BIOADHESIVE SECRETION OF SECRETORY ORGANELLES IN FORAMINIFERA

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 摘要： 凝集有孔虫原生生物的测试(壳)由矿物颗粒组成，矿物颗粒被一种耐化学物质的生物粘合剂(即“细胞外基质”的“生物粘合剂”)紧密地结合在一起。在测试形态发生过程中，它们的伪足网络从沉积物中收集矿物颗粒，在适当的数量和位置分泌生物粘合剂，并通过它们的协调运动，雕刻出这些建筑优雅的结构。在我们的南极采集点，关键的巨型凝集物种的高度丰富使这个有孔虫群落特别适合于研究凝集测试构建的特定方面，并解决与该组的系统发育有关的相关问题。我们的形态发生研究将集中在Astrammina rara-一个巨大的单细胞系统，使我们能够研究冷适应海洋生物中生物黏附的分泌和组装，而不会出现后生动物系统常见的细胞-细胞和细胞-组织相互作用的并发症。使用延时视频显微镜、光镜和电子显微镜细胞化学和聚丙烯酰胺凝胶电泳法的研究将在细胞和生化分析水平上提供关于凝集试验构建的信息。材料测试和有限元分析将表征A.rara生物粘附剂的机械性能。从实用的角度来看，这种环境安全的生物粘附剂结合了免疫球蛋白，并具有可能具有生物技术应用的有用材料特性。最后，基于选定物种的18S rDNA序列数据的分子系统发育分析将为确定这一重要的蛋白质类群的进化提供一个亟需的框架。 在RVBC之前的工作中，整个数量的Astrammina rara被免疫标记为粘附蛋白。以前未知的深海有孔虫被发现有自养细菌，在有孔-共生复合体上有膜特化(错综复杂的质膜内陷)。在确定这些内陷的三维结构时，厚层切片的HVEM是必不可少的。[Bowser，S.S.，Bernhard，J.M.，Habura，A.和Gooday，A.J.(2002)三角阿斯特拉明斯(Astrammina triangularis(Earland))的结构、分类和生态学。J.有孔虫研究32：364-374。]与英国南安普顿大学南安普顿海洋中心的Ana da Silva博士合作，我们结合了分子和结构数据集来研究极地有孔虫是从深海物种进化而来，还是反之亦然。我们发现，从阿拉伯海采集的标本根本不是有孔虫，而是很少被研究的巨型遗嘱阿米巴的姐妹群。这些“格罗米亚”物种对它们在海平面以下1000米处经历的低氧条件表现出了迷人的适应能力。具体地说，我们发现细菌停靠在它们表面的特定点上--这些可能是帮助它们在缺氧中生存的化学自养生物。 。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: The tests (shells) of agglutinated foraminiferan protists are composed of mineral grains tightly bound by a chemically-resistant, biological cement (i.e., "bioadhesive" of "extracellular matrix"). During test morphogenesis, their pseudopodial networks collect mineral grains from the sediment, secrete bioadhesives in the proper amount and location, and through their coordinated movements, sculpt these architecturally-elegant structures. The high abundance of key, giant agglutinated species at our antarctic collection site makes this foraminiferan community uniquely suited for studying specific aspects of agglutinated test construction, and addressing related questions concerning the phylogeny of the group. Our morphogenetic studies will focus on Astrammina rara - a giant unicellular system that allows us to study the secretion and assembly of bioadhesive in a cold-adapted marine organism without the complications of cell-cell and cell-tissue interactions common to the metazoan systems. Studies using time-lapse videomicroscopy, light -and electron-microscopic cytochemistry and polyacrylamide gel electrophoresis will provide information on agglutinated test construction at the cellular and biochemical levels of analysis. Materials testing with finite element analysis will characterize the mechanical properties of A. rara's bioadhesive. From a practical standpoint, this environmentally-safe bioadhesive binds immunoglobulins and has useful material properties that may have biotechnological applications. Finally, molecular phylogenetic analyses, based on 18S rDNA sequence data of selected species, will provide a much-needed framework for determining the evolution of this important protisan taxon. In previous work at the RVBC, whole mounts of Astrammina rara were immunolabelled for adhesion proteins. Previously-unidentified foraminifera from the deep sea were found to have cemoautotrophic bacteria, with membrane specializations (intricate invaginations of the plasma membrane) at the foram-symbiont junctional complex. HVEM of thick sections was essential in determining the 3D structure of these invaginations. [Bowser, S.S., Bernhard, J.M., Habura, A., and Gooday, A.J. (2002) Structure, taxonomy and ecology of Astrammina triangularis (Earland), an allogromid-like agglutinated foraminifer from explorers cove, Antartica. J. Foraminiferal Res. 32: 364-374.] In collaboration with Dr. Ana da Silva of the Southampton Oceanographic Centre, University of Southampton, UK, we combined molecular and structural datasets to investigate whether the polar foraminifera evolved from deep-sea species, or vice-versa. We found that the specimens collected from the Arabian Sea were not foraminifera at all, but rather a rarely-studied sister group of giant testate amoebae. These "Gromia" species showed fascinating adaptations to the low oxygen conditions they experienced 1000 meters below sea level. Specifically, we found bacteria docked at specific points along their surfaces -- these were probably chemoautotrophs that help them survive hypoxia. .