Akimenko M A, Ekker M, Wegner J, Lin W, Westerfield M
Loeb Institute for Medical Research, Ottawa, Ontario, Canada.
J Neurosci. 1994 Jun;14(6):3475-86. doi: 10.1523/JNEUROSCI.14-06-03475.1994.
We describe analysis of zebrafish distal-less-related homeobox genes that may serve as specifiers of positional information in anterior regions of the CNS and in peripheral structures. We isolated three zebrafish genes, dlx2, dlx3, and dlx4, by screening embryonic cDNA libraries. Comparisons of the predicted sequences of the Dlx2, Dlx3, and Dlx4 proteins with distal-less proteins from other species suggest that vertebrate distal-less genes can be divided into four orthologous groups. We observed similarities but also unique features of the expression patterns of the zebrafish dlx genes. Among the three genes, dlx3 alone is expressed during gastrulation. Shortly after gastrulation, cells in the ventral forebrain rudiment express dlx2 and dlx4, but not dlx3, and hindbrain neural crest cells express only dlx2. Presumptive precursor cells of the olfactory placodes express dlx3 and dlx4 but not dlx2. Transcripts of dlx3 and dlx4 are present in overlapping subsets of cells in the auditory vesicle and in cells of the median fin fold, whereas dlx2 is never expressed in the auditory vesicle and only at low levels in localized regions of the median fin fold. Cells of the visceral arches and their primordia express all three dlx genes, but with different developmental time courses. We suggest that combinatorial expression of the dlx genes is part of a homeobox gene code specifying pattern formation or cell fate determination in the forebrain, in peripheral structures of the head, and in the fins.
我们描述了对斑马鱼远端缺失相关同源框基因的分析，这些基因可能在中枢神经系统前部区域和外周结构中作为位置信息的指定因子。我们通过筛选胚胎cDNA文库分离出了三个斑马鱼基因，即dlx2、dlx3和dlx4。将Dlx2、Dlx3和Dlx4蛋白的预测序列与其他物种的远端缺失蛋白进行比较表明，脊椎动物远端缺失基因可分为四个直系同源组。我们观察到斑马鱼dlx基因表达模式既有相似性也有独特特征。在这三个基因中，只有dlx3在原肠胚形成期表达。原肠胚形成后不久，腹侧前脑原基中的细胞表达dlx2和dlx4，但不表达dlx3，而后脑神经嵴细胞仅表达dlx2。嗅基板的假定前体细胞表达dlx3和dlx4，但不表达dlx2。dlx3和dlx4的转录本存在于听泡细胞和正中鳍褶细胞的重叠亚群中，而dlx2在听泡中从不表达，仅在正中鳍褶的局部区域低水平表达。内脏弓及其原基的细胞表达所有三个dlx基因，但发育时间进程不同。我们认为，dlx基因的组合表达是同源框基因编码的一部分，该编码指定了前脑、头部外周结构和鳍中的模式形成或细胞命运决定。
