from Ciona, representing the two most closely related lineages to the vertebrates. Our analyses show that Dmbx genes form a distinct, ancient, homeobox gene family, with highly conserved sequence and genomic organisation, albeit more divergent in Ciona. In amphioxus, no Dmbx expression is observed in the neural tube, supporting previous arguments that the MHB equivalent region has been secondarily modified in evolution. In Ciona, the CiDmbx gene is detected in neural cells caudal to Pax2/5/8-positive cells (MHB homologue), in the Hox-positive region, but, interestingly, not in any cells rostral to them. These results suggest that a midbrain homologue is missing in Ciona, and argue that midbrain development is a novelty that evolved specifically on the vertebrate lineage. We discuss the evolution of midbrain development in relation to the ancestry of the tripartite neural ground plan and the origin of the MHB organiser.

  12. A Maternal System Initiating the Zygotic Developmental Program through Combinatorial Repression in the Ascidian Embryo

    PubMed Central

    Oda-Ishii, Izumi; Kubo, Atsushi; Kari, Willi; Suzuki, Nobuhiro; Rothbächer, Ute

    2016-01-01

    Maternal factors initiate the zygotic developmental program in animal embryos. In embryos of the chordate, Ciona intestinalis, three maternal factors—Gata.a, β-catenin, and Zic-r.a—are required to establish three domains of gene expression at the 16-cell stage; the animal hemisphere, vegetal hemisphere, and posterior vegetal domains. Here, we show how the maternal factors establish these domains. First, only β-catenin and its effector transcription factor, Tcf7, are required to establish the vegetal hemisphere domain. Second, genes specifically expressed in the posterior vegetal domain have additional repressive cis-elements that antagonize the activity of β-catenin/Tcf7. This antagonizing activity is suppressed by Zic-r.a, which is specifically localized in the posterior vegetal domain and binds to DNA indirectly through the interaction with Tcf7. Third, Gata.a directs specific gene expression in the animal hemisphere domain, because β-catenin/Tcf7 weakens the Gata.a-binding activity for target sites through a physical interaction in the vegetal cells. Thus, repressive regulation through protein-protein interactions among the maternal transcription factors is essential to establish the first distinct domains of gene expression in the chordate embryo. PMID:27152625

  13. Functions of a GnRH receptor heterodimer of the ascidian, Ciona intestinalis.

    PubMed

    Sakai, T; Aoyama, M; Kusakabe, T; Tsuda, M; Satake, H

    2008-01-01

    Gonadotropin-releasing hormone (GnRH) is a ten-amino acid peptide hormone that plays pivotal roles in reproduction in vertebrates and octopus. Recently, six GnRH forms (t-GnRH-3-8) and four GnRH receptor subtypes (Ci-GnRHR-1-4) were identified in the protochordate, Ciona intestinalis. In this study, we show the functional modulation of Ci-GnRHR-1 via heterodimerization with the orphan receptor subtype, Ci-GnRHR-4. The dimerization between Ci-GnRHR-1 and R-4 was detected by co-immunoprecipitation and immunoblot analysis. Binding assays confirmed the binding of t-GnRHs to Ci-GnRHR-1 but not to R-4, and verified no alternation in ligand-binding affinity between Ci-GnRHR-1 homodimer and Ci-GnRHRI&4 heterodimer. The heterodimer was found to stimulate the elevation of intracellular calcium, time-extension of ERK phosphorylation, and up-regulation of cell proliferation, all in a ligand specific manner, compared with the Ci-GnRHR-1 homodimer. In combination, these results indicated that Ci-GnRHR-4 is not an inactive receptor, but a modulatory factor for Ci-GnRHR-1 in C. intestinalis.

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

    PubMed

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

    2013-09-15

    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.

  15. Studies on Japanese botryllid ascidians. V. A new species of the genus Botrylloides very similar to Botrylloides simodensis in morphology.

    PubMed

    Atsumi, Masako O; Saito, Yasunori

    2011-07-01

    Botrylloides simodensis, belonging to the family Botryllidae, is a common species on the rocky shore around Shimoda. Since this species was first reported in 1981, it has been noticed that some B. simodensis colonies have distinctly different ground colors and color patterns from colonies including type specimens (holotype and all of paratypes) of B. simodensis. However, as there is no remarkable difference among them in morphology other than the colonial colors and color patterns, they have been considered to belong to the same species. In the present work, colonies of B. simodensis sensu lato were divided into three groups, two major and one minor, based on their color-morphs and periods of sexual reproduction. In one of the major groups, B. simodensis sensu strict, the period of sexual reproduction was limited from July to September, as shown in the original description. The other major group engaged in sexual reproduction for much longer than the former group, and they frequently made clusters of vascular vessels and underwent vascular budding. Therefore, the group with the long period of sexual reproduction was described as a new species of the genus Botrylloides here. In addition, phylogenetic analysis based on mtDNA sequences of these groups indicated that each group had a peculiar sequence, and that they were genetically separated.

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

    PubMed

    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.

  17. Cell lineage and cis-regulation for a unique GABAergic/glycinergic neuron type in the larval nerve cord of the ascidian Ciona intestinalis.

    PubMed

    Nishitsuji, Koki; Horie, Takeo; Ichinose, Aoi; Sasakura, Yasunori; Yasuo, Hitoyoshi; Kusakabe, Takehiro G

    2012-02-01

    The tunicate Ciona intestinalis larva has a simple central nervous system (CNS), consisting of fewer than 400 cells, which is homologous to the vertebrate CNS. Recent studies have revealed neuronal types and networks in the larval CNS of C. intestinalis, yet their cell lineage and the molecular mechanism by which particular types of neurons are specified and differentiate remain poorly understood. Here, we report cell lineage origin and a cis-regulatory module for the anterior caudal inhibitory neurons (ACINs), a putative component of the central pattern generator regulating swimming locomotion. The vesicular GABA⁄ glycine transporter gene Ci-VGAT, a specific marker for GABAergic ⁄ glycinergic neurons, is expressed in distinct sets of neurons, including ACINs of the tail nerve cord and others in the brain vesicle and motor ganglion. Comparative genomics analysis between C. intestinalis and Ciona savignyi and functional analysis in vivo identified the cis-regulatory module responsible for Ci-VGAT expression in ACINs. Our cell lineage analyses inferred that ACINs derive from A11.116 cells, which have been thought to solely give rise to glial ependymal cells of the lateral wall of the nerve cord. The present findings will provide a solid basis for future studies addressing the molecular mechanism underlying specification of ACINs, which play a critical role in controlling larval locomotion

  18. Application of the cis-regulatory region of a heat-shock protein 70 gene to heat-inducible gene expression in the ascidian Ciona intestinalis.

    PubMed

    Kawaguchi, Akane; Utsumi, Nanami; Morita, Maki; Ohya, Aya; Wada, Shuichi

    2015-01-01

    Temporally controlled induction of gene expression is a useful technique for analyzing gene function. To make such a technique possible in Ciona intestinalis embryos, we employed the cis-regulatory region of the heat-shock protein 70 (HSP70) gene Ci-HSPA1/6/7-like for heat-inducible gene expression in C. intestinalis embryos. We showed that Ci-HSPA1/6/7-like becomes heat shock-inducible by the 32-cell stage during embryogenesis. The 5'-upstream region of Ci-HSPA1/6/7-like, which contains heat-shock elements indispensable for heat-inducible gene expression, induces the heat shock-dependent expression of a reporter gene in the whole embryo from the 32-cell to the middle gastrula stages and in progressively restricted areas of embryos in subsequent stages. We assessed the effects of heat-shock treatments in different conditions on the normality of embryos and induction of transgene expression. We evaluated the usefulness of this technique through overexpression experiments on the well-characterized, developmentally relevant gene, Ci-Bra, and showed that this technique is applicable for inferring the gene function in C. intestinalis.

  19. Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress.

    PubMed

    Fujikawa, Tetsuya; Munakata, Takeo; Kondo, Shin-ichi; Satoh, Nori; Wada, Shuichi

    2010-03-01

    The genome of Ciona intestinalis contains eight genes for HSP70 superfamily proteins, 36 genes for J-proteins, a gene for a J-like protein, and three genes for BAG family proteins. To understand the stress responses of genes in the HSP70 chaperone system comprehensively, the transcriptional profiles of these 48 genes under heat stress and endoplasmic reticulum (ER) stress were studied using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Heat stress treatment increased the messenger RNA (mRNA) levels of six HSP70 superfamily genes, eight J-protein family genes, and two BAG family genes. In the cytoplasmic group of the DnaK subfamily of the HSP70 family, Ci-HSPA1/6/7-like was the only heat-inducible gene and Ci-HSPA2/8 was the only constitutively active gene which showed striking simplicity in comparison with other animals that have been examined genome-wide so far. Analyses of the time course and temperature dependency of the heat stress responses showed that the induction of Ci-HSPA1/6/7-like expression rises to a peak after heat stress treatment at 28 degrees C (10 degrees C upshift from control temperature) for 1 h. ER stress treatment with Brefeldin A, a drug that is known to act as ER stress inducer, increased the mRNA levels of four HSP70 superfamily genes and four J-protein family genes. Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system.

  20. Gadolinium, a mechano-sensitive channel blocker, inhibits osmosis-initiated motility of sea- and freshwater fish sperm, but does not affect human or ascidian sperm motility.

    PubMed

    Krasznai, Zoltán; Morisawa, Masaaki; Krasznai, Zoárd Tibor; Morisawa, Sachiko; Inaba, Kazuo; Bazsáné, Zsuzsa Kassai; Rubovszky, Bálint; Bodnár, Béla; Borsos, Antal; Márián, Teréz

    2003-08-01

    Exposure to hypo-osmotic or hyperosmotic environment triggers the initiation of fish sperm motility. In this article, we report that calcium and potassium channel blockers do not influence motility of puffer fish sperm but calmodulin antagonists reversibly decrease it, suggesting that calmodulin-Ca(2+) interactions are prerequisite for the initiation of sperm motility in this species. Gadolinium (a stretch activated ion channel blocker) decreased the motility of puffer fish sperm from 92 +/- 3% to 6 +/- 3% and that of carp sperm from 91 +/- 7% to 3.5 +/- 4.3% in a dose-dependent manner (10-40 micro M). The effect of gadolinium was reversible, suggesting that stretch activated ion channels participate in the initiation of sperm motility of the two species. Gadolinium inhibits changes in the isoelectric point of certain proteins of puffer fish sperm, which occur when sperm motility is initiated in a hypertonic solution. Anisotropy measurements showed that hypo-osmotic treatment, which initiates carp sperm motility, increased membrane fluidity. When hypo-osmotic treatment was given in the presence of gadolinium, the sperm membrane remained as rigid as in quiescent cells, while motility was blocked. By contrast, gadolinium did not influence the motility parameters of Ciona or human sperm. Based on these lines of evidence, we suggest that conformational changes of mechanosensitive membrane proteins are involved in osmolality-dependent but not osmolality-independent sperm.

  1. Endozoicomonas Are Specific, Facultative Symbionts of Sea Squirts

    PubMed Central

    Schreiber, Lars; Kjeldsen, Kasper U.; Funch, Peter; Jensen, Jeppe; Obst, Matthias; López-Legentil, Susanna; Schramm, Andreas

    2016-01-01

    Ascidians are marine filter feeders and harbor diverse microbiota that can exhibit a high degree of host-specificity. Pharyngeal samples of Scandinavian and Mediterranean ascidians were screened for consistently associated bacteria by culture-dependent and -independent approaches. Representatives of the Endozoicomonas (Gammaproteobacteria, Hahellaceae) clade were detected in the ascidian species Ascidiella aspersa, Ascidiella scabra, Botryllus schlosseri, Ciona intestinalis, Styela clava, and multiple Ascidia/Ascidiella spp. In total, Endozoicomonas was detected in more than half of all specimens screened, and in 25–100% of the specimens for each species. The retrieved Endozoicomonas 16S rRNA gene sequences formed an ascidian-specific subclade, whose members were detected by fluorescence in situ hybridization (FISH) as extracellular microcolonies in the pharynx. Two strains of the ascidian-specific Endozoicomonas subclade were isolated in pure culture and characterized. Both strains are chemoorganoheterotrophs and grow on mucin (a mucus glycoprotein). The strains tested negative for cytotoxic or antibacterial activity. Based on these observations, we propose ascidian-associated Endozoicomonas to be commensals, living off the mucus continuously secreted into the pharynx. Members of the ascidian-specific Endozoicomonas subclade were also detected in seawater from the Scandinavian sampling site, which suggests acquisition of the symbionts by horizontal transmission. The combined results indicate a host-specific, yet facultative symbiosis between ascidians and Endozoicomonas. PMID:27462299

  2. Ascidia subterranea sp. nov. (Phlebobranchia: Ascidiidae), a new tunicate belonging to the A. sydneiensis Stimpson, 1855 group, found as burrow associate of Axiopsis serratifrons A. Milne-Edwards, 1873 (Decapoda: Axiidae) on Derawan Island, Indonesia.

    PubMed

    Kneer, Dominik; Monniot, Francoise; Stach, Thomas; Christianen, Marjolijn J A

    2013-02-22

    A new tunicate, Ascidia subterranea sp. nov., was found in burrows of the axiid crustacean Axiopsis serratifrons on Derawan Island, Indonesia. It differs from other ascidians in its habitat as well as numerous morphological peculiarities which are described in detail. The shrimp Rostronia stylirostris Holthuis, 1952 was found inside A. subterranea sp. nov., and 4 species of bivalves, 3 species of polychaetes, 1 gastropod, 1 polyplacophoran and 1 sponge species were found as burrow associates besides the ascidian.

  3. Relationships between deep-sea tunicate populations west and east of the Straits of Gibraltar

    NASA Astrophysics Data System (ADS)

    Monniot, Claude; Monniot, Françoise

    Twenty-four species of tunicates were collected from deep bottoms on each side of the Gibraltar sill, in the adjacent Mediterranean Sea and Atlantic Ocean. In the Atlantic, stations bathed by Atlantic and Mediterranean waters were both sampled. No transport of ascidian taxa by the outflow of Mediterranean water into the Atlantic is apparent. The alternative hypothesis of an Atlantic origin of bathyal ascidian species in the Mediterranean Sea is proposed.

  4. Peptidomic analysis of the central nervous system of the protochordate, Ciona intestinalis: homologs and prototypes of vertebrate peptides and novel peptides.

    PubMed

    Kawada, Tsuyoshi; Ogasawara, Michio; Sekiguchi, Toshio; Aoyama, Masato; Hotta, Kohji; Oka, Kotaro; Satake, Honoo

    2011-06-01

    The phylogenetic position of ascidians as the chordate invertebrates closest to vertebrates suggests that they might possess homologs and/or prototypes of vertebrate peptide hormones and neuropeptides as well as ascidian-specific peptides. However, only a small number of peptides have so far been identified in ascidians. In the present study, we have identified various peptides in the ascidian, Ciona intestinalis. Mass spectrometry-based peptidomic analysis detected 33 peptides, including 26 novel peptides, from C. intestinalis. The ascidian peptides are largely classified into three categories: 1) prototypes and homologs of vertebrate peptides, such as galanin/galanin-like peptide, which have never been identified in any invertebrates; 2) peptides partially homologous with vertebrate peptides, including novel neurotesin-like peptides; 3) novel peptides. These results not only provide evidence that C. intestinalis possesses various homologs and prototypes of vertebrate neuropeptides and peptide hormones but also suggest that several of these peptides might have diverged in the ascidian-specific evolutionary lineage. All Ciona peptide genes were expressed in the neural complex, whereas several peptide gene transcripts were also distributed in peripheral tissues, including the ovary. Furthermore, a Ciona neurotensin-like peptide, C. intestinalis neurotensin-like peptide 6, was shown to down-regulate growth of Ciona vitellogenic oocytes. These results suggest that the Ciona peptides act not only as neuropeptides in the neural tissue but also as hormones in nonneuronal tissues and that ascidians, unlike other invertebrates, such as nematodes, insects, and sea urchins, established an evolutionary origin of the peptidergic neuroendocrine, endocrine, and nervous systems of vertebrates with certain specific molecular diversity.

  5. Origin and variation of tunicate secondary metabolites.

    PubMed

    Schmidt, Eric W; Donia, Mohamed S; McIntosh, John A; Fricke, W Florian; Ravel, Jacques

    2012-02-24

    Ascidians (tunicates) are rich sources of structurally elegant, pharmaceutically potent secondary metabolites and, more recently, potential biofuels. It has been demonstrated that some of these compounds are made by symbiotic bacteria and not by the animals themselves, and for a few other compounds evidence exists supporting a symbiotic origin. In didemnid ascidians, compounds are highly variable even in apparently identical animals. Recently, we have explained this variation at the genomic and metagenomic levels and have applied the basic scientific findings to drug discovery and development. This review discusses what is currently known about the origin and variation of symbiotically derived metabolites in ascidians, focusing on the family Didemnidae, where most research has occurred. Applications of our basic studies are also described.

  6. How Fast Is the Sessile Ciona?

    PubMed Central

    Berná, Luisa; Alvarez-Valin, Fernando; D'Onofrio, Giuseppe

    2009-01-01

    Genomewide analyses of distances between orthologous gene pairs from the ascidian species Ciona intestinalis and Ciona savignyi were compared with those of vertebrates. Combining this data with a detailed and careful use of vertebrate fossil records, we estimated the time of divergence between the two ascidians nearly 180 My. This estimation was obtained after correcting for the different substitution rates found comparing several groups of chordates; indeed we determine here that on average Ciona species evolve 50% faster than vertebrates. PMID:20052388

  7. Further EST analysis of endocrine genes that are preferentially expressed in the neural complex of Ciona intestinalis: receptor and enzyme genes associated with endocrine system in the neural complex.

    PubMed

    Sekiguchi, Toshio; Kawashima, Takeshi; Satou, Yutaka; Satoh, Nori

    2007-01-15

    Identification of orthologs of vertebrate neuropeptides and hypothalamic hormones in the neural complex of ascidians suggests integral roles of the ascidian neural complex in the endocrine system. In the present study, we investigated endocrine-related genes expressed in the neural complex of Ciona intestinalis. Comprehensive analyses of 3'-end sequences of the neural complex cDNAs placed 10,029 clones into 4051 independent clusters or genes, 1524 of them being expressed preferentially in this organ. Comparison of the 1524 genes with the human proteome databank demonstrated that 476 matched previously identified human proteins with distinct functions. Further analyses of sequence similarity of the 476 genes demonstrated that 21 genes are candidates for those involved in the endocrine system. Although we cannot detect hormone or peptide candidates, we found 21 genes such as receptors for peptide ligands, receptor-modulating proteins, and processing enzymes. We then characterized the Ciona prohormone convertase 2 (Ci-PC2) and carboxypeptidase E (Ci-CPE), which are associated with endoproteolytic processing of peptide hormone precursors. Furthermore, genes encoding these transcripts are expressed specifically in the neural complex of young adult ascidians. These data provide the molecular basis for further functional studies of the endocrine role of the neural complex of ascidians.

  8. Comparative expression analysis of transcription factor genes in the endostyle of invertebrate chordates.

    PubMed

    Hiruta, Jin; Mazet, Francoise; Yasui, Kinya; Zhang, Peijun; Ogasawara, Michio

    2005-07-01

    The endostyle of invertebrate chordates is a pharyngeal organ that is thought to be homologous with the follicular thyroid of vertebrates. Although thyroid-like features such as iodine-concentrating and peroxidase activities are located in the dorsolateral part of both ascidian and amphioxus endostyles, the structural organization and numbers of functional units are different. To estimate phylogenetic relationships of each functional zone with special reference to the evolution of the thyroid, we have investigated, in ascidian and amphioxus, the expression patterns of thyroid-related transcription factors such as TTF-2/FoxE4 and Pax2/5/8, as well as the forkhead transcription factors FoxQ1 and FoxA. Comparative gene expression analyses depicted an overall similarity between ascidians and amphioxus endostyles, while differences in expression patterns of these genes might be specifically related to the addition or elimination of a pair of glandular zones. Expressions of Ci-FoxE and BbFoxE4 suggest that the ancestral FoxE class might have been recruited for the formation of thyroid-like region in a possible common ancestor of chordates. Furthermore, coexpression of FoxE4, Pax2/5/8, and TPO in the dorsolateral part of both ascidian and amphioxus endostyles suggests that genetic basis of the thyroid function was already in place before the vertebrate lineage.

  9. Ascidiacea (Chordata: Tunicata) of Greece: an updated checklist

    PubMed Central

    Gerovasileiou, Vasilis; Bailly, Nicolas

    2016-01-01

    Abstract Background The checklist of the ascidian fauna (Tunicata: Ascidiacea) of Greece was compiled within the framework of the Greek Taxon Information System (GTIS), an application of the LifeWatchGreece Research Infrastructure (ESFRI) aiming to produce a complete checklist of species recorded from Greece. This checklist was constructed by updating an existing one with the inclusion of recently published records. All the reported species from Greek waters were taxonomically revised and cross-checked with the Ascidiacea World Database. New information The updated checklist of the class Ascidiacea of Greece comprises 75 species, classified in 33 genera, 12 families, and 3 orders. In total, 8 species have been added to the previous species list (4 Aplousobranchia, 2 Phlebobranchia, and 2 Stolidobranchia). Aplousobranchia was the most speciose order, followed by Stolidobranchia. Most species belonged to the families Didemnidae, Polyclinidae, Pyuridae, Ascidiidae, and Styelidae; these 4 families comprise 76% of the Greek ascidian species richness. The present effort revealed the limited taxonomic research effort devoted to the ascidian fauna of Greece, which is attributed to the lack of experts and low sampling effort. Therefore, major knowledge gaps on the ascidian diversity of Greece occur and further research in this field is needed. PMID:27932910

  10. ACAM, a novel member of the neural IgCAM family, mediates anterior neural tube closure in a primitive chordate.

    PubMed

    Morales Diaz, Heidi; Mejares, Emil; Newman-Smith, Erin; Smith, William C

    2016-01-01

    The neural IgCAM family of cell adhesion molecules, which includes NCAM and related molecules, has evolved via gene duplication and alternative splicing to allow for a wide range of isoforms with distinct functions and homophilic binding properties. A search for neural IgCAMs in ascidians (Ciona intestinalis, Ciona savignyi, and Phallusia mammillata) has identified a novel set of truncated family members that, unlike the known members, lack fibronectin III domains and consist of only repeated Ig domains. Within the tunicates this form appears to be unique to the ascidians, and it was designated ACAM, for Ascidian Cell Adhesion Molecule. In C. intestinalis ACAM is expressed in the developing neural plate and neural tube, with strongest expression in the anterior sensory vesicle precursor. Unlike the two other conventional neural IgCAMs in C. intestinalis, which are expressed maternally and throughout the morula and blastula stages, ACAM expression initiates at the gastrula stage. Moreover, C. intestinalis ACAM is a target of the homeodomain transcription factor OTX, which plays an essential role in the development of the anterior central nervous system. Morpholino (MO) knockdown shows that ACAM is required for neural tube closure. In MO-injected embryos neural tube closure was normal caudally, but the anterior neuropore remained open. A similar phenotype was seen with overexpression of a secreted version of ACAM. The presence of ACAM in ascidians highlights the diversity of this gene family in morphogenesis and neurodevelopment.

  11. How the sea squirt nucleus tells mesoderm Not to be endoderm

    PubMed Central

    Parton, Richard M.; Davis, Ilan

    2011-01-01

    Sea squirts are simple invertebrate chordates. In this issue, Takatori et al show nuclear migration within ascidian mesendodermal cells enables polarized localization of Not mRNA, which encodes a homeobox protein that distinguishes mesoderm from endoderm fates. The link between nuclear migration and mRNA localization suggests exciting parallels with protostomes. PMID:20951340

  12. The habitat engineering tunicate Microcosmus sabatieri Roule, 1885 and its associated peracarid epifauna

    NASA Astrophysics Data System (ADS)

    Voultsiadou, Eleni; Pyrounaki, Maria-Myrto; Chintiroglou, Chariton

    2007-08-01

    The solitary ascidian Microcosmus sabatieri is a common ecosystem engineering species on hard bottom sublittoral communities in the Eastern Mediterranean. Peracarida are common inhabitants of biological substrata, such as algae, sponges and ascidians and have been proven to be very sensitive to changes in environmental conditions. The aim of this study was to present and analyse, for the first time, the structure of the peracarid epifaunal assemblage inhabiting this Mediterranean endemic, edible and commercially exploited species. During sampling in the North Aegean Sea, 41 specimens were collected and examined for their peracarid epifauna. Overall, 38 peracarid species were identified, a high number in comparison to those recorded in the few other relevant studies on ascidian epifauna. The great majority of the species were amphipods. By contrast, in terms of abundance, tanaidaceans was the dominant taxon, with Leptochelia savigni being by far the most dominant species. Tube-dwelling suspension-feeders dominated the peracarid epifauna of this tunicate. The suspension feeding mode of epifaunal peracarids is possibly favoured by the high filtration rate of M. sabatieri which is large sized and has an extensive branchial surface. It is suggested that the tube-dwelling habit of tanaidaceans and some amphipods offering extra protection, may further explain their dominance as elements of the epifauna, in contrast to other inquiline peracarids which prefer to search for shelter inside the canals of sponges or, in a few cases inside the mantle cavity of ascidians. Differences in peracarid abundance among the ascidian specimens were attributed to the reproductive and dispersal habits of the former. Species richness, abundance and diversity of the motile peracarid epifauna was dependent on the biomass of the ascidian, but most strongly on the biomass of the sessile epibiontic organisms, such as algae and sponges which, in some cases, had a higher biomass than the ascidian

  13. On some historical and theoretical foundations of the concept of chordates.

    PubMed

    Raineri, Margherita

    2009-03-01

    The concept of chordates arose from the alliance between embryology and evolution in the second half of the nineteenth century, as a result of a theoretical elaboration on Kowalevsky's discoveries about some fundamental similarities between the ontogeny of the lancelet, a putative primitive fish, and that of ascidians, then classified as molluscs. Carrying out his embryological studies in the light of Darwin's theory and von Baer's account of the germ layers, Kowalevsky was influenced by the German tradition of idealistic morphology that was concerned with transformations driven by laws of form, rather than with a gradual evolution occurring by means of variation, selection and adaptation. In agreement with this tradition, Kowalevsky interpreted the vertebrate-like structures of the ascidian larva according to von Kölliker's model of heterogeneous generation. Then, he asserted the homology of the germ layers and their derivatives in different types of animals and suggested a common descent of annelids and vertebrates, in agreement with Saint-Hilaire's hypothesis of the unity of composition of body plans, but in contrast with Haeckel's idea of the Chordonia (chordates). In The Descent of Man Darwin quoted Kowalevsky's discoveries, but accepted Haeckel's interpretation of the ascidian embryology within the frame of a monophyletic tree of life that was produced by the fundamental biogenetic law. Joining embryology to evolution in the light of idealistic morphology, the biogenetic law turned out to be instrumental in bringing forth different evolutionary hypotheses: it was used by Haeckel and Darwin to link vertebrates to invertebrates by means of the concept of chordates, and by Kowalevsky to corroborate the annelid theory of the origin of vertebrates. Yet, there was still another interpretation of Kowalevsky's discoveries. As an adherent to empiricism and to Cuvier's theory of types, von Baer asserted that these discoveries did not prove convincingly a dorsal

  14. Elastic modulus of single cellulose microfibrils from tunicate measured by atomic force microscopy.

    PubMed

    Iwamoto, Shinichiro; Kai, Weihua; Isogai, Akira; Iwata, Tadahisa

    2009-09-14

    The elastic modulus of single microfibrils from tunicate ( Halocynthia papillosa ) cellulose was measured by atomic force microscopy (AFM). Microfibrils with cross-sectional dimensions 8 x 20 nm and several micrometers in length were obtained by oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) as a catalyst and subsequent mechanical disintegration in water and by sulfuric acid hydrolysis. The nanocellulosic materials were deposited on a specially designed silicon wafer with grooves 227 nm in width, and a three-point bending test was applied to determine the elastic modulus using an AFM cantilever. The elastic moduli of single microfibrils prepared by TEMPO-oxidation and acid hydrolysis were 145.2 +/- 31.3 and 150.7 +/- 28.8 GPa, respectively. The result showed that the experimentally determined modulus of the highly crystalline tunicate microfibrils was in agreement with the elastic modulus of native cellulose crystals.

  15. Sialic acids as link to Japanese scientistsDedicated to Prof. Dr. Tamio Yamakawa.

    PubMed Central

    SCHAUER, Roland

    2016-01-01

    This manuscript is dedicated to Prof. Tamio Yamakawa and describes my cooperations on sialic acid-related topics with Japanese scientists during the last 40 years. We studied sialic acids and their O-acetylated derivatives in the sea urchin Pseudocentrotus depressus, in Halocynthia species, and in human and bovine milk. In seafood we mainly searched for N-glycolylneuraminic acid. With synthetic substrates it was shown that sialic acid O-acetylation at C-4 hinders the activity of sialidases, with the exception of viral enzymes. The biosynthesis of Neu5Gc was discussed and the distribution of this sialic acid in dogs followed in modern literature and reviewed regarding their migration. An excellent source of sialic acids is edible bird nest substance (Collocalia mucin) which was used for the synthesis of sialylation inhibitors. PMID:27063181

  16. The Ciona intestinalis cleavage clock is independent of DNA methylation.

    PubMed

    Suzuki, Miho M; Mori, Tomoko; Satoh, Noriyuki

    2016-10-01

    The initiation of embryonic gene expression in ascidian embryos appears to be tightly regulated by the number of DNA replication cycles. DNA methylation is thought to contribute to the clock mechanism that counts the rounds of DNA replication. We used mass spectrometry and whole genome bisulfite sequencing to characterize DNA methylation changes that occur in early developmental stages of the ascidian, Ciona intestinalis. We found that global DNA methylation in early Ciona development was static, and a base-wise comparison between the genomes of consecutive developmental stages found no DNA demethylation that was related to zygotic gene activation. Additionally, 5hmC was hardly detected by mass spectrometry in the developmental samples, suggesting a lack of demethylation mediated by ten eleven translocation (TET) methylcytosine dioxygenase in C. intestinalis. We conclude that DNA methylation is not involved in regulating DNA replication-dependent transcriptional activation.

  17. Long-term coexistence of non-indigenous species in aquaculture facilities.

    PubMed

    Rius, Marc; Heasman, Kevin G; McQuaid, Christopher D

    2011-11-01

    Non-indigenous species (NIS) are a growing problem globally and, in the sea, aquaculture activities are critical vectors for their introduction. Aquaculture introduces NIS, intentionally or unintentionally, and can provide substratum for the establishment of other NIS. Little is known about the co-occurrence of NIS over long periods and we document the coexistence over decades of a farmed NIS (a mussel) with an accidently introduced species (an ascidian). Both are widespread and cause serious fouling problems worldwide. We found partial habitat segregation across depth and the position of rafts within the studied farm, which suggests competitive exclusion of the mussel in dark, sheltered areas and physiological exclusion of the ascidian elsewhere. Both species exhibit massive self-recruitment, with negative effects on the industry, but critically the introduction of NIS through aquaculture facilities also has strong detrimental effects on the natural environment.

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

    PubMed

    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.

  19. Assessment of coastal marine pollution in Galicia (NW Iberian Peninsula); metal concentrations in seawater, sediments and mussels (Mytilus galloprovincialis) versus embryo-larval bioassays using Paracentrotus lividus and Ciona intestinalis.

    PubMed

    Beiras, R; Bellas, J; Fernández, N; Lorenzo, J I; Cobelo-García, A

    2003-10-01

    Sediments from three Galician Rias were tested for toxicity using sea-urchin and ascidian sediment elutriate embryo-larval bioassays. Trace metal contents in seawater, sediments and mussels were also determined and subjected to multidimensional scaling methods which grouped stations according to chemical contamination. High metal contents were found in seawater, sediments and mussels from the Ria of Pontevedra, and moderate levels were detected in the Ria of Vigo and Ria of Arousa. The results revealed that samples assessed as toxic, according to the sea-urchin and ascidian embryo-larval bioassays, were among the most polluted by trace metals. A good agreement was reported between ordination plots resulting from applying multidimensional scaling to the chemical data, and the results of the biological endpoints tested.

  20. Contaminant cocktails: Interactive effects of fertiliser and copper paint on marine invertebrate recruitment and mortality.

    PubMed

    Lawes, Jasmin C; Clark, Graeme F; Johnston, Emma L

    2016-01-15

    Understanding interactive effects of contaminants is critical to predict how human activities change ecosystem structure and function. We examined independent and interactive effects of two contaminants (fertiliser and copper paint) on the recruitment, mortality, and total abundance of developing invertebrate communities in the field, 2, 4, 6, and 8 weeks after substrate submersion. Contaminants affected community structure differently, and produced an intermediate community in combination. Fertiliser increased recruitment and decreased mortality of active filter feeders (ascidians and barnacles), while copper paint decreased recruitment and increased mortality of some taxa. Contaminants applied together affected some taxa (e.g. Didemnid ascidians) antagonistically, as fertiliser mitigated adverse effects of copper paint. Recruitment of active filter feeders appears to be indicative of nutrient enrichment, and their increased abundance may reduce elevated nutrients in modified waterways. This study demonstrates the need to consider both independent and interactive effects of contaminants on marine communities in the field.

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

    PubMed

    Pavão, Mauro S G

    2014-01-01

    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.

  2. Ciona intestinalis as an emerging model organism: its regeneration under controlled conditions and methodology for egg dechorionation.

    PubMed

    Liu, Li-ping; Xiang, Jian-hai; Dong, Bo; Natarajan, Pavanasam; Yu, Kui-jie; Cai, Nan-er

    2006-06-01

    The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide crucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuterostome ancestor and how advanced chordates originated from the simplest chordates. In this paper, a whole-life-span culture of C. intestinalis was conducted. Fed with the diet combination of dry Spirulina, egg yolk, Dicrateria sp., edible yeast and weaning diet for shrimp, C. intestinalis grew up to average 59 mm and matured after 60 d cultivation. This culture process could be repeated using the artificially cultured mature ascidians as material. When the fertilized eggs were maintained under 10, 15, 20, 25 degrees C, they hatched within 30 h, 22 h, 16 h and 12 h 50 min respectively experiencing cleavage, blastulation, gastrulation, neurulation, tailbud stage and tadpole stage. The tadpole larvae were characterized as typical but simplified chordates because of their dorsal nerve cord, notochord and primordial brain. After 8 - 24 h freely swimming, the tadpole larvae settled on the substrates and metamorphosized within 1- 2 d into filter feeding sessile juvenile ascidians. In addition, unfertilized eggs were successfully dechorionated in filtered seawater containing 1% Tripsin, 0.25% EDTA at pH of 10.5 within 40 min. After fertilization, the dechorionated eggs developed well and hatched at normal hatching rate. In conclusion, this paper presented feasible methodology for rearing the tadpole larvae of C. intestinalis into sexual maturity under controlled conditions and detailed observations on the embryogenesis of the laboratory cultured ascidians, which will facilitate developmental and genetic research using this model system.

  3. Genomic Inprinting of the M6P/IGF2 Receptor: A Novel Breast Cancer Susceptibility Mechanism

    DTIC Science & Technology

    2001-07-01

    Nakayama • Yutaka Satou • Nori Satoh Isolation and characterization of genes that are expressed during Ciona intestinalis metamorphosis Received: 6...phosis in Ciona intestinalis . One of the tnes, Ci-metal, that a. initiated at the moment of settlement. According encodes a polypeptide with a putative...very Keywords Ascidians . etamorphosis .Genes. short p riod of time; the tail resorption of Ciona , for Cell signaling • Cell r arrangement example, is

  4. A global assembly line to cyanobactins

    PubMed Central

    Donia, Mohamed S.; Ravel, Jacques; Schmidt, Eric W.

    2009-01-01

    More than 100 cyclic peptides harboring heterocyclized residues are known from marine ascidians, sponges and different genera of cyanobacteria. Here, we report an assembly line responsible for the biosynthesis of these diverse peptides, now called cyanobactins, both in symbiotic and free-living cyanobacteria. By comparing five new cyanobactin biosynthetic clusters, we could produce the prenylated antitumor preclinical candidate, trunkamide, in E. coli culture using genetic engineering. PMID:18425112

  5. Marine Fouling at HMAS STIRLING, Western Australia,

    DTIC Science & Technology

    1984-01-01

    pagenstecheri and several compound ascidians (Fig. 4A). A large influx of other species, primarily the barnacle , Balanus trigonus and tubeworm Filograna...variable numbers throughout the year. Skerman (16] attributed peaks in 0 settlement of the barnacle Elminius modestus to periodic increase in the...settled spat to persist. 4.2 Community Development The fouling community on artificial substrate in Careening Bay progressed through the following

  6. Biological function of unique sulfated glycosaminoglycans in primitive chordates.

    PubMed

    Karamanou, Konstantina; Espinosa, Diana Carolina Restrepo; Fortuna-Costa, Anneliese; Pavão, Mauro Sérgio Gonçalves

    2016-09-10

    Glycosaminoglycans with unique sulfation patterns have been identified in different species of ascidians (sea squirts), a group of marine invertebrates of the Phylum Chordata, sub-phylum Tunicata (or Urochordata). Oversulfated dermatan sulfate composed of [4-α-L-IdoA-(2-O-SO3)(-1) → 3-β-D-GalNAc(4-OSO3)(-1)]n repeating disaccharide units is found in the extracellular matrix of several organs, where it seems to interact with collagen fibers. This dermatan sulfate co-localizes with a decorin-like protein, as indicated by immunohistochemical analysis. Low sulfated heparin/heparan sulfate-like glycans composed mainly of [4-α-L-IdoA-(2-OSO3)(-1) → 4-α-D-GlcN(SO3)(-1) (6-O-SO3)(-1)]n and [4-α-L-IdoA-(2-O-SO3)(-1) → 4-α-D-GlcN(SO3)(-1)]n have also been described in ascidians. These heparin-like glycans occur in intracellular granules of oocyte assessory cells, named test cells, in circulating basophil-like cells in the hemolymph, and at the basement membrane of different ascidian organs. In this review, we present an overview of the structure, distribution, extracellular and intracellular localization of the sulfated glycosaminoglycans in different species and tissues of ascidians. Considering the phylogenetic position of the subphylum Tunicata in the phylum Chordata, a careful analysis of these data can reveal important information about how these glycans evolved from invertebrate to vertebrate animals.

  7. A Guide to the Principal Marine Fouling Organisms, with Particular Reference to Cockburn Sound, W.A.,

    DTIC Science & Technology

    1982-07-01

    Western Australia Molluscs Algae Barnacles Sponges Bryozoa Hydroids Ascidians Tubeworms OSATI GROUPS 0603 ABSTRACT The principal types of marine fouling...Arthropoda, Class Crustacea) 13 7.1 General 13 7.2 Common Species 14 7.3 Other Species 15 7.4 References 15 8. BRYOZOANS (Phylum Bryozoa ) 15 8.1 General 15...Phylum Bryozoa ) 8.1 General Bryozoans grow as sedentary colonies in which a large number of individuals (zooids) are joined in various ways. They

  8. Seasonal variability in the recruitment of macrofouling community in Kudankulam waters, east coast of India

    NASA Astrophysics Data System (ADS)

    Satheesh, S.; Godwin Wesley, S.

    2008-09-01

    The seasonal variability in fouling community recruitment on submerged artificial substratum was studied in Kudankulam coastal water, Gulf of Mannar, East coast of India for a period of two years, from May 2003 to April 2005. The results indicated that the fouling community recruitment occurred throughout the year with varying intensities. Barnacles, ascidians, polychaetes, bivalves and seaweeds were the major fouling groups observed from the test panels. Maximum fouling biomass of 9.17 g dm -2 was observed during August 2004 and a minimum value of 0.233 g dm -2 in February 2004. The biomass build-up on test panels was relatively high during the premonsoon season and low during the postmonsoon months. The number of barnacles settled on the panels varied from 1 to 4460 no. dm -2. The maximum percentage of the ascidian coverage (72%) on test panels was observed during March 2005. In general, July-December was the period of intense recruitment for barnacles and March-May was the period for ascidians.

  9. Gene expression profiles of FABP genes in protochordates, Ciona intestinalis and Branchiostoma belcheri.

    PubMed

    Orito, Wataru; Ohhira, Fuyuko; Ogasawara, Michio

    2015-11-01

    Fatty-acid-binding proteins (FABPs) are small intracellular proteins associated with the transportation of fatty acids. Members of the FABPs share similar amino acid sequences and tertiary structures and form, together with a member of the cellular retinol-binding proteins (CRBPs), the intracellular-lipid-binding protein (iLBP) family. In vertebrates, several types of FABP have been isolated and classified into three subfamilies: 2-4. In invertebrates, several FABP-related proteins have been reported in protostomes and amphioxus; however, little is known about the relationship between their phylogenetic positions and expression patterns. We have performed a genome-wide survey of FABP-related genes in protochordates: amphioxus Branchiostoma belcheri and the ascidian Ciona intestinalis. Comprehensive BLAST searches in NCBI and the Ciona Ghost Database by using amino acid sequences of all FABPs have revealed that the ascidian C. intestinalis and amphioxus B. belcheri contain six and seven FABP-related genes in their haploid genomes, respectively. Expression pattern analyses by whole-mount in situ hybridization in Ciona transparent juveniles and serial-section in situ hybridizations in adult amphioxus have revealed that all genes are mainly expressed in the postpharyngeal digestive tract. In particular, the expression of FABP-related genes of subfamily-2 (liver/ileum type) and subfamily-3 (intestinal type) in the ascidian pyloric gland and amphioxus hepatic cecum provides insight into the evolution of hepatic-related structures of chordates and FABP-related genes.

  10. Recruitment Variability of Coral Reef Sessile Communities of the Far North Great Barrier Reef

    PubMed Central

    Luter, Heidi M.; Duckworth, Alan R.; Wolff, Carsten W.; Evans-Illidge, Elizabeth; Whalan, Steve

    2016-01-01

    One of the key components in assessing marine sessile organism demography is determining recruitment patterns to benthic habitats. An analysis of serially deployed recruitment tiles across depth (6 and 12 m), seasons (summer and winter) and space (meters to kilometres) was used to quantify recruitment assemblage structure (abundance and percent cover) of corals, sponges, ascidians, algae and other sessile organisms from the northern sector of the Great Barrier Reef (GBR). Polychaetes were most abundant on recruitment titles, reaching almost 50% of total recruitment, yet covered <5% of each tile. In contrast, mean abundances of sponges, ascidians, algae, and bryozoans combined was generally less than 20% of total recruitment, with percentage cover ranging between 15–30% per tile. Coral recruitment was very low, with <1 recruit per tile identified. A hierarchal analysis of variation over a range of spatial and temporal scales showed significant spatio-temporal variation in recruitment patterns, but the highest variability occurred at the lowest spatial scale examined (1 m—among tiles). Temporal variability in recruitment of both numbers of taxa and percentage cover was also evident across both summer and winter. Recruitment across depth varied for some taxonomic groups like algae, sponges and ascidians, with greatest differences in summer. This study presents some of the first data on benthic recruitment within the northern GBR and provides a greater understanding of population ecology for coral reefs. PMID:27049650

  11. Revised lineage of larval photoreceptor cells in Ciona reveals archetypal collaboration between neural tube and neural crest in sensory organ formation.

    PubMed

    Oonuma, Kouhei; Tanaka, Moeko; Nishitsuji, Koki; Kato, Yumiko; Shimai, Kotaro; Kusakabe, Takehiro G

    2016-12-01

    The Ciona intestinalis larva has two distinct photoreceptor organs, a conventional pigmented ocellus and a nonpigmented ocellus, that are asymmetrically situated in the brain. The ciliary photoreceptor cells of these ocelli resemble visual cells of the vertebrate retina. Precise elucidation of the lineage of the photoreceptor cells will be key to understanding the developmental mechanisms of these cells as well as the evolutionary relationships between the photoreceptor organs of ascidians and vertebrates. Photoreceptor cells of the pigmented ocellus have been thought to develop from anterior animal (a-lineage) blastomeres, whereas the developmental origin of the nonpigmented ocellus has not been determined. Here, we show that the photoreceptor cells of both ocelli develop from the right anterior vegetal hemisphere: those of the pigmented ocellus from the right A9.14 cell and those of the nonpigmented ocellus from the right A9.16 cell. The pigmented ocellus is formed by a combination of two lineages of cells with distinct embryonic origins: the photoreceptor cells originate from a medial portion of the A-lineage neural plate, while the pigment cell originates from the lateral edge of the a-lineage neural plate. In light of the recently proposed close evolutionary relationship between the ocellus pigment cell of ascidians and the cephalic neural crest of vertebrates, the ascidian ocellus may represent a prototypic contribution of the neural crest to a cranial sensory organ.

  12. Territoriality and Conflict Avoidance Explain Asociality (Solitariness) of the Endosymbiotic Pea Crab Tunicotheres moseri

    PubMed Central

    Ambrosio, Louis J.; Baeza, J. Antonio

    2016-01-01

    Host monopolization theory predicts symbiotic organisms inhabiting morphologically simple, relatively small and scarce hosts to live solitarily as a result of territorial behaviors. We tested this prediction with Tunicotheres moseri, an endosymbiotic crab dwelling in the atrial chamber of the morphologically simple, small, and relatively scarce ascidian Styela plicata. As predicted, natural populations of T. moseri inhabit ascidian hosts solitarily with greater frequency than expected by chance alone. Furthermore, laboratory experiments demonstrated that intruder crabs take significantly longer to colonize previously infected compared to uninfected hosts, indicating as expected, that resident crabs exhibit monopolization behaviors. While territoriality does occur, agonistic behaviors employed by T. moseri do not mirror the overt behaviors commonly reported for other territorial crustaceans. Documented double and triple cohabitations in the field coupled with laboratory observations demonstrating the almost invariable success of intruder crabs colonizing occupied hosts, suggest that territoriality is ineffective in completely explaining the solitary social habit of this species. Additional experiments showed that T. moseri juveniles and adults, when searching for ascidians use chemical cues to avoid hosts occupied by conspecifics. This conspecific avoidance behavior reported herein is a novel strategy most likely employed to preemptively resolve costly territorial conflicts. In general, this study supports predictions central to host monopolization theory, but also implies that alternative behavioral strategies (i.e., conflict avoidance) may be more important than originally thought in explaining the host use pattern of symbiotic organisms. PMID:26910474

  13. AMPA glutamate receptors are required for sensory-organ formation and morphogenesis in the basal chordate.

    PubMed

    Hirai, Shinobu; Hotta, Kohji; Kubo, Yoshihiro; Nishino, Atsuo; Okabe, Shigeo; Okamura, Yasushi; Okado, Haruo

    2017-04-11

    AMPA-type glutamate receptors (GluAs) mediate fast excitatory transmission in the vertebrate central nervous system (CNS), and their function has been extensively studied in the mature mammalian brain. However, GluA expression begins very early in developing embryos, suggesting that they may also have unidentified developmental roles. Here, we identify developmental roles for GluAs in the ascidian Ciona intestinalis Mammals express Ca(2+)-permeable GluAs (Ca-P GluAs) and Ca(2+)-impermeable GluAs (Ca-I GluAs) by combining subunits derived from four genes. In contrast, ascidians have a single gluA gene. Taking advantage of the simple genomic GluA organization in ascidians, we knocked down (KD) GluAs in Ciona and observed severe impairments in formation of the ocellus, a photoreceptive organ used during the swimming stage, and in resorption of the tail and body axis rotation during metamorphosis to the adult stage. These defects could be rescued by injection of KD-resistant GluAs. GluA KD phenotypes could also be reproduced by expressing a GluA mutant that dominantly inhibits glutamate-evoked currents. These results suggest that, in addition to their role in synaptic communication in mature animals, GluAs also have critical developmental functions.

  14. Self/non-self recognition mechanisms in sexual reproduction: new insight into the self-incompatibility system shared by flowering plants and hermaphroditic animals.

    PubMed

    Sawada, Hitoshi; Morita, Masaya; Iwano, Megumi

    2014-08-01

    Sexual reproduction is an essential process for generating a genetic variety in the next generation. However, most flowering plants and hermaphroditic animals potentially allow self-fertilization. Approximately 60% of angiosperms possess a self-incompatibility (SI) system to avoid inbreeding. The SI system functions at a process of interaction between pollen (or pollen tube) and the pistil. These SI-responsible factors (S-determinants) in pollen and the pistil are encoded by highly polymorphic multiallelic genes in the S-locus, which are tightly linked making a single haplotype. Different taxonomic families utilize different types of S-determinant proteins. In contrast to the plant system, the mechanisms of SI in simultaneously hermaphroditic animals are largely unknown. Among them, promising candidates for SI in ascidians (primitive chordates) were recently identified. The SI system in the ascidian Cionaintestinalis was found to be very similar to those in flowering plants: The products of sperm- and egg-side multiallelic SI genes, which are tight linked and highly polymorphic, appear to be responsible for the SI system as revealed by genetic analysis. These findings led us to speculate that the SI systems in plants and animals evolved in a manner of convergent evolution. Here, we review the current understanding of the molecular mechanisms of the SI system in flowering plants, particularly Brassicacea, and in ascidians from the viewpoint of common mechanisms shared by plants and animals.

  15. Evolution and the origin of the visual retinoid cycle in vertebrates.

    PubMed

    Kusakabe, Takehiro G; Takimoto, Noriko; Jin, Minghao; Tsuda, Motoyuki

    2009-10-12

    Absorption of a photon by visual pigments induces isomerization of 11-cis-retinaldehyde (RAL) chromophore to all-trans-RAL. Since the opsins lacking 11-cis-RAL lose light sensitivity, sustained vision requires continuous regeneration of 11-cis-RAL via the process called 'visual cycle'. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual retinoid cycles between different photoreceptors of vertebrates, including rods, cones and non-visual photoreceptors, as well as between vertebrates and invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase. The entire process of the visual cycle can occur inside the photoreceptor cells with distinct subcellular compartmentalization, although the visual cycle components are also present in surrounding non-photoreceptor cells. The adult ascidian probably uses RPE65 isomerase, and trans-to-cis isomerization may occur in distinct cellular compartments, which is similar to the vertebrate situation. The complete transition to the sophisticated retinoid cycle of vertebrates may have required acquisition of new genes, such as interphotoreceptor retinoid-binding protein, and functional evolution of the visual cycle genes.

  16. Ependymal cells of chordate larvae are stem-like cells that form the adult nervous system.

    PubMed

    Horie, Takeo; Shinki, Ryoko; Ogura, Yosuke; Kusakabe, Takehiro G; Satoh, Nori; Sasakura, Yasunori

    2011-01-27

    In ascidian tunicates, the metamorphic transition from larva to adult is accompanied by dynamic changes in the body plan. For instance, the central nervous system (CNS) is subjected to extensive rearrangement because its regulating larval organs are lost and new adult organs are created. To understand how the adult CNS is reconstructed, we traced the fate of larval CNS cells during ascidian metamorphosis by using transgenic animals and imaging technologies with photoconvertible fluorescent proteins. Here we show that most parts of the ascidian larval CNS, except for the tail nerve cord, are maintained during metamorphosis and recruited to form the adult CNS. We also show that most of the larval neurons disappear and only a subset of cholinergic motor neurons and glutamatergic neurons are retained. Finally, we demonstrate that ependymal cells of the larval CNS contribute to the construction of the adult CNS and that some differentiate into neurons in the adult CNS. An unexpected role of ependymal cells highlighted by this study is that they serve as neural stem-like cells to reconstruct the adult nervous network during chordate metamorphosis. Consequently, the plasticity of non-neuronal ependymal cells and neuronal cells in chordates should be re-examined by future studies.

  17. Recruitment Variability of Coral Reef Sessile Communities of the Far North Great Barrier Reef.

    PubMed

    Luter, Heidi M; Duckworth, Alan R; Wolff, Carsten W; Evans-Illidge, Elizabeth; Whalan, Steve

    2016-01-01

    One of the key components in assessing marine sessile organism demography is determining recruitment patterns to benthic habitats. An analysis of serially deployed recruitment tiles across depth (6 and 12 m), seasons (summer and winter) and space (meters to kilometres) was used to quantify recruitment assemblage structure (abundance and percent cover) of corals, sponges, ascidians, algae and other sessile organisms from the northern sector of the Great Barrier Reef (GBR). Polychaetes were most abundant on recruitment titles, reaching almost 50% of total recruitment, yet covered <5% of each tile. In contrast, mean abundances of sponges, ascidians, algae, and bryozoans combined was generally less than 20% of total recruitment, with percentage cover ranging between 15-30% per tile. Coral recruitment was very low, with <1 recruit per tile identified. A hierarchal analysis of variation over a range of spatial and temporal scales showed significant spatio-temporal variation in recruitment patterns, but the highest variability occurred at the lowest spatial scale examined (1 m-among tiles). Temporal variability in recruitment of both numbers of taxa and percentage cover was also evident across both summer and winter. Recruitment across depth varied for some taxonomic groups like algae, sponges and ascidians, with greatest differences in summer. This study presents some of the first data on benthic recruitment within the northern GBR and provides a greater understanding of population ecology for coral reefs.

  18. Molecular phylogeny and biogeography of an ancient Holarctic lineage of mygalomorph spiders (Araneae: Antrodiaetidae: Antrodiaetus).

    PubMed

    Hendrixson, Brent E; Bond, Jason E

    2007-03-01

    The mygalomorph spider genera Antrodiaetus and Atypoides (Antrodiaetidae) belong to an ancient lineage that has persisted since at least the Cretaceous. These spiders display a classic disjunct Holarctic distribution with species in the eastern Palaearctic plus the western and eastern Nearctic. Prior phylogenetic analyses of this group have been proposed on the basis of morphology, but lack strong support and independent corroboration. Here we present the first phylogenetic analysis of species-level relationships based on molecular data obtained from the mitochondrial (cytochrome c oxidase subunit I) and nuclear (18S and 28S rRNA) genomes. Analyses corroborate earlier findings that Atypoides forms a paraphyletic grade with respect to Antrodiaetus, and consequently, that genus is formally synonymized under Antrodiaetus. In addition, our results support the relatively early divergence of Antrodiaetus roretzi. Antrodiaetus pacificus is "paraphyletic" with respect to the A. lincolnianus group and is likely an assemblage of numerous species. The final topology based on a combined molecular dataset, in conjunction with two different molecular dating techniques (penalized likelihood plus a Bayesian approach) and ancestral distribution reconstructions, was used to infer the historical biogeography of these spiders. Trans-Beringian and trans-Atlantic routes appear to account for the present-day distribution of Antrodiaetus in Japan and North America. Future studies on Antrodiaetus phylogeny will be used to address questions regarding morphological stasis and the evolution of quantitative morphological characters.

  19. [Evolutional principles of homology in regulatory genes of myogenesis].

    PubMed

    Ozerniuk, I D; Miuge, N S

    2012-01-01

    Analysis of early steps in muscular system development of invertebrates and vertebrates shows that early steps of myogenesis are regulated by genes-orthologs mainly belonging to two families, Pax and bHLH. In the majority of the following organisms, muscles formation (steps of determination and the earliest steps of myogenesis) is regulated by genes orthologs Pax3 which belong to the family Pax: nematodes (Caenorhabditis elegans, Pristionchus pacificus), insects (Drosophila melanogaster), echinoderms (Strongylocentrotus purpuratus), sea squirts (Ciona intestinalis, Holocynthia roretzi), fishes (Danio rerio), amphibians (Xenopus laevis), birds, and mammals (mouse, rat). The nematode C. elegans is an exception since formation of its muscles in this period is regulated by homeobox gene Pal-1 belonging to the family Caudal. The sea squirt C. intestinalis is also an exception because the earliest steps of development involved in further muscle formation are accompanied by activation of the gene CiSna (snail) (gene family basic Zinc finger). The next steps of myogenesis in all analyzed species are regulated by genes orthologs belonging to the family of transcriptional factors bHLH. They along with genes Pax3 are characterized by a high extent of homology in all studied groups of animals.

  20. High quality draft genome sequence of the slightly halophilic bacterium Halomonas zhanjiangensis type strain JSM 078169T (DSM 21076T) from a sea urchin in southern China

    PubMed Central

    Zhou, Yu; Li, Rui; Gao, Xiao-Yang; Lapidus, Alla; Han, James; Haynes, Matthew; Lobos, Elizabeth; Huntemann, Marcel; Pati, Amrita; Ivanova, Natalia N.; Rohde, Manfred; Mavromatis, Konstantinos; Tindall, Brian J.; Markowitz, Victor; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos C.; Li, Wen-Jun

    2014-01-01

    Halomonas zhanjiangensis Chen et al. 2009 is a member of the genus Halomonas, family Halomonadaceae, class Gammaproteobacteria. Representatives of the genus Halomonas are a group of halophilic bacteria often isolated from salty environments. The type strain H. zhanjiangensis JSM 078169T was isolated from a sea urchin (Hemicentrotus pulcherrimus) collected from the South China Sea. The genome of strain JSM 078169T is the fourteenth sequenced genome in the genus Halomonas and the fifteenth in the family Halomonadaceae. The other thirteen genomes from the genus Halomonas are H. halocynthiae, H. venusta, H. alkaliphila, H. lutea, H. anticariensis, H. jeotgali, H. titanicae, H. desiderata, H. smyrnensis, H. salifodinae, H. boliviensis, H. elongata and H stevensii. Here, we describe the features of strain JSM 078169T, together with the complete genome sequence and annotation from a culture of DSM 21076T. The 4,060,520 bp long draft genome consists of 17 scaffolds with the 3,659 protein-coding and 80 RNA genes and is a part of Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes (KMG) project. PMID:25197480

  1. High quality draft genome sequence of the slightly halophilic bacterium Halomonas zhanjiangensis type strain JSM 078169(T) (DSM 21076(T)) from a sea urchin in southern China.

    PubMed

    Zhou, Yu; Li, Rui; Gao, Xiao-Yang; Lapidus, Alla; Han, James; Haynes, Matthew; Lobos, Elizabeth; Huntemann, Marcel; Pati, Amrita; Ivanova, Natalia N; Rohde, Manfred; Mavromatis, Konstantinos; Tindall, Brian J; Markowitz, Victor; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos C; Li, Wen-Jun

    2014-06-15

    Halomonas zhanjiangensis Chen et al. 2009 is a member of the genus Halomonas, family Halomonadaceae, class Gammaproteobacteria. Representatives of the genus Halomonas are a group of halophilic bacteria often isolated from salty environments. The type strain H. zhanjiangensis JSM 078169(T) was isolated from a sea urchin (Hemicentrotus pulcherrimus) collected from the South China Sea. The genome of strain JSM 078169(T) is the fourteenth sequenced genome in the genus Halomonas and the fifteenth in the family Halomonadaceae. The other thirteen genomes from the genus Halomonas are H. halocynthiae, H. venusta, H. alkaliphila, H. lutea, H. anticariensis, H. jeotgali, H. titanicae, H. desiderata, H. smyrnensis, H. salifodinae, H. boliviensis, H. elongata and H stevensii. Here, we describe the features of strain JSM 078169(T), together with the complete genome sequence and annotation from a culture of DSM 21076(T). The 4,060,520 bp long draft genome consists of 17 scaffolds with the 3,659 protein-coding and 80 RNA genes and is a part of Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes (KMG) project.

  2. Cellulose hydrolysis ability of a Clostridium thermocellum cellulosome containing small-size scaffolding protein CipA.

    PubMed

    Deng, Lan; Mori, Yutaka; Sermsathanaswadi, Junjarus; Apiwatanapiwat, Waraporn; Kosugi, Akihiko

    2015-10-20

    Mutant Clostridium thermocellum YM72 that produces small-size scaffolding protein CipA (ssCipA) was isolated from wild-type YM4. Sequencing of ssCipA revealed that two domains, cohesin 6 and cohesin 7, were not present. Cellulosome prepared from YM72 exhibited a significant reduction of hydrolysis ability on crystalline celluloses such as Sigmacell type-20 and cellulose from Halocynthia. To investigate this influence in vitro, artificial cellulosomes were assembled as recombinant CipA (rCipA) and ssCipA (rssCipA) using native free-cellulosomal subunits. The cellulosome assembled using rssCipA showed a 1.8-fold decrease in the hydrolysis of crystalline cellulose compared with that of rCipA. However, no significant differences in the hydrolysis of carboxymethylcellulose and acid-swollen cellulose were observed. One protein band was missing from the complex that was assembled using rssCipA (confirmed by native-PAGE). The missing protein was identified as CelJ, which is a major cellulosomal subunit. This suggests that insufficient cooperation of CelJ into the cellulosome results in the significant reduction of hydrolysis toward crystalline cellulose. These results indicate that cohesin 6 and 7 may be responsible for the cooperation of CelJ through cohesin and dockerin interactions, and adequate cooperation of CelJ into the cellulosome is important for significant hydrolysis of crystalline cellulose.

  3. Embryology of a planktonic tunicate reveals traces of sessility.

    PubMed

    Stach, Thomas; Winter, Jonas; Bouquet, Jean-Marie; Chourrout, Daniel; Schnabel, Ralf

    2008-05-20

    A key problem in understanding deuterostome evolution has been the origin of the chordate body plan. A biphasic life cycle with a sessile adult and a free-swimming larva is traditionally considered ancestral in chordates with subsequent neotenic loss of the sessile adult stage. Molecular phylogenies challenged this view, suggesting that the primitive life cycle in chordates was entirely free-living as in modern day larvaceans. Here, we report the precise cell lineage and fate map in the normal embryo of the larvacean Oikopleura dioica, using 4D microscopy technique and transmission electron microscopy. We document the extraordinary rapidity of cleavage and morphogenetic events until hatching and demonstrate that--compared with ascidians--fate restriction occurs considerably earlier in O. dioica and that clonal organization of the cell lineage is more tightly coupled to tissue fate. We show that epidermal cells in the trunk migrate through 90 degrees, reminiscent of events in ascidian metamorphosis and that the axis of bilateral symmetry in the tail rotates in relation to the trunk. We argue that part of the tail muscle cells are ectomesodermal, because they are more closely associated with prospective epidermis than with other tissues in the cell lineage. Cladistic comparison with other deuterostomes suggests that these traits are derived within tunicates strengthening the hypothesis that the last common ancestor of tunicates had a sessile adult and thus support traditional morphology-derived scenarios. Our results allow hypothesizing that molecular developmental mechanisms known from ascidian models are restricted to fewer, yet identifiable, cells in O. dioica.

  4. A standardisation of Ciona intestinalis (Chordata, Ascidiacea) embryo-larval bioassay for ecotoxicological studies.

    PubMed

    Bellas, Juan; Beiras, Ricardo; Vázquez, Elsa

    2003-11-01

    A standardisation of the ascidian Ciona intestinalis embryo-larval bioassay for marine pollution assessment has been developed. The minimum percentage of embryogenesis success was established to assess the quality of the biological material used; minimum sample size and number of replicates per treatment were also estimated. The suitability of artificial and natural seawater for the incubation of ascidian embryos and larvae was compared, and the optimum conditions of temperature, salinity, pH, density of embryos in the vials and the sperm/egg ratio were investigated. On the basis of the 10th percentile of the distribution of larval abnormalities, we proposed a threshold of 50% normal larvae in the control in order to consider the test of acceptable biological quality. According to our results n=5 is a sufficiently high replication to detect 5% differences among treatment means with a power of P=90% and alpha=0.05, and a sampling size >/=222 allows a 95% confidence in the estimate with an error of 0.05. Egg density did not affect larval development within the range 1-20 eggs/ml, and the optimum sperm/egg ratio which fertilise 100% of the eggs was 3000-30,000 sperm/egg (i.e. 10(8)-10(7) sperm/ml). There were not significant differences between the two water types tested, and the optimum tolerance ranges were 18-23 degrees C temperature, 34-42 ppt salinity (42 ppt was the highest salinity tested), and 7.4-8.8 pH. The median effective concentration (EC(50)) of copper (Cu) causing a 50% reduction of normal hatched larvae was 54.2 microg/l (0.85 microM), which shows a sensitivity of this species similar to the commonly used bivalve and sea-urchin tests. The ascidian embryo-larval bioassay is an accurate, reliable, simple and rapid method that can be used in ecotoxicological studies.

  5. Laboratory assessment of the antifouling potential of a soluble-matrix paint laced with the natural compound polygodial.

    PubMed

    Cahill, Patrick Louis; Heasman, Kevin; Jeffs, Andrew; Kuhajek, Jeanne

    2013-09-01

    Polygodial is a potent and selective inhibitor of ascidian metamorphosis that shows promise for controlling fouling by ascidians in bivalve aquaculture. The current study examined the potency of, and associated effects of seawater exposure on, a rosin-based soluble-matrix paint laced with 0.08-160 ng polygodial g(-1) wet paint matrix. Paint-coated surfaces were soaked in seawater for 0, 2, 4 or 12 weeks prior to screening for antifouling activity using a bioassay based on the nuisance ascidian Ciona savignyi Herdman. Mortality was greater (mean 50% lethal concentration: 5 ± 2 ng g(-1); mean 75% lethal concentration: 17 ± 4 ng g(-1)) and metamorphosis was inhibited (mean 50% anti-metamorphic concentration: 2 ± 0.4 ng g(-1); mean 75% anti-metamorphic concentration: 15 ± 10 ng g(-1)) in C. savignyi larvae exposed to polygodial-laced soluble-matrix paints, relative to control paints without polygodial. Soaking in seawater prior to testing reduced the efficacy of the formulation up to nearly 12-fold, but even after soaking for 12 weeks paints laced with polygodial at 160 ng g(-1) wet paint matrix prevented ⩾90% of the larvae of C. savignyi from completing metamorphosis. The outcome of this experiment provides a positive first step in evaluating the suitability of polygodial-laced soluble-matrix paints for use in aquaculture.

  6. Haplostoma dudleyae sp. nov. (Cyclopoida: Ascidicolidae), parasitic in Eudistoma olivaceum from the Indian River in southern Florida

    NASA Astrophysics Data System (ADS)

    Ooishi, S.

    1998-06-01

    Haplostoma dudleyae sp. nov. is described and illustrated on the basis of females found in a compound ascidian ( Eudistoma olivaceum) collected from the Indian River in southern Florida, USA. Each parasitized zooid has a single female copepod. The egg sacs of the female are paired and, when laid, are almost U-shaped and folded against the dorsal side of the body. Haplostoma dudleyae and two other species ( H. canui Chatton and Harant, 1924, and H. humesi Ooishi, 1995) constitute a subgroup within the genus Haplostoma.

  7. Isolation of polymorphic microsatellite loci for the marine invader Microcosmus squamiger (Ascidiacea).

    PubMed

    Rius, Marc; Turon, Xavier; Pascual, Marta

    2008-11-01

    The ascidian Microcosmus squamiger is native to Australia and has recently spread worldwide. It has become a pest in some littoral communities within its introduced range. An enriched genomic library of M. squamiger resulted in a total of eight polymorphic loci that were genotyped in 20 individuals from a population within its introduced range, and 20 individuals more from a native population. The mean number of alleles per locus was 5.33 and mean observed heterozygosity was 0.432. No significant linkage disequilibrium was found among loci pairs. Significant genetic differentiation was observed between populations.

  8. Genetic Regulatory Networks in Embryogenesis and Evolution

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The article introduces a series of papers that were originally presented at a workshop titled Genetic Regulatory Network in Embryogenesis and Evaluation. Contents include the following: evolution of cleavage programs in relationship to axial specification and body plan evolution, changes in cell lineage specification elucidate evolutionary relations in spiralia, axial patterning in the leech: developmental mechanisms and evolutionary implications, hox genes in arthropod development and evolution, heterochronic genes in development and evolution, a common theme for LIM homeobox gene function across phylogeny, and mechanisms of specification in ascidian embryos.

  9. Recent Advances in Drug Discovery from South African Marine Invertebrates.

    PubMed

    Davies-Coleman, Michael T; Veale, Clinton G L

    2015-10-14

    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.

  10. Recent Advances on the Total Syntheses of Communesin Alkaloids and Perophoramidine.

    PubMed

    Trost, Barry M; Osipov, Maksim

    2015-11-09

    The communesin alkaloids are a diverse family of Penicillium-derived alkaloids. Their caged-polycyclic structure and intriguing biological profiles have made these natural products attractive targets for total synthesis. Similarly, the ascidian-derived alkaloid, perophoramidine, is structurally related to the communesins and has also become a popular target for total synthesis. This review serves to summarize the many elegant approaches that have been developed to access the communesin alkaloids and perophoramidine. Likewise, strategies to access the communesin ring system are reviewed.

  11. Intracellular coagulation inhibits the extraction of proteins from Prochloron

    NASA Technical Reports Server (NTRS)

    Fall, R.; Lewin, R. A.; Fall, L. R.

    1983-01-01

    Protein extraction from the prokaryotic alga Prochloron LP (isolated from the ascidian host Lissoclinum patella) was complicated by an irreversible loss of cell fragility in the isolated algae. Accompanying this phenomenon, which is termed intracellular coagulation, was a redistribution of thylakoids around the cell periphery, a loss of photosynthetic O2 production, and a drastic decrease in the extractability of cell proteins. Procedures are described for the successful preparation and transport of cell extracts yielding the enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase as well as other soluble proteins.

  12. Fertilization and normal development in Ascidiella aspersa (Tunicata) studied with Nomarski-optics

    NASA Astrophysics Data System (ADS)

    Niermann-Kerkenberg, Eva; Hofmann, Dietrich Kurt

    1989-06-01

    Normal development of Ascidiella aspersa was studied over a period of approx. 24 h at 20°C from egg insemination through metamorphosis of the tadpole larva using Nomarski-optics. Records were made of spermatozoa attaching to and passing through the cellular envelopes and the chorion of the egg. Egg shape alterations upon entry of the fertilizing sperm, which reflect the early phase of ooplasmic segregation, were monitored in intact and dechorionated eggs. The time course of normal development was recorded, and prominent stages were photographed within or deprived of the egg envelopes. The present observations are compared with recent accounts on early development in other solitary ascidian species.

  13. Recent Advances in Drug Discovery from South African Marine Invertebrates

    PubMed Central

    Davies-Coleman, Michael T.; Veale, Clinton G. L.

    2015-01-01

    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. PMID:26473891

  14. A new species of the genus Rhopalaea (Class: Ascidiacea) from the Red Sea.

    PubMed

    Shenkar, Noa

    2013-01-03

    During regular surveys and collection of ascidians along the Red Sea coast of Israel, several specimens of an undescribed species of Rhopalaea were collected. Samples were collected by SCUBA from the natural coral reef and man-made structures at depths between 10 to 40m. This is the first species of the genus Rhopalaea described from the Red Sea, which is characterized by a transparent, uncolored gelatinous tunic with elongated attachment extensions, and is distinguished by its eight atrial lobes, thoracic muscle arrangement, and branchial sac structure.

  15. Solwaric acids A and B, antibacterial aromatic acids from a marine Solwaraspora sp.

    PubMed

    Ellis, Gregory A; Wyche, Thomas P; Fry, Charles G; Braun, Doug R; Bugni, Tim S

    2014-02-14

    Two novel trialkyl-substituted aromatic acids, solwaric acids A and B, were isolated from a marine Solwaraspora sp. cultivated from the ascidian Trididemnum orbiculatum. Solwaric acids A and B were isotopically labeled with U-¹³C glucose, and analysis of a ¹³C-¹³C COSY allowed for unambiguous determination of the location of the phenyl methyl group. The two novel compounds demonstrated antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA).

  16. Influence of submersion season on the development of test panel biofouling communities in a tropical coast

    NASA Astrophysics Data System (ADS)

    Satheesh, S.; Wesley, S. G.

    2011-08-01

    The effect of test panel submersion season on the colonization of biofouling communities in a tropical coast revealed that the effects of panel submersion time should be taken into consideration for modelling fouling community recruitment dynamics in coastal systems or during the field trials of antifouling coatings. Wooden test panels fitted onto a raft were submerged during pre-monsoon, monsoon and post-monsoon seasons for the development of the biofouling community. Results showed considerable variation in the colonization of fouling communities on test panels submerged during different seasons. Barnacles, tubeworms, ascidians and seaweeds were the major fouling communities that colonized the test panels. The total biomass of the fouling communities that settled on the post-monsoon season panels varied from the initial value of 2.72 g dm -2 to a maximum of 44.5 g dm -2. On the panels submerged during monsoon season, the total biomass of fouling communities varied between 0.78 g dm -2 and 69.9 g dm -2. The total fouling biomass on the pre-monsoon season panels varied between 2.95 and 33.5 g dm -2. Barnacles were the initial colonizers on the panels submerged during pre-monsoon and post-monsoon seasons. Soft-bodied organisms such as ascidians dominated the monsoon season-initiated panel series during the initial period.

  17. Seasonal, annual, and spatial variation in the development of hard bottom communities

    NASA Astrophysics Data System (ADS)

    Harms, J.; Anger, K.

    1983-06-01

    The development of hard bottom communities has been studied on test panels in Helgoland Harbour (German Bight) since 1977. Settlement and growth of epibenthic species was examined monthly. Natural variation in different seasons, years, and at three stations (the latter, only in 1981 and 1982) was investigated. At Station A (Binnenhafen), barnacles (Balanus crenatus) and polychaetes (Polydora ciliata) were always among the first settlers in spring. They were followed by other barnacles (Elminius modestus, Balanus improvisus) and by colonial ascidians (Botryllus schlosseri). The latter species often dominated from August to October, and tended to overgrow the barnacle populations. E. modestus showed strong annual variation, probably due to extremely low winter temperatures: after the cold winter of 1978/79, its populations were less dense than in previous years. In 1981 they recovered, and settlement increased again, but the cold winter 1981/82 damaged the population again. At Station B (Nordosthafen), mussels (Mytilus edulis) soon covered barnacles and empty space. By October they had monopolized the fouling community. At Station C (Südhafen), barnacle settlement in spring was followed by an overgrowth of hydrozoans ( Laomedea spec.). In summer, ascidians ( Ciona intestinalis and Ascidiella aspersa) settled and began to dominate. Barnacles were weaker in the competition for space as opposed to later colonizers at all three stations.

  18. Expression of a single prominin homolog in the embryo of the model chordate Ciona intestinalis.

    PubMed

    Russo, Monia T; Racioppi, Claudia; Zanetti, Laura; Ristoratore, Filomena

    2014-05-01

    Prominins are a family of pentaspan transmembrane glycoproteins, expressed in various types of cells, including stem and cancer stem cells in mammals. Prominin-1 is critical in generating and maintaining the structure of the photoreceptors in the eye since mutations in the PROM1 gene are associated with retinal and macular degeneration in human. In this study, we identified a single prominin homolog, Ci-prom1/2, in the model chordate the ascidian Ciona intestinalis and characterized Ci-prom1/2 expression profile in relation to photoreceptor differentiation during Ciona embryonic development. In situ hybridization experiments show Ci-prom1/2 transcripts localized in the developing central nervous system, predominantly in photoreceptor cell precursors as early as neurula stage and expression is maintained through larva stage in photoreceptor cells around the simple eye. We also isolated the regulatory region responsible for the specific spatio-temporal expression of the Ci-prom1/2 in photoreceptor cell lineage. Collectively, we report that Ci-prom1/2 is a novel molecular marker for ascidian photoreceptor cells and might represent a potential source to enlarge the knowledge about the function of prominin family in photoreceptor cell evolution and development.

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

    PubMed

    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.

  20. Chondroitin 4-O-sulfotransferases are required for cell adhesion and morphogenesis in the Ciona intestinalis embryo.

    PubMed

    Nakamura, Jun; Tetsukawa, Akira; Fujiwara, Shigeki

    2015-01-01

    Chondroitin sulfate (CS) is a carbohydrate component of proteoglycans. Several types of sulfotransferases determine the pattern of CS sulfation, and thus regulate the biological functions of proteoglycans. The protochordate ascidians are the closest relatives of vertebrates, but the functions of their sulfotransferases have not been investigated. Here, we show that two chondroitin 4-O-sulfotransferases (C4STs) play important roles in the embryonic morphogenesis of the ascidian Ciona intestinalis. Ci-C4ST-like1 is predominantly expressed in the epidermis and muscle. Epidermal and muscle cells became spherical upon the injection of a Ci-C4ST-like1-specific morpholino oligo (MO), thus suggesting weakened cell adhesion. Co-injection of a Ci-C4ST-like1-expressing transgene rescued the phenotype, suggesting that the effects of the MO were specific. Ci-C4ST-like3 was expressed in the central nervous system, muscle, and mesenchyme. A specific MO appeared to affect cell adhesion in the epidermis and muscle. Convergent extension movement of notochordal cells was also impaired. Forced expression of Ci-C4ST-like3 restored normal morphogenesis, suggesting that the effects of the MO were specific. The present study suggests that Ci-C4ST-like1 and Ci-C4ST-like3 are required for cell adhesion mainly in the epidermis and muscle.

  1. Tunic phagocytes are involved in allorejection reaction in the colonial tunicate Aplidium yamazii (Polyclinidae, Ascidiacea).

    PubMed

    Ishii, Teruhisa; Hirose, Euichi; Taneda, Yasuho

    2008-04-01

    The colonial ascidian Aplidium yamazii exhibited an allorejection reaction when two allogeneic colonies were brought into contact at their growing edges or at artificial cut surfaces. This species has no vascular network in the tunic, unlike the botryllid ascidians, which have a vascular network throughout the colony's common tunic. In the allorejection reaction induced by contact at the growing edges, some small, hard-packed tunic masses were formed at the contact points. Histological and electron microscopic investigation of these tunic masses revealed that they contained aggregates of tunic cells, with tunic phagocytes being the major cell type present. Some of the tunic phagocytes in these tunic masses appeared to be disintegrating. When allogeneic colonies were placed in contact at their artificial cut surfaces, the colonies partially fused, then separated. In this allorejection reaction, some loosely packed tunic masses remained in the gap between the two withdrawn colonies. These results strongly suggest that the tunic phagocytes are likely to be the major effector cells in the allorejection reaction. We also propose that the tunic phagocytes are not only the effector cells in the allorejection reaction but also bear the sites of allorecognition.

  2. Looking at both sides of the invasion: patterns of colonization in the violet tunicate Botrylloides violaceus.

    PubMed

    Bock, D G; Zhan, A; Lejeusne, C; MacIsaac, H J; Cristescu, M E

    2011-02-01

    Understanding the ecological and evolutionary forces that shape the genetic structure of invasive populations and facilitate their expansion across a large spectrum of environments is critical for the prediction of spread and management of ongoing invasions. Here, we study the dynamics of postestablishment colonization in the colonial ascidian Botrylloides violaceus, a notorious marine invader. After its initial introduction from the Northwest Pacific, B. violaceus spread rapidly along the Pacific and Atlantic coasts of North America, impacting both aquaculture facilities and natural ecosystems. We compare genetic diversity and patterns of gene flow among 25 populations (N=679) from the West and East coasts, and evaluate the contribution of sexual vs. asexual reproduction to this species' invasion success using data from the mitochondrial cytochrome c oxidase subunit I (COI) gene and 13 nuclear polymorphic microsatellite loci. Our results reveal contrasting patterns of spread in the coastal waters of North America. While the West coast was colonized by noncontiguous (long-distance) dispersal, the East coast invasion appears to have occurred through contiguous (stepping-stone) spread. Molecular data further indicate that although dispersal in colonial ascidians is predominantly achieved through sexually produced propagules, aquaculture practices such as high-pressure washing can facilitate fragmentation and potentially exacerbate infestations and spread via asexual propagules. The results presented here suggest that caution should be used against the general assumption that all invasions, even within a single species, exhibit similar patterns of colonization, as highly contrasting dynamics may transpire in different invaded ranges.

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

    PubMed

    Pennati, R; Dell'Anna, A; Zega, G; De Bernardi, F

    2012-04-20

    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.

  4. Screening for antibacterial and antifungal activities in marine benthic invertebrates from northern Norway.

    PubMed

    Tadesse, Margey; Gulliksen, Bjørn; Strøm, Morten B; Styrvold, Olaf B; Haug, Tor

    2008-11-01

    Benthic marine invertebrates collected from sub-Arctic regions of northern Norway, were found to be a promising source of novel bioactive compounds against human and fish pathogenic bacteria and fungi. Lyophilized material from seven species of ascidians, six sponges and one soft alcyonid coral were extracted with 60% acidified acetonitrile (ACN). After separation into an ACN-rich phase (ACN-extract) and an aqueous phase, and subsequent solid-phase extraction of the aqueous phase, fractions differing in polarity were obtained and screened for antibacterial and antifungal activities, along with the more lipophilic ACN-extracts. Antimicrobial activity was determined against two gram-negative, two gram-positive bacteria, and two strains of fungi. Notably, all the invertebrate species in the study showed activity against all four strains of bacteria and the two strains of fungi. In general, the aqueous fractions displayed highest antimicrobial activity, and the most potent extracts were obtained from the colonial ascidian Synoicum pulmonaria which displayed activity against bacteria and fungi at a concentration of 0.02 mg/ml; the lowest concentration tested.

  5. Colocalization of heparin and histamine in the intracellular granules of test cells from the invertebrate Styela plicata (Chordata-Tunicata).

    PubMed

    Cavalcante, Moisés C M; de Andrade, Leonardo R; Du Bocage Santos-Pinto, Claudia; Straus, Anita H; Takahashi, Hélio K; Allodi, Silvana; Pavão, Mauro S G

    2002-03-01

    In most ascidian species the oocytes are surrounded by two types of accessory cells called follicle cells and test cells. Test cells are located on the periphery of oocytes and remain in the perivitelline space during egg development until hatching. Heparin and histamine were previously described in the test cells of the ascidian Styela plicata. In the present study, electron microscopy techniques were used to characterize the ultrastructure of the S. plicata test cells and to localize heparin and histamine in these cells. Test cells contain several intracellular granules with unique ultrastructural features. They are formed by elongated filaments composed of serial globules with an electron-lucent circle, containing a central electron-dense spot. Immunocytochemistry showed that heparin and histamine colocalize at the border of granule filaments in the test cell. Compound 48/80, a potent secretagogue of heparin-containing mast cells, also induced degranulation of test cells. According to these results, we suggest that test cells represent ancient effector cells of the innate immunity in primitive chordates.

  6. The enigmatic life history of the symbiotic crab Tunicotheres moseri (Crustacea, Brachyura, Pinnotheridae): implications for its mating system and population structure.

    PubMed

    Hernández, J E; Bolaños, J A; Palazón, J L; Hernández, G; Lira, C; Baeza, J Antonio

    2012-12-01

    Resource-monopolization theory predicts the adoption of a solitary habit in species using scarce, discrete, and small refuges. Life-history theory suggests that temporarily stable parental dwellings favor extended parental care in species that brood embryos. We tested these two predictions with the symbiotic crab Tunicotheres moseri. This species exhibits abbreviated development and inhabits the atrial chamber of the scarce, structurally simple, long-lived, and relatively small ascidian Phalusia nigra in the Caribbean. These host characteristics should favor a solitary habit and extended parental care (EPC) in T. moseri. As predicted, males and females of T. moseri inhabited ascidians solitarily with greater frequency than expected by chance alone. The male-female association pattern and reverse sexual dimorphism (males < females) additionally suggests a promiscuous "pure-search" mating system in T. moseri. Also in agreement with theoretical considerations, T. moseri displays EPC; in addition to embryos, females naturally retain larval stages, megalopae, and juveniles within their brooding pouches. This is the first record of EPC in a symbiotic crab and the second confirmed record of EPC in a marine brachyuran crab. This study supports predictions central to resource-monopolization and life-history theories.

  7. Vanadium-Binding Ability of Nucleoside Diphosphate Kinase from the Vanadium-Rich Fan Worm, Pseudopotamilla occelata.

    PubMed

    Yamaguchi, Nobuo; Yoshinaga, Masafumi; Kamino, Kei; Ueki, Tatsuya

    2016-06-01

    Polychaete fan worms and ascidians accumulate high levels of vanadium ions. Several vanadiumbinding proteins, known as vanabins, have been found in ascidians. However, no vanadium-binding factors have been isolated from the fan worm. In the present study, we sought to identify vanadiumbinding proteins in the branchial crown of the fan worm using immobilized metal ion affinity chromatography. A nucleoside diphosphate kinase (NDK) homolog was isolated and determined to be a vanadium-binding protein. Kinase activity of the NDK homologue, PoNDK, was suppressed by the addition of V(IV), but was unaffected by V(V). The effect of V(IV) on PoNDK precedes its activation by Mg(II). This is the first report to describe the relationship between NDK and V(IV). PoNDK is located in the epidermis of the branchial crown, and its distribution is very similar to that of vanadium. These results suggest that PoNDK is associated with vanadium accumulation and metabolism in P. occelata.

  8. Hair cells in non-vertebrate models: lower chordates and molluscs.

    PubMed

    Burighel, P; Caicci, F; Manni, L

    2011-03-01

    The study of hair cells in invertebrates is important, because it can shed light on the debated question about the evolutionary origin of vertebrate hair cells. Here, we review the morphology and significance of hair cells in two groups of invertebrates, the lower chordates (tunicates and cephalochordates) and the molluscs. These taxa possess complex mechanoreceptor organs based on both primary (sensory neurons) and/or secondary, axonless, sensory cells, bearing various apical specializations. Compared with vertebrates, these taxa show interesting examples of convergent evolution and possible homologies of sensory systems. For example, the "lateral line organ" of Octopoda and Decapoda, composed of primary sensory cells aligned on the arms and the head, is considered a classic example of convergent evolution to mechanoreception. Similarly, in ascidians, the cupular organ, formed of primary sensory cells embedded in a gelatinous cupula, is seen as an analog of neuromasts in vertebrates. However, the coronal organ of the oral siphon of ascidians, represented by a line of secondary sensory cells with a hair bundle also comprising graded stereovilli, is currently the best candidate for tracing the evolutionary origin of the vertebrate octavo-lateralis system. Several features, such as embryological origin, position, gene expression and morphology, support this hypothesis.

  9. Porcine relaxin, a 500 million-year-old hormone? the tunicate Ciona intestinalis has porcine relaxin.

    PubMed

    Georges, D; Schwabe, C

    1999-07-01

    The fossil record of tunicates reaches back to the upper Cambrian period. Ascidians have mobile, tadpole-like juvenile forms with a notochord, which inspired the classification of tunicates as Urochordata, i.e., predecessors of vertebrates. The genome of the tunicate Ciona intestinalis contains a relaxin coding region that is organized like a mammalian gene, i.e., signal peptide, B-chain domain, connecting peptide domain, followed by the A-chain domain with a stop codon after cysteine A-22. RNA-derived cDNA encodes a relaxin that is identical to the circulating form of the porcine hormone. In contrast to the porcine gene, the ascidian gene has no intron in the C-peptide domain, and in that respect is similar to the bombyxin gene of the silkworm. During the spawning period, only enough relaxin could be extracted and isolated from gonads of C. intestinalis for a partial sequence analysis. Remarkable as it may be, these findings suggest that relaxin is identical in pigs, whales, and the tunicate C. intestinalis.

  10. Early Chordate Origin of the Vertebrate Integrin αI Domains

    PubMed Central

    Chouhan, Bhanupratap Singh; Käpylä, Jarmo; Denessiouk, Konstantin; Denesyuk, Alexander; Heino, Jyrki; Johnson, Mark S.

    2014-01-01

    Half of the 18 human integrins α subunits have an inserted αI domain yet none have been observed in species that have diverged prior to the appearance of the urochordates (ascidians). The urochordate integrin αI domains are not human orthologues but paralogues, but orthologues of human αI domains extend throughout later-diverging vertebrates and are observed in the bony fish with duplicate isoforms. Here, we report evidence for orthologues of human integrins with αI domains in the agnathostomes (jawless vertebrates) and later diverging species. Sequence comparisons, phylogenetic analyses and molecular modeling show that one nearly full-length sequence from lamprey and two additional fragments include the entire integrin αI domain region, have the hallmarks of collagen-binding integrin αI domains, and we show that the corresponding recombinant proteins recognize the collagen GFOGER motifs in a metal dependent manner, unlike the α1I domain of the ascidian C. intestinalis. The presence of a functional collagen receptor integrin αI domain supports the origin of orthologues of the human integrins with αI domains prior to the earliest diverging extant vertebrates, a domain that has been conserved and diversified throughout the vertebrate lineage. PMID:25409021

  11. Expression of the amphioxus Pit-1 gene (AmphiPOU1F1/Pit-1) exclusively in the developing preoral organ, a putative homolog of the vertebrate adenohypophysis.

    PubMed

    Candiani, Simona; Holland, Nicholas D; Oliveri, Diana; Parodi, Manuela; Pestarino, Mario

    2008-03-18

    For the Florida amphioxus (Branchiostoma floridae), the full-length sequence and developmental expression of AmphiPOU1F1/Pit-1 are described. This gene, which is present in a single copy in the genome, is homologous to Pit-1 genes of vertebrates that play key roles in the development of the adenohypophysis. During amphioxus development, AmphiPOU1F1/Pit-1 transcripts are limited to Hatschek's left diverticulum and the larval tissue developing from it--namely the concave portion of the preoral organ. No other expression domains for this gene were detected during embryonic and larval development. From data currently available for hemichordates, amphioxus and ascidians, the best supported homologs for the vertebrate adenohypophysis are the preoral ciliary organ of hemichordates, preoral organ/Hatschek's pit of amphioxus and the neural gland/duct complex of ascidians. Better insights into pituitary evolution will require additional information: for invertebrate deuterostomes, more of the key pituitary genes in hemichordates and tunicates need to be studied; for the more basal groups vertebrates, it will be important to determine whether the source of the adenohypophysis is endodermal or ectodermal and to demonstrate what, if any, contribution mesodermal head coeloms might make to the developing pituitary.

  12. Transmission and Scanning Electron Microscopy of the Accessory Cells and Chorion During Development of Ciona intestinalis Type B Embryos and the Impact of Their Removal on Cell Morphology.

    PubMed

    Thompson, Helen; Shimeld, Sebastian M

    2015-06-01

    Spawned ascidian oocytes are surrounded by a membrane called the chorion (or vitelline coat) and associated with two populations of maternally-supplied cells. Outside the chorion are follicle cells, which may affect the buoyancy of eggs. Inside the chorion are test cells, which during oogenesis provision the egg and which after fertilisation contribute to the larval tunic. The structure of maternal cells may vary between species. The model ascidian Ciona intestinalis has been recently split into two species, currently named type A and type B. The ultrastructure of extraembryonic cells and structures from type A embryos has been reported. Here we describe the ultrastructure of follicle and test cells from C. intestinalis type B embryos. Test cells are about 5 µm in diameter and line the inside of the chorion of developing embryos in a dense sheet. Follicle cells are large (> 100 µm long) and spike-shaped, with many large vesicles. Terminal electron dense granules are found towards the tips of spikes, adjacent to cytoplasm containing numerous small electron dense bodies connected by filaments. These are probably vesicles containing material for the terminal granules. Removal of maternal structures and cells just after fertilisation, as commonly used in many experiments manipulating C. intestinalis development, has been reported to affect embryonic patterning. We examined the impact of this on embryonic ectoderm cells by scanning electron microscopy. Cells of embryos that developed without maternal structures still developed cilia, but had indistinct cell boundaries and a more flattened appearance than those that developed within the chorion.

  13. Eukaryotic UDP-galactopyranose mutase (GLF gene) in microbial and metazoal pathogens.

    PubMed

    Beverley, Stephen M; Owens, Katherine L; Showalter, Melissa; Griffith, Cara L; Doering, Tamara L; Jones, Victoria C; McNeil, Michael R

    2005-06-01

    Galactofuranose (Gal(f)) is a novel sugar absent in mammals but present in a variety of pathogenic microbes, often within glycoconjugates that play critical roles in cell surface formation and the infectious cycle. In prokaryotes, Gal(f) is synthesized as the nucleotide sugar UDP-Gal(f) by UDP-galactopyranose mutase (UGM) (gene GLF). Here we used a combinatorial bioinformatics screen to identify a family of candidate eukaryotic GLFs that had previously escaped detection. GLFs from three pathogens, two protozoa (Leishmania major and Trypanosoma cruzi) and one fungus (Cryptococcus neoformans), had UGM activity when expressed in Escherichia coli and assayed in vivo and/or in vitro. Eukaryotic GLFs are closely related to each other but distantly related to prokaryotic GLFs, showing limited conservation of core residues around the substrate-binding site and flavin adenine dinucleotide binding domain. Several eukaryotes not previously investigated for Gal(f) synthesis also showed strong GLF homologs with conservation of key residues. These included other fungi, the alga Chlamydomonas and the algal phleovirus Feldmannia irregularis, parasitic nematodes (Brugia, Onchocerca, and Strongyloides) and Caenorhabditis elegans, and the urochordates Halocynthia and Cionia. The C. elegans open reading frame was shown to encode UGM activity. The GLF phylogenetic distribution suggests that Gal(f) synthesis may occur more broadly in eukaryotes than previously supposed. Overall, GLF/Gal(f) synthesis in eukaryotes appears to occur with a disjunct distribution and often in pathogenic species, similar to what is seen in prokaryotes. Thus, UGM inhibition may provide an attractive drug target in those eukaryotes where Gal(f) plays critical roles in cellular viability and virulence.

  14. Incremental evolution of the neural crest, neural crest cells and neural crest-derived skeletal tissues.

    PubMed

    Hall, Brian K; Gillis, J Andrew

    2013-01-01

    Urochordates (ascidians) have recently supplanted cephalochordates (amphioxus) as the extant sister taxon of vertebrates. Given that urochordates possess migratory cells that have been classified as 'neural crest-like'- and that cephalochordates lack such cells--this phylogenetic hypothesis may have significant implications with respect to the origin of the neural crest and neural crest-derived skeletal tissues in vertebrates. We present an overview of the genes and gene regulatory network associated with specification of the neural crest in vertebrates. We then use these molecular data--alongside cell behaviour, cell fate and embryonic context--to assess putative antecedents (latent homologues) of the neural crest or neural crest cells in ascidians and cephalochordates. Ascidian migratory mesenchymal cells--non-pigment-forming trunk lateral line cells and pigment-forming 'neural crest-like cells' (NCLC)--are unlikely latent neural crest cell homologues. Rather, Snail-expressing cells at the neural plate of border of urochordates and cephalochordates likely represent the extent of neural crest elaboration in non-vertebrate chordates. We also review evidence for the evolutionary origin of two neural crest-derived skeletal tissues--cartilage and dentine. Dentine is a bona fide vertebrate novelty, and dentine-secreting odontoblasts represent a cell type that is exclusively derived from the neural crest. Cartilage, on the other hand, likely has a much deeper origin within the Metazoa. The mesodermally derived cellular cartilages of some protostome invertebrates are much more similar to vertebrate cartilage than is the acellular 'cartilage-like' tissue in cephalochordate pharyngeal arches. Cartilage, therefore, is not a vertebrate novelty, and a well-developed chondrogenic program was most likely co-opted from mesoderm to the neural crest along the vertebrate stem. We conclude that the neural crest is a vertebrate novelty, but that neural crest cells and their

  15. Cryptic speciation or global spread? The case of a cosmopolitan marine invertebrate with limited dispersal capabilities

    PubMed Central

    R., Pérez-Portela; V., Arranz; M., Rius; X., Turon

    2013-01-01

    The existence of globally-distributed species with low dispersal capabilities is a paradox that has been explained as a result of human-mediated transport and by hidden diversity in the form of unrecognized cryptic species. Both factors are not mutually exclusive, but relatively few studies have demonstrated the presence of both. Here we analyse the genetic patterns of the colonial ascidian Diplosoma listerianum, a species nowadays distributed globally. The study of a fragment of a mitochondrial gene in localities worldwide revealed the existence of multiple cryptic species. In addition, we found a complex geographic structure and multiple clades occurred in sympatry. One of the species showed strong population structure irrespective of geographical distances, which is coherent with stochastic dispersal linked to human transport. The present study shows the complexity of discerning the role of cryptic diversity from human-driven range shifts worldwide, as well as disentangling the effects of natural and artificial dispersal. PMID:24217373

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

    PubMed

    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.

  17. Identification of a retinoic acid-responsive neural enhancer in the Ciona intestinalis Hox1 gene.

    PubMed

    Kanda, Miyuki; Ikeda, Taku; Fujiwara, Shigeki

    2013-02-01

    The Hox1 gene in the urochordate ascidian Ciona intestinalis (Ci-Hox1) is expressed in the nerve cord and epidermis. We identified a nerve cord enhancer in the second intron of Ci-Hox1, and demonstrated that retinoic acid (RA) plays a major role in activating this enhancer. The enhancer contained a putative retinoic acid-response element (RARE). Mutation of the RARE in the Ci-Hox1 nerve cord enhancer only partially abolished the enhancer activity. Genes encoding RA synthase and the RA receptor were knocked down using specific antisense morpholino oligos (MOs), and injection of embryos with these MOs resulted in the complete disappearance of epidermal expression of Ci-Hox1 and reduction of neural expression. However, nerve cord expression was not completely repressed. These results suggest that the nerve cord enhancer is activated by two partially redundant pathways; one RA-dependent and one RA-independent.

  18. Population dynamics and reproductive patterns of boltenia echinata (Ascidicea) on the Swedish west coast

    NASA Astrophysics Data System (ADS)

    Svane, I.; Lundälv, T.

    Two populations of Boltenia echinata on the Swedish west coast were studied over a 10-year period by stereo-photographic recording of subtidal, vertical rock wallsat a depth of 20 m. Supplemental sampling was carried out over a one-year period. On the sheltered population decreased in numbers with an explosive increase in Ciona intestinalis. Another, exposed population displayed a similar response at the increase of annual ascidians ( Ascidiella scabra, A. aspersa and Corella parallelogramma). Variations in recruitment were influenced by interference competition, while adults were affected to a lesser extent. Recruitment and mortality at the exposed locality were twice as high as at the sheltered locality whereas the mean annual mortality pattern was similar. Adult mortality was related to physical factors (mainly temperature), imposing stresses of different magnitudes on the two populations. Settling and recruitment was observed throghout the year. No relation was found between the presence of incubating embryos or larvae in the atrial cavity and settling.

  19. Upregulated transcription of phenoloxidase genes in the pharynx and endostyle of Ciona intestinalis in response to LPS.

    PubMed

    Vizzini, Aiti; Parrinello, Daniela; Sanfratello, Maria Antonietta; Trapani, Maria Rosa; Mangano, Valentina; Parrinello, Nicolò; Cammarata, Matteo

    2015-03-01

    We investigated the role of phenoloxidases (POs) in ascidians inflammatory reaction, a components of a copper-containing protein family involved in invertebrate immune system. In Ciona intestinalis two phenoloxidases (CinPO-1, CinPO-2) have been sequenced. In the present study, real time PCR analysis showed that both CinPO-1 and CinPO-2 genes were modulated by LPS inoculation suggesting that they are inducible and highly expressed in the inflamed pharynx. In situ hybridization disclosed CinPO-1 and CinPO-2 transcripts in pharynx hemocytes (granulocytes) and, mainly, in unilocular refractile granulocytes (URG) which mainly populated the inflamed tunic matrix. Interestingly, the genes are also upregulated by LPS in the endostyle (zones 7, 8 and 9) that is considered homolog to the vertebrate thyroid.

  20. Ciona intestinalis interleukin 17-like genes expression is upregulated by LPS challenge.

    PubMed

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

    2015-01-01

    In humans, IL-17 is a proinflammatory cytokine that plays a key role in the clearance of extracellular bacteria promoting cell infiltration and production of several cytokines and chemokines. Here, we report on three Ciona intestinalis IL-17 homologues (CiIL17-1, CiIL17-2, CiIL17-3). The gene organization, phylogenetic tree and modeling supported the close relationship with the mammalian IL-17A and IL-17F suggesting that the C. intestinalis IL-17 genes share a common ancestor in the chordate lineages. Real time PCR analysis showed a prompt expression induced by LPS inoculation suggesting that they are involved in the first phase of inflammatory response. In situ hybridization assays disclosed that the genes transcription was upregulated in the pharynx, the main organ of the ascidian immune system, and expressed by hemocytes (granulocytes and univacuolar refractile granulocyte) inside the pharynx vessels.

  1. Phallusiasterols A and B: two new sulfated sterols from the Mediterranean tunicate Phallusia fumigata and their effects as modulators of the PXR receptor.

    PubMed

    Imperatore, Concetta; D'Aniello, Filomena; Aiello, Anna; Fiorucci, Stefano; D'Amore, Claudio; Sepe, Valentina; Menna, Marialuisa

    2014-04-03

    Purification of the apolar extracts of the marine ascidian Phallusia fumigata, afforded two new sulfated sterols, phallusiasterols A (1) and B (2). The structures of the new compounds have been elucidated using mass spectrometry and NMR experiments. The effects of phallusiasterols A and B as modulators of pregnane-X-receptor (PXR) have been investigated. These studies revealed that phallusiasterol A induces PXR transactivation in HepG2 cells and stimulates the expression of the PXR target genes CYP3A4 and MDR1 in the same cell line. Molecular docking calculations suggested the theoretical binding mode of phallusiasterol A with hPXR and revealed that phallusiasterol A fitted well in the LBD of PXR.

  2. Guidelines for the nomenclature of genetic elements in tunicate genomes.

    PubMed

    Stolfi, Alberto; Sasakura, Yasunori; Chalopin, Domitille; Satou, Yutaka; Christiaen, Lionel; Dantec, Christelle; Endo, Toshinori; Naville, Magali; Nishida, Hiroki; Swalla, Billie J; Volff, Jean-Nicolas; Voskoboynik, Ayelet; Dauga, Delphine; Lemaire, Patrick

    2015-01-01

    Tunicates are invertebrate members of the chordate phylum, and are considered to be the sister group of vertebrates. Tunicates are composed of ascidians, thaliaceans, and appendicularians. With the advent of inexpensive high-throughput sequencing, the number of sequenced tunicate genomes is expected to rise sharply within the coming years. To facilitate comparative genomics within the tunicates, and between tunicates and vertebrates, standardized rules for the nomenclature of tunicate genetic elements need to be established. Here we propose a set of nomenclature rules, consensual within the community, for predicted genes, pseudogenes, transcripts, operons, transcriptional cis-regulatory regions, transposable elements, and transgenic constructs. In addition, the document proposes guidelines for naming transgenic and mutant lines.

  3. Whole-mount fluorescent in situ hybridization staining of the colonial tunicate Botryllus schlosseri.

    PubMed

    Langenbacher, Adam D; Rodriguez, Delany; Di Maio, Alessandro; De Tomaso, Anthony W

    2015-01-01

    Botryllus schlosseri is a colonial ascidian with characteristics that make it an attractive model for studying immunology, stem cell biology, evolutionary biology, and regeneration. Transcriptome sequencing and the recent completion of a draft genome sequence for B. schlosseri have revealed a large number of genes, both with and without vertebrate homologs, but analyzing the spatial and temporal expression of these genes in situ has remained a challenge. Here, we report a robust protocol for in situ hybridization that enables the simultaneous detection of multiple transcripts in whole adult B. schlosseri using Tyramide Signal Amplification in conjunction with digoxigenin- and dinitrophenol-labeled RNA probes. Using this protocol, we have identified a number of genes that can serve as markers for developing and mature structures in B. schlosseri, permitting analysis of phenotypes induced in loss-of-function experiments.

  4. Diversity of Nonribosomal Peptide Synthetase Genes in the Microbial Metagenomes of Marine Sponges

    PubMed Central

    Pimentel-Elardo, Sheila Marie; Grozdanov, Lubomir; Proksch, Sebastian; Hentschel, Ute

    2012-01-01

    Genomic mining revealed one major nonribosomal peptide synthetase (NRPS) phylogenetic cluster in 12 marine sponge species, one ascidian, an actinobacterial isolate and seawater. Phylogenetic analysis predicts its taxonomic affiliation to the actinomycetes and hydroxy-phenyl-glycine as a likely substrate. Additionally, a phylogenetically distinct NRPS gene cluster was discovered in the microbial metagenome of the sponge Aplysina aerophoba, which shows highest similarities to NRPS genes that were previously assigned, by ways of single cell genomics, to a Chloroflexi sponge symbiont. Genomic mining studies such as the one presented here for NRPS genes, contribute to on-going efforts to characterize the genomic potential of sponge-associated microbiota for secondary metabolite biosynthesis. PMID:22822366

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

    PubMed Central

    Martins, Joana; Vasconcelos, Vitor

    2015-01-01

    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. PMID:26580631

  6. Clinical marine toxicology: a European perspective for clinical toxicologists and poison centers.

    PubMed

    Schmitt, Corinne; De Haro, Luc

    2013-08-02

    Clinical marine toxicology is a rapidly changing area. Many of the new discoveries reported every year in Europe involve ecological disturbances--including global warming--that have induced modifications in the chorology, behavior, and toxicity of many species of venomous or poisonous aquatic life including algae, ascidians, fish and shellfish. These changes have raised a number of public issues associated, e.g., poisoning after ingestion of contaminated seafood, envenomation by fish stings, and exposure to harmful microorganism blooms. The purpose of this review of medical and scientific literature in marine toxicology is to highlight the growing challenges induced by ecological disturbances that confront clinical toxicologists during the everyday job in the European Poison Centers.

  7. Phallusiasterols A and B: Two New Sulfated Sterols from the Mediterranean Tunicate Phallusia fumigata and Their Effects as Modulators of the PXR Receptor

    PubMed Central

    Imperatore, Concetta; D’Aniello, Filomena; Aiello, Anna; Fiorucci, Stefano; D’Amore, Claudio; Sepe, Valentina; Menna, Marialuisa

    2014-01-01

    Purification of the apolar extracts of the marine ascidian Phallusia fumigata, afforded two new sulfated sterols, phallusiasterols A (1) and B (2). The structures of the new compounds have been elucidated using mass spectrometry and NMR experiments. The effects of phallusiasterols A and B as modulators of pregnane-X-receptor (PXR) have been investigated. These studies revealed that phallusiasterol A induces PXR transactivation in HepG2 cells and stimulates the expression of the PXR target genes CYP3A4 and MDR1 in the same cell line. Molecular docking calculations suggested the theoretical binding mode of phallusiasterol A with hPXR and revealed that phallusiasterol A fitted well in the LBD of PXR. PMID:24705503

  8. Clinical Marine Toxicology: A European Perspective for Clinical Toxicologists and Poison Centers

    PubMed Central

    Schmitt, Corinne; de Haro, Luc

    2013-01-01

    Clinical marine toxicology is a rapidly changing area. Many of the new discoveries reported every year in Europe involve ecological disturbances—including global warming—that have induced modifications in the chorology, behavior, and toxicity of many species of venomous or poisonous aquatic life including algae, ascidians, fish and shellfish. These changes have raised a number of public issues associated, e.g., poisoning after ingestion of contaminated seafood, envenomation by fish stings, and exposure to harmful microorganism blooms. The purpose of this review of medical and scientific literature in marine toxicology is to highlight the growing challenges induced by ecological disturbances that confront clinical toxicologists during the everyday job in the European Poison Centers. PMID:23917333

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

    PubMed

    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.

  10. Guidelines for the Nomenclature of Genetic Elements in Tunicate Genomes

    PubMed Central

    Stolfi, Alberto; Sasakura, Yasunori; Chalopin, Domitille; Satou, Yutaka; Christiaen, Lionel; Dantec, Christelle; Endo, Toshinori; Naville, Magali; Nishida, Hiroki; Swalla, Billie J.; Volff, Jean-Nicolas; Voskoboynik, Ayelet; Dauga, Delphine; Lemaire, Patrick

    2014-01-01

    Summary Tunicates are invertebrate members of the chordate phylum, and are considered to be the sister group of vertebrates. Tunicates are composed of ascidians, thaliaceans, and appendicularians. With the advent of inexpensive high-throughput sequencing, the number of sequenced tunicate genomes is expected to rise sharply within the coming years. To facilitate comparative genomics within the tunicates, and between tunicates and vertebrates, standardized rules for the nomenclature of tunicate genetic elements need to be established. Here we propose a set of nomenclature rules, consensual within the community, for predicted genes, pseudogenes, transcripts, operons, transcriptional cis-regulatory regions, transposable elements, and transgenic constructs. In addition, the document proposes guidelines for naming transgenic and mutant lines. PMID:25220678

  11. Did the first chordates organize without the organizer?

    PubMed

    Kourakis, Matthew J; Smith, William C

    2005-09-01

    Models of vertebrate development frequently portray the organizer as acting on a largely unpatterned embryo to induce major components of the body plan, such as the neural plate and somites. Recent experiments examining the molecular and genetic basis of major inductive events of vertebrate embryogenesis force a re-examination of this view. These newer observations, along with a proposed revised fate map for the frog Xenopus laevis, suggest a possible reconciliation between the seemingly disparate mechanisms present in the ontogeny of the common chordate body plan of vertebrate and invertebrate chordates. Here, we review data from vertebrates and from an ascidian urochordate and propose that the organizer was not present at the base of the chordate lineage, but could have been a later innovation in the lineage leading to vertebrates, where its role was more permissive than instructive.

  12. Reduction of vanadium(V) to vanadium(IV) by NADPH, and vanadium(IV) to vanadium(III) by cysteine methyl ester in the presence of biologically relevant ligands.

    PubMed

    Islam, Mohammad K; Tsuboya, Chieko; Kusaka, Hiroko; Aizawa, Sen-ichi; Ueki, Tatsuya; Michibata, Hitoshi; Kanamori, Kan

    2007-08-01

    To better understand the mechanism of vanadium reduction in ascidians, we examined the reduction of vanadium(V) to vanadium(IV) by NADPH and the reduction of vanadium(IV) to vanadium(III) by L-cysteine methyl ester (CysME). UV-vis and electron paramagnetic resonance spectroscopic studies indicated that in the presence of several biologically relevant ligands vanadium(V) and vanadium(IV) were reduced by NADPH and CysME, respectively. Specifically, NADPH directly reduced vanadium(V) to vanadium(IV) with the assistance of ligands that have a formation constant with vanadium(IV) of greater than 7. Also, glycylhistidine and glycylaspartic acid were found to assist the reduction of vanadium(IV) to vanadium(III) by CysME.

  13. An organismal perspective on C. intestinalis development, origins and diversification

    PubMed Central

    Kourakis, Matthew J; Smith, William C

    2015-01-01

    The ascidian Ciona intestinalis, commonly known as a ‘sea squirt’, has become an important model for embryological studies, offering a simple blueprint for chordate development. As a model organism, it offers the following: a small, compact genome; a free swimming larva with only about 2600 cells; and an embryogenesis that unfolds according to a predictable program of cell division. Moreover, recent phylogenies reveal that C. intestinalis occupies a privileged branch in the tree of life: it is our nearest invertebrate relative. Here, we provide an organismal perspective of C. intestinalis, highlighting aspects of its life history and habitat—from its brief journey as a larva to its radical metamorphosis into adult form—and relate these features to its utility as a laboratory model. DOI: http://dx.doi.org/10.7554/eLife.06024.001 PMID:25807088

  14. [Morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates].

    PubMed

    Isaeva, V V; Akhmadieva, A V; Aleksandriova, Ia N; Shukaliuk, A I

    2009-01-01

    Published and original data indicating evolutionary conservation of the morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates are reviewed. Stem cells were studied in representatives of five animal types: archeocytes in sponge Oscarella malakhovi (Porifera), large interstitial cells in colonial hydroid Obelia longissima (Cnidaria), neoblasts in an asexual race of planarian Girardia tigrina (Platyhelmintes), stem cells in colonial rhizocephalans Peltogasterella gracilis, Polyascus polygenea, and Thylacoplethus isaevae (Arthropoda), and colonial ascidian Botryllus tuberatus (Chordata). Stem cells in animals of such diverse taxa feature the presence of germinal granules, are positive for proliferating cell nuclear antigen, demonstrate alkaline phosphatase activity (at marker of embryonic stem cells and primary germ cells in vertebrates), and rhizocephalan stem cells express the vasa-like gene (such genes are expressed in germline cells of different metazoans). The self-renewing pool of stem cells is the cellular basis of the reproductive strategy including sexual and asexual reproduction.

  15. Ciona as a Simple Chordate Model for Heart Development and Regeneration

    PubMed Central

    Anderson, Heather Evans; Christiaen, Lionel

    2016-01-01

    Cardiac cell specification and the genetic determinants that govern this process are highly conserved among Chordates. Recent studies have established the importance of evolutionarily-conserved mechanisms in the study of congenital heart defects and disease, as well as cardiac regeneration. As a basal Chordate, the Ciona model system presents a simple scaffold that recapitulates the basic blueprint of cardiac development in Chordates. Here we will focus on the development and cellular structure of the heart of the ascidian Ciona as compared to other Chordates, principally vertebrates. Comparison of the Ciona model system to heart development in other Chordates presents great potential for dissecting the genetic mechanisms that underlie congenital heart defects and disease at the cellular level and might provide additional insight into potential pathways for therapeutic cardiac regeneration. PMID:27642586

  16. An Early Cambrian tunicate from China.

    PubMed

    Shu, D G; Chen, L; Han, J; Zhang, X L

    2001-05-24

    Like the Burgess Shales of Canada, the Chengjiang Lagerstätte from the Lower Cambrian of China is renowned for the detailed preservation as fossils of delicate, soft-bodied creatures, providing an insight into the Cambrian explosion. The fossils of possible hemichordate chordates and vertebrates have attracted particular attention. Tunicates, or urochordates, comprise the most basal chordate clade, and details of their evolution could be important in understanding the sequence of character acquisition that led to the emergence of chordates and vertebrates. However, definitive fossils of tunicates from the Cambrian are scarce or debatable. Here we report a probable tunicate Cheungkongella ancestralis from the Chengjiang fauna. It resembles the extant ascidian tunicate genus Styela whose morphology could be useful in understanding the origin of the vertebrates.

  17. Mycalamide A Shows Cytotoxic Properties and Prevents EGF-Induced Neoplastic Transformation through Inhibition of Nuclear Factors

    PubMed Central

    Dyshlovoy, Sergey A.; Fedorov, Sergey N.; Kalinovsky, Anatoly I.; Shubina, Larisa K.; Bokemeyer, Carsten; Stonik, Valentin A.; Honecker, Friedemann

    2012-01-01

    Mycalamide A, a marine natural compound previously isolated from sponges, is known as a protein synthesis inhibitor with potent antitumor activity. However, the ability of this compound to prevent malignant transformation of cells has never been examined before. Here, for the first time, we report the isolation of mycalamide A from ascidian Polysincraton sp. as well as investigation of its cancer preventive properties. In murine JB6 Cl41 P+ cells, mycalamide A inhibited epidermal growth factor (EGF)-induced neoplastic transformation, and induced apoptosis at subnanomolar or nanomolar concentrations. The compound inhibited transcriptional activity of the oncogenic nuclear factors AP-1 and NF-κB, a potential mechanism of its cancer preventive properties. Induction of phosphorylation of the kinases MAPK p38, JNK, and ERK was also observed at high concentrations of mycalamide A. The drug shows promising potential for both cancer-prevention and cytotoxic therapy and should be further developed. PMID:22822368

  18. Developmental Control of Cell-Cycle Compensation Provides a Switch for Patterned Mitosis at the Onset of Chordate Neurulation.

    PubMed

    Ogura, Yosuke; Sasakura, Yasunori

    2016-04-18

    During neurulation of chordate ascidians, the 11th mitotic division within the epidermal layer shows a posterior-to-anterior wave that is precisely coordinated with the unidirectional progression of the morphogenetic movement. Here we show that the first sign of this patterned mitosis is an asynchronous anterior-to-posterior S-phase length and that mitotic synchrony is reestablished by a compensatory asynchronous G2-phase length. Live imaging combined with genetic experiments demonstrated that compensatory G2-phase regulation requires transcriptional activation of the G2/M regulator cdc25 by the patterning genes GATA and AP-2. The downregulation of GATA and AP-2 at the onset of neurulation leads to loss of compensatory G2-phase regulation and promotes the transition to patterned mitosis. We propose that such developmentally regulated cell-cycle compensation provides an abrupt switch to spatially patterned mitosis in order to achieve the coordination between mitotic timing and morphogenesis.

  19. The significance of Ciona intestinalis as a stem organism in integrative studies of functional evolution of the chordate endocrine, neuroendocrine, and nervous systems.

    PubMed

    Matsubara, Shin; Kawada, Tsuyoshi; Sakai, Tsubasa; Aoyama, Masato; Osugi, Tomohiro; Shiraishi, Akira; Satake, Honoo

    2016-02-01

    Ascidians are the closest phylogenetic neighbors to vertebrates and are believed to conserve the evolutionary origin in chordates of the endocrine, neuroendocrine, and nervous systems involving neuropeptides and peptide hormones. Ciona intestinalis harbors various homologs or prototypes of vertebrate neuropeptides and peptide hormones including gonadotropin-releasing hormones (GnRHs), tachykinins (TKs), and calcitonin, as well as Ciona-specific neuropeptides such as Ciona vasopressin, LF, and YFV/L peptides. Moreover, molecular and functional studies on Ciona tachykinin (Ci-TK) have revealed the novel molecular mechanism of inducing oocyte growth via up-regulation of vitellogenesis-associated protease activity, which is expected to be conserved in vertebrates. Furthermore, a series of studies on Ciona GnRH receptor paralogs have verified the species-specific regulation of GnRHergic signaling including unique signaling control via heterodimerization among multiple GnRH receptors. These findings confirm the remarkable significance of ascidians in investigations of the evolutionary processes of the peptidergic systems in chordates, leading to the promising advance in the research on Ciona peptides in the next stage based on the recent development of emerging technologies including genome-editing techniques, peptidomics-based multi-color staining, machine-learning prediction, and next-generation sequencing. These technologies and bioinformatic integration of the resultant "multi-omics" data will provide unprecedented insights into the comprehensive understanding of molecular and functional regulatory mechanisms of the Ciona peptides, and will eventually enable the exploration of both conserved and diversified endocrine, neuroendocrine, and nervous systems in the evolutionary lineage of chordates.

  20. The role of vanadium in the chemical defense of the solitary tunicate, Phallusia nigra.

    PubMed

    Odate, Shobu; Pawlik, Joseph R

    2007-03-01

    Ascidians (sea squirts) may defend themselves from predators, biofouling competitors, and bacterial infection by producing secondary metabolites or sequestering acid, but many species also accumulate heavy metals, most notably vanadium. The defensive functions of heavy metals in ascidians remain unclear, and to this end, the solitary Caribbean tunicate, Phallusia nigra, was studied to localize vanadium in its tissues and to assess the defensive properties of vanadium-containing compounds. As determined by flame atomic absorption spectroscopy, the internal tissues and blood contained the highest vanadium concentrations (mean values of 2280 and 1886 ppm dry mass, respectively), followed by the tunic surface (871 ppm dry mass). Results of laboratory feeding assays with the bluehead wrasse, Thalassoma bifasciatum, confirmed outcomes of past studies that demonstrated that vanadyl sulfate (VOSO4.6H20) and sodium vanadate (Na3VO4) were unpalatable to fish, although these salts do not accurately reflect the chelation environment or oxidation state of vanadium in living tunicates. Fresh preparations of whole tunic, internal tissues, and blood were unpalatable to fish, but freezing and thawing of internal tissues and blood rendered them palatable. Crude organic extracts of whole tunic and internal tissues contained vanadium metabolites (225 and 750 ppm dry mass, respectively) and were palatable to T. bifasciatum; crude extracts also exhibited no antimicrobial effects against a panel of four marine bacteria known to be pathogens of marine invertebrates (Vibrio parahaemolyticus, Vibrio harveyi, Leucothrix mucor, and Deleya marina). Nonacidic vanadium (+3) complexes neither deterred predation nor inhibited microbial growth, whereas acidic aqua vanadium (+3 and +4) complexes were unpalatable to 7 bifasciatum and exhibited antimicrobial activity. Difficulties in decoupling low pH from oxidation state and chelation environment of vanadium prevent definitive conclusions about the

  1. Real-time PCR detection of Didemnum perlucidum (Monniot, 1983) and Didemnum vexillum (Kott, 2002) in an applied routine marine biosecurity context.

    PubMed

    Simpson, Tiffany J S; Dias, P Joana; Snow, Michael; Muñoz, Julieta; Berry, Tina

    2016-08-02

    Prevention and early detection are well recognized as the best strategies for minimizing the risks posed by nonindigenous species (NIS) that have the potential to become marine pests. Central to this is the ability to rapidly and accurately identify the presence of NIS, often from complex environmental samples like biofouling and ballast water. Molecular tools have been increasingly applied to assist with the identification of NIS and can prove particularly useful for taxonomically difficult groups like ascidians. In this study, we have developed real-time PCR assays suited to the specific identification of the ascidians Didemnum perlucidum and Didemnum vexillum. Despite being recognized as important global pests, this is the first time specific molecular detection methods have been developed that can support the early identification and detection of these species from a broad range of environmental sample types. These fast, robust and high-throughput assays represent powerful tools for routine marine biosecurity surveillance, as detection and confirmation of the early presence of species could assist in the timely establishment of emergency responses and control strategies. This study applied the developed assays to confirm the ability to detect Didemnid eDNA in water samples. While previous work has focused on detection of marine larvae from water samples, the development of real-time PCR assays specifically aimed at detecting eDNA of sessile invertebrate species in the marine environment represents a world first and a significant step forwards in applied marine biosecurity surveillance. Demonstrated success in the detection of D. perlucidum eDNA from water samples at sites where it could not be visually identified suggests value in incorporating such assays into biosecurity survey designs targeting Didemnid species.

  2. Functional specialization of cellulose synthase genes of prokaryotic origin in chordate larvaceans.

    PubMed

    Sagane, Yoshimasa; Zech, Karin; Bouquet, Jean-Marie; Schmid, Martina; Bal, Ugur; Thompson, Eric M

    2010-05-01

    Extracellular matrices play important, but poorly investigated, roles in morphogenesis. Extracellular cellulose is central to regulation of pattern formation in plants, but among metazoans only tunicates are capable of cellulose biosynthesis. Cellulose synthase (CesA) gene products are present in filter-feeding structures of all tunicates and also regulate metamorphosis in the ascidian Ciona. Ciona CesA is proposed to have been acquired by lateral gene transfer from a prokaryote. We identified two CesA genes in the sister-class larvacean Oikopleura dioica. Each has a mosaic structure of a glycoslyltransferase 2 domain upstream of a glycosyl hydrolase family 6 cellulase-like domain, a signature thus far unique to tunicates. Spatial-temporal expression analysis revealed that Od-CesA1 produces long cellulose fibrils along the larval tail, whereas Od-CesA2 is responsible for the cellulose scaffold of the post-metamorphic filter-feeding house. Knockdown of Od-CesA1 inhibited cellulose production in the extracellular matrix of the larval tail. Notochord cells either failed to align or were misaligned, the tail did not elongate properly and tailbud embryos also exhibited a failure to hatch. Knockdown of Od-CesA2 did not elicit any of these phenotypes and instead caused a mild delay in pre-house formation. Phylogenetic analyses including Od-CesAs indicate that a single lateral gene transfer event from a prokaryote at the base of the lineage conferred biosynthetic capacity in all tunicates. Ascidians possess one CesA gene, whereas duplicated larvacean genes have evolved distinct temporal and functional specializations. Extracellular cellulose microfibrils produced by the pre-metamorphic Od-CesA1 duplicate have a role in notochord and tail morphogenesis.

  3. Sperm motility parameters and spermatozoa morphometric characterization in marine species: a study of swimmer and sessile species.

    PubMed

    Gallego, V; Pérez, L; Asturiano, J F; Yoshida, M

    2014-09-15

    The biodiversity of marine ecosystems is diverse and a high number of species coexist side by side. However, despite the fact that most of these species share a common fertilization strategy, a high variability in terms of the size, shape, and motion of spermatozoa can be found. In this study, we have analyzed both the sperm motion parameters and the spermatozoa morphometric features of two swimmer (pufferfish and European eel) and two sessile (sea urchin and ascidian) marine species. The most important differences in the sperm motion parameters were registered in the swimming period. Sessile species sperm displayed notably higher values than swimmer species sperm. In addition, the sperm motilities and velocities of the swimmer species decreased sharply once the sperm was activated, whereas the sessile species were able to maintain their initial values for a long time. These results are linked directly to the species-specific lifestyles. Although sessile organisms, which show limited or no movement, need sperm with a capacity to swim for long distances to find the oocytes, swimmer organisms can move toward the female and release gametes near it, and therefore the spermatozoa does not need to swim for such a long time. At the same time, sperm morphology is related to sperm motion parameters, and in this study an in-depth morphometric analysis of ascidian, sea urchin, and pufferfish spermatozoa, using computer-assisted sperm analysis software, has been carried out for the first time. A huge variability in shapes, sizes, and structures of the studied species was found using electron microscopy.

  4. Tunicate mitogenomics and phylogenetics: peculiarities of the Herdmania momus mitochondrial genome and support for the new chordate phylogeny

    PubMed Central

    2009-01-01

    Background Tunicates represent a key metazoan group as the sister-group of vertebrates within chordates. The six complete mitochondrial genomes available so far for tunicates have revealed distinctive features. Extensive gene rearrangements and particularly high evolutionary rates have been evidenced with regard to other chordates. This peculiar evolutionary dynamics has hampered the reconstruction of tunicate phylogenetic relationships within chordates based on mitogenomic data. Results In order to further understand the atypical evolutionary dynamics of the mitochondrial genome of tunicates, we determined the complete sequence of the solitary ascidian Herdmania momus. This genome from a stolidobranch ascidian presents the typical tunicate gene content with 13 protein-coding genes, 2 rRNAs and 24 tRNAs which are all encoded on the same strand. However, it also presents a novel gene arrangement, highlighting the extreme plasticity of gene order observed in tunicate mitochondrial genomes. Probabilistic phylogenetic inferences were conducted on the concatenation of the 13 mitochondrial protein-coding genes from representatives of major metazoan phyla. We show that whereas standard homogeneous amino acid models support an artefactual sister position of tunicates relative to all other bilaterians, the CAT and CAT+BP site- and time-heterogeneous mixture models place tunicates as the sister-group of vertebrates within monophyletic chordates. Moreover, the reference phylogeny indicates that tunicate mitochondrial genomes have experienced a drastic acceleration in their evolutionary rate that equally affects protein-coding and ribosomal-RNA genes. Conclusion This is the first mitogenomic study supporting the new chordate phylogeny revealed by recent phylogenomic analyses. It illustrates the beneficial effects of an increased taxon sampling coupled with the use of more realistic amino acid substitution models for the reconstruction of animal phylogeny. PMID:19922605

  5. Calcium at fertilization and in early development

    PubMed Central

    Whitaker, Michael

    2012-01-01

    Fertilization calcium waves are introduced and the evidence from which we can infer general mechanisms of these waves is presented. The two main classes of hypothesis put forward to explain the generation of the fertilization calcium wave are set out and it is concluded that initiation of the fertilization calcium wave can be most generally explained in inverterbrates by a mechanism in which an activating substance enters the egg from the sperm on sperm-egg fusion, activating the egg by stimulating phospholipase C activation through a src family kinase pathway and in mammals by the diffusion of a sperm-specific phospholipase C from sperm to egg on sperm-egg fusion. The fertilization calcium wave is then set into the context of cell cycle control and the mechanism of repetitive calcium spiking in mammalian eggs is investigated. Evidence that calcium signals control cell division in early embryos is reviewed, and it is concluded that calcium signals are essential at all three stages of cell division in early embryos. Evidence that phosphoinositide signalling pathways control the resumption of meiosis during oocyte maturation is considered. It is concluded on balance that the evidence points to a need for phosphoinositide/calcium signalling during resumption of meiosis. Changes to the calcium signalling machinery occur during meiosis to enable the production of a calcium wave in the mature oocyte when it is fertilized; evidence that the shape and structure of the endoplasmic reticulum alters dynamically during maturation and after fertilization is reviewed and the link between ER dynamics and the cytoskeleton is discussed. There is evidence that calcium signalling plays a key part in the development of patterning in early embryos. Morphogenesis in ascidian, frog and zebrafish embryos is briefly described to provide the developmental context in which calcium signals act. Intracellular calcium waves that may play a role in axis formation in ascidian are discussed

  6. The Ciona intestinalis genome: when the constraints are off

    NASA Technical Reports Server (NTRS)

    Holland, Linda Z.; Gibson-Brown, Jeremy J.

    2003-01-01

    The recent genome sequencing of a non-vertebrate deuterostome, the ascidian tunicate Ciona intestinalis, makes a substantial contribution to the fields of evolutionary and developmental biology.1 Tunicates have some of the smallest bilaterian genomes, embryos with relatively few cells, fixed lineages and early determination of cell fates. Initial analyses of the C. intestinalis genome indicate that it has been evolving rapidly. Comparisons with other bilaterians show that C. intestinalis has lost a number of genes, and that many genes linked together in most other bilaterians have become uncoupled. In addition, a number of independent, lineage-specific gene duplications have been detected. These new results, although interesting in themselves, will take on a deeper significance once the genomes of additional invertebrate deuterostomes (e.g. echinoderms, hemichordates and amphioxus) have been sequenced. With such a broadened database, comparative genomics can begin to ask pointed questions about the relationship between the evolution of genomes and the evolution of body plans. Copyright 2003 Wiley Periodicals, Inc.

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

    PubMed Central

    Kuete, Victor; Biavatti, Maique W

    2015-01-01

    Summary 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. PMID:26664587

  8. Diverse ETS transcription factors mediate FGF signaling in the Ciona anterior neural plate.

    PubMed

    Gainous, T Blair; Wagner, Eileen; Levine, Michael

    2015-03-15

    The ascidian Ciona intestinalis is a marine invertebrate belonging to the sister group of the vertebrates, the tunicates. Its compact genome and simple, experimentally tractable embryos make Ciona well-suited for the study of cell-fate specification in chordates. Tunicate larvae possess a characteristic chordate body plan, and many developmental pathways are conserved between tunicates and vertebrates. Previous studies have shown that FGF signals are essential for neural induction and patterning at sequential steps of Ciona embryogenesis. Here we show that two different ETS family transcription factors, Ets1/2 and Elk1/3/4, have partially redundant activities in the anterior neural plate of gastrulating embryos. Whereas Ets1/2 promotes pigment cell formation in lateral lineages, both Ets1/2 and Elk1/3/4 are involved in the activation of Myt1L in medial lineages and the restriction of Six3/6 expression to the anterior-most regions of the neural tube. We also provide evidence that photoreceptor cells arise from posterior regions of the presumptive sensory vesicle, and do not depend on FGF signaling. Cells previously identified as photoreceptor progenitors instead form ependymal cells and neurons of the larval brain. Our results extend recent findings on FGF-dependent patterning of anterior-posterior compartments in the Ciona central nervous system.

  9. Repression of Rx gene on the left side of the sensory vesicle by Nodal signaling is crucial for right-sided formation of the ocellus photoreceptor in the development of Ciona intestinalis.

    PubMed

    Yoshida, Keita; Saiga, Hidetoshi

    2011-06-01

    Nodal signaling plays an essential role in the establishment of left-right asymmetry in various animals. However, it is largely unknown how Nodal signaling is involved in the establishment of the left-right asymmetric morphology. In this study, the role of Nodal signaling in the left-right asymmetric ocellus formation in the ascidian, Ciona intestinalis was dealt with. During the development of C. intestinalis, the ocellus pigment cell forms on the midline and moves to the right side of the midline. Then, the photoreceptor cells form on the right side of the sensory vesicle (SV). Ci-Nodal is expressed on the left side of the SV in the developing tail bud embryo. When Nodal signaling is inhibited, the ocellus pigment cell form but remain on the midline, and expression of marker genes of the ocellus photoreceptor cells is ectopically detected on the left side as well as on the right side of the SV in the larva. Furthermore, Ci-Rx, which is essential for the ocellus differentiation, turns out to be negatively regulated by the Nodal signaling on the left side of the SV, even though it is required for the right-sided photoreceptor formation. These results indicate that Nodal signaling controls the left-right asymmetric ocellus formation in the development of C. intestinalis.

  10. The expression of an immune-related phenoloxidase gene is modulated in Ciona intestinalis ovary, test cells, embryos and larva.

    PubMed

    Parrinello, Daniela; Sanfratello, Maria A; Vizzini, Aiti; Cammarata, Matteo

    2015-03-01

    Two distinct Ciona intestinalis phenoloxidases (CinPO1, 2) had previously been cloned and sequenced. The CinPO2 is involved in innate immunity and is expressed by inflammatory hemocytes that populate the tunic and pharynx vessels as a response to LPS inoculation. In situ hybridization and immunohistochemistry assays on histological section, showed that the expression of this gene and the produced protein are shared with oogenesis, embryogenesis and larval morphogenesis. Intriguingly, upregulation of gene transcription was found in the test cell layer that envelopes the ovary follicle, ovulated egg, and gastrula, as well as it was modulated in the zygotic nucleus of outer balstomers of 32-cell embryo, neurula presumptive epidermis tissue and larval mesenchyme. The anti-CinPO2 antibodies, specific for adult inflammatory cells, recognize epitopes in the cytoplasm of ovarian oocytes, ovulated eggs, development stages and larval mesenchyme. The overall findings disclose the precocious activation of the CinPO2 immunity-related gene, and show a developmentally programmed expression of this phenoloxidase. Furthermore, these findings support the multifunctional roles of immunity-related genes and allows us to explore new perspectives on ascidian development and immunity.

  11. Identification of autophagy genes in Ciona intestinalis: a new experimental model to study autophagy mechanism.

    PubMed

    Godefroy, Nelly; Hoa, Céline; Tsokanos, Foivos; Le Goff, Emilie; Douzery, Emmanuel J P; Baghdiguian, Stephen; Martinand-Mari, Camille

    2009-08-01

    Programmed cell death (PCD) is a mechanism implicated in many physiological and pathological processes. Until recently, apoptosis (self-killing) was the most largely studied mechanism of PCD but a growing number of laboratories are now interested in autophagy (self-eating). In the past few years data showing a tight link between both pathways has accumulated. Until now our laboratory used Ciona intestinalis, a chordate model in which in vivo experiments are possible, to study apoptosis. Recently, we showed that autophagy also occurs in the development of Ciona intestinalis and that the specific markers of both types of death are found in the same tissues and/or in the same cells. These results drove us to postulate that Ciona intestinalis can be a good model to study the link between apoptosis and autophagy. In this article, we conducted an in silico study of autophagy genes. We explored the genomes of Ciona intestinalis, of the second ascidian Ciona savignyi, and those of the classical biological models (Saccharomyces cerevisiae, Drosophila melanogaster, Caenorhabditis elegans and Homo sapiens) to extract and compare autophagy gene sequences. This genomic study was completed by an analysis of: (i) mRNA profile expression during development and (ii) the localization of Beclin protein by immunofluorescent staining in the Ciona intestinalis larvae. Taken together, the results allowed us to conclude that a complex autophagic machinery is present in Ciona intestinalis. Actually, the number of autophagy genes in Ciona intestinalis is comparable to the number of autophagy genes in human.

  12. Functional studies of the Ciona intestinalis myogenic regulatory factor reveal conserved features of chordate myogenesis.

    PubMed

    Izzi, Stephanie A; Colantuono, Bonnie J; Sullivan, Kelly; Khare, Parul; Meedel, Thomas H

    2013-04-15

    Ci-MRF is the sole myogenic regulatory factor (MRF) of the ascidian Ciona intestinalis, an invertebrate chordate. In order to investigate its properties we developed a simple in vivo assay based on misexpressing Ci-MRF in the notochord of Ciona embryos. We used this assay to examine the roles of three structural motifs that are conserved among MRFs: an alanine-threonine (Ala-Thr) dipeptide of the basic domain that is known in vertebrates as the myogenic code, a cysteine/histidine-rich (C/H) domain found just N-terminal to the basic domain, and a carboxy-terminal amphipathic α-helix referred to as Helix III. We show that the Ala-Thr dipeptide is necessary for normal Ci-MRF function, and that while eliminating the C/H domain or Helix III individually has no demonstrable effect on Ci-MRF, simultaneous loss of both motifs significantly reduces its activity. Our studies also indicate that direct interaction between CiMRF and an essential E-box of Ciona Troponin I is required for the expression of this muscle-specific gene and that multiple classes of MRF-regulated genes exist in Ciona. These findings are consistent with substantial conservation of MRF-directed myogenesis in chordates and demonstrate for the first time that the Ala/Thr dipeptide of the basic domain of an invertebrate MRF behaves as a myogenic code.

  13. 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.

    PubMed

    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.

  14. Ciona intestinalis peroxinectin is a novel component of the peroxidase-cyclooxygenase gene superfamily upregulated by LPS.

    PubMed

    Vizzini, Aiti; Parrinello, Daniela; Sanfratello, Maria Antonietta; Mangano, Valentina; Parrinello, Nicolò; Cammarata, Matteo

    2013-09-01

    Peroxinectins function as hemoperoxidase and cell adhesion factor involved in invertebrate immune reaction. In this study, the ascidian (Ciona intestinalis) peroxinectin gene (CiPxt) and its expression during the inflammatory response have been examined. CiPxt is a new member of the peroxidase-cyclooxygenase gene superfamily that contains both the peroxidase domain and the integrin KGD (Lys-Gly-Asp) binding motif. A phylogenetic tree showed that CiPxt is very close to the chordate group and appears to be the outgroup of mammalian MPO, EPO and TPO clades. The CiPxt molecular structure model resulted superimposable to the human myeloperoxidase. The CiPxt mRNA expression is upregulated by LPS inoculation suggesting it is involved in C. intestinalis inflammatory response. The CiPxt was expressed in hemocytes (compartment/morula cells), vessel epithelium, and unilocular refractile granulocytes populating the inflamed tunic matrix and in the zones 7, 8 and 9 of the endostyle, a special pharynx organs homolog to the vertebrate thyroid gland.

  15. Cadmium effects in food chain experiments with marine plankton algae (dinophyta) and benthic filter feeders(Tunicata)

    NASA Astrophysics Data System (ADS)

    Kayser, H.

    The dinoflagellate Scrippsiella faeroense was grown in continuous flow-through cultures (10 1 turbidostat), the outflow leading into vessels containing tunicates of the species Ciona intestinalis, Ascidiella aspersa, Molgula manhattensi and Botryllus schlosseri. The culture medium consisted of natural sea water enriched only with N and P components. CdCl 2 was added to the system at sublethal concentrations. Algal growth wass affected at a Cd ++ concentration of 10 μg·1 -1; sublethal toxicity thresholds of the tunicates ranged from 5 to 10 μg·1 -1. Cadmium accumulation was much higer in the algae than in the tunicates; in spite of the continuous supply of relatively highly Cd contaminated algae, the Cd content of algae-fed tunicates increased insignificantly by comparison with unfed specimens. Only a small percentage of the Cd offered via the food algae was actually assimilated by the ascidians during the first 3 weeks of the experiment. Cd content of the tunicates remained almost constant for the next 2 weeks of the experiment, indicating that ingestion and excretion of the metal was at equilibrium. The concentration factor of Cd decreased through the trophic chain.

  16. Three-dimensional anatomy of the Ciona intestinalis tailbud embryo at single-cell resolution.

    PubMed

    Nakamura, Mitsuru J; Terai, Jun; Okubo, Reiko; Hotta, Kohji; Oka, Kotaro

    2012-12-15

    During embryogenesis, chordates pass through a tailbud stage in which the larval tail is formed. Since acquisition of a tadpole-like tail during tailbud stage is one of the key events in the evolution of chordates, understanding the anatomy of the tailbud stage chordate embryo is of special interest. In this study, to understand comprehensively the anatomy of the tailbud embryo at single-cell-level, real microscopic image stacks of the tailbud embryo in Ciona intestinalis were reconstructed into a 3D computer model. This comprehensive 3D model of the ascidian tailbud embryo was based on real images of confocal laser scanning microscope (CLSM) and therefore, cell shape, location and cell arrangement reflect real geometries of the tailbud embryo. We found that the tailbud embryo consists of 1579 cells, including 836 epidermal cells, 228 cells in the central nervous system, 218 mesenchymal cells, four trunk ventral cells, two B/B(⁎)8.11 cells, 36 muscle cells, 40 notochord cells, four primordial germ cells, and 199 endodermal cells. Moreover, we identified for the first time two populations of previously undefined cells (a total of 12 cells) in Ciona: one located in the lateral trunk and the other located under the tail dorsal epidermis. This information provides a first step for understanding how the body plan of the chordate tailbud embryo formed and evolved.

  17. A transiently expressed connexin is essential for anterior neural plate development in Ciona intestinalis.

    PubMed

    Hackley, Christopher; Mulholland, Erin; Kim, Gil Jung; Newman-Smith, Erin; Smith, William C

    2013-01-01

    A forward genetic screen in the ascidian Ciona intestinalis identified a mutant line (frimousse) with a profound disruption in neural plate development. In embryos with the frimousse mutation, the anteriormost neural plate cells, which are products of an FGF induction at the blastula and gastrula stages, initially express neural plate-specific genes but fail to maintain the induced state and ultimately default to epidermis. The genetic lesion in the frimousse mutant lies within a connexin gene (cx-11) that is transiently expressed in the developing neural plate in a temporal window corresponding to the period of a-lineage neural induction. Using a genetically encoded calcium indicator we observed multiple calcium transients throughout the developing neural plate in wild-type embryos, but not in mutant embryos. A series of treatments at the gastrula and neurula stages that block the calcium transients, including gap junction inhibition and calcium depletion, were also found to disrupt the development of the anterior neural plate in a similar way to the frimousse mutation. The requirement for cx-11 for anterior neural fate points to a crucial role for intercellular communication via gap junctions, probably through mediation of Ca(2+) transients, in Ciona intestinalis neural induction.

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

    PubMed

    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.

  19. External amebocytes guard the pharynx entry in a tunicate (Ascidiacea).

    PubMed

    Cima, Francesca; Ballarin, Loriano; Gasparini, Fabio; Burighel, Paolo

    2006-01-01

    In the present report, we describe the identification of unusual free amebocytes, completely exposed to seawater, which inhabit the inner surface of the oral and atrial siphons of the compound ascidian Botryllus schlosseri (Urochordata). The origin and biological role of these cells were studied by cytochemical and ultrastructural analysis. These amebocytes are mononucleate cells, with numerous round granules, varying in content, and long filopodia, which contact the cuticle protrusions of the tunic in the siphon. Histochemical, histoenzymatic and immunohistochemical assays were carried out under light microscopy on sections and on living and fixed cultured hemocytes. Results showed that the phagocytic blood cells and the free amebocytes of the siphons shared: (i) affinity for the alpha-mannose specific agglutinin of Narcissus pseudonarcissus (NPA), (ii) occurrence of hydrolytic activities of acid phosphatase and non-specific esterases inside lysosomal vesicles and large vacuoles, (iii) membrane labeling with the lipophilic dye PKH26 specific for phagocytic cells, (iv) anti-CD39 immunocytochemical labeling specific for lysosomes of mammalian macrophages. All histochemical data support the hypothesis that these cells are 'sentinel cells' belonging to the hyaline amebocyte population of the phagocytic differentiation line of the immunocytes, since they can also recognize and phagocytize carmine experimentally administered as target particles.

  20. Preliminary characterization of complement in a colonial tunicate: C3, Bf and inhibition of C3 opsonic activity by compstatin.

    PubMed

    Franchi, Nicola; Ballarin, Loriano

    2014-10-01

    The complement system is a fundamental effector mechanism of the innate immunity in both vertebrates and invertebrates. The comprehension of its roots in the evolution is a useful step to understand how the main complement-related proteins had changed in order to adapt to new environmental conditions and life-cycles or, in the case of vertebrates, to interact with the adaptive immunity. Data on organisms evolutionary close to vertebrates, such as tunicates, are of primary importance for a better understanding of the changes in immune responses associated with the invertebrate-vertebrate transition. Here we report on the characterization of C3 and Bf transcripts from the colonial ascidian Botryllus schlosseri (BsC3 and BsBf, respectively), a reliable model organism for immunobiological research, and present a comparative analysis of amino acid sequences of C3s and Bfs suggesting that, in deuterostomes, the structure of these proteins remained largely unchanged. We also present new data on the cells responsible of the expression of BsC3 and BsBf showing that cytotoxic immunocytes are the sole cells where the relative transcripts can be found. Finally, using the C3 specific inhibitor compstatin, we demonstrate the opsonic role of BsC3 in accordance with the idea that promotion of phagocytosis is one of the main function of C3 in metazoans.

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

    PubMed

    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).

  2. Erosion of phylogenetic signal in tunicate mitochondrial genomes on different levels of analysis.

    PubMed

    Stach, Thomas; Braband, Anke; Podsiadlowski, Lars

    2010-06-01

    The molecular phylogenetic position of Tunicata and internal interrelationship of higher tunicate taxa is controversial. High substitution rates and extreme gene order variability hamper phylogenetic analyses. We describe the sequence and organization of the mitochondrial genome of the aplousobranch ascidian Clavelina lepadiformis and use mitochondrial genomes to investigate phylogenetic information content on different molecular levels of comparison. Despite agreement in phylogenetic analyses of nucleotide and amino acid sequences, split analyses revealed little phylogenetic signal. Split analyses on molecular data sets deemed increasingly conservative, demonstrated that the lack of signal pervades all levels and that it is Tunicata the taxon of interest that introduces noise in the data sets. The strongest signal present in our molecular data sets as revealed by split analyses is not present in the optimal cladograms and supports a sister group relationship between cephalochordates and craniates. Phylogenetic analysis of gene order using common interval algorithms shows that phylogenetic signal is also eroded in respect of gene positions. Even functional constraints, such as partial gene overlap as exemplified in the case of the commonly observed adjacency between cox2 and cytb are subjected to homoplasy. However, rare phylogenetic events like this hold some promise to retain phylogenetic information even in such cases of extreme variability. We therefore caution to rely on sequence analysis alone and recommend investigation into the signal content of molecular data sets in order to assess the strength of phylogenetic signal.

  3. Identification of immune-relevant genes in histoincompatible rejecting colonies of the tunicate Botryllus schlosseri.

    PubMed

    Oren, Matan; Douek, Jacob; Fishelson, Zvi; Rinkevich, Baruch

    2007-01-01

    The colonial ascidian Botryllus schlosseri manifests a unique allorecognition system that is controlled by a single histocompatibility haplotype, the Fu/HC locus. When two allogeneic incompatible colonies come into direct contact, they develop inflammatory-like rejection lesions, called points of rejection (POR). While screening for differentially expressed genes during POR formation, we developed and analyzed a cDNA library of expressed sequence tags (ESTs) with 1693 unique ESTs that were clustered and assembled into 217 contigs and 1476 singlets. About 51% of these ESTs showed high similarity (E-value 0.005) to known database sequences, of which 123 matches were identified as immune-relevant genes encoding for stress proteins, pattern recognition receptors and complement proteins, proteases and protease inhibitors, cell adhesion and coagulation proteins, cytokine-related proteins, programmed cell death and proteasome-associated proteins. This first EST wide-screening analysis of the Botryllus allorecognition effector arm reveals a complex innate immune system, hallmarked by a whole genome response to allorecognition challenge.

  4. More diversity and more convergence in tunicate biology.

    PubMed

    Nishida, Hiroki; Satoh, Nori; Hirose, Euichi

    2010-02-01

    The 5th International Tunicate Meeting (ITM5) was held at the Okinawa Industry Support Center (Naha, Okinawa, Japan) from June 21 to 25, 2009, with support from the Okinawa Institute of Science and Technology (OIST) and the Inoue Foundation for Science. Tunicates are defined as deuterostome metazoans that have notochord in the tail at one point or at all times during their life. Presence of a cellulosic integument is also a synapomorphy for this taxon, which consists of three classes: Ascidiacea, Thaliacea, and Appendicularia. Ascidians, the largest class, are always sessile, while thaliaceans and appendicularians are pelagic throughout their life. Many unique and interesting data sets are available that facilitate research on tunicates, such as full-genome information for Ciona, numerous ESTs with in-situ hybridization images, well-documented cell lineages during embryogenesis, among many others. The present note gives an overview of the topics from the sessions and plenary lectures of ITM5. As seen below, the tunicate scientific community is worldwide, with flexible networks among tunicate biologists, and a particularly wide range of species diversity and phenomena were presented during ITM5. ITM6 is planned for 2011 in Montreal.

  5. Excision and transposition activity of Tc1/mariner superfamily transposons in sea urchin embryos.

    PubMed

    Sasakura, Yasunori; Yaguchi, Junko; Yaguchi, Shunsuke; Yajima, Mamiko

    2010-03-01

    Tc1/mariner superfamily transposons are used as transformation vectors in various model organisms. The utility of this transposon family is evidenced by the fact that Tc1/mariner transposons have loose host specificity. However, the activity of these transposons has been observed in only a few organisms, and a recent study in the ascidian Ciona intestinalis suggests that not all Tc1/ mariner transposons show loose host specificity. To understand host specificity, we used sea urchins, since they have a long history as materials of embryology and developmental biology. Transposon techniques have not been reported in this organism, despite the likelihood that these techniques would open up many experimental possibilities. Here we tested the activity of three Tc1/ mariner transposons (Minos, Sleeping Beauty, and Frog Prince) in the sea urchin Hemicentrotus pulcherrimus. Minos has both excision and transposition activity in H. pulcherrimus embryos, whereas no excision activity was detected for Sleeping Beauty or Frog Prince. This study suggests that Minos is active in a broad range of non-host organisms and can be used as a transformation tool in sea urchin embryos.

  6. The distribution of dimethylsulfoniopropionate in tropical Pacific coral reef invertebrates

    NASA Astrophysics Data System (ADS)

    van Alstyne, Kathryn L.; Schupp, Peter; Slattery, Marc

    2006-08-01

    Dimethylsulfoniopropionate (DMSP) is an important component of the global sulfur cycle and may be involved, via its cleavage product dimethylsulfide, in climate regulation. Although it is common in many algae, reports of DMSP in animals, particularly tropical invertebrates, are limited. This study examined the distribution of DMSP in a diverse group of coral reef invertebrates. DMSP was present in all 22 species of cnidarians and ranged from 9 to 723 μmol g-1 of dry mass (DM) with a mean (± 1SD) of 110 ± 180 μmol g-1 DM. It was not detected in a flatworm and an ascidian or in two of five sponges. Concentrations in sponges ranged from undetectable to 16 μmol g-1 DM with a mean of 4 ± 7 μmol g-1 DM. Within the cnidarians, DMSP concentrations did not differ among orders. Among cnidarian species, DMSP concentrations were correlated with symbiotic zooxanthellae densities. Within cnidarian species, DMSP concentrations of individuals were positively correlated with zooxanthellae densities in three of the four species examined. We speculate that DMSP is dietarily derived in sponges and derived from zooxanthellae in the cnidarians. The functions of DMSP in coral reef invertebrates are not known.

  7. Efficient utilization of very dilute aquatic sperm: sperm competition may be more likely than sperm limitation when eggs are retained.

    PubMed Central

    Pemberton, Andrew J; Hughes, Roger N; Manríquez, Patricio H; Bishop, John D D

    2003-01-01

    Fertilization success may be severely limited in marine invertebrates that spawn both male and female gametes. In a diverse group of aquatic organisms only sperm are released, with sperm-egg fusion occurring at the mother. Here, we report fertilization kinetics data for two such 'brooding' or 'spermcast' species--representing each major clade of the animal kingdom. High levels of fertilization were achieved at sperm concentrations of two or three orders of magnitude lower than is common with broadcast spawning species. At a concentration of 100 sperm ml(-1), fertilization rates of a bryozoan and colonial ascidian were near maximum, whereas most broadcast spawners would have displayed near complete reproductive failure. A further experiment looked at the rate of uptake of sperm under natural conditions. Results suggested that sperm released at ca. 0.9 m from an acting female could be collected at a rate of 3-12 times greater than the minimum required simply to avoid sperm limitation. Thus, evolutionary pressures on gametic and other reproductive characteristics of many species that release sperm but retain eggs may be quite different from those of broadcast spawners and may confer on the former an enhanced scope for sperm competition and female choice. PMID:14667389

  8. Biomechanics and energy cost of the amphipod Corophium volutator filter-pump.

    PubMed

    Riisgård, Hans Ulrik

    2007-04-01

    The integrated function of the setal filter-basket and the pleopodal pump in the burrowing amphipod Corophium volutator was studied by video-microscopy in order to evaluate the energy costs of filter feeding. Video-microscope observations indicated that, in general, nine short, water-pumping beat cycles of the pleopods are succeeded by one slow cycle that coincides with cleaning of the setal filter and transient slowdown of inhalant water velocity. The position of the plumose setal filter on the second pair of gnathopods ensures that all water runs through the filter-basket. The fine V-shaped bristles on the setae enlarge the total filter area so that the velocity of water flowing through the filter is relatively slow, about 2.5 mm s(-1), giving rise to a resistance of about 2.9 mm H(2)O, which is the most important contribution to the total pressure drop in the system. In "standard" individuals of C. volutator with lengths of 3 and 6 mm, the normal operating pump pressure and pumping rate were, respectively, 2.6 and 3.1 mm H(2)O, and 18.3 and 85.5 ml h(-1); the overall pump efficiencies were 5.1% and 11.6%, respectively. These results show that the Corophium filter-pump is comparable to other low-pressure biological pumps in filter-feeding marine invertebrates, such as mussels, polychaetes, ascidians, and bryozoans.

  9. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    PubMed

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP.

  10. Marine biofouling on fish farms and its remediation.

    PubMed

    Braithwaite, R A; McEvoy, L A

    2005-01-01

    The fish farming industry suffers significantly from the effects of biofouling. The fouling of cages and netting, which is costly to remove, is detrimental to fish health and yield and can cause equipment failure. With rapid expansion of the aquaculture industry, coupled with the tightening of legislation on the use of antifouling biocides, the problems of fish farm biofouling are increasing. The nature of the biological communities that develop on fish farm equipment and the antifouling practices that can be employed to reduce it are described here. Particular emphasis is placed on antifouling legislature and the future needs of the industry. The biological communities that develop on fish cages and netting are distinctive, in comparison to those that foul ships. Temperate species of particular importance, because of their cosmopolitan distribution and opportunistic nature, include the blue mussel Mytilus edulis and the ascidian Ciona intestinalis. Antifouling practices include predominantly the use of copper-based antifoulant coatings, in combination with practical fish husbandry and site management practices. The antifouling solutions presently available are not ideal, and it is widely accepted that there is an urgent need for research into combatant technologies. Such alternatives include the adoption of "foul-release" technologies and "biological control" through the use of polyculture systems. However, none of these have, as yet, been proven satisfactory. In view of current legislative trends and the possible future "phasing out" of available antifouling materials, there is a need to find alternative strategies.

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

    PubMed

    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.

  12. Biosynthetic origin of natural products isolated from marine microorganism-invertebrate assemblages.

    PubMed

    Simmons, T Luke; Coates, R Cameron; Clark, Benjamin R; Engene, Niclas; Gonzalez, David; Esquenazi, Eduardo; Dorrestein, Pieter C; Gerwick, William H

    2008-03-25

    In all probability, natural selection began as ancient marine microorganisms were required to compete for limited resources. These pressures resulted in the evolution of diverse genetically encoded small molecules with a variety of ecological and metabolic roles. Remarkably, many of these same biologically active molecules have potential utility in modern medicine and biomedical research. The most promising of these natural products often derive from organisms richly populated by associated microorganisms (e.g., marine sponges and ascidians), and often there is great uncertainty about which organism in these assemblages is making these intriguing metabolites. To use the molecular machinery responsible for the biosynthesis of potential drug-lead natural products, new tools must be applied to delineate their genetic and enzymatic origins. The aim of this perspective is to highlight both traditional and emerging techniques for the localization of metabolic pathways within complex marine environments. Examples are given from the literature as well as recent proof-of-concept experiments from the authors' laboratories.

  13. Ammonium channel expression is essential for brain development and function in the larva of Ciona intestinalis.

    PubMed

    Marino, Rita; Melillo, Daniela; Di Filippo, Miriam; Yamada, Atsuko; Pinto, Maria Rosaria; De Santis, Rosaria; Brown, Euan R; Matassi, Giorgio

    2007-07-01

    Ammonium uptake into the cell is known to be mediated by ammonium transport (Amt) proteins, which are present in all domains of life. The physiological role of Amt proteins remains elusive; indeed, loss-of-function experiments suggested that Amt proteins do not play an essential role in bacteria, yeast, and plants. Here we show that the reverse holds true in the tunicate Ciona intestinalis. The genome of C. intestinalis contains two AMT genes, Ci-AMT1a and Ci-AMT1b, which we show derive from an ascidian-specific gene duplication. We analyzed Ci-AMT expression during embryo development. Notably, Ci-AMT1a is expressed in the larval brain in a small number of cells defining a previously unseen V-shaped territory; these cells connect the brain cavity to the external environment. We show that the knockdown of Ci-AMT1a impairs the formation of the brain cavity and consequently the function of the otolith, the gravity-sensing organ contained in it. We speculate that the normal mechanical functioning (flotation and free movement) of the otolith may require a close regulation of ammonium salt(s) concentration in the brain cavity, because ammonium is known to affect both fluid density and viscosity; the cells forming the V territory may act as a conduit in achieving such a regulation.

  14. Two new species of diplosoma (Ascidiacea: Didemnidae) bearing prokaryotic algae prochloron from Okinawajima (Ryukyu Archipelago, Japan).

    PubMed

    Oka, Atsushi T; Suetsugu, Mayu; Hirose, Euichi

    2005-03-01

    Two new species of didemnid ascidians, Diplosoma ooru sp. nov. and Diplosoma simileguwa sp. nov., are described from coral reefs on Okinawajima (Ryukyu Archipelago, Japan). These two species form green colonies, having a symbiotic association with a prokaryotic alga Prochloron sp. The former species was found at the reef edges in the subtidal zone and the latter was found in a shallow reef lagoon. In these species, the colonies are thinner and the zooids are smaller than those of any other Prochloron-bearing Diplosoma species so far described. Moreover, each of the present new species has a unique combination of stigmatic numbers: 5 stigmata in the first and third rows, 6 in the second row, and 4 in the fourth in D. ooru; 4 stigmata in the first and third rows, 5 in the second row, and 3 in the fourth in D. simileguwa. In both of the new species, the retractor muscle emerges from the underside of the thorax. Larval morphology of D. ooru is also described.

  15. Mutual modulation between norepinephrine and nitric oxide in haemocytes during the mollusc immune response.

    PubMed

    Jiang, Qiufen; Zhou, Zhi; Wang, Lingling; Yang, Chuanyan; Wang, Jingjing; Wu, Tiantian; Song, Linsheng

    2014-11-07

    Nitric oxide (NO) is one of the most important immune molecules in innate immunity of invertebrates, and it can be regulated by norepinephrine in ascidian haemocytes. In the present study, the mutual modulation and underlying mechanism between norepinephrine and NO were explored in haemocytes of the scallop Chlamys farreri. After lipopolysaccharide stimulation, NO production increased to a significant level at 24 h, and norepinephrine concentration rose to remarkable levels at 3 h and 12~48 h. A significant decrease of NO production was observed in the haemocytes concomitantly stimulated with lipopolysaccharide and α-adrenoceptor agonist, while a dramatic increase of NO production was observed in the haemocytes incubated with lipopolysaccharide and β-adrenoceptor agonist. Meanwhile, the concentration of cyclic adenosine monophosphate (cAMP) decreased significantly in the haemocytes treated by lipopolysaccharide and α/β-adrenoceptor agonist, while the content of Ca(2+) was elevated in those triggered by lipopolysaccharide and β-adrenoceptor agonist. When the haemocytes was incubated with NO donor, norepinephrine concentration was significantly enhanced during 1~24 h. Collectively, these results suggested that norepinephrine exerted varied effects on NO production at different immune stages via a novel α/β-adrenoceptor-cAMP/Ca(2+) regulatory pattern, and NO might have a feedback effect on the synthesis of norepinephrine in the scallop haemocytes.

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

    PubMed Central

    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

  17. Ephrin-mediated restriction of ERK1/2 activity delimits the number of pigment cells in the Ciona CNS

    PubMed Central

    Haupaix, Nicolas; Abitua, Philip B.; Sirour, Cathy; Yasuo, Hitoyoshi; Levine, Michael; Hudson, Clare

    2014-01-01

    Recent evidence suggests that ascidian pigment cells are related to neural crest-derived melanocytes of vertebrates. Using live-imaging, we determine a revised cell lineage of the pigment cells in Ciona intestinalis embryos. The neural precursors undergo successive rounds of anterior-posterior (A-P) oriented cell divisions, starting at the blastula 64-cell stage. A previously unrecognized fourth A-P oriented cell division in the pigment cell lineage leads to the generation of the post-mitotic pigment cell precursors. We provide evidence that MEK/ERK signals are required for pigment cell specification until approximately 30 minutes after the final cell division has taken place. Following each of the four A-P oriented cell divisions, ERK1/2 is differentially activated in the posterior sister cells, into which the pigment cell lineage segregates. Eph/ephrin signals are critical during the third A-P oriented cell division to spatially restrict ERK1/2 activation to the posterior daughter cell. Targeted inhibition of Eph/ephrin signals results in, at neurula stages, anterior expansion of both ERK1/2 activation and a pigment cell lineage marker and subsequently, at larval stages, supernumerary pigment cells. We discuss the implications of these findings with respect to the evolution of the vertebrate neural crest. PMID:25062608

  18. Wnt signaling balances specification of the cardiac and pharyngeal muscle fields.

    PubMed

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

    2017-02-01

    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.

  19. Global diversity of Ascidiacea.

    PubMed

    Shenkar, Noa; Swalla, Billie J

    2011-01-01

    The class Ascidiacea presents fundamental opportunities for research in the fields of development, evolution, ecology, natural products and more. This review provides a comprehensive overview of the current knowledge regarding the global biodiversity of the class Ascidiacea, focusing in their taxonomy, main regions of biodiversity, and distribution patterns. Based on analysis of the literature and the species registered in the online World Register of Marine Species, we assembled a list of 2815 described species. The highest number of species and families is found in the order Aplousobranchia. Didemnidae and Styelidae families have the highest number of species with more than 500 within each group. Sixty percent of described species are colonial. Species richness is highest in tropical regions, where colonial species predominate. In higher latitudes solitary species gradually contribute more to the total species richness. We emphasize the strong association between species richness and sampling efforts, and discuss the risks of invasive species. Our inventory is certainly incomplete as the ascidian fauna in many areas around the world is relatively poorly known, and many new species continue to be discovered and described each year.

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

    PubMed Central

    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

  1. Experimental removal and recovery of subtidal grazers highlights the importance of functional redundancy and temporal context.

    PubMed

    Elahi, Robin; Sebens, Kenneth P

    2013-01-01

    The extent to which different grazers are functionally redundant has strong implications for the maintenance of community structure and function. Grazing by red urchins (Strongylocentrotus franciscanus) on temperate rocky reefs can initiate a switch from invertebrate or macroalgal dominance to an algal crust state, but can also cause increases in the density of molluscan mesograzers. In this study, we tested the hypothesis that red urchins and lined chitons (Tonicella spp.) are redundant in the maintenance of available space, defined as encrusting algae and bare rock. In a factorial field experiment replicated at three sites, we reduced the densities of urchins and chitons on subtidal rock walls for nine months. The effects of grazers were interpreted in the context of natural temporal variation by monitoring the benthic community one year before, during, and after grazer removal. The removal of each grazer in isolation had no effect on the epilithic community, but the removal of both grazers caused an increase in sessile invertebrates. The increase was due primarily to clonal ascidians, which displayed a large (∼75%) relative increase in response to the removal of both grazers. However, the observed non-additive responses to grazer removal were temporary and smaller than seasonal fluctuations. Our data demonstrate that urchins and chitons can be redundant in the maintenance of available space, and highlight the value of drawing conclusions from experimental manipulations within an extended temporal context.

  2. The specificity of the interaction between αB-crystallin and desmin filaments and its impact on filament aggregation and cell viability

    PubMed Central

    Elliott, Jayne L.; Der Perng, Ming; Prescott, Alan R.; Jansen, Karin A.; Koenderink, Gijsje H.; Quinlan, Roy A.

    2013-01-01

    CRYAB (αB-crystallin) is expressed in many tissues and yet the R120G mutation in CRYAB causes tissue-specific pathologies, namely cardiomyopathy and cataract. Here, we present evidence to demonstrate that there is a specific functional interaction of CRYAB with desmin intermediate filaments that predisposes myocytes to disease caused by the R120G mutation. We use a variety of biochemical and biophysical techniques to show that plant, animal and ascidian small heat-shock proteins (sHSPs) can interact with intermediate filaments. Nevertheless, the mutation R120G in CRYAB does specifically change that interaction when compared with equivalent substitutions in HSP27 (R140G) and into the Caenorhabditis elegans HSP16.2 (R95G). By transient transfection, we show that R120G CRYAB specifically promotes intermediate filament aggregation in MCF7 cells. The transient transfection of R120G CRYAB alone has no significant effect upon cell viability, although bundling of the endogenous intermediate filament network occurs and the mitochondria are concentrated into the perinuclear region. The combination of R120G CRYAB co-transfected with wild-type desmin, however, causes a significant reduction in cell viability. Therefore, we suggest that while there is an innate ability of sHSPs to interact with and to bind to intermediate filaments, it is the specific combination of desmin and CRYAB that compromises cell viability and this is potentially the key to the muscle pathology caused by the R120G CRYAB. PMID:23530264

  3. The genetic covariance between life cycle stages separated by metamorphosis.

    PubMed

    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.

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

    PubMed

    Bo, Marzia; Bertolino, Marco; Borghini, Mireno; Castellano, Michela; Covazzi Harriague, Anabella; Di Camillo, Cristina Gioia; Gasparini, Gianpietro; Misic, Cristina; Povero, Paolo; Pusceddu, Antonio; Schroeder, Katrin; Bavestrello, Giorgio

    2011-02-03

    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.

  5. Specific sulfation and glycosylation-a structural combination for the anticoagulation of marine carbohydrates.

    PubMed

    Pomin, Vitor H; Mourão, Paulo A S

    2014-01-01

    Based on considered achievements of the last 25 years, specific combinations of sulfation patterns and glycosylation types have been proved to be key structural players for the anticoagulant activity of certain marine glycans. These conclusions were obtained from comparative and systematic analyses on the structure-anticoagulation relationships of chemically well-defined sulfated polysaccharides of marine invertebrates and red algae. These sulfated polysaccharides are known as sulfated fucans (SFs), sulfated galactans (SGs) and glycosaminoglycans (GAGs). The structural combinations necessary for the anticoagulant activities are the 2-sulfation in α-L-SGs, the 2,4-di-sulfation in α-L-fucopyranosyl units found as composing units of certain sea-urchin and sea-cucumber linear SFs, or as branching units of the fucosylated chondroitin sulfate, a unique GAG from sea-cucumbers. Another unique GAG type from marine organisms is the dermatan sulfate isolated from ascidians. The high levels of 4-sulfation at the galactosamine units combined with certain levels of 2-sulfation at the iduronic acid units is the anticoagulant structural requirements of these GAGs. When the backbones of red algal SGs are homogeneous, the anticoagulation is proportionally dependent of their sulfation content. Finally, 4-sulfation was observed to be the structural motif required to enhance the inhibition of thrombin via heparin cofactor-II by invertebrate SFs.

  6. Specific sulfation and glycosylation—a structural combination for the anticoagulation of marine carbohydrates

    PubMed Central

    Pomin, Vitor H.; Mourão, Paulo A. S.

    2014-01-01

    Based on considered achievements of the last 25 years, specific combinations of sulfation patterns and glycosylation types have been proved to be key structural players for the anticoagulant activity of certain marine glycans. These conclusions were obtained from comparative and systematic analyses on the structure-anticoagulation relationships of chemically well-defined sulfated polysaccharides of marine invertebrates and red algae. These sulfated polysaccharides are known as sulfated fucans (SFs), sulfated galactans (SGs) and glycosaminoglycans (GAGs). The structural combinations necessary for the anticoagulant activities are the 2-sulfation in α-L-SGs, the 2,4-di-sulfation in α-L-fucopyranosyl units found as composing units of certain sea-urchin and sea-cucumber linear SFs, or as branching units of the fucosylated chondroitin sulfate, a unique GAG from sea-cucumbers. Another unique GAG type from marine organisms is the dermatan sulfate isolated from ascidians. The high levels of 4-sulfation at the galactosamine units combined with certain levels of 2-sulfation at the iduronic acid units is the anticoagulant structural requirements of these GAGs. When the backbones of red algal SGs are homogeneous, the anticoagulation is proportionally dependent of their sulfation content. Finally, 4-sulfation was observed to be the structural motif required to enhance the inhibition of thrombin via heparin cofactor-II by invertebrate SFs. PMID:24639954

  7. Forming a tough shell via an intracellular matrix and cellular junctions in the tail epidermis of Oikopleura dioica (Chordata: Tunicata: Appendicularia)

    NASA Astrophysics Data System (ADS)

    Nakashima, Keisuke; Nishino, Atsuo; Hirose, Euichi

    2011-08-01

    A postanal tail is a major synapomorphy of the phylum Chordata, which is composed of three subphyla: Vertebrata, Cephalochordata, and Tunicata (Urochordata). Among tunicates, appendicularians are the only group that retains the tail in the adult, and the adult tail functions in locomotion and feeding in combination with a cellulose-based house structure. Given the phylogenetic position of tunicates, the appendicularian adult tail may possess ancestral features of the chordate tail. We assess the ultrastructural development of the tail epidermis of the appendicularian Oikopleura dioica. The epidermis of the larval tail is enclosed by the larval envelope, which is a thin sheet similar to the outer tunic layer of ascidian larvae. The epidermis of the adult tail seems to bear no tunic-like cellulosic integuments, and the tail fin is a simple folding of the epidermis. Every epidermal cell, except for the triangular cells at the edge of the tail fin, has a conspicuous matrix layer of fibrous content in the apical cytoplasm without enclosing membranes. The epidermis of the larval tail does not have a fibrous matrix layer, suggesting the production of the layer during larval development and metamorphosis. Zonulae adhaerentes firmly bind the epidermal cells of the adult tail to one another, and the dense microfilaments lining the cell borders constitute a mechanical support for the cell membranes. The intracellular matrix, cell junctions, and cytoskeletons probably make the tail epidermis a tough, flexible shell supporting the active beating of the oikopleuran adult tail.

  8. Ancient deuterostome origins of vertebrate brain signalling centres.

    PubMed

    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.

  9. Forming a tough shell via an intracellular matrix and cellular junctions in the tail epidermis of Oikopleura dioica (Chordata: Tunicata: Appendicularia).

    PubMed

    Nakashima, Keisuke; Nishino, Atsuo; Hirose, Euichi

    2011-08-01

    A postanal tail is a major synapomorphy of the phylum Chordata, which is composed of three subphyla: Vertebrata, Cephalochordata, and Tunicata (Urochordata). Among tunicates, appendicularians are the only group that retains the tail in the adult, and the adult tail functions in locomotion and feeding in combination with a cellulose-based house structure. Given the phylogenetic position of tunicates, the appendicularian adult tail may possess ancestral features of the chordate tail. We assess the ultrastructural development of the tail epidermis of the appendicularian Oikopleura dioica. The epidermis of the larval tail is enclosed by the larval envelope, which is a thin sheet similar to the outer tunic layer of ascidian larvae. The epidermis of the adult tail seems to bear no tunic-like cellulosic integuments, and the tail fin is a simple folding of the epidermis. Every epidermal cell, except for the triangular cells at the edge of the tail fin, has a conspicuous matrix layer of fibrous content in the apical cytoplasm without enclosing membranes. The epidermis of the larval tail does not have a fibrous matrix layer, suggesting the production of the layer during larval development and metamorphosis. Zonulae adhaerentes firmly bind the epidermal cells of the adult tail to one another, and the dense microfilaments lining the cell borders constitute a mechanical support for the cell membranes. The intracellular matrix, cell junctions, and cytoskeletons probably make the tail epidermis a tough, flexible shell supporting the active beating of the oikopleuran adult tail.

  10. FGF signaling induces mesoderm in the hemichordate Saccoglossus kowalevskii.

    PubMed

    Green, Stephen A; Norris, Rachael P; Terasaki, Mark; Lowe, Christopher J

    2013-03-01

    FGFs act in vertebrate mesoderm induction and also play key roles in early mesoderm formation in ascidians and amphioxus. However, in sea urchins initial characterizations of FGF function do not support a role in early mesoderm induction, making the ancestral roles of FGF signaling and mechanisms of mesoderm specification in deuterostomes unclear. In order to better characterize the evolution of mesoderm formation, we have examined the role of FGF signaling during mesoderm development in Saccoglossus kowalevskii, an experimentally tractable representative of hemichordates. We report the expression of an FGF ligand, fgf8/17/18, in ectoderm overlying sites of mesoderm specification within the archenteron endomesoderm. Embryological experiments demonstrate that mesoderm induction in the archenteron requires contact with ectoderm, and loss-of-function experiments indicate that both FGF ligand and receptor are necessary for mesoderm specification. fgf8/17/18 gain-of-function experiments establish that FGF8/17/18 is sufficient to induce mesoderm in adjacent endomesoderm. These experiments suggest that FGF signaling is necessary from the earliest stages of mesoderm specification and is required for all mesoderm development. Furthermore, they suggest that the archenteron is competent to form mesoderm or endoderm, and that FGF signaling from the ectoderm defines the location and amount of mesoderm. When considered in a comparative context, these data support a phylogenetically broad requirement for FGF8/17/18 signaling in mesoderm specification and suggest that FGF signaling played an ancestral role in deuterostome mesoderm formation.

  11. On a possible evolutionary link of the stomochord of hemichordates to pharyngeal organs of chordates.

    PubMed

    Satoh, Noriyuki; Tagawa, Kunifumi; Lowe, Christopher J; Yu, Jr-Kai; Kawashima, Takeshi; Takahashi, Hiroki; Ogasawara, Michio; Kirschner, Marc; Hisata, Kanako; Su, Yi-Hsien; Gerhart, John

    2014-12-01

    As a group closely related to chordates, hemichordate acorn worms are in a key phylogenic position for addressing hypotheses of chordate origins. The stomochord of acorn worms is an anterior outgrowth of the pharynx endoderm into the proboscis. In 1886 Bateson proposed homology of this organ to the chordate notochord, crowning this animal group "hemichordates." Although this proposal has been debated for over a century, the question still remains unresolved. Here we review recent progress related to this question. First, the developmental mode of the stomochord completely differs from that of the notochord. Second, comparison of expression profiles of genes including Brachyury, a key regulator of notochord formation in chordates, does not support the stomochord/notochord homology. Third, FoxE that is expressed in the stomochord-forming region in acorn worm juveniles is expressed in the club-shaped gland and in the endostyle of amphioxus, in the endostyle of ascidians, and in the thyroid gland of vertebrates. Based on these findings, together with the anterior endodermal location of the stomochord, we propose that the stomochord has evolutionary relatedness to chordate organs deriving from the anterior pharynx rather than to the notochord.

  12. Developmental toxicity of benzotriazole in the protochordate Ciona intestinalis (Chordata, Ascidiae).

    PubMed

    Kadar, Eniko; Dashfield, Sarah; Hutchinson, Thomas H

    2010-01-01

    Benzotriazoles (BT) are applied as anticorrosive and de-icing agents and have been detected in a variety of aquatic ecosystems and municipal wastewater effluents. We have assessed the developmental effects of benzotriazole (CAS number 95-14-7) to the marine invertebrate Ciona intestinalis (Chordata, Ascidiae). At 15 +/- 1 degrees C, the 24 h No-Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) values based on embryo morphological development were 100 and >100 mg L(-1), respectively (nominal concentration under static conditions). After 48 h, the NOEC and LOEC values were 10 and 32 mg L(-1), respectively. Light and electron microscopy studies on benzotriazole-exposed larva indicated that the primary target cells were the extra-embryonic test cells, which are known to play a significant apoptotic role during ascidian metamorphosis. The visible decline of test cells in benzotriazole-exposed larvae raises the possibility that the compound interferes with the regulation of embryo development in protochordates such as C. intestinalis. Further research is warranted to assess the potential longer term sublethal impacts of benzotriazole in aquatic organisms.

  13. Toxicity of Hg, Cu, Cd, and Cr on early developmental stages of Ciona intestinalis (Chordata, Ascidiacea) with potential application in marine water quality assessment.

    PubMed

    Bellas, J; Vázquez, E; Beiras, R

    2001-08-01

    The toxicity of mercury, copper, cadmium and chromium on sperm viability, fertilisation, embryogenesis and larval attachment of Ciona intestinalis was examined. Fertilisation rate (FR) showed a small decrease even at the highest metal concentration tested. The median effective concentrations (EC50) reducing rates of embryogenesis and larval attachment by 50% were 54 microg Hg/l (0.27 microM), 46 microg Cu/l (0.72 microM), 838 microg Cd/l (7.46 microM), 10,318 microg Cr/l (198 microM), and 35 microg Hg/l (0.18 microM), 34 microg Cu/l (0.54 microM) and 11,755 microg Cr/l (226 microM), respectively. Therefore, Hg is three times more toxic than Cu (on a molar basis), ca. 30 times more toxic than Cd and ca. 1000 times more toxic than Cr to early stages of C. intestinalis. Rates of larval attachment and embryogenesis were the most sensitive endpoints, although the latter is more advisable for routine assessment of seawater quality because of its greater simplicity. In addition to bivalves and sea-urchins, ascidian embryos can provide biological criteria for seawater quality standards taking into account the sensitivity of a chordate and contributing to the detection of harmful chemicals with no marked effect on the species currently in use in seawater quality bioassays.

  14. An epizootic of Florida manatees associated with a dinoflagellate bloom

    USGS Publications Warehouse

    O'Shea, T.J.; Rathbun, G.B.; Bonde, R.K.; Buergelt, C.D.; Odell, D.K.

    1991-01-01

    Over a 10-wk period in early 1982, 39 Florida manatees (Trichechus manatus latirostris) were found dead in the lower Caloosahatchee River and nearby waters of southwestern Florida. Two were killed by boats. The remainder showed no evidence of trauma. Lesions indicative of infectious agents were not identified, and bacteriological and contaminant residue findings were unremarkable. Nonspecific lesions of congestion and hemorrhage were identified in brain tissue. Numerous reports were also received of manatee morbidity. Some distressed manatees showed no biochemical lesions in clinical analyses of blood samples and recovered quickly. Timing of manatee illnesses coincided with fish and double-crested cormorant (Phalacrocorax auritus) mortality and morbidity. A widespread bloom of the dinoflagellate red tide organism (Gymnodinium breve) also coincided with these incidents. G. breve produces potent neurotoxins (brevetoxins). Circumstantial evidence links these events, and possible routes of exposure may include ingestion of filter-feeding ascidians. Ecological conditions that magnified the extent of the epizootic included an early dispersal of manatees into the area from a nearby winter aggregation site and unusually high salinities that facilitated the inshore spread of the red tide bloom. Management responses to future episodes of red tide in manatee areas are suggested.

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

    PubMed

    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.

  16. Physical association between a novel plasma-membrane structure and centrosome orients cell division

    PubMed Central

    Negishi, Takefumi; Miyazaki, Naoyuki; Murata, Kazuyoshi; Yasuo, Hitoyoshi; Ueno, Naoto

    2016-01-01

    In the last mitotic division of the epidermal lineage in the ascidian embryo, the cells divide stereotypically along the anterior-posterior axis. During interphase, we found that a unique membrane structure invaginates from the posterior to the centre of the cell, in a microtubule-dependent manner. The invagination projects toward centrioles on the apical side of the nucleus and associates with one of them. Further, a cilium forms on the posterior side of the cell and its basal body remains associated with the invagination. A laser ablation experiment suggests that the invagination is under tensile force and promotes the posterior positioning of the centrosome. Finally, we showed that the orientation of the invaginations is coupled with the polarized dynamics of centrosome movements and the orientation of cell division. Based on these findings, we propose a model whereby this novel membrane structure orchestrates centrosome positioning and thus the orientation of cell division axis. DOI: http://dx.doi.org/10.7554/eLife.16550.001 PMID:27502556

  17. Establishment and succession of an epibiotic community on chromated copper arsenate-treated wood in Mediterranean waters.

    PubMed

    Karayanni, Hera; Kormas, Konstantinos Ar; Cragg, Simon; Nicolaidou, Artemis

    2010-01-01

    Colonization and succession of an epibiotic animal community on chromated copper arsenate (CCA)-treated wood were studied for 18 months in the eastern Mediterranean (Saronikos Gulf, Aegean Sea). Pine wood panels, 200 x 100 x 25 mm, impregnated with CCA at retentions of 0, 12, 24, and 48 kg m(-3) were used. The abundance or surface coverage of the most characteristic taxa (polychaetes, mollusca, crustacea bryozoa, sponges, ascidians) was measured in situ, while 12 months after submersion two panels of each retention were removed and examined in the laboratory. A total of 26 taxa were identified, among which polychaetes of the family Serpulidae dominated. The controls carried the largest number of species (17) but the lowest number of individuals. On panels with CCA retentions of 12 and 24 kg m(-3), 14 and 16 species were observed, respectively, while at 48 kg m(-3), only 9 species were found. Only the controls were affected by boring bivalves of the family Teredinidae and started to break up within 3 months of submersion. Statistically significant differences in barnacle and polychaete abundance were found between treated and untreated panels. There were no significant differences among panels treated at the three CCA loadings. Ordination by nonmetric multidimensional scaling showed a seasonal effect on the colonization of the treated panels, with the highest recruitment during the warmer months of the study.

  18. [Massive mortality of marine invertebrates: an unprecedented event in northwestern Mediterranean].

    PubMed

    Perez, T; Garrabou, J; Sartoretto, S; Harmelin, J G; Francour, P; Vacelet, J

    2000-10-01

    An unprecedented mass mortality event has been observed at the end of the summer 1999 along the coasts of Provence (France) and Ligury (Italy). This event has severely affected a wide array of sessile filter-feeder invertebrates from hard-substratum communities, such as sponges (particularly the keratose sponges Hippospongia and Spongia), cnidarians (particularly the anthozoans Corallium, Paramuricea, Eunicella and Cladocora), bivalves, ascidians and bryozoans. Along the Provence coasts, the outbreak spread from east to west. Exceptionally high and constant temperatures of the whole water column (23-24 degrees C, for over one month, down to 40 m) could have determined an environmental context favourable to the mass mortality event. Like the thermal anomaly, the mortality is limited in depth. However, we cannot ascertain whether temperature had a direct effect on organisms or acted in synergy with a latent and/or waterborne agent (microbiological or chemical). Taking into account the global warming context in the NW-Mediterranean, monitoring programs of physical-chemical parameters and vulnerable populations should rapidly be set up.

  19. Growth and long-term somatic and germline chimerism following fusion of juvenile Botryllus schlosseri.

    PubMed

    Carpenter, Meredith A; Powell, John H; Ishizuka, Katherine J; Palmeri, Karla J; Rendulic, Snjezana; De Tomaso, Anthony W

    2011-02-01

    The colonial ascidian Botryllus schlosseri undergoes a histocompatibility reaction that can result in vascular fusion of distinct genotypes, creating a chimera. Chimerism has both potential benefits, such as an immediate increase in size that may enhance growth rates, and costs. For the latter, the presence of multiple genotypes in a chimera can lead to competition between genetically distinct stem cell lineages, resulting in complete replacement of somatic and germline tissues by a single genotype. Although fusion can occur at any point after metamorphosis, previous studies have focused on chimeras created from sexually mature adults, where no benefit to chimerism has been documented. Here we focus on the costs and benefits of fusion between juveniles, characterizing growth rates and patterns of somatic and germline chimerism after natural and controlled fusion events. We also compared outcomes between low- and high-density growth conditions, the latter more likely representative of what occurs in natural populations. We found that growth rates were density-dependent, and that only chimeras grew under high-density conditions. We also observed a positional component to a post-fusion event called resorption, indicating that extrinsic factors were important in this process. Patterns of germline and somatic chimerism and dominance in chimeras made from fused juveniles were equivalent to those after fusion of sexually mature adults, and there were no age-related differences in these processes. Finally, by using genetic markers that could retrospectively assign genotypes, we also found that the majority of individual testes in a chimera were clonally derived.

  20. Discovery of a marine bacterium producing 4-hydroxybenzoate and its alkyl esters, parabens.

    PubMed

    Peng, Xue; Adachi, Kyoko; Chen, Choryu; Kasai, Hiroaki; Kanoh, Kaneo; Shizuri, Yoshikazu; Misawa, Norihiko

    2006-08-01

    Chemically synthesized 4-hydroxybenzoate (4HBA) is widely used in the chemical and electrical industries as a material for producing polymers such as those of the liquid crystal type. Its alkyl esters, called parabens, have been the most widely used preservatives by the food and cosmetic industries. We report here for the first time a microorganism, a marine bacterium, which biosynthesizes these petrochemical products. The marine bacterial strain, A4B-17, which was found to belong to the genus Microbulbifer on the basis of its rRNA and gyrB sequences, was isolated from an ascidian in the coastal waters of Palau. Strain A4B-17 was, surprisingly, found to produce 10 mg/liter of 4HBA, together with its butyl (24 mg/liter), heptyl (0.4 mg/liter), and nonyl (6 mg/liter) esters. We therefore characterized 23 other marine bacteria belonging to the genus Microbulbifer, which our institute had previously isolated from various marine environments, and found that these bacteria also produced 4HBA, although with low production levels (less than one-fifth of that produced by A4B-17). We also show that the alkyl esters of 4HBA produced by strain A4B-17 were effective in preventing the growth of yeasts, molds, and gram-positive bacteria.

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

    PubMed

    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.

  2. Patellamide A and C biosynthesis by a microcin-like pathway in Prochloron didemni, the cyanobacterial symbiont of Lissoclinum patella

    PubMed Central

    Schmidt, Eric W.; Nelson, James T.; Rasko, David A.; Sudek, Sebastian; Eisen, Jonathan A.; Haygood, Margo G.; Ravel, Jacques

    2005-01-01

    Prochloron spp. are obligate cyanobacterial symbionts of many didemnid family ascidians. It has been proposed that the cyclic peptides of the patellamide class found in didemnid extracts are synthesized by Prochloron spp., but studies in which host and symbiont cells are separated and chemically analyzed to identify the biosynthetic source have yielded inconclusive results. As part of the Prochloron didemni sequencing project, we identified patellamide biosynthetic genes and confirmed their function by heterologous expression of the whole pathway in Escherichia coli. The primary sequence of patellamides A and C is encoded on a single ORF that resembles a precursor peptide. We propose that this prepatellamide is heterocyclized to form thiazole and oxazoline rings, and the peptide is cleaved to yield the two cyclic patellamides, A and C. This work represents the full sequencing and functional expression of a marine natural-product pathway from an obligate symbiont. In addition, a related cluster was identified in Trichodesmium erythraeum IMS101, an important bloom-forming cyanobacterium. PMID:15883371

  3. Microcyclamide Biosynthesis in Two Strains of Microcystis aeruginosa: from Structure to Genes and Vice Versa▿ †

    PubMed Central

    Ziemert, Nadine; Ishida, Keishi; Quillardet, Philippe; Bouchier, Christiane; Hertweck, Christian; de Marsac, Nicole Tandeau; Dittmann, Elke

    2008-01-01

    Comparative analysis of related biosynthetic gene clusters can provide new insights into the versatility of these pathways and allow the discovery of new natural products. The freshwater cyanobacterium Microcystis aeruginosa NIES298 produces the cytotoxic peptide microcyclamide. Here, we provide evidence that the cyclic hexapeptide is formed by a ribosomal pathway through the activity of a set of processing enzymes closely resembling those recently shown to be involved in patellamide biosynthesis in cyanobacterial symbionts of ascidians. Besides two subtilisin-type proteases and a heterocyclization enzyme, the gene cluster discovered in strain NIES298 encodes six further open reading frames, two of them without similarity to enzymes encoded by the patellamide gene cluster. Analyses of genomic data of a second cyanobacterial strain, M. aeruginosa PCC 7806, guided the discovery and structural elucidation of two novel peptides of the microcyclamide family. The identification of the microcyclamide biosynthetic genes provided an avenue by which to study the regulation of peptide synthesis at the transcriptional level. The precursor genes were strongly and constitutively expressed throughout the growth phase, excluding the autoinduction of these peptides, as has been observed for several peptide pheromone families in bacteria. PMID:18245249

  4. Structural shifts of aldehyde dehydrogenase enzymes were instrumental for the early evolution of retinoid-dependent axial patterning in metazoans

    PubMed Central

    Sobreira, Tiago J. P.; Marlétaz, Ferdinand; Simões-Costa, Marcos; Schechtman, Deborah; Pereira, Alexandre C.; Brunet, Frédéric; Sweeney, Sarah; Pani, Ariel; Aronowicz, Jochanan; Lowe, Christopher J.; Davidson, Bradley; Laudet, Vincent; Bronner, Marianne; de Oliveira, Paulo S. L.; Schubert, Michael; Xavier-Neto, José

    2011-01-01

    Aldehyde dehydrogenases (ALDHs) catabolize toxic aldehydes and process the vitamin A-derived retinaldehyde into retinoic acid (RA), a small diffusible molecule and a pivotal chordate morphogen. In this study, we combine phylogenetic, structural, genomic, and developmental gene expression analyses to examine the evolutionary origins of ALDH substrate preference. Structural modeling reveals that processing of small aldehydes, such as acetaldehyde, by ALDH2, versus large aldehydes, including retinaldehyde, by ALDH1A is associated with small versus large substrate entry channels (SECs), respectively. Moreover, we show that metazoan ALDH1s and ALDH2s are members of a single ALDH1/2 clade and that during evolution, eukaryote ALDH1/2s often switched between large and small SECs after gene duplication, transforming constricted channels into wide opened ones and vice versa. Ancestral sequence reconstructions suggest that during the evolutionary emergence of RA signaling, the ancestral, narrow-channeled metazoan ALDH1/2 gave rise to large ALDH1 channels capable of accommodating bulky aldehydes, such as retinaldehyde, supporting the view that retinoid-dependent signaling arose from ancestral cellular detoxification mechanisms. Our analyses also indicate that, on a more restricted evolutionary scale, ALDH1 duplicates from invertebrate chordates (amphioxus and ascidian tunicates) underwent switches to smaller and narrower SECs. When combined with alterations in gene expression, these switches led to neofunctionalization from ALDH1-like roles in embryonic patterning to systemic, ALDH2-like roles, suggesting functional shifts from signaling to detoxification. PMID:21169504

  5. Modelling distribution of marine benthos from hydroacoustics and underwater video

    NASA Astrophysics Data System (ADS)

    Holmes, K. W.; Van Niel, K. P.; Radford, B.; Kendrick, G. A.; Grove, S. L.

    2008-08-01

    Broad-scale mapping of marine benthos is required for marine resource management and conservation. This study combines textural derivatives based on bathymetry from multibeam hydroacoustics with underwater video observations to model and map sessile biota between 10- and 60-m water depth over 35 km 2 in Point Addis Marine National Park (MNP), Vic., Australia. Classification tree models and maps were developed for macroalgae (all types, mixed red algae, Ecklonia, and rhodoliths) and sessile invertebrates (all types, sponges, and ascidians). Model accuracy was tested on 25% of the video observation dataset reserved from modelling. Models fit well for most macroalgae categories (correct classification rates of 67-84%), but are not as good for sessile invertebrate classes (correct classification rates of 57-62%). The poor fit of the sessile invertebrate models may be the combined result of grouping organisms with different environmental requirements and the effect of false absences recorded during video interpretation due to poor image quality. Probability maps, binary single-class maps, and multi-class maps supply spatially explicit, detailed information on the distribution of sessile benthic biota within the MNP and provide information at a landscape-scale for ecological investigations and marine management.

  6. Characteristics of the Mesophotic Megabenthic Assemblages of the Vercelli Seamount (North Tyrrhenian Sea)

    PubMed Central

    Bo, Marzia; Bertolino, Marco; Borghini, Mireno; Castellano, Michela; Covazzi Harriague, Anabella; Di Camillo, Cristina Gioia; Gasparini, GianPietro; Misic, Cristina; Povero, Paolo; Pusceddu, Antonio; Schroeder, Katrin; Bavestrello, Giorgio

    2011-01-01

    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. PMID:21304906

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

    PubMed Central

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

    2012-01-01

    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 sub-milligram 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 (IC50, 12 and 44 nM, respectively) and mouse Neuro-2A neuroblastoma cells (IC50, 29 and 84 nM, respectively). PMID:22712890

  8. RNA interference in the appendicularian Oikopleura dioica reveals the function of the Brachyury gene.

    PubMed

    Omotezako, Tatsuya; Nishino, Atsuo; Onuma, Takeshi A; Nishida, Hiroki

    2013-07-01

    The appendicularian Oikopleura dioica is a chordate that has a remarkably simple adult body with small cell number. Its transparency, stereotyped cell lineages, short life cycle, and small genome make it a promising new experimental model of chordate developmental biology. However, the functions of its various genes are still poorly understood due to lack of a tool for suppression of gene expression. Here, we applied a double-stranded RNA (dsRNA)-based-RNA interference (RNAi) method in O. dioica. For introducing dsRNA into eggs and embryos, we injected dsRNAs into the ovary. dsRNA, which is specific to EGFP or mCherry mRNA, decreased the exogenous mRNA-derived fluorescence in both eggs and embryos. dsRNA specific to the Brachyury gene of O. dioica, which is a homologous gene of a key notochord transcriptional factor in ascidians, triggered degradation of endogenous Brachyury mRNA and induced malformation or loss of the notochord in the tail. This effect was Brachyury sequence specific, as three dsRNAs covering different sequences produced the same phenotype. The result is in accordance with its expression site and also with the key regulatory function of Brachyury in notochord formation in other chordates. RNAi in O. dioica would be a useful tool for gaining insight into the oogenesis and early developmental processes in chordates.

  9. Macrofauna associated to Mycale microsigmatosa (Porifera, Demospongiae) in Rio de Janeiro State, SE Brazil

    NASA Astrophysics Data System (ADS)

    Ribeiro, Suzi M.; Omena, Elianne P.; Muricy, Guilherme

    2003-08-01

    The macrofauna (endo- and epi-biotic) associated to the sponge Mycale ( Carmia) microsigmatosa Arndt, 1927 was studied at three sites in Rio de Janeiro State, Brazil (Arraial do Cabo, Niterói, and Rio de Janeiro). A total of 2235 individuals (over 1 mm long) of 75 invertebrate species were found associated to 19 specimens of the sponge. The most abundant and diverse taxa were the crustaceans (83%, 31 spp.), polychetes (10%, 18 spp.), and molluscs (3.7%, 15 spp.). Cnidarians, platyhelminthes, ascidians, echinoderms, pycnogonids, bryozoans, and sponges were also represented. Amphipod crustaceans were the dominant group, comprising 61% of all individuals collected. Species richness and abundance of associated fauna were highly correlated with sponge volume, but diversity and evenness were not. The site of collection influenced the species composition of the fauna associated to M. microsigmatosa but did not change significantly its diversity, abundance, richness, and dominance patterns of higher taxa. Pregnant females and juvenile stages of 29% of the species associated, including crustaceans, molluscs, echinoderms, and pycnogonids were frequently found inside M. microsigmatosa. Although many of these organisms do occur and reproduce in other habitats outside the sponge as well, M. microsigmatosa is also important for their reproduction and survivorship, thus contributing for the maintenance of biodiversity in Southwestern Atlantic sublittoral rocky shores.

  10. Microcyclamide biosynthesis in two strains of Microcystis aeruginosa: from structure to genes and vice versa.

    PubMed

    Ziemert, Nadine; Ishida, Keishi; Quillardet, Philippe; Bouchier, Christiane; Hertweck, Christian; de Marsac, Nicole Tandeau; Dittmann, Elke

    2008-03-01

    Comparative analysis of related biosynthetic gene clusters can provide new insights into the versatility of these pathways and allow the discovery of new natural products. The freshwater cyanobacterium Microcystis aeruginosa NIES298 produces the cytotoxic peptide microcyclamide. Here, we provide evidence that the cyclic hexapeptide is formed by a ribosomal pathway through the activity of a set of processing enzymes closely resembling those recently shown to be involved in patellamide biosynthesis in cyanobacterial symbionts of ascidians. Besides two subtilisin-type proteases and a heterocyclization enzyme, the gene cluster discovered in strain NIES298 encodes six further open reading frames, two of them without similarity to enzymes encoded by the patellamide gene cluster. Analyses of genomic data of a second cyanobacterial strain, M. aeruginosa PCC 7806, guided the discovery and structural elucidation of two novel peptides of the microcyclamide family. The identification of the microcyclamide biosynthetic genes provided an avenue by which to study the regulation of peptide synthesis at the transcriptional level. The precursor genes were strongly and constitutively expressed throughout the growth phase, excluding the autoinduction of these peptides, as has been observed for several peptide pheromone families in bacteria.

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

    PubMed

    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.

  12. Fgf genes in the basal chordate Ciona intestinalis.

    PubMed

    Satou, Yutaka; Imai, Kaoru S; Satoh, Nori

    2002-10-01

    In vertebrates, a number of fibroblast growth factors (FGFs) have been shown to play important roles in developing embryos and adult organisms. However, the molecular relationships of the vertebrate FGFs are not yet completely understood, partly due to the divergence of their amino acid sequences. To solve this problem, we have identified six FGF genes in a basal chordate, the ascidian Ciona intestinalis. A phylogenetic analysis confidently assigned two of them to vertebrate FGF8/17/18 and FGF11/12/13/14, respectively. Based on the presence of the conserved domains within or outside of the FGF domains, we speculate that three of the other genes are orthologous to vertebrate FGF3/7/10/22, FGF4/5/6 and FGF9/16/20, respectively, although we cannot assign the sixth member to any of the vertebrate FGFs. A survey of the raw whole genome shotgun sequences of C. intestinalis demonstrated the presence of no FGF genes other than the six genes in the genome. The identification of these six FGF genes in the basal chordate gave us an insight into the diversification of specific subfamilies of vertebrate FGFs.

  13. Genome-wide network of regulatory genes for construction of a chordate embryo.

    PubMed

    Shoguchi, Eiichi; Hamaguchi, Makoto; Satoh, Nori

    2008-04-15

    Animal development is controlled by gene regulation networks that are composed of sequence-specific transcription factors (TF) and cell signaling molecules (ST). Although housekeeping genes have been reported to show clustering in the animal genomes, whether the genes comprising a given regulatory network are physically clustered on a chromosome is uncertain. We examined this question in the present study. Ascidians are the closest living relatives of vertebrates, and their tadpole-type larva represents the basic body plan of chordates. The Ciona intestinalis genome contains 390 core TF genes and 119 major ST genes. Previous gene disruption assays led to the formulation of a basic chordate embryonic blueprint, based on over 3000 genetic interactions among 79 zygotic regulatory genes. Here, we mapped the regulatory genes, including all 79 regulatory genes, on the 14 pairs of Ciona chromosomes by fluorescent in situ hybridization (FISH). Chromosomal localization of upstream and downstream regulatory genes demonstrates that the components of coherent developmental gene networks are evenly distributed over the 14 chromosomes. Thus, this study provides the first comprehensive evidence that the physical clustering of regulatory genes, or their target genes, is not relevant for the genome-wide control of gene expression during development.

  14. Acquisition of the dorsal structures in chordate amphioxus

    PubMed Central

    Morov, Arseniy R.; Ukizintambara, Tharcisse; Sabirov, Rushan M.

    2016-01-01

    Acquisition of dorsal structures, such as notochord and hollow nerve cord, is likely to have had a profound influence upon vertebrate evolution. Dorsal formation in chordate development thus has been intensively studied in vertebrates and ascidians. However, the present understanding does not explain how chordates acquired dorsal structures. Here we show that amphioxus retains a key clue to answer this question. In amphioxus embryos, maternal nodal mRNA distributes asymmetrically in accordance with the remodelling of the cortical cytoskeleton in the fertilized egg, and subsequently lefty is first expressed in a patch of blastomeres across the equator where wnt8 is expressed circularly and which will become the margin of the blastopore. The lefty domain co-expresses zygotic nodal by the initial gastrula stage on the one side of the blastopore margin and induces the expression of goosecoid, not-like, chordin and brachyury1 genes in this region, as in the oral ectoderm of sea urchin embryos, which provides a basis for the formation of the dorsal structures. The striking similarity in the gene regulations and their respective expression domains when comparing dorsal formation in amphioxus and the determination of the oral ectoderm in sea urchin embryos suggests that chordates derived from an ambulacrarian-type blastula with dorsoventral inversion. PMID:27307516

  15. NMR structural determination of unique invertebrate glycosaminoglycans endowed with medical properties.

    PubMed

    Pomin, Vitor H

    2015-09-02

    Glycosaminoglycans (GAGs) are sulfated polysaccharides of complex structure endowed with numerous biomedical functions. Although ubiquitously distributed in vertebrates, GAGs can also occur in certain terrestrial or marine invertebrates. Solution nuclear magnetic resonance (NMR) spectroscopy has been the analytical technique mostly employed in structural characterization of GAGs from any source. This review aims at illustrating the application of NMR in structural determination of few representative invertebrate GAG examples of unique structures and endowed with therapeutic actions. They are the holothurian fucosylated chondroitin sulfate, the acharan sulfate isolated from the snail Achatina fulica, the dermatan sulfates with distinct sulfation patterns extracted from ascidian species, the sulfated glucuronic acid-containing heparan sulfate isolated from the gastropode Nodipecten nodosum, and the hybrid heparin/heparan sulfate molecule obtained from the shrimp Litopenaeus vannamei. These invertebrate GAGs exhibit distinct structures when compared to those extracted from mammalian GAGs. The distinct structures of the invertebrate GAGs lead also to different mechanisms of actions as compared to the mammalian GAG standards. Invertebrate GAGs comprise promising therapeutic candidates in fights against diseases. Solution NMR has been playing a pivotal role in this carbohydrate-based drug research, discovery and development.

  16. Megalodicopia hians in the Monterey submarine canyon: Distribution, larval development, and culture

    NASA Astrophysics Data System (ADS)

    Havenhand, Jon. N.; Matsumoto, George I.; Seidel, Ed

    2006-02-01

    The exclusively deep-sea ascidian family Octacnemidae comprises several genera in which the oral siphon has hypertrophied to form two large lips which create an "oral hood" capable of capturing motile prey. Megalodicopia hians is typical of this carnivorous family and has been reported to prey upon small epibenthic crustaceans. Distribution of M. hians in the Monterey Canyon system (36°45'N, 122°00'W) (California) was determined with remotely operated vehicles. M. hians was found sparsely to depths of at least 3800 m throughout the canyon; however, abundance was greatest within the oxygen-minimum zone (400-800 m). Eggs, sperm, and recently fertilized embryos were obtained repeatedly from adults returned to the laboratory in vivo, indicating that this species free-spawns routinely. Overall egg diameter (ovum plus chorion, plus follicle cells) was 175-190 μm—considerably smaller than previously reported for this species. Embryonic development at temperature and oxygen concentrations equivalent to the oxygen-minimum zone was 2-4 d and, embryos gave rise to typical phlebobranch "simple" tadpole larvae. Larval period was extremely variable, and settlement/metamorphosis occurred up to 3 months post-hatching. These results are discussed within the context of settlement-site selection and fertilization ecology of the species.

  17. Spherulization as a process for the exudation of chemical cues by the encrusting sponge C. crambe

    PubMed Central

    Ternon, Eva; Zarate, Lina; Chenesseau, Sandrine; Croué, Julie; Dumollard, Rémi; Suzuki, Marcelino T.; Thomas, Olivier P.

    2016-01-01

    Ecological interactions in the marine environment are now recognized to be partly held by chemical cues produced by marine organisms. In particular, sponges are sessile animals thought to rely on the bioactive substances they synthesize to ensure their development and defense. However, the mechanisms leading the sponges to use their specialized metabolites as chemical cues remain unknown. Here we report the constant release of bioactive polycyclic guanidinic alkaloids by the Mediterranean sponge Crambe crambe into the dissolved and the particulate phases using a targeted metabolomics study. These compounds were proven to be stored into already described specialized (spherulous) sponge cells and dispersed into the water column after release through the sponge exhaling channels (oscula), leading to a chemical shield surrounding the sponge. Low concentrations of these compounds were demonstrated to have teratogenic effects on embryos of a common sea squirt (ascidian). This mechanism of action called spherulization may therefore contribute to the ecological success of encrusting sponges that need to extend their substrate cover to expand. PMID:27381941

  18. Effects of metals and sediment particle size on the species composition of the epifauna of Pinna bicolor near a lead smelter, Spencer Gulf, South Australia

    NASA Astrophysics Data System (ADS)

    Ward, Trevor J.; Young, Peter C.

    1984-01-01

    Pinna bicolor (Mollusca: Pelecypoda) were transplanted between four sites near a lead smelter. The species composition of their epifauna (sessile and mobile) was examined in relation to characteristics of both sediments and seston at the sites. Seventy-two taxa were distinguished in the epifaunal community. Substantial differences were found in the short-term sensitivity of some of the species to concentrations of Cd, Pb and Zn in sediments and to sediment particle size. The short-term sensitivity of many species to metals or sediment particle size explained their long-term distribution pattern. Twenty-three taxa were identified as significantly characterizing the faunal differences. Of these, eleven (four molluscs, four bryozoans, two barnacles and one ascidian) were affected by both sediment metal concentration and particle size, and eight (four molluscs, one bryozoan, one polychaete, one hydroid and one barnacle) were affected by metal contamination but not particle size. Of all fauna examined, the Bryozoa were the most metal-sensitive. Four species, Smittina raigii (Bryozoa), Galeolaria sp. 1 (Polychaeta), Epopella simplex (Cirripedia) and Monia ione (Pelecypoda) were identified by their short- and long-term sensitivity to metal contamination, and absence of sensitivity to sediment particle size, as suitable species for monitoring the effects of metal contamination on the epifauna. The implications of the results for toxicity-testing are discussed.

  19. Investigating the widespread introduction of a tropical marine fouling species.

    PubMed

    Sheets, Elizabeth A; Cohen, C Sarah; Ruiz, Gregory M; da Rocha, Rosana M

    2016-04-01

    Little is known about the number and rate of introductions into terrestrial and marine tropical regions, and if introduction patterns and processes differ from temperate latitudes. Botryllid ascidians (marine invertebrate chordates) are an interesting group to study such introduction differences because several congeners have established populations across latitudes. While temperate botryllid invasions have been repeatedly highlighted, the global spread of tropical Botrylloides nigrum (Herdman, 1886) has been largely ignored. We sampled B. nigrum from 16 worldwide warm water locations, including around the Panama Canal, one of the largest shipping hubs in the world and a possible introduction corridor. Using mitochondrial (COI) and nuclear (ANT) markers, we discovered a single species with low genetic divergence and diversity that has established in the Atlantic, Pacific, Indo-Pacific, and Mediterranean Oceans. The Atlantic Ocean contained the highest diversity and multilocus theta estimates and may be a source for introductions to other regions. A high frequency of one mitochondrial haplotype was detected in Pacific populations that may represent a recent introduction in this region. In comparison to temperate relatives, B. nigrum displayed lower (but similar to temperate Botrylloides violaceus) genetic divergence and diversity at both loci that may represent a more recent global spread or differences in introduction pressures in tropical regions. Additionally, chimeras (genetically distinct individuals sharing a single body) were detected in three populations by the mitochondrial locus and validated using cloning, and these individuals contained new haplotype diversity not detected in any other colonies.

  20. Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities.

    PubMed

    Fabricius, K E; De'ath, G; Noonan, S; Uthicke, S

    2014-01-22

    The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425-1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs.

  1. First record of massive blooming of benthic diatoms and their association with megabenthic filter feeders on the shallow seafloor of an Antarctic Fjord: Does glacier melting fuel the bloom?

    NASA Astrophysics Data System (ADS)

    Ahn, In-Young; Moon, Hye-Won; Jeon, Misa; Kang, Sung-Ho

    2016-03-01

    We report a conspicuous benthic diatom bloom on an Antarctic fjord shallow seafloor, which has not been reported elsewhere in Antarctica. A thick and massive growth of benthic diatoms was covering or being entangled with a variety of common benthic megafauna such as stalked ascidians, sponges, tubedwelling polychaetes, gastropods, bryozoans, and others. This finding is an outcome of recent investigations on benthic communities in Marian Cove, King George Island, where glacier retreat has been proceeding quickly for the past several decades. Dominance of benthic diatoms during the austral summer has been frequently reported in shallow Antarctic nearshore waters, which in turn indicates their potential as a primary food item for secondary producers living in this harsh environment. However, previous blooming records of the benthic diatoms were primarily based on data from water column samples. We are the first to report observational evidence of shallow seafloor substrates, including the massive blooming of benthic diatoms and their associations with common benthic megafauna in an Antarctic fjord.

  2. Photosynthetic unit size, carotenoids, and chlorophyll-protein composition of Prochloron sp., a prokaryotic green alga.

    PubMed

    Withers, N W; Alberte, R S; Lewin, R A; Thornber, J P; Britton, G; Goodwin, T W

    1978-05-01

    Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were beta-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome, and trihydroxy-beta-carotene; no epsilon-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to approximately 50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 +/- 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron.

  3. The Demosponge Amphimedon queenslandica: Reconstructing the Ancestral Metazoan Genome and Deciphering the Origin of Animal Multicellularity.

    PubMed

    Degnan, Bernard M; Adamska, Maja; Craigie, Alina; Degnan, Sandie M; Fahey, Bryony; Gauthier, Marie; Hooper, John N A; Larroux, Claire; Leys, Sally P; Lovas, Erica; Richards, Gemma S

    2008-12-01

    INTRODUCTIONSponges are one of the earliest branching metazoans. In addition to undergoing complex development and differentiation, they can regenerate via stem cells and can discern self from nonself ("allorecognition"), making them a useful comparative model for a range of metazoan-specific processes. Molecular analyses of these processes have the potential to reveal ancient homologies shared among all living animals and critical genomic innovations that underpin metazoan multicellularity. Amphimedon queenslandica (Porifera, Demospongiae, Haplosclerida, Niphatidae) is the first poriferan representative to have its genome sequenced, assembled, and annotated. Amphimedon exemplifies many sessile and sedentary marine invertebrates (e.g., corals, ascidians, bryozoans): They disperse during a planktonic larval phase, settle in the vicinity of conspecifics, ward off potential competitors (including incompatible genotypes), and ensure that brooded eggs are fertilized by conspecific sperm. Using genomic and expressed sequence tag (EST) resources from Amphimedon, functional genomic approaches can be applied to a wide range of ecological and population genetic processes, including fertilization, dispersal, and colonization dynamics, host-symbiont interactions, and secondary metabolite production. Unlike most other sponges, Amphimedon produce hundreds of asynchronously developing embryos and larvae year-round in distinct, easily accessible brood chambers. Embryogenesis gives rise to larvae with at least a dozen cell types that are segregated into three layers and patterned along the body axis. In this article, we describe some of the methods currently available for studying A. queenslandica, focusing on the analysis of embryos, larvae, and post-larvae.

  4. Nodal signaling and the evolution of deuterostome gastrulation.

    PubMed

    Chea, Helen K; Wright, Christopher V; Swalla, Billie J

    2005-10-01

    Chordates, including vertebrates, evolved within a group of animals called the deuterostomes. All holoblastic deuterostomes gastrulate at the vegetal pole and the blastopore becomes the anus, while a mouth is formed at the anterior or to the oral side. Nodal is a member of the TGF-beta superfamily of signaling molecules that are important in signaling between cells during many embryonic processes in vertebrate embryos. Nodal has also been found in other invertebrate deuterostomes, such as ascidians and sea urchins, but, so far, is missing in protostomes. Nodal has been shown to be particularly important in determining left-right asymmetries in vertebrate embryos, but less information is available for its developmental role in the invertebrate deuterostomes. We review gastrulation in the deuterostomes, then examine nodal expression early during mesoderm formation and later during the establishment of asymmetries in both vertebrates and invertebrates. Nodal is expressed asymmetrically on the left side in chordates and on the presumptive oral side of the embryo in echinoid echinoderms. The expression of nodal is in different germ layers in embryos of different phyla. Expression is in the ectoderm in most of the invertebrate deuterostomes, and in the mesoderm in vertebrates. We summarize the work that has been published to date, especially nodal expression in the invertebrate deuterostomes, and suggest future experiments to better understand the evolution of nodal signaling and deuterostome gastrulation.

  5. Ultrastructure of sperm, spermiogenesis, and sperm-egg interactions in selected invertebrates and lower vertebrates which use external fertilization.

    PubMed

    Koch, R A; Lambert, C C

    1990-10-01

    This review discusses the ultrastructure of sperm with reference to their development, the surface morphology of the egg, and the processes of sperm binding and penetration during fertilization. These topics are treated for selected invertebrates and lower vertebrates which live in aquatic environments and fertilize their eggs externally. Specifically, sperm eggs from cnidarians, echinoderms, decapod crustaceans, ascidians, lampreys, bony fishes, and amphibians are discussed. Sperm from the majority of these groups exhibit the classical head-midregion-tail configuration characteristic of primitive sperm. Specific variations within this general morphology have been described. The notable exceptions to the primitive-sperm paradigm are the sperm of decapod crustaceans and amphibians. Eggs from all of the animals considered are covered by complex vitelline envelopes except those of cnidarians. In general, the ultrastructural analysis of these egg envelopes shows that they are composed of fibrous subunits. Sperm bind to the vitelline envelope and then penetrate through it to fertilize the egg in all groups reviewed except fishes. In sperm ultrastructure which occur during penetration of the egg envelopes in both flagellated and non-flagellated sperm. These changes, which involve membrane fusion and reorganization as well as movement of membranous organelles, aid the sperm in reaching the actual site of gamete fusion.

  6. A cis-Regulatory Signature for Chordate Anterior Neuroectodermal Genes

    PubMed Central

    Christiaen, Lionel; Joly, Jean-Stéphane

    2010-01-01

    One of the striking findings of comparative developmental genetics was that expression patterns of core transcription factors are extraordinarily conserved in bilaterians. However, it remains unclear whether cis-regulatory elements of their target genes also exhibit common signatures associated with conserved embryonic fields. To address this question, we focused on genes that are active in the anterior neuroectoderm and non-neural ectoderm of the ascidian Ciona intestinalis. Following the dissection of a prototypic anterior placodal enhancer, we searched all genomic conserved non-coding elements for duplicated motifs around genes showing anterior neuroectodermal expression. Strikingly, we identified an over-represented pentamer motif corresponding to the binding site of the homeodomain protein OTX, which plays a pivotal role in the anterior development of all bilaterian species. Using an in vivo reporter gene assay, we observed that 10 of 23 candidate cis-regulatory elements containing duplicated OTX motifs are active in the anterior neuroectoderm, thus showing that this cis-regulatory signature is predictive of neuroectodermal enhancers. These results show that a common cis-regulatory signature corresponding to K50-Paired homeodomain transcription factors is found in non-coding sequences flanking anterior neuroectodermal genes in chordate embryos. Thus, field-specific selector genes impose architectural constraints in the form of combinations of short tags on their target enhancers. This could account for the strong evolutionary conservation of the regulatory elements controlling field-specific selector genes responsible for body plan formation. PMID:20419150

  7. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem

    PubMed Central

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K. A.; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-01-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a “filter feeders–ascidian domination” to a “mixed assemblage” suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP. PMID:26702429

  8. Evolutionary origins of the vertebrate heart: Specification of the cardiac lineage in Ciona intestinalis

    PubMed Central

    Davidson, Brad; Levine, Michael

    2003-01-01

    Here we exploit the extensive cell lineage information and streamlined genome of the ascidian, Ciona intestinalis, to investigate heart development in a basal chordate. Several cardiac genes were analyzed, including the sole Ciona ortholog of the Drosophila tinman gene, and tissue-specific enhancers were isolated for some of the genes. Conserved sequence motifs within these enhancers facilitated the isolation of a heart enhancer for the Ciona Hand-like gene. Altogether, these studies provide a regulatory framework for the differentiation of the cardiac mesoderm, beginning at the 110-cell stage, and extending through the fusion of cardiac progenitors during tail elongation. The cardiac lineage shares a common origin with the germ line, and zygotic transcription is first detected in the heart progenitors only after its separation from the germ line at the 64-cell stage. We propose that germ-line determinants influence the specification of the cardiac mesoderm, both by inhibiting inductive signals required for the development of noncardiac mesoderm lineages, and by providing a localized source of Wnt-5 and other signals required for heart development. We discuss the possibility that the germ line also influences the specification of the vertebrate heart. PMID:14500781

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

    PubMed

    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.

  10. Ephrin-mediated restriction of ERK1/2 activity delimits the number of pigment cells in the Ciona CNS.

    PubMed

    Haupaix, Nicolas; Abitua, Philip B; Sirour, Cathy; Yasuo, Hitoyoshi; Levine, Michael; Hudson, Clare

    2014-10-01

    Recent evidence suggests that ascidian pigment cells are related to neural crest-derived melanocytes of vertebrates. Using live-imaging, we determine a revised cell lineage of the pigment cells in Ciona intestinalis embryos. The neural precursors undergo successive rounds of anterior-posterior (A-P) oriented cell divisions, starting at the blastula 64-cell stage. A previously unrecognized fourth A-P oriented cell division in the pigment cell lineage leads to the generation of the post-mitotic pigment cell precursors. We provide evidence that MEK/ERK signals are required for pigment cell specification until approximately 30min after the final cell division has taken place. Following each of the four A-P oriented cell divisions, ERK1/2 is differentially activated in the posterior sister cells, into which the pigment cell lineage segregates. Eph/ephrin signals are critical during the third A-P oriented cell division to spatially restrict ERK1/2 activation to the posterior daughter cell. Targeted inhibition of Eph/ephrin signals results in, at neurula stages, anterior expansion of both ERK1/2 activation and a pigment cell lineage marker and subsequently, at larval stages, supernumerary pigment cells. We discuss the implications of these findings with respect to the evolution of the vertebrate neural crest.

  11. Investigation of Indolglyoxamide and Indolacetamide Analogues of Polyamines as Antimalarial and Antitrypanosomal Agents

    PubMed Central

    Wang, Jiayi; Kaiser, Marcel; Copp, Brent R.

    2014-01-01

    Pure compound screening has previously identified the indolglyoxylamidospermidine ascidian metabolites didemnidine A and B (2 and 3) to be weak growth inhibitors of Trypanosoma brucei rhodesiense (IC50 59 and 44 μM, respectively) and Plasmodium falciparum (K1 dual drug resistant strain) (IC50 41 and 15 μM, respectively), but lacking in selectivity (L6 rat myoblast, IC50 24 μM and 25 μM, respectively). To expand the structure–activity relationship of this compound class towards both parasites, we have prepared and biologically tested a library of analogues that includes indoleglyoxyl and indoleacetic “capping acids”, and polyamines including spermine (PA3-4-3) and extended analogues PA3-8-3 and PA3-12-3. 7-Methoxy substituted indoleglyoxylamides were typically found to exhibit the most potent antimalarial activity (IC50 10–92 nM) but with varying degrees of selectivity versus the L6 rat myoblast cell line. A 6-methoxyindolglyoxylamide analogue was the most potent growth inhibitor of T. brucei (IC50 0.18 μM) identified in the study: it, however, also exhibited poor selectivity (L6 IC50 6.0 μM). There was no apparent correlation between antimalarial and anti-T. brucei activity in the series. In vivo evaluation of one analogue against Plasmodium berghei was undertaken, demonstrating a modest 20.9% reduction in parasitaemia. PMID:24879541

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

    PubMed Central

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

    2016-01-01

    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. DOI: http://dx.doi.org/10.7554/eLife.16962.001 PMID:27921996

  13. Caprellids (Crustacea: Amphipoda) from India

    NASA Astrophysics Data System (ADS)

    Guerra-García, J. M.; Ganesh, T.; Jaikumar, M.; Raman, A. V.

    2010-12-01

    The caprellid fauna of India is investigated. A total of 538 samples (including algae, seagrasses, sponges, hydroids, ascidians, bryozoans, encrusted dead corals, coral rubble, fine and coarse sediments) were collected from 39 stations along the coast of India, covering a wide diversity of habitats from intertidal to 12 m water depth. A new species ( Jigurru longimanus n.sp.) is described, and figures of the 11 valid species reported so far from India are given together with a key for their identification. No caprellids were found in sediments from the northeast (16-20ºN) coast of India while they were abundant in the southeast and west coast. Decreases in salinity due to river discharges associated with lower values of oxygen, higher water temperatures and lower nutrient inputs along the east coast could explain these differences in caprellid composition between the two coastlines. Significantly, lower abundance of caprellids in India, as in other tropical ecosystems, is probably related to the lack of species belonging to the genus Caprella, which reach very high abundances in temperate waters.

  14. Pattern of Brachyury gene expression in starfish embryos resembles that of hemichordate embryos but not of sea urchin embryos.

    PubMed

    Shoguchi, E; Satoh, N; Maruyama, Y K

    1999-04-01

    Echinoderms, hemichordates and chordates are deuterostomes and share a number of developmental features. The Brachyury gene is responsible for formation of the notochord, the most defining feature of chordates, and thus may be a key to understanding the origin and evolution of the chordates. Previous studies have shown that the ascidian Brachyury (As-T and Ci-Bra) is expressed in the notochord and that a sea urchin Brachyury (HpTa) is expressed in the secondary mesenchyme founder cells. A recent study by [Tagawa et al. (1998)], however, revealed that a hemichordate Brachyury (PfBra) is expressed in a novel pattern in an archenteron invagination region and a stomodaeum invagination region in the gastrula. The present study demonstrated that the expression pattern of Brachyury (ApBra) of starfish embryos resembles that of PfBra in hemichordate embryos but not of HpTa in sea urchin embryos. Namely, ApBra is expressed in an archenteron invagination region and a stomodaeum invagination region.

  15. Localization of antimicrobial peptides in the tunic of Ciona intestinalis (Ascidiacea, Tunicata) and their involvement in local inflammatory-like reactions

    PubMed Central

    Di Bella, M.A.; Fedders, H.; De Leo, G.; Leippe, M.

    2011-01-01

    Tunicates comprising a wide variety of different species synthesize antimicrobial peptides as important effector molecules of the innate immune system. Recently, two putative gene families coding for antimicrobial peptides were identified in the expressed sequence tag database of the tunicate Ciona intestinalis. Two synthetic peptides representing the cationic core region of one member of each of the families displayed potent antibacterial and antifungal activities. Moreover, the natural peptides were demonstrated to be synthesized and stored in distinct hemocyte types. Here, we investigated the presence of these natural peptides, namely Ci-MAM-A and Ci-PAP-A, in the tunic of C. intestinalis considering that the ascidian tunic is a body surface barrier exposed to constant microbial assault. Furthermore, as the tunic may represent a major route of entry for pathogen invasion after its damage we monitored the location of these peptides upon a local inflammatory-like reaction induced by injection of foreign cells. Using immunocytochemistry and electron microscopy both peptides were localized to the tunic and were massively present in granulocytes of inflamed tissue. Conclusively, antimicrobial peptides may constitute a chemical barrier within the tunic of urochordates. PMID:24371555

  16. Toll-Like Receptors of Deuterostome Invertebrates

    PubMed Central

    Satake, Honoo; Sekiguchi, Toshio

    2012-01-01

    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, the ascidian Ciona intestinalis, was found to possess only two TLR genes. Moreover, Ciona TLRs, Ci-TLR1 and Ci-TLR2, 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 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 among deuterostome invertebrates, and provide insight into an evolutionary process of TLRs. PMID:22566918

  17. Global Diversity of Ascidiacea

    PubMed Central

    Shenkar, Noa; Swalla, Billie J.

    2011-01-01

    The class Ascidiacea presents fundamental opportunities for research in the fields of development, evolution, ecology, natural products and more. This review provides a comprehensive overview of the current knowledge regarding the global biodiversity of the class Ascidiacea, focusing in their taxonomy, main regions of biodiversity, and distribution patterns. Based on analysis of the literature and the species registered in the online World Register of Marine Species, we assembled a list of 2815 described species. The highest number of species and families is found in the order Aplousobranchia. Didemnidae and Styelidae families have the highest number of species with more than 500 within each group. Sixty percent of described species are colonial. Species richness is highest in tropical regions, where colonial species predominate. In higher latitudes solitary species gradually contribute more to the total species richness. We emphasize the strong association between species richness and sampling efforts, and discuss the risks of invasive species. Our inventory is certainly incomplete as the ascidian fauna in many areas around the world is relatively poorly known, and many new species continue to be discovered and described each year. PMID:21701684

  18. Nodal signalling and asymmetry of the nervous system.

    PubMed

    Signore, Iskra A; Palma, Karina; Concha, Miguel L

    2016-12-19

    The role of Nodal signalling in nervous system asymmetry is still poorly understood. Here, we review and discuss how asymmetric Nodal signalling controls the ontogeny of nervous system asymmetry using a comparative developmental perspective. A detailed analysis of asymmetry in ascidians and fishes reveals a critical context-dependency of Nodal function and emphasizes that bilaterally paired and midline-unpaired structures/organs behave as different entities. We propose a conceptual framework to dissect the developmental function of Nodal as asymmetry inducer and laterality modulator in the nervous system, which can be used to study other types of body and visceral organ asymmetries. Using insights from developmental biology, we also present novel evolutionary hypotheses on how Nodal led the evolution of directional asymmetry in the brain, with a particular focus on the epithalamus. We intend this paper to provide a synthesis on how Nodal signalling controls left-right asymmetry of the nervous system.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

  19. Bioactive Peptides and Depsipeptides with Anticancer Potential: Sources from Marine Animals

    PubMed Central

    Suarez-Jimenez, Guadalupe-Miroslava; Burgos-Hernandez, Armando; Ezquerra-Brauer, Josafat-Marina

    2012-01-01

    Biologically active compounds with different modes of action, such as, antiproliferative, antioxidant, antimicrotubule, have been isolated from marine sources, specifically algae and cyanobacteria. Recently research has been focused on peptides from marine animal sources, since they have been found as secondary metabolites from sponges, ascidians, tunicates, and mollusks. The structural characteristics of these peptides include various unusual amino acid residues which may be responsible for their bioactivity. Moreover, protein hydrolysates formed by the enzymatic digestion of aquatic and marine by-products are an important source of bioactive peptides. Purified peptides from these sources have been shown to have antioxidant activity and cytotoxic effect on several human cancer cell lines such as HeLa, AGS, and DLD-1. These characteristics imply that the use of peptides from marine sources has potential for the prevention and treatment of cancer, and that they might also be useful as molecular models in anticancer drug research. This review focuses on the latest studies and critical research in this field, and evidences the immense potential of marine animals as bioactive peptide sources. PMID:22822350

  20. Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities

    PubMed Central

    Fabricius, K. E.; De'ath, G.; Noonan, S.; Uthicke, S.

    2014-01-01

    The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425–1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs. PMID:24307670

  1. Tunicates: exploring the sea shores and roaming the open ocean. A tribute to Thomas Huxley

    PubMed Central

    Lemaire, Patrick; Piette, Jacques

    2015-01-01

    This review is a tribute to the remarkable contributions of Thomas Huxley to the biology of tunicates, the likely sister group of vertebrates. In 1851, the great biologist and philosopher published two landmark papers on pelagic tunicates in the Philosophical Transactions of the Royal Society. They were dedicated to the description of the adult anatomy and life cycle of thaliaceans and appendicularians, the pelagic relatives of ascidians. In the first part of this review, we discuss the novel anatomical observations and evolutionary hypotheses made by Huxley, which would have a lasting influence on tunicate biology. We also briefly comment on the more philosophical reflections of Huxley on individuality. In the second part, we stress the originality and relevance of past and future studies of tunicates in the resolution of major biological issues. In particular, we focus on the complex relationship between genotype and phenotype and the phenomenon of developmental system drift. We propose that more than 150 years after Huxley's papers, tunicate embryos are still worth studying in their own right, independently of their evolutionary proximity to vertebrates, as they provide original and crucial insights into the process of animal evolution. Tunicates are still at the forefront of biological research. PMID:26085517

  2. Biochemical and toxicological evaluation of nano-heparins in cell functional properties, proteasome activation and expression of key matrix molecules.

    PubMed

    Piperigkou, Zoi; Karamanou, Konstantina; Afratis, Nikolaos A; Bouris, Panagiotis; Gialeli, Chrysostomi; Belmiro, Celso L R; Pavão, Mauro S G; Vynios, Dimitrios H; Tsatsakis, Aristidis M

    2016-01-05

    The glycosaminoglycan heparin and its derivatives act strongly on blood coagulation, controlling the activity of serine protease inhibitors in plasma. Nonetheless, there is accumulating evidence highlighting different anticancer activities of these molecules in numerous types of cancer. Nano-heparins may have great biological significance since they can inhibit cell proliferation and invasion as well as inhibiting proteasome activation. Moreover, they can cause alterations in the expression of major modulators of the tumor microenvironment, regulating cancer cell behavior. In the present study, we evaluated the effects of two nano-heparin formulations: one isolated from porcine intestine and the other from the sea squirt Styela plicata, on a breast cancer cell model. We determined whether these nano-heparins are able to affect cell proliferation, apoptosis and invasion, as well as proteasome activity and the expression of extracellular matrix molecules. Specifically, we observed that nano-Styela compared to nano-Mammalian analogue has higher inhibitory role on cell proliferation, invasion and proteasome activity. Moreover, nano-Styela regulates cell apoptosis, expression of inflammatory molecules, such as IL-6 and IL-8 and reduces the expression levels of extracellular matrix macromolecules, such as the proteolytic enzymes MT1-MMP, uPA and the cell surface proteoglycans syndecan-1 and -2, but not on syndecan-4. The observations reported in the present article indicate that nano-heparins and especially ascidian heparin are effective agents for heparin-induced effects in critical cancer cell functions, providing an important possibility in pharmacological targeting.

  3. Habitat-associations of turban snails on intertidal and subtidal rocky reefs.

    PubMed

    Smoothey, Amy F

    2013-01-01

    Patchiness of habitat has important influences on distributions and abundances of organisms. Given the increasing threat of loss and alteration of habitats due to pressures associated with humans, there is a need for ecologists to understand species' requirements for habitat and to predict changes to taxa under various future environmental conditions. This study tested hypotheses about the generality of patterns described for one species of marine intertidal turban snail for a different, yet closely-related species in subtidal habitats along the coast of New South Wales, Australia. These two closely-related species live in similar habitats, yet under quite different conditions, which provided an opportunity to investigate how similar types of habitats influence patterns of distribution, abundance and size-structure in intertidal versus subtidal environments. For each species, there were similar associations between biogenically structured habitat and densities. The intertidal species, Turbo undulates, were more abundant, with greater proportions of small individuals in habitats formed by the canopy-forming alga, Hormosira banksii, the solitary ascidian, Pyura stolonifera or the turfing red alga, Corallina officinalis compared to simple habitat (bare rock). Similarly, more Turbo torquatus were found in biogenically structured subtidal habitat, i.e. canopy-forming algae, Ecklonia radiata, mixed algal communities ('fringe'), or turfing red algae (Corallina officinalis and Amphiroa aniceps) than where habitat is simple (barrens). Small T. torquatus were more abundant in areas of turf and 'fringe', while large snails were more abundant in areas of kelp and barrens. These patterns were found at each location sampled (i.e. eight intertidal and two subtidal rocky reefs) and at all times of sampling, across each environment. This study highlighted the consistent influence of biogenically structured habitats on the distribution, abundance and size-structure of intertidal and

  4. The apoptotic initiator caspase-8: its functional ubiquity and genetic diversity during animal evolution.

    PubMed

    Sakamaki, Kazuhiro; Shimizu, Kouhei; Iwata, Hiroaki; Imai, Kenichiro; Satou, Yutaka; Funayama, Noriko; Nozaki, Masami; Yajima, Mamiko; Nishimura, Osamu; Higuchi, Mayura; Chiba, Kumiko; Yoshimoto, Michi; Kimura, Haruna; Gracey, Andrew Y; Shimizu, Takashi; Tomii, Kentaro; Gotoh, Osamu; Akasaka, Koji; Sawasaki, Tatsuya; Miller, David J

    2014-12-01

    The caspases, a family of cysteine proteases, play multiple roles in apoptosis, inflammation, and cellular differentiation. Caspase-8 (Casp8), which was first identified in humans, functions as an initiator caspase in the apoptotic signaling mediated by cell-surface death receptors. To understand the evolution of function in the Casp8 protein family, casp8 orthologs were identified from a comprehensive range of vertebrates and invertebrates, including sponges and cnidarians, and characterized at both the gene and protein levels. Some introns have been conserved from cnidarians to mammals, but both losses and gains have also occurred; a new intron arose during teleost evolution, whereas in the ascidian Ciona intestinalis, the casp8 gene is intronless and is organized in an operon with a neighboring gene. Casp8 activities are near ubiquitous throughout the animal kingdom. Exogenous expression of a representative range of nonmammalian Casp8 proteins in cultured mammalian cells induced cell death, implying that these proteins possess proapoptotic activity. The cnidarian Casp8 proteins differ considerably from their bilaterian counterparts in terms of amino acid residues in the catalytic pocket, but display the same substrate specificity as human CASP8, highlighting the complexity of spatial structural interactions involved in enzymatic activity. Finally, it was confirmed that the interaction with an adaptor molecule, Fas-associated death domain protein, is also evolutionarily ancient. Thus, despite structural diversity and cooption to a variety of new functions, the ancient origins and near ubiquitous distribution of this activity across the animal kingdom emphasize the importance and utility of Casp8 as a central component of the metazoan molecular toolkit.

  5. On the evolutionary significance and metal-binding characteristics of a monolobal transferrin from Ciona intestinalis

    PubMed Central

    Tinoco, Arthur D.; Peterson, Cynthia W.; Lucchese, Baldo; Doyle, Robert P.; Valentine, Ann M.

    2008-01-01

    Transferrins are a family of proteins that bind and transport Fe(III). Modern transferrins are typically bilobal and are believed to have evolved from an ancient gene duplication of a monolobal form. A novel monolobal transferrin, nicatransferrin (nicaTf), was identified in the primitive ascidian species Ciona intestinalis that possesses the characteristic features of the proposed ancestral Tf protein. In this work, nicaTf was expressed in Pichia pastoris. Extensive solution studies were performed on nicaTf, including UV-vis, fluorescence, CD, EPR and NMR spectroscopies, and electrospray time-of-flight mass spectrometry. The expressed protein is nonglycosylated, unlike the protein isolated from the organism. This property does not affect its ability to bind Fe(III). However, Fe(III)-bound nicaTf displays important spectral differences from other Fe(III)-bound transferrins, which are likely the consequence of differences in metal coordination. Coordination differences could also account for the weaker affinity of nicaTf for Fe(III) (log K = 18.5) compared with bilobal human serum transferrin (HsTf) (log K = 22.5 and 21.4). The Fe–nicaTf complex is not labile, as indicated by slow metal removal kinetics by the high-affinity chelator tiron at pH 7.4. The protein alternatively binds up to one equivalent of Ti(IV) or V(V), which suggests that it may transport nonferric metals. These solution studies provide insight into the structure and function of the primitive monolobal transferrin of C. intestinalis for comparison with higher order bilobal transferrins. They suggest that a major advantage for the evolution of modern transferrins, dominantly of bilobal form, is stronger Fe(III) affinity because of cooperativity. PMID:18287008

  6. The repertoire of G protein-coupled receptors in the sea squirt Ciona intestinalis

    PubMed Central

    2008-01-01

    Background G protein-coupled receptors (GPCRs) constitute a large family of integral transmembrane receptor proteins that play a central role in signal transduction in eukaryotes. The genome of the protochordate Ciona intestinalis has a compact size with an ancestral complement of many diversified gene families of vertebrates and is a good model system for studying protochordate to vertebrate diversification. An analysis of the Ciona repertoire of GPCRs from a comparative genomic perspective provides insight into the evolutionary origins of the GPCR signalling system in vertebrates. Results We have identified 169 gene products in the Ciona genome that code for putative GPCRs. Phylogenetic analyses reveal that Ciona GPCRs have homologous representatives from the five major GRAFS (Glutamate, Rhodopsin, Adhesion, Frizzled and Secretin) families concomitant with other vertebrate GPCR repertoires. Nearly 39% of Ciona GPCRs have unambiguous orthologs of vertebrate GPCR families, as defined for the human, mouse, puffer fish and chicken genomes. The Rhodopsin family accounts for ~68% of the Ciona GPCR repertoire wherein the LGR-like subfamily exhibits a lineage specific gene expansion of a group of receptors that possess a novel domain organisation hitherto unobserved in metazoan genomes. Conclusion Comparison of GPCRs in Ciona to that in human reveals a high level of orthology of a protochordate repertoire with that of vertebrate GPCRs. Our studies suggest that the ascidians contain the basic ancestral complement of vertebrate GPCR genes. This is evident at the subfamily level comparisons since Ciona GPCR sequences are significantly analogous to vertebrate GPCR subfamilies even while exhibiting Ciona specific genes. Our analysis provides a framework to perform future experimental and comparative studies to understand the roles of the ancestral chordate versions of GPCRs that predated the divergence of the urochordates and the vertebrates. PMID:18452600

  7. miR-124 function during Ciona intestinalis neuronal development includes extensive interaction with the Notch signaling pathway.

    PubMed

    Chen, Jerry S; Pedro, Matthew San; Zeller, Robert W

    2011-11-01

    The nervous system-enriched microRNA miR-124 is necessary for proper nervous system development, although the mechanism remains poorly understood. Here, through a comprehensive analysis of miR-124 and its gene targets, we demonstrate that, in the chordate ascidian Ciona intestinalis, miR-124 plays an extensive role in promoting nervous system development. We discovered that feedback interaction between miR-124 and Notch signaling regulates the epidermal-peripheral nervous system (PNS) fate choice in tail midline cells. Notch signaling silences miR-124 in epidermal midline cells, whereas in PNS midline cells miR-124 silences Notch, Neuralized and all three Ciona Hairy/Enhancer-of-Split genes. Furthermore, ectopic expression of miR-124 is sufficient to convert epidermal midline cells into PNS neurons, consistent with a role in modulating Notch signaling. More broadly, genome-wide target extraction with validation using an in vivo tissue-specific sensor assay indicates that miR-124 shapes neuronal progenitor fields by downregulating non-neural genes, notably the muscle specifier Macho-1 and 50 Brachyury-regulated notochord genes, as well as several anti-neural factors including SCP1 and PTBP1. 3'UTR conservation analysis reveals that miR-124 targeting of SCP1 is likely to have arisen as a shared, derived trait in the vertebrate/tunicate ancestor and targeting of PTBP1 is conserved among bilaterians except for ecdysozoans, while extensive Notch pathway targeting appears to be Ciona specific. Altogether, our results provide a comprehensive insight into the specific mechanisms by which miR-124 promotes neuronal development.

  8. Biomixing generated by benthic filter feeders: a diffusion model for near-bottom phytoplankton depletion

    NASA Astrophysics Data System (ADS)

    Larsena, Poul S.; Riisgård, Hans Ulrik

    1997-05-01

    Transient concentration distributions of flagellate cells ( Rhodomonas sp.) previously measured by Riisgård and co-workers in laboratory experiments have been examined to develop a diffusion model for the process of phytoplankton depletion in stagnant seawater above populations of benthic filter 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. diversicolor, having inhalant and exhalant openings flush with the sediment surface and a moderate exhalant jet velocity of ˜0.01 m s -1, concentration boundary layer growth is retarded and limited by the low values of diffusivity prevailing at heights greater >˜0.05 m above the bottom. For C. intestinalis, having inhalant and exhalant openings situated ˜0.05-0.1 m above the bottom and a higher and inclined exhalant jet velocity of ˜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 biomixing in this layer. Numerical predictions of concentration distributions reproduce essential features of experiments, and suggest near-bottom values of effective diffusivity of 0.3 x 10 -6 and 150 x 10 -6 m 2 s -1, for N. diversicolor and C. intestinalis, respectively. It is suggested that the latter value is so large that the induced mixing should be accounted for in modelling benthic concentration boundary layers under flow conditions.

  9. High-throughput sequence analysis of Ciona intestinalis SL trans-spliced mRNAs: alternative expression modes and gene function correlates.

    PubMed

    Matsumoto, Jun; Dewar, Ken; Wasserscheid, Jessica; Wiley, Graham B; Macmil, Simone L; Roe, Bruce A; Zeller, Robert W; Satou, Yutaka; Hastings, Kenneth E M

    2010-05-01

    Pre-mRNA 5' spliced-leader (SL) trans-splicing occurs in some metazoan groups but not in others. Genome-wide characterization of the trans-spliced mRNA subpopulation has not yet been reported for any metazoan. We carried out a high-throughput analysis of the SL trans-spliced mRNA population of the ascidian tunicate Ciona intestinalis by 454 Life Sciences (Roche) pyrosequencing of SL-PCR-amplified random-primed reverse transcripts of tailbud embryo RNA. We obtained approximately 250,000 high-quality reads corresponding to 8790 genes, approximately 58% of the Ciona total gene number. The great depth of this data revealed new aspects of trans-splicing, including the existence of a significant class of "infrequently trans-spliced" genes, accounting for approximately 28% of represented genes, that generate largely non-trans-spliced mRNAs, but also produce trans-spliced mRNAs, in part through alternative promoter use. Thus, the conventional qualitative dichotomy of trans-spliced versus non-trans-spliced genes should be supplanted by a more accurate quantitative view recognizing frequently and infrequently trans-spliced gene categories. Our data include reads representing approximately 80% of Ciona frequently trans-spliced genes. Our analysis also revealed significant use of closely spaced alternative trans-splice acceptor sites which further underscores the mechanistic similarity of cis- and trans-splicing and indicates that the prevalence of +/-3-nt alternative splicing events at tandem acceptor sites, NAGNAG, is driven by spliceosomal mechanisms, and not nonsense-mediated decay, or selection at the protein level. The breadth of gene representation data enabled us to find new correlations between trans-splicing status and gene function, namely the overrepresentation in the frequently trans-spliced gene class of genes associated with plasma/endomembrane system, Ca(2+) homeostasis, and actin cytoskeleton.

  10. Evolution of Ciona intestinalis Tumor necrosis factor alpha (CiTNFα): Polymorphism, tissues expression, and 3D modeling.

    PubMed

    Vizzini, Aiti; Giovanna, Parisi Maria; Cardinale, Laura; Testasecca, Lelia; Cammarata, Matteo

    2017-02-01

    Although the Tumor necrosis factor gene superfamily seems to be very conserved in vertebrates, phylogeny, tissue expression, genomic and gene organization, protein domains and polymorphism analyses showed that a strong change has happened mostly in invertebrates in which protochordates were a constraint during the immune-molecules history and evolution. RT PCR was used to investigate differential gene expression in different tissues. The expression shown was greater in the pharynx. Single-nucleotide polymorphism has been investigated in Ciona intestinalis Tumor necrosis factor alpha (CiTNFα) mRNA isolated from the pharynx of 30 ascidians collected from Licata, Sicily (Italy), by denaturing gradient gel electrophoresis (DGGE). For this analysis, CiTNFα nucleotide sequence was separated into two fragments, TNF-1 and -2, respectively, of 630 and 540 bp. We defined 23 individual DGGE patterns (named 1 to 10 for TNF-1 and 1 to 13 for TNF-2). Five patterns for TNF-1 accounted for <10% of the individuals, whereas the pattern 13 of TNF-2 accounted for >20% of the individuals. All the patterns were verified by direct sequencing. Single base-pair mutations were observed mainly within COOH-terminus, leading to 30 nucleotide sequence variants and 30 different coding sequences segregating in two main different clusters. Although most of the base mutations were silent, four propeptide variants were detected and six amino acid replacements occurred within COOH-terminus. Statistical tests for neutrality indicated negative selection pressure on signal and mature peptide domains, but possible positive selection pressure on COOH-terminus domain. Lastly we displayed the in silico 3D structure analysis including the CiTNFα variable region.

  11. Morphological Differences between Larvae of the Ciona intestinalis Species Complex: Hints for a Valid Taxonomic Definition of Distinct Species.

    PubMed

    Pennati, Roberta; Ficetola, Gentile Francesco; Brunetti, Riccardo; Caicci, Federico; Gasparini, Fabio; Griggio, Francesca; Sato, Atsuko; Stach, Thomas; Kaul-Strehlow, Sabrina; Gissi, Carmela; Manni, Lucia

    2015-01-01

    The cosmopolitan ascidian Ciona intestinalis is the most common model species of Tunicata, the sister-group of Vertebrata, and widely used in developmental biology, genomics and evolutionary studies. Recently, molecular studies suggested the presence of cryptic species hidden within the C. intestinalis species, namely C. intestinalis type A and type B. So far, no substantial morphological differences have been identified between individuals belonging to the two types. Here we present morphometric, immunohistochemical, and histological analyses, as well as 3-D reconstructions, of late larvae obtained by cross-fertilization experiments of molecularly determined type A and type B adults, sampled in different seasons and in four different localities. Our data point to quantitative and qualitative differences in the trunk shape of larvae belonging to the two types. In particular, type B larvae exhibit a longer pre-oral lobe, longer and relatively narrower total body length, and a shorter ocellus-tail distance than type A larvae. All these differences were found to be statistically significant in a Discriminant Analysis. Depending on the number of analyzed parameters, the obtained discriminant function was able to correctly classify > 93% of the larvae, with the remaining misclassified larvae attributable to the existence of intra-type seasonal variability. No larval differences were observed at the level of histology and immunohistochemical localization of peripheral sensory neurons. We conclude that type A and type B are two distinct species that can be distinguished on the basis of larval morphology and molecular data. Since the identified larval differences appear to be valid diagnostic characters, we suggest to raise both types to the rank of species and to assign them distinct names.

  12. Enhancer of zeste acts as a major developmental regulator of Ciona intestinalis embryogenesis.

    PubMed

    Le Goff, Emilie; Martinand-Mari, Camille; Martin, Marianne; Feuillard, Jérôme; Boublik, Yvan; Godefroy, Nelly; Mangeat, Paul; Baghdiguian, Stephen; Cavalli, Giacomo

    2015-08-14

    The paradigm of developmental regulation by Polycomb group (PcG) proteins posits that they maintain silencing outside the spatial expression domains of their target genes, particularly of Hox genes, starting from mid embryogenesis. The Enhancer of zeste [E(z)] PcG protein is the catalytic subunit of the PRC2 complex, which silences its targets via deposition of the H3K27me3 mark. Here, we studied the ascidian Ciona intestinalis counterpart of E(z). Ci-E(z) is detected by immunohistochemistry as soon as the 2- and 4-cell stages as a cytoplasmic form and becomes exclusively nuclear thereafter, whereas the H3K27me3 mark is detected starting from the gastrula stage and later. Morpholino invalidation of Ci-E(z) leads to the total disappearance of both Ci-E(z) protein and its H3K27me3 mark. Ci-E(z) morphants display a severe phenotype. Strikingly, the earliest defects occur at the 4-cell stage with the dysregulation of cell positioning and mitotic impairment. At later stages, Ci-E(z)-deficient embryos are affected by terminal differentiation defects of neural, epidermal and muscle tissues, by the failure to form a notochord and by the absence of caudal nerve. These major phenotypic defects are specifically rescued by injection of a morpholino-resistant Ci-E(z) mRNA, which restores expression of Ci-E(z) protein and re-deposition of the H3K27me3 mark. As observed by qPCR analyses, Ci-E(z) invalidation leads to the early derepression of tissue-specific developmental genes, whereas late-acting developmental genes are generally down-regulated. Altogether, our results suggest that Ci-E(z) plays a major role during embryonic development in Ciona intestinalis by silencing early-acting developmental genes in a Hox-independent manner.

  13. Transcriptional regulation of the peripheral nervous system in Ciona intestinalis.

    PubMed

    Joyce Tang, W; Chen, Jerry S; Zeller, Robert W

    2013-06-15

    The formation of the sensory organs and cells that make up the peripheral nervous system (PNS) relies on the activity of transcription factors encoded by proneural genes (PNGs). Although PNGs have been identified in the nervous systems of both vertebrates and invertebrates, the complexity of their interactions has complicated efforts to understand their function in the context of their underlying regulatory networks. To gain insight into the regulatory network of PNG activity in chordates, we investigated the roles played by PNG homologs in regulating PNS development of the invertebrate chordate Ciona intestinalis. We discovered that in Ciona, MyT1, Pou4, Atonal, and NeuroD-like are expressed in a sequential regulatory cascade in the developing epidermal sensory neurons (ESNs) of the PNS and act downstream of Notch signaling, which negatively regulates these genes and the number of ESNs along the tail midlines. Transgenic embryos mis-expressing any of these proneural genes in the epidermis produced ectopic midline ESNs. In transgenic embryos mis-expressing Pou4, and MyT1 to a lesser extent, numerous ESNs were produced outside of the embryonic midlines. In addition we found that the microRNA miR-124, which inhibits Notch signaling in ESNs, is activated downstream of all the proneural factors we tested, suggesting that these genes operate collectively in a regulatory network. Interestingly, these factors are encoded by the same genes that have recently been demonstrated to convert fibroblasts into neurons. Our findings suggest the ascidian PNS can serve as an in vivo model to study the underlying regulatory mechanisms that enable the conversion of cells into sensory neurons.

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

    PubMed

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

    2010-05-15

    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-17beta, 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 17beta-hydroxysteroid dehydrogenase (17beta-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 17beta-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

  15. A tale of two drug targets: the evolutionary history of BACE1 and BACE2

    PubMed Central

    Southan, Christopher; Hancock, John M.

    2013-01-01

    The beta amyloid (APP) cleaving enzyme (BACE1) has been a drug target for Alzheimer's Disease (AD) since 1999 with lead inhibitors now entering clinical trials. In 2011, the paralog, BACE2, became a new target for type II diabetes (T2DM) having been identified as a TMEM27 secretase regulating pancreatic β cell function. However, the normal roles of both enzymes are unclear. This study outlines their evolutionary history and new opportunities for functional genomics. We identified 30 homologs (UrBACEs) in basal phyla including Placozoans, Cnidarians, Choanoflagellates, Porifera, Echinoderms, Annelids, Mollusks and Ascidians (but not Ecdysozoans). UrBACEs are predominantly single copy, show 35–45% protein sequence identity with mammalian BACE1, are ~100 residues longer than cathepsin paralogs with an aspartyl protease domain flanked by a signal peptide and a C-terminal transmembrane domain. While multiple paralogs in Trichoplax and Monosiga pre-date the nervous system, duplication of the UrBACE in fish gave rise to BACE1 and BACE2 in the vertebrate lineage. The latter evolved more rapidly as the former maintained the emergent neuronal role. In mammals, Ka/Ks for BACE2 is higher than BACE1 but low ratios for both suggest purifying selection. The 5' exons show higher Ka/Ks than the catalytic section. Model organism genomes show the absence of certain BACE human substrates when the UrBACE is present. Experiments could thus reveal undiscovered substrates and roles. The human protease double-target status means that evolutionary trajectories and functional shifts associated with different substrates will have implications for the development of clinical candidates for both AD and T2DM. A rational basis for inhibition specificity ratios and assessing target-related side effects will be facilitated by a more complete picture of BACE1 and BACE2 functions informed by their evolutionary context. PMID:24381583

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

    PubMed Central

    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

  17. Regional connectivity and coastal expansion: differentiating pre-border and post-border vectors for the invasive tunicate Styela clava.

    PubMed

    Goldstien, S J; Schiel, D R; Gemmell, N J

    2010-03-01

    The dramatic increase in marine bio-invasions, particularly of non-indigenous ascidians, has highlighted the vulnerability of marine ecosystems and the productive sectors that rely on them. A critical issue in managing invasive species is determining the relative roles of ongoing introductions, versus the local movement of propagules from established source populations. Styela clava (Herdman, 1882), the Asian clubbed tunicate, once restricted to the Pacific shores of Asia and Russia, is now abundant throughout the northern and southern hemispheres and has had significant economic impact in at least one site of incursion. In 2005 S. clava was identified in New Zealand. The recent introduction of this species, coupled with its restricted distribution, provided an ideal model to compare and contrast the introduction and expansion process. In this study, the mitochondrial DNA cytochrome oxidase subunit I gene (COI) gene and 11 microsatellite markers were used to test the regional genetic structure and diversity of 318 S. clava individuals from 10 populations within New Zealand. Both markers showed significant differentiation between the northern and southern populations, indicative of minimal pre- or post-border connectivity. Additional statistics further support pre- and post-border differentiation among Port and Harbour populations (i.e. marinas and aquaculture farms). We conclude that New Zealand receives multiple introductions, and that the primary vector for pre-border incursions and post-border spread is most likely the extensive influx of recreational vessels that enter northern marinas independent of the Port. This is a timely reminder of the potential for hull-fouling organisms to expand their range as climates change and open new pathways.

  18. A tale of two drug targets: the evolutionary history of BACE1 and BACE2.

    PubMed

    Southan, Christopher; Hancock, John M

    2013-01-01

    The beta amyloid (APP) cleaving enzyme (BACE1) has been a drug target for Alzheimer's Disease (AD) since 1999 with lead inhibitors now entering clinical trials. In 2011, the paralog, BACE2, became a new target for type II diabetes (T2DM) having been identified as a TMEM27 secretase regulating pancreatic β cell function. However, the normal roles of both enzymes are unclear. This study outlines their evolutionary history and new opportunities for functional genomics. We identified 30 homologs (UrBACEs) in basal phyla including Placozoans, Cnidarians, Choanoflagellates, Porifera, Echinoderms, Annelids, Mollusks and Ascidians (but not Ecdysozoans). UrBACEs are predominantly single copy, show 35-45% protein sequence identity with mammalian BACE1, are ~100 residues longer than cathepsin paralogs with an aspartyl protease domain flanked by a signal peptide and a C-terminal transmembrane domain. While multiple paralogs in Trichoplax and Monosiga pre-date the nervous system, duplication of the UrBACE in fish gave rise to BACE1 and BACE2 in the vertebrate lineage. The latter evolved more rapidly as the former maintained the emergent neuronal role. In mammals, Ka/Ks for BACE2 is higher than BACE1 but low ratios for both suggest purifying selection. The 5' exons show higher Ka/Ks than the catalytic section. Model organism genomes show the absence of certain BACE human substrates when the UrBACE is present. Experiments could thus reveal undiscovered substrates and roles. The human protease double-target status means that evolutionary trajectories and functional shifts associated with different substrates will have implications for the development of clinical candidates for both AD and T2DM. A rational basis for inhibition specificity ratios and assessing target-related side effects will be facilitated by a more complete picture of BACE1 and BACE2 functions informed by their evolutionary context.

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

    PubMed

    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

  20. Expression of major gap junction connexin types in the working myocardium of eight chordates.

    PubMed

    Becker, D L; Cook, J E; Davies, C S; Evans, W H; Gourdie, R G

    1998-01-01

    The alpha1 connexin (connexin43) is regarded as the major gap junction protein of the myocardium because it predominates there in mammals. Here, we show that it is not the major connexin of the working myocardium in non-mammalian vertebrates, which instead express beta1-like connexins homologous to mammalian connexin32. A phylogenetic series of hearts was immunostained with seven antibodies raised against peptide sequences specific for three distinct members of the gap junction connexin family: alpha1, beta1 and alpha5 (mammalian connexin40/avian connexin42). Working myocardium from two ascidian chordates (Ciona and Mogula), a teleost (Carassius), a frog (Xenopus) and two reptiles (Anolis and Alligator) was found to express a beta1-like connexin, rather than an alpha1-like connexin. An alpha1-like connexin was nevertheless often detected in other cardiac tissues. In the chicken (by ancestry a reptile), the developing myocardium expressed a beta1-like connexin strongly on embryonic day 6 but less strongly at hatching, and minimally in the adult. Myocardial expression of alpha5 connexin increased during development, but remained strongest in the coronary vascular endothelial and cardiac conduction tissues. The arteriolar smooth muscle of the chicken expressed alpha1 connexin throughout development, but its myocardium did not. In contrast, the working myocardium of a marsupial mammal (the opossum Trichosurus) strongly expressed an alpha1 connexin just like placental mammals. These results imply that a shift from beta1 to alpha1 connexin expression in the heart occurred prior to the evolution of the opossums. The beta and alpha connexin subfamilies have different permeabilities and gating properties, and we discuss factors that might have made this shift beneficial.

  1. Morphological Differences between Larvae of the Ciona intestinalis Species Complex: Hints for a Valid Taxonomic Definition of Distinct Species

    PubMed Central

    Pennati, Roberta; Ficetola, Gentile Francesco; Brunetti, Riccardo; Caicci, Federico; Gasparini, Fabio; Griggio, Francesca; Sato, Atsuko; Stach, Thomas; Kaul-Strehlow, Sabrina; Gissi, Carmela; Manni, Lucia

    2015-01-01

    The cosmopolitan ascidian Ciona intestinalis is the most common model species of Tunicata, the sister-group of Vertebrata, and widely used in developmental biology, genomics and evolutionary studies. Recently, molecular studies suggested the presence of cryptic species hidden within the C. intestinalis species, namely C. intestinalis type A and type B. So far, no substantial morphological differences have been identified between individuals belonging to the two types. Here we present morphometric, immunohistochemical, and histological analyses, as well as 3-D reconstructions, of late larvae obtained by cross-fertilization experiments of molecularly determined type A and type B adults, sampled in different seasons and in four different localities. Our data point to quantitative and qualitative differences in the trunk shape of larvae belonging to the two types. In particular, type B larvae exhibit a longer pre-oral lobe, longer and relatively narrower total body length, and a shorter ocellus-tail distance than type A larvae. All these differences were found to be statistically significant in a Discriminant Analysis. Depending on the number of analyzed parameters, the obtained discriminant function was able to correctly classify > 93% of the larvae, with the remaining misclassified larvae attributable to the existence of intra-type seasonal variability. No larval differences were observed at the level of histology and immunohistochemical localization of peripheral sensory neurons. We conclude that type A and type B are two distinct species that can be distinguished on the basis of larval morphology and molecular data. Since the identified larval differences appear to be valid diagnostic characters, we suggest to raise both types to the rank of species and to assign them distinct names. PMID:25955391

  2. Cell cultures from marine invertebrates: new insights for capturing endless stemness.

    PubMed

    Rinkevich, Baruch

    2011-06-01

    Despite several decades of extensive research efforts, there is yet no single permanent cell line available from marine invertebrates as these cells stop dividing in vitro within 24-72 h after their isolation, starting cellular quiescence. This ubiquitous quiescent state should be modified in a way that at least some of the quiescent cells will become pluripotent, so they will have the ability to divide and become immortal. Following the above need, this essay introduces the rationale that the discipline of marine invertebrates' cell culture should gain from applying of two research routes, relevant to mammalian systems but less explored in the marine arena. The first is the use of adult stem cells (ASC) from marine organisms. Many marine invertebrate taxa maintain large pools of ASC in adulthood. Ample evidence attests that these cells from sponges, cnidarians, flatworms, crustaceans, mollusks, echinoderms, and ascidians play important roles in maintenance, regeneration, and asexual cloning, actively proliferating in vivo, resembling the vertebrates' cancer stem cells features. The second route is to target resting somatic cell constituents, manipulating them in the same way as has recently been performed on mammalian induced pluripotent stem (iPS) cells. While "iPS cells" are the outcome of an experimental manipulation, ASC are natural and rather frequent in a number of marine invertebrates. Above two cell categories reveal that there are more than a few types of seeds (cells) waiting to be sowed in the right soil (in vitro environmental conditions) for acquiring stemness and immortality. This rationale carries the potential to revolutionize the discipline of marine invertebrate cell cultures. When cultured "correctly," ASC and "iPS cells" from marine invertebrates may stay in their primitive stage and proliferate without differentiating into cells lineages, harnessing the stem cell's inherent abilities of self-replication versus differentiated progenies, toward

  3. Tango waves in a bidomain model of fertilization calcium waves

    NASA Astrophysics Data System (ADS)

    Li, Yue-Xian

    2003-12-01

    Fertilization of an egg cell is marked by one or several Ca 2+ waves that travel across the intra-cellular space, called fertilization Ca 2+ waves. Patterns of Ca 2+ waves observed in mature or immature oocytes include traveling fronts and pulses as well as concentric and spiral waves. These patterns have been studied in other excitable media in physical, chemical, and biological systems. Here, we report the discovery of a new wave phenomenon in the numerical study of a bidomain model of fertilization Ca 2+ waves. This wave is a front that propagates in a back-and-forth manner that resembles the movement of tango dancers, thus is called a tango wave. When the medium is excitable, a forward-moving tango wave can generate traveling pulses that propagate down the space without reversal. The study shows that the occurrence of tango waves is related to spatial inhomogeneity in the local dynamics. This is tested and confirmed by simulating similar waves in a medium with stationary spatial inhomogeneity. Similar waves are also obtained in a FitzHugh-Nagumo system with a linear spatial ramp. In both the bidomain model of Ca 2+ waves and the FitzHugh-Nagumo system, the front is stable when the slope of a linear ramp is large. As the slope decreases beyond a critical value, front oscillations occur. The study shows that tango waves facilitate the dispersion of localized Ca 2+. Key features of the bidomain model underlying the occurrence of tango waves are revealed. These features are commonly found in egg cells of a variety of species. Thus, we predict that tango waves can occur in real egg cells provided that a slowly varying inhomogeneity does occur following the sperm entry. The observation of tango wave-like waves in nemertean worm and ascidian eggs seems to support such a prediction.

  4. Habitat-Associations of Turban Snails on Intertidal and Subtidal Rocky Reefs

    PubMed Central

    Smoothey, Amy F.

    2013-01-01

    Patchiness of habitat has important influences on distributions and abundances of organisms. Given the increasing threat of loss and alteration of habitats due to pressures associated with humans, there is a need for ecologists to understand species' requirements for habitat and to predict changes to taxa under various future environmental conditions. This study tested hypotheses about the generality of patterns described for one species of marine intertidal turban snail for a different, yet closely-related species in subtidal habitats along the coast of New South Wales, Australia. These two closely-related species live in similar habitats, yet under quite different conditions, which provided an opportunity to investigate how similar types of habitats influence patterns of distribution, abundance and size-structure in intertidal versus subtidal environments. For each species, there were similar associations between biogenically structured habitat and densities. The intertidal species, Turbo undulates, were more abundant, with greater proportions of small individuals in habitats formed by the canopy-forming alga, Hormosira banksii, the solitary ascidian, Pyura stolonifera or the turfing red alga, Corallina officinalis compared to simple habitat (bare rock). Similarly, more Turbo torquatus were found in biogenically structured subtidal habitat, i.e. canopy-forming algae, Ecklonia radiata, mixed algal communities (‘fringe’), or turfing red algae (Corallina officinalis and Amphiroa aniceps) than where habitat is simple (barrens). Small T. torquatus were more abundant in areas of turf and ‘fringe’, while large snails were more abundant in areas of kelp and barrens. These patterns were found at each location sampled (i.e. eight intertidal and two subtidal rocky reefs) and at all times of sampling, across each environment. This study highlighted the consistent influence of biogenically structured habitats on the distribution, abundance and size-structure of

  5. Isolation, characterization, and extra-embryonic secretion of the Xenopus laevis embryonic epidermal lectin, XEEL.

    PubMed

    Nagata, Saburo

    2005-03-01

    The Xenopus laevis embryonic epidermal lectin (XEEL) is a novel member of a group of lectins including mammalian intelectins, frog oocyte cortical granule lectins, and plasma lectins in lower vertebrates and ascidians. We isolated the XEEL protein from the extract of tailbud embryos by affinity chromatography on a galactose-Sepharose column. The XEEL protein is a homohexamer of 43-kDa N-glycosylated peptide subunits linked by disulfide bonds. It requires Ca(2+) for saccharide binding and shows a higher affinity to pentoses than hexoses and disaccharides. HEK-293T cells transfected with an expression vector containing the XEEL cDNA secrete into the culture medium the recombinant XEEL (rXEEL) that is similar to the purified XEEL in its molecular nature and saccharide-binding properties. Substitution of Asn-192 to Gln removed the N-linked carbohydrate and inhibited secretion of rXEEL but did not abolish the activity to bind to galactose-Sepharose. The embryo's XEEL content, as estimated by western blot analyses, increases during neurula/tailbud stages and declines after 1 week postfertilization. Immunofluorescence and immuno-electron microscopic analyses showed localization of the XEEL protein in a typical secretory granule pathway of nonciliated epidermal cells. When tailbud embryos were cultured in the standard medium, XEEL was accumulated in the medium, indicating secretion of XEEL into the environmental water. The rate of XEEL secretion greatly increased at around the hatching stage and stayed at a high level during the first week after hatching. XEEL may have a role in innate immunity to protect embryos and larvae against pathogenic microorganisms in the environmental water.

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

    PubMed Central

    Mueller, Benjamin; Vermeij, Mark J.A.; van der Geest, Harm H.G.

    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. PMID:26664799

  7. In vivo antithrombotic properties of a heparin from the oocyte test cells of the sea squirt Styela plicata(Chordata-Tunicata).

    PubMed

    Cardilo-Reis, L; Cavalcante, M C M; Silveira, C B M; Pavão, M S G

    2006-11-01

    In the ascidian Styela plicata, the oocytes are surrounded by two types of accessory cells named follicle cells and test cells. A heparin-like substance with an anticoagulant activity equivalent to 10% of mammalian heparin and about 5% as potent as the mammalian counterpart for the inhibition of thrombin by antithrombin was isolated from the oocyte test cells. In the present study, we compared the antithrombotic and hemorrhagic effects of sea squirt oocyte test cell heparin with those of porcine heparin in rat models of venous thrombosis and blood loss. Intravenous administration of the oocyte test cell heparin to Wistar rats (both sexes, weighing approximately 300 g, N = 4 in each group) at a dose of 5.0 mg/kg body weight, which produced a 1.8-fold increase in plasma activated partial thromboplastin time, inhibited thrombosis by 45 +/- 13.5% (mean +/- SD) without any bleeding effect. The same dose of porcine heparin inhibited thrombosis by 100 +/- 1.4%, but produced a blood loss three times greater than that of the saline-treated control. However, 10-fold reduction of the dose of porcine heparin to 0.5 mg/kg body weight, which produced a 5-fold increase in plasma-activated partial thromboplastin time, inhibited thrombosis by 70 +/- 13% without any bleeding effect. The antithrombotic properties of a new heparin isolated from test cells of the sea squirt S. plicata, reported here for the first time, indicate that, although sea squirt oocyte test cell heparin was a poor anticoagulant compared to porcine heparin, it had a significant antithrombotic effect without causing bleeding.

  8. Widespread occurrence of an intranuclear bacterial parasite in vent and seep bathymodiolin mussels.

    PubMed

    Zielinski, Frank U; Pernthaler, Annelie; Duperron, Sébastien; Raggi, Luciana; Giere, Olav; Borowski, Christian; Dubilier, Nicole

    2009-05-01

    Many parasitic bacteria live in the cytoplasm of multicellular animals, but only a few are known to regularly invade their nuclei. In this study, we describe the novel bacterial parasite "Candidatus Endonucleobacter bathymodioli" that invades the nuclei of deep-sea bathymodiolin mussels from hydrothermal vents and cold seeps. Bathymodiolin mussels are well known for their symbiotic associations with sulfur- and methane-oxidizing bacteria. In contrast, the parasitic bacteria of vent and seep animals have received little attention despite their potential importance for deep-sea ecosystems. We first discovered the intranuclear parasite "Ca. E. bathymodioli" in Bathymodiolus puteoserpentis from the Logatchev hydrothermal vent field on the Mid-Atlantic Ridge. Using primers and probes specific to "Ca. E. bathymodioli" we found this intranuclear parasite in at least six other bathymodiolin species from vents and seeps around the world. Fluorescence in situ hybridization and transmission electron microscopy analyses of the developmental cycle of "Ca. E. bathymodioli" showed that the infection of a nucleus begins with a single rod-shaped bacterium which grows to an unseptated filament of up to 20 microm length and then divides repeatedly until the nucleus is filled with up to 80,000 bacteria. The greatly swollen nucleus destroys its host cell and the bacteria are released after the nuclear membrane bursts. Intriguingly, the only nuclei that were never infected by "Ca. E. bathymodioli" were those of the gill bacteriocytes. These cells contain the symbiotic sulfur- and methane-oxidizing bacteria, suggesting that the mussel symbionts can protect their host nuclei against the parasite. Phylogenetic analyses showed that the "Ca. E. bathymodioli" belongs to a monophyletic clade of Gammaproteobacteria associated with marine metazoans as diverse as sponges, corals, bivalves, gastropods, echinoderms, ascidians and fish. We hypothesize that many of the sequences from this clade

  9. Chordate betagamma-crystallins and the evolutionary developmental biology of the vertebrate lens.

    PubMed

    Riyahi, Kumars; Shimeld, Sebastian M

    2007-07-01

    Several animal lineages, including the vertebrates, have evolved sophisticated eyes with lenses that refract light to generate an image. The nearest invertebrate relatives of the vertebrates, such as the ascidians (sea squirts) and amphioxus, have only basic light detecting organs, leading to the widely-held view that the vertebrate lens is an innovation that evolved in early vertebrates. From an embryological perspective the lens is different from the rest of the eye, in that the eye is primarily of neural origin while the lens derives from a non-neural ectodermal placode which invaginates into the developing eye. How such an organ could have evolved has attracted much speculation. Recently, however, molecular developmental studies of sea squirts have started to suggest a possible evolutionary origin for the lens. First, studies of the Pax, Six, Eya and other gene families have indicated that sea squirts have areas of non-neural ectoderm homologous to placodes, suggesting an origin for the embryological characteristics of the lens. Second, the evolution and regulation of the betagamma-crystallins has been studied. These form one of the key crystallin gene families responsible for the transparency of the lens, and regulatory conservation between the betagamma-crystallin gene in the sea squirt Ciona intestinalis and the vertebrate visual system has been experimentally demonstrated. These data, together with knowledge of the morphological, physiological and gene expression similarities between the C. intestinalis ocellus and vertebrate retina, have led us to propose a hypothesis for the evolution of the vertebrate lens and integrated vertebrate eye via the co-option and combination of ancient gene regulatory networks; one controlling morphogenetic aspects of lens development and one controlling the expression of a gene family responsible for the biophysical properties of the lens, with the components of the retina having evolved from an ancestral photoreceptive organ

  10. Larval and metamorphic development of the foregut and proboscis in the caenogastropod Marsenina (Lamellaria) stearnsii.

    PubMed

    Page, L R

    2002-05-01

    The specialized, postmetamorphic feeding structures of predatory caenogastropods evolved by changes to an ancestral caenogastropod developmental program that generated a planktotrophic larval stage followed by a herbivorous postmetamorphic stage. As part of a program of comparative studies aimed at reconstructing these developmental changes, I studied the development of the postmetamorphic feeding system of Marsenina stearnsii using histological sections for light microscopy and scanning and transmission electron microscopy. The feeding system of this species has two very different designs during ontogeny. The larval system uses ciliary effectors to capture and ingest microalgae, whereas the juvenile/adult system includes a proboscis, jaws, and radular apparatus for predation on ascidian zooids. The postmetamorphic foregut begins to develop during the early larval phase, but the anlagen does not interfere with larval feeding because it develops as an increasingly elaborate outpocketing from the ventral wall of the larval esophagus. At metamorphosis, an opening is created in the anterior tip of the prospective, postmetamorphic buccal cavity and the margins of this opening anneal with the metamorphically remodeled lips of the larval mouth. This process exposes the jaws, which differentiate within the buccal cavity prior to metamorphosis. As a working hypothesis, I suggest that rupture of the buccal cavity to the outside at metamorphosis was selected as a mechanism to allow precocious development of jaws in species where jaws enhanced feeding performance by young juveniles. The larval esophagus of M. stearnsii appears to be completely destroyed at metamorphosis. Larval esophageal cells have distinctive apical characteristics (cilia, blebbed microvilli, stacks of lamellae within the glycocalyx) and no cells having this signature persist through metamorphosis. Development of the proboscis and proboscis sac, which begins prior to metamorphosis, conforms to previous

  11. Identification and characterization of the lamprey IRF gene.

    PubMed

    Pang, Yue; Liu, Shuang; Zheng, Zhen; Liu, Xin; Li, Qingwei

    2015-04-01

    Interferon regulatory factors (IRFs) are named for their ability to bind to and regulate interferon genes when an organism becomes infected with a virus. Numerous studies have revealed the versatile and critical functions of IRFs. In this study, an IRF gene from Lampetra japonica was identified and analyzed using bioinformatic methods. The L. japonica IRF (Lj-IRF) shares high sequence homology with other vertebrate IRFs but low sequence homology with an ascidian IRF-like protein. We also used recombinant Lj-IRF protein (rLj-IRF) to immunize New Zealand rabbits to prepare specific anti-rLj-IRF polyclonal antibodies. Enzyme-linked immunosorbent assays (ELISAs) and Western blotting assays were performed to detect the valence and specificity of the antibody. FACS analysis revealed that the Lj-IRF protein was expressed in approximately 21.14% of leukocytes and 9.60% of supraneural body cells in L. japonica, with immunofluorescence staining indicating a cytoplasmic location. The immunohistochemistry results demonstrated that IRF is distributed in the epithelial cells of the heart, supraneural body, kidneys and gills but is not detectable in intestinals or oral gland tissues. However, the expression of IRF was upregulated in lamprey intestinal tissues upon stimulation with the rLj-HMGB1 protein. Lj-IRF gene expression levels were higher in the rLj-HMGB1-stimulated group than the control group, and the expression level of Lj-IRF was significantly increased in the intestines as determined by quantitative real-time PCR. These results provide a foundation for studying the origin and evolution of the innate immune system in lampreys.

  12. Factors influencing the study of peroxidase-generated iodine species and implications for thyroglobulin synthesis.

    PubMed

    Kessler, Jack; Obinger, Christian; Eales, Geoff

    2008-07-01

    A key issue in the mechanism of thyroglobulin (Tg) iodination by thyroperoxidase (TPO) is whether a TPO-bound iodine intermediate directly iodinates Tg-incorporated tyrosines (specific iodination) or whether reactive iodine species released from TPO effectuate Tg iodination (nonspecific iodination). We addressed these alternatives by (a) determining the aqueous equilibria of the iodine species potentially involved in the kinetic studies of TPO-mediated iodination, and (b) reviewing the structure of the substrate channel in mammalian peroxidases. Redox-potentiometric analysis of aqueous iodine combined with integrated mathematical modelling demonstrates that I2 reacts with water to form several iodine species including hypoiodious acid (HOI). The HOI/I2 ratio depends on time, iodide concentration, buffering agents, and pH varying dramatically from pH 4 to 7.4. These factors may confound the use of Michaelis-Menten kinetics to determine the mechanism of TPO-catalyzed iodination since both I2 and HOI iodinate tyrosine but with different specificities and reaction rates. Consequently there is as yet no conclusive kinetic evidence that iodination occurs via formation of a TPO-bound iodinated intermediate. Furthermore, knowledge of TPO structure, gained from X-ray crystallographic studies indicates that access of Tg-bound tyrosyl groups to the active site of TPO is not possible. Thus the emerging conclusion is that the mechanism of Tg iodination is nonspecific. This is consistent with the occurrence of thyroid hormone formation in prevertebrate ascidians which exhibit TPO-like activity but lack the Tg gene.

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

    PubMed Central

    Kudryavtsev, Denis; Makarieva, Tatyana; Utkina, Natalia; Santalova, Elena; Kryukova, Elena; Methfessel, Christoph; Tsetlin, Victor; Stonik, Valentin; Kasheverov, Igor

    2014-01-01

    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. PMID:24686559

  14. Nimbus (BgI): an active non-LTR retrotransposon of the Schistosoma mansoni snail host Biomphalaria glabrata.

    PubMed

    Raghavan, Nithya; Tettelin, Hervé; Miller, André; Hostetler, Jessica; Tallon, Luke; Knight, Matty

    2007-10-01

    The freshwater snail Biomphalaria glabrata is closely associated with the transmission of human schistosomiasis. An ecologically sound method has been proposed to control schistosomiasis using genetically modified snails to displace endemic, susceptible ones. To assess the viability of this form of biological control, studies towards understanding the molecular makeup of the snail relative to the presence of endogenous mobile genetic elements are being undertaken since they can be exploited for genetic transformation studies. We previously cloned a 1.95kb BamHI fragment in B. glabrata (BGR2) with sequence similarity to the human long interspersed nuclear element (LINE or L1). A contiguous, full-length sequence corresponding to BGR2, hereafter-named nimbus (BgI), has been identified from a B. glabrata bacterial artificial chromosome (BAC) library. Sequence analysis of the 65,764bp BAC insert contained one full-length, complete nimbus (BgI) element (element I), two full-length elements (elements II and III) containing deletions and flanked by target site duplications and 10 truncated copies. The intact nimbus (BgI) contained two open-reading frames (ORFs 1 and 2) encoding the characteristic hallmark domains found in non-long terminal repeat retrotransposons belonging to the I-clade; a nucleic acid binding protein in ORF1 and an apurinic/apyrimidinic endonuclease, reverse transcriptase and RNase H in ORF2. Phylogenetic analysis revealed that nimbus (BgI) is closely related to Drosophila (I factor), mosquito Aedes aegypti (MosquI) and chordate ascidian Ciona intestinalis (CiI) retrotransposons. Nimbus (BgI) represents the first complete mobile element characterised from a mollusk that appears to be transcriptionally active and is widely distributed in snails of the neotropics and the Old World.

  15. Predation limits spread of Didemnum vexillum into natural habitats from refuges on anthropogenic structures.

    PubMed

    Forrest, Barrie M; Fletcher, Lauren M; Atalah, Javier; Piola, Richard F; Hopkins, Grant A

    2013-01-01

    Non-indigenous species can dominate fouling assemblages on artificial structures in marine environments; however, the extent to which infected structures act as reservoirs for subsequent spread to natural habitats is poorly understood. Didemnum vexillum is one of few colonial ascidian species that is widely reported to be highly invasive in natural ecosystems, but which in New Zealand proliferates only on suspended structures. Experimental work revealed that D. vexillum established equally well on suspended artificial and natural substrata, and was able to overgrow suspended settlement plates that were completely covered in other cosmopolitan fouling species. Fragmentation led to a level of D. vexillum cover that was significantly greater than was achieved as a result of ambient larval recruitment. The species failed to establish following fragment transplants onto seabed cobbles and into beds of macroalgae. The establishment success of D. vexillum was greatest in summer compared with autumn, and on the underside of experimental settlement plates that were suspended off the seabed to avoid benthic predators. Where benthic predation pressure was reduced by caging, D. vexillum establishment success was broadly comparable to suspended treatments; by contrast, the species did not establish on the face-up aspect of uncaged plates. This study provides compelling evidence that benthic predation was a key mechanism that prevented D. vexillum's establishment in the cobble habitats of the study region. The widespread occurrence of D. vexillum on suspended anthropogenic structures is consistent with evidence for other sessile invertebrates that such habitats provide a refuge from benthic predation. For invasive species generally, anthropogenic structures are likely to be most important as propagule reservoirs for spread to natural habitats in situations where predation and other mechanisms do not limit their subsequent proliferation.

  16. On the Origin and Evolution of Vertebrate Olfactory Receptor Genes: Comparative Genome Analysis Among 23 Chordate Species

    PubMed Central

    2009-01-01

    Olfaction is a primitive sense in organisms. Both vertebrates and insects have receptors for detecting odor molecules in the environment, but the evolutionary origins of these genes are different. Among studied vertebrates, mammals have ∼1,000 olfactory receptor (OR) genes, whereas teleost fishes have much smaller (∼100) numbers of OR genes. To investigate the origin and evolution of vertebrate OR genes, I attempted to determine near-complete OR gene repertoires by searching whole-genome sequences of 14 nonmammalian chordates, including cephalochordates (amphioxus), urochordates (ascidian and larvacean), and vertebrates (sea lamprey, elephant shark, five teleost fishes, frog, lizard, and chicken), followed by a large-scale phylogenetic analysis in conjunction with mammalian OR genes identified from nine species. This analysis showed that the amphioxus has >30 vertebrate-type OR genes though it lacks distinctive olfactory organs, whereas all OR genes appear to have been lost in the urochordate lineage. Some groups of genes (θ, κ, and λ) that are phylogenetically nested within vertebrate OR genes showed few gene gains and losses, which is in sharp contrast to the evolutionary pattern of OR genes, suggesting that they are actually non-OR genes. Moreover, the analysis demonstrated a great difference in OR gene repertoires between aquatic and terrestrial vertebrates, reflecting the necessity for the detection of water-soluble and airborne odorants, respectively. However, a minor group (β) of genes that are atypically present in both aquatic and terrestrial vertebrates was also found. These findings should provide a critical foundation for further physiological, behavioral, and evolutionary studies of olfaction in various organisms. PMID:20333175

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

    SciTech Connect

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

    2010-05-15

    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-17beta, 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{sup -5}, 10{sup -4} and 10{sup -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 17beta-hydroxysteroid dehydrogenase (17beta-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 17beta-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

  18. Are "universal" DNA primers really universal?

    PubMed

    Sharma, Pranay; Kobayashi, Tsuyoshi

    2014-11-01

    "Universal" DNA primers LCO 1490 and HCO 2198 were originally designed from three coding and six anticoding strands by comparing highly conserved regions of mitochondrial cytochrome c oxidase subunit I (COI) genes across 15 taxa. These primers have been successful in amplifying a 710-bp fragment of highly conserved regions of the COI gene for more than 80 invertebrate species from 11 phyla. In the present study, 130,843 variations were reviewed in the primer region of mitochondrial molecular markers by comparing 725 COI sequences from the kingdom Animalia. It was found that, for 177 invertebrate species, the forward primer (LCO 1490) showed only four conserved regions, compared to 12 in the original study. For ascidians, fungi and vertebrates, it showed approximately 50 % conserved regions, dropping to one conserved region for echinoderms. However, the reverse primer (HCO 2198) was highly conserved across 725 COI primer sequences. A similar pattern was observed in amino acid distributions. There was a significant difference in the means of base pair differences from the level of family, genus and species for LCO 1490 [analysis of variance (ANOVA), F 6,188 = 8.193, P < 0.001] and at the level of genus and species for HCO 2198 (ANOVA, F 6,77 = 2.538, P < 0.027). We conclude that, at different taxonomic levels, it is possible to design forward primers from reference sequences belonging to the level of order (maximum 5 bp differences), family (maximum 6 bp differences) or genus (maximum 1 bp difference). Reverse primers can be designed from the level of family (maximum 5 bp differences) or genus (maximum 2 bp differences).

  19. Environmental Evolution of a Small Antarctic Fjord Through the Recent Past

    NASA Astrophysics Data System (ADS)

    Hass, H. C.; Wölfl, A. C.; Wittenberg, N.; Betzler, C.; Kuhn, G.

    2014-12-01

    Rapid regional warming at an increasing pace ever since the end of the Little Ice Age (c. AD 1900) causes significant change in the coastal marine environments of the West Antarctic Peninsula and beyond. A comprehensive set of hydroacoustic ground-discrimination data (RoxAnn GDX) was gathered to develop a high resolution characterization of the seafloor habitats in the Potter Cove, King George Island, a small fjord with a retreating former tidewater glacier at its head. Sediment samples and underwater video footage are used for ground truthing. Seven habitat zones are distinguished. These include the shallow high-energy wave zone exposing unvegetated rocks to the low-energy deeper basins characterized by muddy sediments and the typical biota including ophiuroids, ascidians, sponges, sea pens. The results allow to subdivide the Potter Cove into a "dynamic zone" (DZ) with rocks and mixed fine sediments covering the inner cove, a large transition zone that we call the "subrecent zone" (SZ) buried under fine meltwater sediments and the "quasi persistent zone" (QPZ) that reveals more mature conditions in many aspects further downfjord. These zones represent development stages resulting from the increasing distance to and decreasing influence of the glacier front. The DZ is trailing directly behind the retreating glacier front. As long as there is strong discharge of sediment-loaded meltwater the DZ transitions into the SZ after a period of time (under recent conditions: decades) which itself transitions into the QPZ after centuries. We assume that during the Medieval Warm Period (c. AD 800-1350) the glacier terminus was at or even behind its present position. Until the maximum of the Little Ice Age the glacier advanced to form a prominent moraine complex. Ever since the glacier retreated at increasing speed to its recent position. If the warming trend continues the glacier will retreat further away from the fjord head and the QPZ will likely cover the entire fjord after

  20. Predation Limits Spread of Didemnum vexillum into Natural Habitats from Refuges on Anthropogenic Structures

    PubMed Central

    Forrest, Barrie M.; Fletcher, Lauren M.; Atalah, Javier; Piola, Richard F.; Hopkins, Grant A.

    2013-01-01

    Non-indigenous species can dominate fouling assemblages on artificial structures in marine environments; however, the extent to which infected structures act as reservoirs for subsequent spread to natural habitats is poorly understood. Didemnum vexillum is one of few colonial ascidian species that is widely reported to be highly invasive in natural ecosystems, but which in New Zealand proliferates only on suspended structures. Experimental work revealed that D. vexillum established equally well on suspended artificial and natural substrata, and was able to overgrow suspended settlement plates that were completely covered in other cosmopolitan fouling species. Fragmentation led to a level of D. vexillum cover that was significantly greater than was achieved as a result of ambient larval recruitment. The species failed to establish following fragment transplants onto seabed cobbles and into beds of macroalgae. The establishment success of D. vexillum was greatest in summer compared with autumn, and on the underside of experimental settlement plates that were suspended off the seabed to avoid benthic predators. Where benthic predation pressure was reduced by caging, D. vexillum establishment success was broadly comparable to suspended treatments; by contrast, the species did not establish on the face-up aspect of uncaged plates. This study provides compelling evidence that benthic predation was a key mechanism that prevented D. vexillum’s establishment in the cobble habitats of the study region. The widespread occurrence of D. vexillum on suspended anthropogenic structures is consistent with evidence for other sessile invertebrates that such habitats provide a refuge from benthic predation. For invasive species generally, anthropogenic structures are likely to be most important as propagule reservoirs for spread to natural habitats in situations where predation and other mechanisms do not limit their subsequent proliferation. PMID:24349228

  1. Multiple stressors in sediments impact adjacent hard substrate habitats and across biological domains.

    PubMed

    Lawes, Jasmin C; Dafforn, Katherine A; Clark, Graeme F; Brown, Mark V; Johnston, Emma L

    2017-08-15

    Coastal systems are increasingly impacted by human activities. While the direct effects of individual contaminants have been investigated, the potential for multiple contaminants to impact adjacent hard substrate habitats is poorly understood. Sediment-bound contaminants pose a risk to water column organisms through resuspension and the fluxing of dissolved nutrients and metals. This study experimentally manipulated contaminated coastal sediments in mesocosms with additions of a common fertiliser to investigate the impact on both bacterial biofilms and macrofouling communities on nearby hard substrates. Field mesocosms were deployed sub-tidally for two weeks in a fully crossed design with two levels of metal contamination (ambient or high) and three levels of organic enrichment (ambient, low and high). Developing biofilm and macrofaunal communities were collected on acetate settlement sheets above the mesocosm sediments and censused with a combination of high-throughput sequencing (biofilm) and microscopy (macrofauna). Organic enrichment of sediments induced compositional shifts in biofilm communities, reducing their diversity, evenness and richness. Furthermore, co-occurrence networks built from microbial assemblages exposed to contaminated sediments displayed reduced connectivity compared to controls, suggesting a more stochastic assembly dynamic, where microbial interactions are reduced. Macrofouling community composition shifted in response to increased enrichment with separate and interactive effects of metals also observed for individual taxa. Specifically, antagonistic stressor interactions were observed for colonial ascidians and arborescent bryozoans; metal contamination decreased abundances of these taxa, except under high enrichment conditions. Together these micro- and macrofaunal responses indicate selection for depauperate, but contaminant-tolerant, communities and a potential breakdown in biotic connectivity through multiple stressor impacts across

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

    NASA Technical Reports Server (NTRS)

    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.

  3. Role of Recruitment Processes in Structuring Coralligenous Benthic Assemblages in the Northern Adriatic Continental Shelf.

    PubMed

    Fava, Federica; Ponti, Massimo; Abbiati, Marco

    2016-01-01

    Coralligenous biogenic reefs are among the most diverse marine habitats in the Mediterranean Sea. The northern Adriatic mesophotic coralligenous outcrops host very rich and diverse epibenthic assemblages. Several studies quantified the low temporal variability and high spatial heterogeneity of these habitats, while processes driving structuring and differentiation are still poorly understood. To shed light on these processes, temporal and spatial patterns of colonisation were investigated using travertine tiles deployed on three coralligenous outcrops, corresponding to the main typologies of benthic assemblages described in previous studies. Three years after deployment, assemblages colonising travertine tiles resembled the differentiation among sites revealed by the natural assemblages in terms of major ecological groups. Processes structuring and maintaining species diversity have been explored. Pioneer species with high reproduction rate, long distance larval dispersal and fast growth (e.g. the serpulid polychaete Spirobranchus triqueter and the bivalve Anomia ephippium), were the most abundant in the early stages of recruitment on the two outcrops further away from the coast and with lower sedimentation. Their success may vary according to larval availability and environmental conditions (e.g., sedimentation rates). At these sites early-stage lasted 10-12 months, during which even species from natural substrates began colonising tiles by settlement of planktonic propagules (e.g., encrusting calcareous Rhodophyta) and lateral encroachment (e.g., sponges and ascidians). On coastal outcrop, exposed to a higher sedimentation rates, tiles were colonised by fast-growing algal turfs. Resilience of northern Adriatic coralligenous assemblages, and maintenance of their diversity, appeared largely entrusted to asexual reproduction. Exploring the mechanisms that underlie the formation and maintenance of the species diversity is crucial to improve our understanding of

  4. Population genetics features for persistent, but transient, Botryllus schlosseri (Urochordata) congregations in a central Californian marina.

    PubMed

    Karahan, Arzu; Douek, Jacob; Paz, Guy; Rinkevich, Baruch

    2016-08-01

    The colonial tunicate Botryllus schlosseri is a globally distributed, invasive ascidian that has colonized the Californian coasts of the USA during the mid-late 1940s and has, since the late 1980s, spread north to Washington. This study analyzes the population genetic characteristics of transient populations residing at the Elkhorn Yacht-Club (EYC), in central California (seven sessions, 1996-2008), which suffered periodic catastrophes caused by episodic fresh-water floods and a single sampling session (in the year 2001) of five West-Coast populations using the mtDNA COI gene and five microsatellite markers. EYC microsatellite results were further compared with the closely situated but persistent population of the Santa Cruz Harbor (SCH) to understand the impact on EYC population regeneration processes after the 2005-flood catastrophe. All microsatellites were highly polymorphic, revealing a large number of unique alleles at different sampling dates. Whereas pairwise θ did not reveal significant differences between the EYC time-series samplings, the overall θ was significant, as it was between all the 2001 West Coast populations. The most likely cluster number was 3 for the EYC samples whereas two K values were obtained (2 and 5) for the 2001 samples. Tajima's D and Fu's/Fs tests did not reject the null hypothesis for COI neutral evolution, except for in the EYC-2000, 2007 and two 2001 samplings. The wide geographical range of the analyses has indicated that following the EYC 2005-flood catastrophe, newcomers could have originated from neighboring populations, from deep-water colonies that may have escaped the 2005 low salinity event, or less expectedly, from far away West-Coast populations, while revealing that the SCH population is the most probable source for the EYC population.

  5. Tolerance of Sponge Assemblages to Temperature Anomalies: Resilience and Proliferation of Sponges following the 1997–8 El-Niño Southern Oscillation

    PubMed Central

    Kelmo, Francisco; Bell, James J.; Attrill, Martin J.

    2013-01-01

    Coral reefs across the world are under threat from a range of stressors, and while there has been considerable focus on the impacts of these stressors on corals, far less is known about their effect on other reef organisms. The 1997–8 El-Niño Southern Oscillation (ENSO) had notable and severe impacts on coral reefs worldwide, but not all reef organisms were negatively impacted by this large-scale event. Here we describe how the sponge fauna at Bahia, Brazil was influenced by the 1997–8 ENSO event. Sponge assemblages from three contrasting reef habitats (reef tops, walls and shallow banks) at four sites were assessed annually from 1995 to 2011. The within-habitat sponge diversity did not vary significantly across the study period; however, there was a significant increase in density in all habitats. Multivariate analyses revealed no significant difference in sponge assemblage composition (ANOSIM) between pre- and post-ENSO years for any of the habitats, suggesting that neither the 1997–8 nor any subsequent smaller ENSO events have had any measurable impact on the reef sponge assemblage. Importantly, this is in marked contrast to the results previously reported for a suite of other taxa (including corals, echinoderms, bryozoans, and ascidians), which all suffered mass mortalities as a result of the ENSO event. Our results suggest that of all reef taxa, sponges have the potential to be resilient to large-scale thermal stress events and we hypothesize that sponges might be less affected by projected increases in sea surface temperature compared to other major groups of reef organisms. PMID:24116109

  6. Role of Recruitment Processes in Structuring Coralligenous Benthic Assemblages in the Northern Adriatic Continental Shelf

    PubMed Central

    Abbiati, Marco

    2016-01-01

    Coralligenous biogenic reefs are among the most diverse marine habitats in the Mediterranean Sea. The northern Adriatic mesophotic coralligenous outcrops host very rich and diverse epibenthic assemblages. Several studies quantified the low temporal variability and high spatial heterogeneity of these habitats, while processes driving structuring and differentiation are still poorly understood. To shed light on these processes, temporal and spatial patterns of colonisation were investigated using travertine tiles deployed on three coralligenous outcrops, corresponding to the main typologies of benthic assemblages described in previous studies. Three years after deployment, assemblages colonising travertine tiles resembled the differentiation among sites revealed by the natural assemblages in terms of major ecological groups. Processes structuring and maintaining species diversity have been explored. Pioneer species with high reproduction rate, long distance larval dispersal and fast growth (e.g. the serpulid polychaete Spirobranchus triqueter and the bivalve Anomia ephippium), were the most abundant in the early stages of recruitment on the two outcrops further away from the coast and with lower sedimentation. Their success may vary according to larval availability and environmental conditions (e.g., sedimentation rates). At these sites early-stage lasted 10–12 months, during which even species from natural substrates began colonising tiles by settlement of planktonic propagules (e.g., encrusting calcareous Rhodophyta) and lateral encroachment (e.g., sponges and ascidians). On coastal outcrop, exposed to a higher sedimentation rates, tiles were colonised by fast-growing algal turfs. Resilience of northern Adriatic coralligenous assemblages, and maintenance of their diversity, appeared largely entrusted to asexual reproduction. Exploring the mechanisms that underlie the formation and maintenance of the species diversity is crucial to improve our understanding of

  7. Effects of regular and irregular temporal patterns of disturbance on biomass accrual and species composition of a subtidal hard-bottom assemblage

    NASA Astrophysics Data System (ADS)

    Wollgast, Susanne; Lenz, Mark; Wahl, Martin; Molis, Markus

    2008-12-01

    Assessing patterns of species distribution and abundance is important to understand the driving processes of, and predict future changes in, biodiversity. To this date, ecological studies have been mainly designed to investigate the effects of the mean magnitude of predictor variables, although ecological factors naturally vary in space and time. In a nine month long field experiment, we tested the effects of different temporal patterns (regular, lowly and highly irregular) in biomass removal (=disturbance event) on the diversity, species composition, and biomass accrual of macrobenthic assemblages grown on 15 × 15 cm2 PVC-panels. For each pattern of disturbance, disturbance events were timed at three sequences to control for possible confounding effects with recruitment patterns. Disturbance intensity was kept identical among treatments. Assemblages developed in the absence of disturbance for 3 months prior to a 150-day manipulation period, during which the biomass from 20% of the panel area was removed at each of ten disturbance events. Additional undisturbed settlement panels were deployed in the field to assess monthly recruitment rates and species succession over a one year period. Disturbance (i) reduced biomass and total species cover, (ii) changed species composition during the first half of the manipulation period significantly, and (iii) was without effect on species richness and evenness. Irregular disturbance regimes enhanced the abundance of the ascidian Ciona intestinalis, biomass accrual, and total species cover of assemblages relative to the regular disturbance regime, but had either no or only transient effects on diversity and species composition, respectively. Neither the degree of irregularity in disturbance nor the sequence of disturbance events affected any of the response variables significantly. Recruitment of species was strongly seasonal with almost only diatoms recruiting during winter, while recruitment was most intense during summer

  8. Disentangling the impacts of heat wave magnitude, duration and timing on the structure and diversity of sessile marine assemblages

    PubMed Central

    Yunnie, Anna L.E.; Vance, Thomas; Widdicombe, Stephen

    2015-01-01

    Extreme climatic events, including heat waves (HWs) and severe storms, influence the structure of marine and terrestrial ecosystems. Despite growing consensus that anthropogenic climate change will increase the frequency, duration and magnitude of extreme events, current understanding of their impact on communities and ecosystems is limited. Here, we used sessile invertebrates on settlement panels as model assemblages to examine the influence of HW magnitude, duration and timing on marine biodiversity patterns. Settlement panels were deployed in a marina in southwest UK for ≥5 weeks, to allow sufficient time for colonisation and development of sessile fauna, before being subjected to simulated HWs in a mesocosm facility. Replicate panel assemblages were held at ambient sea temperature (∼17 °C), or +3 °C or +5 °C for a period of 1 or 2 weeks, before being returned to the marina for a recovery phase of 2–3 weeks. The 10-week experiment was repeated 3 times, staggered throughout summer, to examine the influence of HW timing on community impacts. Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages. With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages. The observed lack of effect may have been caused by a combination of (1) the use of relatively low magnitude, realistic heat wave treatments compared to previous studies (2), the greater resilience of mature adult sessile fauna compared to recruits and juveniles, and (3) the high thermal tolerance of the model organisms (i.e., temperate fouling species, principally bryozoans and ascidians). Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may

  9. Carbonate production and deposition in a warm-temperate macroalgal environment, Investigator Strait, South Australia

    NASA Astrophysics Data System (ADS)

    James, Noel P.; Bone, Yvonne

    2011-08-01

    The prolific macroalgal forests in shallow (< 20 m), warm-temperate, marine environments off southern Yorke Peninsula, South Australia have two carbonate-producing habitats, 1) upward-facing, exposed rock surfaces beneath large phaeophytes, and 2) concealed rock surfaces under overhangs, on rock walls, in crevasses, and indentations that all lie behind a curtain of brown macroalgae. Exposed surfaces have three growth tiers; 1) a basal, cm-high veneer or turf of crustose corallines, geniculate corallines, and short fleshy red algae that are grazed by herbivorous gastropods, 2) an intermediate, 5-20 cm-high community of fleshy red algae, and 3) a 20-100 cm+-high canopy of large phaeophytes (especially Ecklonia, Cystophora and Xiophora) whose blades are locally encrusted with bryozoans, such as Membranipora membranacea, and spirorbids. Concealed surfaces of subvertical rock walls and cryptic habitats behind the macroalgal curtain have two tiers; 1) a cornucopia of encrusting plants and animals, especially crustose and geniculate corallines in shallow water, that give way in water depths > 4 m to numerous bryozoans (especially fenestrates), serpulid worms, numerous and diverse demosponges, ascidians, small solitary corals, epifaunal echinoids, and gastropods, and 2) a veil of macroalgae (mainly Cystophora and Ecklonia) that drapes down and shades the rock walls. Most carbonate sediment production does not come from calcareous epiphytes on the macroalgae but comes from the coralline algae and calcareous invertebrates living on the rock walls and in concealed depressions. Mollusks (gastropods and bivalves) and geniculate coralline algae with numerous lithoclasts, crustose coralline fragments, barnacle plates, serpulid worms, bryozoans, and large benthic foraminifers (especially Amphistegina) dominate the resultant gravels and sands; but there is little or no mud. This is because carbonate sediment is the result of production not only in the macrophyte factory but also in

  10. Sperm-surface ATP in boar spermatozoa is required for fertilization: relevance to sperm proteasomal function.

    PubMed

    Yi, Young-Joo; Park, Chang-Sik; Kim, Eui-Sook; Song, Eun-Sook; Jeong, Ji-Hyeon; Sutovsky, Peter

    2009-01-01

    Extracellular ATP has been implicated in a number of cellular events, including mammalian sperm function. The complement of ATP-dependent sperm proteins includes six subunits of the 26S proteasome, a multi-subunit protease specific to ubiquitinated substrate-proteins. Proteolysis of ubiquitinated proteins by the 26S proteasome is necessary for the success of mammalian fertilization, including but not limited to acrosomal exocytosis (AE) and sperm-zona pellucida (ZP) penetration. The 26S proteasome is uniquely present on the sperm acrosomal surface during mammalian, ascidian, and invertebrate fertilization. The proteasome is a multi-subunit protease complex of approximately 2 MDa composed of the 19S regulatory complex and a 20S proteolytic core. Integrity of the 19S complex is maintained by six 19S ATPase subunits (PSMC1 through PSMC6). Consequently, we hypothesized that fertilization will be blocked by the depletion of sperm-surface associated ATP (ssATP). Depletion of ssATP by the Solanum tuberosum apyrase, a 49 kDa, non-cell permeant enzyme, significantly reduced the ATP content measured by an adapted luminescence-ATP assay from which all permeabilizing agents were excluded. Addition of active apyrase to porcine in vitro fertilization (IVF) medium caused a concentration dependent reduction in the overall fertilization rate. No such outcomes were observed in control groups using heat-inactivated apyrase. Apyrase treatment altered the band pattern of 19S ATPase subunits PSMC1 (Rpt2) and PSMC4 (Rpt3) in Western blotting, suggesting that it had an effect on the integrity of the sperm proteasomal 19S complex. Apyrase only altered the proteasomal core activities slightly, since these activities are not directly dependent on external ATP. In contrast, sperm treatment with MG132, a specific inhibitor of the proteasomal core chymotrypsin-like activity, inhibited the target proteolytic activity, but also induced a compensatory elevation in proteasomal peptidyl

  11. Increasing the hydrolysis constant of the reactive site upon introduction of an engineered Cys¹⁴-Cys³⁹ bond into the ovomucoid third domain from silver pheasant.

    PubMed

    Hemmi, Hikaru; Kumazaki, Takashi; Kojima, Shuichi; Yoshida, Takuya; Ohkubo, Tadayasu; Yokosawa, Hideyoshi; Miura, Kin-Ichiro; Kobayashi, Yuji

    2011-08-01

    P14C/N39C is the disulfide variant of the ovomucoid third domain from silver pheasant (OMSVP3) introducing an engineered Cys¹⁴-Cys³⁹ bond near the reactive site on the basis of the sequence homology between OMSVP3 and ascidian trypsin inhibitor. This variant exhibits a narrower inhibitory specificity. We have examined the effects of introducing a Cys¹⁴-Cys³⁹ bond into the flexible N-terminal loop of OMSVP3 on the thermodynamics of the reactive site peptide bond hydrolysis, as well as the thermal stability of reactive site intact inhibitors. P14C/N39C can be selectively cleaved by Streptomyces griseus protease B at the reactive site of OMSVP3 to form a reactive site modified inhibitor. The conversion rate of intact to modified P14C/N39C is much faster than that for wild type under any pH condition. The pH-independent hydrolysis constant (K(hyd) °) is estimated to be approximately 5.5 for P14C/N39C, which is higher than the value of 1.6 for natural OMSVP3. The reactive site modified form of P14C/N39C is thermodynamically more stable than the intact one. Thermal denaturation experiments using intact inhibitors show that the temperature at the midpoint of unfolding at pH 2.0 is 59 °C for P14C/N39C and 58 °C for wild type. There have been no examples, except P14C/N39C, where introducing an engineered disulfide causes a significant increase in K(hyd) °, but has no effect on the thermal stability. The site-specific disulfide introduction into the flexible N-terminal loop of natural Kazal-type inhibitors would be useful to further characterize the thermodynamics of the reactive site peptide bond hydrolysis.

  12. Toxic effects of new antifouling compounds on tunicate haemocytes I. Sea-nine 211 and chlorothalonil.

    PubMed

    Cima, Francesca; Bragadin, Marcantonio; Ballarin, Loriano

    2008-01-31

    After the definitive ban on tin-based antifouling substances, new organic compounds have recently been introduced in antifouling paint formulations, as either principal or booster biocides. In most cases, previous risk assessment of these biocides has been inadequate so that their possible effects on aquatic ecosystems is a matter of great concern. We studied the effects of two new organic biocides often associated in paint formulations, Sea-Nine 211 (4,5 dichloro-2-n-octyl-4-isothiazoline-3-one) and chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), on haemocytes of the compound ascidian Botryllus schlosseri exposed for 60 min to various concentrations (from 0.1 to 10 microM) of the xenobiotics. This species had previously proved to be a good bioindicator of organotin compounds. Both compounds, at concentrations of 1 and 10 microM, altered the morphology of phagocytes, and these changes were closely related to disrupting effects on cytoskeletal components. At the same concentrations, phagocytosis, which requires cytoskeletal modifications for pseudopod formation, was severely hindered. Both compounds were able to induce apoptosis of Botryllus blood cells, probably as a consequence of severe oxidative stress related to the reported decrease of intracellular reduced glutathione (GSH) content. In the case of Sea-Nine 211, a substantial increase in intracellular Ca(2+) and a negative effect on Ca(2+)-ATPase activity may also be involved in the activation of the cell death machinery. Cytochrome-c-oxidase was also significantly inhibited by the two biocides, indicating perturbation of the mitochondrial respiratory chain. Isodynamic mixtures of Sea-Nine 211 and chlorothalonil were used to evaluate the occurrence of interactions between the two compounds. Results suggest the combined action of partial additivity when cell-spreading and cytochrome-c-oxidase activity were considered, and were indicative of antagonism in the case of the GSH depletion. On the whole, our

  13. Highlights of marine invertebrate-derived biosynthetic products: their biomedical potential and possible production by microbial associants.

    PubMed

    Radjasa, Ocky K; Vaske, Yvette M; Navarro, Gabriel; Vervoort, Hélène C; Tenney, Karen; Linington, Roger G; Crews, Phillip

    2011-11-15

    Coral reefs are among the most productive marine ecosystems and are the source of a large group of structurally unique biosynthetic products. Annual reviews of marine natural products continue to illustrate that the most prolific source of bioactive compounds consist of coral reef invertebrates-sponges, ascidians, mollusks, and bryozoans. This account examines recent milestone developments pertaining to compounds from invertebrates designated as therapeutic leads for biomedical discovery. The focus is on the secondary metabolites, their inspirational structural scaffolds and the possible role of micro-organism associants in their biosynthesis. Also important are the increasing concerns regarding the collection of reef invertebrates for the discovery process. The case examples considered here will be useful to insure that future research to unearth bioactive invertebrate-derived compounds will be carried out in a sustainable and environmentally conscious fashion. Our account begins with some observations pertaining to the natural history of these organisms. Many still believe that a serious obstacle to the ultimate development of a marine natural product isolated from coral reef invertebrates is the problem of compound supply. Recent achievements through total synthesis can now be drawn on to forcefully cast this myth aside. The tools of semisynthesis of complex natural products or insights from SAR efforts to simplify an active pharmacophore are at hand and demand discussion. Equally exciting is the prospect that invertebrate-associated micro-organisms may represent the next frontier to accelerate the development of high priority therapeutic candidates. Currently in the United States there are two FDA approved marine-derived therapeutic drugs and two others that are often cited as being marine-inspired. This record will be examined first followed by an analysis of a dozen of our favorite examples of coral reef invertebrate natural products having therapeutic

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

    PubMed Central

    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

  15. Impacts of trawling on benthic macro-fauna and -flora of the Spencer Gulf prawn fishing grounds

    NASA Astrophysics Data System (ADS)

    Svane, Ib; Hammett, Zoe; Lauer, Peter

    2009-05-01

    The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (˜10,000 m 2) and underwater stereophotography (˜4.5 m 2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994-1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus

  16. Total Synthesis, Stereochemical Revision, and Biological Reassessment of Mandelalide A: Chemical Mimicry of Intrafamily Relationships.

    PubMed

    Willwacher, Jens; Heggen, Berit; Wirtz, Conny; Thiel, Walter; Fürstner, Alois

    2015-07-13

    Mandelalide A and three congeners had recently been isolated as the supposedly highly cytotoxic principles of an ascidian collected off the South African coastline. Since these compounds are hardly available from the natural source, a concise synthesis route was developed, targeting structure 1 as the purported representation of mandelalide A. The sequence involves an iridium-catalyzed two-directional Krische allylation and a cobalt-catalyzed carbonylative epoxide opening as entry points for the preparation of the major building blocks. The final stages feature the first implementation of terminal acetylene metathesis into natural product total synthesis, which is remarkable in that this class of substrates had been beyond the reach of alkyne metathesis for decades. Synthetic 1, however, proved not to be identical with the natural product. In an attempt to clarify this issue, NMR spectra were simulated for 20 conceivable diastereomers by using DFT followed by DP4 analysis; however, this did not provide a reliable assignment either. The puzzle was ultimately solved by the preparation of three diastereomers, of which compound 6 proved identical with mandelalide A in all analytical and spectroscopic regards. As the entire "northern sector" about the tetrahydrofuran ring in 6 shows the opposite configuration of what had originally been assigned, it is highly likely that the stereostructures of the sister compounds mandelalides B-D must be corrected analogously; we propose that these natural products are accurately represented by structures 68-70. In an attempt to prove this reassignment, an entry into mandelalides C and D was sought by subjecting an advanced intermediate of the synthesis of 6 to a largely unprecedented intramolecular Morita-Baylis-Hillman reaction, which furnished the γ-lactone derivative 74 as a mixture of diastereomers. Whereas (24R)-74 was amenable to a hydroxyl-directed dihydroxylation by using OsO4 /TMEDA as the reagent, the sister

  17. Hemichordates and the Origin of Chordates

    NASA Technical Reports Server (NTRS)

    Gerhart, John; Kirschner, Marc; Lowe, Chris

    2002-01-01

    At the start of the period of the NASA grant three years ago, we had no information on the organization and development of the body axis of the hemichordate, Saccoglossus kowalevskii. Now we have substantial findings about the anteroposterior axis and dorsoventral axis, and based on this information, we have new insights about the origin of chordates from ancestral deuterostomes. We found ways to obtain and preserve large numbers of embryos and hatched juveniles. We can now collect about 40,000 embryos in the month of September, the time of S. kowalevskii spawning at Woods Hole. Excellent cDNA libraries were prepared from three developmental stages. From these libraries, we directly isolated about 30 gene ortholog sequences by screening and pcr techniques, all of these sequences of interest in the inquiry about the animal's organization and development. We also performed a mid-sized EST project (60,000 randomly picked clones, many of these arrayed). About half of these have been analyzed so far by blastx and are suitable for direct use of clones. We have obtained about 50 interesting sequences from this set. The rest still await analysis. Thus, at this time we have isolated orthologs of 80 genes that are known to be expressed in chordates in conserved domains and known to have interesting roles in chordate organization and development. The orthology of the S. kowalevskii sequences has been verified by neighbor joining and parsimony methods, with bootstrap estimates of validity. The S. kowalevskii sequences cluster with other deuterostome sequences, namely, other hemichordates, echinoderms, ascidians, amphioxus, or vertebrates, depending on what sequences are available in the database for comparison. We have used these sequences to do high quality in situ hybridization on S. kowalevskii embryos, and the results can be divided into three sections-those concerning the anteroposterior axis of S. kowalevskii in comparison to the same axis of chordates, those concerning

  18. The role of containerships as transfer mechanisms of marine biofouling species.

    PubMed

    Davidson, Ian C; Brown, Christopher W; Sytsma, Mark D; Ruiz, Gregory M

    2009-10-01

    Fouling of ships is an important historical and enduring transfer mechanism of marine nonindigenous species (NIS). Although containerships have risen to the forefront of global maritime shipping since the 1950s, few studies have directly sampled fouling communities on their submerged surfaces, and little is known about differences in the fouling characteristics among commercial ship types. Twenty-two in-service containerships at the Port of Oakland (San Francisco Bay, California) were sampled to test the hypothesis that the extent and taxonomic richness of fouling would be low on this type of ship, resulting from relatively fast speeds and short port durations. The data showed that the extent of macroorganisms (invertebrates and algae) was indeed low, especially across the large surface areas of the hull. Less than 1% of the exposed hull was colonized for all apart from one vessel. These ships had submerged surface areas of >7000 m(2), and fouling coverage on this area was estimated to be <17 m(2) per vessel, with zero biota detected on the hulls of many vessels. The outlying smaller vessel (4465 m(2)) had an estimated coverage of 90% on the hull and also differed substantially from the other ships in terms of its recent voyage history, shorter voyage range and slower speeds. Despite the low extent of fouling, taxonomic richness was high among vessels. Consistent with recent studies, a wide range of organisms were concentrated at more protected and heterogeneous (non-hull) niche areas, including rudders, stern tubes and intake gratings. Green algae and barnacles were most frequently sampled among vessels, but hydroids, bryozoans, bivalves and ascidians were also recorded. One vessel had 20 different species in its fouling assemblage, including non-native species (already established in San Francisco Bay) and mobile species that were not detected in visual surveys. In contrast to other studies, dry dock block areas did not support many organisms, despite little

  19. Highlights of marine invertebrate-derived biosynthetic products: Their biomedical potential and possible production by microbial associants

    PubMed Central

    Radjasa, Ocky K.; Vaske, Yvette M.; Navarro, Gabriel; Vervoort, Hélène C.; Tenney, Karen; Linington, Roger G.; Crews, Phillip

    2011-01-01

    Coral reefs are among the most productive marine ecosystems and are the source of a large group of structurally unique biosynthetic products. Annual reviews of marine natural products continue to illustrate that the most prolific source of bioactive compounds consist of coral reef invertebrates—sponges, ascidians, mollusks, and bryozoans. This account examines recent milestone developments pertaining to compounds from invertebrates designated as therapeutic leads for biomedical discovery. The focus is on the secondary metabolites, their inspirational structural scaffolds and the possible role of microorganism associants in their biosynthesis. Also important are the increasing concerns regarding the collection of reef invertebrates for the discovery process. The case examples considered here will be useful to insure that future research to unearth bioactive invertebrate-derived compounds will be carried out in a sustainable and environmentally conscious fashion. Our account begins with some observations pertaining to the natural history of these organisms. Many still believe that a serious obstacle to the ultimate development of a marine natural product isolated from coral reef invertebrates is the problem of compound supply. Recent achievements through total synthesis can now be drawn on to forcefully cast this myth aside. The tools of semisynthesis of complex natural products or insights from SAR efforts to simplify an active pharmacophore are at hand and demand discussion. Equally exciting is the prospect that invertebrate-associated micro-organisms may represent the next frontier to accelerate the development of high priority therapeutic candidates. Currently in the United States there are two FDA approved marine-derived therapeutic drugs and two others that are often cited as being marine-inspired. This record will be examined first followed by an analysis of a dozen of our favorite examples of coral reef invertebrate natural products having therapeutic

  20. Sperm proteasomes degrade sperm receptor on the egg zona pellucida during mammalian fertilization.

    PubMed

    Zimmerman, Shawn W; Manandhar, Gaurishankar; Yi, Young-Joo; Gupta, Satish K; Sutovsky, Miriam; Odhiambo, John F; Powell, Michael D; Miller, David J; Sutovsky, Peter

    2011-02-23

    Despite decades of research, the mechanism by which the fertilizing spermatozoon penetrates the mammalian vitelline membrane, the zona pellucida (ZP) remains one of the unexplained fundamental events of human/mammalian development. Evidence has been accumulating in support of the 26S proteasome as a candidate for echinoderm, ascidian and mammalian egg coat lysin. Monitoring ZP protein degradation by sperm during fertilization is nearly impossible because those few spermatozoa that penetrate the ZP leave behind a virtually untraceable residue of degraded proteins. We have overcome this hurdle by designing an experimentally consistent in vitro system in which live boar spermatozoa are co-incubated with ZP-proteins (ZPP) solubilized from porcine oocytes. Using this assay, mimicking sperm-egg interactions, we demonstrate that the sperm-borne proteasomes can degrade the sperm receptor protein ZPC. Upon coincubation with motile spermatozoa, the solubilized ZPP, which appear to be ubiquitinated, adhered to sperm acrosomal caps and induced acrosomal exocytosis/formation of the acrosomal shroud. The degradation of the sperm receptor protein ZPC was assessed by Western blotting band-densitometry and proteomics. A nearly identical pattern of sperm receptor degradation, evident already within the first 5 min of coincubation, was observed when the spermatozoa were replaced with the isolated, enzymatically active, sperm-derived proteasomes. ZPC degradation was blocked by proteasomal inhibitors and accelerated by ubiquitin-aldehyde(UBAL), a modified ubiquitin protein that stimulates proteasomal proteolysis. Such a degradation pattern of ZPC is consistent with in vitro fertilization studies, in which proteasomal inhibitors completely blocked fertilization, and UBAL increased fertilization and polyspermy rates. Preincubation of intact zona-enclosed ova with isolated active sperm proteasomes caused digestion, abrasions and loosening of the exposed zonae, and significantly reduced

  1. Fertilization in the sea: are the hazards of broadcast spawning avoided when free-spawned sperm fertilize retained eggs?

    PubMed Central

    Bishop, J. D. D.

    1998-01-01

    In broadcast-spawning marine animals, rapid dilution and short lifespan of sperm following release may impose severely localized patterns of mating. Partial or total failure of external fertilization due to sperm limitation appears commonplace. However, it is not clear to what extent the restrictive kinetics of fertilization in water also constrain mating in animals that release sperm but retain their eggs for fertilization.
    The compound ascidian Diplosoma listerianum liberates sperm that are dispersed to other colonies and taken in prior to internal cross-fertilization. The fertile lifespan of sperm was found to be long (half-life ca. 8 hours), and a substantial number of fertilizations occurred with 24-hour-old sperm. Fertilizations were obtained from sperm concentrations that would typically produce little or no external fertilization. In a separate experiment, a very small piece of D. listerianum (dry weight less than 2 mg) sired abundant progeny throughout a 3840 l tank. Paternity of progeny in these experiments was confirmed by molecular markers. The same markers were used to extend, to over seven weeks, the known maximum period of storage of exogenous sperm prior to fertilization in this species.
    The production of only a few thousand sperm at a time by each zooid, poor synchronization of release between zooids, and the existence of many well-spaced exhalant openings in large colonies suggest that D. listerianum is incapable of generating a dense plume of sperm, even close to the source. It is suggested that, unlike external fertilization, successful internal cross-fertilization in D. listerianum is not dependent upon the interception of a dense cloud of gametes just released by a near neighbour. It seems instead that dilute, long-lived sperm can be extracted efficiently from seawater by this suspension feeder, potentially over a period of time. This capability, and other features of the life history, make it unlikely that sperm limitation is an acute

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

    PubMed

    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.

  3. Evolutionary diversification of secondary mechanoreceptor cells in tunicata

    PubMed Central

    2013-01-01

    Background 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. Results 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. Conclusions 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

  4. Causes and consequences of hypoxia on the Western Black Sea Shelf

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; Gomoiu, Marian-Trajan; Naeher, Sebastian; Secrieru, Dan; Teaca, Adrian

    2013-04-01

    opportunistic species such as worms. Following the economic collapse of eastern European countries during the 1990s, riverine nutrient loads decreased and the ecosystem is showing signs of slow recovery, such as a decrease in the frequency and duration of hypoxic events. However, nutrient fluxes from the sediments did not decrease significantly (Friedrich et al. 2010). We observe slight recovery of the macrobenthic community structure in terms of species numbers in the Romanian pre-Danubian sector. Opportunistic species, e.g., ascidians, worms and fast growing filamentous algae are currently filling ecologic niches left by the past ecosystem collapse. References Friedrich, J., Cociasu, A., & Mee, L. D. (2010). Historical legacy of Danube River nutrient discharge and eutrophication in the North-Western Black Sea - Nutrient recycling in the shelf sediments. Danube News, 12(22), 7-9. Friedrich J., Dinkel C., Friedl G., Pimenov N., Wijsman J., Gomoiu M.T., Cociasu A., Popa L. & Wehrli B. (2002). Benthic Nutrient Cycling and Diagenetic Pathways in the North-western Black Sea. Estuarine, Coastal and Shelf Science, 54, 369-383. Jones G.A. & Gagnon A.R. (1994). Radiocarbon chronology of Black Sea sediments. Deep Sea Research Part I: Oceanographic Research Papers, 41, 531-557. Mee L.D., Friedrich J. & Gomoiu M.-T. (2005). Restoring the Black Sea in times of uncertainty. Oceanography, 18, 32-43. Oguz, T. and Gilbert, D. (2007). Abrupt transitions of the top-down controlled Black Sea pelagic ecosystem during 1960-2000: Evidence for regime-shifts under strong fishery exploitation and nutrient enrichment modulated by climate-induced variations. Deep-Sea Research I: doi:10.1016/j.dsr.200609.200010.

  5. Influence of solar activity on the development of calcareous nannofossils from a Middle Holocene costal paleo-ria (SW Portugal)

    NASA Astrophysics Data System (ADS)

    Hernández, Armand; Cachão, Mário; Trigo, Ricardo M.; Conceição Freitas, M.

    2015-04-01

    A 27 m long core was recovered from a present day flat-floored small fluvial valley, tributary of the Mira River (SW Portugal) allowing to span almost the complete Holocene sedimentary sequence directly overlaying Paleozoic schists and greywackes. A high resolution study of its micropaleontological content (Alday et al. 2006) was performed and 5 sedimentary stages were established: i) a coccolith-barren lower fluvial stage; ii) a coccolith intermittent lower estuarine stage; iii) a coccolith rich marine (ria) stage; iv) a coccolith intermittent upper estuarine/lagoonal stage and v) a coccolith-barren upper fluvial stage. The usefulness of calcareous nannofossils as natural tracers of the marine sedimentation contributing with valuable information for environmental reconstructions has been thoroughly demonstrated. Here, we present a high-resolution paleoenvironmental reconstruction from the interpreted marine (ria) section of the core, between 8.8k and 4.8k cal yr BP using most abundant calcareous nannofossils. Factor Analysis retrieved two major factors from the coccolith assemblages. Factor 1 (24% var.) is related to oceanic affinity community (e.g. Gephyrocapsa muellerae, Syracosphaera pulchra and Umbilicosphaera sibogae) whereas Factor 2 (23% var.) is linked to coastal neritic taxa (e.g. Ascidian spicules, Gephyrocapsa oceanica, Coccolithus pelagicus braarudii, Heliscosphaera carteri and Braarudosphaera bigelowii). These scores showed the existence of two episodes (8.8k to 7.4k and 5.8k to 5.2k cal yr BP) of marine colonization inside the paleoecological succession of the Holocene paleo-ria (8.8k and 4.8k cal yr BP). In order to establish the relationship between the solar activity and calcareous nannofossils sedimentation, cyclicity on the studied time series was investigated by performing spectral analysis on Factor 1 (F1) and Factor 2 (F2) scores. F1 score periodogram discloses three significant periodicities (460, 350 and 236-yrs) whereas F2 score