Elsevier

Developmental Biology

Volume 270, Issue 2, 15 June 2004, Pages 336-349
Developmental Biology

Zebrafish rx3 and mab21l2 are required during eye morphogenesis

https://doi.org/10.1016/j.ydbio.2004.02.026Get rights and content
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Abstract

Two alleles of an eyeless mutant, chokh (chk), were identified in ongoing zebrafish F3 mutagenesis screens. Morphologically, chk mutants can be identified at 15 h post-fertilization by the failure of optic primordia to evaginate from the forebrain. The chk phenotype appears specific, as marker genes in the forebrain, midbrain, and pineal are expressed in normal temporal, spatial, and circadian patterns. Sequence analysis of the chk alleles revealed nonsense or missense mutations in the rx3 homeobox. Rx genes encode paired-type homeodomain transcription factors known to be key regulators of eye development in mouse, medaka, Xenopus, and zebrafish. To uncover novel Rx targets, we analyzed the expression of multiple eye development genes in chk. We find that expression of mab21l2, mab21l1 and rx2 are specifically absent in the eye field of chk embryos. Knockdown of Mab21l2 by antisense morpholino microinjections partially phenocopies the rx3 mutation, leading to microphthalmia, incomplete eye maturation, and dramatic increases in apoptotic eye progenitors. We propose that mab21l2 is an early downstream effector of rx3 and is critical for survival of eye progenitors.

Keywords

Zebrafish
Eye development
Retinal homeobox
mab21l2
Mutagenesis
Retinal progenitor

Abbreviations

dpf
days post fertilization
Rx
retinal homeobox
WT
wild-type
(chk)
chokh
RPC
retinal progenitor cell

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