Since the development of Mendelian genetics in the 1870s, the classical principles of genetics based on DNA sequence and the Epigenetic inheritance principles based on DNA/histone modification have been widely accepted and become the basic theories of genetics. However, in addition to DNA, non-coding small RNAs have also been found to function as genetic material and determine a variety of epigenetic traits.
C.elegans are the classical model system for studying small RNAs, some of which in can transfer information across generations. Prof. Oded Rechavi-led team at Tel Aviv University has discovered three rules that control transgenerational inheritance via small RNA molecules in C.elegans, challenging our traditional concepts regarding the limits of inheritance and evolution:
First rule: Inheritance is uniform in worms descending from the same mother – namely worms of the same lineage. Differences in inheritance were “concealed” because they had examined whole worm populations rather than distinct lineages.
Second rule: Inheritance is different in worms from different mothers, even though the mothers are supposedly identical. This is because the descendants randomly adopt different “internal states” that determine the duration of inheritance and thus the fate of subsequent generations.
Third rule: The longer the duration of the epigenetic inheritance – namely, the greater the number of generations in a specific lineage who inherits the trait – the greater the number of generations in a specific lineage that inherits a trait, the greater the probability that it will continue on to the next generation as well.
1. Rechavi, O., and Lev, I. (2017). Principles of Transgenerational Small RNA Inheritance in Caenorhabditis elegans. Curr Biol 27, R720-R730.
2. Houri-Zeevi, L., Kohanim, YK., Antonova, O., Rechavi, O. (2020). Three Rules Explain Transgenerational Small RNA Inheritance in C. elegans. Cell 182, 1186-1197.
3. Acquired traits may be transmitted to future generations - TAU study. Retrieved August 27, 2020 from Jerusalem Post.