2024-03-29T08:00:16Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/303482022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116Transient occurrence of vasa-expressing cells in nongenital segments during embryonic development in the oligochaete annelid Tubifex tubifexOyama, AtsukoShimizu, TakashiPrimordial germ cellsOligochaete annelidTubifex tubifexEmbryogenesisvasaBody segments464The primordial germ cells (PGCs) in the oligochaete annelid Tubifex tubifex are mesodermal in origin and are located in the two midbody segments X and XI in which the testis and the ovary are formed, respectively. To identify a molecular marker for the Tubifex PGCs, we isolated the Tubifex homologue (Ttu-vas) of the Drosophila vasa gene. Using whole-mount in situ hybridization, we examined the spatial expression patterns of Ttu-vas from 1-cell stage through juvenile stage. Ttu-vas mRNA is present as a maternal transcript distributed broadly throughout the early stages. Ttu-vas is expressed in all of the early cleavage blastomeres, in which Ttu-vas RNA associates with mitotic spindles and pole plasms. Expression of Ttu-vas gradually becomes restricted, first to teloblasts, then to their blast cell progeny comprising the germ bands (GBs), and finally to a set of large ventral cells (termed VE cells) in a variable set of midbody segments including the genital segments (X and XI). At the end of embryogenesis, VE cells are confined to genital segments where they are presumably germline precursors in the juvenile. Staining with a cross-reacting anti-Vasa antibody suggested that VE cells express Ttu-vas protein to the same extent irrespective of their positions along the anteroposterior axis. A set of cell ablation experiments suggested that VE cells are derived from the mesodermal teloblast lineage and that the emergence of VE cells takes place independently of the presence of the ectodermal GBs that normally overlay the mesoderm. These results suggest that T. tubifex generates supernumerary presumptive PGCs during embryogenesis whose number is variable among embryos.SpringerJournal Articleapplication/pdfhttp://hdl.handle.net/2115/30348https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/30348/1/AOandTS2007Rev.pdf0949-944X1432-041XDevelopment Genes and Evolution217106756902007-10enginfo:pmid/17851685info:doi/10.1007/s00427-007-0180-1The original publication is available at www.springerlink.comauthor