In this study, we reported a novel member of Forkhead box (Fox) proteins found in model zebrafish (Danio rerio). This new gene we cloned was primarily assigned as zgc:162612, which locates on Chromosome 3 at 26,108,033–26,109,322 in the zebrafish genome, but encodes an uncharacterized protein, LOC100037333. After we determined the nucleotide and deduced amino acid sequences of zgc:162612, we found that zgc:162612 is an intronless gene and contains 1290 base pairs encoding 308 amino acid residues. Zgc:162612 protein is composed of a highly conserved DNA-binding domain similar to that of the Fox protein family, but with variable terminal domains. Based on phylogenetic analysis of all known members within the zebrafish Fox protein family, zgc:162612 was clustered into the zebrafish FoxD isoform subfamily. Thus, we confirmed zgc:162612 as the zebrafish FoxD7 gene. The deduced amino acid sequence of zebrafish FoxD7 shared 49, 49, 74, 63 and 74% identities with that of zebrafish FoxD1, FoxD2, FoxD3, FoxD4 and FoxD6, respectively. Compared with all known FoxD proteins in invertebrate and vertebrate species, the zebrafish FoxD7 is categorized in the same monophyletic group along with FoxD of cephalochordate and sea urchin. Whole-mount in situ hybridization demonstrated that zebrafish FoxD7 transcripts represented maternal inheritance and were ubiquitously expressed throughout the whole embryo at 12hpf. Moreover, while FoxD7 transcripts were expressed in the brain, spinal cord, fins and eyes at early developmental stages, they were mainly presented in the telencephalon ventricular zone at late developmental stages, suggesting that FoxD7 may play roles in neurogenesis and organogenesis during development of zebrafish. Taken together, we have defined a previously uncharacterized gene in the zebrafish genome, zgc:162612, and revealed that Zgc:162612 encodes a novel putative transcription factor, thus becoming a new member of the zebrafish FoxD isoform subfamily.

在这项研究中，我们报道了在模型斑马鱼（Danio rerio）中发现的Forkhead box（Fox）蛋白的新成员。我们克隆的这个新基因主要被命名为z gc：162612，它位于斑马鱼基因组中的3号染色体上26,108,033–26,109,322，但编码一个未表征的蛋白质LOC100037333。在确定zgc：162612的核苷酸和推导的氨基酸序列后，我们发现zgc：162612是无内含子基因，包含1290个碱基对，编码308个氨基酸残基。Zgc：162612蛋白由与Fox蛋白家族相似的高度保守的DNA结合结构域组成，但具有可变的末端结构域。基于对斑马鱼Fox蛋白家族中所有已知成员的系统发育分析，zgc：162612被聚类到了斑马鱼FoxD亚型中。因此，我们确认了zgc：162612为斑马鱼FoxD7基因。推测的斑马鱼FoxD7的氨基酸序列分别与斑马鱼FoxD1，FoxD2，FoxD3，FoxD4和FoxD6具有49、49、74、63和74％的同一性。与无脊椎动物和脊椎动物物种中所有已知的FoxD蛋白相比，斑马鱼FoxD7与头孢酸盐和海胆的FoxD归为同一单系。整个原位杂交表明，斑马鱼FoxD7转录本代表母体遗传，并以12hpf在整个胚胎中普遍表达。而且，虽然FoxD7转录本在发育的早期阶段在脑，脊髓，鳍和眼睛中表达，它们主要在发育后期的末梢脑室区域呈现，提示FoxD7可能在斑马鱼的发育过程中参与神经发生和器官发生。综上所述，我们已经在斑马鱼基因组中定义了一个先前未表征的基因z gc：162612，并揭示了Zgc：162612编码一种新型的假定转录因子，从而成为了斑马鱼FoxD亚型的新成员。