Cas9-mediated excision of disrupts endoderm development, pharynx formation and oral-aboral patterning.

The mesoderm is a key novelty in animal evolution, although we understand little of how the mesoderm arose. , the founding member of the T-box gene family, is a key gene in chordate mesoderm development. However, the gene was present in the common ancestor of fungi and animals long before mesoderm appeared.

Expression of a lung developmental cassette in the adult and developing zebrafish swimbladder.

The presence of an air-filled organ (AO), either lungs or a swimbladder, is a defining character of the Osteichthyes (bony vertebrates, including tetrapods). Despite the functional and structural diversity of AOs, it was not previously known whether the same group of developmental regulatory genes are involved in the early development of both lungs and swimbladders. This study demonstrates that a suite of genes (Nkx2.

FGFR3 expression in Xenopus laevis.

We studied the expression of FGF receptor 3 (FGFR3) mRNA throughout early development of Xenopus laevis by RT-PCR and in situ hybridization. RT-PCR shows that FGFR3 mRNA is localized within the gastrula; regionalized staining is detected by the neural plate stage and continues throughout embryonic development. Strong expression is seen in developing neural structures, especially in the forebrain and hindbrain, including the developing eyes, and in lateral mesoderm.

Targeted expression of the dominant-negative FGFR4a in the eye using Xrx1A regulatory sequences interferes with normal retinal development.

Molecular analysis of vertebrate eye development has been hampered by the availability of sequences that can selectively direct gene expression in the developing eye. We report the characterization of the regulatory sequences of the Xenopus laevis Rx1A gene that can direct gene expression in the retinal progenitor cells. We have used these sequences to investigate the role of Fibroblast Growth Factor (FGF) signaling in the development of retinal cell types.

Cell surface proteins during early Xenopus development: analysis of cell surface proteins and total glycoproteins provides evidence for a maternal glycoprotein pool.

The populations of cell surface proteins and total glycoproteins were investigated in early Xenopus embryos through lectin staining, affinity binding of glycoproteins to lectins, and use of a succinimide ester to biotinylate cell surface molecules. Lectin staining shows that the egg is endowed with a thick layer of surface glycoprotein, and that glycoprotein is immediately detected on the newly formed membranes of nascent blastomeres. The amount of glycoprotein found in eggs and early embryos remains constant, and electrophoretic analysis reveals no changes in abundant lectin-binding glycoproteins through the neurula stage.