Analysis of candidate gene expression patterns of adult male Macrobrachium rosenbergii morphotypes in response to a social dominance hierarchy

In this study, we investigated the relative gene expression pattern of 12 candidate genes from giant freshwater prawn (GFP) using hepatopancreas, eyestalk and testis tissues to compare expression profiles among adult male morphotypes [blue claw (BC), orange claw (OC) and small males (SM)] that reflect a social hierarchy. In particular, we focused our analysis on genes documented in other invertebrate taxa that are known to influence (i) inter-male aggressive behaviour, (ii) visual systems and (iii) olfactory genes. Genes examined here were normalised to 18S rRNA as a reference. Differences in gene expression patterns among male morphotypes and tissues were highly significant (P<0.0001) with higher expression levels in eyestalk tissue compared with testis and hepatopancreas in all morphotypes. This might imply that differences in expression pattern of key candidate genes in the eyestalk can potentially provide cues to directly influence the formation of the male social dominance hierarchy. Expression stabilities of genes were evaluated using the RefFinder analytical tool, which revealed that STRPC-short transient receptor and BDP-beadex dlmo protein showed relatively similar expression levels. LW OPSIN, a visual system gene, appeared to be directly involved in suppression of subordinate male gene expression related to the social dominance hierarchy in male GFP. This finding could potentially be important for developing technologies that allow male morph frequencies to be manipulated at harvest in farmed stocks.