Bacterial diet and weak cadmium stress affect the survivability of Caenorhabditis elegans and its resistance to severe stress

Abstract

Stress may have negative or positive effects in dependence of its intensity (hormesis). We studied this phenomenon in Caenorhabditis elegans by applying weak or severe abiotic (cadmium, CdCl2) and/or biotic stress (different bacterial diets) during cultivation/breeding of the worms and determining their developmental speed or survival and performing transcriptome profiling and RT-qPCR analyses to explore the genetic basis of the detected phenotypic differences. To specify weak or severe stress, developmental speed was measured at different cadmium concentrations, and survival assays were carried out on different bacterial species as feed for the worms. These studies showed that 0.1 μmol/L or 10 mmol/L of CdCl2 were weak or severe abiotic stressors, and that E. coli HT115 or Chitinophaga arvensicola feeding can be considered as weak or severe biotic stress. Extensive phenotypic studies on wild type (WT) and different signaling mutants (e.g., kgb-1Δ and pmk-1Δ) and genetic studies on WT revealed, inter alia, the following results. WT worms bred on E. coli OP50, which is a known cause of high lipid levels in the worms, showed high resistance to severe abiotic stress and elevated gene expression for protein biosynthesis. WT worms bred under weak biotic stress (E. coli HT115 feeding which causes lower lipid levels) showed an elevated resistance to severe biotic stress, elevated gene expression for the innate immune response and signaling but reduced gene expression for protein biosynthesis. WT worms bred under weak biotic and abiotic stress (E. coli HT115 feeding plus 0.1 μmol/L of CdCl2) showed high resistance to severe biotic stress, elevated expression of DAF-16 target genes (e.g., genes for small heat shock proteins) but further reduced gene expression for protein biosynthesis. WT worms bred under weak biotic but higher abiotic stress (E. coli HT115 feeding plus 10 μmol/L of CdCl2) showed re-intensified gene expression for the innate immune response, signaling, and protein biosynthesis, which, however, did not caused a higher resistance to severe biotic stress. E. coli OP50 feeding as well as weak abiotic and biotic stress during incubations also improved the age-specific survival probability of adult WT worms. Thus, this study showed that a bacterial diet resulting in higher levels of energy resources in the worms (E. coli OP50 feeding) or weak abiotic and biotic stress promote the resistance to severe abiotic or biotic stress and the age-specific survival probability of WT.

Comparative Small RNA Profiling and Functional Exploration on Wheat With High- and Low-Cadmium Accumulation

“…Therefore, in wheat, the target genes of our candidate small RNAs are correlated with the metabolism of cadmium, thereby validating our prediction. As for peptidyl-serine dephosphorylation, although few publications report the functional role of such biological processes in plants, in 2019, a specific study on Caenorhabditis elegans confirmed that such biological processes are correlated with weak cadmium stress via complex microbiological regulation, thereby validating our prediction (Dölling et al, 2019).…”

Newly identified nematodes from the Great Salt Lake are associated with microbialites and specially adapted to hypersaline conditions

“…We were curious if the increased survivability on GSL microbes was due to a general induction of stress response to a foreign bacterium. E. coli HT115 is a weak biotic stressor that, perhaps counterintuitively, can enhance survival of C. elegans under certain stressed conditions [ 51 ]. The laboratory strain of C. elegans (N2) fed on HT115 showed a mixed response to GSL water after 5 min (ANOVA, diet: Chi Sq = 0.0131, d.f.…”

Experimental variables that impact outcomes inCaenorhabditis elegansaging stress response

“…However, these experiments in the C. elegans stress response field lack standardization, creating results that are often difficult to interpret in the context of similar research. Experimental variables like stressor dose (e.g., acute vs. chronic), culture conditions, age at stress exposure, strain of bacterial food source, and method of stressor delivery can meaningfully impact the stressor dose needed to achieve a specific health outcome, activation of stress response pathways, and longevity of the organism [5–7], which can in turn significantly affect both experimental outcomes and biological interpretation of a study. This is particularly important for building an accurate understanding of biology of stress response by examining the body of evidence from experiments across different projects and laboratories.…”