Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “mitochondria”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

A molecular timescale of eukaryote evolution and the rise of complex multicellular life

BACKGROUND: The pattern and timing of the rise in complex multicellular life during Earth's history has not been established. Great disparity persists between the pattern suggested by the fossil record and that estimated by molecular clocks, especially for plants, animals, fungi, and the deepest branches of the eukaryote tree. Here, we used all available protein sequence data and molecular clock methods to place constraints on the increase in complexity through time. RESULTS: Our phylogenetic analyses revealed that (i) animals are more closely related to fungi than to plants, (ii) red algae are closer to plants than to animals or fungi, (iii) choanoflagellates are closer to animals than to fungi or plants, (iv) diplomonads, euglenozoans, and alveolates each are basal to plants+animals+fungi, and (v) diplomonads are basal to other eukaryotes (including alveolates and euglenozoans). Divergence times were estimated from global and local clock methods using 20-188 proteins per node, with data treated separately (multigene) and concatenated (supergene). Different time estimation methods yielded similar results (within 5%): vertebrate-arthropod (964 million years ago, Ma), Cnidaria-Bilateria (1,298 Ma), Porifera-Eumetozoa (1,351 Ma), Pyrenomycetes-Plectomycetes (551 Ma), Candida-Saccharomyces (723 Ma), Hemiascomycetes-filamentous Ascomycota (982 Ma), Basidiomycota-Ascomycota (968 Ma), Mucorales-Basidiomycota (947 Ma), Fungi-Animalia (1,513 Ma), mosses-vascular plants (707 Ma), Chlorophyta-Tracheophyta (968 Ma), Rhodophyta-Chlorophyta+Embryophyta (1,428 Ma), Plantae-Animalia (1,609 Ma), Alveolata-plants+animals+fungi (1,973 Ma), Euglenozoa-plants+animals+fungi (1,961 Ma), and Giardia-plants+animals+fungi (2,309 Ma). By extrapolation, mitochondria arose approximately 2300-1800 Ma and plastids arose 1600-1500 Ma. Estimates of the maximum number of cell types of common ancestors, combined with divergence times, showed an increase from two cell types at 2500 Ma to approximately 10 types at 1500 Ma and 50 cell types at approximately 1000 Ma. CONCLUSIONS: The results suggest that oxygen levels in the environment, and the ability of eukaryotes to extract energy from oxygen, as well as produce oxygen, were key factors in the rise of complex multicellular life. Mitochondria and organisms with more than 2-3 cell types appeared soon after the initial increase in oxygen levels at 2300 Ma. The addition of plastids at 1500 Ma, allowing eukaryotes to produce oxygen, preceded the major rise in complexity.

Evolution, Molecular↗
NASA NTRS2000

Bioenergetics and mitochondrial transmembrane potential during differentiation of cultured osteoblasts

To evaluate the relationship between osteoblast differentiation and bioenergetics, cultured primary osteoblasts from fetal rat calvaria were grown in medium supplemented with ascorbate to induce differentiation. Before ascorbate treatment, the rate of glucose consumption was 320 nmol. h(-1). 10(6) cells(-1), respiration was 40 nmol. h(-1). 10(6) cells(-1), and the ratio of lactate production to glucose consumption was approximately 2, indicating that glycolysis was the main energy source for immature osteoblasts. Ascorbate treatment for 14 days led to a fourfold increase in respiration, a threefold increase in ATP production, and a fivefold increase in ATP content compared with that shown in immature cells. Confocal imaging of mitochondria stained with a transmembrane potential-sensitive vital dye showed that mature cells possessed abundant amounts of high-transmembrane-potential mitochondria, which were concentrated near the culture medium-facing surface. Acute treatment of mature osteoblasts with metabolic inhibitors showed that the rate of glycolysis rose to maintain the cellular energy supply constant. Thus progressive differentiation coincided with changes in cellular metabolism and mitochondrial activity, which are likely to play key roles in osteoblast function.

NASA Center ARC↗
NASA NTRS1984

The origin of the eukaryotic cell

The endosymbiotic hypothesis for the origin of the eukaryotic cell has been applied to the origin of the mitochondria and chloroplasts. However as has been pointed out by Mereschowsky in 1905, it should also be applied to the nucleus as well. If the nucleus, mitochondria and chloroplasts are endosymbionts, then it is likely that the organism that did the engulfing was not a DNA-based organism. In fact, it is useful to postulate that this organism was a primitive RNA-based organism. This hypothesis would explain the preponderance of RNA viruses found in eukaryotic cells. The centriole and basal body do not have a double membrane or DNA. Like all MTOCs (microtubule organising centres), they have a structural or morphic RNA implicated in their formation. This would argue for their origin in the early RNA-based organism rather than in an endosymbiotic event involving bacteria. Finally, the eukaryotic cell uses RNA in ways quite unlike bacteria, thus pointing to a greater emphasis of RNA in both control and structure in the cell. The origin of the eukaryotic cell may tell us why it rather than its prokaryotic relative evolved into the metazoans who are reading this paper.

Review↗
NASA NTRS2000

Androgen and taxol cause cell type-specific alterations of centrosome and DNA organization in androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cells

We investigated the effects of androgen and taxol on the androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cell lines. Cells were treated for 48 and 72 h with 0.05-1 nM of the synthetic androgen R1881 and with 100 nM taxol. Treatment of LNCaP cells with 0.05 nM R1881 led to increased cell proliferation, whereas treatment with 1 nM R1881 resulted in inhibited cell division, DNA cycle arrest, and altered centrosome organization. After treatment with 1 nM R1881, chromatin became clustered, nuclear envelopes convoluted, and mitochondria accumulated around the nucleus. Immunofluorescence microscopy with antibodies to centrosomes showed altered centrosome structure. Although centrosomes were closely associated with the nucleus in untreated cells, they dispersed into the cytoplasm after treatment with 1 nM R1881. Microtubules were only faintly detected in 1 nM R1881-treated LNCaP cells. The effects of taxol included microtubule bundling and altered mitochondria morphology, but not DNA organization. As expected, the androgen-independent prostate cancer cell line DU145 was not affected by R1881. Treatment with taxol resulted in bundling of microtubules in both cell lines. Additional taxol effects were seen in DU145 cells with micronucleation of DNA, an indication of apoptosis. Simultaneous treatment with R1881 and taxol had no additional effects on LNCaP or DU145 cells. These results suggest that LNCaP and DU145 prostate cancer cells show differences not only in androgen responsiveness but in sensitivity to taxol as well. Copyright 2000 Wiley-Liss, Inc.

NASA Program Fundamental Space Biology↗
NASA NTRS2018

Effects of Mitochondrial-Targeted Human Catalase in Skeletal Tissue of Mice Exposed to Simulated Spaceflight

During prolonged spaceflight, astronauts are exposed to both microgravity and space radiation and are at risk forincreased skeletal fragility due to bone loss, Evidence from rodent experiments has established that bothmicrogravity and ionizing radiation can cause bone loss due to increasd of bone-resorbing osteoclasts and decreasedin bone-forming osteoblasts, although the underlying molecular mechanisms for these changes are not fullyunderstood. We hypothesized that excess reactive oxidative species (ROS) produced by conditions that simulatedspaceflight alters the tight balance between osteoclast and osteoblast activities, leading to accelerated skeletalremodeling and culminating in loss of mineralized tissue. To begin to explore this hypothesis, we used the mCATmouse model [1]; these transgenic mice over-express the human catalase gene targeted to mitochondria, which arethe major organelle responsible for cellular production of free radicals. Catalase is an anti-oxidant that catalyzes theconversion of the reactive species, hydrogen peroxide (H202), into water and oxygen. This animal model wasselected as it displays extended lifespan, reduced cardiovascular disease and reduced central nervous systemradiosensitivity, consistent with elevated anti-oxidant activity conferred by the transgene. We reasoned that miceoverexpressing catalase the mitochondria of osteoblast and osteoclast lineage cells would be protected from the boneloss caused by simulated spaceflight.

CATALASE IN SKELETAL TISSUE↗
NASA NTRS2019

Systemic Alterations with Spaceflight Associated Health Risks Originating from Both Circulating miRNAs and Mitochondrial Biology

The many known health risks currently associated with space travel include increased risk of cardiovascular disease, cancer, central nervous system related diseases, muscle degeneration, and changes with host-gut microbiome interactions that can have profound impact with these and other health risks. The majority of the risk from space travel stem of the two components of the space environment which are microgravity and radiation. Two specific systemic effects have been uncovered by us to impact the body as a whole due to the space environment. One factor is related from our earlier work (Beheshti et al, PLOS One, 2018), we predicted that there is a systemic component of the host that causes general increased health risks due to spaceflight driven by a circulating microRNA (miRNA) signature consisting of 13 miRNAs that directly regulates both p53 and TGF1. MiRNAs are small non-coding RNA molecules with a negative and post-transcriptional regulation on gene expression) are increasingly recognized as major systemic regulators of responses to stressors, including microgravity, oxidative stress, and DNA damage. In addition, due to the size and stability of miRNAs, it is known that miRNAs can circulate throughout the body and have been found in the majority of the bodily fluids including blood, urine, saliva, and tears. Here, we start to dissect the actual impact of this miRNA signature on both the radiation and microgravity components and prove that this miRNA signature actually exists in the circulation of a host. The other systemic factor we uncovered was the impact the mitochondria on the whole body due to spaceflight. We hypothesize that spaceflight may promote a physiologic response driven by systemic mitochondria pathways leading to metabolic disorder stemming from the liver and directly impacting other organs and tissues. A systems biology method was implemented utilizing GeneLab datasets that involved in vitro experiments performed at the low Earth orbit, in vivo experiments involving mice flown to space, and finally human physiological data from astronauts. A comprehensive multi-omics approach was implemented which involved correlating transcriptomic analysis with proteomics, metabolomics, and methylation analysis. This approach led us to confirm our hypothesis that a systemic mitochondrial driven response is responsible for increasing potential health risk and is conserved from the in vitro studies, to the in vivo studies, and finally confirmed in astronauts.

Radiation↗
NASA NTRSDate not supplied

Transcriptomic Analysis of ISS Crewmembers’ Peripheral Blood Mononuclear Cells Reveals Homeostatic Regulations in Space

The impact of spaceflight on the immune system has been investigated for decades. Studies conducted in cell models, animals and humans suggest that the spaceflight environment affects the innate and acquired immune systems, as the ability to recognize antigens, defend against foreign invaders, and orchestrate repair is significantly hindered. However, the molecular mechanisms behind spaceflight-induced immune dysregulations are still unclear. In this study, blood from eleven (11) International Space Station (ISS) crewmembers was collected before, during and after long duration space missions, as well as from 11 matched ground control subjects. Transcriptomic analysis was performed in isolated peripheral blood mononuclear cells (PBMCs) using the RNA-sequencing technique. In comparison to the blood samples collected from the crewmembers pre-flight, a total of ~1000 genes were found to be upregulated and ~1000 genes downregulated in PBMC collected between 4 and 6 months after they were in space. The most significantly DEGs (differentially expressed genes) include activation of RUBCNL which is an autophagy enhancer and inhibition of GRASP which regulates cell trafficking. Genes involved in cell adhesion, cell cycle progression and other functions were also dysregulated. Pathway analysis of the DEGs indicates mitochondria dysfunction, particularly reduced ATP production in the electron transport chain. Other pathways impacted by spaceflight include glycolysis, autophagy and inflammatory response. Our results suggest that, in space, blood cells may have also experienced energy depletion and reduced metabolism. Consequently, the cells may become autophagic, which is a known homeostatic mechanism for blood cells to become quiescent, but to stay alive. Further analysis of the data shows recovery of the crewmembers after mission and potential differential responses between genders to the space environment. Our data potentially explains some of the physiological changes that have been observed in space such as mitochondria dysfunction, inhibition of T cell activation and telomere lengthening. Comparison of our results with other transcriptomics studies of ISS crewmembers’ blood cells will also be presented.

Maria Moreno Villanueva↗
DOE OSTI2020

Mitochondrial apoptotic sensor

Mitochondria are central to the intrinsic apoptotic pathway of programmed cell death. Commitment to cell death occurs upon mitochondrial outer membrane permeabilization, and dysregulation of this vital apoptotic control point is implicated in various pathologies. Provided herein are novel sensors which can detect, in real time and with great sensitivity, the release of protons from intact mitochondria caused by mitochondrial outer membrane permeabilization. Embodiments include graphene based ion-sensitive field effect transistors.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Identification of protein/mRNA network involving the PSORS1 locus gene CCHCR1 and the PSORS4 locus gene HAX1

Highlights: • CCHCR1 and HAX1 proteins directly interact. • CCHCR1 is a psoriasis candidate gene located on PSORS1 locus. • HAX1 gene is located on PSORS4 locus and is overexpressed in psoriasis. • CCHCR1 and HAX1 co-localize with and affect specific mRNAs in vesicles. • Novel protein/mRNA networks involving CCHCR1 and HAX1 could play a role in psoriasis. CCHCR1 (Coiled-Coil alpha-Helical Rod 1), maps to chromosomal region 6p21.3, within the major psoriasis susceptibility locus PSORS1. CCHCR1 itself is a plausible psoriasis candidate gene, however its role in psoriasis pathogenesis remains unclear. We previously demonstrated that CCHCR1 protein acts as a cytoplasmic docking site for RNA polymerase II core subunit 3 (RPB3) in cycling cells, suggesting a role for CCHCR1 in vesicular trafficking between cellular compartments. Here, we report a novel interaction between CCHCR1 and the RNA binding protein HAX1. HAX1 maps to chromosomal region 1q21.3 within the PSORS4 locus and is over-expressed in psoriasis. Both CCHCR1 and HAX1 share subcellular co-localization with mitochondria, nuclei and cytoplasmic vesicles as P-bodies. By a series of ribonucleoprotein immunoprecipitation (RIP) assays, we isolated a pool of mRNAs complexed with HAX1 and/or CCHCR1 proteins. Among the mRNAs complexed with both CCHCR1 and HAX1 proteins, there are Vimentin mRNA, previously described to be bound by HAX1, and CAMP/LL37 mRNA, whose gene product is over-expressed in psoriasis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Cellular metabolic stress responses via organelles

Metabolite fluctuations following nutrient metabolism or environmental stresses impact various intracellular signaling networks and stress responses to maintain cellular and organismal homeostasis. It has been shown that subcellular organelles, such as the endoplasmic reticulum, the Golgi apparatus, lysosomes and mitochondria serve as crucial hubs linking alterations in metabolite levels to cellular responses. This role is coordinated by molecular machineries that are associated with the lipid membranes of organelles, which sense the fluctuations in specific metabolites and activate the appropriate signaling and effector molecules. Moreover, recent studies have demonstrated that membraneless organelles, such as the nucleolus and stress granules, are involved in the metabolic stress response. Metabolite-induced post-translational modifications appear to play an important role in this process. Here, we review the molecular mechanisms of metabolite sensing and metabolite-mediated stress responses through membrane-bound and membraneless organelles in mammalian cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Mitoferrin 2 deficiency prevents mitochondrial iron overload-induced endothelial injury and alleviates atherosclerosis

Endothelial dysfunction is an early step in the development of atherosclerotic cardiovascular disease. Iron overload can lead to excessive mitochondrial reactive oxygen species (mtROS) production, resulting in mitochondrial dysfunction and vascular endothelial cell (EC) damage. Mitoferrin 2 (Mfrn2) is an iron transporter in the inner mitochondrial membrane. This study aimed to assess whether Mfrn2 and mitochondrial iron overload were involved in atherosclerosis progression and to explore the potential mechanism. We observed significant upregulation of Mfrn2 in the arteries of high-fat diet (HFD)-fed Apolipoprotein E{sup −/-} (ApoE{sup −/-}) mice and in TNF-α-induced mouse aortic endothelial cells (MAECs). Mfrn2 gene silencing inhibited mitochondrial iron overload, stabilized mitochondrial membrane potential and improved mitochondrial function in TNF-α-induced MAECs. Vascular EC-specific knockdown of Mfrn2 in ApoE{sup −/-} mice markedly decreased atherosclerotic lesion formation and the levels of ICAM-1 in aortas and reduced monocyte infiltration into the vascular wall. Furthermore, TNF-α increased the binding of 14-3-3 epsilon (ε) and Mfrn2, preventing Mfrn2 degradation and leading to mitochondrial iron overload in ECs, while 14-3-3ε overexpression increased Mfrn2 stability by inhibiting its ubiquitination. Together, our results reveal that Mfrn2 deficiency attenuates endothelial dysfunction by decreasing iron levels within the mitochondria and mitochondrial dysfunction. These findings may provide new insights into preventive and therapeutic strategies against vascular endothelial dysfunction in atherosclerotic disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Drosophila models to study causative genes for human rare intractable neurological diseases

Highlights: • Drosophila models targeting some ALS-causing genes are described. • Drosophila models targeting some CMT-causing genes are described. • Drosophila models targeting some Sotos syndrome-causing genes are described. • Genes and pathways that commonly interact with ALS- and/or CMT-causing genes are described. Drosophila is emerging as a convenient model for investigating human diseases. Functional homologues of almost 75% of human disease-related genes are found in Drosophila. Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease that causes defects in motoneurons. Charcot-Marie-Tooth disease (CMT) is one of the most commonly found inherited neuropathies affecting both motor and sensory neurons. No effective therapy has been established for either of these diseases. In this review, after overviewing ALS, Drosophila models targeting several ALS-causing genes, including TDP-43, FUS and Ubiquilin2, are described with their genetic interactants. Then, after overviewing CMT, examples of Drosophila models targeting several CMT-causing genes, including mitochondria-related genes and FIG 4, are also described with their genetic interactants. In addition, we introduce Sotos syndrome caused by mutations in the epigenetic regulator gene NSD1. Lastly, several genes and pathways that commonly interact with ALS- and/or CMT-causing genes are described. In the case of ALS and CMT that have many causative genes, it may be not practical to perform gene therapy for each of the many disease-causing genes. The possible uses of the common genes and pathways as novel diagnosis markers and effective therapeutic targets are discussed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Caffeic acid attenuates irradiation-induced hematopoietic stem cell apoptosis through inhibiting mitochondrial damage

Highlights: • IR-induced mitochondrial damage accelerates HSC apoptosis. • CA attenuates mitochondrial damage and apoptosis of HSCs induced by IR. • CA protects against BM hematopoietic failure in mice after IR exposure. Hematopoietic stem cells (HSCs) are sensitive to ionizing radiation (IR) damage, and its injury is the primary cause of bone marrow (BM) hematopoietic failure and even death after exposure to a certain dose of IR. However, the underlying mechanisms remain incompletely understood. Here we show that mitochondrial oxidative damage, which is characterized by mitochondrial reactive oxygen species overproduction, mitochondrial membrane potential reduction and mitochondrial permeability transition pore opening, is rapidly induced in both human and mouse HSCs and directly accelerates HSC apoptosis after IR exposure. Mechanistically, 5-lipoxygenase (5-LOX) is induced by IR exposure and contributes to IR-induced mitochondrial oxidative damage through inducing lipid peroxidation. Intriguingly, a natural antioxidant, caffeic acid (CA), can attenuate IR-induced HSC apoptosis through suppressing 5-LOX-mediated mitochondrial oxidative damage, thus protecting against BM hematopoietic failure after IR exposure. These findings uncover a critical role for mitochondria in IR-induced HSC injury and highlight the therapeutic potential of CA in BM hematopoietic failure induced by IR.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

A universal metabolite repair enzyme removes a strong inhibitor of the TCA cycle

Abstract A prevalent side-reaction of succinate dehydrogenase oxidizes malate to enol-oxaloacetate (OAA), a metabolically inactive form of OAA that is a strong inhibitor of succinate dehydrogenase. We purified from cow heart mitochondria an enzyme (OAT1) with OAA tautomerase (OAT) activity that converts enol-OAA to the physiological keto-OAA form, and determined that it belongs to the highly conserved and previously uncharacterized Fumarylacetoacetate_hydrolase_domain-containing protein family. From all three domains of life, heterologously expressed proteins were shown to have strong OAT activity, and ablating the OAT1 homolog caused significant growth defects. In Escherichia coli , expression of succinate dehydrogenase was necessary for OAT1-associated growth defects to occur, and ablating OAT1 caused a significant increase in acetate and other metabolites associated with anaerobic respiration. OAT1 increased the succinate dehydrogenase reaction rate by 35% in in vitro assays with physiological concentrations of both succinate and malate. Our results suggest that OAT1 is a universal metabolite repair enzyme that is required to maximize aerobic respiration efficiency by preventing succinate dehydrogenase inhibition.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Structural insights into the assembly and the function of the plant oxidative phosphorylation system

One of the key functions of mitochondria is the production of ATP to support cellular metabolism and growth. The last step of mitochondrial ATP synthesis is performed by the oxidative phosphorylation (OXPHOS) system, an ensemble of protein complexes embedded in the inner mitochondrial membrane. In the last 25 yr, many structures of OXPHOS complexes and supercomplexes have been resolved in yeast, mammals, and bacteria. However, structures of plant OXPHOS enzymes only became available very recently. In this review, we highlight the plant-specific features revealed by the recent structures and discuss how they advance our understanding of the function and assembly of plant OXPHOS complexes. Here we also propose new hypotheses to be tested and discuss older findings to be re-evaluated. Further biochemical and structural work on the plant OXPHOS system will lead to a deeper understanding of plant respiration and its regulation, with significant agricultural, environmental, and societal implications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Markers of mitochondrial function and oxidative metabolism in skeletal muscle do not display intrinsic circadian regulation in female mice

Mitochondria are key regulators of metabolism and ATP supply in skeletal muscle, while circadian rhythms influence many physiological processes. However, whether mitochondrial function is intrinsically regulated in a circadian manner in mouse skeletal muscle is inadequately understood. Accordingly, we measured postabsorptive transcript abundance of markers of mitochondrial autophagy, dynamics, and metabolism [extensor digitorum longus (EDL), soleus, gastrocnemius], protein abundance of electron transport chain complexes (EDL and soleus), enzymatic activity of succinate dehydrogenase (tibialis anterior and plantaris), and maximal mitochondrial respiration (tibialis anterior) in different skeletal muscles from female C57BL/6NJ mice at four zeitgeber times: 1, 7, 13, and 19. Our findings demonstrate that markers of mitochondrial function and oxidative metabolism do not display intrinsic time-of-day regulation at the gene, protein, enzymatic, or functional level. The core-clock genes Bmal1 and Dbp exhibited intrinsic circadian rhythmicity in skeletal muscle (i.e., EDL, soleus, gastrocnemius) and circadian amplitude varied by muscle type. These findings demonstrate that female mouse skeletal muscle does not display circadian regulation of markers of mitochondrial function or oxidative metabolism over 24 h.

Circadian Biology↗
DOE OSTI2021

Altered Cardiac Energetics and Mitochondrial Dysfunction in Hypertrophic Cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is a complex disease partly explained by the effects of individual gene variants on sarcomeric protein biomechanics. At the cellular level, HCM mutations most commonly enhance force production, leading to higher energy demands. Despite significant advances in elucidating sarcomeric structure–function relationships, there is still much to be learned about the mechanisms that link altered cardiac energetics to HCM phenotypes. Here, we test the hypothesis that changes in cardiac energetics represent a common pathophysiologic pathway in HCM. Methods: We performed a comprehensive multiomics profile of the molecular (transcripts, metabolites, and complex lipids), ultrastructural, and functional components of HCM energetics using myocardial samples from 27 HCM patients and 13 normal controls (donor hearts). Results: Integrated omics analysis revealed alterations in a wide array of biochemical pathways with major dysregulation in fatty acid metabolism, reduction of acylcarnitines, and accumulation of free fatty acids. HCM hearts showed evidence of global energetic decompensation manifested by a decrease in high energy phosphate metabolites (ATP, ADP, and phosphocreatine) and a reduction in mitochondrial genes involved in creatine kinase and ATP synthesis. Accompanying these metabolic derangements, electron microscopy showed an increased fraction of severely damaged mitochondria with reduced cristae density, coinciding with reduced citrate synthase activity and mitochondrial oxidative respiration. These mitochondrial abnormalities were associated with elevated reactive oxygen species and reduced antioxidant defenses. However, despite significant mitochondrial injury, HCM hearts failed to upregulate mitophagic clearance. Conclusions: Overall, our findings suggest that perturbed metabolic signaling and mitochondrial dysfunction are common pathogenic mechanisms in patients with HCM. These results highlight potential new drug targets for attenuation of the clinical disease through improving metabolic function and reducing mitochondrial injury.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

An intensity-based post-processing tool for 3D instance segmentation of organelles in soft X-ray tomograms

Investigating the 3D structures and rearrangements of organelles within a single cell is critical for better characterizing cellular function. Imaging approaches such as soft X-ray tomography have been widely applied to reveal a complex subcellular organization involving multiple inter-organelle interactions. However, 3D segmentation of organelle instances has been challenging despite its importance in organelle characterization. Here we propose an intensity-based post-processing tool to identify and separate organelle instances. Our tool separates sphere-like (insulin vesicle) and columnar-shaped organelle instances (mitochondrion) based on the intensity of raw tomograms, semantic segmentation masks, and organelle morphology. We validate our tool using synthetic tomograms of organelles and experimental tomograms of pancreatic β -cells to separate insulin vesicle and mitochondria instances. As compared to the commonly used connected regions labeling, watershed, and watershed + Gaussian filter methods, our tool results in improved accuracy in identifying organelles in the synthetic tomograms and an improved description of organelle structures in β -cell tomograms. In addition, under different experimental treatment conditions, significant changes in volumes and intensities of both insulin vesicle and mitochondrion are observed in our instance results, revealing their potential roles in maintaining normal β -cell function. Our tool is expected to be applicable for improving the instance segmentation of other images obtained from different cell types using multiple imaging modalities.

59 BASIC BIOLOGICAL SCIENCES↗