Isolation of developmental mutants of the ascidian Ciona savignyi

Ascidians have been used extensively as model animals for experimental embr yology. We report here the results of a pilot study with the aim of develop ing genetic methods for the ascidian Ciona savignyi. The chemical mutagen N -ethyl-N-nitrosourea (ENU) was used to induce point mutations. Fl animals, produced by using sperm from ENU-treated animals to fertilize untreated egg s, were grown to reproductive age. Sperm and eggs collected from the hermap hrodite Fl adults were used to generate self-fertilized F2 broods, which we re then screened for recessive, zygotically acting mutations. Animals carry ing potential mutations were outcrossed to wild type to test for the herita bility of the phenotypes. We report on a number of mutants isolated using t his method, including several with abnormalities in tail and notochord deve lopment.