Crustacean cardioactive peptide (CCAP) of the Pacific white shrimp (Litopenaeus vannamei): Molecular characterization and its potential roles in osmoregulation and freshwater tolerance

Osmoregulation is one of the most fundamental and delicately controlled processes in euryhaline marine species like penaeid shrimp. Here we first report a cDNA encoding for the crustacean cardioactive peptide (CCAP) precursor cloned from the intestine of Pacific white shrimp, Litopenaeus vannamei, a prominent commercial culture species. The CCAP mature peptide (PFCNAFTGC-NH2) is generated by post-translational processing and found to be highly comparable with its counterparts in insects and other crustaceans. Semi-quantitative RT-PCR reveals that L. vannamei CCAP (Lv-CCAP) mRNA is predominantly expressed in the brain and intestine. However, only the expression level of intestine-derived Lv-CCAP mRNA showed responsiveness to salinity changes in culture. The inducible expressed Lv-CCAP mRNA by transfer to high-salinity condition was continuous, while mRNA expression stimulated by transfer to low-salinity condition was transient. Functionally, the stimulatory effects of CCAP on heart rates in the shrimp cultured in low-and normal-salinity conditions were confirmed. Furthermore, injection of CCAP could up-regulate the freshwater tolerance of shrimp by increasing their survival rates. Our study, as a whole, provides new insights into hormone-regulated crustacean osmostasis and may prove instructive to the inland freshwater penaeid shrimp aquaculture. State of relevance It proves instructive to freshwater shrimp aquaculture. (C) 2015 Elsevier B.V. All rights reserved.