Molecular Characterization and Functional Analysis of Pomacea canaliculata Mos Gene (PcMos): A Molecular Switch of Female Fecundity

The invasive Pomacea canaliculata has emerged as a notorious pest that endangers aquatic crops, ecological services and functioning. Although well-documented as a mammalian oocyte maturation factor, the biological roles of Moloney sarcoma oncogene (Mos) in invertebrates, notably P. canaliculata, remain unfathomed. We integrated RNA interference (RNAi)-mediated gene silencing alongside bioinformatic, molecular, biochemical and histological approaches to dissect fecundity-related functions and modulatory mechanisms of PcMos at the mRNA, protein and in silico levels. Characterized by the conserved protein kinase domain and motif, the PcMos protein sequence presented close phylogeny with its molluscan counterparts. Spatiotemporal expression profiling showed that mRNA and protein levels of PcMos were enriched in female adults and ovarian tissues. Efficient in vivo RNAi effects were induced as the transcription and translation of PcMos significantly declined by 78.2% and 79.0%, respectively, following a microinjection of 5 μg dsPcMos per female post 48 h. The downstream MAPK pathway, comprising MEK1, ERK1 and p90RSK1, was depressed when subjected to dsPcMos treatment, as reflected by pronounced decreases in mRNA and phosphorylated protein levels. Substantial diminution of E2/Pg/LH/FSH contents were noticed in the PcMos-RNAi group versus the dsEGFP group, suggesting fundamental implications of PcMos in endocrine regulation. In addition, the concurrent expression and high affinity between PcMos and VTG were visualized by the immunofluorescence and molecular docking, which may be associated with the diminished VTG content and expression upon PcMos silencing. Moreover, PcMos knockdown led to impaired ovarian development and reduced SP content, the number ofmature oocytes, egg production and egg-hatching rates. Taken together, our findings pointed to PcMos as a molecular switch pivotal for female fecundity, potentially acting through coordinated effects on MAPK signaling, endocrine hormone homeostasis and yolk deposition. This study may inspire the precision pest management and inform the design of RNAi-based sterility agents to suppress P. canaliculata populations.