Identification of the Potential Functions of the PKA-R1 Gene in the Regulation of Growth Performance and Molting of Macrobrachium nipponense by RNAi

Macrobrachium nipponense holds significant economic importance in freshwater aquaculture in China, where larger body weight and longer body length are directly associated with higher market demand and improved commercial value. Consequently, identifying genes associated with growth traits is a priority for enhancing economic returns. Previous studies have predicted that the cAMP-dependent protein kinase type I regulatory subunit-like (PKA-R1) may be involved in the growth regulation of M. nipponense. In this study, we functionally characterized the Mn-PKA-R1 gene to investigate its potential involvement in growth and molting regulation in M. nipponense through qPCR analysis and RNA interference (RNAi). The open reading frame of Mn-PKA-R1 spanned 3345 base pairs, encoding a protein of 1114 amino acids. The Mn-PKA-R1 amino acid sequence showed the highest identity with that of Macrobrachium rosenbergii, followed by Penaeus vannamei. Tissue distribution analysis revealed that Mn-PKA-R1 was ubiquitously expressed across all examined tissues, with the highest transcript level detected in the testis, suggesting a potential association with testis-related physiological functions. Functional validation via RNA interference showed that repeated dsPKA-R1 treatment was associated with reduced molting frequency and relative body weight compared with the non-targeting dsRNA control group. From day 14 to day 42, the relative body weight compared with day 0 in the non-targeting dsRNA control group was significantly higher than that in the dsPKA-R1-injected group. Additionally, the molting frequency in the non-targeting dsRNA control group was significantly higher than that in the dsPKA-R1-injected group at days 7, 14, 21, 28, and 35. These findings suggest that Mn-PKA-R1 may participate in the regulation of growth and molting in M. nipponense under the tested experimental conditions. This study provides preliminary functional evidence for the involvement of Mn-PKA-R1 in growth-related traits in M. nipponense.