Male sexual development and the androgenic gland: novel insights through the de novo assembled transcriptome of the eastern spiny lobster, Sagmariasus verreauxi

The Eastern spiny lobster, <i>Sagmariasus verreauxi</i>, is commercially important in fisheries, with growing aquaculture potential, driving an interest to better understand male sexual differentiation. Amongst the Decapoda<i>, </i>the androgenic gland (AG) and the insulin-like androgenic gland hormone (IAG) have a well-defined function in male sexual differentiation. However, IAG is not a sex determinant and therefore must be considered as part of a broader, integrated pathway. This work uses a transcriptomic, multi-tissue approach to provide an integrated description of male-biased expression as mediated through the AG. Transcriptomic analyses demonstrate that IAG expression is stage- and eyestalk-regulated (low in immature, high in mature and 6-times higher in hypertrophied glands), with IAG being the predominant AG-specific factor. The low expression of this key factor in immature males suggests the involvement of other tissues in male sexual differentiation. Across tissues, the gonad (87.8%) and antennal gland (73.5%) show the highest male-biased differential expression of transcripts and also express 4 sex-determination regulators, known as <i>Dmrts</i>, with broader expression of<i> Sv-Sxl </i>and <i>Sv-TRA-2.</i> In order to better understand male sexual differentiation, tissues other than the AG must also be considered. This research highlights the gonad and antennal gland as showing significant male-biased expression patterns, including the <i>Sv-Dmrts</i>.