ZEBRAFISH RADAR - A NEW MEMBER OF THE TGF-BETA SUPERFAMILY DEFINES DORSAL REGIONS OF THE NEURAL PLATE AND THE EMBRYONIC RETINA

Proper development of metazoan embryos requires cell to cell communica tions. In many instances, these communications involve diffusible mole cules, particularly members of the Transforming Growth Factor P superf amily. In an effort to identify new members of this superfamily involv ed in the control of early zebrafish embryogenesis, we have isolated a gene, Radar, which appears to be conserved throughout vertebrate evol ution and defines a new subfamily within the superfamily. Its pattern of expression suggests that Radar plays a role in the dorso-ventral po larity of the neural plate, blood islands formation, blood cells diffe rentiation, the establishment of retinal dorso-ventral polarity and/or proper axonal retinotectal projections. Radar expression in ntl homoz ygous mutants indicates that notochord and hypochord development are i ntimately linked.