Effects of prohibitin on ageing process and reproduction of Daphnia pulex

Daphnia pulex is considered as a great natural food for aquaculture, and Prohibitin (PHB) is a functional protein that plays a key role in eukaryotic cell activities such as proliferation and ageing. To explore the function of PHB in the ageing process of Daphnia pulex (D. pulex), we cloned and analysed the full-length cDNA of phb1 and phb2. With the growth of D. pulex, expression of two genes have a N curve trend which raised up first and dropped then raised again. Western blot analysis revealed that expression of the PHB proteins increased from 1- to 10-day age, but did not significantly change from 10- to 35-day age. RNAi knockdown of phb1, reduced expression of phb2 and PHB protein, and significantly induced the expression of sex-determining related gene Doublesex (Dsx), and ageing-related pathway gene Protein kinase B (Akt). Longevity of the individuals in RNAi group was shortened to 45 days, which was significantly shorter than the other groups. Despite the growth was not significantly different, reproduction amount was significantly impacted by RNAi. These results suggest that PHB significantly affect ageing of D. pulex and may be involved in the reproductive transformation, leading to a decline of reproductive capacity. This study develops our understanding of the ageing mechanism in D. pulex as a potential model organism, provides further insight into the effect of PHB in the processes of ageing and expands our knowledge of molecular mechanisms on ageing and reproduction.