# Molecular Characterization of Anion Exchanger 2 in Litopenaeus vannamei and Its Role in Nitrite Stress

## TL;DR

This study explores the AE2 gene in shrimp and its role in handling nitrite stress, revealing its importance in maintaining pH balance and reducing nitrite toxicity.

## Contribution

The study identifies AE2's role in nitrite regulation and its interaction with NKCC1 in shrimp, offering new insights into mitigating nitrite toxicity.

## Key findings

- AE2 gene in shrimp encodes 1293 amino acids with Band3 and HCO3− domains.
- AE2 silencing increased shrimp survival and reduced hemolymph nitrite levels.
- AE2 and NKCC1 jointly regulate nitrite entry through gill tissue.

## Abstract

Anion exchanger 2 (AE2) mediates the Cl−/HCO3− transmembrane exchange process and regulates intracellular pH homeostasis. In this study, the AE2 gene (GenBank: PQ073349) was cloned and characterized from Litopenaeus vannamei using the rapid amplification of cDNA ends (RACE) technique. Employing bioinformatics, real-time fluorescence quantitative PCR, and RNA interference, we explored the gene’s sequence characteristics, tissue distribution, and the effects of nitrite on shrimp survival, physiology, and tissue damage following gene silencing. The results showed that AE2 cDNA was 5134 bp in length, encoding 1293 amino acids, which includes both the Band3 and HCO3− structural domains. AE2 was expressed in all tissues, with the highest expression in muscle. After silencing AE2, shrimp survival increased and hemolymph nitrite levels decreased. Notably, the oxidative stress enzyme system was not severely affected, and gill tissue damage was reduced. In addition, the expression level of Na+/K+/2Cl− cotransporter 1 (NKCC1) was significantly reduced (p < 0.05). These findings suggest that AE2 and NKCC1 are jointly involved in regulating the physiological process of nitrite entry into the shrimp body through gill tissue. Overall, this study provides a crucial experimental foundation for addressing the toxicity concerns associated with nitrite.