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Abstract：
Vertebrate eye formation requires coordinated inductive interactions between different embryonic tissue layers, first described in amphibians. A network of transcription factors and signaling molecules controls these steps, with mutations causing severe ocular, neuronal, and craniofacial defects. In eyeless mutant axolotls, eye morphogenesis arrests at the optic vesicle stage, before lens induction, and development of ventral forebrain structures is disrupted.
We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species.
The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
We identified a 5-bp deletion in the rax (retina and anterior neural fold homeobox) gene, which was tightly linked to the recessive eyeless (e) axolotl locus in an F2 cross. This frameshift mutation, in exon 2, truncates RAX protein within the homeodomain (P154fs35X). Quantitative RNA analysis shows that mutant and wild-type rax transcripts are equally abundant in E/e embryos. Translation appears to initiate from dual start codons, via leaky ribosome scanning, a conserved feature among gnathostome RAX proteins. Previous data show rax is expressed in the optic vesicle and diencephalon, deeply conserved among metazoans, and required for eye formation in other species.
The eyeless axolotl mutation is a null allele in the rax homeobox gene, with primary defects in neural ectoderm, including the retinal and hypothalamic primordia.
摘要：
脊椎动物眼的形成需要不同胚胎组织层之间协调的感应相互作用，首先在两栖动物中描述。转录因子和信号分子的网络控制着这些步骤，突变导致严重的眼部，神经元，和颅面缺陷。在无眼突变的axolotls中，眼睛形态发生在视神经囊泡阶段，在透镜感应之前，腹侧前脑结构的发育被破坏。
我们在rax（视网膜和前神经折叠同源框）基因中发现了一个5bp的缺失，与F2杂交中的隐性无眼（e）axolotl基因座紧密相关。这个移码突变,在外显子2中，截短同源结构域内的RAX蛋白（P154fs35X）。定量RNA分析表明，突变和野生型rax转录本在E/e胚胎中同样丰富。翻译似乎是从双启动密码子开始的，通过泄漏核糖体扫描，颌骨茎RAX蛋白中的保守特征。以前的数据显示rax在视神经囊泡和间脑中表达，在后生动物中非常保守，并且是其他物种眼睛形成所必需的。
无眼axolotl突变是rax同源异型框基因中的无效等位基因，神经外胚层的主要缺陷，包括视网膜和下丘脑原基.
我们在rax（视网膜和前神经折叠同源框）基因中发现了一个5bp的缺失，与F2杂交中的隐性无眼（e）axolotl基因座紧密相关。这个移码突变,在外显子2中，截短同源结构域内的RAX蛋白（P154fs35X）。定量RNA分析表明，突变和野生型rax转录本在E/e胚胎中同样丰富。翻译似乎是从双启动密码子开始的，通过泄漏核糖体扫描，颌骨茎RAX蛋白中的保守特征。以前的数据显示rax在视神经囊泡和间脑中表达，在后生动物中非常保守，并且是其他物种眼睛形成所必需的。
无眼axolotl突变是rax同源异型框基因中的无效等位基因，神经外胚层的主要缺陷，包括视网膜和下丘脑原基.
