Vesicomyid clams, which inhabit deep-sea hydrothermal vents and hydrocarbon seeps, are nutritionally dependent on symbiotic, chemoautotrophic bacteria that produce organic matter by using hydrogen sulfide. Vesicomyid clams absorb hydrogen sulfide from the foot and transport it in their hemolymph to symbionts in the gill. However, mechanisms to cope with hydrogen sulfide toxicity are not fully understood. Previous studies on vent-specific invertebrates, including bathymodiolin mussels, suggest that hypotaurine, a precursor of taurine, mitigates hydrogen sulfide toxicity by binding it to bisulfide ion, so as to synthesize thiotaurine. In this study, we cloned cDNAs from the vesicomyid clam Phreagena okutanii for the taurine transporter that transports hypotaurine into cells and for cysteine dioxygenase and cysteine-sulfinate decarboxylase, major enzymes involved in hypotaurine synthesis. Results of reverse-transcription polymerase chain reaction indicate that mRNAs of these three genes are most abundant in the foot, followed by the gill. However, hypotaurine and thiotaurine levels, measured by reverse-phase high-performance liquid chromatography, were low in the foot and high in the gill. In addition, thiotaurine was detected in hemolymph cells. Hypotaurine synthesized in the foot may be transported to the gill after binding to bisulfide ion, possibly by hemolymph cells.

中文翻译：

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下丘脑和硫牛磺酸在类脉管蛤Phreagena okutanii中的可能作用

居住在深海热液喷口和碳氢化合物渗漏中的脉管蛤在营养上依赖于共生的化学自养细菌，这些细菌通过使用硫化氢产生有机物。囊壁蛤从脚吸收硫化氢，并在其血淋巴中将其运输到to中的共生体。但是，应对硫化氢毒性的机理尚不完全清楚。先前对通风孔特定的无脊椎动物，包括红水ym贻贝贻贝的研究表明，牛磺酸的前体次牛磺酸可通过与二硫键结合而减轻硫化氢的毒性，从而合成硫代牛磺酸。在这项研究中，我们从水囊蛤蛤Phreagena okutanii中克隆了cDNA。用于将牛磺酸转运到细胞中的牛磺酸转运蛋白，对于半胱氨酸双加氧酶和半胱氨酸亚磺酸脱羧酶，是参与牛磺酸合成的主要酶。逆转录聚合酶链反应的结果表明，这三个基因的mRNA在足部最丰富，其次是the。然而，通过反相高效液相色谱法测得的次牛磺酸和硫代牛磺酸水平在足部较低，and部较高。另外，在血淋巴细胞中检测到硫代牛磺酸。足中合成的亚尿素可能在结合到二硫化物离子后，可能被血淋巴细胞转运到the。