Heterogeneity of chromatoid bodies in adult pluripotent stem cells of planarian D ugesia japonica
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Abstract:
The robust regenerative ability of planarians is known to be dependent on adult pluripotent stem cells called neoblasts. One of the morphological features of neoblasts is cytoplasmic ribonucleoprotein granules (chromatoid bodies: CB s), which resemble germ granules present in germline cells in other animals. Previously, we showed by immuno‐electron microscopic analysis that Dj CBC ‐1, a planarian Me31B/Dhh1/ DDX 6 homologue, which is a component of ribonucleoprotein granules, was localized in CB s in the planarian Dugesia japonica . Also, recently it was reported using another planarian species that Y12 antibody recognizing symmetrical dimethylarginine ( sDMA ) specifically binds to CB s in which histone mRNA is co‐localized. Here, we showed by double immunostaining and RNA interference ( RNA i) that Dj CBC ‐1‐containing CB s and Y12‐immunoreactive CB s are distinct structures, suggesting that CB s are composed of heterogeneous populations. We also found that the Y12‐immunoreactive CB s specifically contained a cytoplasmic type of planarian PIWI protein (DjPiwiC). We revealed by RNA i experiments that Y12‐immunoreactive CB s may have anti‐transposable element activity involving the DjPiwiC protein in the neoblasts.Keywords:
Planarian
Aim To monitor the toxic effect of N,N-dimethylformamide on the Dugesia Japonica(Planarian).Methods The effect of DMF on behavior,regeneration,mortality rate,activities of superoxidedismutase(SOD),catalase(CAT),glutathione peroxidase(GSH-PX) and the damage of DNA of planarian were detected.Results The mortality rate of planarian increased obviously with the rising of DMF concentration and exposure time;the planarian regeneration was inhibited by the low dose of DMF;obvious change of SOD activity was caused by DMF ranged from 0 to 0.5%;CAT activity was increased under the treatment of DMF from 0.2% to 0.4%;DNA damage of the planarian was observed after 1% DMF treatment.Conclusion Obvious toxic effects on planarian after treatment by DMF were observed.As planarian is sensitive to DMF,it has the potentiality of DMF contamination detection in water.
Planarian
Dimethyl formamide
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Remodeling is an integral component of tissue homeostasis and regeneration. In planarians, these processes occur constantly in a simple tractable model organism as part of the animal's normal life history. Here, we have studied the gene Gtdap-1, the planarian ortholog of human death-associated protein-1 or DAP-1. DAP-1, together with DAP-kinase, has been identified as a positive mediator of programmed cell death induced by gamma-IFN in HeLa cells. Although the function of DAP-kinase is well characterized, the role of DAP-1 has not been studied in detail. Our findings suggest that Gtdap-1 is involved in autophagy in planarians, and that autophagy plays an essential role in the remodeling of the organism that occurs during regeneration and starvation, providing the necessary energy and building blocks to the neoblasts for cell proliferation and differentiation. The gene functions at the interface between survival and cell death during stress-inducing processes like regeneration and starvation in sexual and asexual races of planarians. Our findings provide insights into the complex interconnections among cell proliferation, homeostasis, and cell death in planarians and perspectives for the understanding of neoblast stem cell dynamics.
Planarian
Flatworm
Model Organism
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Target of Rapamycin (TOR) controls an evolutionarily conserved signaling pathway that modulates cellular growth and division by sensing levels of nutrients, energy and stress. As such, TOR signaling is a crucial component of tissues and organs that translates systemic signals into cellular behavior. The ubiquitous nature of TOR signaling, together with the difficulty of analyzing tissue during cellular turnover and repair, have limited our understanding of how this kinase operates throughout the body. Here, we use the planarian model system to address TOR regulation at the organismal level. The planarian TOR homolog (Smed-TOR) is ubiquitously expressed, including stem cells (neoblasts) and differentiated tissues. Inhibition of TOR with RNA interference severely restricts cell proliferation, allowing the study of neoblasts with restricted proliferative capacity during regeneration and systemic cell turnover. Strikingly, TOR signaling is required for neoblast response to amputation and localized growth (blastema). However, in the absence of TOR signaling, regeneration takes place only within differentiated tissues. In addition, TOR is essential for maintaining the balance between cell division and cell death, and its dysfunction leads to tissue degeneration and lack of organismal growth in the presence of nutrients. Finally, TOR function is likely to be mediated through TOR Complex 1 as its disruption recapitulates signs of the TOR phenotype. Our data reveal novel roles for TOR signaling in controlling adult stem cells at a systemic level and suggest a new paradigm for studying TOR function during physiological turnover and regeneration.
Planarian
TOR signaling
Blastema
Nutrient Sensing
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Planarian
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The high regenerative power of planarian has fascinated scientists for a long time. Although many famous scientists, including Thomas Hunt Morgan, extensively devoted themselves to studying mechanisms underlying regeneration, the planarian regeneration still remains mysterious phenomenon. Recently, mod- ern approaches have been developed and incorporated in planarian research, and several mysterious points were clarified. Here, I focus on old problems of planar- ian stem cells. Planarian stem cells were called neoblasts and considered to be the only cells maintaining proliferative activity and pluripotency. However, recent analyses using molecular markers and FACS sorting revealed their heterogeneity. Now we should change the old view of the planarian stem cell system to one closer to mammalian stem cell systems. These insights indicate the planarian regeneration studies may provide new ideas for handling mouse and human ES cells for thera- peutic use in the near future.
Planarian
Cell Sorting
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Planarians are the most primitive bilateral triploblastic organisms. Most planarian species retain the mechanisms for whole-body regeneration; for example, they can regenerate their cephalic ganglion after complete excision. This powerful whole-body regeneration capacity has made planarians model organisms in regenerative research for more than 240 years. The mysteries of planarian regeneration have been gradually uncovered while newly developed tools and techniques were applied. Exact cell-cell communication has long been understood to be a prerequisite for regeneration. In recent decades, the associated mechanisms have been uncovered at the cellular level. During planarian homeostasis and regeneration, stem cells (neoblasts) are the source of all new cells. The interplay between neoblasts and somatic cells affects the identities and proportions of various tissues during homeostasis and regeneration. Here, we review discoveries that scientists have sought to understand communications between stem cell compartments and other cell types in planarians, and the impact of communications on planarian regeneration. We also highlight challenges and future directions in planarian research, a field that has consistently contributed valuable knowledge of animal regeneration.
Planarian
Flatworm
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Planarian
Turbellaria
Homeostasis
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Planaria
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The high regenerative power of planarian has fascinated scientists for a long time. Although many famous scientists, including Thomas Hunt Morgan, extensively devoted themselves to studying mechanisms underlying regeneration, the planarian regeneration still remains mysterious phenomenon. Recently, modern approaches have been developed and incorporated in planarian research, and several mysterious points were clarified. Here, I focus on old problems of planarian stem cells. Planarian stem cells were called "neoblasts" and considered to be the only cells maintaining proliferative activity and pluripotency. However, recent analyses using molecular markers and FACS sorting revealed their heterogeneity. Now we should change the old view of the planarian stem cell system to one closer to mammalian stem cell systems. These insights indicate the planarian regeneration studies may provide new ideas for handling mouse and human ES cells for therapeutic use in the near future.
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Cell Sorting
Stem cell biology
Regenerative Medicine
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To analyze the feasibility of monitoring the surface water quality using the Dugesia japonica.The asexual reproduction and the regeneration of the planarian in class I-V earth's surface water were observed.There were close relationships between the planarian asexual reproduction and the surface water quality,and the regeneration of the planarian was influenced by different surface water quality.The rates of the planarian asexual reproduction and the regeneration in class I-V earth's surface water were significantly different(p0.05).The planarian could be used to monitor surface water quality.
Planarian
Asexual reproduction
Turbellaria
Flatworm
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Planarian
Turbellaria
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