GFSKLYFamide-like neuropeptide is expressed in the female gonad of the sea cucumber, Holothuria scabra

Neuropeptides are mediators of neuronal signalling, controlling a wide range of physiological processes that cut across many organisms. GFSKLYFamide is a neuropeptide that belongs to the Echinoderm SALMFamide group of peptides. This study was aimed at determining the expression of GFSKLYFamide-like neuropeptide in the female gonad of the sea cucumber Holothuria scabra. Ten female H. scabra weighing between 62 and 175 g were collected at different times between May, 2009 and April, 2010 from the Andaman Sea at Koh Jum Island in Krabi province of Thailand for the study. Using GFSKLYFamide polyclonal antibody and Alexa 488-conjugated goat anti-rabbit IgG as primary and secondary antibodies, respectively, indirect immunofluorescence method and confocal microscope was used to localise GFSKLYFamide-like immunoreactivity in the female gonad of H. scabra. The results show GFSKLYFamide-like immunoreactivity being expressed in the sub-epithelial fibres of the coelomic epithelium. This is the first report providing evidence of GFSKLYFamide neuropeptide existence in the female gonad of H. scabra. It was suggested that further studies be carried out to investigate if there is similar existence of GFSKLYFamide neuropeptide in male gonad of H. scabra and also to know the structure or activity of the peptide(s) producing GFSKLYFamide-like immunoreactivity in H. scabra gonads.   Key words: GFSKLYFamide, SALMFamides, immunoreactivity, sea cucumber, echinoderm, gonad.