Zebrafish deadly seven Functions in Neurogenesis

Abstract

In a genetic screen, we isolated a mutation that perturbed motor axon outgrowth, neurogenesis, and somitogenesis. Complementation tests revealed that this mutation is an allele of deadly seven (des). By creating genetic mosaics, we demonstrate that the motor axon defect is non-cell autonomous. In addition, we show that the pattern of migration for some neural crest cell populations is aberrant and crest-derived dorsal root ganglion neurons are misplaced. Furthermore, our analysis reveals that des mutant embryos exhibit a neurogenic phenotype. We find an increase in the number of primary motoneurons and in the number of three hindbrain reticulospinal neurons: Mauthner cells, RoL2 cells, and MiD3cm cells. We also find that the number of Rohon-Beard sensory neurons is decreased whereas neural crest-derived dorsal root ganglion neurons are increased in number supporting a previous hypothesis that Rohon-Beard neurons and neural crest form an equivalence group during development. Mutations in genes involved in Notch-Delta signaling result in defects in somitogenesis and neurogenesis. We found that overexpressing an activated form of Notch decreased the number of Mauthner cells in des mutants indicating that des functions via the Notch-Delta signaling pathway to control the production of specific cell types within the central and peripheral nervous systems.

HoxGene Misexpression and Cell-Specific Lesions Reveal Functionality of Homeotically Transformed Neurons

“…Our finding that startle behavior is not affected in zebrafish with ectopic Mauthner cells is consistent with previous work on zebrafish deadly seven mutants (des b420 and des tp37 ) (van Eeden et al, 1996), which develop up to eight Mauthner cells on each side of the hindbrain in rhombomere 4 (Gray et al, 2001). Liu et al (2003) found that in the des b420 , all M-cells appear to respond to startle stimuli, and they respond simultaneously, suggesting that they are receiving similar sensory input.…”

Insulin-like growth factor signaling regulates zebrafish embryonic growth and development by promoting cell survival and cell cycle progression

“…Whole mount BrdU analysis of proliferative cells was done according to Gray et al 40 Briefly, embryos were soaked in BrdU solution for 20 min, transferred to water lacking BrdU for 30 min, then fixed and stained with a 1 : 100 dilution of a BrdU antibody (Invitrogen, Carlsbad, CA, USA). A 1 : 500 dilution of a Cy3-conjugated secondary antibody (Jackson ImmunoResearch Laboratories, West Grove, PA, USA) was used to detect the primary antibodies.…”

Atoh1a expression must be restricted by Notch signaling for effective morphogenesis of the posterior lateral line primordium in zebrafish

“…The embryos were staged according to Kimmel et al (Kimmel et al, 1995). The mind bomb, mib ta52b , mib m132 , mib m178 (Itoh et al, 2003;Jiang et al, 1996), notch1a, deadly seven, des b420 (Gray et al, 2001) and tg [cldnb:lynGFP] (Hass et al,…”