Upregulation of olfactory-related neuropeptide transcripts in male Macrobrachium rosenbergii in correlation to pheromone perception from molting females.

Our previous studies revealed a mating attractant or possibly a pheromone released from molting reproductive mature female prawns, Macrobrachium rosenbergii, stimulates the expression of insulin-like androgenic gland hormones in a co-culture system. The released attractant is perceived by olfactory receptors with setae located on the short lateral antennules (slAn), which connect to the olfactory neuropil in the central nervous system (CNS) of male prawns. This neural signaling propagating through the CNS is mediated by at least four neuropeptides, namely neuropeptide F (NPF), short NPF (sNPF), tachykinin (TK), and allatostatin-A (ATS-A) whose transcripts have been detected in the present study. These deduced sequences, along with their conserved domains, serve as signatures of the identified neuropeptides, which were then compared with those found in other crustaceans and insects, whose nucleotide sequences were obtained from the nucleotide database. RT-PCR identified the expressions of the transcripts encoding these neuropeptides in the CNS. In situ hybridization specifically localized these transcripts in olfactory-associated neurons of cluster 9/11 of the deutocerebrum. Quantitative real-time PCR was used to quantify the expressions of the transcripts in response to the female attractants under different co-culture conditions: males with molting females (G1), males with intermolt females (G2), and slAn ablated males with molting females (G3). The transcripts were significantly increased on days 4-8 in the brain (Br) of males in G1 but not in G2 and G3. This suggests that expressions of the transcripts encoding the neuropeptides are associated with the perception of female mating pheromones through the slAn. This study is the first to show that female mating chemicals regulate the expressions and abundance of the olfactory neuropeptides, thus providing valuable insights for manipulation of mating of this species in aquaculture production.