Neuhauss Stephan C F, Seeliger Mathias W, Schepp Carsten P, Biehlmaier Oliver
Brain Research Institute, University of Zurich and Department of Biology, Swiss Federal Institute of Technology Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland.
Doc Ophthalmol. 2003 Jul;107(1):71-8. doi: 10.1023/a:1024492029629.
The recessive zebrafish mutant bleached has, apart from its defects in pigmentation, a heritable defect leading to larval blindness. Here, we analyze the retina of homozygous bleached larvae, employing morphological and electrophysiological methods. Electroretinography revealed a complete lack of electrical signals in response to light. Histological analysis of mutant retinae showed a severely affected outer retina with a hypopigmented pigment epithelium and a disorganized outer nuclear layer containing few or no intact photoreceptors. Using the TUNEL assay for cell death detection, we noticed a strong increase of apoptotic cells in all retinal cell layers, starting in young larvae even before retinal support of visual function. At later stages cell death is most pronounced at the marginal zone, where new cells are constantly added to the retina. At early stages increased apoptosis is mainly confined to the retina, while at later stages elevated cell death is al so apparent in extra-retinal tissues, particularly in the brain. Hence, the lack of visual responses in homozygous bleached larvae can be attributed to a severe defect of the outer retina, preceded by increased levels of apoptotic cell death in all retinal cell layers.
隐性斑马鱼突变体“白化”除了色素沉着缺陷外，还有一种导致幼虫失明的遗传缺陷。在此，我们采用形态学和电生理学方法分析纯合“白化”幼虫的视网膜。视网膜电图显示对光无电信号反应。突变体视网膜的组织学分析表明，外部视网膜严重受损，色素上皮色素减退，外核层紊乱，几乎没有或没有完整的光感受器。使用TUNEL法检测细胞死亡，我们注意到所有视网膜细胞层的凋亡细胞大量增加，甚至在幼虫早期视觉功能得到视网膜支持之前就已开始。在后期，细胞死亡在边缘区最为明显，新细胞不断添加到视网膜中。在早期，凋亡增加主要局限于视网膜，而在后期，细胞死亡增加在视网膜外组织中也很明显，尤其是在大脑中。因此，纯合“白化”幼虫缺乏视觉反应可归因于外部视网膜的严重缺陷，在此之前所有视网膜细胞层的凋亡细胞死亡水平都有所增加。
