*Article* **A Na+/H+-Exchanger Gene from** *Penaeus monodon***: Molecular Characterization and Expression Analysis under Ammonia Nitrogen Stress**

**Yundong Li 1,2,3,4, Shigui Jiang 1,2, Hongdi Fan 1, Qibin Yang 1,2, Song Jiang 1, Jianhua Huang 1, Lishi Yang 1, Wenwen Zhang 1, Xu Chen <sup>2</sup> and Falin Zhou 1,2,3,\***


**Abstract:** Na+/H+-exchanger (NHE) assumes a significant part in different particle transport in creatures. A clone of *Penaeus monodon* NHE cDNA was examined in this study (*PmNHE*), and its impact on high-concentration ammonia nitrogen stress was researched. The 877-amino acid (aa) protein was encoded by a full-length *PmNHE* cDNA that was 2788 base pairs (bp) long and had a 2643-bp open reading frame (ORF). The findings show that *PmNHE* was expressed in all of the *P. monodon* organs that were tested, including the intestine, muscle, hemolymph, heart, hepatopancreas, stomach, epidermis, gill, testis, and ovary, and the intestine and muscle were found to have the highest levels of *PmNHE* expression. The expression of *PmNHE* in the gill tissue of *P. monodon* was significantly up-regulated under high levels of ammonia nitrogen stress. The expression of *PmNHE* in the intestine of *P. monodon* under high-concentration ammonia nitrogen stress was significant. When exposed to high concentrations of ammonia nitrogen stress, *P. monodon* exhibited shorter survival times than the two control groups. Hence, it is suggested in the present study that *PmNHE* may have a significant impact on the environment with high levels of ammonia nitrogen.

**Keywords:** NHE; Penaeus monodon; ammonia nitrogen stress; intestine; gill; RNAi
