Transcriptomic Changes Following Induced De-Masculinisation of Australian Red Claw Crayfish Cherax quadricarinatus

Abstract

The Australian red claw crayfish Cherax quadricarinatus, an emerging species within the freshwater aquaculture trade, is not only an ideal species for commercial production due to its high fecundity, fast growth, and physiological robustness but also notoriously invasive. Investigating the reproductive axis of this species has been of great interest to farmers, geneticists, and conservationists alike for many decades; however, aside from the characterisation of the key masculinising insulin-like androgenic gland hormone (IAG) produced by the male-specific androgenic gland (AG), little remains known about this system and the downstream signalling cascade involved. This investigation used RNA interference to silence IAG in adult intersex C. quadricarinatus (Cq-IAG), known to be functionally male but genotypically female, successfully inducing sexual redifferentiation in all individuals. To investigate the downstream effects of Cq-IAG knockdown, a comprehensive transcriptomic library was constructed, comprised of three tissues within the male reproductive axis. Several factors known to be involved in the IAG signal transduction pathway, including a receptor, binding factor, and additional insulin-like peptide, were found to not be differentially expressed in response to Cq-IAG silencing, suggesting that the phenotypic changes observed may have occurred through post-transcriptional modifications. Many downstream factors displayed differential expression on a transcriptomic level, most notably related to stress, cell repair, apoptosis, and cell proliferation. These results suggest that IAG is required for sperm maturation, with necrosis of arrested tissue occurring in its absence. These results and the construction of a transcriptomic library for this species will inform future research involving reproductive pathways as well as biotechnological developments in this commercially and ecologically significant species.

Monosex Populations of the Giant Freshwater Prawn Macrobrachium rosenbergii—From a Pre-Molecular Start to the Next Generation Era

“…In M. rosenbergii, MrDsx expression was significantly induced in the testis and AG following eyestalk ablation, and gene knockdown of MrDsx resulted in a significant decrease in MrIAG transcript levels in the AG, suggesting that eyestalk elements negatively control MrDsx, which regulates the activation of MrIAG [77]. As part of the extensive research aimed at elucidating the IAG signaling cascade in decapod species, IAG loss-of-function studies have played a significant role in the understanding of the IAG downstream factors [78][79][80][81][82][83]. Still, in most of the studies on candidates upstream of the IAG-switch, it seems that the intervention (usually RNAi) is too late to effectively influence sexual differentiation.…”