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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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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Sequencing and Analysis of the Sex Determination Region of Populus trichocarpa

The ages and sizes of a sex-determination region (SDR) are difficult to determine in non-model species. Due to the lack of recombination and enrichment of repetitive elements in SDRs, the quality of assembly with short sequencing reads is universally low. Unique features present in the SDRs help provide clues about how SDRs are established and how they evolve in the absence of recombination. Several Populus species have been reported with a male heterogametic configuration of sex (XX/XY system) mapped on chromosome 19, but the exact location of the SDR has been inconsistent among species, and thus far, none of these SDRs has been fully assembled in a genomic context. Here we identify the Y-SDR from a Y-linked contig directly from a long-read PacBio assembly of a Populus trichocarpa male individual. We also identified homologous gene sequences in the SDR of P. trichocarpa and the SDR of the W chromosome in Salix purpurea. We show that inverted repeats (IRs) found in the Y-SDR and the W-SDR are lineage-specific. We hypothesize that, although the two IRs are derived from the same orthologous gene within each species, they likely have independent evolutionary histories. Furthermore, the truncated inverted repeats in P. trichocarpa may code for small RNAs that target the homologous gene for RNA-directed DNA methylation. These findings support the hypothesis that diverse sex-determining systems may be achieved through similar evolutionary pathways, thereby providing a possible mechanism to explain the lability of sex-determination systems in plants in general.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Rapid Cis–Trans Coevolution Driven by a Novel Gene Retroposed from a Eukaryotic Conserved CCR4–NOT Component in Drosophila

Young, or newly evolved, genes arise ubiquitously across the tree of life, and they can rapidly acquire novel functions that influence a diverse array of biological processes. Previous work identified a young regulatory duplicate gene in Drosophila, Zeus that unexpectedly diverged rapidly from its parent, Caf40, an extremely conserved component in the CCR4–NOT machinery in post-transcriptional and post-translational regulation of eukaryotic cells, and took on roles in the male reproductive system. This neofunctionalization was accompanied by differential binding of the Zeus protein to loci throughout the Drosophila melanogaster genome. However, the way in which new DNA-binding proteins acquire and coevolve with their targets in the genome is not understood. Here, by comparing Zeus ChIP-Seq data from D. melanogaster and D. simulans to the ancestral Caf40 binding events from D. yakuba, a species that diverged before the duplication event, we found a dynamic pattern in which Zeus binding rapidly coevolved with a previously unknown DNA motif, which we term Caf40 and Zeus-Associated Motif (CAZAM), under the influence of positive selection. Interestingly, while both copies of Zeus acquired targets at male-biased and testis-specific genes, D. melanogaster and D. simulans proteins have specialized binding on different chromosomes, a pattern echoed in the evolution of the associated motif. Using CRISPR-Cas9-mediated gene knockout of Zeus and RNA-Seq, we found that Zeus regulated the expression of 661 differentially expressed genes (DEGs). Our results suggest that the evolution of young regulatory genes can be coupled to substantial rewiring of the transcriptional networks into which they integrate, even over short evolutionary timescales. Our results thus uncover dynamic genome-wide evolutionary processes associated with new genes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Interpreting Morphological Adaptations Associated with Viviparity in the Tsetse Fly Glossina morsitans (Westwood) by Three-Dimensional Analysis

Tsetse flies (genus Glossina), the sole vectors of African trypanosomiasis, are distinct from most other insects, due to dramatic morphological and physiological adaptations required to support their unique biology. These adaptations are driven by demands associated with obligate hematophagy and viviparous reproduction. Obligate viviparity entails intrauterine larval development and the provision of maternal nutrients for the developing larvae. The reduced reproductive capacity/rate associated with this biology results in increased inter- and intra-sexual competition. Here, we use phase contrast microcomputed tomography (pcMicroCT) to analyze morphological adaptations associated with viviparous biology. These include (1) modifications facilitating abdominal distention required during blood feeding and pregnancy, (2) abdominal and uterine musculature adaptations for gestation and parturition of developed larvae, (3) reduced ovarian structure and capacity, (4) structural features of the male-derived spermatophore optimizing semen/sperm delivery and inhibition of insemination by competing males and (5) structural features of the milk gland facilitating nutrient incorporation and transfer into the uterus. Three-dimensional analysis of these features provides unprecedented opportunities for examination and discovery of internal morphological features not possible with traditional microscopy techniques and provides new opportunities for comparative morphological analyses over time and between species.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Effects of Perfluorinated Alkyl Substances (PFAS) on Amphibian Body and Liver Conditions: Is Lipid Metabolism Being Perturbed throughout Metamorphosis?

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = −0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa.

Bushong, Anna (ORCID:0000000249630578)↗
DOE OSTI2020

MicroRNAs as disease progression biomarkers and therapeutic targets in experimental autoimmune encephalomyelitis model of multiple sclerosis

Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain, spinal cord and optic nerve leading to demyelination. Focal demyelination is associated with relapsing-remitting multiple sclerosis, while progressive forms of the disease show axonal degeneration and neuronal loss. The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity. MicroRNAs (miRNAs) are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases. A review of recent studies with the experimental autoimmune encephalomyelitis animal model (mostly female mice 6–12 weeks of age) has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset (asymptomatic) stage when assessed in blood plasma and urine exosomes, and spinal cord tissue. The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes, brain and spinal cord tissue, and at the post-peak (chronic) stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue. Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease. Interestingly, experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a, miR-23b, miR-497, miR-26a, and miR-20b, or by suppression of miR-182, miR-181c, miR-223, miR-155, and miR873. Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course. Additionally, studies should be performed with male mice of a similar age, and with aged male and female mice.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Sex Differences in the Expression of Drug-Metabolizing and Transporter Genes in Human Liver

Human sex differences in the gene expression of drug metabolizing enzymes and transporters (DMETs) introduce differences in drug absorption, distribution, metabolism and excretion, possibly affecting drug efficacy and adverse reactions. However, existing studies aimed at identifying dimorphic expression differences of DMET genes are limited by sample size and the number of genes profiled. Focusing on a list of 374 DMET genes, we analyzed a previously published gene expression data set consisting of human male (n=234) and female (n=193) liver samples, and identified 77 genes showing differential expression due to sex. To delineate the biological functionalities and regulatory mechanisms for the differentially expressed DMET genes, we conducted a co-expression network analysis. Moreover, clinical implications of sex differences in the expression of human hepatic DMETs are discussed. This study may contribute to the realization of personalized medicine by better understanding the inter-individual differences between males and females in drug/xenobiotic responses and human disease susceptibilities.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Embracing Uncertainty and Perseverance. A Brief Perspective on Conducting On-Site NDT Research

Dr. Judi E. See, a Systems Analyst and Human Factors Engineer at Sandia National Laboratories, reflects on her experience conducting NDT research in a male-dominated environment. She emphasizes the importance of persistence, flexibility, and persuasive skills in overcoming challenges, ranging from gaining access to test sites and equipment to building trust with inspectors. She shares her personal experience of navigating professional situations where gender disparities were evident, highlighting the need for women to adapt and overcome obstacles in traditionally male-dominated settings. See's journey demonstrates that perseverance and ingenuity can lead to significant contributions, process improvements, and recognition in the NDT field.

42 ENGINEERING↗
DOE OSTI2024

Chemical clocks: using otolith geochemistry to enhance estimation of age and growth of white hake (Urophycis tenuis)

The white hake (Urophycis tenuis) is a groundfish distributed throughout the Gulf of Maine. Catch advice is based on stock assessments done with age-based population dynamics models; however, otolith aging is challenging because of unclear growth increments. To address this concern, we compared the consistency of aging with counts of visual annuli to that of aging with cycles of elemental concentrations measured by using laser ablation inductively coupled plasma mass spectrometry. We tested the hypothesis that oscillations in both environmental conditions and internal physiology through time influence uptake of elements during otolith mineralization. Concentrations of manganese, in comparison with those of the other investigated trace elements (magnesium, strontium, and barium), had the most promising correlation with visual growth increments (~100% age agreement, ±1 year), offering an additional tool to enhance increment identification. In our examination of 550 otoliths collected during 2007–2021, we found that white hake lived a maximum of 10.3 years and exhibited sexual dimorphism in maximum length and age. By using generated von Bertalanffy growth functions, L(t)=110(1–e–0.113(t+0.45)) for males and L(t)=140(1–e–0.113(t–0.30)) for females (where L(t) is length at time t), size and age at maturity were calculated for males (37.4 cm in total length (TL), 3.3 years) and females (47.4 cm TL, 4.2 years). These results demonstrate that otolith geochemistry can be used to improve the accuracy and precision of the estimation of fish age and maturity, even for challenging species.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1973

Development testing of a shuttle urine collection system

Flight tests conducted in December 1973 demonstrated the ability of an unisexual urine collection subsystem to function in a zero-g environment. The urinal, which could be adjusted with three degrees of freedom, accommodated 16 female test subjects with a wide range of stature, as well as five male test subjects. The urinal was in intimate contact with the female and was contoured to form an effective air seal at the periphery. When positioned 2-4 inches forward, the urinal could be used for male collection and contact was not required.

Source record↗
NASA NTRS1974

Molding apparatus

Apparatus for compression molding of thermosetting plastics compositions including interfitting hollow male and female components is reported. The components are adapted to be compressed to form a rocket nozzle in a cavity. A thermal jacket is provided exteriorly adjacent to the female component for circulating a thermal transfer fluid to effect curing of a thermosetting plastics material being molded. Each of the male and female components is provided with suitable inlets and outlets for circulating a thermal transfer fluid.

Heier, W. C.↗
NASA NTRS1975

Effects of long-term rotation and hypergravity on developing rat femurs

Male and female Sprague-Dawley rats derived from a single mating were raised for three generations under constant centrifugation at 1.03 G (Rotation Controls) and at 2 G. When the third generation rats were 3 months old, they were sacrificed, and their femurs removed. After fixation and cleaning, the femurs were then measured for length and diameter. Then right femurs were sectioned longitudinally, left femurs transversely. After staining with Hematoxylin and Eosin, right femurs were examined for ossification patterns and left femurs were measured for cortical thickness. All rotation control rats showed marked stimulation of ossification in the femoral head, and males showed significant cortical thinning when compared to non-rotated earth gravity controls. All 2 G femurs showed decreased length and aspect (L/D) ratios, and increased cortical thickness/diameter ratios when compared to earth controls or rotation controls. Ossification of the femoral head was slightly advanced, while the distal epiphyseal plate was thinned.

Smith, S. D.↗
NASA NTRS1976

Subjective response to combined noise and vibration during flight of a large twin-jet airplane

A NASA twin-jet airplane was used to obtain controlled noise and vibration environments during flight while obtaining subjective responses from 13 passenger-subjects (6 females and 7 males). Subjective ratings of overall comfort, comfort when considering only vibration, and comfort when considering only noise were obtained during times of different vibration and noise environments. Passenger-subjects were able to distinguish and rate noise better than vibration. In addition, there was a statistically significant difference in ratings of ride comfort due to both sex type and flight experience. Males rated flying discomfort much more severely than females when rating the overall ride and the ride when considering only the noise environment. Experienced passengers also rated the overall ride to be more uncomfortable than inexperienced passengers.

Clevenson, S. A.↗
NASA NTRS1977

Femoral development in chronically centrifuged rats

Groups of 30-d-old male and female rats were centrifuged at 2.00 G (RE, Rotation Experimental), 1.05 G (RC, Rotation Control) or exposed to the noise and wind of the centrifuge at 1.00 G (EC, Earth Control) for periods of 1, 2, 4, 8, and 16 weeks. Measurements of their femurs indicated that exposure to centrifugation a) decreased femoral length in RE animals, b) increased femoral length in RC animals, c) reduced femoral diameter in RE and RC animals, d) increased L/D ratios in RC animals, e) decreased L/D ratios in RE animals, f) increased femur length/body weight in RE animals, g) decreased cortical thickness (CT) in RE animals, h) increased relative CT in RE animals, and decreased it in RC animals, i) accelerated ossification in RC femoral heads, j) thinned and distorted RE epiphyseal plates, and k) thickened condylar cartilage in RE females. The effects tended to be strongly sexually dimorphic, with females more severely affected by the stress than males.

Smith, S. D.↗
NASA NTRS1977

The effect of increased gravitational stress on bone

A group of 34 adult male chickens were chronically accelerated over an 18-week period; for the last 4 weeks the surviving animals were subjected to a 3-g field. Males of a similar weight and age were used as static controls. The objective was to evaluate the effects of an altered gravitational state on the physical properties of the tibia bone tested for torsional fracture. Of the 34 initial animals, 15 survived for the entire period and were subjected to analysis. The results suggest that the altered morphology produced by increased gravitational fields does not materially affect bone strength, at least in torsion. Decreased bone diameters were accompanied by increased cortical thickness without change in the bone resistance to torsion. The findings of increased cortical thickness with decreased bone diameter suggest reversal of the usual cellular dynamics of adult bone. Data on bone ash and density failed to reveal any substantial changes in bone mineral or organic content. Histological examination of the cortical bone did not disclose any evidence of pathology.

Riggins, R. S.↗
NASA NTRS1978

Physiological responses of women to simulated weightlessness: A review of the first female bed-rest study

Subjects were exposed to centrifugation, to lower body negative pressure (LBNP), and to exericse stress both before and after bed rest. Areas studied were centrifugation tolerance, fluid electrolyte changes and hematology, tolerance to LBNP, physical working capacity, biochemistries, blood fibrinolytic activity, female metabolic and hormonal responses, circadian alterations, and gynecology. Results were compared with the responses observed in similarly bed-rested male subjects. The bed-rested females showed deconditioning responses similar to those of the males, although with some differences. Results indicate that women are capable of coping with exposure to weightlessness and, moreover, that they may be more sensitive subjects for evaluating countermeasures to weightlessness and developing criteria for assessing applicants for shuttle voyages.

Sandler, H.↗
NASA NTRS1978

Microflora analysis of a child with severe combined immune deficiency

The paper presents a microflora analysis of a 5-year-old male child with severe combined immune deficiency who was delivered by Caesarean section and continuously maintained in an isolator. Despite precautions, it was found that the child had come in contact with at least 54 different microbial contaminants. While his skin autoflora was similar to that of a reference group of healthy male adults in numbers of different species and the number of viable cells present per square centimeter of surface area, the subject's autoflora differed from the reference group in that significantly fewer anaerobic species were recovered from the patient's mouth and feces. It is suggested that the child's remaining disease free shows that the reported bacteria are noninvasive or that the unaffected components of the child's immune defense mechanisms are important.

Taylor, G. R.↗
NASA NTRS1980

Change in energy expenditure and brain and adrenal content of catecholamines in rats during muscular loading and hypokinesia

In male 1-7 month old rats, the growth and the protein content of skeletal muscles were higher than in female rats while the O2 consumption and the heart rate were lower. This is combined with reduction of the thyroid gland weight and of catecholamine content in adrenals at the age of 7 months. The development of male and female rats (1-7 month) under conditions of systematic muscular loads increases the growth tempo and protein of skeletal muscles and intensifies the degree of reduction of energy expenditure and the heart rate. This is accomplished by the greater reduction of relative weight of the thyroid gland and, at the age of 7 months, by reduction of the noradrenaline content in the brainstem. Hypodynamic conditions have the exact opposite effect.

Rozanova, V. D.↗
NASA NTRS1981

US plant and radiation dosimetry experiments flown on the Soviet satellite Cosmos 1129

Experiments included: 30 young male Wistar SPF rats used for wide range physiological studies; experiments with plants, fungi, insects, and mammalian tissue cultures; radiation physics experiments; a heat convection study; a rat embryology experiment in which an attempt was made to breed 2 male and 5 female rats during the flight; and fertile quail eggs used to determine the effects of spaceflight on avian embryogenesis. Specimens for US experiments were initially prepared at the recovery site or in Moscow and transferred to US laboratories for complete analyses. An overview of the mission focusing on preflight, on orbit, and postflight activities pertinent to the fourteen US experiments aboard Cosmos 1129 is presented.

Heinrich, M. R.↗