共查询到20条相似文献,搜索用时 15 毫秒
1.
Pfister D De Mulder K Hartenstein V Kuales G Borgonie G Marx F Morris J Ladurner P 《Developmental biology》2008,319(1):146-159
We have isolated and identified the vasa homologue macvasa, expressed in testes, ovaries, eggs and somatic stem cells of the flatworm Macrostomum lignano. Molecular tools such as in situ hybridization and RNA interference were developed for M. lignano to study gene expression and function. Macvasa expression was followed during postembryonic development, regeneration and in starvation experiments. We were able to follow gonad formation in juveniles and the reformation of gonads from stem cells after amputation by in situ hybridization and a specific Macvasa antibody. Expression of macvasa in the germ cells was highly affected by feeding conditions and correlated with the decrease and regrowth of the gonads. RNA interference showed specific down-regulation of macvasa mRNA and protein. The absence of Macvasa did not influence gonad formation and stem cell proliferation. Our results corroborate the exclusive nature of the flatworm stem cell system but challenge the concept of a solely postembryonic specification of the germ line in Platyhelminthes. We address the transition of somatic stem cells to germ cells and speculate on Macrostomum as a system to unravel the mechanisms of preformation or epigenesis in the evolution of germ line specification from somatic stem cells. 相似文献
2.
Xin Zhou Giorgia Battistoni Osama El Demerdash James Gurtowski Julia Wunderer Ilaria Falciatori Peter Ladurner Michael C. Schatz Gregory J. Hannon Kaja A. Wasik 《RNA (New York, N.Y.)》2015,21(11):1885-1897
PIWI proteins and piRNA pathways are essential for transposon silencing and some aspects of gene regulation during animal germline development. In contrast to most animal species, some flatworms also express PIWIs and piRNAs in somatic stem cells, where they are required for tissue renewal and regeneration. Here, we have identified and characterized piRNAs and PIWI proteins in the emerging model flatworm Macrostomum lignano. We found that M. lignano encodes at least three PIWI proteins. One of these, Macpiwi1, acts as a key component of the canonical piRNA pathway in the germline and in somatic stem cells. Knockdown of Macpiwi1 dramatically reduces piRNA levels, derepresses transposons, and severely impacts stem cell maintenance. Knockdown of the piRNA biogenesis factor Macvasa caused an even greater reduction in piRNA levels with a corresponding increase in transposons. Yet, in Macvasa knockdown animals, we detected no major impact on stem cell self-renewal. These results may suggest stem cell maintenance functions of PIWI proteins in flatworms that are distinguishable from their impact on transposons and that might function independently of what are considered canonical piRNA populations. 相似文献
3.
Daniela Pfister Katrien De Mulder Isabelle Philipp Georg Kuales Martina Hrouda Paul Eichberger Gaetan Borgonie Volker Hartenstein Peter Ladurner 《Frontiers in zoology》2007,4(1):1-14
Background
Flatworms are characterized by an outstanding stem cell system. These stem cells (neoblasts) can give rise to all cell types including germ cells and power the exceptional regenerative capacity of many flatworm species. Macrostomum lignano is an emerging model system to study stem cell biology of flatworms. It is complementary to the well-studied planarians because of its small size, transparency, simple culture maintenance, the basal taxonomic position and its less derived embryogenesis that is more closely related to spiralians. The development of cell-, tissue- and organ specific markers is necessary to further characterize the differentiation potential of flatworm stem cells. Large scale in situ hybridization is a suitable tool to identify possible markers. Distinguished genes identified in a large scale screen in combination with manipulation of neoblasts by hydroxyurea or irradiation will advance our understanding of differentiation and regulation of the flatworm stem cell system.Results
We have set up a protocol for high throughput large scale whole mount in situ hybridization for the flatworm Macrostomum lignano. In the pilot screen, a number of cell-, tissue- or organ specific expression patterns were identified. We have selected two stem cell- and germ cell related genes – macvasa and macpiwi – and studied effects of hydroxyurea (HU) treatment or irradiation on gene expression. In addition, we have followed cell proliferation using a mitosis marker and bromodeoxyuridine labeling of S-phase cells after various periods of HU exposure or different irradiation levels. HU mediated depletion of cell proliferation and HU induced reduction of gene expression was used to generate a cDNA library by suppressive subtractive hybridization. 147 differentially expressed genes were sequenced and assigned to different categories.Conclusion
We show that Macrostomum lignano is a suitable organism to perform high throughput large scale whole mount in situ hybridization. Genes identified in such screens – together with BrdU/H3 labeling – can be used to obtain information on flatworm neoblasts. 相似文献4.
Animals show a large variability of lifespan, ranging from short‐lived as Caenorhabditis elegans to immortal as Hydra. A fascinating case is flatworms, in which reversal of aging by regeneration is proposed, yet conclusive evidence for this rejuvenation‐by‐regeneration hypothesis is lacking. We tested this hypothesis by inducing regeneration in the sexual free‐living flatworm Macrostomum lignano. We studied survival, fertility, morphology, and gene expression as a function of age. Here, we report that after regeneration, genes expressed in the germline are upregulated at all ages, but no signs of rejuvenation are observed. Instead, the animal appears to be substantially longer lived than previously appreciated, and genes expressed in stem cells are upregulated with age, while germline genes are downregulated. Remarkably, several genes with known beneficial effects on lifespan when overexpressed in mice and C. elegans are naturally upregulated with age in M. lignano, suggesting that molecular mechanism for offsetting negative consequences of aging has evolved in this animal. We therefore propose that M. lignano represents a novel powerful model for molecular studies of aging attenuation, and the identified aging gene expression patterns provide a valuable resource for further exploration of anti‐aging strategies. 相似文献
5.
Kirill Ustyantsev Jakub Wudarski Igor Sukhikh Filipa Reinoite Stijn Mouton Eugene Berezikov 《Genetics》2021,218(3)
Regeneration-capable flatworms are informative research models to study the mechanisms of stem cell regulation, regeneration, and tissue patterning. The free-living flatworm Macrostomum lignano is currently the only flatworm where stable transgenesis is available, and as such it offers a powerful experimental platform to address questions that were previously difficult to answer. The published transgenesis approach relies on random integration of DNA constructs into the genome. Despite its efficiency, there is room and need for further improvement and diversification of transgenesis methods in M. lignano. Transposon-mediated transgenesis is an alternative approach, enabling easy mapping of the integration sites and the possibility of insertional mutagenesis studies. Here, we report for the first time that transposon-mediated transgenesis using piggyBac can be performed in M. lignano to create stable transgenic lines with single-copy transgene insertions. 相似文献
6.
Traditionally, regeneration research has been closely tied to flatworm research, as flatworms (Plathelminthes) were among
the first animals where the phenomenon of regeneration was discovered. Since then, the main focus of flatworm regeneration
research was on triclads, for which various phenomena were observed and a number of theories developed. However, free-living
flatworms encompass a number of other taxa where regeneration was found to be possible. This review aims to display and to
compare regeneration in all major free-living flatworm taxa, with special focus on a new player in the field of regeneration,
Macrostomum lignano (Macrostomorpha). Findings on the regeneration capacity of this organism provide clues for links between regeneration and
(post-)embryonic development, starvation, and asexual reproduction. The role of the nervous system and especially the brain
for regeneration is discussed, and similarities as well as particularities in regeneration among free-living flatworms are
pointed out. 相似文献
7.
Egger B Ladurner P Nimeth K Gschwentner R Rieger R 《Development genes and evolution》2006,216(10):565-577
The lion’s share of studies on regeneration in Plathelminthes (flatworms) has been so far carried out on a derived taxon of rhabditophorans, the freshwater planarians (Tricladida), and has shown this group’s outstanding regeneration capabilities in detail. Sharing a likely totipotent stem cell system, many other flatworm taxa are capable of regeneration as well. In this paper, we present the regeneration capacity of Macrostomum lignano, a representative of the Macrostomorpha, the basal-most taxon of rhabditophoran flatworms and one of the most basal extant bilaterian protostomes. Amputated or incised transversally, obliquely, and longitudinally at various cutting levels, M. lignano is able to regenerate the anterior-most body part (the rostrum) and any part posterior of the pharynx, but cannot regenerate a head. Repeated regeneration was observed for 29 successive amputations over a period of almost 12 months. Besides adults, also first-day hatchlings and older juveniles were shown to regenerate after transversal cutting. The minimum number of cells required for regeneration in adults (with a total of 25,000 cells) is 4,000, including 160 neoblasts. In hatchlings only 1,500 cells, including 50 neoblasts, are needed for regeneration. The life span of untreated M. lignano was determined to be about 10 months.An erratum to this article can be found at 相似文献
8.
Bernhard Egger Dirk Steinke Hiroshi Tarui Katrien De Mulder Detlev Arendt Ga?tan Borgonie Noriko Funayama Robert Gschwentner Volker Hartenstein Bert Hobmayer Matthew Hooge Martina Hrouda Sachiko Ishida Chiyoko Kobayashi Georg Kuales Osamu Nishimura Daniela Pfister Reinhard Rieger Willi Salvenmoser Julian Smith III Ulrich Technau Seth Tyler Kiyokazu Agata Walter Salzburger Peter Ladurner 《PloS one》2009,4(5)
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. 相似文献
9.
Seung-Hwan Kim Antonia H. Holway Suzanne Wolff Andrew Dillin W. Matthew Michael 《The Journal of cell biology》2009,184(4):613-627
Yb regulates the proliferation of both germline and somatic stem cells in the Drosophila melanogaster ovary by activating piwi and hh expression in niche cells. In this study, we show that Yb protein is localized as discrete cytoplasmic spots exclusively in the somatic cells of the ovary and testis. These spots, which are different from all known cytoplasmic structures in D. melanogaster, are evenly electron-dense spheres 1.5 µm in diameter (herein termed the Yb body). The Yb body is frequently associated with mitochondria and a less electron-dense sphere of similar size that appears to be RNA rich. There are one to two Yb bodies/cell, often located close to germline cells. The N-terminal region of Yb is required for hh expression in niche cells, whereas the C-terminal region is required for localization to Yb bodies. The entire Yb protein is necessary for piwi expression in niche cells. A double mutant of Yb and a novel locus show male germline loss, revealing a function for Yb in male germline stem cell maintenance. 相似文献
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11.
Katrien De Mulder Georg Kuales Daniela Pfister Bernhard Egger Thomas Seppi Paul Eichberger Gaetan Borgonie Peter Ladurner 《Cell and tissue research》2010,339(3):527-542
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. 相似文献
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13.
Melanie Issigonis Akshada B. Redkar Tania Rozario Umair W. Khan Rosa Mejia-Sanchez Sylvain W. Lapan Peter W. Reddien Phillip A. Newmark 《PLoS biology》2022,20(7)
Sexually reproducing animals segregate their germline from their soma. In addition to gamete-producing gonads, planarian and parasitic flatworm reproduction relies on yolk cell–generating accessory reproductive organs (vitellaria) supporting development of yolkless oocytes. Despite the importance of vitellaria for flatworm reproduction (and parasite transmission), little is known about this unique evolutionary innovation. Here, we examine reproductive system development in the planarian Schmidtea mediterranea, in which pluripotent stem cells generate both somatic and germ cell lineages. We show that a homolog of the pluripotency factor Klf4 is expressed in primordial germ cells (PGCs), presumptive germline stem cells (GSCs), and yolk cell progenitors. Knockdown of this klf4-like (klf4l) gene results in animals that fail to specify or maintain germ cells; surprisingly, they also fail to maintain yolk cells. We find that yolk cells display germ cell–like attributes and that vitellaria are structurally analogous to gonads. In addition to identifying a new proliferative cell population in planarians (yolk cell progenitors) and defining its niche, our work provides evidence supporting the hypothesis that flatworm germ cells and yolk cells share a common evolutionary origin. 相似文献
14.
Bernhard Egger Robert Gschwentner Michael W Hess Katharina T Nimeth Zbigniew Adamski Maxime Willems Reinhard Rieger Willi Salvenmoser 《BMC developmental biology》2009,9(1):41-15
Background
Macrostomum lignano is a small free-living flatworm capable of regenerating all body parts posterior of the pharynx and anterior to the brain. We quantified the cellular composition of the caudal-most body region, the tail plate, and investigated regeneration of the tail plate in vivo and in semithin sections labeled with bromodeoxyuridine, a marker for stem cells (neoblasts) in S-phase. 相似文献15.
Makoto Kashima Kiyokazu Agata Norito Shibata 《Development, growth & differentiation》2020,62(6):407-422
Planarians have a remarkable regenerative ability owing to their adult pluripotent stem cells (aPSCs), which are called “neoblasts.” Planarians maintain a considerable number of neoblasts throughout their adulthood to supply differentiated cells for the maintenance of tissue homeostasis and asexual reproduction (fission followed by regeneration). Thus, planarians serve as a good model to study the regulatory mechanisms of in vivo aPSCs. In asexually reproducing invertebrates, such as sponge, Hydra, and planaria, piwi family genes are the markers most commonly expressed in aPSCs. While piwi family genes are known as guardians against transposable elements in the germline cells of animals that only sexually propagate, their functions in the aPSC system have remained elusive. In this review, we introduce recent knowledge on the PIWI family proteins in the aPSC system in planarians and other organisms and discuss how PIWI family proteins contribute to the regulation of the aPSC system. 相似文献
16.
17.
Freija Verdoodt Maxime Willems Ineke Dhondt Wouter Houthoofd Wim Bert Winnok H. De Vos 《Cell biology international》2012,36(12):1251-1259
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 neoblasts was ~13 h. During early regeneration, no significant change in Ts was observed. 相似文献
18.
In many animals, germline development is initiated by proteins and RNAs that are expressed maternally. PIWI proteins and their associated small noncoding PIWI-interacting RNAs (piRNAs), which guide PIWI to target RNAs by base-pairing, are among the maternal components deposited into the germline of the Drosophila early embryo. Piwi has been extensively studied in the adult ovary and testis, where it is required for transposon suppression, germline stem cell self-renewal, and fertility. Consequently, loss of Piwi in the adult ovary using piwi-null alleles or knockdown from early oogenesis results in complete sterility, limiting investigation into possible embryonic functions of maternal Piwi. In this study, we show that the maternal Piwi protein persists in the embryonic germline through gonad coalescence, suggesting that maternal Piwi can regulate germline development beyond early embryogenesis. Using a maternal knockdown strategy, we find that maternal Piwi is required for the fertility and normal gonad morphology of female, but not male, progeny. Following maternal piwi knockdown, transposons were mildly derepressed in the early embryo but were fully repressed in the ovaries of adult progeny. Furthermore, the maternal piRNA pool was diminished, reducing the capacity of the PIWI/piRNA complex to target zygotic genes during embryogenesis. Examination of embryonic germ cell proliferation and ovarian gene expression showed that the germline of female progeny was partially masculinized by maternal piwi knockdown. Our study reveals a novel role for maternal Piwi in the germline development of female progeny and suggests that the PIWI/piRNA pathway is involved in germline sex determination in Drosophila. 相似文献
19.
20.
Nimeth KT Egger B Rieger R Salvenmoser W Peter R Gschwentner R 《Cell and tissue research》2007,327(3):637-646
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.
This work was supported by FWF Grant (P16618; P.I. Rieger, Innsbruck). 相似文献