The 18S rRNA Methyltransferase DIMT-1 Regulates Lifespan in the Germline Later in Life.

Ribosome heterogeneity has emerged as an important regulatory control feature for determining which proteins are synthesized, however, the influence of age on ribosome heterogeneity is not fully understood. Whether mRNA transcripts are selectively translated in young versus old cells and whether dysregulation of this process drives organismal aging is unknown. Here we examined the role of ribosomal RNA (rRNA) methylation in maintaining appropriate translation as organisms age. In a directed RNAi screen, we identified the 18S rRNA N6'-dimethyl adenosine (m6,2A) methyltransferase, dimt-1, as a regulator of C. elegans lifespan and stress resistance. Lifespan extension induced by dimt-1 deficiency required a functional germline and was dependent on the known regulator of protein translation, the Rag GTPase, raga-1, which links amino acid sensing to the mechanistic target of rapamycin complex (mTORC)1. Using an auxin-inducible degron tagged version of dimt-1, we demonstrate that DIMT-1 functions in the germline after mid-life to regulate lifespan. We further found that knock-down of dimt-1 leads to selective translation of transcripts important for stress resistance and lifespan regulation in the C. elegans germline in mid-life including the cytochrome P450 daf-9, which synthesizes a steroid that signals from the germline to the soma to regulate lifespan. We found that dimt-1 induced lifespan extension was dependent on the daf-9 signaling pathway. This finding reveals a new layer of proteome dysfunction, beyond protein synthesis and degradation, as an important regulator of aging. Our findings highlight a new role for ribosome heterogeneity, and specific rRNA modifications, in maintaining appropriate translation later in life to promote healthy aging.

Soil microbiome dataset from Guanica dry forest in Puerto Rico generated by shotgun sequencing.

Guanica dry forest (GDF), located in the southwest area or region of Puerto Rico, is among the most preserved subtropical dry forests in the world [1]. To describe the taxonomic diversity and functional profiles of this environment, metagenomic DNA was extracted from a metagenomic library generated from the GDF. The DNA was shotgun-sequenced using Illumina and analyzed using the MG-RAST server. The diversity profile revealed that the most abundant domain was Bacteria (97.8%) followed by Archaea (1.12%), Eukaryota (1.02%) and Viruses (0.03%). Out of the 50 phyla present, the most abundant was Proteobacteria (41.6%) followed by Actinobacteria (18.7%) and Acidobacteria (7.06%). Moreover, a total of 213 orders, 384 families and 791 genus were identified. The functional profile showed abundance of genes related to Carbohydrates (13.16%), Clustering-based subsystems (13.0%), Amino Acids and Derivatives (9.9%) and Protein Metabolism (8.24%). Furthermore, more specific grouping showed that NULL (21.5%) was the most abundant function group, followed by Plant-Prokaryote DOE project (6.05%), Protein biosynthesis (4.82%), Central carbohydrate metabolism (3.98%), DNA repair (2.72%) and Resistance to antibiotics and toxic compounds (2.66%). This dataset is useful in bioprospecting studies with application in biomedical sciences, biotechnology and microbial, population and applied ecology fields.