The occurrence of luteinizing hormone-like molecule and its receptor in the blue swimming crab, Portunus pelagicus.

Knowledge of the neuroendocrine system possibly improves the reproductive performance of captivated crustacean broodstock in aquaculture and it may substitute eyestalk ablation. In this study, we explored the luteinizing hormone (LH)-like molecule and proved the existence of the LH receptor (PpelLHR)-like mRNA in the blue swimming crab, Portunus pelagicus. Using the anti-human LH-β antibody, the immunoreactivities were found in the central nervous system (CNS) and ovary of the crab with the strongest signal in the mature ovary. The full-length PpelLHR-like mRNA sequence contained 4818 bp with deduced protein predicted as seven transmembrane G-protein coupled receptor, made of 1605 amino acids. The phylogenetic tree suggested this protein belonged to the clade of invertebrate LHR/FSHR-like proteins. The PpelLHR-like mRNA expressed in various organs and real-time qPCR revealed significantly higher expression of this mRNA in the brain and lower expression in the ovary of the mature crabs. In situ hybridization of this mRNA was demonstrated in neuronal clusters of the brain, ventral nerve cord, and in the oocyte stage 1-4 of the ovary, respectively. This study was preliminary to prove the existence of LH and its receptor in the blue swimming crab. Functional assay of this receptor should be performed as the next part of experiments to firmly conclude its appearance.