中文摘要：

engrailed基因属于同源异形基因家族成员，在许多动物的分节、附肢发育、神经系统发育和贝壳形成过程中发挥作用。本研究克隆了长牡蛎两个engrailed同源基因，命名为cgi-engl和cgf-eng2。序列分析表明，两个基因均具备典型engrailed基因保守的5个EH结构域。利用整装原位杂交技术检测了cgi-engl和cgi-eng2在贝壳形成的关键时期早期D形幼虫时期的表达情况。结果显示，cgi-engl和cgi-eng2mRNA高表达于贝壳外缘，可能与早期贝壳形成过程有关。此外，两个基因的在贝壳外缘的表达模式亦有区别，提示两个基因的功能可能存在一定程度的分化。本研究首次系统鉴定了长牡蛎engrailed基因的成员，并发现它们可能均参与幼虫贝壳形成，研究结果有助于加深对贝类早期发育及贝壳形成的理解。

英文摘要：

engrailed, a homeodomain-containing gene, functions in segmentation, limb development, central nerv- ous system development and larval shell formation in many species. In the present study, we cloned two en- grailed-homologs in Crassostrea gigas and designated them as cgi-engl and cgi-eng2. The expression patterns of the two engrailed-homologs were investigated in early D-veligers, which represented one crucial stage of shell de- velopment, using whole mount in situ hybridization （WMISH）. The results showed that the two genes were highly expressed in the edge of shell field, indicating that cgi-eng! and cgi-eng2 might participate in larval shell formation. Moreover, different expression patterns of cgi-engl and cgi-eng2 indicated potential function differentiations of the two genes. This study firstly identified two engrailed-homolgs in C. gigas and predicted their potential roles in lar- val shell formation, which might shed new light on studies of early development of mollusks and molecular mecha- nisms of larval shell formation.