Expansion of the Actin Gene Family in Amphioxus

文昌鱼肌动蛋白基因家族的扩增(英文)

Actins are a small family of ubiquitous proteins that are essential cytoskeletal components and are highly conserved during evolution. Actins are usually divided into two classes, the cytoplasmic and muscle actins, which have different functional roles. Here we systematically analyzed the actin genes in the genome of the primitive chordate amphioxus （Branchiostoma floridae）. We found that amphioxus contains more than 30 actin genes, many of which are linked. Phylogenetic analysis suggests the amphioxus actin genes have clearly undergone extensive expansion through tandem duplications. The actin genes＇ structure also varies a lot, containing 2 to 7 exons. We also cloned two muscle type of actin genes from the amphioxus （B. belcheri） and compared their expression patterns during early development. The slight difference in their expression suggests functional diversification of these actin genes. Our results shed light on the evolution both of actin genes themselves and their functional roles in chordate development.

肌动蛋白是一种分布广泛而且在进化上十分保守的蛋白,是构成细胞骨架的关键组分。肌动蛋白通常被分成肌肉型和胞质型两种类型,各自行使着不同的功能。在此,作者对弗罗里达文昌鱼基因组中的肌动蛋白基因家族进行了系统分析,发现文昌鱼中该基因家族成员多达30多个,其中很多都是连锁分布的。基因结构趋于多样,分别包含2-7个外显子。进化分析的结果显示,文昌鱼的肌动蛋白基因家族可能通过串联重复而发生了扩增。作者还克隆了厦门文昌鱼两个不同的肌肉型肌动蛋白基因,并比较了它们在文昌鱼早期胚胎中的表达图式。结果显示,这两个基因在表达上有着细微的差别,提示文昌鱼肌动蛋白基因家族成员在功能上的分化。上述结果将有助于阐明肌动蛋白基因家族及其功能在脊索动物中的演化。