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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Branched-chain amino acid specialization drove diversification within Calditenuaceae ( Caldarchaeia ) and enables their cultivation

Many thermophiles that are abundant in high-temperature geothermal systems have never been cultivated and are poorly understood, including deeply branching members of the archaeal phylum Thermoproteota. Here, we describe the genome-guided cultivation of one such organism, Calditenuis ramacidaminiphagus, and show that it has evolved a heterotrophic metabolism focused on branched-chain amino acids (BCAAs). Initially, fluorescence in situ hybridization and nanoscale secondary ion mass spectrometry (FISH-nanoSIMS) showed that Cal. ramacidaminiphagus assimilated amino acids rapidly in casamino acid-amended enrichment cultures. Metagenome and metaproteome analyses showed a high abundance and expression of BCAA transporter genes, suggesting a BCAA-focused metabolism. This inference was supported by the subsequent enrichment of Cal. ramacidaminiphagus in BCAA-fed cultures, reaching 2.66×10 6 cells/mL and 48.7% of the community, whereas it was outcompeted when polar amino acids were included. Metabolic reconstruction and metaproteomics suggest that BCAAs are channeled into the mevalonate pathway for lipid biosynthesis and fuel ATP production through the TCA cycle coupled with aerobic respiration and through production of branched-chain organic acids by overflow metabolism. Ancestral state reconstructions and phylogenetic analyses of 62 Caldarchaeales genomes revealed multiple horizontal transfers of BCAA transporters to the ancestor of the genus Calditenuis. Our study highlights the crucial role of BCAAs in the early evolution and niche of this genus, and suggests a high degree of resource partitioning even within low-diversity thermophilic communities.

Biological and medical sciences↗
NASA NTRS1978

The organism and the habitation atmosphere

Experimental data is examined on the study of the influence of the different parameters of the atmosphere on the organism for the purpose of making a physiological determination of the permissible oxygen concentrations in inhabited airtight compartments. The application of high oxygen concentrations for respiration and for medical purposes are considered. Data is presented on the evolution of the atmosphere and of the role of O2 in the process of the evolutionary development of living beings; the influence of an organism of an artificial, high and low oxygen concentration atmospheres; the laws of oxygen permeation into fluid media of the organism; the biological role of inert gases; etc. The relationship between the gas medium of habitation and reactivity of the organism is determined.

Agadzhanyan, N. A.↗
NASA NTRS2002

Influence of microgravity on astronauts' sympathetic and vagal responses to Valsalva's manoeuvre

When astronauts return to Earth and stand, their heart rates may speed inordinately, their blood pressures may fall, and some may experience frank syncope. We studied brief autonomic and haemodynamic transients provoked by graded Valsalva manoeuvres in astronauts on Earth and in space, and tested the hypothesis that exposure to microgravity impairs sympathetic as well as vagal baroreflex responses. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in four healthy male astronauts (aged 38-44 years) before, during and after the 16 day Neurolab space shuttle mission. Astronauts performed two 15 s Valsalva manoeuvres at each pressure, 15 and 30 mmHg, in random order. Although no astronaut experienced presyncope after the mission, microgravity provoked major changes. For example, the average systolic pressure reduction during 30 mmHg straining was 27 mmHg pre-flight and 49 mmHg in flight. Increases in muscle sympathetic nerve activity during straining were also much greater in space than on Earth. For example, mean normalized sympathetic activity increased 445% during 30 mmHg straining on earth and 792% in space. However, sympathetic baroreflex gain, taken as the integrated sympathetic response divided by the maximum diastolic pressure reduction during straining, was the same in space and on Earth. In contrast, vagal baroreflex gain, particularly during arterial pressure reductions, was diminished in space. This and earlier research suggest that exposure of healthy humans to microgravity augments arterial pressure and sympathetic responses to Valsalva straining and differentially reduces vagal, but not sympathetic baroreflex gain.

Non-NASA Center↗
NASA NTRS2000

Physiologic Responses Produced by Active and Passive Personal Cooling Vests

Personal thermoregulatory systems which provide chest cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to document and compare the subjects' response to three cooling vests in their recommended configurations. The Life Enhancement Tech (LET) lightweight active cooling vest with cap, the MicroClimate Systems Change of Phase garment (MCS), and the Steele Vest were each used to cool the chest regions of 12 male and 8 female Healthy subjects (21 to 69 yr.) in this study. The subjects, seated in an upright position at normal room temperature (approx. 22 C), were tested for 60 min. with one of the cooling garments. The LET active garment had an initial coolant fluid inlet temperature of 60 F, and was ramped down to 50 F. Oral, right and left ear canal temperatures were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; and respiration were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. For men, all three vests had similar, significant cooling effects. Decreases in the average rectal temperature, oral temperature, and ear canal temperatures were approximately 0.2 C, 0.2 C and 0.1 C, respectively. In contrast to the men, the female subjects wearing the MCS and Steel vests had similar cooling responses in which the core temperature remained elevated and oral and ear canal temperatures did not drop. The LET active garment cooled most of the female subjects in this study; rectal, oral and ear temperature decreased about 0.2 C, 0.3 C and 0.3 C, respectively. These results show that the garment configurations tested do not elicit a similar thermal response in all subjects. A gender difference is evident. The LET active garment configuration was most effective in decreasing temperatures of the female subjects; the MCS vest was least effective. For male subjects, the three vests appear to be more nearly equivalent. The active garment system under study included a cooling cap, which may account for some of the difference in response.

Ku, Yu-Tsuan E.↗
DOE OSTI2022

mTOR regulates aerobic glycolysis through NEAT1 and nuclear paraspeckle-mediated mechanism in hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is a major form of liver cancer and a leading cause of cancer-related death worldwide. New insights into HCC pathobiology and mechanism of drug actions are urgently needed to improve patient outcomes. HCC undergoes metabolic reprogramming of glucose metabolism from respiration to aerobic glycolysis, a phenomenon known as the ‘Warburg Effect’ that supports rapid cancer cell growth, survival, and invasion. mTOR is known to promote Warburg Effect, but the underlying mechanism(s) remains poorly defined. The aim of this study is to understand the mechanism(s) and significance of mTOR regulation of aerobic glycolysis in HCC. We profiled mTORC1-dependent long non-coding RNAs (lncRNAs) by RNA-seq of HCC cells treated with rapamycin. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were used to explore the transcriptional regulation of NEAT1 by mTORC1. [U- 13 C]-glucose labeling and metabolomic analysis, extracellular acidification Rate (ECAR) by Seahorse XF Analyzer, and glucose uptake assay were used to investigate the role of mTOR-NEAT1-NONO signaling in the regulation of aerobic glycolysis. RNA immunoprecipitation (RIP) and NONO-binding motif scanning were performed to identify the regulatory mechanism of pre-mRNA splicing by mTOR-NEAT1. Myristoylated AKT1 (mAKT1)/NRASV 12 -driven HCC model developed by hydrodynamic transfection (HDT) was employed to explore the significance of mTOR-NEAT1 signaling in HCC tumorigenesis and mTOR-targeted therapy. mTOR regulates lncRNA transcriptome in HCC and that NEAT1 is a major mTOR transcriptional target. Interestingly, although both NEAT1_1 and NEAT1_2 are down-regulated in HCC, only NEAT1_2 is significantly correlated with poor overall survival of HCC patients. NEAT1_2 is the organizer of nuclear paraspeckles that sequester the RNA-binding proteins NONO and SFPQ. We show that upon oncogenic activation, mTORC1 suppresses NEAT1_2 expression and paraspeckle biogenesis, liberating NONO/SFPQ, which in turn, binds to U5 within the spliceosome, stimulating mRNA splicing and expression of key glycolytic enzymes. This series of actions lead to enhanced glucose transport, aerobic glycolytic flux, lactate production, and HCC growth both in vitro and in vivo. Furthermore, the paraspeckle-mediated mechanism is important for the anticancer action of US FDA-approved drugs rapamycin/temsirolimus. These findings reveal a molecular mechanism by which mTOR promotes the ‘Warburg Effect’, which is important for the metabolism and development of HCC, and anticancer response of mTOR-targeted therapy.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1972

Evidence for a metabolic limitation of survival in hypothermic hamsters.

The underlying factors limiting survival in the hypothermic state are studied. Hamsters of both sexes, clipped and unclipped, were inducted into profound hypothermia by the helium cold method until they reached a temperature between 7 and 10 C. It appears that the primary cause of death is failure of respiration due to the depletion of carbohydrate energy supplies and may explain why survival time in hypothermia is shorter than the normal hibernation time of the hamster.

Prewitt, R. L.↗
NASA NTRS1987

Possible role of brain stem respiratory neurons in mediating vomiting during space motion sickness

The object of this study was to determine if brain stem expiratory neurons control abdominal muscle activity during vomiting. The activity of 27 ventral respiratory group expiratory neurons, which are known to be of primary importance for control of abdominal muscle activity during respiration, was recorded. It is concluded that abdominal muscle activity during vomiting must be controlled not only by some brain stem expiratory neurons but also by other input(s).

Miller, A. D.↗
NASA NTRS1996

NASA's Biomass Production Chamber: a testbed for bioregenerative life support studies

The Biomass Production Chamber (BPC) located at Kennedy Space Center, FL, USA provides a large (20 m2 area, 113 m3 vol.), closed environment for crop growth tests for NASA's Controlled Ecological Life Support System (CELSS) program. Since the summer of 1988, the chamber has operated on a near-continuous basis (over 1200 days) without any major failures (excluding temporary power losses). During this time, five crops of wheat (64-86 days each), three crops of soybean (90 to 97 days), five crops of lettuce (28-30 days), and four crops of potato (90 to 105 days were grown, producing 481 kg of dry plant biomass, 196 kg edible biomass, 540 kg of oxygen, 94,700 kg of condensed water, and fixing 739 kg of carbon dioxide. Results indicate that total biomass yields were close to expected values for the given light input, but edible biomass yields and harvest indices were slightly lower than expected. Stand photosynthesis, respiration, transpiration, and nutrient uptake rates were monitored throughout growth and development of the different crops, along with the build-up of ethylene and other volatile organic compounds in the atmosphere. Data were also gathered on system hardware maintenance and repair, as well as person-hours required for chamber operation. Future tests will include long-term crop production studies, tests in which nutrients from waste treatment systems will be used to grow new crops, and multi-species tests.

NASA Center KSC↗
NASA NTRS1996

Higher sympathetic nerve activity during ventricular (VVI) than during dual-chamber (DDD) pacing

OBJECTIVES: We determined the short-term effects of single-chamber ventricular pacing and dual-chamber atrioventricular (AV) pacing on directly measured sympathetic nerve activity. BACKGROUND: Dual-chamber AV cardiac pacing results in greater cardiac output and lower systemic vascular resistance than does single-chamber ventricular pacing. However, it is unclear whether these hemodynamic advantages result in less sympathetic nervous system outflow. METHODS: In 13 patients with a dual-chamber pacemaker, we recorded the electrocardiogram, noninvasive arterial pressure (Finapres), respiration and muscle sympathetic nerve activity (microneurography) during 3 min of underlying basal heart rate and 3 min of ventricular and AV pacing at rates of 60 and 100 beats/min. RESULTS: Arterial pressure was lowest and muscle sympathetic nerve activity was highest at the underlying basal heart rate. Arterial pressure increased with cardiac pacing and was greater with AV than with ventricular pacing (change in mean blood pressure +/- SE: 10 +/- 3 vs. 2 +/- 2 mm Hg at 60 beats/min; 21 +/- 5 vs. 14 +/- 2 mm Hg at 100 beats/min; p < 0.05). Sympathetic nerve activity decreased with cardiac pacing and the decline was greater with AV than with ventricular pacing (60 beats/min -40 +/- 11% vs. -17 +/- 7%; 100 beats/min -60 +/- 9% vs. -48 +/- 10%; p < 0.05). Although most patients showed a strong inverse relation between arterial pressure and muscle sympathetic nerve activity, three patients with severe left ventricular dysfunction (ejection fraction < or = 30%) showed no relation between arterial pressure and sympathetic activity. CONCLUSIONS: Short-term AV pacing results in lower sympathetic nerve activity and higher arterial pressure than does ventricular pacing, indicating that cardiac pacing mode may influence sympathetic outflow simply through arterial baroreflex mechanisms. We speculate that the greater incidence of adverse outcomes in patients treated with single-chamber ventricular rather than dual-chamber pacing may be due in part to increased sympathetic nervous outflow.

NASA Discipline Cardiopulmonary↗
NASA NTRS1999

Electron-cytochemical study of Ca2+ in cotyledon cells of soybean seedlings grown in microgravity

Microgravity and horizontal clinorotation are known to cause the rearrangement of the structural-functional organization of plant cells, leading to accelerated aging. Altered gravity conditions resulted in an increase in the droplets volume in cells and the destruction of chloroplast structure in Arabidopsis thaliana plants, an enhancement of cytosolic autophagaous processes, an increase in the respiration rate and a greater number of multimolecular forms of succinate- and malate dehydrogenases in cells of the Funaria hygrometrica protonema and Chlorella vulgaris, and changes in calcium balance of cells. Because ethylene is known to be involved in cell aging and microgravity appears to speed the process, and because soybean seedlings grown in space produce higher ethylene levels we asked: 1) does an acceleration of soybean cotyledon cell development and aging occur in microgravity? 2) what roles do Ca2+ ions and the enhanced ethylene level play in these events? Therefore, the goal of our investigation was to examine of the interaction of microgravity and ethylene on the localization of Ca2+ in cotyledon mesophyll of soybean seedlings.

Flight Experiment↗
DOE OSTI2024

Accessing Fungal Contributions to the Birch Effect: Real-Time Respiration from Pore-Scale Microfluidics

Drying and rewetting of soil stimulates soil carbon emission. The Birch effect, driven by these cycles, leads to CO2 efflux, which can be monitored using real-time mass spectrometry (RTMS). Although soil fungi retain water during droughts, their contribution to CO2 release during drying–rewetting cycles remains unclear. In this study, we present the first demonstration of integrating micromodels with RTMS to monitor the Birch effect by simulating drought and rewetting. Micromodels were inoculated with axenic fungal culture and dried to assess moisture retention. After drying, RTMS quantified CO2 release upon rewetting with H218O mixtures. Our results showed that soil fungi released CO2 upon rehydration and immediately utilized the external water source at the pore scale by generating subsequent 46CO2. This work is the first to integrate RTMS with microsystems to investigate pore-scale biogeochemistry and the involvement of fungi in the Birch effect.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1999

Physiologic and thermal responses of male and female patients with multiple sclerosis to head and neck cooling

Personal cooling systems are used to alleviate symptoms of multiple sclerosis and to prevent increased core temperature during daily activities. The objective of this study was to determine the thermal and physiologic responses of patients with multiple sclerosis to short-term maximal head and neck cooling. A Life Support Systems, Inc. Mark VII portable cooling system and a liquid cooling helmet were used to cool the head and neck regions of 24 female and 26 male patients with multiple sclerosis in this study. The subjects, seated in an upright position at normal room temperature (approximately 22 degrees C), were cooled for 30 min by the liquid cooling garment, which was operated at its maximum cooling capacity. Oral, right, and left ear temperatures and cooling system parameters were logged manually every 5 min. Forearm, calf, chest, and rectal temperatures, heart rate, and respiration rate were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. This protocol was performed during the winter and summer to investigate the seasonal differences in the way patients with multiple sclerosis respond to head and neck cooling. No significant differences were found between the male and female subject group's mean rectal or oral temperature responses during any phase of the experiment. The mean oral temperature decreased significantly (P < 0.05) for both groups approximately 0.3 degrees C after 30 min of cooling and continued to decrease further (approximately 0.1-0.2 degrees C) for a period of approximately 15 min after removal of the cooling helmet. The mean rectal temperatures decreased significantly (P < 0.05) in both male and female subjects in the winter studies (approximately 0.2-0.3 degrees C) and for the male subjects during the summer test (approximately 0.2 degrees C). However, the rectal temperature of the female subjects did not change significantly during any phase of the summer test. These data indicate that head and neck cooling may, in general, be used to reduce the oral and body temperatures of both male and female patients with multiple sclerosis by the approximate amount needed for symptomatic relief as shown by other researchers. However, thermal response of patients with multiple sclerosis may be affected by gender and seasonal factors, which should be considered in the use of liquid cooling therapy.

NASA Discipline Environmental Health↗
DOE OSTI2024

Modeling microbial carbon fluxes and stocks in global soils from 1901 to 2016

Abstract. Soil microbes play a crucial role in the carbon (C) cycle; however, they have been overlooked in predicting the terrestrial C cycle. We applied a microbial-explicit Earth system model – the Community Land Model-Microbe (CLM-Microbe) – to investigate the dynamics of soil microbes during 1901 to 2016. The CLM-Microbe model was able to reproduce the variations of gross (GPP) and net (NPP) primary productivity, heterotrophic (HR) and soil (SR) respiration, microbial (MBC) biomass C in fungi (FBC) and bacteria (BBC) in the top 30 cm and 1 m, and dissolved (DOC) and soil organic C (SOC) in the top 30 cm and 1 m during 1901–2016. During the study period, simulated C variables increased by approximately 12 PgC yr−1 for HR, 25 PgC yr−1 for SR, 1.0 PgC for FBC and 0.4 PgC for BBC in 0–30 cm, and 1.2 PgC for FBC and 0.7 PgC for BBC in 0–1 m. Increases in microbial C fluxes and pools were widely found, particularly at high latitudes and in equatorial regions, but we also observed their decreases in some grids. Overall, the area-weighted averages of HR, SR, FBC, and BBC in the top 1 m were significantly correlated with those of soil moisture and soil temperature in the top 1 m. These results suggested that microbial C fluxes and pools were jointly governed by vegetation C input and soil temperature and moisture. Our simulations revealed the spatial and temporal patterns of microbial C fluxes and pools in response to environmental change, laying the foundation for an improved understanding of soil microbial roles in the global terrestrial C cycle.

He, Liyuan↗
NASA NTRS1992

Spectral components of human cardiovascular responses to step changes in Lower Body Negative Pressure (LBNP) before and after 22 hour of 6 deg head down bed rest

Changes in autonomic outflow to peripheral organs during the development of bedrest induced orthostatic intolerance have not been determined. Recent studies have indicated that spectral analysis provides an indirect assessment of these changes. Eight male subjects were studied before and after 22 hours of 6 degree head down bedrest plus Lasix (40 mg. P.P.). Cardiovascular spectra (using an autoregressive technique) were determined for heart rate (HR, ECG), arterial pressure (AP, Finapres), radial artery flow (RF, Hokansen) and respiration rate (RR, BoMed). Spectra were obtained from 2.5 minute segments during control, lower body negative pressure (minus 10, 20, 30, 40, 50 mmHg) and recovery. Bedrest increased HR spectra power in the low frequency (.001 to .041 Hz) range, increased RF power in the low and mid (.04 to .18 Hz) range and increased AP power in the high (.18 to .50 Hz) frequency range. Increasing levels of lower body negative pressure decreased HR power and increased RF power in the high frequency range and decreased AP power in the low frequency range. Since spectral power of HR in the high frequency range has been shown to indicate parasympathetically mediated regulation and power in the low and mid frequency ranges indicates a sympathetic / parasympathetic mixture, then both bedrest and lower body negative pressure appeared to shift sympathetic / parasympathetic balance toward sympathetic regulation of HR. The interpretation of the spectral content of AP and RF with respect to their autonomic origins remains unclear.

Knapp, C. F.↗
DOE OSTI2020

The effects of different types of mulch on soil properties and tea production and quality

Abstract BACKGROUND Tea is an important economic crop in China. Mulching, a modern agricultural practice, can modify the soil microenvironment and maintain the crop yield. RESULTS To investigate the effect of different mulching modes on tea plant growth, filed experiments were conducted in a Shizipu tea plantation located in Langxi Country (Xuanchen City, Anhui Province, China). Five treatments were carried out in a randomized complete block arrangement: (i) clean tillage (control); (ii) black plastic film; (iii) weed barrier fabric; (iv) rice straw mulch; and (v) intercropping with Vulpia myuros . The effects of different mulch modes on soil temperature, water moisture, soil compactness, root activity, soil enzyme activity and nutrition status on tea yield, quality and economic benefits were compared at the harvest stage. In the present study, compared with other mulch treatments, intercropping with V. myuros significantly reduced the topsoil temperature (to an optimum temperature) and soil compactness, and increased the water holding capacity in the deep soil layer, which contributed to increased tea root activity and respiration. Furthermore, intercropping with V. myuros significantly increased soil enzymes activity, soil organic matter, and the available nitrogen and phosphorus concentrations in the main root zone. Therefore, the stronger tea root activity accelerated nutrition uptake and increased the tea yield and quality‐related components of the tea, thus resulting in a larger average net income. CONCLUSION Intercropping with V. myuros could serve as a profitable agricultural method for tea production. © 2020 Society of Chemical Industry

Xianchen, Zhang↗