RT Journal Article SR Electronic T1 The zebrafish epiboly mutants JF Development JO Development FD The Company of Biologists Limited SP 47 OP 55 VO 123 IS 1 A1 Kane, D.A. A1 Hammerschmidt, M. A1 Mullins, M.C. A1 Maischein, H.M. A1 Brand, M. A1 van Eeden, F.J. A1 Furutani-Seiki, M. A1 Granato, M. A1 Haffter, P. A1 Heisenberg, C.P. A1 Jiang, Y.J. A1 Kelsh, R.N. A1 Odenthal, J. A1 Warga, R.M. A1 Nusslein-Volhard, C. YR 1996 UL http://dev.biologists.org/content/123/1/47.abstract AB Epiboly, the enveloping of the yolk cell by the blastoderm, is the first zebrafish morphogenetic movement. We isolated four mutations that affect epiboly: half baked, avalanche, lawine and weg. Homozygous mutant embryos arrest the vegetal progress of the deep cells of the blastoderm; only the yolk syncytial layer of the yolk cell and the enveloping layer of the blastoderm reach the vegetal pole of the embryo. The mutations half baked, avalanche and lawine produce a novel dominant effect, termed a zygotic-maternal dominant effect: heterozygous embryos produced from heterozygous females slow down epiboly and accumulate detached cells over the neural tube; a small fraction of these mutant individuals are viable. Heterozygous embryos produced from heterozygous males crossed to homozygous wild-type females complete epiboly normally and are completely viable. Additionally, embryos heterozygous for half baked have an enlarged hatching gland, a partial dominant phenotype. The phenotypes of these mutants demonstrate that, for the spreading of cells during epiboly, the movement of the deep cells of the blastoderm require the function of genes that are not necessary for the movement of the enveloping layer or the yolk cell. Furthermore, the dominant zygotic-maternal effect phenotypes illustrate the maternal and zygotic interplay of genes that orchestrate the early cell movements of the zebrafish.