Biology subjects

Ram, R.

Publications and source records attributed to Ram, R..

3 recordsLinked to original sources

bioRxiv2023

Multiomic single-cell sequencing defines tissue-specific responses in Stevens-Johnson Syndrome and Toxic epidermal necrolysis.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is a rare but life-threatening cutaneous drug reaction mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T-cells. To obtain an unbiased assessment of SJS/TEN cellular immunopathogenesis, we performed single-cell (sc) transcriptome, surface proteome, and TCR sequencing on unaffected skin, affected skin, and blister fluid from 17 SJS/TEN patients. From 119,784 total cells, we identified 16 scRNA-defined subsets, confirmed by subset-defining surface protein expression. Keratinocytes upregulated HLA and IFN-response genes in the affected skin. Cytotoxic CD8+ T-cell subpopulations of expanded and unexpanded TCR{beta} clonotypes were shared in affected skin and blister fluid but absent or unexpanded in SJS/TEN unaffected skin. SJS/TEN blister fluid is a rich reservoir of oligoclonal CD8+ T-cells with an effector phenotype driving SJS/TEN pathogenesis. This multiomic database will act as the basis to define antigen-reactivity, HLA restriction, and signatures of drug-antigen-reactive T-cell clonotypes at a tissue level.

immunology↗

bioRxiv2023

Metabolic adaptations and aquifer connectivity underpin the high productivity rates in the relict subsurface water

BackgroundDiverse microbes catalyze biogeochemical cycles in the terrestrial subsurface, yet the corresponding ecophysiology was only estimated in a limited number of subterrestrial, often shallow aquifers. Here, we detrained the productivity, diversity, and functions of active microbial communities in the Judea Group carbonate and the underlying deep (up to 1.5 km below ground) Kurnub Group Nubian sandstone aquifers. These pristine oligotrophic aquifers, recharged more than tens to hundreds of thousands years ago, contain fresh/brackish, hypoxic/anoxic, often hot (up to 60{degrees}C) water and serve as habitats for key microbial producers. ResultsWe show that recent groundwater recharge, inorganic carbon and ammonium strongly influence chemosynthetic primary productivity in carbonate and sandstone aquifers (4.4-21.9 {micro}g C d-1 L-1 and 1.2-2.7 {micro}g C d-1 L-1, respectively). These high values indicate the possibility that the global aquifer productivity rates may be underestimated. Metagenome analysis revealed the prevalence of chemoautotrophic pathways, particularly the Calvin-Benson-Bassham cycle. The key chemosynthetic lineages in the carbonate aquifer were Halothiobacillales, whereas Burkholderiales and Rhizobiales occupied the sandstone aquifer. Most chemosynthetic microbes may oxidize sulfur compounds or ammonium, using oxygen or oxidized nitrogen as electron acceptors. Abundant sulfate reducers in the anoxic deeper aquifer have the potential to catabolize various organics, fix carbon via the Wood Ljungdahl pathway, and often possess nitrogenase, indicating diazotrophic capabilities. Our data suggest that connectivity between the aquifers and their exposure to energy inputs and surface water may play a key role in shaping these communities, altering physicochemical parameters and selecting taxa and functions. We highlight the metabolic versatility in the deep subsurface that underpins their efficient harnessing of carbon and energy from different sources.

microbiology↗

bioRxiv2022

Increased H3K27 trimethylation contributes to cone survival in a mouse model of cone dystrophy

Inherited retinal diseases (IRDs) are a heterogeneous group of blinding disorders, which result in dysfunction or death of the light-sensing cone and rod photoreceptors. Despite individual IRDs being rare, collectively, they affect up to 1:2000 people worldwide, causing a significant socioeconomic burden, especially when cone-mediated central vision is affected. This study uses the Pde6ccpfl1 mouse model of achromatopsia, a cone-specific vision loss IRD, to investigate the potential gene-independent therapeutic benefits of a histone demethylase inhibitor GSK-J4 on cone cell survival. We investigated the effects of GSK-J4 treatment on cone cell survival in vivo and ex vivo and changes in cone-specific gene expression via single-cell RNA sequencing. A single intravitreal GSK-J4 injection led to transcriptional changes in pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, among other key epigenetic pathways, highlighting the complex interplay between methylation and acetylation in healthy and diseased cones. Furthermore, continuous administration of GSK-J4 in retinal explants increased cone survival. Our results suggest that IRD-affected cones respond positively to epigenetic modulation of histones, indicating the potential of this approach in the development of a broad class of novel therapies to slow cone degeneration.

neuroscience↗