Rotifers are a potentially valuable new model to investigate the mechanisms of aging, as well as homeostasis and tissue regeneration, the effects of reproductive mode (asexual versus sexual) on longevity, and the cellular and molecular processes of senescence. Moreover, as basal metazoans, rotifers may share more genes with humans than Ecdyzoan animal models like C. elegans and D. melanogaster. In the proposed work we identify new genes associated with rotifer aging and search for their homologs in humans. Monogonont rotifers have specific features that make them an attractive models for aging studies, including: 1) a history of aging related research extending back nearly a century; 2) asexual propagation of clonal cultures, so that experiments can take place in the same genetic background, without the potential inbreeding depression imposed on isogenic lines; 3) sexual and asexual reproduction in the same genetic background; 4) haploid males, allowing direct expression of alleles and simplifying crosses in the absence of complex marker chromosomes; 5) production of highly stable diapausing eggs; 5) many closely related strains and species that differ in life history traits; and 6) A well developed tool box of genetic resources including partially sequenced genomes and transcriptomes, and a working RNAi protocol. In the proposed work, we determine the effects on aging and longevity of dietary restriction, oxidative stress, and elevated temperature in five closely related strains of the Brachionus plicatilis species complex. The effect of sexual and asexual reproduction on aging also is investigated and correlated with cumulative oxidative damage to proteins, lipids, and DNA. We also identify genes involved in aging and longevity by examining the transcription profiles of rotifers of different ages under different dietary, reproductive, and stress conditions, and confirm the activity of specific genes by RNAi and qtPCR. The role of diapause in aging also is investigated by examining the mechanisms by which diapause in Brachionus alters tissue homeostasis, suspends metabolism during dormancy, and stimulates tissue repair following dormancy. The degree of aging observed in rotifers that have been kept in a dormant state for up to 25 years also is examined. PUBLIC HEALTH RELEVANCE: Rotifers are a valuable new invertebrate model to investigate the mechanisms of aging, including homeostasis and tissue regeneration, the effects of reproductive mode (asexual versus sexual) and diapause on longevity, and the cellular and molecular processes of senescence. Because of their phylogenetic relationship to humans and other animals, they can be useful in the identification of genes that regulate aging. Identifying evolutionarily conserved genes in Ecdysozoan and spiralian phyla that regulate organismal aging could provide attractive targets for pharmacological intervention in mammalian aging. Molecular understanding of how dietary restriction extends lifespan will have direct implications for new approaches to treat metabolic diseases like diabetes and obesity.