Insight into the Regulatory Relationships between the Insulin-Like Androgenic Gland Hormone Gene and the Insulin-Like Androgenic Gland Hormone-binding Protein Gene in Giant Freshwater Prawns ( Macrobrachium rosenbergii ).

Giant freshwater prawns (Macrobrachium rosenbergii) are commonly found throughout the world. The size of the male giant freshwater prawn is much larger than that of the female. Therefore, understanding the molecular mechanism that underlies the sexual differentiation ofM. rosenbergiiis of both commercial and scientific importance. Insulin-like androgenic gland hormone (IAG) plays a key role in the differentiation of sex inM. rosenbergii. Although IAG has been investigated, the regulatory relationship between IAG and its binding protein partner, the insulin-like androgenic gland hormone-binding protein (IAGBP), has not been studied inM. rosenbergii. Here, we cloned and characterized theIAGBPfromM. rosenbergii(Mr-IAGBP) for the very first time. Transcriptomic analysis showed thatMr-IAGBPmRNA was detected in a wide array of tissues with the highest expression found in the androgenic gland. The importance ofIAGin male development was further demonstrated by an increase inIAGtranscripts during the development of the androgenic gland andMr-IAGwas only highly transcribed in the androgenic gland ofM. rosenbergii. Interestingly, we found that theMr-IAGgene expression started during the 20th-day larva after hatching stage (LH20), followed (20th-day post-larval stage, PL20) by a gradual elevation ofMr-IAGBPlevels. The levels of both genes peaked at the adult stage. The relationship betweenMr-IAGBPandMr-IAGwas further analyzed using RNA interference. The injection ofMr-IAGBPdouble-stranded RNA (dsRNA) significantly reduced the transcription ofMr-IAG, while the amount ofMr-IAGBPmRNA and the translation of IAGBP protein was significantly reduced by the injection ofMr-IAGdsRNA. These results revealed that IAGBP is involved in IAG signaling. Furthermore, our data supports the hypothesis that (IAG and IAGBP)-IAG receptor signaling schemes exist inM. rosenbergii. Our results will provide important information for the further study of determining the sex ofM. rosenbergii.