title: Generation of BAC transgenic tadpoles enabling live imaging of motoneurons by using the urotensin II-related peptide (ust2b) gene as a driver.
abstract: Xenopus is an excellent tetrapod model for studying normal and pathological motoneuron ontogeny due to its developmental morpho-physiological advantages. In mammals, the urotensin II-related peptide (UTS2B) gene is primarily expressed in motoneurons of the brainstem and the spinal cord. Here, we show that this expression pattern was conserved in Xenopus and established during the early embryonic development, starting at the early tailbud stage. In late tadpole stage, uts2b mRNA was detected both in the hindbrain and in the spinal cord. Spinal uts2b+ cells were identified as axial motoneurons. In adult, however, the uts2b expression was only detected in the hindbrain. We assessed the ability of the uts2b promoter to drive the expression of a fluorescent reporter in motoneurons by recombineering a green fluorescent protein (GFP) into a bacterial artificial chromosome (BAC) clone containing the entire X. tropicalis uts2b locus. After injection of this construction in one-cell stage embryos, a transient GFP expression was observed in the spinal cord of about a quarter of the resulting animals from the early tailbud stage and up to juveniles. The GFP expression pattern was globally consistent with that of the endogenous uts2b in the spinal cord but no fluorescence was observed in the brainstem. A combination of histological and electrophysiological approaches was employed to further characterize the GFP+ cells in the larvae. More than 98% of the GFP+ cells expressed choline acetyltransferase, while their projections were co-localized with α-bungarotoxin labeling. When tail myotomes were injected with rhodamine dextran amine crystals, numerous double-stained GFP+ cells were observed. In addition, intracellular electrophysiological recordings of GFP+ neurons revealed locomotion-related rhythmic discharge patterns during fictive swimming. Taken together our results provide evidence that uts2b is an appropriate driver to express reporter genes in larval motoneurons of the Xenopus spinal cord.
authors: Evolution des Régulations Endocriniennes, UMR 7221 CNRS, Muséum National d'Histoire Naturelle, Paris, France.
authors: Marion
authors: M
authors: Bougerol
authors: UPMC/INSERM UMRS 974, CNRS FRE 3617, AIM, Paris, France; INSERM, Avenir Team, Pitié-Salpêtrière, Paris, France.
authors: Frédéric
authors: F
authors: Auradé
authors: UMR 5287 CNRS, Université de Bordeaux, INCIA, Bordeaux, France.
authors: François M
authors: FM
authors: Lambert
authors: UMR 5287 CNRS, Université de Bordeaux, INCIA, Bordeaux, France.
authors: Didier
authors: D
authors: Le Ray
authors: UMR 5287 CNRS, Université de Bordeaux, INCIA, Bordeaux, France.
authors: Denis
authors: D
authors: Combes
authors: UMR 5287 CNRS, Université de Bordeaux, INCIA, Bordeaux, France.
authors: Muriel
authors: M
authors: Thoby-Brisson
authors: UPMC/INSERM UMRS 974, CNRS FRE 3617, AIM, Paris, France; INSERM, Avenir Team, Pitié-Salpêtrière, Paris, France.
authors: Frédéric
authors: F
authors: Relaix
authors: Institute of Systems and Synthetic Biology, CNRS, Université d'Evry Val d'Essonne, Evry, France.
authors: Nicolas
authors: N
authors: Pollet
authors: Evolution des Régulations Endocriniennes, UMR 7221 CNRS, Muséum National d'Histoire Naturelle, Paris, France.
authors: Hervé
authors: H
authors: Tostivint
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000378:metabolism; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics / Q000378:metabolism*; D055724:Electrophysiological Phenomena; D004625:Embryo, Nonmammalian / Q000378:metabolism; D017930:Genes, Reporter; D017403:In Situ Hybridization; D008856:Microscopy, Fluorescence; D009046:Motor Neurons / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism; D014579:Urotensins / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010455:Peptides; D014579:Urotensins; C029677:urotensin II