Expression and functional analysis of the Akt gene from Daphnia pulex

Daphnia pulex is a nutrient-rich freshwater crustacean with two different reproduction methods. Akt is a serine/threonine protein kinase that plays an important role in cell growth, survival, and lifespan regulation. To explore the function of Akt in the growth and aging process of Daphnia pulex, we cloned the cDNA sequence of the open reading frame (ORF) of the akt gene based on the bioinformatic analysis of the transcriptome data of D. pulex, and analyzed the structural features of the Akt protein. Gene silencing was performed using RNA interference (RNAi), and the expression of the Akt gene and protein before and after interference were analyzed using qPCR and western blotting. The results showed that the expression of akt in D. pulex at different ages showed a “W” pattern, being significantly higher at 20 days than at 10 days and 15 days (P < .05). The expression trend of Akt protein and mRNA were similar, with lower expression at a younger age (1–5 day), after which expression gradually increased from 10 days age, and showed no significant change after 25 days, which might be caused by a lag of protein translation. RNAi reduced the expression of the Akt gene and protein by at least 76%, and the survival rate and reproductive capacity of D. pulex were significantly lower in the RNAi group compared with those in the control group. This study provides a better understanding of the function of the akt gene in D. pulex.