1,721,082 research outputs found
The past and present of planarians - An interview with Vittorio Gremigni
No full textVittorio Gremigni is a scientific leader in the field of planarian biology with a very long historical perspective. By using electron microscopy, he contributed to the reconstruction of the phylogenesis of free living "Turbellaria", and he pioneered the study of the origin of blastema cells by using chromosomal markers. In this interview, Professor Gremigni describes the steps that moved his career towards the planarian field, the main scientific achievements he obtained and the changes that are taking place in the field. He also discusses recent progress and unanswered questions on planarian neoblasts and regeneratio
Stem cells and neural signalling: the case of neoblast recruitment and plasticity in low dose X-ray treated planarians
Full text linkPlanarians (Platyhelminthes) possess an abundant population of adult stem cells, the neoblasts, capable to give rise to both somatic and germ cells. Although neoblasts share similar morphological features, several pieces of evidence suggest that they constitute a heterogeneous population of cells with distinct ultrastructural and molecular features. We found that in planarians treated with low X-ray doses (5 Gy), only a few neoblasts survive. Among these cells, those located close to the nervous system activate an intense proliferation program and migrate to reconstitute the whole complex neoblast population. This phenomenon is inhibited by the substance P receptor antagonist spantide, and accompanied by the up-regulation of a number of genes implicated in neuronal signalling and plasticity, suggesting that signals of neural origin modulate neoblast proliferation and/or migration. Here, we review these findings and the literature available on the influence of the nervous system on stem cell activity, both in planarians and vertebrates, and we propose 5 Gy-treated planarians as a unique model system to study the influence of neural signalling on stem cell biolog
Planarian Stem Cell Heterogeneity
No full textPlanarian (Platyhelminthes, Triclads) are free-living flatworms endowed with extraordinary regenerative capabilities, i.e., the ability to rebuild any missing body parts also from small fragments. Planarian regenerative capabilities fascinated scientific community since early 1800, including high-standing scientists such as J.T. Morgan and C. M. Child. Today, it is known that planarian regeneration is due to the presence of a wide population of stem cells, the so-called neoblasts. However, the understanding of the nature of cells orchestrating planarian regeneration was a long journey, and several questions still remain unanswered. In this chapter, beginning from the definition of the classical concept of neoblast, we review progressive discoveries that have brought to the modern view of these cells as a highly heterogeneous population of stem cells including pluripotent stem cells and undifferentiated populations of committed progenies
Planarian stem cell niche, the challenge for understanding tissue regeneration
No full textStem cell fate depends on surrounding microenvironment, the so called niche. For this reason, understanding stem cell niche is one of the most challenging target in cell biology field and need to be unraveled with in vivo studies. Planarians offer this unique opportunity, as their stem cells, the neoblasts, are abundant, highly characterized and genetically modifiable by RNA interference in alive animals. However, despite impressive advances have been done in the understanding planarian stem cells and regeneration, only a few information is available in defining signals from differentiated tissues, which affect neoblast stemness and fate. Here, we review on molecular factors that have been found activated in differentiated tissues and directly or indirectly affect neoblast behavior, and we suggest future directions for unravelling this challenge in understanding planarian stem cells
Planarians: a model system for in vivo studying stem cell biology, tissue regeneration, ageing, cancer and host-pathogen interaction
No full text
ANT1 silencing induces glioblastoma cell death
No full textAdenine nucleotide translocases (ANTs) are multitask proteins involved in several aspects of cell metabolism as well as in the regulation of cell death/survival processes [1]. We investigated the role played by ANT isoform 1 in the growth of a human glioblastoma cell line (ADF cells). The silencing of ANT1 isoform by siRNA
strongly reduced ADF cell viability by inducing a non-apoptotic cell death process resembling paraptosis. We
demonstrated that the cell death induced by ANT1 depletion cannot be ascribed to the loss of the ATP/ADP exchange function of this protein. On the contrary, our findings indicate that ANT1-silenced cells experience
oxidative stress mediated by the loss of the ANT1 uncoupling function. Several studies ascribe to ANT1 a pro-apoptotic role due to the observation that ANT1 over-expression sensitizes cells to mitochondrial depolarization or to apoptotic stimuli [2-4]. Here we demonstrate that, despite its pro-apoptotic function at high expression level, the reduction of ANT1 density under a physiological baseline
impairs fundamental functions of this protein in ADF cells leading them to undertake a cell death process.
1. Palmieri F (2004) The mitochondrial transporter family (SLC25): physiological and pathological implications. Pflugers Arch 447, 689-709
2. Bauer MK, Schubert A, Rocks O & Grimm S (1999) Adenine nucleotide translocase-1, a component of the
permeability transition pore, can dominantly induce apoptosis. J Cell Biol 147, 1493-502.
3. Jang JY, Choi Y, Jeon YK, Aung KC & Kim CW (2008) Over-expression of adenine nucleotide translocase 1 (ANT1) induces apoptosis and tumor regression in vivo. BMC Cancer 8, 160.
4. Zamora M, Meroño C, Viñas O & Mampel T (2004) Recruitment of NF-kappaB into mitochondria is involved in adenine nucleotide translocase 1 (ANT1)-induced apoptosis. J Biol Chem 279, 38415-2
A karyological study on populations of Dugesia gonocephala s.l. (Turbellaria: Tricladida)
No full textA karyological analysis was carried out on sexual and fissiparous populations of planarians belonging to the 'Dugesia gonocephala group', collected in localities of the Mediterranean area: Morocco, and Yemen. Euploid (diploid and triploid) chromosome sets are observed in populations reproducing only sexually, whereas hyperdiploid and aneutriploid complements characterize agamous and fissiparous strains. Aneuploidy may occur either associated with an increase in the chromosome number or as a product of rearrangements in numerically balanced chromosome sets. Mitotically unstable B-chromosomes are present in all aneuploid populations. The variety of karyological characteristics encountered is discussed from a cytogenetic and cytotaxonomic standpoint
- …
