The air-breathing magur catfish (Clarias magur) is a potential ureogenic teleost because of its functional ornithine-urea cycle (OUC), unlike typical freshwater teleosts. The ability to convert ammonia waste to urea was a significant step towards land-based life forms from aquatic predecessors. Here we investigated the molecular characterization of some OUC genes and the molecular basis of stimulation of ureogenesis via the OUC in magur catfish. The deduced amino acid sequences from the complete cDNA coding sequences of ornithine transcarbamyolase, argininosuccinate synthase, and argininosuccinate lyase indicated that phylogenetically magur catfish is very close to other ureogenic catfishes. Ammonia exposure led to a significant induction of major OUC genes and the gene products in hepatic and in certain non-hepatic tissues of magur catfish. Hence, it is reasonable to assume that the induction of ureogenesis in magur catfish under hyper-ammonia stress is mediated through the activation of OUC genes as an adaptational strategy.

呼吸马库尔cat鱼（Clarias magur）是鸟尿素-尿素周期（OUC）的功能，是一种潜在的尿素硬骨鱼，与典型的淡水硬骨鱼不同。将氨废物转化为尿素的能力是向水生生物迈向陆基生命形式的重要一步。在这里，我们研究了一些O鱼基因的分子特征以及通过mag鱼刺激尿ure鱼尿毒症的分子基础。从鸟氨酸转氨甲酚酶，精氨琥珀酸合酶和精氨琥珀酸裂合酶的完整cDNA编码序列推导的氨基酸序列表明，系统发育上的magur fish鱼与其他脲原性cat鱼非常接近。氨暴露导致巨鱼肝和某些非肝组织中的主要OUC基因和基因产物得到显着诱导。因此，