Feeding recombinant Royalactin: Measures of improved lifespan and mitochondrial function in Caenorhabditis elegans

Ageing, the decline of biological functions over time, is inherent to eukaryotes. Female honeybees attain a long-lived queen phenotype upon continuous consumption of royal jelly, whereas restricted supply of this nutritional substance promotes the development of worker bees, which are short-lived. An abundant protein found within royal jelly is major royal jelly protein 1 (MRJP1), also known as ‘Royalactin’. Health- and lifespan promoting effects have been attributed to Royalactin in species from diverse animal taxa, suggesting it acts on phylogenetically conserved physiological processes. Here, we explore the effects of feeding the nematode Caenorhabditis elegans with Escherichia coli that express a recombinant form of Royalactin (RArec). We confirm that consumption of RArec increases body size, improves locomotion and extends lifespan. We discover a link between Royalactin and mitochondria, organelles which play a key part in the ageing process: both spare respiratory capacity and morphology indicate improved mitochondrial function in RArec fed C. elegans . These results demonstrate the feasibility of using recombinant Royalactin to gain further insight into processes of healthy ageing in many species. RArec production allows insight into potential beneficial effects across species. ### Competing Interest Statement The authors have declared no competing interest.