title: Distribution of the stem cells (neoblasts) in the planarian Dugesia japonica.
abstract: It has been postulated that the high regeneration ability of planarians is supported by totipotent stem cells, called neoblasts. There have been a few reports showing the distribution of neoblasts in planarians. However, the findings were not completely consistent. To determine the distribution of neoblasts, we focused on proliferating cell nuclear antigen (PCNA), which is present in proliferative cells. We cloned and sequenced the cDNA of PCNA from the planarian Dugesia japonica and produced an antiserum recognizing the gene product. X-ray irradiation caused rapid loss of all PCNA-positive cells and loss of the neoblasts (which were morphologically defined by the presence of the chromatoid body), strongly suggesting that all PCNA-positive cells were true neoblasts. Using the antiserum, we were successful in identifying the neoblasts more clearly than any previous work. In addition to their dispersed distribution in the dorsal and ventral mesenchyme, the neoblasts were distributed as clusters along the midline and bilateral lines in the dorsal mesenchyme. We also examined the behavior of the neoblasts after decapitation. Decapitation did not seem to affect the migration of neoblasts far from the wound. We demonstrated here that DjPCNA is a powerful tool for identifying planarian neoblasts.
authors.affiliation: Laboratory of Regeneration Biology, Department of Life Science, University of Hyogo (Formerly: Himeji Institute of Technology), Harima Science Garden City, Koto 3-2-1, Kamigori, Akou-gun, Hyogo, 678-1297, Japan. orii@sci.u-hyogo.ac.jp
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Orii
authors.forename: Takashige
authors.initials: T
authors.lastname: Sakurai
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010932:Planarians / Q000166:cytology* / Q000235:genetics / Q000528:radiation effects; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000166:cytology*
chemical_list: D015415:Biomarkers; D018076:DNA, Complementary; D018809:Proliferating Cell Nuclear Antigen