Genome-wide association and environmental suppression of the mortal germline phenotype of wildC. elegans

Abstract

The animal germline lineage needs to be maintained along generations. However, some Caenorhabditis elegans wild isolates display a mortal germline phenotype, whereby the lineage becomes sterile after several generations at 25C. We used a genome-wide association approach to study the genetic basis for this phenotype in C. elegans populations. We detected a significant peak on chromosome III around 5 Mb, which was confirmed using introgression lines. These results indicate that a seemingly deleterious genotype is maintained at intermediate frequency in the species. Environmental rescue is a likely explanation and we indeed find that naturally associated bacteria and microsporidia suppressed the phenotype. The tested bacteria also suppressed the temperature-sensitive mortal germline phenotype of mutants in small RNA inheritance (nrde-2) and histone modifications (set-2). Even Escherichia coli strains of the K-12 lineage suppressed the phenotype compared to B strains. By shifting a strain cultured on E. coli K-12 back to E. coli B, we found that C. elegans can keep over several generations the memory of the suppressing conditions. Thus, the mortal germline phenotype of wild C. elegans is in part revealed by laboratory conditions and may represent variation in epigenetic inheritance and environmental interactions. This study also points to the importance of non-genetic memory in the face of environmental variation.

A natural bacterial pathogen ofC. elegansuses a small RNA to induce transgenerational inheritance of learned avoidance

“…These studies revealed multiple features of the microbiota in C. elegans natural habitat and their relationship to host physiology (Dirksen et al, 2020;Zhang et al, 2017). Studying bacterial species that are naturally associated with C. elegans might reveal processes that occur in the wild, and not in the laboratory, and vice versa; for example, bacteria from C. elegans' natural environment suppress mortal germline phenotypes that wild worms exhibit on laboratory strains of E. coli (Lise Frézal et al, 2023). Therefore, it is important to test the physiological relevance of laboratory experimental results under more natural conditions.…”

Natural monobacterial environments modulate viral infection inCaenorhabditis elegans

“…In this study, we investigated the effect of bacterial environments on C. elegans susceptibility to OrV. We focused on monocultures of bacterial clones isolated from C. elegans natural habitats (13,14,15,36,37). Our objective was to determine whether the bacterial environment affects the nematode's response to the virus and gain a deeper understanding of how specific bacterial strains may modulate host susceptibility to viruses.…”