An attempt to assay the state of determination by using transfected genes as probes in transdifferentiation of neural retina into lens.

Hybrid genes coding for chloramphenicol acetyltransferase (CAT) with a non-specific retroviral, lens-specific delta-crystallin or lens-specific alpha-crystallin promoters were constructed to transfect the transdifferentiating (lentoidogenic) and non-transdifferentiating (non-lentoidogenic) cultures of chicken embryonic neural retina for assaying the state of determination towards lens differentiation. The expression occurred only when CAT genes with lens-specific promoters were transfected to the cultures maintained in the conditions permissive to lentoidogenesis. The expression of these exogenous, lens-specific CAT genes began at stages of culturing that were earlier than the expression of endogenous crystallin. Presumably, there are two steps in the transdifferentiation of neural retina into lens; acquisition of capacity to express crystallin genes and derepression of the endogenous crystallin genes.