9 results on '"Echinodermata"'
Search Results
2. Reconstructing SALMFamide neuropeptide precursor evolution in the phylum Echinodermata: ophiuroid and crinoid sequence data provide new insights.
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Elphick, Maurice R., Semmens, Dean C., Blowes, Liisa M., Levine, Judith, Lowe, Christopher J., Arnone, Maria I., and Clark, Melody S.
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NEUROPEPTIDES ,NERVE tissue proteins ,ECHINODERMATA ,OPHIUROIDEA ,CRINOIDEA - Abstract
The SALMFamides are a family of neuropeptides that act as muscle relaxants in echinoderms. Analysis of genome/transcriptome sequence data from the sea urchin Strongylocentrotus purpuratus (Echinoidea), the sea cucumber Apostichopus japonicus (Holothuroidea), and the starfish Patiria miniata (Asteroidea) reveals that in each species there are two types of SALMFamide precursor: an L-type precursor comprising peptides with a C-terminal LxFamide-type motif and an F-type precursor solely or largely comprising peptides with a C-terminal FxFamide-type motif. Here, we have identified transcripts encoding SALMFamide precursors in the brittle star Ophionotus victoriae (Ophiuroidea) and the feather star Antedon mediterranea (Crinoidea). We have also identified SALMFamide precursors in other species belonging to each of the five echinoderm classes. As in S. purpuratus, A. japonicus, and P. miniata, in O. victoriae there is one L-type precursor and one F-type precursor. However, in A. mediterranea only a single SALMFamide precursor was found, comprising two peptides with a LxFamide-type motif, one with a FxFamide-type motif, five with a FxLamide-type motif, and four with a LxLamide-type motif. As crinoids are basal to the Echinozoa (HolothuroideaCEchinoidea) and Asterozoa (Asteroidea + Ophiuroidea) in echinoderm phylogeny, one model of SALMFamide precursor evolution would be that ancestrally there was a single SALMFamide gene encoding a variety of SALMFamides (as in crinoids), which duplicated in a common ancestor of the Echinozoa and Asterozoa and then specialized to encode L-type SALMFamides or F-type SALMFamides. Alternatively, a second SALMFamide precursor may remain to be discovered or may have been lost in crinoids. Further insights will be obtained if SALMFamide receptors are identified, which would provide a molecular basis for experimental analysis of the functional significance of the "cocktails" of SALMFamides that exist in echinoderms. [ABSTRACT FROM AUTHOR]
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- 2015
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3. Getting around when you're round: quantitative analysis of the locomotion of the blunt-spined brittle star, Ophiocoma echinata.
- Author
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Astley, Henry C.
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ANIMAL locomotion , *QUANTITATIVE research , *OPHIUROIDEA , *ECHINODERMATA , *OCEAN bottom , *TETRAPODS , *SYMMETRY (Biology) , *PSYCHOLOGICAL feedback - Abstract
Brittle stars (Ophiuroidea, Echlnodermata) are pentaradially symmetrical echinoderms that use five multi-jointed limbs to locomote along the seafloor. Prior qualitative descriptions have claimed coordinated movements of the limbs in a manner similar to tetrapod vertebrates, but this has not been evaluated quantitatively. It is uncertain whether the ring-shaped nervous system, which lacks an anatomically defined anterior, is capable of generating rhythmic coordinated movements of multiple limbs. This study tested whether brittle stars possess distinct locomotor modes with strong inter-limb coordination as seen in limbed animals in other phyla (e.g. tetrapods and arthropods), or instead move each limb independently according to local sensory feedback. Limb tips and the body disk were digitized for 56 cycles from 13 individuals moving across sand. Despite their pentaradial anatomy, all Individuals were functionally bilateral, moving along the axis of a central limb via synchronous motions of contralateral limbs (±∼13% phase lag). Two locomotor modes were observed, distinguishable mainly by whether the central limb was directed forwards or backwards. Turning was accomplished without rotation of the body disk by defining a different limb as the center limb and shifting other limb identities correspondingly, and then continuing locomotion in the direction of the newly defined anterior. These observations support the hypothesis that, in spite of their radial body plan, brittle stars employ coordinated, bilaterally symmetrical locomotion. [ABSTRACT FROM AUTHOR]
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- 2012
- Full Text
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4. Biology of a “babysitting” symbiosis in brittle stars: analysis of the interactions between Ophiomastix venosa and Ophiocoma scolopendrina.
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Fourgon, Didier, Jangoux, Michel, and Eeckhaut, Igor
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SYMBIOSIS , *COMMENSALISM , *ECHINODERMATA , *OPHIUROIDEA - Abstract
“Babysitting” symbioses between brittle star species involve juveniles of one species and adults of another. During this phenomenon, reported from many localities in the Indo-Pacific Ocean, juveniles are attached to the disk or lie in the bursa of the adults. The symbiosis between members of Ophiomastix venosa and their host, Ophiocoma scolopendrina, was investigated on the Great Barrier Reef of Toliara (Madagascar) during a 14-month period. The population of O. scolopendrina only occurs on rocky spurs that frequently emerge at low tide, while the population of O. venosa lies in adjacent surge channels that are always immersed. Only juveniles of O. venosa associated with adults of O. scolopendrina may occur on the rocky spurs. Analyses conducted on the populations of the two species showed that (1) the symbiosis is facultative and that symbiotic juveniles migrate into the channels when they reach a disc diameter of 6 mm, and (2) recruitment in the channels occurs in April. Host choice experiments, Y-tube experiments, and experiments assessing the resistance of the ophiuroids to air-drying were conducted in the laboratory. The experiments clearly demonstrated that (1) symbiotic juveniles of O. venosa specifically recognize adults of O. scolopendrina, while free juveniles of the same size do not, and (2) juveniles of O. venosa would not survive air-drying conditions similar to those observed on the spurs at low tides if they were not in symbiosis with adults of O. scolopendrina. [ABSTRACT FROM AUTHOR]
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- 2007
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5. ABUNDANCE AND SIZE DISTRIBUTION DYNAMICS OF ABYSSAL EPIBENTHIC MEGAFAUNA IN THE NORTHEAST PACIFIC.
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Ruhl, Henry A.
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MARINE ecology , *DEEP-sea biology , *ABYSSAL zone , *DEEP-sea animals , *ECHINODERMATA , *ECHINOIDA , *SEA cucumbers , *ANIMAL communities , *OPHIUROIDEA , *BODY size , *BENTHOS - Abstract
The importance of interannual variation in deep-sea abundances is now becoming recognized. There is, however, relatively little known about what processes dominate the observed fluctuations. The abundance and size distribution of the megabenthos have been examined here using a towed camera system at a deep-sea station in the northeast Pacific (Station M) from 1989 to 2004. This 16-year study included 52 roughly seasonal transects averaging 1.2 km in length with over 35600 photographic frames analyzed. Mobile epibenthic megafauna at 4100 m depth have exhibited interannual scale changes in abundance from one to three orders of magnitude. Increases in abundance have now been significantly linked to decreases in mean body size, suggesting that accruals in abundance probably result from the recruitment of young individuals. Examinations of size-frequency histograms indicate several possible recruitment events. Shifts in size-frequency distributions were also used to make basic estimations of individual growth rates from 1 to 6 mm/month, depending on the taxon. Regional intensification in reproduction followed by recruitment within the study area could explain the majority of observed accruals in abundance. Although some adult migration is certainly probable in accounting for local variation in abundances, the slow movements of benthic life stages restrict regional migrations for most taxa. Negative competitive interactions and survivorship may explain the precipitous declines of some taxa. This and other studies have shown that abundances from protozoans to large benthic invertebrates and fishes all have undergone significant fluctuations in abundance at Station M over periods of weeks to years. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
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6. Regional specification in the early embryo of the brittle star Ophiopholis aculeata
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Primus, Alexander E.
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OPHIUROIDEA , *ECHINODERMATA , *PHRYNOPHIURIDA , *OPHIURIDA - Abstract
Abstract: Early embryogenesis has been examined experimentally in several echinoderm and hemichordate classes. Although these studies suggest that the mechanisms which underlie regional specification have been highly conserved within the echinoderm + hemichordate clade, nothing is known about these mechanisms in several other echinoderm classes, including the Ophiuroidea. In this study, early embryogenesis was examined in a very little studied animal, the ophiuroid Ophiopholis aculeata. In O. aculeata, the first two cleavage planes do not coincide with the animal–vegetal axis but rather form approximately 45° off this axis. A fate map of the early embryo was constructed using microinjected lineage tracers. Most significantly, this fate map indicates that there is a major segregation of ectodermal from endomesodermal fates at first cleavage. The distribution of developmental potential in the early embryo was also examined by isolating different regions of the early embryo and following these isolates though larval development. These analyses indicate that endomesodermal developmental potential segregates unequally at first, second, and third cleavage in O. aculeata. These results provide insight into the mechanisms of regional specification in O. aculeata and yield new material for the study of the evolution of echinoderm development. [Copyright &y& Elsevier]
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- 2005
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7. Synergic effects of tryptamine and octopamine on ophiuroid luminescence (Echinodermata).
- Author
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Vanderlinden, C. and Mallefet, J.
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OPHIUROIDEA , *BIOLUMINESCENCE , *NEURAL transmission , *ACETYLCHOLINE , *TRYPTAMINE , *BIOGENIC amines , *ECHINODERMATA - Abstract
In ophiuroids, bioluminescence is under nervous control. Previous studies have shown that acetylcholine is the main neurotransmitter triggering light emission in Amphipholis squamata and Amphiura filiformis. By contrast, none of the neurotransmitters tested so far induced luminescence in two other ophiuroid species, Ophiopsila aranea and Ophiopsila californica. The aim of this work was thus to investigate the putative involvement of two biogenic amines, tryptamine and octopamine, in light emission of three ophiuroid species. A. filiformis responds to both tryptamine and octopamine, mainly on its arm segments, while O. californica only responds to tryptamine stimulation. By contrast, tryptamine and octopamine do not seem to be involved in O. aranea luminescence control since none of these substances induced light emission in this species. The synergic effects of several other drugs with tryptamine and octopamine were also tested. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
8. Discovery of novel representatives of bilaterian neuropeptide families and reconstruction of neuropeptide precursor evolution in ophiuroid echinoderms
- Author
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Andrew F. Hugall, Maurice R. Elphick, Timothy D. O'Hara, Nikara Abylkassimova, Jérôme Delroisse, Luis Alfonso Yañez Guerra, Ismail Moghul, and Meet Zandawala
- Subjects
0301 basic medicine ,Gene Dosage ,Gene Expression ,neuropeptide evolution ,Genome ,Endothelins ,Transcriptome ,neuropeptide-y ,0302 clinical medicine ,Brittle star ,Neuropeptide Y ,lcsh:QH301-705.5 ,Phylogeny ,0303 health sciences ,Deuterostome ,biology ,General Neuroscience ,ophiuroidea ,Anatomy ,eclosion hormone ,Neuropeptide Y receptor ,Biological Evolution ,cchamide ,DNA-Binding Proteins ,Echinoderm ,Insect Hormones ,Echinodermata ,Research Article ,medicine.hormone ,Period (gene) ,Immunology ,Neuropeptide ,Sequence alignment ,Nerve Tissue Proteins ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Phylogenetics ,medicine ,Animals ,Nucleobindins ,Amino Acid Sequence ,Protein Precursors ,030304 developmental biology ,brittle star ,Sequence Homology, Amino Acid ,Research ,Calcium-Binding Proteins ,Neuropeptides ,biology.organism_classification ,030104 developmental biology ,lcsh:Biology (General) ,Evolutionary biology ,Sequence Alignment ,030217 neurology & neurosurgery - Abstract
Neuropeptides are a diverse class of intercellular signalling molecules that mediate neuronal regulation of many physiological and behavioural processes. Recent advances in genome/transcriptome sequencing are enabling identification of neuropeptide precursor proteins in species from a growing variety of animal taxa, providing new insights into the evolution of neuropeptide signalling. Here, detailed analysis of transcriptome sequence data from three brittle star species, Ophionotus victoriae , Amphiura filiformis and Ophiopsila aranea , has enabled the first comprehensive identification of neuropeptide precursors in the class Ophiuroidea of the phylum Echinodermata. Representatives of over 30 bilaterian neuropeptide precursor families were identified, some of which occur as paralogues. Furthermore, homologues of endothelin/CCHamide, eclosion hormone, neuropeptide-F/Y and nucleobinin/nesfatin were discovered here in a deuterostome/echinoderm for the first time. The majority of ophiuroid neuropeptide precursors contain a single copy of a neuropeptide, but several precursors comprise multiple copies of identical or non-identical, but structurally related, neuropeptides. Here, we performed an unprecedented investigation of the evolution of neuropeptide copy number over a period of approximately 270 Myr by analysing sequence data from over 50 ophiuroid species, with reference to a robust phylogeny. Our analysis indicates that the composition of neuropeptide ‘cocktails’ is functionally important, but with plasticity over long evolutionary time scales.
- Published
- 2017
9. High opsin diversity in a non-visual infaunal brittle star
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Sam Dupont, Jérôme Mallefet, Olga Ortega-Martinez, Esther Ullrich-Lüter, Jérôme Delroisse, Maria-Ina Arnone, Patrick Flammang, and UCL - SST/ELI/ELIB - Biodiversity
- Subjects
Opsin ,genetic structures ,Molecular Sequence Data ,Gene Expression ,Brittle star ,Phylogenetics ,biology.animal ,Genetics ,Animals ,Amino Acid Sequence ,Ophiuroidea ,Sea urchin ,Amphiura filiformis ,Phylogeny ,Echinodermata [Echinoderms] ,Genome ,Behavior, Animal ,Opsins ,biology ,Genetic Variation ,Photoreception ,Ophiuroidea [Brittlestars] ,Genomics ,biology.organism_classification ,Strongylocentrotus purpuratus ,eye diseases ,Echinoderm ,Evolutionary biology ,sense organs ,Tube feet ,Transcriptome ,Research Article ,Biotechnology ,Echinodermata - Abstract
Background In metazoans, opsins are photosensitive proteins involved in both vision and non-visual photoreception. Echinoderms have no well-defined eyes but several opsin genes were found in the purple sea urchin (Strongylocentrotus purpuratus) genome. Molecular data are lacking for other echinoderm classes although many species are known to be light sensitive. Results In this study focused on the European brittle star Amphiura filiformis, we first highlighted a blue-green light sensitivity using a behavioural approach. We then identified 13 new putative opsin genes against eight bona fide opsin genes in the genome of S. purpuratus. Six opsins were included in the rhabdomeric opsin group (r-opsins). In addition, one putative ciliary opsin (c-opsin), showing high similarity with the c-opsin of S. purpuratus (Sp-opsin 1), one Go opsin similar to Sp-opsins 3.1 and 3.2, two basal-branch opsins similar to Sp-opsins 2 and 5, and two neuropsins similar to Sp-opsin 8, were identified. Finally, two sequences from one putative RGR opsin similar to Sp-opsin 7 were also detected. Adult arm transcriptome analysis pinpointed opsin mRNAs corresponding to one r-opsin, one neuropsin and the homologue of Sp-opsin 2. Opsin phylogeny was determined by maximum likelihood and Bayesian analyses. Using antibodies designed against c- and r-opsins from S. purpuratus, we detected putative photoreceptor cells mainly in spines and tube feet of A. filiformis, respectively. The r-opsin expression pattern is similar to the one reported in S. purpuratus with cells labelled at the tip and at the base of the tube feet. In addition, r-opsin positive cells were also identified in the radial nerve of the arm. C-opsins positive cells, expressed in pedicellariae, spines, tube feet and epidermis in S. purpuratus were observed at the level of the spine stroma in the brittle star. Conclusion Light perception in A. filiformis seems to be mediated by opsins (c- and r-) in, at least, spines, tube feet and in the radial nerve cord. Other non-visual opsin types could participate to the light perception process indicating a complex expression pattern of opsins in this infaunal brittle star. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1035) contains supplementary material, which is available to authorized users.
- Published
- 2014
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