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Natural probiotics improve heritable sterility

Summary

Scientists discovered that some worms naturally carry mutations that cause progressive sterility across generations when raised in standard laboratory conditions. However, when these same worms are exposed to their naturally associated bacteria and parasites, they regain the ability to reproduce normally. This suggests that the microorganisms living with worms help regulate how genetic information is passed down through generations, and the bacteria diet can even create protective effects that last for multiple generations.

Background

The mortal germline (Mrt) phenotype, characterized by progressive sterility over multiple generations, occurs in C. elegans wild isolates when cultured in standard laboratory conditions with E. coli OP50. This phenotype results from mutations in genes involved in small RNA pathways and chromatin modification, leading to aberrant epigenetic memory inheritance.

Objective

To investigate why the Mrt phenotype is prevalent in wild C. elegans isolates despite its deleterious fitness effects, and to determine whether naturally associated microbes can suppress this phenotype.

Results

Over half of tested wild isolates showed Mrt phenotype at 25°C. Worms with their natural microbial fauna did not exhibit sterility, but bleaching to remove microbes restored the phenotype. K-12 bacterial strains partially rescued Mrt, and diet-induced epigenetic memory persisted for multiple generations after returning to OP50.

Conclusion

Natural microbes and microsporidia suppress the Mrt phenotype through gene-diet interactions that modulate epigenetic reprogramming. These findings suggest that Mrt variants are maintained through balancing selection in wild populations and behave neutrally in natural environments but show deleterious effects in laboratory conditions.
  • Published in:EMBO Reports,
  • Study Type:Review/Commentary,
  • Source: 10.15252/embr.202358318, PMID: 37983676
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