T. Gridley

Abstract: The Notch gene of Drosophila encodes a large transmembrane protein involved in cell fate determination during embryonic and larval development. This gene is evolutionarily conserved, and Notch homologs have been cloned from several vertebrate species. To examine the in vivo role of the Notch1 gene, a mouse homolog of Notch, a mutation was introduced by targeted disruption in embryonic stem cells, and these cells were used to generate mutant mice. Intercrosses of animals heterozygous for the Notch1 mutation yielded no live-born homozygous mutant offspring. Homozygous mutant embryos died before 11.5 days of gestation. Morphological and histological analysis of the homozygous mutant embryos indicated that pattern formation through the first nine days of gestation appeared largely normal. However, histological analysis of mutant embryos subsequent to this stage revealed widespread cell death. Death of mutant embryos did not appear to be attributable to defects in placentation or vascularization. Examination of the RNA expression pattern of the Notch2 gene, another Notch gene family member, indicated that it partially overlapped the Notch1 expression pattern. Genetic analysis of the Notch1 mutation also demonstrated that it was not allelic to a mouse mutation described previously, Danforth's short tail (Sd). These results demonstrate that the Notch1 gene plays a vital role during early postimplantation development in mice.

TL;DR: Data suggest that the Motch gene plays multiple roles in patterning and differentiation of the early postimplantation mouse embryo, which is similar to that of Drosophila.

TL;DR: It is shown that widespread ectopic expression of the Hoxa-1 (Hox 1.6) gene directed by a human beta-actin promoter in transgenic mice is embryolethal and produces abnormal phenotypes in a subset of domains primarily located in anterior regions, which suggest that ectopic Hoxb-1 expression can reorganize select regions of the developing hindbrain by inducing partial transformations of several rhombomere-4-like identity.

TL;DR: The Drosophila gene snail encodes a zinc-finger protein that is required zygotically for mesoderm formation and is expressed early in the mesodermal germ layer.

TL;DR: The isolation of cDNA clones encompassing the full-length coding sequence of Notch-1, a mouse homolog of Drosophila Notch, retains all of the conserved amino acid motifs of notch and the other vertebrate Notch homologs.