Microorganisms in the terrestrial deep biosphere host up to 20% of the earth's biomass and are suggested to be sustained by the gases hydrogen and carbon dioxide. A metagenome analysis of three deep subsurface water types of contrasting age (from <20 to several thousand years) and depth (171 to 448 m) revealed phylogenetically distinct microbial community subsets that either passed or were retained by a 0.22 μm filter. Such cells of <0.22 μm would have been overlooked in previous studies relying on membrane capture. Metagenomes from the three water types were used for reconstruction of 69 distinct microbial genomes, each with >86% coverage. The populations were dominated by Proteobacteria, Candidate divisions, unclassified archaea and unclassified bacteria. The estimated genome sizes of the <0.22 μm populations were generally smaller than their phylogenetically closest relatives, suggesting that small dimensions along with a reduced genome size may be adaptations to oligotrophy. Shallow ‘modern marine' water showed community members with a predominantly heterotrophic lifestyle. In contrast, the deeper, ‘old saline' water adhered more closely to the current paradigm of a hydrogen-driven deep biosphere. The data were finally used to create a combined metabolic model of the deep terrestrial biosphere microbial community.
Epigenetic alteration has been implicated in aging. However, the mechanism by which epigenetic change impacts aging remains to be understood. H3K27me3, a highly conserved histone modification signifying transcriptional repression, is marked and maintained by Polycomb Repressive Complexes (PRCs). Here, we explore the mechanism by which age-modulated increase of H3K27me3 impacts adult lifespan. Using Drosophila, we reveal that aging leads to loss of fidelity in epigenetic marking and drift of H3K27me3 and consequential reduction in the expression of glycolytic genes with negative effects on energy production and redox state. We show that a reduction of H3K27me3 by PRCs-deficiency promotes glycolysis and healthy lifespan. While perturbing glycolysis diminishes the pro-lifespan benefits mediated by PRCs-deficiency, transgenic increase of glycolytic genes in wild-type animals extends longevity. Together, we propose that epigenetic drift of H3K27me3 is one of the molecular mechanisms that contribute to aging and that stimulation of glycolysis promotes metabolic health and longevity.
Background Loss-of-function mutations in Nav1.5 cause sodium channelopathies, including Brugada syndrome (BrS), dilated cardiomyopathy (DCM), and sick sinus syndrome (SSS), however, no effective therapy exists. MOG1 increases plasma membrane (PM) expression of Nav1.5 and sodium current (INa) density, thus we hypothesize that MOG1 can serve as a therapeutic target for sodium channelopathies. Methods and Results Knockdown of MOG1 expression using siRNAs reduced Nav1.5 PM expression, decreased INa densities by 2-fold in HEK/Nav1.5 cells and nearly abolished INa in mouse cardiomyocytes. MOG1 did not affect Nav1.5 PM turnover. MOG1 siRNAs caused retention of Nav1.5 in endoplasmic reticulum, disrupted the distribution of Nav1.5 into caveolin3-enriched microdomains, and led to redistribution of Nav1.5 to non-caveolin-rich domains. MOG1 fully rescued the reduced PM expression and INa densities by Nav1.5 trafficking defective mutation D1275N associated with SSS/DCM/atrial arrhythmias. For BrS mutation G1743R, MOG1 restored the impaired PM expression of the mutant protein, and restored INa in a heterozygous state (mixture of wild-type and mutant Nav1.5) to a full level of a homozygous wild-type state. Conclusions Use of MOG1 to enhance Nav1.5 trafficking to PM may be a potential personalized therapeutic approach for some patients with BrS, DCM and SSS in the future.
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