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. In the previous reporting periods, the HVEM was used in a study to compare and contrast allogromia pseudopodia with reticulopodia of foraminferia, and to document the presence or absence of microtubules and other organelles characteristic of Foraminifera. HVEM stereo pairs were recorded to investigate foraminifera membrane invaginations associated with pore plugs. Two tomographic tilt series of a silver saccammina shell were recorded using the HVEM. Reconstructions were made, and a surface model was generated.
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