Chandrasekhar A, Warren J T, Takahashi K, Schauerte H E, van Eeden F J, Haffter P, Kuwada J Y
Department of Biology, University of Michigan, 830 N. University, Ann Arbor, MI 48109-1048, USA.
Mech Dev. 1998 Aug;76(1-2):101-15. doi: 10.1016/s0925-4773(98)00101-4.
The role of zebrafish hedgehog genes in branchiomotor neuron development was analyzed by examining mutations that affect the expression of the hedgehog genes and by overexpressing these genes in embryos. In cyclops mutants, reduction in sonic hedgehog (shh) expression, and elimination of tiggy-winkle hedgehog (twhh) expression, correlated with reductions in branchiomotor neuron populations. Furthermore, branchiomotor neurons were restored in cyclops mutants when shh or twhh was overexpressed. These results suggest that Shh and/or Twhh play an important role in the induction of branchiomotor neurons in vivo. In sonic-you (syu) mutants, where Shh activity was reduced or eliminated due to mutations in shh, branchiomotor neurons were reduced in number in a rhombomere-specific fashion, but never eliminated. Similarly, spinal motor neurons were reduced, but not eliminated, in syu mutants. These results demonstrate that Shh is not solely responsible for inducing branchiomotor and spinal motor neurons, and suggest that Shh and Twhh may function as partially redundant signals for motor neuron induction in zebrafish.
通过检测影响刺猬基因表达的突变以及在胚胎中过表达这些基因，分析了斑马鱼刺猬基因在鳃运动神经元发育中的作用。在独眼畸形突变体中，音猬因子（shh）表达减少，而刺猬索尼克（twhh）表达缺失，这与鳃运动神经元数量减少相关。此外，当shh或twhh过表达时，独眼畸形突变体中的鳃运动神经元得以恢复。这些结果表明，Shh和/或Twhh在体内鳃运动神经元的诱导中起重要作用。在音猬因子缺陷（syu）突变体中，由于shh突变导致Shh活性降低或缺失，鳃运动神经元数量以一种特定菱脑节的方式减少，但从未完全缺失。同样，syu突变体中的脊髓运动神经元数量减少，但未完全缺失。这些结果表明，Shh并非单独负责诱导鳃运动神经元和脊髓运动神经元，提示Shh和Twhh可能作为斑马鱼运动神经元诱导的部分冗余信号发挥作用。
