Kazan Federal University, RIKEN
Genome under extreme desiccation: system biology of anhydrobiosis
An African chironomid Polypedilum vanderplanki is the only insect that developed unique mechanism to cope with extreme desiccation. Larvae of this insect withstand more than 97% of water loss by entering in ametabolic state called anhydrobiosis. Intensive studies using Polypedilum vanderplanki during the last decade, revealed the key mechanisms underlying this unique adaptation: replacement water with sugar trehalose, presence of unique groups of protective proteins, and complex biochemistry processes associated with anhydrobiosis. Sequencing of the genomes of the x-midge and closely-related species of midges, opened a new era of the study of anhydrobiosis. Comparative analysis of the x-midge genomes showed clear modifications, including birth of whole new regions in the genome, where novel protective genes are located, associated with acquiring the ability to withstand complete water loss. Now, using the most advanced method of RNA analysis we move toward understanding of the tissue- and cell-specific adaptations to dry. Recent establishment of the cell lines, derived from the embryonic cells of the larvae and surviving complete desiccation in vitro, gives a strong hope to establishing innovative methods of preservation of the living materials alive without water. We have developed an atlas of tissue-specific single-nucleotide level maps of promoters and enhancers of x-midge. We found that there is clear tissue specific patter of expression of the unique protective genes sets in response to desiccation. Furthermore, our recent data derived from single cell transcriptomics suggest that cells successfully surviving complete water loss would have a unique transcriptional profile. In my talk I will also introduced some unanswered questions we face, including those of origin and evolution of the protective genes in the midge and interplay among gene expression and metabolism under deficit of water.