| 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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