文昌鱼内胚层发育相关核心调控基因的表达
Expression of endodermal kernel regulatory genes during embryonic patterning in amphioxus

研究了脊椎动物内胚层发育的核心调控基因Sox2,Pdx1和Cdx1在文昌鱼胚胎发育过程中的表达形式.结果显示:与脊椎动物相比,Sox2基因在文昌鱼前肠内胚层的表达区域具有较大的阴性范围,这一阴性区域与文昌鱼的鳃弓原基相对应,说明原索动物的内胚层衍生鳃弓与脊椎动物的神经脊鳃弓在演化上并不具备器官层次的同源性;文昌鱼Pdx1基因阳性的前-中肠消化内胚层的表达状态与脊椎动物高度同源,对应于盲囊的内胚层发育原基,说明文昌鱼盲囊与脊椎动物的胰腺具有演化同源关系;Cdx1基因的表达状态也与脊椎动物高度同源,说明脊椎动物的复杂肠道系统是从较为简单的后肠器官演化而来的.
The expressions of three kernel vertebrate-endodermal regulatory genes, such as Sox2, Pdx1 and Cdx1, during amphioxus embryonic patterning are investigated. The results show that compared with vertebrates, the expressing region of Sox2 in amphioxus fore-gut endoderm has a large negative zone which corresponds to the primordium of gill slits, suggesting that the endoderm-derived gill slits in protochordates and the neural-crest-cell-derived pharyngeal gill slits in vertebrates are not evolutionary homologous physiological structures in the organ level. The expressions of Pdx1 in positive fore-mid-gut digestive endoderm of amphioxus, corresponding to the endodermal primordium of diverticulum, are highly homologous with those of the vertebrates, which indicates that the diverticulum in amphioxus is the homologous organ of pancreas. The expressions of Cdx1 of amphioxus are also highly homologous with those of the vertebrates, which reveals that the complicated intestine of the vertebrates is evolved from a simple primitive pioneer