Heidi Snyman

Publications (5)133.75 Total impact

• Source

  Available from: Michel Vervoort

  Article: Hedgehog signaling regulates segment formation in the annelid Platynereis.

  Nicolas Dray, Kristin Tessmar-Raible, Martine Le Gouar, Laura Vibert, Foteini Christodoulou, Katharina Schipany, Aurélien Guillou, Juliane Zantke, Heidi Snyman, Julien Béhague, Michel Vervoort, Detlev Arendt, Guillaume Balavoine
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  ABSTRACT: Annelids and arthropods share a similar segmented organization of the body whose evolutionary origin remains unclear. The Hedgehog signaling pathway, prominent in arthropod embryonic segment patterning, has not been shown to have a similar function outside arthropods. We show that the ligand Hedgehog, the receptor Patched, and the transcription factor Gli are all expressed in striped patterns before the morphological appearance of segments in the annelid Platynereis dumerilii. Treatments with small molecules antagonistic to Hedgehog signaling disrupt segment formation. Platynereis Hedgehog is not necessary to establish early segment patterns but is required to maintain them. The molecular similarity of segment patterning functions of the Hedgehog pathway in an annelid and in arthropods supports a common origin of segmentation in protostomes.
  Science 07/2010; 329(5989):339-42. · 31.20 Impact Factor
• Article: Ancient animal microRNAs and the evolution of tissue identity.

  Foteini Christodoulou, Florian Raible, Raju Tomer, Oleg Simakov, Kalliopi Trachana, Sebastian Klaus, Heidi Snyman, Gregory J Hannon, Peer Bork, Detlev Arendt
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  ABSTRACT: The spectacular escalation in complexity in early bilaterian evolution correlates with a strong increase in the number of microRNAs. To explore the link between the birth of ancient microRNAs and body plan evolution, we set out to determine the ancient sites of activity of conserved bilaterian microRNA families in a comparative approach. We reason that any specific localization shared between protostomes and deuterostomes (the two major superphyla of bilaterian animals) should probably reflect an ancient specificity of that microRNA in their last common ancestor. Here, we investigate the expression of conserved bilaterian microRNAs in Platynereis dumerilii, a protostome retaining ancestral bilaterian features, in Capitella, another marine annelid, in the sea urchin Strongylocentrotus, a deuterostome, and in sea anemone Nematostella, representing an outgroup to the bilaterians. Our comparative data indicate that the oldest known animal microRNA, miR-100, and the related miR-125 and let-7 were initially active in neurosecretory cells located around the mouth. Other sets of ancient microRNAs were first present in locomotor ciliated cells, specific brain centres, or, more broadly, one of four major organ systems: central nervous system, sensory tissue, musculature and gut. These findings reveal that microRNA evolution and the establishment of tissue identities were closely coupled in bilaterian evolution. Also, they outline a minimum set of cell types and tissues that existed in the protostome-deuterostome ancestor.
  Nature 02/2010; 463(7284):1084-8. · 36.28 Impact Factor
• Source

  Available from: Gáspár Jékely

  Article: Molecular architecture of annelid nerve cord supports common origin of nervous system centralization in bilateria.

  Alexandru S Denes, Gáspár Jékely, Patrick R H Steinmetz, Florian Raible, Heidi Snyman, Benjamin Prud'homme, David E K Ferrier, Guillaume Balavoine, Detlev Arendt
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  ABSTRACT: To elucidate the evolutionary origin of nervous system centralization, we investigated the molecular architecture of the trunk nervous system in the annelid Platynereis dumerilii. Annelids belong to Bilateria, an evolutionary lineage of bilateral animals that also includes vertebrates and insects. Comparing nervous system development in annelids to that of other bilaterians could provide valuable information about the common ancestor of all Bilateria. We find that the Platynereis neuroectoderm is subdivided into longitudinal progenitor domains by partially overlapping expression regions of nk and pax genes. These domains match corresponding domains in the vertebrate neural tube and give rise to conserved neural cell types. As in vertebrates, neural patterning genes are sensitive to Bmp signaling. Our data indicate that this mediolateral architecture was present in the last common bilaterian ancestor and thus support a common origin of nervous system centralization in Bilateria.
  Cell 05/2007; 129(2):277-88. · 32.40 Impact Factor
• Source

  Available from: Patrick R H Steinmetz

  Article: Fluorescent two-color whole mount in situ hybridization in Platynereis dumerilii (Polychaeta, Annelida), an emerging marine molecular model for evolution and development.

  Kristin Tessmar-Raible, Patrick R H Steinmetz, Heidi Snyman, Monika Hassel, Detlev Arendt
  BioTechniques 11/2005; 39(4):460, 462, 464. · 2.67 Impact Factor
• Source

  Available from: Kristin Tessmar-Raible

  Article: Ciliary photoreceptors with a vertebrate-type opsin in an invertebrate brain.

  Detlev Arendt, Kristin Tessmar-Raible, Heidi Snyman, Adriaan W Dorresteijn, Joachim Wittbrodt
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  ABSTRACT: For vision, insect and vertebrate eyes use rhabdomeric and ciliary photoreceptor cells, respectively. These cells show distinct architecture and transduce the light signal by different phototransductory cascades. In the marine rag-worm Platynereis, we find both cell types: rhabdomeric photoreceptor cells in the eyes and ciliary photoreceptor cells in the brain. The latter use a photopigment closely related to vertebrate rod and cone opsins. Comparative analysis indicates that both types of photoreceptors, with distinct opsins, coexisted in Urbilateria, the last common ancestor of insects and vertebrates, and sheds new light on vertebrate eye evolution.
  Science 10/2004; 306(5697):869-71. · 31.20 Impact Factor