The Fox genes are united by encoding a fork head domain, a deoxyribonucleic acid (DNA)-binding domain of the winged-helix type that marks these genes as encoding transcription factors. Vertebrate Fox genes are classified into 23 subclasses named from FoxA to FoxS. We have surveyed the genome of the amphioxus Branchiostoma floridae, identifying 32 distinct Fox genes representing 21 of these 23 subclasses. The missing subclasses, FoxR and FoxS, are specific to vertebrates, and in addition, B. floridae has one further group, FoxAB, that is not found in vertebrates. Hence, we conclude B. floridae has maintained a high level of Fox gene diversity. Expressed sequence tag and complementary DNA sequence data support the expression of 23 genes. Several linkages between B. floridae Fox genes were noted, including some that have evolved relatively recently via tandem duplication in the amphioxus lineage and others that are more ancient.

中文翻译：

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佛罗里达分支口虫的 Fox 基因。

Fox 基因通过编码叉头结构域而结合在一起，这是一个有翼螺旋型的脱氧核糖核酸 (DNA) 结合结构域，将这些基因标记为编码转录因子。脊椎动物 Fox 基因分为 23 个亚类，从 FoxA 到 FoxS。我们调查了 amphioxus Branchiostoma floridae 的基因组，确定了代表这 23 个亚类中的 21 个的 32 个不同的 Fox 基因。缺失的亚类 FoxR 和 FoxS 是脊椎动物特有的，此外，B. floridae 还有一个在脊椎动物中未发现的组 FoxAB。因此，我们得出结论 B. floridae 保持了高水平的 Fox 基因多样性。表达的序列标签和互补 DNA 序列数据支持 23 个基因的表达。注意到 B. floridae Fox 基因之间的几个联系，