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Wnt/Frizzled/ss-catenin-based signaling systems play diverse roles in metazoan development, being involved not only in the establishment of body axes in embryogenesis but also in regulating stem cell fate in mammalian post-embryonic development. We have studied the role the canonical Wnt cascade plays in stem cell fate determination in Hydractinia, a member(More)
We have studied the role the canonical Wnt pathway plays in hydroid pattern formation during embryonic development and metamorphosis. Transcripts of Wnt and Tcf were asymmetrically deposited in the oocyte and subsequent developmental stages, marking the sites of first cleavage, posterior larval pole and the upcoming head of the metamorphosed polyp. To(More)
  • G Plickert
  • 1989
The low-molecular weight proportion altering factor (PAF) from colonial hydroids has general animalizing effects on morphogenesis in hydroid development. On the cellular level, the factor stimulates the formation of nerve cells in several developmental stages of Hydractinia echinata. Treatment during metamorphosis yielded a fivefold increase in the number(More)
The evolutionary origin of stem cell pluripotency is an unresolved question. In mammals, pluripotency is limited to early embryos and is induced and maintained by a small number of key transcription factors, of which the POU domain protein Oct4 is considered central. Clonal invertebrates, by contrast, possess pluripotent stem cells throughout their life,(More)
Two morphogenetic factors have been isolated from tissue of colonial hydroids. Both exert strong effects on pattern formation during metamorphosis, regeneration and colony development. Polyp-inhibiting factor (PIF) is a bivalent inhibitor which strongly affects head and bud formation but acts weakly on stolon branching. Proportion-altering factor (PAF) is a(More)
S-phase cells in intact animals of the coelenterate species Eirene viridula, Hydractinia echinata, Hydra attenuata, and Hydra magnipapillata incorporate the thymidine analogue bromodeoxyuridine (BrdU) into newly synthesized DNA. BrdU-labelled nuclei divide and cells appear to undergo normal differentiation. Whole-mount preparations and macerated tissues(More)
We studied the role of Wnt signaling in axis formation during metamorphosis and regeneration in the cnidarian Hydractinia. Activation of Wnt downstream events during metamorphosis resulted in a complete oralization of the animals and repression of aboral structures (i.e. stolons). The expression of Wnt3, Tcf and Brachyury was upregulated and became(More)
Peptides are increasingly attracting attention as primary signals in the control of development. Even though a large number of peptides have been characterized in cnidarians, little experimental evidence addresses their endogenous role. The life cycle of Hydractinia echinata includes metamorphosis from planula larva into the adult stage of the polyp. This(More)
With the rapid increase of the quantity of molecular data, many animals joined the ranks of the so-called 'emerging models' of Evo-Devo. One of the necessary steps in converting an emerging model into an established one is gaining comprehensive knowledge of its normal embryonic development. The marine colonial hydrozoan Hydractinia echinata - an excellent(More)
Metamorphosin A (MMA) isolated from the anthozoan Anthopleura elegantissima has recently been shown to interfere with developmental control in the colonial hydroid Hydractinia echinata. In order to identify the functional homologue in this species we have cloned cDNAs of the precursor protein from Hydractinia and, for comparison, precursor sequences from(More)