Abstract
Some organisms can withstand complete body water loss (losing up to 99% of body water) and stay in ametabolic state for decades until rehydration, which is known as anhydrobiosis. Few multicellular eukaryotes on their adult stage can withstand life without water. We still have an incomplete understanding of the mechanism for metazoan survival of anhydrobiosis. Here we report the 255-Mb genome of Aphelenchus avenae, which can endure relative zero humidity for years. Gene duplications arose genome-wide and contributed to the expansion and diversification of 763 kinases, which represents the second largest metazoan kinome to date. Transcriptome analyses of ametabolic state of A. avenae indicate the elevation of ATP level for global recycling of macromolecules and enhancement of autophagy in the early stage of anhydrobiosis. We catalogue 74 species-specific intrinsically disordered proteins, which may facilitate A. avenae to survive through desiccation stress. Our findings refine a molecular basis evolving for survival in extreme water loss and open the way for discovering new anti-desiccation strategies.
Highlights
Some organisms can withstand complete body water loss and stay in ametabolic state for decades until rehydration, which is known as anhydrobiosis
Massive horizontal gene transfer (HGT) events were identified in bdelloid rotifer Adineta vaga genome[2,5], whereas no extensive HGT was found in tardigrade Ramazzottius varieornatus and Hypsibius dujardini genomes[3,4,6]
We estimated the genome size of A. avenae to be 255 Mb based on flow cytometry analysis, which is 2.5 times the size of Caenorhabditis elegans
Summary
Some organisms can withstand complete body water loss (losing up to 99% of body water) and stay in ametabolic state for decades until rehydration, which is known as anhydrobiosis. 2 TEDA Institute of Biological Sciences and water is essential for life, certain organisms, across the three kingdoms of life, can survive extreme water loss by entering ametabolic state, known as anhydrobiosis, in the certain stage of life cycle (e.g., metazoan larvae or/and adult stage)[1]. Nonreducing trehalose and late embryogenesis abundant (LEA) proteins were proposed to act synergistically to form gel-phase bioglass in anhydrobiotic A. avenae[18,20] It is not completely understood how the genetic changes in the evolution of anhydrobiotic nematodes enable resistance to complete desiccation and how A. avenae reprograms its cells state in different dehydration stages for survival in complete water loss. Comparative genomic and transcriptomic analyses will help understand general and species-specific molecular mechanisms for complex animal to survive in extreme water loss
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