Identification of the changes of immune response, morphology, and gene expressions in hepatopancreas of Macrobrachium nipponense under the treatment of alkalinity exposure

Abstract

Macrobrachium nipponense exhibits limited alkali tolerance, restricting its cultivation in the predominant saline-alkaline water resources of China. Understanding the molecular and physiological mechanisms underlying alkaline acclimation is critical for enhancing its environmental adaptability through genetic improvement. This study comprehensively examines the hepatopancreatic responses of M. nipponense to alkaline stress (10 mmol/L) through integrated analyses of antioxidant enzyme activities, histological alterations, and transcriptomic profiling analysis. Results demonstrate that alkali stress significantly elevates the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), and Na+/K + -ATPase, suggesting their crucial role in mitigating oxidative damage, caused by the alkaline exposure. Histopathological analysis reveals structural alterations in the hepatopancreas after 96 h of exposure, particularly in luminal integrity, vacuolization, and storage cell morphology. Transcriptomic profiling analysis indicates minimal differential gene expression at this alkalinity; however, KEGG analysis identifies key enriched metabolic pathways, including fatty acid biosynthesis, fatty acid metabolism, insulin signalling pathway, and AMPK signalling pathway, as central to the adaptive response. These pathways are closely associated with energy metabolism, implying their regulatory significance in alkali acclimation. Quantitative real-time PCR validation confirms the transcriptomic data, ensuring methodological reliability. This study provides novel insights into the physiological and molecular adaptations of M. nipponense under alkaline stress, offering a foundation for future functional studies and marker-assisted breeding. Further research will focus on characterizing candidate genes and identifying associated single nucleotide polymorphisms (SNPs) to advance genetic enhancement in this species.