Timing for Male Reproductive Tract Gene Expression and Gonopore Complex Development of Giant Freshwater Prawn (Macrobrachium rosenbergii)

Mono-sex culture of giant freshwater prawns (Macrobrachium rosenbergii) gives more benefits than mixed-sex culture because of high market demand for male prawns. Unfortunately, sex differentiation in crustaceans could not obviously be observed in their early larval stage. Therefore, sex segregation or sex reversal techniques need to be developed and timing for sex differentiation in M. rosenbergii during larval development needs to be examined. In this study, three genes related to male reproductive hormone (IAG, MRR and MAL) were isolated and amplified from terminal ampulae (TA) of adult male M. rosenbergii. The male specific transcripts demonstrated that they could be used to monitor sex differentiation time during larval development. Observation of male transcripts expression together with macro and microscopic pictures of phenotypic characters, the appendix masculina (AP) and the gonopore complex (GP), during larval and juvenile development demonstrated that the sex differentiation process of male freshwater prawns began when the larvae were 2 months old or after complete metamorphosis. Moreover, this is the first report on SEM depicting an ultra-valve like structure on gonopore complex surface during sex development of male prawn.