@article {124,
	title = {To Be or Not to Be a Flatworm: The Acoel Controversy},
	journal = {PLoS ONEPLoS ONE},
	volume = {4},
	number = {5},
	year = {2009},
	note = {Egger, Bernhard Steinke, Dirk Tarui, Hiroshi De Mulder, Katrien Arendt, Detlev Borgonie, Gaetan Funayama, Noriko Gschwentner, Robert Hartenstein, Volker Hobmayer, Bert Hooge, Matthew Hrouda, Martina Ishida, Sachiko Kobayashi, Chiyoko Kuales, Georg Nishimura, Osamu Pfister, Daniela Rieger, Reinhard Salvenmoser, Willi Smith, Julian, III Technau, Ulrich Tyler, Seth Agata, Kiyokazu Salzburger, Walter Ladurner, Peter},
	month = {May},
	abstract = {Since first described, acoels were considered members of the flatworms (Platyhelminthes). However, no clear synapomorphies among the three large flatworm taxa - the Catenulida, the Acoelomorpha and the Rhabditophora have been characterized to date. Molecular phylogenies, on the other hand, commonly positioned acoels separate from other flatworms. Accordingly, our own multi-locus phylogenetic analysis using 43 genes and 23 animal species places the acoel flatworm Isodiametra pulchra at the base of all Bilateria, distant from other flatworms. By contrast, novel data on the distribution and proliferation of stem cells and the specific mode of epidermal replacement constitute a strong synapomorphy for the Acoela plus the major group of flatworms, the Rhabditophora. The expression of a piwi-like gene not only in gonadal, but also in adult somatic stem cells is another unique feature among bilaterians. These two independent stem-cell-related characters put the Acoela into the Platyhelminthes-Lophotrochozoa clade and account for the most parsimonious evolutionary explanation of epidermal cell renewal in the Bilateria. Most available multigene analyses produce conflicting results regarding the position of the acoels in the tree of life. Given these phylogenomic conflicts and the contradiction of developmental and morphological data with phylogenomic results, the monophyly of the phylum Platyhelminthes and the position of the Acoela remain unresolved. By these data, both the inclusion of Acoela within Platyhelminthes, and their separation from flatworms as basal bilaterians are well-supported alternatives.},
	isbn = {1932-6203},
	author = {Egger, B. and Steinke, D. and Tarui, H. and De Mulder, K. and Arendt, D. and Borgonie, G. and Funayama, N. and Gschwentner, R. and Hartenstein, V. and Hobmayer, B. and Hooge, M. and Hrouda, M. and Ishida, S. and Kobayashi, C. and Kuales, G. and Nishimura, O. and Pfister, D. and Rieger, R. and Salvenmoser, W. and Smith, J. and Technau, U. and Tyler, S. and Agata, K. and Salzburger, W. and Ladurner, P.}
}
@article {125,
	title = {Stem cells are differentially regulated during development, regeneration and homeostasis in flatworms},
	journal = {Developmental BiologyDevelopmental Biology},
	volume = {334},
	number = {1},
	year = {2009},
	note = {De Mulder, Katrien Pfister, Daniela Kuales, Georg Egger, Bernhard Salvenmoser, Willi Willems, Maxime Steger, Jessica Fauster, Katja Micura, Ronald Borgonie, Gaetan Ladurner, Peter},
	month = {Oct},
	pages = {198-212},
	abstract = {The flatworm stem cell system is exceptional within the animal kingdom, as totipotent stem cells (neoblasts) are the only dividing cells within the organism. In contrast to most organisms, piwi-like gene expression in. flatworms is extended from germ cells to somatic stem cells. We describe the isolation and characterization of the piwi homologue macpiwi in the flatworm Macrostomum lignano. We use in situ hybridization, antibody staining and RNA interference to study macpiwi expression and function in adults, during postembryonic development, regeneration and upon starvation. We found novelties regarding piwi function and observed differences to current piwi functions in flatworms. First, macpiwi was essential for the maintenance of somatic stem cells in adult animals. A knock-down of macpiwi led to a complete elimination of stem cells and death of the animals. Second, the regulation of stem cells was different in adults and regenerates compared to postembryonic development. Third, sexual reproduction of M. lignano allowed to follow germline formation during postembryonic development, regeneration, and starvation. Fourth, piwi expression in hatchlings further supports an embryonic formation of the germline in M. lignano. Our findings address new questions in flatworm stem cell research and provide a basis for comparison with higher organisms. (C) 2009 Elsevier Inc. All rights reserved.},
	isbn = {0012-1606},
	author = {De Mulder, K. and Pfister, D. and Kuales, G. and Egger, B. and Salvenmoser, W. and Willems, M. and Steger, J. and Fauster, K. and Micura, R. and Borgonie, G. and Ladurner, P.}
}
@article {126,
	title = {Characterization of the stem cell system of the acoel <i>Isodiametra pulchra</i>},
	journal = {Bmc Developmental BiologyBmc Developmental Biology},
	volume = {9},
	year = {2009},
	note = {De Mulder, Katrien Kuales, Georg Pfister, Daniela Willems, Maxime Egger, Bernhard Salvenmoser, Willi Thaler, Marlene Gorny, Anne-Kathrin Hrouda, Martina Borgonie, Gaetan Ladurner, Peter},
	month = {Dec},
	abstract = {Background: Tissue plasticity and a substantial regeneration capacity based on stem cells are the hallmark of several invertebrate groups such as sponges, cnidarians and Platyhelminthes. Traditionally, Acoela were seen as an early branching clade within the Platyhelminthes, but became recently positioned at the base of the Bilateria. However, little is known on how the stem cell system in this new phylum is organized. In this study, we wanted to examine if Acoela possess a neoblast-like stem cell system that is responsible for development, growth, homeostasis and regeneration. Results: We established enduring laboratory cultures of the acoel Isodiametra pulchra (Acoela, Acoelomorpha) and implemented in situ hybridization and RNA interference (RNAi) for this species. We used BrdU labelling, morphology, ultrastructure and molecular tools to illuminate the morphology, distribution and plasticity of acoel stem cells under different developmental conditions. We demonstrate that neoblasts are the only proliferating cells which are solely mesodermally located within the organism. By means of in situ hybridisation and protein localisation we could demonstrate that the piwi-like gene ipiwi1 is expressed in testes, ovaries as well as in a subpopulation of somatic stem cells. In addition, we show that germ cell progenitors are present in freshly hatched worms, suggesting an embryonic formation of the germline. We identified a potent stem cell system that is responsible for development, homeostasis, regeneration and regrowth upon starvation. Conclusions: We introduce the acoel Isodiametra pulchra as potential new model organism, suitable to address developmental questions in this understudied phylum. We show that neoblasts in I. pulchra are crucial for tissue homeostasis, development and regeneration. Notably, epidermal cells were found to be renewed exclusively from parenchymally located stem cells, a situation known only from rhabditophoran flatworms so far. For further comparison, it will be important to analyse the stem cell systems of other key-positioned understudied taxa.},
	isbn = {1471-213X},
	author = {De Mulder, K. and Kuales, G. and Pfister, D. and Willems, M. and Egger, B. and Salvenmoser, W. and Thaler, M. and Gorny, A. K. and Hrouda, M. and Borgonie, G. and Ladurner, P.}
}
@article {100,
	title = {Potential of <i>Macrostomum lignano</i> to recover from gamma-ray irradiation},
	journal = {Cell and Tissue ResearchCell and Tissue Research},
	volume = {339},
	number = {3},
	year = {2010},
	note = {De Mulder, Katrien Kuales, Georg Pfister, Daniela Egger, Bernhard Seppi, Thomas Eichberger, Paul Borgonie, Gaetan Ladurner, Peter},
	month = {Mar},
	pages = {527-542},
	abstract = {Stem cells are the only proliferating cells in flatworms and can be eliminated by irradiation with no damage to differentiated cells. We investigated the effect of fractionated irradiation schemes on Macrostomum lignano, namely, on survival, gene expression, morphology and regeneration. Proliferating cells were almost undetectable during the first week post-treatment. Cell proliferation and gene expression were restored within 1 month in a dose-dependent manner following exposure to up to 150 Gy irradiation. During recovery, stem cells did not cross the midline but were restricted within lateral compartments. An accumulated dose of 210 Gy resulted in a lethal phenotype. Our findings demonstrate that M. lignano represents a suitable model system for elucidating the effect of irradiation on the stem cell system in flatworms and for improving our understanding of the recovery potential of severely damaged stem-cell systems.},
	isbn = {0302-766X},
	author = {De Mulder, K. and Kuales, G. and Pfister, D. and Egger, B. and Seppi, T. and Eichberger, P. and Borgonie, G. and Ladurner, P.}
}
