title: Islet-1 immunoreactivity in the developing retina of Xenopus laevis.
abstract: The LIM-homeodomain transcription factor Islet1 (Isl1) has been widely used as a marker of neuronal differentiation in the developing visual system of different classes of vertebrates, including mammals, birds, reptiles, and fish. In the present study, we analyzed the spatial and temporal distribution of Isl1-immunoreactive cells during Xenopus laevis retinal development and its relation to the formation of the retinal layers, and in combination with different markers of cell differentiation. The earliest Isl1 expression appeared at St29-30 in the cell nuclei of sparse differentiating neuroblasts located in the vitreal surface of the undifferentiated retina. At St35-36, abundant Isl1-positive cells accumulated at the vitreal surface of the neuroepithelium. As development proceeded and through the postmetamorphic juveniles, Isl1 expression was identified in subpopulations of ganglion cells and in subsets of amacrine, bipolar, and horizontal cells. These data together suggest a possible role for Isl1 in the early differentiation and maintenance of different retinal cell types, and Isl1 can serve as a specific molecular marker for the study of retinal cell specification in X. laevis.
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Álvarez-Hernán
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain.
authors.forename: Ruth
authors.initials: R
authors.lastname: Bejarano-Escobar
authors.affiliation: Departamento de Biología Celular, Facultad de Biología, Universidad Complutense, Ciudad Universitaria, C/José Antonio Novais 12, 28040 Madrid, Spain.
authors.forename: Ruth
authors.initials: R
authors.lastname: Morona
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: González
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain.
authors.forename: Gervasio
authors.initials: G
authors.lastname: Martín-Partido
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Francisco-Morcillo
mesh_terms: D000818:Animals; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D060850:LIM-Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000196:embryology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism*
chemical_list: D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1