形成原肠胚

In this paper, we studied M. meretrix ferritin, cathepsin B and caspase genes, which are involved in clam larval shell formation, nutrition, metabolism and apoptosis, respectively. We have cloned the three genes, investigated the temporal and spatial expression profile both at gene and protein level in trochophore (L1), D-veliger (L2), pediveliger (L3) and postlarvae (L4). The potential roles of these proteins were analyzed with specific inhibitors during larval development. Firstly, embryos were found developed into trochophore-like larvae with no shell if cultured at gastrula stage in artificial seawater without iron. Shell-like structures were formed only in the presence of iron. The larvae which had been transferred at L1 stage into ASW developed normal shell. This indicated that iron and iron associated protein are important for larval shell formation. The EST sequence which is homologous with ferritin, which is a principal iron metabolic protein, was selected from the M. meretrix cDNA library. The full-length of ferritin subunit cDNA was cloned by RACE. The results of real-time PCR revealed that the MmeFer mRNA expression changed before and after the larval shell formation.

本论文以文蛤幼虫为研究对象，分别对文蛤幼虫发育过程中贝壳形成相关的铁蛋白、营养及变态相关的组织蛋白酶B及变态过程中细胞凋亡相关的caspase三个基因进行了克隆，分析了基因及编码蛋白在担轮幼虫期(L1)、D形幼虫期(L2)、壳顶幼虫期(L3)和稚贝期(L4)的时空表达特征，解析了其可能的功能，并研究了相应酶类的特异性抑制剂作用对幼虫发育过程的影响，进行了目标蛋白的功能验证，详述如下：研究结果显示，在文蛤胚胎发育到原肠胚时放入不含铁离子的人工海水中培养，发育成无壳的畸形，随着人工海水中铁离子添加浓度的升高，幼虫长出壳状组织接近正常状态；而发育到L1期幼虫放入不含铁离子的人工海水中培养却可以发育出正常的壳，推测铁和铁代谢相关蛋白在幼虫贝壳初始形成有重要的作用。

We propose that the noncell-autonomous effects of Spemann's organizer on dorsoventral patterning are executed in part by diffusible signals that directly bind to and neutralize ventral BMPs during gastrulation.

我们提出，施佩曼组织器对背腹式的非细胞自发功能，有部分是通过原肠胚形成过程中，直接结合和抵消腹部BMP的扩散性信号所发挥的。

This is a process known as 'gastrulation'.

这一过程称为&原肠胚形成&。

This pushing-in of cells marks the start of gastrulation.

细胞的这种向里推进标志着原肠胚形成的开始。

Up to the stage called gastrulation, the cell aggregate may be divided artificially in two, and each remaining half will develop into a well-shaped individual.

直到原肠胚形成的阶段，细胞集合体也许人工地被划分成二个，并且各剩下的一半将显现出完整形状的个体。

PubMed abstract: Chordin is an abundant protein secreted by Spemann organizer tissue during gastrulation.

PubMed摘要：Chordin是原肠胚形成中，施佩曼组织器结构分泌的一种丰富蛋白质。

" During the second week following fertilization, gastrulation (cell differentiation and migration ) results in the formation of three tissue types."

受精之后第二周，原肠胚形成后，胚胎分化为三个组织类型

This intercalation event differs from the convergent extension movements of the mesoderm described in fish and amphibians4, 5, 6, 7, 8: it occurs before gastrulation and within a tight columnar epithelium.

多光子时差显微镜分析显示了与在鱼类和两栖类中所描述的运动不同的运动，这对脊椎动物胚胎学研究及原肠胚形成的演化研究有重要意义。

Using chicken eggs and a state-of-the-art imaging device which can reveal how cells move in three dimensions, the researchers demonstrated a key difference in the way gastrulation occurs between higher vertebrate species and less evolutionarily advanced animals.

利用鸡卵和能反应细胞三维移动的最新成像设备，科学家证明了高等脊椎动物和低等动物之间原肠胚形成的差异。

This site provides image materials on fish development, including time-lapse recordings illustrate the morphogenesis of zebrafish embryos, from early cleavage to organ rudiment formation, fish epidermal cell movies, 3-D films of zebrafish gastrulation, and much more.

该网站提供有关鱼类发育的图像材料，包括阐明斑马鱼胚胎形态发生（从早期卵裂到器官初期形成）的时间间隔录象、鱼类表皮细胞影片、斑马鱼原肠胚形成的三维影片，等等。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。