CORRECTION OF ABNORMAL RETINAL PATHWAYS FOUND WITH ALBINISM BY INTRODUCTION OF A FUNCTIONAL TYROSINASE GENE IN TRANSGENIC MICE

In albino mammals the pattern of connections between the eye and the b rain is systematically disrupted at the optic chiasm, with a proportio n of axons that should project ipsilaterally being rerouted to the con tralateral hemisphere of the brain. Albino mice carry a mutation at th e c-locus, which encodes the tyrosinase gene. Tyrosinase is the key en zyme in melanin synthesis. In this study we have used transgenic mice generated from an albino strain in which a functional tyrosinase trans gene within a yeast artificial chromosome has been inserted. We have e xamined the chiasmatic pathways in these and control animals and have demonstrated that the abnormality is corrected in the tyrosinase trans genic mice. The results of this study identify the key element in this abnormality. The establishment of the transgenic model provides a uni que tool with which to investigate the way in which melanin shapes thi s region of the developing mammalian visual system. (C) 1993 Academic Press,Inc.