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Xavier Turon - One of the best experts on this subject based on the ideXlab platform.
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Turon X: The whereabouts of an ancient wanderer: global phylogeography of the solitary ascidian Styela plicata. PLoS One 2011
2016Co-Authors: Mari Carmen Pineda, Xavier TuronAbstract: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 th
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stochasticity in space persistence in time genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata
PeerJ, 2016Co-Authors: Susanna Lopezlegentil, Mari Carmen Pineda, Beatriz Lorente, Creu Palacin, Xavier TuronAbstract: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.
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stable populations in unstable habitats temporal genetic structure of the introduced ascidian Styela plicata in north carolina
Marine Biology, 2016Co-Authors: Carmen M Pineda, Rocio Perezportela, Xavier Turon, Susanna LopezlegentilAbstract:The analysis of temporal genetic variability is an essential yet largely neglected tool to unveil and predict the dynamics of introduced species. We here describe the temporal genetic structure and diversity over time of an introduced population of the ascidian Styela plicata (Lesueur, 1823) in Wilmington (North Carolina, USA, 34°08′24″N, 77°51′44″W). This population suffers important salinity and temperature changes, and in June every year we observed massive die-offs, leaving free substratum that was recolonized within a month. We sampled 12–14 individuals of S. plicata every 2 months from 2007 to 2009 (N = 196) and analyzed a mitochondrial marker (the gene cytochrome oxidase subunit I, COI) and seven nuclear microsatellites. Population genetic analyses showed similar results for both types of markers and revealed that most of the genetic variation was found within time periods. However, analyses conducted with microsatellite loci also showed weak but significant differences among time periods. Specifically, in the samplings after die-off episodes (August–November 2007 and 2008) the genetic diversity increased, the inbreeding coefficient showed prominent drops, and there was a net gain of alleles in the microsatellite loci. Taken together, our results suggest that recruits arriving from neighboring populations quickly occupied the newly available space, bringing new alleles with them. However, other shifts in genetic diversity and allele loss and gain episodes were observed in December–January and February–March 2008, respectively, and were apparently independent of die-off events. Overall, our results indicate that the investigated population is stable over time and relies on a periodic arrival of larvae from other populations, maintaining high genetic diversity and a complex interplay of allele gains and losses.
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The Whereabouts of an Ancient Wanderer: Global Phylogeography of the Solitary Ascidian Styela plicata
2013Co-Authors: Mari Carmen Pineda, Susanna López-legentil, Xavier TuronAbstract: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 th
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year round reproduction in a seasonal sea biological cycle of the introduced ascidian Styela plicata in the western mediterranean
Marine Biology, 2013Co-Authors: Carmen M Pineda, Susanna Lopezlegentil, Xavier TuronAbstract:The widely introduced ascidian Styela plicata is very common in the Western Mediterranean, an area that can act as a source for secondary introductions due to its high shipping activity. In order to understand the potential of this species to colonize new habitats, its reproductive features were assessed in the Western Mediterranean by means of monthly monitoring of two populations (Vilanova i la Geltru 41°12′53″N, 1°44′11″E; Blanes 41°40′29″N, 2°47′56″E) from January 2009 to December 2010. The reproductive activity of this species was assessed through gonad histology and a gonad index. Population size-structure was measured monthly in order to study recruitment dynamics. No clear seasonal pattern was observed, and mature gametes and recruits were present all year long. Spawning was potentially continuous, although it seemed punctuated with pulses of gamete release, particularly in spring. A prolonged reproductive period is likely to confer a competitive advantage on S. plicata in temperate seas, where most species reproduce seasonally, and may promote recurrent introductions as larvae are available for settlement on transport vectors over much of the year.
Matteo Cammarata - One of the best experts on this subject based on the ideXlab platform.
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the ascidian Styela plicata hemocytes as a potential biomarker of marine pollution in vitro effects of seawater and organic mercury
Ecotoxicology and Environmental Safety, 2017Co-Authors: Daniela Parrinello, Maria Giovanna Parisi, Daniela Piazzese, Antonio Bellante, Maria Antonietta Sanfratello, Serena Indelicato, Matteo CammarataAbstract: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.
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evaluation and comparison of trace metal accumulation in different tissues of potential bioindicator organisms macrobenthic filter feeders Styela plicata sabella spallanzanii and mytilus galloprovincialis
Environmental Toxicology and Chemistry, 2016Co-Authors: Antonio Bellante, Daniela Piazzese, Maria Giovanna Parisi, Salvatore Cataldo, Matteo CammarataAbstract:Trace metal concentrations were measured in different tissues of Sabella spallanzanii, Styela plicata, and Mytilus galloprovincialis collected in the Termini Imerese Harbor (Sicily, Italy) to evaluate the potential use of these species as bioindicators. Higher bioaccumulation factors (BAFs) were calculated in the tube of S. spallanzanii, except for As, which had a higher BAF in the branchial crown of the same species. Regarding the other species analyzed, higher BAFs were found in the digestive gland of M. galloprovincialis. An exception was Pb, which was significantly more concentrated in the branchial basket and tunic of S. plicata. The BAFs calculated in the present study show that all the species analyzed accumulate a certain amount of metals as a consequence of filter feeding mechanisms, and thus it was possible to assess the suitability of S. plicata, S. spallanzanii, and M. galloprovincialis as indicators of water quality. In particular, the tube of S. spallanzanii is an important compartment in terms of metal retention and is more suitable for the evaluation of contamination from trace elements. Environ Toxicol Chem 2016;35:3062-3070. © 2016 SETAC.
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in vitro effects of methylmercury on ascidian Styela plicata immunocyte responses
Applied Organometallic Chemistry, 2007Co-Authors: Matteo Cammarata, Maria Giovanna Parisi, Gigliola Benenati, Vincenzo Arizza, T Cillari, Daniela Piazzese, Antonio Gianguzza, Mirella Vazzana, Aiti Vizzini, Nicolo ParrinelloAbstract:This study shows that high methylmercury concentrations are cytotoxic for Styela plicata hemocytes, whereas sublethal concentrations affect immunocyte responses. Moreover, hemocytes exposed to the xenobiotic present a significantly enhanced phenoloxidase activity as revealed in the hemocyte lysate supernatant compared with the control. Although the cytotoxic activity of S. plicata hemocytes toward rabbit erythrocytes is a PO-dependent cell-target reaction due to quinone products, it was significantly decreased by suitable methylmercury concentrations in the medium. The same xenobiotic concentrations decreased the hemocyte phagocytic activity toward yeast. In both the responses cell-target contacts could be affected by methylmercury, whereas the releasing capacity appeared to be unchanged, as indicated by hemocyte PO-release in the medium. Finally, changes in hemocyte shape and spreading capacity were shown. On the basis of the present results, Styela plicata hemocyte responses could be an additional immunotoxicology test using a microplate method that reveals cell morphological changes and spreading capacity. Copyright © 2007 John Wiley & Sons, Ltd.
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phenoloxidase dependent cytotoxic mechanism in ascidian Styela plicata hemocytes active against erythrocytes and k562 tumor cells
European Journal of Cell Biology, 1997Co-Authors: Matteo Cammarata, N Parrinello, Giuseppina Candore, Calogero CarusoAbstract:The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of hemocytes with the antioxidant enzymes, superoxide dismutase and catalase rule out oxy radicals produced by the melanogenic process as responsible of erythrolysis. Such a result suggests that quinone compounds derived from the melanogenic pathway might be the cytotoxic molecules. The PO-dependent anti-RE activity was also shown in a plaque forming assay in which "morula cells", containing polyphenols and PO, were identified as cytotoxic.
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phenoloxidase characterization in vacuolar hemocytes from the solitary ascidian Styela plicata
Journal of Invertebrate Pathology, 1995Co-Authors: Vincenzo Arizza, Matteo Cammarata, Maria Cristina Tomasino, Nicolo ParrinelloAbstract:Abstract Phenoloxidase (PO) activity was shown in lysates of Styela plicata hemocytes assayed spectrophotometrically by means of l -Dopa oxidation without divalent cations. Trypsin and chymotrypsin pretreatment and preincubation with microbial lipopolysaccharides significantly activated PO, whereas laminarin or zymosan were ineffective. Soybean trypsin inhibitor, tropolone, and phenylthiourea, but not benzamidine, were inhibitors. Finally, hemocytes were separated by a discontinuous Percoll density gradient to determine which cells were active. PO activity was demonstrated, by both biochemical and cytochemical assays, in the separated fraction enriched mainly with the globular granulocytes called morula cells.
Mari Carmen Pineda - One of the best experts on this subject based on the ideXlab platform.
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Turon X: The whereabouts of an ancient wanderer: global phylogeography of the solitary ascidian Styela plicata. PLoS One 2011
2016Co-Authors: Mari Carmen Pineda, Xavier TuronAbstract: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 th
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stochasticity in space persistence in time genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata
PeerJ, 2016Co-Authors: Susanna Lopezlegentil, Mari Carmen Pineda, Beatriz Lorente, Creu Palacin, Xavier TuronAbstract: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.
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The Whereabouts of an Ancient Wanderer: Global Phylogeography of the Solitary Ascidian Styela plicata
2013Co-Authors: Mari Carmen Pineda, Susanna López-legentil, Xavier TuronAbstract: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 th
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Stress levels over time in the introduced ascidian Styela plicata: the effects of temperature and salinity variations on hsp70 gene expression
Cell Stress and Chaperones, 2012Co-Authors: Mari Carmen Pineda, Xavier Turon, Susanna López-legentilAbstract:Species distribution, abundance, and long-term survival are determined by biotic and abiotic regimes. However, little is known about the importance of these factors in species range expansion. Styela plicata is a solitary ascidian introduced all over the world by ship fouling, including salt marsh habitats, where introduced populations must tolerate high seasonal variations in temperature and salinity. To determine the seasonal stress levels in a salt marsh population of S. plicata , we quantified heat shock protein (hsp70) gene expression using quantitative real-time PCR throughout a 2-year cycle. Results showed that hsp70 expression varied over time, with higher stress levels recorded in summer and winter. Periodic conditions of high temperatures, particularly when coupled with low salinities, increased hsp70 gene expression. Mortality events observed every year around June were concurrent with sharp increases in temperature (>6°C), indicating that drastic changes in abiotic factors may overwhelm the observed stress response mechanisms. Determining the ability of introduced species to cope with stress, and the thresholds above which these mechanisms fail, is fundamental to predict the potential expansion range of introduced species and design efficient containment plans.
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the whereabouts of an ancient wanderer global phylogeography of the solitary ascidian Styela plicata
PLOS ONE, 2011Co-Authors: Mari Carmen Pineda, Susanna Lopezlegentil, Xavier TuronAbstract: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.
Susanna Lopezlegentil - One of the best experts on this subject based on the ideXlab platform.
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rapid establishment of the non indigenous ascidian Styela plicata and its associated bacteria in marinas and fishing harbors along the mediterranean coast of israel
Mediterranean Marine Science, 2017Co-Authors: Lion Novak, Susanna Lopezlegentil, Ella T Sieradzki, Noa ShenkarAbstract:Styela plicata (Lesueur, 1823) (Tunicata; Stolidobranchia; Styelidae) is a solitary ascidian with a global distribution. Until recently it had not been observed along the Mediterranean coast of Israel, but is now to be found in many harbors attached to suspended ropes and other artificial structures. In order to monitor the populations of S. plicata , we surveyed eight harbors along the Israeli Mediterranean coast. Our results show that the condition and maintenance of each harbor significantly affected the presence of S. plicata . We also characterized the microbial communities in the tunic of three individuals using 16S rRNA gene tag pyrosequencing and compared them to those in the surrounding seawater, in order to determine whether the symbiotic bacteria may contribute to the successful establishment of this ascidian species. We found 15 bacterial phyla in total, of which 14 were present in the animal hosts: 6 were present in all of the individuals and 4 in two of the individuals. Three of the 15 phyla observed were absent in the surrounding seawater. The high variability among the three hosts suggests a mechanism of horizontal transmission and may play a role in the process of invading new and less tolerant niches.
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stochasticity in space persistence in time genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata
PeerJ, 2016Co-Authors: Susanna Lopezlegentil, Mari Carmen Pineda, Beatriz Lorente, Creu Palacin, Xavier TuronAbstract: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.
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stable populations in unstable habitats temporal genetic structure of the introduced ascidian Styela plicata in north carolina
Marine Biology, 2016Co-Authors: Carmen M Pineda, Rocio Perezportela, Xavier Turon, Susanna LopezlegentilAbstract:The analysis of temporal genetic variability is an essential yet largely neglected tool to unveil and predict the dynamics of introduced species. We here describe the temporal genetic structure and diversity over time of an introduced population of the ascidian Styela plicata (Lesueur, 1823) in Wilmington (North Carolina, USA, 34°08′24″N, 77°51′44″W). This population suffers important salinity and temperature changes, and in June every year we observed massive die-offs, leaving free substratum that was recolonized within a month. We sampled 12–14 individuals of S. plicata every 2 months from 2007 to 2009 (N = 196) and analyzed a mitochondrial marker (the gene cytochrome oxidase subunit I, COI) and seven nuclear microsatellites. Population genetic analyses showed similar results for both types of markers and revealed that most of the genetic variation was found within time periods. However, analyses conducted with microsatellite loci also showed weak but significant differences among time periods. Specifically, in the samplings after die-off episodes (August–November 2007 and 2008) the genetic diversity increased, the inbreeding coefficient showed prominent drops, and there was a net gain of alleles in the microsatellite loci. Taken together, our results suggest that recruits arriving from neighboring populations quickly occupied the newly available space, bringing new alleles with them. However, other shifts in genetic diversity and allele loss and gain episodes were observed in December–January and February–March 2008, respectively, and were apparently independent of die-off events. Overall, our results indicate that the investigated population is stable over time and relies on a periodic arrival of larvae from other populations, maintaining high genetic diversity and a complex interplay of allele gains and losses.
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year round reproduction in a seasonal sea biological cycle of the introduced ascidian Styela plicata in the western mediterranean
Marine Biology, 2013Co-Authors: Carmen M Pineda, Susanna Lopezlegentil, Xavier TuronAbstract:The widely introduced ascidian Styela plicata is very common in the Western Mediterranean, an area that can act as a source for secondary introductions due to its high shipping activity. In order to understand the potential of this species to colonize new habitats, its reproductive features were assessed in the Western Mediterranean by means of monthly monitoring of two populations (Vilanova i la Geltru 41°12′53″N, 1°44′11″E; Blanes 41°40′29″N, 2°47′56″E) from January 2009 to December 2010. The reproductive activity of this species was assessed through gonad histology and a gonad index. Population size-structure was measured monthly in order to study recruitment dynamics. No clear seasonal pattern was observed, and mature gametes and recruits were present all year long. Spawning was potentially continuous, although it seemed punctuated with pulses of gamete release, particularly in spring. A prolonged reproductive period is likely to confer a competitive advantage on S. plicata in temperate seas, where most species reproduce seasonally, and may promote recurrent introductions as larvae are available for settlement on transport vectors over much of the year.
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characterization of novel microsatellite markers from the worldwide invasive ascidian Styela plicata
Conservation Genetics Resources, 2012Co-Authors: Claudio A Valerojimenez, Rocio Perezportela, Susanna LopezlegentilAbstract:Ten polymorphic microsatellites loci were isolated and characterized from the invasive ascidian Styela plicata by 454 pyrosequencing. From over a hundred potential microsatellite regions, 18 were selected for screening and 10 were retained based on amplification success and marker polymorphism in a sample of 39 individuals from Spain and the United States of America. The number of alleles per locus ranged from 3 to 10, with an average of 6.4 (±2.5 SD). None of the loci showed significant linkage disequilibrium or evidence of large allele drop out or scoring errors. Departure from Hardy–Weinberg equilibrium was observed for two loci in the Spanish population and five loci in the American population, where drastic annual shifts in population genetic structure have been observed. These markers will facilitate further studies on the genetic structure of this species at small spatial and temporal scales.
David A Raftos - One of the best experts on this subject based on the ideXlab platform.
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a second form of collagenous lectin from the tunicate Styela plicata
Comparative Biochemistry and Physiology B, 2006Co-Authors: Peter Green, Sham V Nair, Agnes Luty, Jane Radford, David A RaftosAbstract:This study characterised a 90 kDa lectin from an invertebrate chordate, the tunicate Styela plicata. One- and two-dimensional electrophoresis showed that the apparent molecular weight of this protein is maintained under both reducing and non-reducing conditions, suggesting that its native form is a monomer. The 90 kDa lectin was localised within a single type of hemocyte (morula cells), but was secreted from those cells when tunicates were challenged with the inflammatory elicitor, zymosan. Functional studies showed that the 90 kDa protein binds to galactose-based sugars in a divalent cation-dependent manner. Amino acid composition analysis and N-terminal amino acid sequencing indicated that the 90 kDa lectin is related to a previously characterised, collagenous lectin from S. plicata, splic43. However, peptide mass fingerprinting identified numerous differences between the two proteins. This suggests that the 90 kDa molecule represents a novel protein that is involved in host defence.
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A complement component C3-like protein from the tunicate, Styela plicata.
Developmental and Comparative Immunology, 2002Co-Authors: David A Raftos, R.a. Newton, Sham V Nair, Jennifer Robbins, Rodney PetersAbstract:Abstract This study identifies a complement component C3-like protein in the solitary tunicate, Styela plicata. Three different polyclonal antibodies raised against C3 molecules from two species (humans and the tunicate, Halocynthia roretzi) were used to identify the C3-like protein in S. plicata hemolymph. The C3 cross-reactive protein is a 170 kDa heterodimer composed of polypeptides (116 and 80 kDa) that have molecular weights comparable to those of C3α and C3β from other species. Amino acid sequencing and amino acid composition analysis confirmed that the C3-like protein from S. plicata is closely related to C3 from H. roretzi.
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effects of tributyltin and other metals on the phenoloxidase activating system of the tunicate Styela plicata
Aquatic Toxicology, 2001Co-Authors: Niina Tujula, Sham V Nair, Jane Radford, David A RaftosAbstract:Toxic metals, such as tributyltin (TBT), contribute substantially to anthropogenic pollution in many estuarine environments. Animals that live in those environments, particularly invertebrate filter feeders like tunicates, are likely to be exposed to substantial metal contamination. This study investigates the effects of TBT and other metals on the phenoloxidase activity of the estuarine tunicate, Styela plicata, in an effort to identify a biochemical marker of metal pollution. Hemocytes harvested from S. plicata that were exposed to tributyltin or copper in aquaria had significantly enhanced phenoloxidase activities relative to non-exposed controls. This enhanced phenoloxidase activity could be explained by an increased frequency of morula cells, which contain high levels of phenoloxidase's proenzyme, prophenoloxidase. Unlike those from tunicates exposed to metals in aquaria, the phenoloxidase activities of hemocytes incubated with tributyltin in vitro were significantly reduced when compared with hemocytes cultured without tributyltin. The ability of tributyltin to decrease phenoloxidase activity in tissue culture may reflect its known inhibitory effects on calcium-dependent signaling systems such as those involved in the exocytosis of prophenoloxidase from morula cells.
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a c type lectin from the tunicate Styela plicata that modulates cellular activity
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2001Co-Authors: Sham V Nair, Aimee Hutchinson, Monika Burandt, Robert L Raison, David A RaftosAbstract:Previous studies have identified proteins from tunicates (invertebrate members of the Phylum Chordata) that have physicochemical and functional properties similar to those of the inflammatory cytokine, interleukin 1 (IL-1). Here we characterize one of those proteins from the tunicate, Styela plicata, that can stimulate tunicate and mammalian cell proliferation, activate phagocytosis, increase interleukin 2 (IL-2) secretion by mammalian peripheral blood mononuclear cells and enhance IL-2 receptor (IL-2R) expression by mammalian EL-4.IL-2 cells. Partial amino acid sequence data showed that the S. plicata protein resembles three C-type lectins (TC14, TC14-1 and TC14-2) from a closely related tunicate species, Polyandrocarpa misakiensis. Its similarity to carbohydrate recognition domains (CRDs) from P. misakiensis lectins suggests that the S. plicata protein modulates the activities of mammalian immunocompetent cells by interacting with carbohydrate moieties of glycosylated cell surface receptors.
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Adoptive transfer of alloimmune memory in the solitary tunicate, Styela plicata
Journal of Experimental Zoology, 1996Co-Authors: David A RaftosAbstract:The role of hemocytes in histocompatibility responses of the tunicate, Styela plicata, was tested by adoptive transfer. Hemocytes were transferred to naive hosts from compatible individuals that had been presensitized to allogeneic tissue. Forty-four percent of the hosts that received presensitized hemocytes were capable of eliminating subsequent allografts more rapidly than control tunicates injected with saline, plasma, or hemocytes that had not been sensitized to the original graft donor. This adoptive transfer of alloimmune memory was specific to the presensitizing allogeneic tissue type. The transfer of hemocyte populations enriched in lymphocyte-like cells by density gradient centrifugation also specifically enhanced alloreactivity. Hemocyte fractions depleted of lymphocyte-like cells were incapable of inducing alloimmune memory. These data confirm that allograft rejection in S. plicata is a cell-mediated response involving lymphocyte-like cells. © 1996 Wiley-Liss, Inc.
