Genome‐wide association and environmental suppression of the mortal germline phenotype of wild C. elegans

Abstract

The animal germline lineage needs to be maintained along generations. However, some Caenorhabditis elegans wild isolates display a mortal germline phenotype, leading to sterility after several generations at 25°C. Using a genome‐wide association approach, we detect a significant peak on chromosome III around 5 Mb, confirmed by introgressions. Thus, a seemingly deleterious genotype is maintained at intermediate frequency in the species. Environmental rescue is a likely explanation, and indeed associated bacteria and microsporidia suppress the phenotype of wild isolates as well as mutants in small RNA inheritance (nrde‐2) and histone modifications (set‐2). Escherichia coli strains of the K‐12 lineage suppress the phenotype compared to B strains. By shifting a wild strain from E. coli K‐12 to E. coli B, we find that memory of the suppressing condition is maintained over several generations. 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.

Natural variation in infection specificity ofCaenorhabditis briggsaeisolates by two RNA viruses

“…Altogether, we noted an initial increase in viral sensitivity after CRISPR genome, which was abolished along further experiments (Table S7). This possible transient effect may parallel previous observations on CRISPR replacement assays for the mortal germline phenotype (Frézal et al 2023). We do not know whether this may be a gene-specific or aspecific effect of oligonucleotide and/or Cas9 injections.…”

Natural variation in infection specificity of Caenorhabditis briggsae isolates by two RNA viruses

“…Altogether, we noted an initial increase in viral sensitivity after CRISPR genome, which was abolished along further experiments ( S7 Table ). This possible transient effect may parallel previous observations on CRISPR replacement assays for the mortal germline phenotype [ 67 ], in which the initial phenotype of the edited line was lost over time when several assays were conducted in successive blocks. We do not know whether this may be a gene-specific or aspecific effect of oligonucleotide and/or Cas9 injections.…”

Naturally-associated bacteria modulate Orsay virus infection of Caenorhabditis 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 [14][15][16][36][37][38], which for short will be referred to as "natural bacteria", many of which were isolated in locations where the Orsay virus was also found. We primarily investigated bacterial strains from the phylum Pseudomonadota.…”