Regulation of Vascular Development in Hydrozoa

血管系统对于大多数体型较大的动物的生长和发育至关重要 因为扩散不充分。刺胞动物的成员，最早的动物之一 门，表现出原始的维管系统。群体刺胞动物由珊瑚虫组成，通过 一个共同的血管系统整合了整个群体的行为。珊瑚虫通过以下方式收集和分配食物 通过胃血管系统泵入。血管运输对食物供应、氧气 张力和其他环境因素以及血管结构。殖民地的形成与 胃血管运输和因此菌落形式的可塑性是相当大的，并且可以是适应性的。 该项目的目标是确定调节血管发育的机制及其 水螅动物的可塑性代表了后生动物共有的原始特征。为实现这一目标， 测试以下假设：（1）水螅虫菌落形式响应氧张力（pO 2）是可塑的， 和操纵海水粘度，改变对匍匐茎的内胚层细胞的剪切应力。(2)率 不同长度的匍匐茎内胚层细胞的息肉形成、匍匐茎分枝和有丝分裂不同， 它们所栖息的匍匐茎的结构。(3)内胚层细胞的有丝分裂率 匍匐茎对低氧和维管切应力的响应增加。(4)HIF-1 α，VEGF， 和基质金属蛋白酶基因同源物在缺氧和血管切应力反应中增加 并且因此与调节匍匐茎的生长和分枝的作用一致。如果血管发育 水螅动物和脊椎动物的生长受到相同机制的调节，长期目标是发展 集群水螅虫作为脊椎动物的替代和补充模型，用于血管的研究 功能及其病理。 事实上，这项研究与公共卫生的相关性在于水螅虫胃血管疾病的可能性。 系统作为人类血管功能研究的模型，因为进化保守， 由生理反应触发的发育信号通路。利用的实际好处 它们作为模型包括体内实验、低成本、克隆复制和很少的伦理约束。

Vascular systems are essential for the growth and development of most animals larger than a few centimeters in size because diffusion is inadequate. Members of the Cnidaria, one of the earliest animal phyla, exhibit primitive vascular systems. Colonial cnidarians consist of polyps connected to one another by a common vascular system that integrates colony-wide behavior. Polyps gather and distribute food by pumping it through the gastrovascular system. Vascular transport is sensitive to food availability, oxygen tension and other environmental factors, and vascular architecture. Colony form is inextricably linked to gastrovascular transport and, consequently, plasticity of colony form is considerable and can be adaptive. The goal of the proposed project is to determine if mechanisms regulating vascular development and its plasticity in hydrozoans represent shared primitive characters of metazoans. This objective will be met by testing the following hypotheses: (1) Hydrozoan colony form is plastic in response to oxygen tension (pO2), and manipulations of seawater viscosity that alter shear stress on endodermal cells of stolons. (2) Rates of polyp formation, stolon branching and mitosis of stolon endodermal cells differ with the length and architecture of the stolon on which they reside. (3) Mitotic rates of endodermal cells lining the lumen of stolons increase in response to hypoxia and vascular shear stress. (4) Expression of HIF-1 alpha, VEGF, and matrix metalloproteinase gene homologues increase in response to hypoxia and vascular shear stress and are, therefore, consistent with roles regulating growth and branching of stolons. If vascular development of hydrozoans and vertebrates are regulated by the same mechanisms, the long-term goal is to develop colonial hydrozoans as alternative and complementary models to those of vertebrates for studies of vascular function and its pathologies. Indeed, the relevance of this research to public health lies in the potential for hydrozoan gastrovascular systems to serve as models for studies of human vascular function because of evolutionary conservation of developmental signaling pathways triggered by physiological responses. The practical benefits of utilizing them as models include in vivo experimentation, low cost, clonal replication, and few ethical constraints.