Physiochemical Study on Highly Selective Accumulation of Vanadium Ions by Ascidians

人们对海鞘中的钒有很多了解，海鞘也被称为被囊动物或海鞘。例如，在属细鳃亚目的海鞘（Ascidia gemmata）的血细胞中，钒的浓度达到350毫米，在大约10种血液中，钒的浓度是海水中的10 ^7倍。细胞，印戒细胞是真正的钒细胞，含钒的血细胞，几乎所有的钒都通过+4氧化态（V^<IV>）还原为+3氧化态（V^<III>）并储存在钒细胞的液泡中，尽管钒在海水中处于+5氧化态（V^V）。研究发现：从雪梨猕猴血细胞中提取的钒相关蛋白（VAP）每摩尔含有16个钒原子；在除海鞘外首次发现含钒高的动物——伪鱼多毛藻（Pseudopotamilla occelata）的沉淀蛋白中检测到与VAP多克隆抗体识别的相同抗原；apo-VAP， VAP除去钒，发现能结合10个钒原子；揭示了编码VAPs 12.5 kDa和15 kDa的cdna的核苷酸序列；用表达VAPs基因的质粒载体转染大肠杆菌，分离到一个融合蛋白；制备了钒细胞空泡膜特异性单克隆抗体；钒钠细胞胞质中存在戊糖磷酸途径中的G6PDH、6PGDH、转酮醇酶和糖原磷酸化酶；NADPH可将V^V-EDTA降至V^<IV>-EDTA。

A lot is known about the vanadium in ascidians, which are also known as tunicates or sea squirts. For example, the concentration of vanadium attains 350 mMin the blood cells of Ascidia gemmata belonging to the suborder Phlebobranchia, which is l0^7times higher than the concentration in sea water among approximately ten types of blood. cells, signet ring cells are true vanadocytes, vanadium-containing blood cells, almost all vanadium is reduced to the +3 oxidation state (V^<III>) via the +4 oxidation state (V^<IV>) and stored in vacuoles of vanadocytes, although vanadium is in the +5 oxidation state (V^V) in seawater.We have revealed by the research project followings : a vanadium-associated protein (VAP) extracted from the blood cells of A.sydneiensis sames 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 the first animal revealed to contain high levels of vanadium besides ascidians ; apo-VAP, VAP removed vanadium, was found to bind 10 atoms of vanadium ; the nucleotide sequences of cDNAs encoding 12.5 kDa and 15 kDa of VAPs are revealed ; a fusion protein was isolated from E.coil transfected with plasmid vector expressing VAPs genes ; a monoclonal antibody specific to vacuolar membrane of vanadocytes was prepared ; 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^V-EDTA to V^<IV>-EDTA.