The ability of the retina to regenerate in amphibians, teleosts and embryonic chicks is a particularly striking example of central nervous system repair following traumatic damage. In chick, the source of new retinal neural precursor cells in the regenerative process has been identified as the retinal pigmented epithelium. However, with increasing development the pigmented epithelium of the chick embryo loses its ability to generate neuronal cells. To study molecular mechanisms underlying this transdifferentiation and loss of regenerative capacity, the embryonic chick pigmented epithelium will be studied in a tissue culture system. The role of the extracellular matrix molecules, laminin and basic fibroblast growth factor, on transdifferentiation will be studied. Neuronal cells will be identified with antibodies to neuron specific markers. In addition, the polymerase chain reaction will be used to determine whether the GAP-43 or neurofilament genes are expressed. It also will be determined whether pigmented epithelium loses its regenerative capacity in the in vitro system. In addition, the expression of neuronal phenotype will be studied in relation to the expression of two chick genes that are homologous to the neural determination genes of the achaete scute complexes that play a role in neural determination in the fruit fly. These studies have the potential for identifying genes that play a role in the determination, as well as the regeneration, of retina.
