Intraspecific variation in the duration of epigenetic inheritance

Area of Science:

• Genetics
• Epigenetics
• Molecular Biology

Background:

• Epigenetic inheritance, particularly gene silencing via small RNAs, is crucial for transgenerational memory.
• The natural variation and evolutionary impact of epigenetic inheritance mechanisms remain largely unexplored.

Purpose of the Study:

• To investigate the genetic variation in the presence and duration of epigenetic inheritance within a species.
• To determine if DNA sequence polymorphisms influence epigenetic memory duration.
• To assess the impact of environmental factors on epigenetic memory.

Main Methods:

• Utilized the nematode Caenorhabditis elegans for studying RNA interference (RNAi) and transgenerational gene silencing.
• Compared epigenetic memory duration across various wild strains of C. elegans.
• Analyzed the effects of natural DNA sequence variations (e.g., in set-24 and drh-1 genes) and environmental factors (diet, diapause, temperature) on silencing memory.

Main Results:

• Significant variation in the presence and duration of epigenetic silencing was observed across C. elegans wild strains.
• Several wild strains exhibited no memory, while others displayed longer memory than the reference strain.
• Natural DNA sequence polymorphisms in genes like set-24 and drh-1 were found to affect epigenetic memory duration.
• Epigenetic memory duration was robust to variations in diet and larval diapause but sensitive to temperature changes.

Conclusions:

• Intraspecific diversity exists in the regulation of small RNA-based heredity.
• Genetic variation in DNA sequences directly impacts the duration of epigenetic inheritance.
• This diversity provides a basis for natural selection acting on genetic variants that modulate epigenetic inheritance.