01834nas a2200217   4500008004100000020001400041245009100055210006900146260000800215300001200223490000700235520121100242100001501453700001601468700002201484700001401506700001701520700001601537700001701553856004601570       2009                        eng d  a0531-556500aThe free-living flatworm Macrostomum lignano: A new model organism for ageing research0 afreeliving flatworm Macrostomum lignano A new model organism for  cApr  a243-2490 v443 aTo study the several elements and causes of ageing, diverse model organisms and methodologies are required. The most frequently used models are Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster and rodents. All have their advantages and disadvantages and allow studying particular aspects of the ageing process. During the last few years, several ageing studies focussed on stem cells and their role in tissue homeostasis. Here we present a new model organism which can study this relation where other model systems fail. The flatworm Macrostomum lignano possesses a dynamic population of likely totipotent somatic stem cells known as neoblasts. Several characteristics qualify M. lignano as a suitable model system for ageing studies in general and more specifically for gaining more insight in the causal relation between stem cells, ageing and rejuvenation. In this review, we will briefly describe the species and its life history, and discuss the role of its stem cells in ageing and rejuvenation. We also give an overview of the available experimental tools that allow a multidisciplinary approach for studying ageing in M. lignano. (C) 2008 Elsevier Inc. All rights reserved.1 aMouton, S.1 aWillems, M.1 aBraeckman, B., P.1 aEgger, B.1 aLadurner, P.1 aScharer, L.1 aBorgonie, G.  uhttps://nematodes.myspecies.info/node/11502245nas a2200181   4500008004100000020001400041245008800055210006900143260000800212490000600220520170800226100001501934700001601949700001301965700002201978700001702000856004602017       2009                        eng d  a1742-999400aDemographic analysis reveals gradual senescence in the flatworm Macrostomum lignano0 aDemographic analysis reveals gradual senescence in the flatworm   cJul0 v63 aFree-living flatworms ("Turbellaria") are appropriate model organisms to gain better insight into the role of stem cells in ageing and rejuvenation. Ageing research in flatworms is, however, still scarce. This is partly due to culture difficulties and the lack of a complete set of demographic data, including parameters such as median lifespan and age-specific mortality rate. In this paper, we report on the first flatworm survival analysis. We used the species Macrostomum lignano, which is an emerging model for studying the reciprocal influence between stem cells, ageing and rejuvenation. This species has a median lifespan of 205 +/- 13 days (average +/- standard deviation [SD]) and a 90(th) percentile lifespan of 373 +/- 32 days. The maximum lifespan, however, is more than 745 days, and the average survival curve is characterised by a long tail because a small number of individuals lives twice as long as 90% of the population. Similar to earlier observations in a wide range of animals, in M. lignano the age-specific mortality rate increases exponentially, but levels off at the oldest ages. To compare the senescence of M. lignano with that of other ageing models, we determined the mortality rate doubling time, which is 0.20 +/- 0.02 years. As a result, we can conclude that M. lignano shows gradual senescence at a rate similar to the vertebrate ageing models Rattus norvegicus and Mus musculus. We argue that M. lignano is a suitable model for ageing and rejuvenation research, and especially for the role of stem cells in these processes, due to its accessible stem cell system and regeneration capacity, and the possibility of combining stem cell studies with demographic analyses.1 aMouton, S.1 aWillems, M.1 aBack, P.1 aBraeckman, B., P.1 aBorgonie, G.  uhttps://nematodes.myspecies.info/node/11601510nas a2200217   4500008004100000020001400041245011400055210006900169260000800238300001200246490000800258520087300266100001601139700001501155700001501170700001401185700001501199700001501214700001701229856004601246       2009                        eng d  a0362-252500aOntogeny of the Complex Sperm in the Macrostomid Flatworm Macrostomum lignano (Macrostomorpha, Rhabditophora)0 aOntogeny of the Complex Sperm in the Macrostomid Flatworm Macros  cFeb  a162-1740 v2703 aSpermiogenesis in Macrostomum lignano (Macrostomorpha, Rhabditophora) is described using light- and electron microscopy of the successive stages in sperm development. Ovoid spermatids develop to highly complex, elongated sperm possessing an undulating distal (anterior) process (or "feeler"), bristles, and a proximal (posterior) brush. In particular, we present a detailed account of the morphology and ontogeny of the bristles, describing for the first time the formation of a highly specialized bristle complex consisting of several parts. This complex is ultimately reduced when sperm are mature. The implications of the development of this bristle complex on both sperm maturation and the evolution and function of the bristles are discussed. The assumed homology between bristles and flagellae questioned. J. Morphol. 270:162-174, 2009. (C) 2008 Wiley-Liss, Inc.1 aWillems, M.1 aLeroux, F.1 aClaeys, M.1 aBoone, M.1 aMouton, S.1 aArtois, T.1 aBorgonie, G.  uhttps://nematodes.myspecies.info/node/10701562nas a2200241   4500008004100000020001400041245014700055210006900202260000800271300001200279490000800291520083200299100001601131700001401147700001401161700001501175700001801190700001701208700001701225700001501242700001701257856004601274       2009                        eng d  a0949-944X00aEmbryonic origins of hull cells in the flatworm Macrostomum lignano through cell lineage analysis: developmental and phylogenetic implications0 aEmbryonic origins of hull cells in the flatworm Macrostomum lign  cAug  a409-4170 v2193 aThe development of macrostomid flatworms is of interest for evolutionary developmental biology research because these taxa combine characteristics of the canonical spiral cleavage pattern with significant deviations from this pattern. One such deviation is the formation of hull cells, which surround the remaining embryonic primordium during early development. Using live observations with a 4D microscope system, histology, and 3D reconstructions, we analyzed the ontogeny of these hull cells in the macrostomid model organism Macrostomum lignano. Our cell lineage analysis allowed us to find the precursors of the hull cells in this species. We discuss the relation between macrostomid development and the development of other spiralians and the question of whether hull cells are homologous within rhabditophoran flatworms.1 aWillems, M.1 aEgger, B.1 aWolff, C.1 aMouton, S.1 aHouthoofd, W.1 aFonderie, P.1 aCouvreur, M.1 aArtois, T.1 aBorgonie, G.  uhttps://nematodes.myspecies.info/node/108