title: Cell cycle features of C. elegans germline stem/progenitor cells vary temporally and spatially.
abstract: Many organisms accumulate a pool of germline stem cells during development that is maintained in later life. The dynamics of establishment, expansion and homeostatic maintenance of this pool are subject to both developmental and physiological influences including the availability of a suitable niche microenvironment, nutritional status, and age. Here, we investigated the dynamics of germline proliferation during stages of expansion and homeostasis, using the C. elegans germ line as a model. The vast majority of germ cells in the proliferative zone are in interphase stages of mitosis (G1, S, G2) rather than in the active mitotic (M) phase. We examined mitotic index and DNA content, comparing different life stages, mutants, and physiological conditions. We found that germ cells in larval stages cycle faster than in adult stages, but that this difference could not be attributed to sexual fate of the germ cells. We also found that larval germ cells exhibit a lower average DNA content compared to adult germ cells. We extended our analysis to consider the effects of distance from the niche and further found that the spatial pattern of DNA content differs between larval and adult stages in the wild type and among mutants in pathways that interfere with cell cycle progression, cell fate, or both. Finally, we characterized expansion of the proliferative pool of germ cells during adulthood, using a regeneration paradigm (ARD recovery) in which animals are starved and re-fed. We compared adult stage regeneration and larval stage expansion, and found that the adult germ line is capable of rapid accumulation but does not sustain a larval-level mitotic index nor does it recapitulate the larval pattern of DNA content. The regenerated germ line does not reach the number of proliferative zone nuclei seen in the continuously fed adult. Taken together, our results suggest that cell cycle dynamics are under multiple influences including distance from the niche, age and/or maturation of the germ line, nutrition and, possibly, latitude for physical expansion.
authors.affiliation: Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
authors.forename: Debasmita
authors.initials: D
authors.lastname: Roy
authors.affiliation: Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
authors.forename: David
authors.initials: D
authors.lastname: Michaelson
authors.affiliation: Departments of Population Health and Environmental Medicine, Division of Biostatistics, New York University School of Medicine, 540 First Avenue, New York, NY, 10016, USA.
authors.forename: Tsivia
authors.initials: T
authors.lastname: Hochman
authors.affiliation: Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY, 10065, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Santella
authors.affiliation: Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY, 10065, USA.
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Bao
authors.affiliation: Departments of Population Health and Environmental Medicine, Division of Biostatistics, New York University School of Medicine, 540 First Avenue, New York, NY, 10016, USA.
authors.forename: Judith D
authors.initials: JD
authors.lastname: Goldberg
authors.affiliation: Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA. Electronic address: jane.hubbard@med.nyu.edu.
authors.forename: E Jane Albert
authors.initials: EJA
authors.lastname: Hubbard
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000378:metabolism; D002453:Cell Cycle; D019070:Cell Lineage; D049109:Cell Proliferation; D004247:DNA / Q000378:metabolism; D005854:Germ Cells / Q000166:cytology*; D007814:Larva / Q000166:cytology; D008940:Mitotic Index; D009154:Mutation / Q000235:genetics; D012038:Regeneration; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013997:Time Factors
chemical_list: D004247:DNA
keywords: Adult reproductive diapause; Cell fate; Insulin; Irises; Notch; S6 Kinase