Transcriptomic analysis of gills in nitrite-tolerant and -sensitive families of Litopenaeus vannamei.

Abstract Nitrite stress is a major environmental factor that limits aquatic animal growth, reproduction and survival. Even so, some shrimp can withstand somewhat high concentrations of nitrite environment as our previous studies indicated. Therefore, we hypothesized that these shrimps might have specific adaptive strategies to adapt to high concentrations of nitrite environment. To identify the genes and pathways involved in the regulation of nitrite tolerance, we performed comparative transcriptomic analysis in the Litopenaeus vannamei nitrite-tolerant (NT) and nitrite-sensitive (NS) families, and untreated shrimps were used as the control group. After 24 h of nitrite exposure (NaNO2, 112.5 mg/L), a total of 1521 and 868 differentially expressed genes (DEGs) were obtained from NT compared with NS and control group, respectively. Functional enrichment analysis revealed that most of these DEGs were involved in immune defense, energy metabolism processes and endoplasmic reticulum (ER) stress. Nitrite stress significantly enhanced energy metabolism in NT by activating the expression of genes encoding key enzymes in oxidative phosphorylation (OXPHOS) pathway and tricarboxylic acid (TCA) cycle. Furthermore, some DEGs involved in innate immunity- related genes and pathways, and ER stress responses were highly expressed in NT. Therefore, we speculate that accelerated energy metabolism, higher expression of immunity and ER related genes might be the important adaptive strategies for NT in relative to NS under nitrite stress. These results will provide new sights on the potential tolerant molecular mechanisms and the breeding of new varieties of nitrite tolerant L. vannamei, with possible implications for other aquatic animals.