| Co-Investigator(Kenkyū-buntansha) |
UEKI Tatsuya Hiroshima University, Faculty of Science, Assistant, 理学部, 助手 (10274705)
KANAMORI Kan Toyama University, Faculty of Science, Professor, 理学部, 教授 (00019001)
MICHIBATA Hitoshi Hiroshima University, Faculty of Science, Professor, 理学部, 教授 (00111740)
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| Research Abstract |
Ascidians, known as tunicates or sea squirts (Chordata, Urochordata, Ascidiacea), accumulate extremely high levels of vanadium in vanadocytes, one of their approximately ten types of blood cell. The vanadium concentration in vanadocytes can reach 350 mM, corresponding to 10ィイD17ィエD1 times the level in seawater, where vanadium is dissolved at a concentration of 35 nM. This is thought to be the highest rate of concentration of a metal in any living organism.
We have revealed by the research project followings: a vanadium-associated protein (VAP) extracted from the blood cells of Ascidia sydneiensis samea was revealed to contain 16 atoms of vanadium per a mol; the same antigen recognized with a polyclonal antibody against VAP was detected in the precipitated proteins of the polychaete Pseudopotamilla occelata which was first animal revealed to contain high levels of vanadium besides ascidians; G6PDH, 6PGDH, and transketolase in the pentose phosphate pathway and glycogen phosphorylase were found to be in the cytoplasm of vanadocytes ; NADPH was revealed to reduce VィイD1VィエD1-EDTA to VIィイD1IVィエD1-EDTA ; ascidian Nramp homolog, named AsNramp2, have been isolated from cDNA library of blood cells of vanadium-rich ascidian, A. sydneiensis samea. The deduced amino acid sequence showed a striking similarity to the known Nramp2 from various organisms.
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