Transcriptomic Analysis of Litopenaeus vannamei: Understanding Salinity Adaptation Mechanisms in Freshwater Environments.

Litopenaeus vannamei exhibits strong salinity adaptation; however, its survival and growth are significantly reduced in freshwater environments. To investigate the response mechanisms of L. vannamei to freshwater conditions, gill tissues from shrimp cultured for 30 days in both freshwater and seawater environments were used as experimental material in this study. Transcriptome sequencing was performed using the Illumina platform to analyze differentially expressed genes (DEGs) and regulatory pathways associated with salinity stress. Additionally, real-time quantitative PCR was employed to validate the transcriptome findings. A total of 1173 DEGs were identified between the groups, including 408 upregulated and 765 downregulated genes. These DEGs were primarily associated with pathways related to ATP binding, metabolic processes, oxidative phosphorylation, purine metabolism, and phagosome formation. Litopenaeus vannamei appears to adopt to salinity stress by enhancing energy metabolism pathways such as oxidative phosphorylation to meet the increased energy demands of osmoregulation. The upregulation of the glutathione metabolism pathway likely contributes to mitigating oxidative damage induced by salinity stress. Furthermore, the enrichment of genes in the structural constituent of cuticle pathway suggests a role in ion regulation and maintenance of osmotic balance. This study provides foundational data for advancing the understanding of physiological response mechanisms in L. vannamei under freshwater aquaculture conditions.