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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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187 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Investigating the Relationship between the Cell Wall Integrity Pathway and Unfolded Protein Response

Plants have made significant contributions to astronaut health in spaceflight missions. To further spaceflight research in optimizing plant viability, this study aims to understand the factors involved in maintaining cell wall integrity, which is vital to plant morphology and structural stability. Spaceflight can negatively impact the cell wall; thus, it is crucial to investigate how to mitigate spaceflight stressors to maintain the integrity of the cell wall. The structural integrity of plants’ cell walls depends on secondary cell wall biogenesis, which enables the repair and architectural support of plants like A. thaliana. This biogenesis is triggered by a signal transduction cascade: first initiated by cell wall stress, the CWI (cell wall integrity) pathway is activated, followed by the UPR (unfolded protein response), then the cell wall’s integrity is maintained through secondary cell wall biogenesis. Through a re-analysis of GeneLab Dataset 321 (GLDS-321), a study from NASA’s Open Science Data Repository that investigates the effects of spaceflight on the UPR, several genes were found to be associated with the cell wall. This proposal postulates a relationship between the UPR and the CWI pathway and their direct effect on secondary cell wall biogenesis by investigating IRX7, a gene associated with secondary cell wall biogenesis. The predicted outcome of overexpressing IRX7 is increased resilience of the cell wall by upregulating both the UPR and the CWI pathway, while silencing IRX7 is predicted to compromise the cell wall integrity by downregulating the UPR and the CWI pathway. This study will give insight into the needed measures to increase cell wall resilience in stressful environments: As spaceflight durations increase and uncertain climate change events progress on Earth, understanding how to optimize cell wall resilience – a fundamental pillar of plant health – can effectively enhance mass crop production and quality and ensure the physical and psychological health of astronauts in long-term space missions.

GL4HS↗
NASA NTRS2023

T-Cell Shenanigans: The Impact of MHC Pathway & Lipid Metabolism Genes on T-Cell Differentiation in the Thymus

Astronaut health and proper immune function are key to the success and sustainability of long term missions in space. While previous studies have observed adaptive immune dysfunction such as diminished WBC counts and cytokine production during spaceflight, the underlying mechanisms behind why immune function worsens are poorly understood. Using transcriptomic data analyzed from mouse thymus tissues available from the GLDS-421 experiment on the Rodent Research-9 mission, we used the GeneLab standardized RNA-Seq pipeline and identified four genes that were largely dysregulated (p<0.05): lipid metabolic genes Hpgd and Pgr and cell cycle regulator genes Cenpe and Kif11. We analyzed how these genes regulate the MHC-TCR interaction, and used this understanding to propose a novel mechanism for alterations to T-cell differentiation. In our experimental methodology, we propose to use 36 transgenic CD4-CD8 mice and 12 wild-type mice from the Jackson Lab to create a microgravity-simulating hindlimb unloading model and test our hypothesis. By silencing the aforementioned genes using custom siRNA based primers, we will use flow cytometry and RNA-Seq to quantify Treg counts in comparison to naive CD4+ cells, Alamar Blue assay for observing the metabolic activity in T-cells, and Enzyme-Linked Immunosorbent Assay (ELISA) to observe the general immune response in terms of T-cell differentiation. We hope this methodology will improve our knowledge of MHC-TCR interaction, contribute to a better understanding of the mechanisms of autoimmune diseases such as lupus, and improve the success rate of newer cancer treatments such as CAR-T cell therapy.

GL4HS↗
DOE OSTI2021

Gold-Nanocluster-Mediated Delivery of siRNA to Intact Plant Cells for Efficient Gene Knockdown

RNA interference, which involves the delivery of small interfering RNA (siRNA), has been used to validate target genes, to understand and control cellular metabolic pathways, and to use as a "green" alternative to confer pest tolerance in crops. Conventional siRNA delivery methods such as viruses and Agrobacterium -mediated delivery exhibit plant species range limitations and uncontrolled DNA integration into the plant genome. Here, we synthesize polyethylenimine-functionalized gold nanoclusters (PEI-AuNCs) to mediate siRNA delivery into intact plants and show that these nanoclusters enable efficient gene knockdown. We further demonstrate that PEI-AuNCs protect siRNA from RNase degradation while the complex is small enough to bypass the plant cell wall. Consequently, AuNCs enable gene knockdown with efficiencies of up 76.5 ± 5.9% and 76.1 ± 9.5% for GFP and ROQ1, respectively, with no observable toxicity. Our data suggest that AuNCs can deliver siRNA into intact plant cells for broad applications in plant biotechnology.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

A Thermosensitive, Phase-Variable Epigenetic Switch: pap Revisited

It has been more than a decade since the last comprehensive review of the phase-variable uropathogen-associated pyelonephritis-associated pilus (pap) genetic switch. Since then, important data have come to light, including additional factors that regulate pap expression, better characterization of H-NS regulation, the structure of the Lrp octamer in complex with pap regulatory DNA, the temperature-insensitive phenotype of a mutant lacking the acetyltransferase RimJ, evidence that key components of the regulatory machinery are acetylated, and new insights into the role of DNA binding by key regulators in shaping both the physical structure and regulatory state of the papI and papBA promoters. This review revisits pap, integrating these newer observations with older ones to produce a new model for the concerted behavior of this virulence-regulatory region.

gene silencing↗
NASA NTRS2003

A lignin-specific peroxidase in tobacco whose antisense suppression leads to vascular tissue modification

A tobacco peroxidase isoenzyme (TP60) was down-regulated in tobacco using an antisense strategy, this affording transformants with lignin reductions of up to 40-50% of wild type (control) plants. Significantly, both guaiacyl and syringyl levels decreased in essentially a linear manner with the reductions in lignin amounts, as determined by both thioacidolysis and nitrobenzene oxidative analyses. These data provisionally suggest that a feedback mechanism is operative in lignifying cells, which prevents build-up of monolignols should oxidative capacity for their subsequent metabolism be reduced. Prior to this study, the only known rate-limiting processes in the monolignol/lignin pathways involved that of Phe supply and the relative activities of cinnamate-4-hydroxylase/p-coumarate-3-hydroxylase, respectively. These transformants thus provide an additional experimental means in which to further dissect and delineate the factors involved in monolignol targeting to precise regions in the cell wall, and of subsequent lignin assembly. Interestingly, the lignin down-regulated tobacco phenotypes displayed no readily observable differences in overall growth and development profiles, although the vascular apparatus was modified.

NASA Program Fundamental Space Biology↗