title: The Xenopus homologue of the Drosophila gene tailless has a function in early eye development.
abstract: Genetic circuits responsible for the development of photoreceptive organs appear to be evolutionarily conserved. Here, the Xenopus homologue Xtll of the Drosophila gene tailless (tll), which we find to be expressed during early eye development, is characterized with respect to its relationship to vertebrate regulators of eye morphogenesis, such as Pax6 and Rx. Expression of all three genes is first detected in the area corresponding to the eye anlagen within the open neural plate in partially overlapping, but not identical, patterns. During the evagination of the optic vesicle, Xtll expression is most prominent in the optic stalk, as well as in the distal tip of the forming vesicle. In tadpole-stage embryos, Xtll gene transcription is most prominent in the ciliary margin of the optic cup. Inhibition of Xtll function in Xenopus embryos interferes specifically with the evagination of the eye vesicle and, in consequence, Xpax6 gene expression is severely reduced in such manipulated embryos. These findings suggest that Xtll serves an important regulatory function in the earliest phases of vertebrate eye development.
authors.affiliation: Institut für Biochemie und Molekulare Zellbiologie, Humboldtallee 23, D-37073 Göttingen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Hollemann
authors.forename: E
authors.initials: E
authors.lastname: Bellefroid
authors.forename: T
authors.initials: T
authors.lastname: Pieler
mesh_terms: D000375:Aging; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000502:physiology*; D004627:Embryonic Induction; D019143:Evolution, Molecular; D005123:Eye / Q000196:embryology* / Q000254:growth & development; D005136:Eye Proteins / Q000096:biosynthesis; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009865:Oocytes / Q000502:physiology; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000737:chemistry / Q000502:physiology*; D012097:Repressor Proteins / Q000096:biosynthesis / Q000502:physiology; D016415:Sequence Alignment; D014981:Xenopus; D029867:Xenopus Proteins
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; C490259:NR2E1 protein, Xenopus; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D018160:Receptors, Cytoplasmic and Nuclear; D012097:Repressor Proteins; C074090:TLL protein, Drosophila; D029867:Xenopus Proteins