Starvation changes the pre-rRNA accumulations in Caenorhabditis elegans.

Abstract

The precursor rRNA (pre-rRNA) processing pathway in Caenorhabditis elegans remains unidentified. We have determined the cleavage site within the internal transcribed spacer 2, which generates pre-rRNA f of 5.8S rRNA and pre-rRNA g of 26S rRNA. Ribosome biogenesis is the most energetically demanding process of the cell. Under starved conditions, cells conserve energy by reconfiguring ribosome biogenesis to sustain proper growth. We investigated the short-term effects of starvation on the ribosomal RNA (rRNA) maturation in C. elegans. Northern blot analysis revealed significant changes in both small and large pre-rRNAs, with a substantial decrease in pre-rRNA c'1/27SA₂ of the large subunit and an increase in pre-rRNA d of the small subunit. Additionally, most pre-rRNAs accumulated in the nucleolar center, while the rRNA maturation factor FIB-1 accumulated at the nucleolar periphery. Nutritional replenishment restored the pre-rRNA accumulation pattern and the distribution of pre-rRNAs in the nucleolus to pre-starvation conditions.