Conditional inactivation of nodal signaling reveals critical period in eye development
Gay, Steven Alexander
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Holoprosencephaly is a congenital disorder that affects roughly 1 out of 5,000-10,000 human births and 1 out of 200 spontaneous abortions. It is characterized by the failure of the embryonic prosencephalon to divide into two cerebral hemispheres, known as the diencephalon. This is accompanied by mental retardation and facial deformities, including cyclopia in severe cases. Previous studies implicate aberrantly low gene expression of Sonic hedgehog as a cause for this disorder. The aim of this study is to utilize a pharmaceutical approach using the drug SB-505124 which knocks down nodal activity, a known inducer of Sonic hedgehog expression. The results indicate that the absence of nodal activity in the zebrafish developmental window of 70% epiboly to 90% epiboly causes severe holoprosencephaly, cyclopia, and restriction of the Zona limitans intrathalamica in the forebrain, as well as other defects.