||The specification of C. elegans male tail ray six identity is governed by a group of genes involving mab-21. These genes are arranged in a linear genetic pathway. Vertebrate orthologues of these genes were each identified to be involved in eye development. As an initial step towards ascertaining whether the genetic relationships previously characterized in C. elegans are conserved in vertebrate eye development, I documented these transcripts’s temporal and spatial expression in zebrafish embryos. Furthermore, I perturbed the endogenous transcripts level through over-expression of mab21/2. In my study, I found that smad1 was up-regulated in mab21/2 over-expressed embryos. SMAD1 is the downstream effector of BMP4 in the BMP4 signaling pathway, which is, among other things, responsible for the dorsal-ventral patterning of the neural tube. In addition, whole mount RNA-ISH was performed to investigate if these additional smad1 RNA were expressed outside of its normal domains. However, the level of mab21/2 over-expression was not strong enough to generate a detectable smad1 signal. Therefore, my initial results suggested a different genetic relationship between mab21/2 and smad1 in zebrafish than that found between mab-21 and sma-2/sma-4 in C. elegens.