Test Morphogenesis in a Giant Antarctic Foraminiferan

巨大的有孔虫原生动物Astrammina rara受到矿物颗粒外壳(测试)的保护，矿物颗粒由耐化学物质、生物水泥或细胞外基质紧密结合在一起。粗略的观察表明，A.rara的分支和网状伪足网络从沉积物中收集更大的颗粒，分泌测试基质，并通过其协调活动来塑造测试。南极采集点的大型、易操作和高丰度的A.rara使这种生物特别适合于研究测试结构的特定方面。因为A.rara是一个巨大的单细胞系统，所以可以研究有关冷适应生物体中细胞外基质成分组装的一般问题，而不会出现后生动物系统常见的并发症。在测试构建过程中涉及的某些基本细胞过程的适应特别令人感兴趣，因为这些过程受到来自温带气候的生物体细胞中零度以下温度的抑制。各种生物技术方法将被用来在细胞和分子分析水平上获得关于测试结构的信息。拟议研究的完成不仅将有助于解决一个有趣的和长期存在的生物学问题，而且还将为未来对这一重要原生生物分类群的生理和进化的分子研究提供一个框架。

The giant foraminiferan protist, Astrammina rara, is protected by an outer shell (test) of mineral grains tightly bound by a chemically-resistant, biological cement or extracellular matrix. Cursory observations indicate that A. rara's network of branching and anastomosing pseudopodia collects larger particulates from the sediment, secretes the test matrix, and through its coordinated activity, sculpts the test. The large size, ease of handling, and high abundance of A. rara at the Antarctic collection site makes this organism uniquely suited for studying specific aspects of test construction. Because A. rara is a giant single-cell system, general questions regarding the assembly of extracellular matrix components in a cold-adapted organism can be studied without the complications common to metazoan systems. Adaptations in certain basic cellular processes involved in test construction are of particular interest because these processes are inhibited by subzero temperatures in the cells of organisms from temperate climates. Various biotechnological methods will be used to gain information on test construction at the cellular and molecular levels of analysis. Completion of the proposed studies will not only help solve an interesting and longstanding biological question, but will also provide a framework for future molecular studies of the physiology and evolution of this important protistan taxon.