Multi-Omics Study of Tardigrade Ramazzottius Varieornatus Reveals Dynamic Metabolic Response During Anhydrobiosis

Limno-terrestrial tardigrades (water bears) can withstand almost complete desiccation through a mechanism called anhydrobiosis, and several of these species have been shown to survive the most extreme environments through exposure to space vacuum. Molecular mechanism for this tolerance has so far been studied in many anhydrobiotic metazoans, leading to the identification of several key molecules such as the accumulation and vitrification of trehalose as well as the expression of LEA proteins to prevent protein aggregation. On the other hand, the understanding of comprehensive molecular mechanisms and regulation machinery of metabolic compounds during anhydrobiosis is yet to be explored. To this end, we have conducted a comprehensive multi-omics analysis encompassing genomics, transcriptomics, metabolomics, and proteomics using the tardigrade Ramazzottius varieornatus, which is a potential model species for anhydrobiosis. Based on the reconstructed metabolic pathway maps assigned from over 19000 genes identified within the 60Mbp genome, using a combination of informatic pipelines, quantitative metabolome and proteome data were systematically analyzed to elucidate the complex cellular response upon desiccation. While changes in gene expression profiles are limited in between active and tun states, dynamic changes were observed in the metabolism of this species in response to desiccation. Changes in the metabolic profiles suggest complex intracellular responses to oxidative and osmotic stress.