
We investigated the regulatory mechanism of primitive hematopoiesis in zebrafish (Danio rerio) embryos with particular reference to the role of a death receptor (zDR) gene, based on a morpholino (MO) knockdown approach.MOs targeting the zDR and chordin (Chd) were injected into naturally spawned embryos at one- to four-cell stage. A random sequence (RS) MO was used as a control. Effects on hemoglobin formation (Hb), apoptosis, and lineage-specific gene expression were examined. Embryos injected with zDR, Chd, and RS-MOs were denoted zDR(mo), zChd(mo), and zRS(mo), respectively. Those co-injected with Chd+zDR-MOs and Chd+RS-MOs were abbreviated zChd+DR(mo) and zChd+RS(mo).zDR mRNA expression was restricted to the intermediate cell mass of wild-type (WT) and zChd(mo) embryos. At 48 hours postfertilization, zDR(mo) embryos showed increased Hb compared with WT or zRS(mo) embryos (2.36 x 10(-2) +/- 1.13 x 10(-3) vs 1.85 x 10(-2) +/- 5.60 x 10(-4) vs 1.79 x 10(-2) +/- 1.31 x 10(-3) U, p < 0.05). zChd+DR(mo) embryos also showed increased Hb compared with zChd(mo) or zChd+RS(mo) embryos (4.60 x 10(-2) +/- 2.79 x 10(-3) vs 3.17 x 10(-2) +/- 1.07 x 10(-3) vs 3.05 x 10(-2) +/- 1.25 x 10(-3) U, p < 0.05). zDR-MO reduced apoptosis, as shown by reduced terminal transferase-mediated dUTP nick end-labeling staining in zChd+DR(mo) compared with zChd+RS(mo) embryos and caspase-3 activity in zDR(mo) vs zRS(mo) (0.525 +/- 0.094 vs 0.953 +/- 0.113 U, p < 0.05), and zChd+DR(mo) vs zChd+RS(mo) embryos (0.247 +/- 0.121 vs 1.180 +/- 0.082, p < 0.05). zChd+DR(mo) embryos showed upregulation of erythroid-specific embryonic hemoglobin gene expression but not that of a myeloid-specific myeloperoxidase gene.Knockdown of zDR in zebrafish embryos decreased apoptosis and increased Hb, suggesting that zDR may regulate primitive hematopoiesis during development.
Caspases - drug effects - metabolism, Embryo, Nonmammalian, Receptors, Tumor Necrosis Factor - administration & dosage - genetics - metabolism, Apoptosis, Research & Experimental Medicine, Receptors, Tumor Necrosis Factor, Hemoglobins, Receptors, Zebrafish - embryology - genetics - metabolism, BMP-4, Tumor Necrosis Factor - administration & dosage - genetics - metabolism, Morpholines - administration & dosage, 1102 Cardiorespiratory Medicine and Haematology, Zebrafish, Nonmammalian, Caspase 3, INDUCTION, Gene Expression Regulation, Developmental, Hematology, APOPTOSIS, Medicine, Research & Experimental, Embryo, Glycoproteins - administration & dosage, Caspases, Intercellular Signaling Peptides and Proteins, Intercellular Signaling Peptides and Proteins - administration & dosage, 3201 Cardiovascular medicine and haematology, Life Sciences & Biomedicine, Developmental - drug effects, Morpholines, Apoptosis - drug effects, Immunology, Hemoglobins - biosynthesis - drug effects, Gene Expression Regulation, Developmental - drug effects, Animals, Glycoproteins, Science & Technology, Animal, MESODERM, Hematopoiesis, Disease Models, Animal, Gene Expression Regulation, TRANSGENIC ZEBRAFISH, Disease Models, CELLS, ERYTHROPOIESIS, Hematopoiesis - drug effects - genetics - physiology
Caspases - drug effects - metabolism, Embryo, Nonmammalian, Receptors, Tumor Necrosis Factor - administration & dosage - genetics - metabolism, Apoptosis, Research & Experimental Medicine, Receptors, Tumor Necrosis Factor, Hemoglobins, Receptors, Zebrafish - embryology - genetics - metabolism, BMP-4, Tumor Necrosis Factor - administration & dosage - genetics - metabolism, Morpholines - administration & dosage, 1102 Cardiorespiratory Medicine and Haematology, Zebrafish, Nonmammalian, Caspase 3, INDUCTION, Gene Expression Regulation, Developmental, Hematology, APOPTOSIS, Medicine, Research & Experimental, Embryo, Glycoproteins - administration & dosage, Caspases, Intercellular Signaling Peptides and Proteins, Intercellular Signaling Peptides and Proteins - administration & dosage, 3201 Cardiovascular medicine and haematology, Life Sciences & Biomedicine, Developmental - drug effects, Morpholines, Apoptosis - drug effects, Immunology, Hemoglobins - biosynthesis - drug effects, Gene Expression Regulation, Developmental - drug effects, Animals, Glycoproteins, Science & Technology, Animal, MESODERM, Hematopoiesis, Disease Models, Animal, Gene Expression Regulation, TRANSGENIC ZEBRAFISH, Disease Models, CELLS, ERYTHROPOIESIS, Hematopoiesis - drug effects - genetics - physiology
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