Expression of a Hox gene, Cnox-2, and the division of labor in a colonial hydroid

We report the isolation and expression of the Hox gene, Cnox-2, in Hydractinia symbiolongicarpus, a hydrozoan displaying division of labor. We found different patterns of aboral-to-oral Cnox-2 expression among polyp polymorphs, and we show that experimental conversion of one polyp type to another is accompanied by concordant alteration in Cnox-2 expression. Our results are consistent with the suggestion that polyp polymorphism, characteristic of hydractiniid hydroids, arose via evolutionary modification of proportioning of head to body column.

本研究报道了共生玉螅（Hydractinia symbiolongicarpus）——一种具备劳动分工特征的水螅虫类动物——的同源框基因（Hox gene）Cnox-2的克隆与表达特征。我们发现，不同水螅体多态型中，Cnox-2的反口极至口极表达模式存在显著差异；同时实验证实，将一种水螅体类型经实验性转化为另一类型时，伴随有Cnox-2表达模式的一致性改变。本研究结果与下述假说相符：作为玉螅科水螅典型特征的水螅体多态性，是通过头部与躯干柱比例的进化修饰演化形成的。