title: bloodthirsty, an RBCC/TRIM gene required for erythropoiesis in zebrafish.
abstract: The Antarctic icefishes (family Channichthyidae, suborder Notothenioidei) constitute the only vertebrate taxon that fails to produce red blood cells. These fishes can be paired with closely related, but erythrocyte-producing, notothenioids to discover erythropoietic genes via representational difference analysis. Using a B30.2-domain-encoding DNA probe so derived from the hematopoietic kidney (pronephros) of a red-blooded Antarctic rockcod, Notothenia coriiceps, we discovered a related, novel gene, bloodthirsty (bty), that encoded a 547-residue protein that contains sequential RING finger, B Box, coiled-coil, and B30.2 domains. bty mRNA was expressed by the pronephric kidney of N. coriiceps at a steady-state level 10-fold greater than that found in the kidney of the icefish Chaenocephalus aceratus. To test the function of bty, we cloned the orthologous zebrafish gene from a kidney cDNA library. Whole-mount in situ hybridization of zebrafish embryos showed that bty mRNA was present throughout development and, after the mid-blastula transition, was expressed in the head and in or near the site of primitive erythropoiesis in the tail just prior to red cell production. One- to four-cell embryos injected with two distinct antisense morpholino oligonucleotides (MOs) targeted to the 5'-end of the bty mRNA failed to develop red cells, whereas embryos injected with 4- and 5-bp mismatch control MOs produced wild-type quantities of erythrocytes. The morphant phenotype was rescued by co-injection of synthetic bty mRNA containing an artificial 5'-untranslated region (UTR) with the antisense MO that bound the 5'-UTR of the wild-type bty transcript. Furthermore, the expression of genes that mark terminal erythroid differentiation was greatly reduced in the antisense-MO-treated embryos. We conclude that bty is likely to play a role in differentiation of the committed red cell progenitor.
authors.affiliation: Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Yergeau
authors.forename: Catharine N
authors.initials: CN
authors.lastname: Cornell
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Parker
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.forename: H William
authors.initials: HW
authors.lastname: Detrich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D002454:Cell Differentiation; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000502:physiology*; D004920:Erythropoiesis / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014158:Transcription, Genetic; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D029961:Zebrafish Proteins; C503418:bty protein, zebrafish