| 1. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 2. |
- Biressi, A., et al.
(författare)
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Wound healing and arm regeneration in Ophioderma longicaudum and Amphiura filiformis (Ophiuroidea, Echinodermata): comparative morphogenesis and histogenesis
- 2010
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Ingår i: Zoomorphology. - : Springer Science and Business Media LLC. - 0720-213X .- 1432-234X. ; 129:1, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- All species of the Ophiuroidea have exceptional regenerative capabilities; in particular, they can replace arms lost following traumatic or self-induced amputation. In order to reconstruct this complex phenomenon, we studied arm regeneration in two different ophiuroids, Ophioderma longicaudum (Retzius, 1805) and Amphiura filiformis O. F. Muller, 1776, which are quite distantly related. These species present contrasting regeneration and differentiation rates and differ in several ecological traits. The aim of this paper is to interpret the primary sequence of morphogenetic and histogenetic events leading to the complete reconstruction of a new arm, comparing the arm regenerative processes of these two ophiuroid species with those described in crinoids. Arm regeneration in ophiuroids is considered an epimorphic process in which new structures develop from a typical blastema formed from an accumulation of presumptive undifferentiated cells. Our results showed that although very different in some respects such as, for instance, the regeneration rate (0.17 mm/week for O. longicaudum and 0.99 mm/week for A. filiformis), morphogenetic and histogenetic aspects are surprisingly similar in both species. The regenerative process presents similar characteristics and follows a developmental scheme which can be subdivided into four phases: a repair phase, an early regenerative phase, an intermediate regenerative phase and an advanced regenerative phase. In terms of histogenesis, the regenerative events involve the development of new structures from migratory pluripotent cells, which proliferate actively, in addition in both cases there is a significant contribution from dedifferentiated cells, in particular dedifferentiating myocytes, although to varying extents. This evidence confirms the plasticity of the regenerative phenomenon in echinoderms, which can apparently follow different pathways in terms of growth and morphogenesis, but nevertheless involve both epimorphic and morphallactic contributions at the cellular level.
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| 3. |
- Burke, R. D., et al.
(författare)
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A genomic view of the sea urchin nervous system
- 2006
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Ingår i: Developmental Biology. - : Elsevier BV. - 0012-1606 .- 1095-564X. ; 300:1, s. 434-460
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Tidskriftsartikel (refereegranskat)abstract
- The sequencing of the Strongylocentrotus purpuratus genome provides a unique opportunity to investigate the function and evolution of neural genes. The neurobiology of sea urchins is of particular interest because they have a close phylogenetic relationship with chordates, yet a distinctive pentaradiate body plan and unusual neural organization. Orthologues of transcription factors that regulate neurogenesis in other animals have been identified and several are expressed in neurogenic domains before gastrulation indicating that they may operate near the top of a conserved neural gene regulatory network. A family of genes encoding voltage-gated ion channels is present but, surprisingly, genes encoding gap junction proteins (connexins and pannexins) appear to be absent. Genes required for synapse formation and function have been identified and genes for synthesis and transport of neurotransmitters are present. There is a large family of G-protein-coupled receptors, including 874 rhodopsin-type receptors, 28 metabotropic glutamate-like receptors and a remarkably expanded group of 161 secretin receptor-like proteins. Absence of cannabinoid, lysophospholipid and melanocortin receptors indicates that this group may be unique to chordates. There are at least 37 putative G-protein-coupled peptide receptors and precursors for several neuropeptides and peptide hormones have been identified, including SALMFamides, NGFFFamide, a vasotocin-like peptide, glycoprotein hormones and insulin/insulin-like growth factors. Identification of a neurotrophin-like gene and Trk receptor in sea urchin indicates that this neural signaling system is not unique to chordates. Several hundred chemoreceptor genes have been predicted using several approaches, a number similar to that for other animals. Intriguingly, genes encoding homologues of rhodopsin, Pax6 and several other key mammalian retinal transcription factors are expressed in tube feet, suggesting tube feet function as photosensory organs. Analysis of the sea urchin genome presents a unique perspective on the evolutionary history of deuterostome nervous systems and reveals new approaches to investigate the development and neurobiology of sea urchins. (c) 2006 Elsevier Inc. All rights reserved.
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| 4. |
- Cobb, Christopher S., et al.
(författare)
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Angiotensin I-converting enzyme-like activity in tissues from the Atlantic hagfish (Myxine glutinosa) and detection of immunoreactive plasma angiotensins
- 2004
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Ingår i: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. - : Elsevier BV. - 1096-4959. ; 138,:4, s. 357-364
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Tidskriftsartikel (refereegranskat)abstract
- Using a highly sensitive fluorimetric assay, significant levels of angiotensin I -converting enzyme-like activity (ACELA) were detected in a range of tissues (branchial heart, gill, kidney with associated vasculature and archinephric duct, liver, whole brain and gut) from the Atlantic hagfish (Myxine glutinosa). The highest ACELA occurred in heart and gill (1.8 and 1.5 nmol His–Leu min−1 mg protein−1, respectively). The mammalian angiotensin I-converting enzyme (ACE) inhibitor, captopril, at 10−5 M was a potent inhibitor of the ACELA found in all hagfish tissues. Radioimmunoassay showed that immunoreactive angiotensins (251.8±11.8 pM) were detectable in hagfish plasma. The validity of the assay for measurement of hagfish angiotensins was indicated by the parallelism of the angiotensin II standard curve against serially diluted hagfish plasma. Measurement of immunoreactive plasma angiotensins and detection of significant levels of ACELA in a wide range of tissues gives indirect evidence for the presence of a renin–angiotensin system in hagfishes, the earliest evolved group of craniates
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| 5. |
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| 6. |
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| 7. |
- Dahlberg, C., et al.
(författare)
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Refining the model system of central nervous system regeneration in Ciona intestinalis
- 2009
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Ingår i: PLoS One. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- Background New, practical models of central nervous system regeneration are required and should provide molecular tools and resources. We focus here on the tunicate Ciona intestinalis, which has the capacity to regenerate nerves and a complete adult central nervous system, a capacity unusual in the chordate phylum. We investigated the timing and sequence of events during nervous system regeneration in this organism. Methodology/Principal Findings We developed techniques for reproducible ablations and for imaging live cellular events in tissue explants. Based on live observations of more than 100 regenerating animals, we subdivided the regeneration process into four stages. Regeneration was functional, as shown by the sequential recovery of reflexes that established new criteria for defining regeneration rates. We used transgenic animals and labeled nucleotide analogs to describe in detail the early cellular events at the tip of the regenerating nerves and the first appearance of the new adult ganglion anlage. Conclusions/Significance The rate of regeneration was found to be negatively correlated with adult size. New neural structures were derived from the anterior and posterior nerve endings. A blastemal structure was implicated in the formation of new neural cells. This work demonstrates that Ciona intestinalis is as a useful system for studies on regeneration of the brain, brain-associated organs and nerves.
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| 8. |
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| 9. |
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| 10. |
- Fritzsch, Guido, et al.
(författare)
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PCR Survey of Xenoturbella bocki Hox Genes
- 2008
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Ingår i: JOURNAL OF EXPERIMENTAL ZOOLOGY (MOL DEV EVOL). - : Wiley. ; 310B:3, s. 278-284
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Tidskriftsartikel (refereegranskat)abstract
- Xenoturbella bocki has recently been identified as one of the most basal deuterostomes, although an even more basal phylogenetic position cannot be ruled out. Here we report on a polymerase chain reaction survey of partial Hox homeobox sequences of X. bocki. Surprisingly, we did not find evidence for more than five Hox genes, one clear labial/PG1 ortholog, one posterior gene most similar to the PG9/10 genes of Ambulacraria, and three central group genes whose precise assignment to a specific paralog group remains open. We furthermore report on a re-evaluation of the available published evidence of Hox genes in other basal deuterostomes.
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| 11. |
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| 12. |
- Hernroth, Bodil, 1951-, et al.
(författare)
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Immune suppression of the echinoderm Asterias rubens (L.) following long-term ocean acidification
- 2011
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Ingår i: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 103:3-4, s. 222-224
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Tidskriftsartikel (refereegranskat)abstract
- We compared effects of exposure to predict near-future (2100) ocean acidification (OA; pH 7.7) and normal seawater (Control; pH 8.1) on immune and stress responses in the adult sea star Asterias rubens. Analyses were made after one week and after six months of continuous exposure. Following one week exposure to acidified water, the pH of coelomic fluid was significantly reduced. Levels of the chaperon Hsp70 were elevated while key cellular players in immunity, coelomocytes. were reduced by approximately 50%. Following long-term exposure (six months) levels of Hsp70 returned to control values, whereas immunity was further impaired, evidenced by the reduced phagocytic capacity of coelomocytes and inhibited activation of p38 MAP-kinase. Such impacts of reduced seawater pH may have serious consequences for resistance to pathogens in a future acidified ocean.
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| 13. |
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| 14. |
- Johannesson, Kerstin, 1955, et al.
(författare)
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Ten years of marine evolutionary biology - challenges and achievements of a multidisciplinary research initiative
- 2023
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Ingår i: Evolutionary Applications. - : Wiley. - 1752-4571. ; 16:2, s. 530-41
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Tidskriftsartikel (refereegranskat)abstract
- The Centre for Marine Evolutionary Biology (CeMEB) at the University of Gothenburg, Sweden, was established in 2008 through a 10-year research grant of 8.7 m€ to a team of senior researchers. Today, CeMEB members have contributed >500 scientific publications, 30 PhD theses and have organised 75 meetings and courses, including 18 three-day meetings and four conferences. What are the footprints of CeMEB, and how will the centre continue to play a national and international role as an important node of marine evolutionary research? In this perspective arcticle we first look back over the 10 years of CeMEB activities and briefly survey some of the many achievements of CeMEB. We furthermore compare the initial goals, as formulated in the grant application, with what has been achieved, and discuss challenges and milestones along the way. Finally, we bring forward some general lessons that can be learnt from a research funding of this type, and we take also look ahead, discussing how CeMEB’s achievements and lessons can be used as a springboard to the future of marine evolutionary biology.
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| 15. |
- Long, S., et al.
(författare)
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Evolution of echinoderms may not have required modification of the ancestral deuterostome HOX gene cluster: first report of PG4 and PG5 Hox orthologues in echinoderms
- 2003
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Ingår i: Development Genes and Evolution. - 0949-944X. ; 213:11, s. 573-576
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Tidskriftsartikel (refereegranskat)abstract
- Is the extreme derivation of the echinoderm body plan reflected in a derived echinoderm Hox genotype? Building on previous work, we exploited the sequence conservation of the homeobox to isolate putative orthologues of several Hox genes from two asteroid echinoderms. The 5-peptide motif (LPNTK) diagnostic of PG4 Hox genes was identified immediately downstream of one of the partial homeodomains from Patiriella exigua. This constitutes the first unequivocal report of a PG4 Hox gene orthologue from an echinoderm. Subsequent screenings identified genes of both PG4 and PG4/5 in Asterias rubens. Although in echinoids only a single gene (PG4/5) occupies these two contiguous cluster positions, we conclude that the ancestral echinoderm must have had the complete deuterostome suite of medial Hox genes, including orthologues of both PG4 and PG4/5 (= PG5). The reported absence of PG4 in the HOX cluster of echinoids is therefore a derived state, and the ancestral echinoderm probably had a HOX cluster not dissimilar to that of other deuterostomes. Modification of the ancestral deuterostome Hox genotype may not have been required for evolution of the highly derived echinoderm body plan.
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| 16. |
- Olinski, Robert, et al.
(författare)
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Three insulin-relaxin-like genes in Ciona intestinalis
- 2006
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 27:11, s. 2535-2546
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Tidskriftsartikel (refereegranskat)abstract
- The Ciona intestinalis genome harbors three insulin-like genes: INS-L1, -L2 and -L3. Conserved synteny between the Ciona-human genomes predicts that Ciona INS-Ls are orthologous to the vertebrate insulin-relaxin family, but this relation cannot be inferred from molecular phylogeny. A conserved protein core with six cysteines; typical arrangement of B-, C- and A-protein domains; pro-protein maturation mode; and putative insulin receptor-binding sites were identified in Ciona INS-L proteins. ESTs used to assemble exonic sequences of INS-Ls combined with qRT-PCR analysis provided evidence that the predicted genes are expressed in the developing and adult Ciona. Our results support that Ciona INS-L1 is orthologous to the vertebrate insulin-like/relaxin genes, INS-L2 to insulin genies and INS-L3 to IGF genes. Our analysis also implies that the insulin-like/relaxin ancestor switched receptor type from tyrosine kinase- to GPCR-type, whereas insulin-IGF subfamily retained the tyrosine kinase-type of receptor. We propose that this receptor-switch occurred after the time when urochordates branched from the common chordate lineage, but before the two genome-duplications at the root of the vertebrates. (c) 2006 Elsevier Inc. All rights reserved.
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| 17. |
- Patruno, M., et al.
(författare)
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Anbmp2/4 is a new member of the transforming growth factor-beta superfamily isolated from a crinoid and involved in regeneration
- 2003
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - 0962-8452. ; 270:1522, s. 1341-1347
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Tidskriftsartikel (refereegranskat)abstract
- Invertebrates have frequently been used to help understand the complexities of regulatory gene function and evolution. The bone morphogenetic proteins (BMPs) are a highly conserved group of secreted regulatory factors that play an important part in early embryonic patterning. In the present study we have used the remarkable regenerative potential of crinoid echinoderms to explore the BMPs' site of expression in an adult developmental programme. Our results suggest that a crinoid BMP2/4 homologue is actively involved during the early stages of blastemal regeneration at a time when fundamental patterns are being established. This supports the idea of an evolutionary developmental programme where essential gene families are conserved throughout phylogeny in terms of both expression and function.
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| 18. |
- Patruno, M., et al.
(författare)
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Expression of transforming growth factor beta-like molecules in normal and regenerating arms of the crinoid Antedon mediterranea: immunocytochemical and biochemical evidence
- 2002
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Ingår i: Proceedings of the Royal Society of London Series B-Biological Sciences. - 0962-8452. ; 269:1502, s. 1741-1747
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Tidskriftsartikel (refereegranskat)abstract
- The phylum Echinodermata is well known for its extensive regenerative capabilities. Although there are substantial data now available that describe the histological and cellular bases of this phenomenon, little is known about the regulatory molecules involved. Here, we use an immunochemical approach to explore the potential role played by putative members of the transforming growth factor-beta (TGF-beta) family of secreted proteins in the arm regeneration process of the crinoid Antedon mediterranea. We show that a TGF-beta-like molecule is present in normal and regenerating arms both in a propeptide form and in a mature form. During regeneration, the expression of the mature form is increased and appears to be accompanied by the appearance of an additional isoform. Immunocytochemistry indicates that TGF-beta-like molecules are normally present in the nervous tissue and are specifically localized in both neural elements and non-neural migratory cells, mainly at the level of the brachial nerve. This pattern increases during regeneration, when the blastemal cells show a particularly striking expression of this molecule. Our data indicate that a TGF-beta-like molecule (or molecules) is normally present in the adult nervous tissues of A. mediterranea and is upregulated significantly during regeneration. We suggest that it can play an important part in the regenerative process.
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| 19. |
- Stumpp, Meike, et al.
(författare)
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Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification
- 2012
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Ingår i: Proceeding of the National Academy of Siences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 109:44, s. 18192-18197
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Tidskriftsartikel (refereegranskat)abstract
- Calcifying echinoid larvae respond to changes in seawater carbonate chemistry with reduced growth and developmental delay. To date, no information exists on how ocean acidification acts on pH homeostasis in echinoderm larvae. Understanding acid–base regulatory capacities is important because intracellular formation and maintenance of the calcium carbonate skeleton is dependent on pH homeostasis. Using H+-selective microelectrodes and the pH-sensitive fluorescent dye BCECF, we conducted in vivo measurements of extracellular and intracellular pH (pHe and pHi) in echinoderm larvae. We exposed pluteus larvae to a range of seawater CO2 conditions and demonstrated that the extracellular compartment surrounding the calcifying primary mesenchyme cells (PMCs) conforms to the surrounding seawater with respect to pH during exposure to elevated seawater pCO2. Using FITC dextran conjugates, we demonstrate that sea urchin larvae have a leaky integument. PMCs and spicules are therefore directly exposed to strong changes in pHe whenever seawater pH changes. However, measurements of pHi demonstrated that PMCs are able to fully compensate an induced intracellular acidosis. This was highly dependent on Na+ and HCO3−, suggesting a bicarbonate buffer mechanism involving secondary active Na+-dependent membrane transport proteins. We suggest that, under ocean acidification, maintained pHi enables calcification to proceed despite decreased pHe. However, this probably causes enhanced costs. Increased costs for calcification or cellular homeostasis can be one of the main factors leading to modifications in energy partitioning, which then impacts growth and, ultimately, results in increased mortality of echinoid larvae during the pelagic life stage.
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| 20. |
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| 21. |
- Bannister, R., et al.
(författare)
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Afuni, a novel transforming growth factor-β gene is involved in arm regeneration by the brittle star Amphiura filiformis
- 2005
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Ingår i: Development Genes and Evolution. - : Springer Science and Business Media LLC. - 0949-944X .- 1432-041X. ; 215:8, s. 393-401
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Tidskriftsartikel (refereegranskat)abstract
- The bone morphogenetic proteins (BMPs) are a family of the transforming growth factor-beta (TGF-beta) superfamily that perform multiple roles during vertebrate and invertebrate development. Here, we report the molecular cloning of a novel BMP from regenerating arms of the ophiuroid Amphiura filiformis. The theoretically translated amino acid sequence of this novel BMP has high similarity to that of the sea urchin BMP univin. This novel BMP has been named afuni. Whole-mount in situ hybridisation implicates afuni in arm regeneration. Expression occurs in distinct proximal and distal regions of late regenerates (3- and 5-week postablation). These sites are at different stages of regeneration, suggesting multiple roles for this gene in adult arm development. Cellular expression of this gene occurs in migratory cells within the radial water canal (RWC) of regenerating and nonregenerating arms. These migrating coelomocytes suggest a key role for the coelomic RWC as a source of the cellular material for use in arm regeneration by A. filiformis
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| 22. |
- Bannister, R., et al.
(författare)
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Coelomic expression of a novel bone morphogenetic protein in regenerating arms of the brittle star Amphiura filiformis
- 2008
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Ingår i: Development Genes and Evolution. - 0949-944X. ; 218:1, s. 33-38
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Tidskriftsartikel (refereegranskat)abstract
- The bone morphogenetic proteins (BMPs) are a family of signalling molecules involved in numerous developmental processes including cell fate determination in embryonic ectoderm of vertebrate and invertebrate species. Recently, published evidence has indicated that BMPs are involved in echinoderm adult tissue regeneration. We have cloned a novel member of the BMP2/4 subfamily from the ophiuroid echinoderm Amphiura filiformis, which we have named afBMP2/4. Whole-mount in-situ hybridisation performed on non-regenerating brittle star arms revealed that expression of afBMP2/4 is localised to the radial water canal (RWC) and that this expression is upregulated at segmental intervals along the arm. This observed expression pattern suggests a putative active role for this echinoderm BMP transcript in somatic growth and maintenance of the brittle star arm. Expression of this factor has also been observed in regenerating arms 2 weeks post-ablation, implicating the RWC as a source of cells for ophiuroid arm regeneration.
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| 23. |
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| 24. |
- Bourlat, Sarah, et al.
(författare)
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Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida
- 2006
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Ingår i: Nature. ; 444:7115, s. 85-88
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Tidskriftsartikel (refereegranskat)abstract
- Deuterostomes comprise vertebrates, the related invertebrate chordates (tunicates and cephalochordates) and three other inver- tebrate taxa: hemichordates, echinoderms and Xenoturbella1. The relationships between invertebrate and vertebrate deuterostomes are clearly important for understanding our own distant origins. Recent phylogenetic studies of chordate classes and a sea urchin have indicated that urochordates might be the closest inverte- brate sister group of vertebrates, rather than cephalochordates, as traditionally believed2–5. More remarkable is the suggestion that cephalochordates are closer to echinoderms than to vertebrates and urochordates, meaning that chordates are paraphyletic2. To study the relationships among all deuterostome groups, we have assembled an alignment of more than 35,000 homologous amino acids, including new data from a hemichordate, starfish and Xenoturbella. We have also sequenced the mitochondrial genome of Xenoturbella. We support the clades Olfactores (urochordates and vertebrates) and Ambulacraria (hemichordates and echino- derms6). Analyses using our new data, however, do not support a cephalochordate and echinoderm grouping and we conclude that chordates are monophyletic. Finally, nuclear and mitochondrial data place Xenoturbella as the sister group of the two ambulacrar- ian phyla1. As such, Xenoturbella is shown to be an independent phylum, Xenoturbellida, bringing the number of living deutero- stome phyla to four.
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| 25. |
- Bourlat, Sarah, et al.
(författare)
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Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcoding
- 2008
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Ingår i: Molecular Ecology Resources. - 1755-098X. ; 8, s. 18-22
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Tidskriftsartikel (refereegranskat)abstract
- The benthic marine worm Xenoturbella is frequently contaminated with molluscan DNA, which had earlier caused confusion resulting in a suggested bivalve relationship. In order to find the source of the contaminant, we have used molluscan sequences derived from Xenoturbella and compared them to barcodes obtained from several individuals of the nonmicroscopic molluscs sharing the same environment as Xenoturbella. Using cytochrome oxidase 1, we found the contaminating sequences to be 98% similar to the bivalve Ennucula tenuis. Using the highly variable D1-D2 region of the large ribosomal subunit in Xenoturbella, we found three distinct species of contaminating molluscs, one of which is 99% similar to the bivalve Abra nitida, one of the most abundant bivalves in the Gullmarsfjord where Xenoturbella was found, and another 99% similar to the bivalve Nucula sulcata. These data clearly show that Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship. In addition, these data suggest that Xenoturbella feeds specifically on bivalve prey from multiple species, possibly in the form of eggs and larvae.
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| 26. |
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| 27. |
- Burns, Gavin, et al.
(författare)
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Transcriptome pyrosequencing of the Antarctic brittle star Ophionotus victoriae
- 2013
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Ingår i: Marine Genomics. - : Elsevier BV. - 1874-7787. ; 9, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- Brittle stars are included within a whole range of species, which contribute to knowledge in the medically important area of tissue regeneration. All brittle stars regenerate lose limbs, but the rate at which this occurs is highly variable and species-specific. One of the slowest rates of arm regeneration reported so far is that of the Antarctic Ophionotus victoriae. Additionally, O. victoriae also has an unusual delay in the onset of regeneration of about 5. months. Both processes are of interest for the areas of regeneration biology and adaptation to cold environments. One method of understanding the details of regeneration events in brittle stars is to characterise the genes involved. In the largest transcriptome study of any ophiuroid to date, we describe the results of mRNA pyrosequencing from pooled samples of regenerating arms of O. victoriae. The sequencing reads resulted in 18,000 assembled contiguous sequences of which 19% were putatively annotated by blast sequence similarity searching. We focus on the identification of major gene families and pathways with potential relevance to the regenerative processes including the Wnt/β-catenin pathway, Hox genes, the SOX gene family and the TGF beta signalling pathways. These data significantly increase the amount of ophiuroid sequences publicly available and provide candidate transcripts for the further investigation of the unusual regenerative process in this Antarctic ophiuroid. © 2012 Elsevier B.V.
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| 28. |
- Burns,, et al.
(författare)
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Intrinsic gene expression during regeneration in arm explants of Amphiura filiformis
- 2012
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 413, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- The extensive regeneration ability of ophiuroids, particularly in relation to arm re-growth following amputation, is becoming increasingly recognized as a useful model system for understanding cellular differentiation and regeneration in a whole animal context. Amputated ophiuroid arms are referred to as explants. These are able to survive for several months in seawater and, when amputated at both ends (“double amputated”), can undergo partial regeneration at one end and wound healing at the other. As such, they present a simplified and controlled regenerating model system which can potentially provide clues as to the mechanism involved in the programming and polarity of cellular differentiation. In this first investigation of gene expression in an ophiuroid explant we used cDNA microarrays in the transcriptional profiling of the proximal, medial and distal sections of double amputated explants of the temperate brittle star Amphiura filiformis. The results demonstrated an active transcriptome with extensive differential gene expression focused at the original distal part of the arm explant where the regenerating blastema was located. The transcription profiles also revealed that expression patterns showed subtle differences in the levels of gene expression rather than the presence or absence of certain genes. The sections of arm under study were no longer attached to the whole animal and therefore reduced levels of activity of some transcripts e.g. ciboulot, a gene potentially involved in cell differentiation events such as neuronal development, suggest that transcript dosage and/or relative expression of certain gene combinations may play an important role in the progression of cellular differentiation events.
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| 29. |
- Byrne, M., et al.
(författare)
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Expression of the neuropeptide SALMFamide-1 during regeneration of the seastar radial nerve cord following arm autotomy
- 2019
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 286:1901
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Tidskriftsartikel (refereegranskat)abstract
- Arm loss through a separation at a specialized autotomy plane in echinoderms is inextricably linked to regeneration, but the link between these phenomena is poorly explored. We investigated nervous system regeneration post-autotomy in the asteriid seastar Coscinasterias muricata, focusing on the reorganization of the radial nerve cord (RNC) into the ectoneural neuroepithelium and neuropile, and the hyponeural region, using antibodies to the seastar-specific neuropeptide SALMFamide-1 (S1). Parallel changes in the associated haemal and coelomic vessels were also examined. A new arm bud appeared in 3-5 days with regeneration over three weeks. At the nerve stump and in the RNC immediately behind, the haemal sinus/hyponeural coelomic compartments enlarged into a hypertrophied space filled with migratory cells that appear to be involved in wound healing and regeneration. The haemal and coelomic compartments provided a conduit for these cells to gain rapid access to the regeneration site. An increase in the number of glia-like cells indicates the importance of these cells in regeneration. Proximal to the autotomy plane, the original RNC exhibited Wallerian-type degeneration, as seen in disorganized axons and enlarged S1-positive varicosities. The imperative to regrow lost arms quickly is reflected in the efficiency of regeneration from the autotomy plane facilitated by the rapid appearance of progenitor-like migratory cells. In parallel to its specialization for defensive arm detachment, the autotomy plane appears to be adapted to promote regeneration. This highlights the importance of examining autotomy-induced regeneration in seastars as a model system to study nervous system regeneration in deuterostomes and the mechanisms involved with the massive migration of stem-like cells to facilitate rapid recovery.
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| 30. |
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| 31. |
- Chan, Karen, et al.
(författare)
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Ocean acidification induces budding in larval sea urchins
- 2013
-
Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 160:8, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification (OA), the reduction of ocean pH due to hydration of atmospheric CO2, is known to affect growth and survival of marine invertebrate larvae. Survival and transport of vulnerable planktonic larval stages play important roles in determining population dynamics and community structures in coastal ecosystems. Here, we show that larvae of the purple urchin, Strongylocentrotus purpuratus, underwent high-frequency budding (release of blastula-like particles) when exposed to elevated pCO2 level (>700 μatm). Budding was observed in >50 % of the population and was synchronized over short periods of time (~24 h), suggesting this phenomenon may be previously overlooked. Although budding can be a mechanism through which larval echinoids asexually reproduce, here, the released buds did not develop into viable clones. OA-induced budding and the associated reduction in larval size suggest new hypotheses regarding physiological and ecological tradeoffs between short-term benefits (e.g. metabolic savings and predation escape) and long-term costs (e.g. tissue loss and delayed development) in the face of climate change.
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| 32. |
- Clark, M. S., et al.
(författare)
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Delayed arm regeneration in the Antarctic brittle star Ophionotus victoriae
- 2007
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 1:1, s. 45-53
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Tidskriftsartikel (refereegranskat)abstract
- We describe the levels of natural arm damage in the Antarctic brittle star Ophionotus victoriae and the rate of arm regeneration over the period of 1 yr, as measured in our aquarium facilities at Rothera Point, West Antarctic Peninsula. The natural incidence of arm damage in O. victoriae is high (97 % of individuals examined). The rate of regeneration was 0.44 mm wk(-1), which is slow, but within the range of data from temperate brittle stars and also in line with data from the literature showing a general trend of decreasing arm regeneration rate with temperature. The Q(10) for arm regeneration rate of 2.6 across brittle stars is within the expected biological range. However, O. victoriae arm regeneration experiences a lag phase of up to 5 mo before reproducible amounts of new tissue are produced. Such a long lag phase has not been documented for any other brittle star species and produces a range of Q(10) values from 3.6 (when compared to the slowest documented lag phase for a temperate brittle star) to exceptionally high Q(10) values of 14.9 and 15.4 (when either fastest or average regeneration times are considered for temperate brittle stars and this Antarctic species). This indicates that the initial process of arm regeneration in O. victoriae is either different to that of other brittle stars or it is dependent on factors other than the effects of temperature on enzyme-mediated biochemical reactions, such as gonadal cycles and seasonality.
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| 33. |
- Dorey, Narimane, 1986, et al.
(författare)
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Assessing physiological tipping point of sea urchin larvae exposed to a broad range of pH
- 2013
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 19:11, s. 3355-3367
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Tidskriftsartikel (refereegranskat)abstract
- Our ability to project the impact of global change on marine ecosystem is limited by our poor understanding on how to predict species sensitivity. For example, the impact of ocean acidification is highly species-specific, even in closely related taxa. The aim of this study was to test the hypothesis that the tolerance range of a given species to decreased pH corresponds to their natural range of exposure. Larvae of the green sea urchin Strongylocentrotus droebachiensis were cultured from fertilization to metamorphic competence (29days) under a wide range of pH (from pH(T)=8.0/pCO(2)approximate to 480atm to pH(T)=6.5/pCO(2)approximate to 20000atm) covering present (from pH(T) 8.7 to 7.6), projected near-future variability (from pH(T) 8.3 to 7.2) and beyond. Decreasing pH impacted all tested parameters (mortality, symmetry, growth, morphometry and respiration). Development of normal, although showing morphological plasticity, swimming larvae was possible as low as pH(T)7.0. Within that range, decreasing pH increased mortality and asymmetry and decreased body length (BL) growth rate. Larvae raised at lowered pH and with similar BL had shorter arms and a wider body. Relative to a given BL, respiration rates and stomach volume both increased with decreasing pH suggesting changes in energy budget. At the lowest pHs (pH(T)6.5), all the tested parameters were strongly negatively affected and no larva survived past 13days post fertilization. In conclusion, sea urchin larvae appeared to be highly plastic when exposed to decreased pH until a physiological tipping point at pH(T)=7.0. However, this plasticity was associated with direct (increased mortality) and indirect (decreased growth) consequences for fitness.
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| 34. |
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| 35. |
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| 36. |
- Dupont, Samuel, 1971, et al.
(författare)
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Growth or differentiation? Adaptive regeneration in the brittlestar Amphiura filiformis
- 2006
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Ingår i: The Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 209, s. 3873-3881
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Tidskriftsartikel (refereegranskat)abstract
- Amphiura filiformis is a burrowing brittlestar, which extends arms in the water column when suspension feeding. In previous studies, unexpectedly high variability was observed in regeneration rate between individuals even when experiments were performed under identical conditions. The aims of this work were to understand this variability and interpret the observed variability in terms of adaptation to sublethal predation. Our experiments on the dynamics of arm regeneration in A. filiformis revealed that the developmental program during regeneration is well adapted to its burrowing life style. We demonstrate that there is a trade-off between regeneration in length and functional recovery for feeding (differentiation index). The amount of tissue lost (length lost), which represents the quantity of tissue needed to completely regenerate an intact arm with no previous history of regeneration, determines whether the arm will invest more energy in growth and/or in differentiation, which must be a reflection of the ability to differentially regulate developmental programs during regeneration. We show that combining regeneration rate with differentiation index provides an ideal tool for the definition of a standard temporal framework for both field and laboratory studies of regeneration
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| 37. |
- Dupont, Samuel, 1971, et al.
(författare)
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Impact of near-future ocean acidification on echinoderms.
- 2010
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Ingår i: Ecotoxicology. - : Springer Science and Business Media LLC. - 1573-3017 .- 0963-9292. ; 19:3, s. 449-462
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Forskningsöversikt (refereegranskat)abstract
- As a consequence of increasing atmospheric CO(2), the world's oceans are warming and slowly becoming more acidic (ocean acidification, OA) and profound changes in marine ecosystems are certain. Calcification is one of the primary targets for studies of the impact of CO(2)-driven climate change in the oceans and one of the key marine groups most likely to be impacted by predicted climate change events are the echinoderms. Echinoderms are a vital component of the marine environment with representatives in virtually every ecosystem, where they are often keystone ecosystem engineers. This paper reviews and analyses what is known about the impact of near-future ocean acidification on echinoderms. A global analysis of the literature reveals that echinoderms are surprisingly robust to OA and that important differences in sensitivity to OA are observed between populations and species. However, this is modulated by parameters such as (1) exposure time with rare longer term experiments revealing negative impacts that are hidden in short or midterm ones; (2) bottlenecks in physiological processes and life-cycle such as stage-specific developmental phenomena that may drive the whole species responses; (3) ecological feedback transforming small scale sub lethal effects into important negative effects on fitness. We hypothesize that populations/species naturally exposed to variable environmental pH conditions may be pre-adapted to future OA highlighting the importance to understand and monitor environmental variations in order to be able to to predict sensitivity to future climate changes. More stress ecology research is needed at the frontier between ecotoxicology and ecology, going beyond standardized tests using model species in order to address multiple water quality factors (e.g. pH, temperature, toxicants) and organism health. However, available data allow us to conclude that near-future OA will have negative impact on echinoderm taxa with likely significant consequences at the ecosystem level.
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| 38. |
- Dupont, Samuel, 1971, et al.
(författare)
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Long-term and trans-life-cycle effects of exposure to ocean acidification in the green sea urchin Strongylocentrotus droebachiensis
- 2013
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 160:8, s. 1835-1843
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic CO2 emissions are acidifying the world’s oceans. A growing body of evidence demonstrates that ocean acidification can impact survival, growth, development and physiology of marine invertebrates. Here, we tested the impact of long-term (up to 16 months) and trans-life-cycle (adult, embryo/larvae and juvenile) exposure to elevated pCO2 (1,200 μatm, compared to control 400 μatm) on the green sea urchin Strongylocentrotus droebachiensis. Female fecundity was decreased 4.5-fold when acclimated to elevated pCO2 for 4 months during reproductive conditioning, while no difference was observed in females acclimated for 16 months. Moreover, adult pre-exposure for 4 months to elevated pCO2 had a direct negative impact on subsequent larval settlement success. Five to nine times fewer offspring reached the juvenile stage in cultures using gametes collected from adults previously acclimated to high pCO2 for 4 months. However, no difference in larval survival was observed when adults were pre-exposed for 16 months to elevated pCO2. pCO2 had no direct negative impact on juvenile survival except when both larvae and juveniles were raised in elevated pCO2. These negative effects on settlement success and juvenile survival can be attributed to carry-over effects from adults to larvae and from larvae to juveniles. Our results support the contention that adult sea urchins can acclimate to moderately elevated pCO2 in a matter of a few months and that carry-over effects can exacerbate the negative impact of ocean acidification on larvae and juveniles.
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| 39. |
- Dupont, Samuel, 1971, et al.
(författare)
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Near Future Ocean Acidification Increases Growth Rate of the Lecithotrophic Larvae and Juveniles of the Sea Star Crossaster papposus
- 2010
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Ingår i: Journal of Experimental Zoology Part B-Molecular and Developmental Evolution. - 1552-5007. ; 314B:5, s. 382-389
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification (OA) is believed to be a major threat for near-future marine ecosystems, and that the most sensitive organisms will be calcifying organisms and the free-living larval stages produced by most benthic marine species. In this respect, echinoderms are one of the taxa most at risk. Earlier research on the impact of near-future OA on echinoderm larval stages showed negative effects, such as a decreased growth rate, increased mortality, and developmental abnormalities. However, all the long-term studies were performed on planktotrophic larvae while alternative life-history strategies, such as nonfeeding lecithotrophy, were largely ignored. Here, we show that lecithotrophic echinoderm larvae and juveniles are positively impacted by ocean acidification. When cultured at low pH, larvae and juveniles of the sea star Crossaster papposus grow faster with no visible affects on survival or skeletogenesis. This suggests that in future oceans, lecithotrophic species may be better adapted to deal with the threat of OA compared with planktotrophic ones with potentially important consequences at the ecosystem level. For example, an increase in populations of the top predator C. papposus will likely have huge consequences for community structure. Our results also highlight the importance of taking varying life-history strategies into account when assessing the impacts of climate change, an approach that also provides insight into understanding the evolution of life-history strategies. J. Exp. Zool. (Mol. Dev. Evol) 314B:382-389, 2010. (C) 2010 Wiley-Liss, Inc.
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| 40. |
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| 41. |
- Dupont, Samuel, 1971, et al.
(författare)
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Relationship between CO2-driven changes in extracellular acid-base balance and cellular immune-response in two polar echinoderm species
- 2012
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 424-425, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic CO2 emissions are acidifying the world's oceans. A growing body of evidence demonstrates that ocean acidification can impact survival, growth, development and physiology of marine invertebrates. However, little is known on the impact of elevated pCO2 on immune-response. Here we investigate the impact of short-term (5–7 days) exposure to elevated pCO2 (1275 μatm compared to 350 μatm in the control) on extracellular pH (pHe) and cellular immune response in two polar echinoderm species, the green sea urchin Strongylocentrotus droebachiensis and the seastar Leptasterias polaris. Both species experienced extracellular acidosis following short term exposure to elevated pCO2. While this acidosis remained uncompensated within 7 days for L. polaris, pHe was fully compensated after 5 days for S. droebachiensis. For both species, coelomic fluid acidosis was associated with an increase in total coelomocyte number and a reduction in vibratile cells in S. droebachiensis. A relationship between pHe and phagocyte numbers was observed in S. droebachiensis suggesting a direct link between pHe and cellular immune-response. Further studies would require the coordinated effort of ecologists and immunologists to understand the role of elevated pCO2 on the host–pathogen interactions that are involved in the stability of ecosystems.
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| 42. |
- Dupont, Samuel, 1971, et al.
(författare)
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What meta-analysis can tell us about vulnerability of marine biodiversity to ocean acidification?
- 2010
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Ingår i: Estuarine Coastal and Shelf Science. - 0272-7714. ; 89:2, s. 182-185
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification has been proposed as a major threat for marine biodiversity. Hendriks et al. [Hendriks, I.E., Duarte, C.M., Alvarez, M., 2010. Vulnerability of marine biodiversity to ocean acidification: a meta-analysis. Estuarine, Coastal and Shelf Science, doi:10.1016/j.ecss.2009.11.022.] proposed an alternative view and suggested, based on a meta-analysis, that marine biota may be far more resistant to ocean acidification than hitherto believed. However, such a meta-analytical approach can mask more subtle features, for example differing sensitivities during the life-cycle of an organism. Using a similar metric on an echinoderm database, we show that key bottlenecks present in the life-cycle (e.g. larvae being more vulnerable than adults) and responsible for driving the whole species response may be hidden in a global meta-analysis. Our data illustrate that any ecological meta-analysis should be hypothesis driven, taking into account the complexity of biological systems, including all life-cycle stages and key biological processes. Available data allow us to conclude that near-future ocean acidification can/will have dramatic negative impact on some marine species, including echinoderms, with likely consequences at the ecosystem level. (C) 2010 Elsevier Ltd. All rights reserved.
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| 43. |
- Elphick, Maurice R., et al.
(författare)
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Molecular characterisation of SALMFamide neuropeptides in sea urchins
- 2005
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 208, s. 4273-4282
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Tidskriftsartikel (refereegranskat)abstract
- The SALMFamides are a family of neuropeptides found in species belonging to the phylum Echinodermata. Members of this family have been identified in starfish (class Asteroidea) and in sea cucumbers (class Holothuroidea) but not in other echinoderms. Our aim here was to characterise SALMFamide neuropeptides in sea urchins (class Echinoidea). Radioimmunoassays for the starfish SALMFamides S1 and S2 were used to test for related peptides in whole-body acetone extracts of the sea urchin Echinus esculentus. Fractionation of extracts using high performance liquid chromatography (HPLC) revealed several peaks of SALMFamide-like immunoreactivity, with two S2-like immunoreactive peaks (3 and 4) being the most prominent. However, peak 4 could not be purified to homogeneity and although peak 3 was purified, only a partial sequence (MRYH) could be obtained
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| 44. |
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| 45. |
- Furlong, R. F., et al.
(författare)
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A degenerate ParaHox gene cluster in a degenerate vertebrate
- 2007
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Ingår i: Molecular Biology and Evolution. - 0737-4038. ; 24:12, s. 2681-2686
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Tidskriftsartikel (refereegranskat)abstract
- The ParaHox genes consist of 3 homeobox gene families, Gsx, Xlox, and Cdx, all of which have fundamental roles in development. Xlox (known as IPF1 or PDX1 in vertebrates), for example, is crucial for development of the vertebrate pancreas and is also involved in regulation of insulin expression. The invertebrate amphioxus has a gene cluster containing one gene from each of the gene families, whereas in all vertebrates examined to date there are additional copies resultant from ParaHox gene cluster duplications at the base of the vertebrate lineage. Extant vertebrates basal to bony and cartilaginous fish are central to the question of when and how these multiple genes arose in the vertebrate genome. Here, we report the mapping of a ParaHox gene cluster in 2 species of hagfishes. Unexpectedly, these basal vertebrates have lost a functional Xlox gene from this cluster, unlike every other vertebrate examined to date. Furthermore, our phylogenetic analyses suggest that hagfishes may have diverged from the vertebrate lineage before the duplications, which created the multiple ParaHox clusters in jawed vertebrates.
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| 46. |
- Hall-Spencer, Jason, et al.
(författare)
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Impact of ocean acidification on marine organisms - unifying principles and new paradigms
- 2015
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 7:10, s. 5592-5598
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Tidskriftsartikel (refereegranskat)abstract
- This special issue combines original research with seminal reviews of the biological impact of ocean acidification. The ten contributions cover a wide range of topics from chemical and biological responses to increased CO2 and decreased pH to socio-economical sensitivities and adaptation options. Overall, this special issue also highlights the key knowledge gaps and future challenges. These include the need to develop research strategy and experiments that factor in evolution, incorporate natural variability in physical conditions (e.g., pH, temperature, oxygen, food quality and quantity) and ecological interactions. The research presented in this special issue demonstrates the need to study more habitats (e.g., coastal, deep sea) and prioritize species of ecological or economic significance.
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| 47. |
- Havenhand, Jonathan N., 1959, et al.
(författare)
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Försurning i klimatförändringens spår
- 2008
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Ingår i: HAVET 2008. - Stockholm : Naturvårdsverket. ; , s. 27-30
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 48. |
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| 49. |
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| 50. |
- Holm, K., et al.
(författare)
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Functional properties of proteins from the coelomic fluid of the wounded sea star Asterias rubens (L)
- 2010
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Ingår i: Journal of Invertebrate Pathology. - : Academic Press Inc.. - 0022-2011 .- 1096-0805. ; 105, s. 197-199
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Tidskriftsartikel (refereegranskat)abstract
- Impact on viability and adhesion of three protein fractions, separated by size, from the coelomic fluid of wounded Asterias rubens′, was tested on autologous coelomocytes. In addition antimicrobial property of the protein fractions was tested on the Gram-negative bacterium Vibrio parahaemolyticus. All fractions promoted viability and the larger proteins facilitated adhesion of the coelomocytes. The strongest antimicrobial effect was caused by the fraction with the smallest proteins.
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