Andreas Fritz

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The otic placode is a transient embryonic structure that gives rise to the inner ear. Although inductive signals for otic placode formation have been characterized, less is known about the molecules that respond to these signals within otic primordia. Here, we identify a mutation in zebrafish, hearsay, which disrupts the initiation of placode formation. We(More)
Sensory placodes are ectodermal thickenings that give rise to elements of the vertebrate cranial sensory nervous system, including the inner ear and nose. Although mutations have been described in humans, mice and zebrafish that perturb ear and nose development, no mutation is known to prevent sensory placode formation. Thus, it has been postulated that a(More)
Segmentation of a vertebrate embryo begins with the subdivision of the paraxial mesoderm into somites through a not-well-understood process. Recent studies provided evidence that the Notch-Delta and the FGFR (fibroblast growth factor receptor) signalling pathways are required for segmentation. In addition, the Mesp family of bHLH transcription factors have(More)
We cloned and characterized the Drosophila homolog of mammalian Jun-N-terminal kinases (DJNK). We show that DJNK is encoded by basket (bsk). Like hemipterous (hep), which encodes the Drosophila JNK kinase, bsk is required in the embryo for dorsal closure, a process involving coordinate cell shape changes of ectodermal cells. Dorsal closure can also be(More)
The formation of the otic placode is a complex process requiring multiple inductive signals. In zebrafish, fgf3 and fgf8, dlx3b and dlx4b, and foxi1 have been identified as the earliest-acting genes in this process. fgf3 and fgf8 are required as inductive signals, whereas dlx3b, dlx4b, and foxi1 appear to act directly within otic primordia. We have(More)
BACKGROUND Fate mapping studies have shown that progenitor cells of three vertebrate embryonic midline structures - the floorplate in the ventral neural tube, the notochord and the dorsal endoderm - occupy a common region prior to gastrulation. This common region of origin raises the possibility that interactions between midline progenitor cells are(More)
Vertebrate Pax2 and Pax8 proteins are closely related transcription factors hypothesized to regulate early aspects of inner ear development. In zebrafish and mouse, Pax8 expression is the earliest known marker of otic induction, and Pax2 homologs are expressed at slightly later stages of placodal development. Analysis of compound mutants has not been(More)
The vertebrate inner ear arises from the otic placode, a transient thickening of ectodermal epithelium adjacent to neural crest domains in the presumptive head. During late gastrulation, cells fated to comprise the inner ear are part of a domain in cranial ectoderm that contain precursors of all sensory placodes, termed the preplacodal region (PPR). The(More)
We have identified three novel members of the zebrafish forkhead class I gene family, which we have named foxi2, foxi3a, and foxi3b. We have reported previously the identification of zebrafish foxi1, which is required for otic placode and jaw development. Expression analysis shows that foxi2 is expressed within the chordamesoderm during early somitogenesis(More)
We describe a novel hereditary cancer syndrome in the rat that is transmitted by a recessive gene mutation. Animals exhibiting the mutant phenotype develop multiple neuroendocrine malignancies within the first year of life. The endocrine neoplasia is characterized by bilateral adrenal pheochromocytoma, multiple extra-adrenal pheochromocytoma, bilateral(More)