Relationship between crystallin mRNA expression in retina cells and their capacity to re-differentiate into lens cells.

Differentiating vertebrate embryo tissues pass through a stage when they have the potential for several pathways of differentiation, some of them revealed only by experimental manoeuvres. As differentiation proceeds, the potential for alternative pathways becomes progressively restricted and is eventually lost. We have investigated the molecular basis for this phenomenon, using the chick embryo retina, which has a potential for differentiation into lens cells. This potential requires special conditions for its manifestation; it declines during development and is finally lost before hatching. Lens protein (crystallin) mRNA is expressed in early embryo retina: its levels decline in parallel with the decline in lens-forming potential. There is also evidence of an ontogenic change in post-transcriptional regulation. Such a relationship between heterologous mRNA and heterologous differentiation potential may be of general application.