Project description:Female germ cells develop into oocytes, with the capacity for totipotency. In most animals, these remarkable cells are specified during development and cannot be regenerated. By contrast, planarians, known for their regenerative prowess, can regenerate germ cells. To uncover mechanisms required for female germ cell development and regeneration, we generated gonad-specific transcriptomes and identified genes whose expression defines progressive stages of female germ cell development. Strikingly, early female germ cells share molecular signatures with the pluripotent stem cells driving planarian regeneration. We uncovered spatial heterogeneity within somatic ovarian cells and found that a regionally enriched FoxL homolog is required for oocyte differentiation, but not specification, suggestive of functionally distinct somatic compartments. Unexpectedly, a neurotransmitter-biosynthetic enzyme, AADC, is also expressed in somatic gonadal cells, and plays opposing roles in female and male germ cell development. Thus, somatic gonadal cells deploy conserved factors to regulate germ cell development and regeneration in planarians.
Project description:Adult stem cells are tissue-specific cells with the capacity to self-renew and differentiate to continually replace cells lost to normal physiological turnover or injury. Neoblasts, the planarian stem cells, are widely distributed throughout the body mesenchyme, driving constitutive renewal of tissues during homeostasis and endowing planarians with the remarkable capacity to regenerate wholly from tiny tissue fragments. Neoblasts are the only dividing cells in planarians and are believed to be collectively comprised of both a heterogeneous population of pluripotent cells with broad differentiation potential and also lineage-committed progenitor cells that give rise to specific tissues. Recent technology has allowed one to isolate stem cells so we used a well-established method to isolate planarian stem cells by Hoechst blue staining and flow cytometry. To understand the molecular mechanisms underlying neoblast differentiation, we performed an RNA-Seq analysis of X1 and Xins cells looking at the differentially expressed genes between the two populations. Examine gene expression profiles of adult flatwormâ??s X1 and Xins cell types. The experiment was performed in quadruplicate yielding a total of 8 samples.
Project description:The transcriptome of a cell dictates its unique cell-type biology. We used single-cell RNA sequencing to determine the transcriptomes for essentially every cell type of a complete animal: the regenerative planarian Schmidtea mediterranea. Planarians contain a diverse array of cell types, possess lineage progenitors for differentiated cells (including pluripotent stem cells), and constitutively express positional information, making them ideal for this undertaking. We generated data for 66,783 cells, defining transcriptomes for known and many previously unknown planarian cell types and for putative transition states between stem and differentiated cells. We also uncovered regionally expressed genes in muscle, which harbors positional information. Identifying the transcriptomes for potentially all cell types for many organisms should be readily attainable and is a powerful new approach to metazoan biology.
Project description:Adult stem cells are tissue-specific cells with the capacity to self-renew and differentiate to continually replace cells lost to normal physiological turnover or injury. Neoblasts, the planarian stem cells, are widely distributed throughout the body mesenchyme, driving constitutive renewal of tissues during homeostasis and endowing planarians with the remarkable capacity to regenerate wholly from tiny tissue fragments. Neoblasts are the only dividing cells in planarians and are believed to be collectively comprised of both a heterogeneous population of pluripotent cells with broad differentiation potential and also lineage-committed progenitor cells that give rise to specific tissues. Recent technology has allowed one to isolate stem cells so we used a well-established method to isolate planarian stem cells by Hoechst blue staining and flow cytometry. To understand the molecular mechanisms underlying neoblast differentiation, we performed an RNA-Seq analysis of X1 and Xins cells looking at the differentially expressed genes between the two populations.
Project description:The freshwater planarian Schmidtea mediterranea is well known by its amazing regeneration capabilities thanks to the presence of adult stem cells, the neoblasts, the only proliferative cells and responsible for the differentiation in all the cell types of the organism. This study involves the creation of separated transcript libraries from both, isolated neoblasts and differentiated cells, as well as their posterior sequencing and quantification through Digital Gene Expression (DGE) for the characterization of the neoblast transcriptome. Three DGE libraries were produced from FACS isolated cell populations X1 (proliferating stem cells, S/G2/M), X2 (a mix of proliferating stem cells and stem cell progeny, G0/G1) and Xin (differentiated cells, G0/G1). Cells were isolated from a pool of 32 regenerating animals two days after being cut off pre- and post-pharingeally to trigger regeneration and neoblast proliferation.
Project description:Planarian neoblasts are pluripotent, adult somatic stem cells and lineage-primed progenitors required for the production and maintenance of all differentiated cell types, including the germline. Neoblasts, originally defined by Harriet Randolph as undifferentiated, embryonic-like cells residing in the adult parenchyma, are frequently compared to embryonic stem cells yet their developmental origin remains obscure. We investigated the provenance of neoblasts during S. mediterranea embryogenesis, and report that neoblasts arise from an anarchic, cycling piwi-1+ population that is wholly responsible for production of all temporary and definitive organs during embryogenesis. Early embryonic piwi-1+ cells are molecularly and functionally distinct from neoblasts: they express unique cohorts of early embryo enriched transcripts and the cells behave differently than neoblasts in cell transplantation assays. Neoblast lineages, established as organogenesis commences, persist into adulthood, where they act as agents of tissue homeostasis and regeneration.
Project description:The freshwater planarian Schmidtea mediterranea is well known by its amazing regeneration capabilities thanks to the presence of adult stem cells, the neoblasts, the only proliferative cells and responsible for the differentiation in all the cell types of the organism. This study involves the creation of separated transcript libraries from both, isolated neoblasts and differentiated cells, as well as their posterior sequencing and quantification through Digital Gene Expression (DGE) for the characterization of the neoblast transcriptome.