title: Expression of the somatolactin beta gene during zebrafish embryonic development.
abstract: Somatolactin (Sl) is a pituitary hormone closely related to prolactin (Prl) and growth hormone that was until now only found in various fish species. We isolated the cDNA coding for zebrafish Slbeta and we identified the gene encoding this hormone. We also obtained a 1kb genomic fragment corresponding to the slbeta upstream promoter region. Furthermore, the slbeta expression pattern was examined during zebrafish embryogenesis using whole-mount in situ hybridization. Slbeta mRNA is first detected in a single cell at the anterior border of the neural plate starting at 23h post fertilization (hpf). Slbeta-expressing cells also express the transcription factor pit1 and are located close to prl-expressing cells. Using combined fluorescent in situ hybridization, we show that slbeta- and prl-expressing cells are clearly distinct at 29 hpf. Starting at 30 hpf, the number of slbeta positive cells increases and their location becomes more clearly distinct from lactotrope cells, in a more posterior position. At later stages (48 hpf), slbeta expression was observed posterior to growth hormone expression, again in a distinct cell type. We show that zebrafish mutants aal, as well as mutants in the pit1 gene, are deficient in slbeta expression. In conclusion, slbeta expression defines a new, additional cell type in zebrafish pituitary that depends on pit1 and aal for its differentiation.
authors.affiliation: Laboratory for Molecular Biology and Genetic Engineering, Institut de Chimie, Bât. B6, Université of Liège, B-4000 Liège, Sart-Tilman, Belgium.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Lopez
authors.forename: Gabriela
authors.initials: G
authors.lastname: Nica
authors.forename: Patrick
authors.initials: P
authors.lastname: Motte
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Martial
authors.forename: Matthias
authors.initials: M
authors.lastname: Hammerschmidt
authors.forename: Marc
authors.initials: M
authors.lastname: Muller
mesh_terms: D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000235:genetics*; D013006:Growth Hormone / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D009154:Mutation; D010902:Pituitary Gland / Q000196:embryology / Q000378:metabolism; D010907:Pituitary Hormones / Q000235:genetics*; D011388:Prolactin / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D029941:Fish Proteins; D006023:Glycoproteins; D010907:Pituitary Hormones; D012333:RNA, Messenger; C064448:somatolactin protein, fish; D011388:Prolactin; D013006:Growth Hormone