Liu Gang, Huan Pin, Liu Baozhong
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, 266071, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Dev Genes Evol. 2017 Jun;227(3):181-188. doi: 10.1007/s00427-017-0579-2. Epub 2017 Mar 9.
Among the potential larval shell formation genes in mollusks, most are expressed in cells surrounding the shell field during the early phase of shell formation. The only exception (cgi-tyr1) is expressed in the whole larval mantle and thus represents a novel type of expression pattern. This study reports another gene with such an expression pattern. The gene encoded a SoxC homolog of the Pacific oyster Crassostrea gigas and was named cgi-soxc. Whole-mount in situ hybridization revealed that the gene was highly expressed in the whole larval mantle of early larvae. Based on its spatiotemporal expression, cgi-soxc is hypothesized to be involved in periostracum biogenesis, biomineralization, and regulation of cell proliferation. Furthermore, we investigated the interrelationship between cgi-soxc expression and two additional potential shell formation genes, cgi-tyr1 and cgi-gata2/3. The results confirmed co-expression of the three genes in the larval mantle of early D-veliger. Nevertheless, cgi-gata2/3 was only expressed in the mantle edge, and the other two genes were expressed in all mantle cells. Based on the spatial expression patterns of the three genes, two cell groups were identified from the larval mantle (tyr1 /soxc /gata2/3 cells and tyr1 /soxc /gata2/3 cells) and are important to study the differentiation and function of this tissue. The results of this study enrich our knowledge on the structure and function of larval mantle and provide important information to understand the molecular mechanisms of larval shell formation.
在软体动物潜在的幼虫贝壳形成基因中，大多数在贝壳形成早期阶段在围绕贝壳场的细胞中表达。唯一的例外（cgi-tyr1）在整个幼虫外套膜中表达，因此代表了一种新型的表达模式。本研究报道了另一个具有这种表达模式的基因。该基因编码太平洋牡蛎Crassostrea gigas的一个SoxC同源物，被命名为cgi-soxc。整体原位杂交显示该基因在早期幼虫的整个幼虫外套膜中高度表达。基于其时空表达，推测cgi-soxc参与壳皮生物发生、生物矿化和细胞增殖调控。此外，我们研究了cgi-soxc表达与另外两个潜在的贝壳形成基因cgi-tyr1和cgi-gata2/3之间的相互关系。结果证实这三个基因在早期D形幼虫的幼虫外套膜中共表达。然而，cgi-gata2/3仅在外套膜边缘表达，另外两个基因在所有外套膜细胞中表达。基于这三个基因的空间表达模式，从幼虫外套膜中鉴定出两个细胞群（tyr1 /soxc /gata2/3细胞和tyr1 /soxc /gata2/3细胞），它们对于研究该组织的分化和功能很重要。本研究结果丰富了我们对幼虫外套膜结构和功能的认识，并为理解幼虫贝壳形成的分子机制提供了重要信息。
