C. elegans possess a general program to enter cryptobiosis that allows dauer larvae to survive different kinds of abiotic stress

Abstract

All organisms encounter abiotic stress but only certain organisms are able to cope with extreme conditions and enter into cryptobiosis (hidden life). Previously, we have shown that C. elegans dauer larvae can survive severe desiccation (anhydrobiosis), a specific form of cryptobiosis. Entry into anhydrobiosis is preceded by activation of a set of biochemical pathways by exposure to mild desiccation. This process called preconditioning induces elevation of trehalose, intrinsically disordered proteins, polyamines and some other pathways that allow the preservation of cellular functionality in the absence of water. Here, we demonstrate that another stress factor, high osmolarity, activates similar biochemical pathways. The larvae that acquired resistance to high osmotic pressure can also withstand desiccation. In addition, high osmolarity significantly increases the biosynthesis of glycerol making larva tolerant to freezing. Thus, to survive abiotic stress, C. elegans activates a combination of genetic and biochemical pathways that serve as a general survival program.

LEA motifs promote desiccation tolerancein vivo

“…In a daf-2(e1370) background, we confirmed that both lea-1Δ and lea-1(tm6452) dauer worms were sensitive to desiccation at high relative humidity (97.5%) and at a more stringent desiccation stress of 60% humidity (Fig. 2A), consistent with published results [10, 29, 30]. Additionally, dauer worms of each of these mutant strains were sensitive to osmotic stress in a concentrated salt solution.…”

“…Previous studies have relied on RNAi for gene knockdown and did not fully eliminate lea-1 mRNA [10] or noted that RNAi seldom fully eliminates the target mRNA [29]. One recent study used a deletion allele, but only confirmed the phenotype of desiccation sensitivity [30]. Furthermore, there are many isoforms of LEA-1 (Fig.…”

“…One recent study used a deletion allele, but only confirmed the phenotype of desiccation sensitivity [30]. Furthermore, there are many isoforms of LEA-1 (Fig.…”

“…C. elegans survive many stresses including desiccation, have a well-resourced genetic toolkit, and contain two LEA family proteins, lea-1 and dur-1 ( d auer u p-regulated) [10, 29]. Disruption of lea-1 has been reported to sensitize worms to desiccation, osmotic stress with sucrose, and larval heat stress [10, 29, 30]. dur-1 is also required for a robust desiccation response but is apparently unable to compensate for the loss of LEA-1 [29].…”

Quantitative imaging ofCaenorhabditis elegansdauer larvae during cryptobiotic transition using optical diffraction tomography

“…However, when encountering a harsh environment, overcrowding or food scarcity, C. elegans pauses the reproductive cycle and enters diapause by forming a non-feeding dauer larva (6). It has been shown that this dauer larva can survive severe desiccation (5), high osmotic pressure, or freezing (7). The dauer larvae differ from reproductive larvae in both metabolism and morphology (6,8).…”