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. Biological systems employ metals in diverse processes. Titanium is environmentally very abundant but not usually bioavailable, and its role in biology is unappreciated. Some species, however, sequester remarkably high concentrations of titanium from their surroundings, by unknown mechanisms and for unknown purpose. The most striking is Eudistoma ritteri, a common ascidian (sea squirt) native to the central California coast. The marine invertebrate sequesters Ti at as much as a ten million- fold concentration increase over its ocean environment. Colonies of Eudisotma ritteri were collected at the Hopkins Marine Station of Stanford University and at the Bodega Bay marine station of the University of California, Davis. Their titanium content was confirmed by atomic absorption spectroscopy, which is a destructive technique affording no information about metal environment. By using X-ray absorption spectroscopies, the titanium environment will be interrogated in minimally processed colonies to determine the distribution, oxidation state and chemical environment of the titanium. Since Ti is localized at high concentration within the tissues, the microprobe is ideally suited to local investigation of the Ti chemistry. The XRF capabilites of the microprobe will also show correlations with other elements in the tissues. Characterization of the Ti environment will help elucidate how this organism acquires such an astonishing quantity of the hydrolysis-prone metal and will direct inquiries as to its function. The elaboration of a role for titanium in bioinorganic chemistry will have tremendous impacts narrowly on that hybrid field, on its antecedent fields biological and inorganic chemistry, as well as more broadly on environmental chemistry including origin of life issues.
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