An androgenic gland membrane-anchored gene associated with the crustacean insulin-like androgenic gland hormone

Abstract

SUMMARYCrustacean male sexual differentiation is governed by the androgenic gland (AG) and specifically by the secreted insulin-like AG hormone (IAG), thus far identified in several decapod species including the Australian red claw crayfish Cherax quadricarinatus (termed Cq-IAG). While a few insulin-like AG genes have been identified in crustaceans, other AG-specific genes have not been documented until now. In the present study, we describe the recent identification of a non-IAG AG-specific transcript obtained from the C. quadricarinatus AG cDNA library. This transcript, termed C. quadricarinatus membrane-anchored AG-specific factor (Cq-MAG), was fully sequenced and found to encode a putative product of 189 amino acids including a signal anchoring peptide. Expression of a recombinant GFP fusion protein lacking the signal anchor encoding sequence dramatically affected recombinant protein localization pattern. While the expression of the deleterious fusion protein was observed throughout most of the cell, the native GFP::Cq-MAG fusion protein was observed mainly surrounding the periphery of the nucleus, demonstrating an endoplasmic reticulum (ER)-like localization pattern. Moreover, co-expression of the wild-type Cq-MAG (fused to GFP) and the Cq-IAG hormone revealed that these peptides indeed co-localize. This study is the first to report a protein specifically associated with the insulin-like AG hormone in addition to the finding of another AG-specific transcript in crustaceans. Previous knowledge suggests that insulin/insulin-like factor secretion involves tissue-specific transcripts and membrane-anchored proteins. In this regard, Cq-MAGʼs tissue specificity, anchoring properties and intracellular co-localization with Cq-IAG suggest that it may play a role in the processing and secretion of this insulin-like AG hormone.

Detection and Control of Invasive Freshwater Crayfish: From Traditional to Innovative Methods

“…A technique studied for both aquaculture and invasive crayfish species is the "masculinization of individuals". The insulin-like androgenic gland hormone (IAG) plays a decisive role in sexual differentiation, with the possibility of manipulating crayfish populations in order to produce sexually altered populations, such as monosex populations, which will not reproduce further [127,128]. The potential of intervention through sex-change induction on established populations of NICS illuminates new management possibilities.…”

Male Sexual Development and the Androgenic Gland: Novel Insights through the de novo Assembled Transcriptome of the Eastern Spiny Lobster,<b><i> Sagmariasus verreauxi</i></b>

“…Amongst the annotated upregulated transcripts was an orthologue of a recently identified AG-specific transcript, characterized in C. quadricarinatus : the AG-specific membrane-anchored protein ( Cq-MAG ) [Rosen et al, 2013a]. However, in S. verreauxi , it appears that Sv-MAG is not AG-specific as it also shows expression in both testis and ovary [but not in male or female brain, eyestalk, antennal gland, hepatopancreas, or male muscle, as demonstrated through both RPKM (all <1) and RT-PCR analyses ( fig.…”

“…The work of Jin et al [2013] identified a total of 47 sex-related gene families in the AG of M. nipponense , clear evidence of the AG's function in sexual development. However, with the exception of the membrane-anchored AG-specific factor (Cq-MAG) characterized in Cherax quadricariantus [Rosen et al, 2013a], to our knowledge, besides IAG no other AG-specific factors have been characterized to date.…”

Multi-Tissue Transcriptome Analysis Identifies Key Sexual Development-Related Genes of the Ornate Spiny Lobster (Panulirus ornatus)

“…In addition to IAG , MAG is also broadly expressed. Given that MAG was found to directly interact with IAG [ 39 ], this broad expression further supports a more diverse role for IAG in reproduction and metabolism. Interestingly, MAG expression overlaps with that of ILP1 .…”

“…Upon secretion, IAG is chaperoned in the hemolymph by an insulin-like growth factor-binding peptide (IGFBP) which is abundantly expressed across tissues [ 13 , 38 ]. IAG secretion is further facilitated by a membrane-anchored AG-specific factor (MAG), identified initially in the redclaw crayfish Cherax quadricarinatus [ 39 ] and later in the eastern spiny lobster Sagmariasus verreauxi , where a slight expression in the gonads was also detectable [ 11 ]. Modeling analysis concluded that the neural-derived ILPs share the same binding characteristic to IGFBP as IAG [ 8 ], suggesting they might also compete with IAG for receptor binding.…”