Tissue interactions and lens-forming competence in the outer cornea of larval Xenopus laevis. 2003

Stefano M Cannata, and Emiliano Arresta, and Sergio Bernardini, and Cesare Gargioli, and Sergio Filoni
Department of Biology, Tor Vergata University, Rome, Italy.

After lentectomy through the pupillary hole, the outer cornea of larval Xenopus laevis can undergo transdifferentiation to regenerate a new lens. This process is elicited by inductive factor(s) produced by the neural retina and accumulated into the vitreous chamber. During embryogenesis, the outer cornea develops from the outer layer of the presumptive lens ectoderm (PLE) under the influence of the eye cup and the lens. In this study, we investigated whether the capacity of the outer cornea to regenerate a lens is the result of early inductive signals causing lens-forming bias and lens specification of the PLE, or late inductive signals causing cornea formation or both signals. Fragments of larval epidermis or cornea developed from ectoderm that had undergone only one kind of inductive signals, or both kinds of signals, or none of them, were implanted into the vitreous chamber of host larvae. The regeneration potential and the lens-forming transformations of the implants were tested using an antisense probe for pax6 as an earlier marker of lens formation and a monoclonal antibody anti-lens as a definitive indicator of lens cell differentiation. Results demonstrated that the capacity of the larval outer cornea to regenerate a lens is the result of both early and late inductive signals and that either early inductive signals alone or late inductive signals alone can elicit this capacity.

UI MeSH Term Description Entries
D007814 Larva Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals. Maggots,Tadpoles,Larvae,Maggot,Tadpole
D007908 Lens, Crystalline A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION. Eye Lens,Lens, Eye,Crystalline Lens
D012038 Regeneration The physiological renewal, repair, or replacement of tissue. Endogenous Regeneration,Regeneration, Endogenous,Regenerations
D012097 Repressor Proteins Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release. Repressor Molecules,Transcriptional Silencing Factors,Proteins, Repressor,Silencing Factors, Transcriptional
D003315 Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed) Corneas
D004475 Ectoderm The outer of the three germ layers of an embryo. Apical Ectodermal Ridge,Apical Ectodermal Ridges,Ectodermal Ridge, Apical,Ectoderms
D004817 Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).
D005136 Eye Proteins PROTEINS derived from TISSUES of the EYE. Proteins, Eye
D000071841 PAX6 Transcription Factor A paired box transcription factor that has important functions in the development of the eye, nose, central nervous system and pancreas. Mutations in the PAX6 gene are associated with ocular disorders such as ANIRIDIA. Aniridia Type II Protein,Oculorhombin,PAX6 Protein,Paired Box Gene 6 Protein,Paired Box Protein Pax-6,Paired Box Transcription Factor 6,Pax-6 Protein,Pax6.1 Protein,Pax6.2 Protein,Transcription Factor PAX6,Factor PAX6, Transcription,Factor, PAX6 Transcription,PAX6, Transcription Factor,Paired Box Protein Pax 6,Pax 6 Protein,Protein, PAX6,Protein, Pax-6,Protein, Pax6.1,Protein, Pax6.2,Transcription Factor, PAX6
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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