Ammonia stress affects the structure and function of hemocyanin in Penaeus vannamei

Anthropogenic factors and climate change have serious effects on the aquatic ecosystem and aquaculture. Among water pollutants, ammonia has the greatest impact on aquaculture organisms such as penaeid shrimp because it makes them more susceptible to infections. In this study, we explored the effects of ammonia stress (0, 50, 100, and 150 mg/L) on the molecular structure and functions of the multifunctional respiratory protein hemocyanin (HMC) in Penaeus vannamei. While the mRNA expression of Penaeus vannamei hemocyanin (PvHMC) was up -regulated after ammonia stress, both plasma hemocyanin protein and oxyhemocyanin (OxyHMC) levels decreased. Moreover, ammonia stress changed the molecular structure of hemocyanin, modulated the expression of protein phosphatase 2 A (PP2A) and casein kinase 2 alpha (CK2 alpha) to regulate the phosphorylation modification of hemocyanin, and enhanced its degradation into fragments by trypsin. Under moderate ammonia stress condi-tions, hemocyanin also undergoes glycosylation to improve its in vitro antibacterial activity and binding with Gram-negative (Vibrio parahaemolyticus) and Gram-positive (Staphylococcus aureus) bacteria, albeit differently. The current findings indicate that P. vannamei hemocyanin undergoes adaptive molecular modifications under ammonia stress enabling the shrimp to survive and counteract the consequences of the stress.

Automated summary

This study explores the effects of ammonia stress on the molecular structure and functions of hemocyanin in Penaeus vannamei. The results show that ammonia stress alters the molecular structure of hemocyanin, affects its protein and oxyhemocyanin levels, and induces phosphorylation modification and degradation. Under moderate ammonia stress, hemocyanin undergoes glycosylation, leading to improved antibacterial activity and binding with different bacteria.