Effect of the brittle star Amphiura filiformis
 (Amphiuridae, Echinodermata) on oxygen flux into the sediment

ABSTRACTAmongst the echinoderms the class Ophiuroidea is of particular interest for its phylogenetic position, ecological importance, developmental and regenerative biology. However, compared to other echinoderms, notably echinoids (sea urchins), relatively little is known about developmental changes in gene expression in ophiuroids. To address this issue we have generated and assembled a large RNAseq data set of four key stages of development in the brittle star Amphiura filiformis and a de novo reference transcriptome of comparable quality to that of a model echinoderm - the sea urchin Strongyloncentrotus purpuratus. Furthermore, we provide access to the new data via a web interface: http://www.echinonet.eu/shiny/Amphiura_filiformis/. With a focus on skeleton development, we have identified highly conserved genes associated with the development of a biomineralized skeleton. We also identify important class-specific characters, including the independent duplication of the msp130 class of genes in different echinoderm classes and the unique occurrence of spicule matrix (sm) genes in echinoids. Using a new quantification pipeline for our de novo transcriptome, validated with other methodologies, we find major differences between brittle stars and sea urchins in the temporal expression of many transcription factor genes. This divergence in developmental regulatory states is more evident in early stages of development when cell specification begins, than when cells initiate differentiation. Our findings indicate that there has been a high degree of gene regulatory network rewiring in the evolution of echinoderm larval development.Data DepositionsAll sequence reads are available at Genbank SRR4436669 - SRR4436674. Any sequence alignments used are available by the corresponding author upon request.

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A puzzling homology: a brittle star using a putative cnidarian-type luciferase for bioluminescence

Open Biology ◽

10.1098/rsob.160300 ◽

2017 ◽

Vol 7 (4) ◽

pp. 160300 ◽

Cited By ~ 14

Author(s):

Jérôme Delroisse ◽

Esther Ullrich-Lüter ◽

Stefanie Blaue ◽

Olga Ortega-Martinez ◽

Igor Eeckhaut ◽

...

Keyword(s):

Light Emission ◽

Brittle Star ◽

Luciferase Expression ◽

Amphiura Filiformis ◽

Selective Forces ◽

Luciferase Enzyme ◽

Phylogenomic Analyses ◽

Functional Shift ◽

First Time

Bioluminescence relies on the oxidation of a luciferin substrate catalysed by a luciferase enzyme. Luciferins and luciferases are generic terms used to describe a large variety of substrates and enzymes. Whereas luciferins can be shared by phylogenetically distant organisms which feed on organisms producing them, luciferases have been thought to be lineage-specific enzymes. Numerous light emission systems would then have co-emerged independently along the tree of life resulting in a plethora of non-homologous luciferases. Here, we identify for the first time a candidate luciferase of a luminous echinoderm, the ophiuroid Amphiura filiformis . Phylogenomic analyses identified the brittle star predicted luciferase as homologous to the luciferase of the sea pansy Renilla (Cnidaria), contradicting with the traditional viewpoint according to which luciferases would generally be of convergent origins. The similarity between the Renilla and Amphiura luciferases allowed us to detect the latter using anti- Renilla luciferase antibodies. Luciferase expression was specifically localized in the spines which were demonstrated to be the bioluminescent organs in vivo . However, enzymes homologous to the Renilla luciferase but unable to trigger light emission were also identified in non-luminous echinoderms and metazoans. Our findings strongly indicate that those enzymes, belonging to the haloalkane dehalogenase family, might then have been convergently co-opted into luciferases in cnidarians and echinoderms. In these two benthic suspension-feeding species, similar ecological pressures would constitute strong selective forces for the functional shift of these enzymes and the emergence of bioluminescence.

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Fine structure of the luminous spines and luciferase detection in the brittle star Amphiura filiformis

Zoologischer Anzeiger ◽

10.1016/j.jcz.2017.05.001 ◽

2017 ◽

Vol 269 ◽

pp. 1-12 ◽

Cited By ~ 4

Author(s):

Jérôme Delroisse ◽

Esther Ullrich-Lüter ◽

Stefanie Blaue ◽

Igor Eeckhaut ◽

Patrick Flammang ◽

...

Keyword(s):

Fine Structure ◽

Brittle Star ◽

Amphiura Filiformis

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De novo transcriptome of the European brittle star Amphiura filiformis pluteus larvae

Marine Genomics ◽

10.1016/j.margen.2015.05.014 ◽

2015 ◽

Vol 23 ◽

pp. 109-121 ◽

Cited By ~ 15

Author(s):

Jérôme Delroisse ◽

Olga Ortega-Martinez ◽

Sam Dupont ◽

Jérôme Mallefet ◽

Patrick Flammang

Keyword(s):

De Novo ◽

Brittle Star ◽

De Novo Transcriptome ◽

Amphiura Filiformis

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FGF signalling plays similar roles in development and regeneration of the skeleton in the brittle star Amphiura filiformis

10.1101/632968 ◽

2019 ◽

Author(s):

Anna Czarkwiani ◽

David V. Dylus ◽

Luisana Carballo ◽

Paola Oliveri

Keyword(s):

Large Scale ◽

Developmental Process ◽

Skeletal Development ◽

Signalling Pathway ◽

Brittle Star ◽

Differential Analysis ◽

Regulatory Module ◽

Amphiura Filiformis ◽

Fgf Signalling ◽

First Time

AbstractRegeneration is an adult developmental process considered to be an epiphenomenon of embryonic development. Although several studies have shown that various embryonic genes are expressed during regeneration, there have been no large-scale, direct and functional comparative studies between the development and regeneration of a specific structure in one animal. Here, we use the brittle star Amphiura filiformis to characterise the role of the FGF signalling pathway during skeletal development and regeneration. In both processes, we find the ligands expressed in ectodermal cells flanking underlying mesodermal cells, and the receptors expressed specifically by these skeletogenic cells. Perturbation of FGF but not VEGF signalling during skeletogenesis completely inhibited skeleton formation in both embryogenesis and regeneration, without affecting other key developmental processes like cell migration or proliferation. Transcriptome-wide differential analysis identified a highly similar cohort of skeletogenic differentiation genes downstream of the FGF signalling pathway, whereas upstream transcription factors involved in the initial specification of the skeletogenic lineage where unaffected. Comparison to the sea urchin indicated that many of the affected genes are associated with differentiation. Moreover, several genes showed no homology to a cohort from other species, leading to the discovery of brittle star specific, downstream skeletogenic genes. In conclusion, our results show that the FGF pathway is crucial for skeletogenesis in the brittle star, as it is in other deuterostomes, and for the first time provide evidence for the re-deployment of a gene regulatory module during both regeneration and development.

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