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Eric M. Thompson - One of the best experts on this subject based on the ideXlab platform.
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Viruses on the menu: The appendicularian Oikopleura Dioica efficiently removes viruses from seawater
Limnology and Oceanography, 2017Co-Authors: Janice E. Lawrence, Christofer Troedsson, Eric M. Thompson, Joachim Töpper, Elzbieta Anna Petelenz-kurdziel, Gunnar Bratbak, Aud Larsen, Jessica Louise RayAbstract:Appendicularians are planktonic marine tunicates with elaborate filter-feeding houses that can efficiently trap particles as small as 0.2 μm. While marine viruses are seldom considered outside their role in disease transmission, we conducted a controlled laboratory experiment to determine if the appendicularian Oikopleura Dioica can trap and ingest the Emiliania huxleyi virus (EhV; 160–180 nm diameter). Removal and retention of EhV during 2.5 h and overnight incubations at 15°C were measured using flow cytometry and quantitative polymerase chain reaction specific for the mcp gene of EhV. The fate of retained EhV was tested by quantifying EhV DNA in three biological compartments: house-trapping, ingestion/digestion, and defecation. Clearance rates for EhV varied from approximately 2 mL ind−1 d−1 to 50 mL ind−1 d−1, with highest rates for 4–5 d-old animals. EhV particles were cleared by O. Dioica at rates similar to those reported for larger food particles, with mean clearance rates in the 2.5 h incubations ranging from approximately 2 mL ind−1 d−1 to 50 mL ind−1 d−1. This demonstrates efficient virus removal by O. Dioica and a previously overlooked link between the microbial loop and the classical marine food web. EhV DNA was readily detectable above background levels in O. Dioica houses, gut contents, and faecal pellets, suggesting that appendicularian houses and faecal pellets may contribute to the dispersal of viruses. Furthermore, clearance of EhV and presumably other viruses by O. Dioica may be a significant sink for viruses and thus an important factor in regulating the population dynamics of viruses and their hosts.
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Oikopleura Dioica culturing made easy: A Low-Cost facility for an emerging animal model in EvoDevo
Genesis (New York N.Y. : 2000), 2014Co-Authors: Josep Martí-solans, Jeanmarie Bouquet, Eric M. Thompson, Daniel Chourrout, Alfonso Ferrández-roldán, Hector Godoy-marín, Jordi Badia-ramentol, Nuria P. Torres-aguila, Adriana Rodríguez-marí, Ricard AlbalatAbstract:Summary The genome sequencing and the development of RNAi knockdown technologies in the urochordate Oikopleura Dioica are making this organism an attractive emergent model in the field of EvoDevo. To succeed as a new animal model, however, an organism needs to be easily and affordably cultured in the laboratory. Nowadays, there are only two facilities in the world capable to indefinitely maintain Oikopleura Dioica, one in the SARS institute (Bergen, Norway) and the other in the Osaka University (Japan). Here, we describe the setup of a new facility in the University of Barcelona (Spain) in which we have modified previously published husbandry protocols to optimize the weekly production of thousands of embryos and hundreds of mature animals using the minimum amount of space, human resources, and technical equipment. This optimization includes novel protocols of cryopreservation and solid cultures for long-term maintenance of microalgal stocks—Chaetoceros calcitrans, Isochrysis sp., Rhinomonas reticulate, and Synechococcus sp.—needed for Oikopleura Dioica feeding. Our culture system maintains partially inbred lines healthy with similar characteristics to wild animals, and it is easily expandable to satisfy on demand the needs of any laboratory that may wish to use Oikopleura Dioica as a model organism. genesis 53:183–193, 2015. © 2014 Wiley Periodicals, Inc.
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Response of the pelagic tunicate appendicularian, Oikopleura Dioica to controlled simulations of a strong bloom condition: A bottom-up perspective
Limnology and Oceanography, 2012Co-Authors: Carla M. Lobón, Jeanmarie Bouquet, Eric M. Thompson, José Luis Acuña, Magnus Reeve, Aliona Novac, Christofer TroedssonAbstract:To test the hypothesis of bottom-up regulation of appendicularians under high food conditions that occur during blooms, an experiment including measurements of fecundity, hatching success, and mortality at different quantity and quality of food was performed on Oikopleura Dioica. Food level and fecundity were positively correlated. There was little effect of food on adult mortality, although higher food levels significantly decreased successful juvenile development. The positive effect of increased food concentration on fecundity was offset by a negative effect on hatching success; hence, the variance in quality and quantity of food explored in this study had little effect on the intrinsic rate of natural increase.
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Conservation and divergence of chemical defense system in the tunicate Oikopleura Dioica revealed by genome wide response to two xenobiotics.
BMC genomics, 2012Co-Authors: Fekadu Yadetie, Jeanmarie Bouquet, Eric M. Thompson, Coen Campsteijn, Stephen Butcher, Hilde Elise Førde, Odd André Karlsen, Raghu Metpally, J. Robert Manak, Anders GoksøyrAbstract:Background Animals have developed extensive mechanisms of response to xenobiotic chemical attacks. Although recent genome surveys have suggested a broad conservation of the chemical defensome across metazoans, global gene expression responses to xenobiotics have not been well investigated in most invertebrates. Here, we performed genome survey for key defensome genes in Oikopleura Dioica genome, and explored genome-wide gene expression using high density tiling arrays with over 2 million probes, in response to two model xenobiotic chemicals - the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) the pharmaceutical compound Clofibrate (Clo).
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Expansion of cyclin D and CDK1 paralogs in Oikopleura Dioica, a chordate employing diverse cell cycle variants
Molecular Biology and Evolution, 2011Co-Authors: Coen Campsteijn, Jan Inge Øvrebø, Bård Ove Karlsen, Eric M. ThompsonAbstract:Proliferative and endoreduplicative cell cycles are used to variable extents during the ontogeny of individual organisms and in different evolutionary lineages. Chordate growth and development is typically dominated by proliferative cycles, but the urochordate, Oikopleura Dioica, has systemically elaborated a number of endocycling modes to support rapid development and growth in an extraordinarily short chordate life cycle. Here, we identify the O. Dioica cyclin and cyclin-dependent kinase (CDK) complements and assess their deployment with respect to mitotic, meiotic, and endoreduplicative life cycle phases. Oikopleura Dioica’s ‘‘transcriptional’’ cyclin and CDK complements are similar to other complex invertebrates, whereas both the ‘‘cell cycle’’ cyclin and CDK complements display astonishing amplifications centered on the cyclin D, cyclin B, and CDK1 families. Somatic endocycles in O. Dioica involve downregulation of cyclins B and A, as in other endocycle model systems, but are also characterized by overlapping expression of an array of cyclin D isoforms. Amplification of the mitotic CDK1 family to five paralogs, which continue to be expressed in endocycling phases, is unexpected as suppression of CDK1 activity is central to endocycle transitions in Drosophila and mammals. This amplification is unique among metazoans, and substitutions in odCDK1 paralogs in the nearly invariant cyclin interaction PSTAIRE helix show striking parallels to those in the only other known eukaryotic CDK1 paralogs, plant CDKA and CDKB. As plant CDK1 paralogs exhibit an expanded repertoire of cyclin partners, including cyclin D, the evolutionary coexpansion of odCDK1 and odCyclin D families suggests that multiple CDK1–cyclin D complexes may modulate spatiotemporal control of kinase activity and substrate specificity in diverse cell cycle variants.
Hiroki Nishida - One of the best experts on this subject based on the ideXlab platform.
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3D reconstruction of structures of hatched larva and young juvenile of the larvacean Oikopleura Dioica using SBF-SEM.
Scientific reports, 2021Co-Authors: Hiroki Nishida, Nobuhiko Ohno, Federico Caicci, Lucia ManniAbstract:The larvacean Oikopleura Dioica is a planktonic chordate and an emerging model organism with a short life cycle of 5 days that belongs toTunicata (Urochordata), the sister clade of vertebrates. It is characterized by the rapid development of a tadpole-shaped body. Organ formation in the trunk proceeds within 7 h after the hatching of the tailbud larvae at 3 h after fertilization (hpf) and is completed at 10 hpf, giving rise to fully functional juveniles as miniature adult form. Serial block face scanning electron microscopy was used to acquire ~ 2000 serial transverse section images of a 3 hpf larva and a 10 hpf juvenile to characterize the structures and cellular composition of the trunk and organs using 3D images and movies. Germ cells were found to fuse and establish a central syncytial cell in the gonad as early as 10 hpf. Larval development gave rise to functional organs after several rounds of cell division through trunk morphogenesis. The feature would make O. Dioica ideal for analyzing cellular behaviors during morphogenetic processes using live imaging. The detailed descriptions of the larvae and juveniles provided in this study can be utilized as the start and end points of organ morphogenesis in this rapidly developing organism.
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DNA interference-mediated screening of maternal factors in the chordate Oikopleura Dioica
Scientific Reports, 2017Co-Authors: Tatsuya Omotezako, Takeshi A. Onuma, Masaki Matsuo, Hiroki NishidaAbstract:The maternal contribution to the oocyte cytoplasm plays an important role during embryogenesis because it is involved in early cell fate specification and embryonic axis establishment. However, screening projects targeting maternal factors have only been conducted in a limited number of animal models, such as nematodes, fruit flies, and zebrafish, while few maternal genes have been analysed because of difficulties encountered in inhibiting gene products already expressed in the ovaries. Therefore, simple and efficient methods for large-scale maternal screening are necessary. The appendicularian Oikopleura Dioica is a planktonic tunicate member of the chordates. Gonadal microinjection and a novel gene knockdown method, DNA interference (DNAi), have been developed for use in this animal with the aim of inhibiting gene functions during oogenesis within the gonad. In this study, we adapted these methods for large-scale maternal factor screening, and observed malformation phenotypes related to some maternal factors. Approximately 2000 (56.9%) ovary-enriched gene products were screened, of which the knockdown of seven encoding genes resulted in various abnormalities during embryonic development. Most of these were related to microtubules and cell adhesion-related proteins. We conclude that DNAi is a potentially powerful screening tool for the identification of novel maternal factors in chordates.
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Internal and external morphology of adults of the appendicularian, Oikopleura Dioica: an SEM study
Cell and Tissue Research, 2017Co-Authors: Takeshi A. Onuma, Miho Isobe, Hiroki NishidaAbstract:The appendicularian, Oikopleura Dioica , is a planktonic tunicate that retains a swimming tadpole shape throughout its life. It has relatively few cells and exhibits fast development, yet it has a basic chordate body plan. In this study, the morphology of adults was investigated using scanning electron microscopy (SEM) and fine 3D images of most organs were taken. The trunk epidermis is organized into bilateral territories secreting the house that includes the food-trapping filter. The pharynx extends ventrally and posteriorly to the gill openings and esophagus, respectively. The endostyle, with a morphologically distinct ciliated band, is embedded in the pharynx. The digestive tract showed left–right asymmetry as the connection between the pharynx and esophagus tilts leftward. The heart is located ventrally between the left stomach and the intestine and consists of a left muscular sheet and a right thin, non-muscular sheet. The brain is connected to the oral and ventral sensory organs, ciliary funnels and sensory vesicles and axons descend from it that eventually innervate the caudal ganglion. In the tail, a nerve cord with sporadically distributed neuronal somata runs along the left side of the notochord. The gonad is a single syncytium of thousands of gametes. In the ovary, an abundance of cortical membrane invaginate into the cytoplasm during oogenesis and the growing oocytes are interconnected via common cytoplasm through a ring canal. Spermatogenesis progresses synchronously within the common cytoplasm. These descriptions provide a valuable anatomical atlas for studying development and physiology using this simple organism with a chordate body plan.
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Maternal and zygotic transcriptomes in the appendicularian, Oikopleura Dioica: novel protein-encoding genes, intra-species sequence variations, and trans-spliced RNA leader
Development Genes and Evolution, 2015Co-Authors: Kai Wang, Hiroki Nishida, Tatsuya Omotezako, Kanae Kishi, Takeshi A. OnumaAbstract:RNA sequencing analysis was carried out to characterize egg and larval transcriptomes in the appendicularian, Oikopleura Dioica , a planktonic chordate, which is characterized by rapid development and short life cycle of 5 days, using a Japanese population of the organism. De novo transcriptome assembly matched with 16,423 proteins corresponding to 95.4 % of the protein-encoding genes deposited in the OikoBase, the genome database of the Norwegian population. Nucleotide and amino acid sequence identities between the Japanese and Norwegian O. Dioica were estimated to be around 91.0 and 94.8 %, respectively. We discovered 175 novel protein-encoding genes: 144 unigenes were common to both the Japanese and Norwegian populations, whereas 31 unigenes were not found in the OikoBase genome reference. Among the total 12,311 unigenes, approximately 63 % were detected in egg-stage RNAs, whereas 99 % were detected in larval stage RNAs; 3772 genes were up-regulated, and 1336 genes were down-regulated more than four-fold in the larvae. Gene ontology analyses characterized gene activities in these two developmental stages. We found a messenger RNA (mRNA) 5′ trans- spliced leader, which was observed in 40.8 % of the total unique transcripts. It showed preferential linkage to adenine at the 5′ ends of the downstream exons. Trans- splicing was observed more frequently in egg mRNAs compared with larva-specific mRNAs.
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DNA interference: DNA-induced gene silencing in the appendicularian Oikopleura Dioica.
Proceedings. Biological sciences, 2015Co-Authors: Tatsuya Omotezako, Takeshi A. Onuma, Hiroki NishidaAbstract:RNA interference is widely employed as a gene-silencing system in eukaryotes for host defence against invading nucleic acids. In response to invading double-stranded RNA (dsRNA), mRNA is degraded in sequence-specific manner. So far, however, DNA interference (DNAi) has been reported only in plants, ciliates and archaea, and has not been explored in Metazoa. Here, we demonstrate that linear double-stranded DNA promotes both sequence-specific transcription blocking and mRNA degradation in developing embryos of the appendicularian Oikopleura Dioica. Introduced polymerase chain reaction (PCR) products or linearized plasmids encoding Brachyury induced tail malformation and mRNA degradation. This malformation was also promoted by DNA fragments of the putative 5′-flanking region and intron without the coding region. PCR products encoding Zic-like1 and acetylcholine esterase also induced loss of sensory organ and muscle acetylcholinesterase activity, respectively. Co-injection of mRNA encoding EGFP and mCherry, and PCR products encoding these fluorescent proteins, induced sequence-specific decrease in the green or red fluorescence, respectively. These results suggest that O. Dioica possesses a defence system against exogenous DNA and RNA, and that DNA fragment-induced gene silencing would be mediated through transcription blocking as well as mRNA degradation. This is the first report of DNAi in Metazoa.
Christofer Troedsson - One of the best experts on this subject based on the ideXlab platform.
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Viruses on the menu: The appendicularian Oikopleura Dioica efficiently removes viruses from seawater
Limnology and Oceanography, 2017Co-Authors: Janice E. Lawrence, Christofer Troedsson, Eric M. Thompson, Joachim Töpper, Elzbieta Anna Petelenz-kurdziel, Gunnar Bratbak, Aud Larsen, Jessica Louise RayAbstract:Appendicularians are planktonic marine tunicates with elaborate filter-feeding houses that can efficiently trap particles as small as 0.2 μm. While marine viruses are seldom considered outside their role in disease transmission, we conducted a controlled laboratory experiment to determine if the appendicularian Oikopleura Dioica can trap and ingest the Emiliania huxleyi virus (EhV; 160–180 nm diameter). Removal and retention of EhV during 2.5 h and overnight incubations at 15°C were measured using flow cytometry and quantitative polymerase chain reaction specific for the mcp gene of EhV. The fate of retained EhV was tested by quantifying EhV DNA in three biological compartments: house-trapping, ingestion/digestion, and defecation. Clearance rates for EhV varied from approximately 2 mL ind−1 d−1 to 50 mL ind−1 d−1, with highest rates for 4–5 d-old animals. EhV particles were cleared by O. Dioica at rates similar to those reported for larger food particles, with mean clearance rates in the 2.5 h incubations ranging from approximately 2 mL ind−1 d−1 to 50 mL ind−1 d−1. This demonstrates efficient virus removal by O. Dioica and a previously overlooked link between the microbial loop and the classical marine food web. EhV DNA was readily detectable above background levels in O. Dioica houses, gut contents, and faecal pellets, suggesting that appendicularian houses and faecal pellets may contribute to the dispersal of viruses. Furthermore, clearance of EhV and presumably other viruses by O. Dioica may be a significant sink for viruses and thus an important factor in regulating the population dynamics of viruses and their hosts.
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Response of the pelagic tunicate appendicularian, Oikopleura Dioica to controlled simulations of a strong bloom condition: A bottom-up perspective
Limnology and Oceanography, 2012Co-Authors: Carla M. Lobón, Jeanmarie Bouquet, Eric M. Thompson, José Luis Acuña, Magnus Reeve, Aliona Novac, Christofer TroedssonAbstract:To test the hypothesis of bottom-up regulation of appendicularians under high food conditions that occur during blooms, an experiment including measurements of fecundity, hatching success, and mortality at different quantity and quality of food was performed on Oikopleura Dioica. Food level and fecundity were positively correlated. There was little effect of food on adult mortality, although higher food levels significantly decreased successful juvenile development. The positive effect of increased food concentration on fecundity was offset by a negative effect on hatching success; hence, the variance in quality and quantity of food explored in this study had little effect on the intrinsic rate of natural increase.
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Effects of ocean acidification, temperature and nutrient regimes on the appendicularian Oikopleura Dioica : a mesocosm study
Marine Biology, 2012Co-Authors: Christofer Troedsson, Jeanmarie Bouquet, Carla M. Lobón, Aliona Novac, Jens C. Nejstgaard, Sam Dupont, Sunčica Bosak, Hans Henrik Jakobsen, Nadezda Romanova, Lene M. PankokeAbstract:Increasing pCO2 is hypothesized to induce shifts in plankton communities toward smaller cells, reduced carbon export rates and increased roles of gelatinous zooplankton. Appendicularians, among the most numerous pan-global “gelatinous” zooplankton, continuously produce filter-feeding houses, shortcutting marine food webs by ingesting submicron particles, and their discarded houses contribute significantly to carbon fluxes. We present a first mesocosm-scale study on the effects of temperature, pCO2 and bloom structures on the appendicularian, Oikopleura Dioica. There were effects of temperature and nutrients on phytoplankton communities. No shifts in functional phytoplankton groups, nor changes in particle sizes/morphotypes, known to impact appendicularian feeding, were observed under manipulated pCO2 conditions. However, appendicularian abundance was positively correlated with increased pCO2, temperature and nutrient levels, consistent with hypotheses concerning gelatinous zooplankton in future oceans. This suggests appendicularians will play more important roles in marine pelagic communities and vertical carbon transport under projected ocean acidification and elevated temperature scenarios.
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regulation of filter feeding house components in response to varying food regimes in the appendicularian Oikopleura Dioica
Journal of Plankton Research, 2009Co-Authors: Christofer Troedsson, Jeanmarie Bouquet, José Luis Acuña, Ragnhild Skinnes, Karin Zech, Marc E Frischer, Eric M. ThompsonAbstract:The frequent repetitive secretion of filter-feeding houses of the tunicate, Oikopleura Dioica represents investment of a substantial proportion of total body carbon. Despite this investment, the filter-feeding strategy of pelagic tunicates has been proposed as an adaptation to oligotrophic environments. Here, we examined the capacity of 0. Dioica to modify its house renewal rate (HRR) and expression of component proteins, oikosins, as well as ingestion rates of different sized particles in response to varying food regimes. There were no significant changes in HRR (0.26 ± 0.07 SD house h -1 ) with age or food concentration throughout the life cycle. Our data suggest that the complex pattern of endoreduplicating cycles in the oikoplastic epithelium probably limits the capacity to reduce the energetic output of house replacement as a response to a limiting food environment. On the other hand, at the molecular level, there was differential regulation of component house proteins when animals were cultured in standard versus limiting food regimes. Animals pre-conditioned in each of these regimes and subsequently challenged with an identical mixture of large and small particles exhibited different retention efficiencies of larger food particles. Taken together, these results raise the possibility that a limited ability to modulate house architecture may underlie the differential particle retention efficiencies observed.
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Culture optimization for the emergent zooplanktonic model organism Oikopleura Dioica
Journal of plankton research, 2009Co-Authors: Jeanmarie Bouquet, Christofer Troedsson, Endy Spriet, Daniel Chourrout, Helen Otterå, Eric M. ThompsonAbstract:The pan-global marine appendicularian, Oikopleura Dioica, shows considerable promise as a candidate model organism for cross-disciplinary research ranging from chordate genetics and evolution to molecular ecology research. This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity. At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size. The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux. Among the short list of bona fide biological model organisms, all share the property that they are amenable to long-term maintenance in laboratory cultures. Here, we tested diet regimes, spawn densities and dilutions and seawater treatment, leading to optimization of a detailed culture protocol that permits sustainable long-term maintenance of O. Dioica, allowing continuous, uninterrupted production of source material for experimentation. The culture protocol can be quickly adapted in both coastal and inland laboratories and should promote rapid development of the many original research perspectives the animal offers.
Daniel Chourrout - One of the best experts on this subject based on the ideXlab platform.
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Evidence for a centrosome-attracting body like structure in germ-soma segregation during early development, in the urochordate Oikopleura Dioica
BMC Developmental Biology, 2018Co-Authors: Lisbeth Charlotte Olsen, Marit Flo Jensen, Ioannis Kourtesis, Henriette Busengdal, Harald Hausen, Daniel ChourroutAbstract:Background Germ cell formation has been investigated in sessile forms of tunicates. This process involves the release of a subset of maternal transcripts from the centrosome-attracting body (CAB) in the progenitor cells of the germ line. When germ-soma segregation is completed, CAB structures are missing from the newly formed primordial germ cells (PGCs). In free-swimming tunicates, knowledge about germ cell formation is lacking. In this investigation, comparative gene expression and electron microscopy studies were used to address germ cell formation in Oikopleura Dioica ( O. Dioica ). Results We found that the RNA localization pattern of pumilio ( pum1 ) is similar to the pattern described for a subset of maternal transcripts marking the posterior end of ascidian embryos. Transcripts marking the posterior end are called postplasmic or posterior-end mark (PEM) transcripts. We found no localization of vasa ( vas ) transcripts to any sub-region within the germ-line precursor cells. Expression of vas4 was detected in the newly formed PGCs. Electron microscopy studies confirmed the presence of structures with similar morphology to CAB. In the same cytoplasmic compartment, we also identified pum1 transcripts and an epitope recognized by an antibody to histone H3 phosphorylated on serine 28. Conclusions Our findings support that a CAB-like structure participates in the segregation of maternal pum1 transcripts during germ-soma separation in O. Dioica.
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Evidence for a centrosome-attracting body like structure in germ-soma segregation during early development, in the urochordate Oikopleura Dioica
BMC developmental biology, 2018Co-Authors: Lisbeth Charlotte Olsen, Marit Flo Jensen, Ioannis Kourtesis, Henriette Busengdal, Harald Hausen, Daniel ChourroutAbstract:Germ cell formation has been investigated in sessile forms of tunicates. This process involves the release of a subset of maternal transcripts from the centrosome-attracting body (CAB) in the progenitor cells of the germ line. When germ-soma segregation is completed, CAB structures are missing from the newly formed primordial germ cells (PGCs). In free-swimming tunicates, knowledge about germ cell formation is lacking. In this investigation, comparative gene expression and electron microscopy studies were used to address germ cell formation in Oikopleura Dioica (O. Dioica). We found that the RNA localization pattern of pumilio (pum1) is similar to the pattern described for a subset of maternal transcripts marking the posterior end of ascidian embryos. Transcripts marking the posterior end are called postplasmic or posterior-end mark (PEM) transcripts. We found no localization of vasa (vas) transcripts to any sub-region within the germ-line precursor cells. Expression of vas4 was detected in the newly formed PGCs. Electron microscopy studies confirmed the presence of structures with similar morphology to CAB. In the same cytoplasmic compartment, we also identified pum1 transcripts and an epitope recognized by an antibody to histone H3 phosphorylated on serine 28. Our findings support that a CAB-like structure participates in the segregation of maternal pum1 transcripts during germ-soma separation in O. Dioica.
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Oikopleura Dioica culturing made easy: A Low-Cost facility for an emerging animal model in EvoDevo
Genesis (New York N.Y. : 2000), 2014Co-Authors: Josep Martí-solans, Jeanmarie Bouquet, Eric M. Thompson, Daniel Chourrout, Alfonso Ferrández-roldán, Hector Godoy-marín, Jordi Badia-ramentol, Nuria P. Torres-aguila, Adriana Rodríguez-marí, Ricard AlbalatAbstract:Summary The genome sequencing and the development of RNAi knockdown technologies in the urochordate Oikopleura Dioica are making this organism an attractive emergent model in the field of EvoDevo. To succeed as a new animal model, however, an organism needs to be easily and affordably cultured in the laboratory. Nowadays, there are only two facilities in the world capable to indefinitely maintain Oikopleura Dioica, one in the SARS institute (Bergen, Norway) and the other in the Osaka University (Japan). Here, we describe the setup of a new facility in the University of Barcelona (Spain) in which we have modified previously published husbandry protocols to optimize the weekly production of thousands of embryos and hundreds of mature animals using the minimum amount of space, human resources, and technical equipment. This optimization includes novel protocols of cryopreservation and solid cultures for long-term maintenance of microalgal stocks—Chaetoceros calcitrans, Isochrysis sp., Rhinomonas reticulate, and Synechococcus sp.—needed for Oikopleura Dioica feeding. Our culture system maintains partially inbred lines healthy with similar characteristics to wild animals, and it is easily expandable to satisfy on demand the needs of any laboratory that may wish to use Oikopleura Dioica as a model organism. genesis 53:183–193, 2015. © 2014 Wiley Periodicals, Inc.
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Culture optimization for the emergent zooplanktonic model organism Oikopleura Dioica
Journal of plankton research, 2009Co-Authors: Jeanmarie Bouquet, Christofer Troedsson, Endy Spriet, Daniel Chourrout, Helen Otterå, Eric M. ThompsonAbstract:The pan-global marine appendicularian, Oikopleura Dioica, shows considerable promise as a candidate model organism for cross-disciplinary research ranging from chordate genetics and evolution to molecular ecology research. This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity. At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size. The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux. Among the short list of bona fide biological model organisms, all share the property that they are amenable to long-term maintenance in laboratory cultures. Here, we tested diet regimes, spawn densities and dilutions and seawater treatment, leading to optimization of a detailed culture protocol that permits sustainable long-term maintenance of O. Dioica, allowing continuous, uninterrupted production of source material for experimentation. The culture protocol can be quickly adapted in both coastal and inland laboratories and should promote rapid development of the many original research perspectives the animal offers.
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Development of the caudal nerve cord, motoneurons, and muscle innervation in the appendicularian urochordate Oikopleura Dioica.
The Journal of comparative neurology, 2007Co-Authors: Anne Mette Søviknes, Daniel Chourrout, Joel C. GloverAbstract:The development of the caudal nerve cord and muscle innervation in the appendicularian Oikopleura Dioica was assessed using differential interference contrast and confocal microscopy, phalloidin staining of actin, and in situ hybridization for the neuronal markers tubulin and choline acetyltransferase (ChAT). The caudal nerve cord first appears as a stream of tubulin mRNA-positive neurons that extends into the tail from the caudal ganglion. By this stage a few actin-rich nerve fibers course longitudinally along the cord. As the tail lengthens, the caudal nerve cord extends and becomes more fasciculated and the neurons cluster at stereotyped longitudinal positions. The number of neurons in the nerve cord reaches a relatively stable maximum of about 29. A subset of neurons in the caudal ganglion and caudal nerve cord expresses ChAT mRNA. These putative motoneurons are distributed along nearly the full extent of the tail in numbers consistent with an independent innervation of each tail muscle cell. The longitudinal series of putative motoneurons is not aligned with the muscle cells, but peripheral nerve fibers extending to the muscle cells are, indicating that motor axons grow along the cord before exiting adjacent to their peripheral target. Muscle innervation occurs roughly coincident with the onset of ChAT mRNA expression. Our results provide the first molecular identification of motoneurons and the first developmental characterization of the motor system in an appendicularian and help set the stage for gene expression studies aimed at understanding the evolution of developmental patterning in this part of the chordate central nervous system.
Joel C. Glover - One of the best experts on this subject based on the ideXlab platform.
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Developmental Characterization of Tail Movements in the Appendicularian Urochordate Oikopleura Dioica
Brain behavior and evolution, 2015Co-Authors: Orsolya Kreneisz, Joel C. GloverAbstract:Using high-speed video cinematography, we characterized kinematically the spontaneous tail movements made by the appendicularian urochordate Oikopleura Dioica. Videos of young adult (1-day-old) animals discriminated 4 cardinal movement types: bending, nodding, swimming and filtering, each of which had a characteristic signature including cyclicity, event or cycle duration, cycle frequency, cycle frequency variation, laterality, tail muscle segment coordination and episode duration. Bending exhibited a more common, unilateral form (single bending) and a rarer, bilateral form (alternating bending). Videos of developing animals showed that bending and swimming appeared in rudimentary form starting just after hatching and exhibited developmental changes in movement excursion, duration and frequency, whereas nodding and filtering appeared in the fully mature form in young adults at the time of first house production. More complex behaviors were associated with inflating, entering and exiting the house. We also assessed the influence of descending inputs by separating the tail (which contains all muscles and most likely the neural circuits that generate most motor outputs) from the head. Isolated tails spontaneously generated either bending or swimming movements in abnormally protracted episodes. This together with other observations of interactions between bending and swimming behaviors indicates the presence of several types of descending inputs that regulate the activity of the pattern generating circuitry in the tail nervous system.
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Continued Growth and Cell Proliferation Into Adulthood in the Notochord of the Appendicularian Oikopleura Dioica
The Biological bulletin, 2008Co-Authors: Anne Mette Søviknes, Joel C. GloverAbstract:The appendicularian urochordate Oikopleura Dioica retains a free-swimming chordate body plan through- out life, in contrast to ascidian urochordates, whose meta- morphosis to a sessile adult form involves the loss of chordate structures such as the notochord and dorsal nerve cord. Development to adult stages in Oikopleura involves a lengthening of the tail and notochord and an elaboration of the repertoire of tail movements. To investigate the cellular basis for this lengthening, we have used confocal micros- copy and BrdU labeling to examine the development of the Oikopleura notochord from hatching through adult stages. We show that as the notochord undergoes the typical uro- chordate transition from a stacked row of cells to a tubular structure, cell number begins to increase. Addition of new notochord cells continues into adulthood, multiplying the larval complement of 20 cells by about 8-fold by the third day of life. In parallel, the notochord lengthens by about 4-fold. BrdU incorporation and a cell-cycle marker confirm that notochord cells continue to proliferate well into adult- hood. The extensive postlarval proliferation of notochord cells, together with their arrangement in four circumferen- tially distributed longitudinal rows, presumably provides the Oikopleura tail with the necessary mechanical support for the complex movements exhibited at adult stages.
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Spatiotemporal patterns of neurogenesis in the appendicularian Oikopleura Dioica
Developmental biology, 2007Co-Authors: Anne Mette Søviknes, Joel C. GloverAbstract:Incorporation of the thymidine analog bromodeoxyuridine (BrdU) was used to assess cytogenesis in the central nervous system (CNS) of the appendicularian Oikopleura Dioica. A series of timed cumulative labelings carried out from 45 minutes (min) to 8 hours (h) after fertilization provided labeling patterns that showed when neurons and support cells residing at specific sites within the 9 h CNS became postmitotic. Throughout the CNS, which includes the cerebral ganglion, caudal ganglion and caudal nerve cord, neurogenesis occurs during an earlier time window than the genesis of support cells. Neurons are first generated at about 45 min to 1 h after fertilization in all 3 CNS regions, starting in the cerebral ganglion. Support cells are generated starting at about 2 h after fertilization. In both the cerebral ganglion and the caudal ganglion, neurons born during different time epochs settle in a specific spatial pattern, following a caudal to rostral gradient in the caudal ganglion and a more complex pattern in the cerebral ganglion. No such regional pattern was seen in the caudal nerve cord, where neurons born during different epochs were evenly distributed along the length of the cord. In the cerebral ganglion a small subpopulation of cells continued to incorporate BrdU from 8 h to at least 15 h and may represent a reserve of stem cells or progenitor cells that generate additional cells seen in the adult. The results show that this simple urochordate exhibits several vertebrate features of CNS cytogenesis, including a different timing of neurogenesis and gliogenesis (support cells being the likely candidates for glial cells in Oikopleura), gradients of neuron position according to birthdate, and a maintenance of neural cell precursors beyond embryonic and larval stages.
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Development of the caudal nerve cord, motoneurons, and muscle innervation in the appendicularian urochordate Oikopleura Dioica.
The Journal of comparative neurology, 2007Co-Authors: Anne Mette Søviknes, Daniel Chourrout, Joel C. GloverAbstract:The development of the caudal nerve cord and muscle innervation in the appendicularian Oikopleura Dioica was assessed using differential interference contrast and confocal microscopy, phalloidin staining of actin, and in situ hybridization for the neuronal markers tubulin and choline acetyltransferase (ChAT). The caudal nerve cord first appears as a stream of tubulin mRNA-positive neurons that extends into the tail from the caudal ganglion. By this stage a few actin-rich nerve fibers course longitudinally along the cord. As the tail lengthens, the caudal nerve cord extends and becomes more fasciculated and the neurons cluster at stereotyped longitudinal positions. The number of neurons in the nerve cord reaches a relatively stable maximum of about 29. A subset of neurons in the caudal ganglion and caudal nerve cord expresses ChAT mRNA. These putative motoneurons are distributed along nearly the full extent of the tail in numbers consistent with an independent innervation of each tail muscle cell. The longitudinal series of putative motoneurons is not aligned with the muscle cells, but peripheral nerve fibers extending to the muscle cells are, indicating that motor axons grow along the cord before exiting adjacent to their peripheral target. Muscle innervation occurs roughly coincident with the onset of ChAT mRNA expression. Our results provide the first molecular identification of motoneurons and the first developmental characterization of the motor system in an appendicularian and help set the stage for gene expression studies aimed at understanding the evolution of developmental patterning in this part of the chordate central nervous system.
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Development of putative GABAergic neurons in the appendicularian urochordate Oikopleura Dioica
The Journal of comparative neurology, 2005Co-Authors: Anne Mette Søviknes, Daniel Chourrout, Joel C. GloverAbstract:Studying the developing brain of urochordates can increase our understanding of brain evolution in the chordate lineage. To begin addressing regional patterns of neuronal differentiation in appendicularian urochordates, we examined the development of putative GABAergic neurons in Oikopleura Dioica using GABA immunohistochemistry and in situ hybridization for the GABA-synthesizing enzyme GAD. First, we assessed the developmental dynamics of neuron number and organization in the cerebral and caudal ganglia. We then identified and mapped the positions of putative GABAergic neurons using confocal microscopy. We found GAD mRNA-positive and GABA-immunopositive neurons in the first brain nerves and the cerebral and caudal ganglia, but not in the caudal nerve cord. In both ganglia GAD mRNA-positive and GABA-immunopositive neurons are found in the same characteristic intraganglionic locations. The differentiation of these GABAergic markers occurs first in the first brain nerves and the cerebral ganglion and then with a several-hour delay in the caudal ganglion. In all three structures GAD mRNA expression appears 2-3 hours prior to GABA expression. In general, GABA is expressed by the same number of neurons as express GAD. Several discrepancies suggest differential regulation of the GABAergic phenotype in different neurons, however. Our results show that the GABAergic phenotype has a stereotyped pattern of expression along the anteroposterior axis of the CNS. Given recent genome sequencing and developmental patterning gene studies in this species, the GABAergic neurons in O. Dioica provide a good model for assessing, at the invertebrate-vertebrate transition, the molecular mechanisms that specify the GABAergic phenotype.
