title: Isolation of the choanocyte in the fresh water sponge, Ephydatia fluviatilis and its lineage marker, Ef annexin.
abstract: In order to investigate the cellular system of the freshwater sponge, Ephydatia fluviatilis, we isolated a molecular marker for the most prominent cell type, the choanocyte. After feeding sponge with fluorescent beads, fluorescent-labeled choanocytes were collected by fluorescence activated cell sorting (FACS). By protein profiling choanocyte and archeocyte (stem cell)-rich fractions, proteins characteristic of choanocyte were identified. The partial amino-acid sequence of one of the proteins characteristic of choanocyte matches the deduced amino-acid sequence of sponge expression tag (EST) clones and mouse annexin VII. These EST clones overlap and encode a protein, designated Ef annexin, which includes four annexin domains. Whole mount in situ hybridization shows Ef annexin expression in chamber-forming choanocytes in 7-day-old sponge, leading us to conclude that Ef annexin can be used as a choanocyte marker. In the early development stage, Ef annexin expression can be detected in both large single cells, characteristic of archeocytes, and cells forming 2-, 4- and multiple-cell clusters. These results indicate that Ef annexin is initially expressed in the choanocyte-committed archeocyte which then undergoes several mitotic cell divisions to form a choanocyte chamber. This suggests that the single choanocyte chamber essentially originates from a single archeocyte.
authors.affiliation: Group for Evolutionary Regeneration Biology, Center for Developmental Biology, RIKEN Kobe, 2-2-3 Minatojima-Minami, Chuo-ku, Kobe, Hyogo 650-0047, Japan. funayama@cdb.riken.jp
authors.forename: Noriko
authors.initials: N
authors.lastname: Funayama
authors.forename: Mikiko
authors.initials: M
authors.lastname: Nakatsukasa
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Hayashi
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017310:Annexin A7 / Q000378:metabolism; D017302:Annexins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D020224:Expressed Sequence Tags; D005434:Flow Cytometry; D051379:Mice; D008969:Molecular Sequence Data; D011161:Porifera / Q000166:cytology* / Q000378:metabolism; D040901:Proteomics; D013234:Stem Cells / Q000737:chemistry / Q000378:metabolism*
chemical_list: D017310:Annexin A7; D017302:Annexins; D015415:Biomarkers