Regeneration in Macrostomum lignano (Platyhelminthes): Cellular dynamics in the neoblast stem cell system

Institute of Zoology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria.
Cell and Tissue Research (Impact Factor: 3.57). 04/2007; 327(3):637-46. DOI: 10.1007/s00441-006-0299-9
Source: PubMed


Neoblasts are potentially totipotent stem cells and the only proliferating cells in adult Platyhelminthes. We have examined the cellular dynamics of neoblasts during the posterior regeneration of Macrostomum lignano. Double-labeling of neoblasts with bromodeoxyuridine and the anti-phospho histone H3 mitosis marker has revealed a complex cellular response in the first 48 h after amputation; this response is different from that known to occur during regeneration in triclad platyhelminths and in starvation/feeding experiments in M. lignano. Mitotic activity is reduced during the first 8 h of regeneration but, at 48 h after amputation, reaches almost twice the value of control animals. The total number of S-phase cells significantly increases after 1 day of regeneration. A subpopulation of fast-cycling neoblasts surprisingly shows the same dynamics during regeneration as those in control animals. Wound healing and regeneration are accompanied by the formation of a distinct blastema. These results present new insights, at the cellular level, into the early regeneration of rhabditophoran Platyhelminthes.

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    • "During anterior regeneration, pax-6 has been shown to be expressed in the developing central nervous system and ocelli (Loosli et al., 1996), otx is expressed in the developing central nervous system but not ocelli (Charpignon, 2007), and vision-related six and opsin genes are expressed in the brain and ocelli (Charpignon, 2007). "
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    ABSTRACT: Animals differ markedly in their ability to regenerate, yet still little is known about how regeneration evolves. In recent years, important advances have been made in our understanding of animal phylogeny and these provide new insights into the phylogenetic distribution of regeneration. The developmental basis of regeneration is also being investigated in an increasing number of groups, allowing commonalities and differences across groups to become evident. Here, we focus on regeneration in the Spiralia, a group that includes several champions of animal regeneration, as well as many groups with more limited abilities. We review the phylogenetic distribution and developmental processes of regeneration in four major spiralian groups: annelids, nemerteans, platyhelminths, and molluscs. Although comparative data are still limited, this review highlights phylogenetic and developmental patterns that are emerging regarding regeneration in spiralians and identifies important avenues for future research.
    The International Journal of Developmental Biology 12/2014; 58:623 - 634. DOI:10.1387/ijdb.140142ab · 1.90 Impact Factor
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    • "M. lignano is a well-suited model system to study the distribution, differentiation, and migration of stem cells [56-61] as well as the expression and function of stem cell and germ line genes in adult animals, during postembryonic development and during regeneration [50,52]. M. lignano has a high regeneration capacity [62,63] and detailed studies on the regeneration of the region anterior to the eyes [61], head regeneration [49], and tail-plate regeneration [64] have been performed. In the present study we take advantage of the fact that M. lignano is able to completely regenerate an amputated tail-plate within less than 10 days [62,64]. "
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    ABSTRACT: Free-living flatworms, in both marine and freshwater environments, are able to adhere to and release from a substrate several times within a second. This reversible adhesion relies on adhesive organs comprised of three cell types: an adhesive gland cell, a releasing gland cell, and an anchor cell, which is a modified epidermal cell responsible for structural support. However, nothing is currently known about the molecules that are involved in this adhesion process. In this study we present the detailed morphology of the adhesive organs of the free-living marine flatworm Macrostomum lignano. About 130 adhesive organs are located in a horse-shoe-shaped arc along the ventral side of the tail plate. Each organ consists of exactly three cells, an adhesive gland cell, a releasing gland cell, and an anchor cell. The necks of the two gland cells penetrate the anchor cell through a common pore. Modified microvilli of the anchor cell form a collar surrounding the necks of the adhesive- and releasing glands, jointly forming the papilla, the outer visible part of the adhesive organs. Next, we identified an intermediate filament (IF) gene, macif1, which is expressed in the anchor cells. RNA interference mediated knock-down resulted in the first experimentally induced non-adhesion phenotype in any marine animal. Specifically, the absence of intermediate filaments in the anchor cells led to papillae with open tips, a reduction of the cytoskeleton network, a decline in hemidesmosomal connections, and to shortened microvilli containing less actin. Our findings reveal an elaborate biological adhesion system in a free-living flatworm, which permits impressively rapid temporary adhesion-release performance in the marine environment. We demonstrate that the structural integrity of the supportive cell, the anchor cell, is essential for this adhesion process: the knock-down of the anchor cell-specific intermediate filament gene resulted in the inability of the animals to adhere. The RNAi mediated changes of the anchor cell morphology are comparable to situations observed in human gut epithelia. Therefore, our current findings and future investigations using this powerful flatworm model system might contribute to a better understanding of the function of intermediate filaments and their associated human diseases.
    Frontiers in Zoology 02/2014; 11(1):12. DOI:10.1186/1742-9994-11-12 · 3.05 Impact Factor
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    • "In M. lignano, the presence of a population of fast-cycling neoblasts has been described, additional to the main population of cycling neoblasts (Nimeth et al., 2007). These fast-cycling cells cycle through the whole S, and G2-phase in just 2 h. "
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    ABSTRACT: Platyhelminthes are highly attractive models for addressing fundamental aspects of stem cell biology in vivo. These organisms possess a unique stem cell system comprised of neoblasts that are the only proliferating cells during adulthood. We have investigated Ts (S-phase duration) of neoblasts during homoeostasis and regeneration in the flatworm, Macrostomum lignano. A double immunohistochemical technique was used, performing sequential pulses with the thymidine analogues CldU (chlorodeoxyuridine) and IdU (iododeoxyuridine), separated by variable chase times in the presence of colchicine. Owing to the localized nature of the fluorescent signals (cell nuclei) and variable levels of autofluorescence, standard intensity-based colocalization analyses could not be applied to accurately determine the colocalization. Therefore, an object-based colocalization approach was devised to score the relative number of double-positive cells. Using this approach, Ts (S-phase duration) in the main population of neoblast
    International Journal of Cell Biology 12/2011; 36:1251-1259. DOI:10.1042/CBI20120187
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