Nitrite and sulfide stress affects physiological and metabolic functions of gills in crab Eriocheir sinensis

Abstract

Nitrite and sulfide are environmental factors that affect crabs survival and immunity. Gills are important respiratory and immune organs of Chinese mitten crabs Eriocheir sinensis, and both nitrite and sulfide can affect the physiological function stability of gill tissues. The present study investigated the acute toxicity of 10 mg/L nitrite and 5 mg/L sulfide, single and in combination, on the morphological, immune, osmoregulatory, and metabolic functions of the gill tissues of Chinese mitten crab. Both single and combined stressors were observed to disrupt the structural integrity of gill tissues. Oxidative stress-related indicators, including MDA, H2O2, and ·O2− content, exhibited an increase in all stress groups. The activities of antioxidant enzymes such as CAT and SOD and the expression levels of antioxidant genes fluctuated to varying degrees in all stress groups. The expression levels of osmotic regulating genes such as aqp, vatp, and nhe increased, as did the expression levels of lipid metabolism-related genes such as pparγ, rxr, fabp1, gyk, and dgat1. Furthermore, nitrite and sulfide stress affected the functions of metabolic pathways related to arachidonic acid, linoleic acid, D-amino acids, phenylalanine, and other substances in Chinese mitten crabs gill tissues. Additionally, the study identified 18 potential biomarkers related to stress responses. The nitrite and sulfide stressors disrupt the structure of crab gill tissues, cause osmoregulation disturbances, immune dysfunction, induce amino acid and lipid metabolic changes in gill tissue.