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Abstract

Caenorhabditis elegans worms produce and keep imprints of the attractive chemosensory cues to which they are exposed early in life. Imprinting enhances transiently or permanently chemoattraction to early olfactory cues.  I will show that when stably inherited, olfactory imprints segregate in the progeny as monoallelic marks following Mendelian laws.  
Olfactory imprinting can be transferred from odor-exposed to naive worms via RNA feeding. Biochemical fractionation of RNA identified the tRNAAla (UGC) as the unique olfactory imprinting molecule. Indeed tRNAAla (UGC) extracted from odor-exposed woms transfers odor-specific imprints, suggesting odor-stimuli trigger tRNAAla (UGC) changes.
Mutations in the Elongator complex sub-units 1 or 3 either impair all chemo-attractive responses or stably suppress odor-specific responses after odor-exposure. Elongator is a very conserved (from yeast to human) complex involved in many biological/developmental functions, including tRNA processing. Naive wild-type tRNAAla (UGC) rescue both behavioral phenotypes of Elongator mutants.
Worm chemoattractive responses are epigentically controlled by the olfactory environment, via the tRNAAla (UGC) and the Elongator complex activity.
I will discuss how tRNAs, their fragments and their genes are involved in a growing number of biological functions.