海洋硬骨鱼摄取大量含有各种离子的海水,包括0.4mM硼酸,它可以在体内积累到有毒水平。然而,海洋硬骨鱼吸收和排泄硼酸的分子机制尚不清楚。水通道蛋白(Aqps)与植物硼酸通道的结节蛋白样内在蛋白(NIP)家族同源。为了研究Aqps对海洋硬骨鱼中硼酸跨质膜运输的潜在作用,我们分析了日本河豚(Takifugurubbripes)在非洲爪狼卵母细胞中表达的Aqps的功能。Takifugu基因组数据库包含16个编码水通道蛋白家族成员(aqp0a,aqp0b,aqp1aa,aqp1ab,aqp3a,aqp4a,aqp7,aqp8bb,aqp9a,aqp9b,aqp10aa,aqp10bb,aqp11a,aqp11b,aqp12和aqp14)。当T.rubbripesAqps(TrAqps)在X.laevis卵母细胞中表达时,肿胀实验表明,在表达TrAqp3a的卵母细胞中,硼酸通透性显着增加,7,8bb,9a,9b。硼酸流入这些卵母细胞也通过元素定量得到证实。使用pH微电极的电生理学分析显示,这些TrAqp增加B(OH)3渗透性。这些结果表明,TrAqp3a,7,8bb,9a,和9b充当硼酸运输系统,可能作为频道,在海洋硬骨鱼中。
Marine teleosts ingest large amounts of seawater containing various ions, including 0.4 mM boric acid, which can accumulate at toxic levels in the body. However, the molecular mechanisms by which marine teleosts absorb and excrete boric acid are not well understood. Aquaporins (Aqps) are homologous to the nodulin-like intrinsic protein (NIP) family of plant boric acid channels. To investigate the potential roles of Aqps on boric acid transport across the plasma membrane in marine teleosts, we analyzed the function of Aqps of Japanese pufferfish (Takifugu rubripes) expressed in Xenopus laevis oocytes. Takifugu genome database contains 16 genes encoding the aquaporin family members (aqp0a, aqp0b, aqp1aa, aqp1ab, aqp3a, aqp4a, aqp7, aqp8bb, aqp9a, aqp9b, aqp10aa, aqp10bb, aqp11a, aqp11b, aqp12, and aqp14). When T. rubripes Aqps (TrAqps) were expressed in X. laevis oocytes, a swelling assay showed that boric acid permeability was significantly increased in oocytes expressing TrAqp3a, 7, 8bb, 9a, and 9b. The influx of boric acid into these oocytes was also confirmed by elemental quantification. Electrophysiological analysis using a pH microelectrode showed that these TrAqps increase B(OH)3 permeability. These results indicate that TrAqp3a, 7, 8bb, 9a, and 9b act as boric acid transport systems, likely as channels, in marine teleosts.