Uyama T, Moriyama Y, Futai M, Michibata H
Mukaishima Marine Biological Laboratory, Faculty of Science, Hiroshima University, Japan.
J Exp Zool. 1994 Oct 1;270(2):148-54. doi: 10.1002/jez.1402700204.
Ascidians belonging to the family Ascidiidae are known to accumulate vanadium from seawater in their blood cells, concentrating vanadium by a factor of 10(7). Among several different types of blood cell, the signet ring cells have both high levels of vanadium and a low pH. These observations suggest the possibility that proton ions concentrated by a H(+)-ATPase are energetically linked to the accumulation of vanadium. In the present experiments, therefore, we made an immunological search for a H(+)-ATPase in the vacuolar membranes of the signet ring cells, as a first step in our attempts to clarify the energetics of the accumulation of vanadium by these cells. Antibodies raised against the 72-kDa and 57-kDa subunits of a vacuolar-type H(+)-ATPase from bovine chromaffin granules reacted with the vacuolar membranes of signet ring cells. Immunoblotting analysis confirmed that specific antigens in ascidian blood cells actually reacted with the antibodies. Furthermore, addition of bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibited the uptake of protons by the vacuoles of signet ring cells. Thus, the addition of bafilomycin A1 inhibited the pumping function of the vacuoles of signet ring cells, with resultant neutralization of the contents of the vacuoles.
属于海鞘科的海鞘已知能在其血细胞中从海水中积累钒，将钒浓缩10的7次方倍。在几种不同类型的血细胞中，印戒细胞的钒含量高且pH值低。这些观察结果表明，由H(+)-ATP酶浓缩的质子离子在能量上可能与钒的积累有关。因此，在本实验中，作为我们试图阐明这些细胞积累钒的能量学的第一步，我们对印戒细胞液泡膜中的H(+)-ATP酶进行了免疫学搜索。针对牛嗜铬颗粒的液泡型H(+)-ATP酶的72-kDa和57-kDa亚基产生的抗体与印戒细胞的液泡膜发生反应。免疫印迹分析证实，海鞘血细胞中的特定抗原确实与抗体发生了反应。此外，添加液泡型H(+)-ATP酶的特异性抑制剂巴弗洛霉素A1可抑制印戒细胞液泡对质子的摄取。因此，添加巴弗洛霉素A1会抑制印戒细胞液泡的泵功能，从而使液泡内容物中和。
