Proteomic and in silico characterization of stress-responsive proteins in the prawn penaeus indsicus under sublethal...

Copper contamination is a major challenge in brackishwater aquaculture, yet the molecular timeline of sublethal metal stress in penaeid prawns remains poorly understood. To address this, we applied time-resolved differential proteomics and in silico analyses to identify copper-responsive proteins in post-larval Penaeus indicus. Larvae were exposed to 0.1641 mg L^-3 copper (1/5 LC₅₀) for 24 h, 48 h, 96 h, 10 days, 20 days, and 30 days. Two-dimensional gel electrophoresis and MALDI-TOF/TOF revealed thirteen proteins across forty-one differential spots. Physicochemical and secondary structure characteristics were predicted using ExPASy ProtParam and the Self-Optimized Prediction Method with Alignment (SOPMA). Expression dynamics indicated three temporal phases: (i) early oxidative stress regulators (24-48 h), including thioredoxin and nuclear autoantigenic sperm protein, which were small, hydrophilic (GRAVY ≈ - 0.28), and coil-rich; (ii) mid-phase proteins such as ferritin (48-96 h), with a high α-helical content (61%) and moderate instability index (37.3), supporting metal sequestration and antioxidant buffering; and (iii) late-phase proteins (20-30 days), including variant transformer-2 and ubiquitin-activating enzyme, associated with proteostasis and cellular remodeling. Together, these findings suggest a three-tier biomarker model: thioredoxin (early), ferritin (mid), and variant transformer-2 (late). This timeline-based framework may improve the precision of copper stress monitoring and supports future investigations integrating proteomic data with transcriptomic and functional validation in crustaceans.