Comparative distribution of a putative egg-laying hormone in neural and reproductive tissues of four Decapoda crustaceans

Evidence for the presence of a putative egg-laying (ELH) hormone has been previously described in the black tiger shrimp, Penaeus monodon, so a further investigation was carried out to detect its presence in a range of Decapoda crustaceans prior to a full molecular analysis. The crustaceans were represented by the Australian fresh water yabbie, Cherax destructor, the Australian southern rock lobster, Jasus edwardsii, the snow crab, Chionoecetes opilio, and the blue swimmer crab, Portunus pelagicus. Female cerebral ganglia, ventral nerve cords and gonads were investigated in a comparative study of the distribution of the immunoreactive hormone using immunoenzyme and immunofluorescence techniques. Immunoreactivity was detected in all tissues of interest, and the distribution patterns showed similarity within the four species, as well as that of P. monodon reported in the earlier study. There were minor variations. These data indicate that a putative ELH-like neuropeptide is widespread in crustaceans, and supports its previous identification in a range of molluscs and other invertebrates. Elucidation of the molecular structure of the peptide hormone and its encoding gene, as well as its involvement in spawning behaviour of crustaceans, is now fully under investigation.