title: Identification and origin of the germline stem cells as revealed by the expression of nanos-related gene in planarians.
abstract: The planarian's remarkable regenerative ability is thought to be supported by the stem cells (neoblasts) found throughout its body. Here we report the identification of a subpopulation of neoblasts, which was revealed by the expression of the nanos-related gene of the planarian Dugesia japonica, termed Djnos. Djnos-expressing cells in the asexual planarian were distributed to the prospective ovary or testes forming region in the sexual planarian. During sexualization, Djnos-expressing cells produce germ cells, suggesting that in the asexual state these cells were kept as germline stem cells for the oogonia and spermatogonia. Interestingly, the germline stem cells were indistinguishable from the neoblasts by morphology and X-ray sensitivity and did not seem to contribute to the regeneration at all. Germline stem cells initially appear in the growing infant planarian, suggesting that germline stem cells are separated from somatic stem cells in the planarian. Thus, planarian neoblasts can be classified into two groups; somatic stem cells for regeneration and tissue renewal, and germline stem cells for production of germ cells during sexualization. However, Djnos-positive cells appeared in the newly formed trunk region from the head piece, suggesting that somatic stem cells can convert to germline stem cells.
authors.affiliation: Laboratory of Regeneration Biology, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akou-gun, Hyogo 678-1297, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Sato
authors.forename: Norito
authors.initials: N
authors.lastname: Shibata
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Orii
authors.forename: Reiko
authors.initials: R
authors.lastname: Amikura
authors.forename: Takashige
authors.initials: T
authors.lastname: Sakurai
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
authors.forename: Satoru
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D005854:Germ Cells / Q000378:metabolism; D015801:Helminth Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010932:Planarians / Q000235:genetics*; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D015801:Helminth Proteins; C117549:vas-related protein, Dugesia japonica