Ettensohn Charles A
Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA, 15213, USA.
Evol Dev. 2014 May;16(3):139-48. doi: 10.1111/ede.12074. Epub 2014 Apr 15.
It is widely accepted that biomineralized structures appeared independently in many metazoan clades during the Cambrian. How this occurred, and whether it involved the parallel co-option of a common set of biochemical and developmental pathways (i.e., a shared biomineralization "toolkit"), are questions that remain unanswered. Here, I provide evidence that horizontal gene transfer supported the evolution of biomineralization in some metazoans. I show that Msp130 proteins, first described as proteins expressed selectively by the biomineral-forming primary mesenchyme cells of the sea urchin embryo, have a much wider taxonomic distribution than was previously appreciated. Msp130 proteins are present in several invertebrate deuterostomes and in one protostome clade (molluscs). Surprisingly, closely related proteins are also present in many bacteria and several algae, and I propose that msp130 genes were introduced into metazoan lineages via multiple, independent horizontal gene transfer events. Phylogenetic analysis shows that the introduction of an ancestral msp130 gene occurred in the sea urchin lineage more than 250 million years ago and that msp130 genes underwent independent, parallel duplications in each of the metazoan phyla in which these genes are found.
人们普遍认为，生物矿化结构在寒武纪期间于许多后生动物类群中独立出现。这种情况是如何发生的，以及它是否涉及一套共同的生化和发育途径（即共享的生物矿化“工具包”）的平行共同选择，这些问题仍然没有答案。在这里，我提供证据表明水平基因转移支持了一些后生动物生物矿化的进化。我表明，Msp130蛋白最初被描述为海胆胚胎中形成生物矿的初级间充质细胞选择性表达的蛋白，其分类学分布比以前认为的要广泛得多。Msp130蛋白存在于几种无脊椎动物后口动物和一个原口动物类群（软体动物）中。令人惊讶的是，许多细菌和几种藻类中也存在密切相关的蛋白，我提出msp130基因是通过多次独立的水平基因转移事件引入后生动物谱系的。系统发育分析表明，一个祖先msp130基因的引入发生在2.5亿多年前海胆谱系中，并且msp130基因在发现这些基因的每个后生动物门中都经历了独立的、平行的复制。
