The zinc-finger gene manx is expressed during gastrulation in these hybrid embryos. This suggests that manx is required for tail and otolith formation during ascidian embryogenesis, and is a case of a single gene disruption resulting in a completely altered larval phenotype that is not lethal in nature. Novel genes expressed differentially in ascidians with alternate modes of development. Requirement of the manx gene for expression of chordate features in a tailless ascidian larva. A multigene locus containing the manx and bobcat genes is required for development of chordate features in the ascidian tadpole larva.
Urochordates are monophyletic within the deuterostomes.
Tunicates have unusual nuclear lamins with a large deletion in the carboxyterminal tail domain. Davidson, B., Jacobs, M. and Swalla, B.J . In Modularity in Development and Evolution. Chapter 10, pp. New Insights into chordate origins from phylogenies, fossils and developmental gene expression.