title: Adult somatic progenitor cells and hematopoiesis in oysters.
abstract: Long-lived animals show a non-observable age-related decline in immune defense, which is provided by blood cells that derive from self-renewing stem cells. The oldest living animals are bivalves. Yet, the origin of hemocytes, the cells involved in innate immunity, is unknown in bivalves and current knowledge about mollusk adult somatic stem cells is scarce. Here we identify a population of adult somatic precursor cells and show their differentiation into hemocytes. Oyster gill contains an as yet unreported irregularly folded structure (IFS) with stem-like cells bathing into the hemolymph. BrdU labeling revealed that the stem-like cells in the gill epithelium and in the nearby hemolymph replicate DNA. Proliferation of this cell population was further evidenced by phosphorylated-histone H3 mitotic staining. Finally, these small cells, most abundant in the IFS epithelium, were found to be positive for the stemness marker Sox2. We provide evidence for hematopoiesis by showing that co-expression of Sox2 and Cu/Zn superoxide dismutase, a hemocyte-specific enzyme, does not occur in the gill epithelial cells but rather in the underlying tissues and vessels. We further confirm the hematopoietic features of these cells by the detection of Filamin, a protein specific for a sub-population of hemocytes, in large BrdU-labeled cells bathing into gill vessels. Altogether, our data show that progenitor cells differentiate into hemocytes in the gill, which suggests that hematopoiesis occurs in oyster gills.
authors.affiliation: Universités Montpellier 2 et 1, Montpellier, 34095 France CRBM CNRS UMR 5237, Montpellier, 34293 France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Jemaà
authors.affiliation: Universités Montpellier 2 et 1, Montpellier, 34095 France CRBM CNRS UMR 5237, Montpellier, 34293 France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Morin
authors.affiliation: Universités Montpellier 2 et 1, Montpellier, 34095 France IGMM CNRS UMR 5535, Montpellier, 34293 France.
authors.forename: Patricia
authors.initials: P
authors.lastname: Cavelier
authors.affiliation: Universités Montpellier 2 et 1, Montpellier, 34095 France IGH CNRS UPR 1142, Montpellier, 34396, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Cau
authors.affiliation: Université de Strasbourg, Strasbourg, 67081 France IPHC CNRS UMR7178, Strasbourg, 67037 France.
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Strub
authors.affiliation: Universités Montpellier 2 et 1, Montpellier, 34095 France CRBM CNRS UMR 5237, Montpellier, 34293 France IFREMER, LGP, La Tremblade, 17390 France claude.delsert@crbm.cnrs.fr.
authors.forename: Claude
authors.initials: C
authors.lastname: Delsert
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D004247:DNA / Q000096:biosynthesis; D005880:Gills / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism*; D006410:Hematopoiesis; D006434:Hemocytes / Q000166:cytology / Q000502:physiology*; D010125:Ostreidae / Q000166:cytology / Q000502:physiology*; D055748:SOXB1 Transcription Factors / Q000378:metabolism; D013234:Stem Cells / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D055748:SOXB1 Transcription Factors; D004247:DNA; D013482:Superoxide Dismutase
keywords: Adult somatic progenitor cells; Hematopoiesis; Hemocytes; Marine invertebrates; Mollusk