1
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Wu TTH, Travaglini KJ, Rustagi A, Xu D, Zhang Y, Andronov L, Jang S, Gillich A, Dehghannasiri R, Martínez-Colón GJ, Beck A, Liu DD, Wilk AJ, Morri M, Trope WL, Bierman R, Weissman IL, Shrager JB, Quake SR, Kuo CS, Salzman J, Moerner W, Kim PS, Blish CA, Krasnow MA. Interstitial macrophages are a focus of viral takeover and inflammation in COVID-19 initiation in human lung. J Exp Med 2024; 221:e20232192. [PMID: 38597954 PMCID: PMC11009983 DOI: 10.1084/jem.20232192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/09/2024] [Accepted: 03/04/2024] [Indexed: 04/11/2024] Open
Abstract
Early stages of deadly respiratory diseases including COVID-19 are challenging to elucidate in humans. Here, we define cellular tropism and transcriptomic effects of SARS-CoV-2 virus by productively infecting healthy human lung tissue and using scRNA-seq to reconstruct the transcriptional program in "infection pseudotime" for individual lung cell types. SARS-CoV-2 predominantly infected activated interstitial macrophages (IMs), which can accumulate thousands of viral RNA molecules, taking over 60% of the cell transcriptome and forming dense viral RNA bodies while inducing host profibrotic (TGFB1, SPP1) and inflammatory (early interferon response, CCL2/7/8/13, CXCL10, and IL6/10) programs and destroying host cell architecture. Infected alveolar macrophages (AMs) showed none of these extreme responses. Spike-dependent viral entry into AMs used ACE2 and Sialoadhesin/CD169, whereas IM entry used DC-SIGN/CD209. These results identify activated IMs as a prominent site of viral takeover, the focus of inflammation and fibrosis, and suggest targeting CD209 to prevent early pathology in COVID-19 pneumonia. This approach can be generalized to any human lung infection and to evaluate therapeutics.
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Affiliation(s)
- Timothy Ting-Hsuan Wu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
| | - Kyle J. Travaglini
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
| | - Arjun Rustagi
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Duo Xu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Sarafan ChEM-H, Stanford University, Stanford, CA, USA
| | - Yue Zhang
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Leonid Andronov
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - SoRi Jang
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
| | - Astrid Gillich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
| | - Roozbeh Dehghannasiri
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, CA, USA
| | - Giovanny J. Martínez-Colón
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Program in Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Aimee Beck
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Daniel Dan Liu
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Aaron J. Wilk
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Program in Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Winston L. Trope
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Rob Bierman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Irving L. Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Joseph B. Shrager
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Stephen R. Quake
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Christin S. Kuo
- Department of Pediatrics, Pulmonary Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Julia Salzman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, CA, USA
| | - W.E. Moerner
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Peter S. Kim
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Sarafan ChEM-H, Stanford University, Stanford, CA, USA
| | - Catherine A. Blish
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Program in Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Mark A. Krasnow
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Vera Moulton Wall Center for Pulmonary Vascular Disease, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, San Francisco, CA, USA
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2
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Yamaya K, Wang B, Memar N, Odiba A, Woglar A, Gartner A, Villeneuve A. Disparate roles for C. elegans DNA translocase paralogs RAD-54.L and RAD-54.B in meiotic prophase germ cells. Nucleic Acids Res 2023; 51:9183-9202. [PMID: 37548405 PMCID: PMC10516670 DOI: 10.1093/nar/gkad638] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/06/2023] [Accepted: 07/20/2023] [Indexed: 08/08/2023] Open
Abstract
RAD54 family DNA translocases partner with RAD51 recombinases to ensure stable genome inheritance, exhibiting biochemical activities both in promoting recombinase removal and in stabilizing recombinase association with DNA. Understanding how such disparate activities of RAD54 paralogs align with their biological roles is an ongoing challenge. Here we investigate the in vivo functions of Caenorhabditis elegans RAD54 paralogs RAD-54.L and RAD-54.B during meiotic prophase, revealing distinct contributions to the dynamics of RAD-51 association with DNA and to the progression of meiotic double-strand break repair (DSBR). While RAD-54.L is essential for RAD-51 removal from meiotic DSBR sites to enable recombination progression, RAD-54.B is largely dispensable for meiotic DSBR. However, RAD-54.B is required to prevent hyperaccumulation of RAD-51 on unbroken DNA during the meiotic sub-stage when DSBs and early recombination intermediates form. Moreover, DSB-independent hyperaccumulation of RAD-51 foci in the absence of RAD-54.B is RAD-54.L-dependent, revealing a hidden activity of RAD-54.L in promoting promiscuous RAD-51 association that is antagonized by RAD-54.B. We propose a model wherein a division of labor among RAD-54 paralogs allows germ cells to ramp up their capacity for efficient homologous recombination that is crucial to successful meiosis while counteracting potentially deleterious effects of unproductive RAD-51 association with unbroken DNA.
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Affiliation(s)
- Kei Yamaya
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Bin Wang
- State Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007 Nanning, China
| | - Nadin Memar
- IBS Center for Genomic Integrity and Department for Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Korea
| | - Arome Solomon Odiba
- State Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007 Nanning, China
| | - Alexander Woglar
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Swiss Institute for Experimental Cancer Research (ISREC) and School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Anton Gartner
- IBS Center for Genomic Integrity and Department for Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Korea
| | - Anne M Villeneuve
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
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3
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Bielczyk-Maczynska E, Sharma D, Blencowe M, Saliba Gustafsson P, Gloudemans MJ, Yang X, Carcamo-Orive I, Wabitsch M, Svensson KJ, Park CY, Quertermous T, Knowles JW, Li J. A single-cell CRISPRi platform for characterizing candidate genes relevant to metabolic disorders in human adipocytes. Am J Physiol Cell Physiol 2023; 325:C648-C660. [PMID: 37486064 PMCID: PMC10635647 DOI: 10.1152/ajpcell.00148.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/07/2023] [Accepted: 07/19/2023] [Indexed: 07/25/2023]
Abstract
CROP-Seq combines gene silencing using CRISPR interference with single-cell RNA sequencing. Here, we applied CROP-Seq to study adipogenesis and adipocyte biology. Human preadipocyte SGBS cell line expressing KRAB-dCas9 was transduced with a sgRNA library. Following selection, individual cells were captured using microfluidics at different timepoints during adipogenesis. Bioinformatic analysis of transcriptomic data was used to determine the knockdown effects, the dysregulated pathways, and to predict cellular phenotypes. Single-cell transcriptomes recapitulated adipogenesis states. For all targets, over 400 differentially expressed genes were identified at least at one timepoint. As a validation of our approach, the knockdown of PPARG and CEBPB (which encode key proadipogenic transcription factors) resulted in the inhibition of adipogenesis. Gene set enrichment analysis generated hypotheses regarding the molecular function of novel genes. MAFF knockdown led to downregulation of transcriptional response to proinflammatory cytokine TNF-α in preadipocytes and to decreased CXCL-16 and IL-6 secretion. TIPARP knockdown resulted in increased expression of adipogenesis markers. In summary, this powerful, hypothesis-free tool can identify novel regulators of adipogenesis, preadipocyte, and adipocyte function associated with metabolic disease.NEW & NOTEWORTHY Genomics efforts led to the identification of many genomic loci that are associated with metabolic traits, many of which are tied to adipose tissue function. However, determination of the causal genes, and their mechanism of action in metabolism, is a time-consuming process. Here, we use an approach to determine the transcriptional outcome of candidate gene knockdown for multiple genes at the same time in a human cell model of adipogenesis.
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Affiliation(s)
- Ewa Bielczyk-Maczynska
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
| | - Disha Sharma
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
| | - Montgomery Blencowe
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California, United States
| | - Peter Saliba Gustafsson
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
- Cardiovascular Medicine Unit, Department of Medicine, Center for Molecular Medicine at BioClinicum, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Michael J Gloudemans
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States
- Biomedical Informatics Training Program, Stanford, California, United States
| | - Xia Yang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California, United States
| | - Ivan Carcamo-Orive
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
| | - Martin Wabitsch
- Department of Pediatrics and Adolescent Medicine, Center for Rare Endocrine Diseases, Division of Pediatric Endocrinology and Diabetes, Ulm University Medical Centre, Ulm, Germany
| | - Katrin J Svensson
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States
| | - Chong Y Park
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
| | - Thomas Quertermous
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
| | - Joshua W Knowles
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
- Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, California, United States
| | - Jiehan Li
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, California, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, United States
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4
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Liu CC, Greenwald NF, Kong A, McCaffrey EF, Leow KX, Mrdjen D, Cannon BJ, Rumberger JL, Varra SR, Angelo M. Robust phenotyping of highly multiplexed tissue imaging data using pixel-level clustering. Nat Commun 2023; 14:4618. [PMID: 37528072 PMCID: PMC10393943 DOI: 10.1038/s41467-023-40068-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/11/2023] [Indexed: 08/03/2023] Open
Abstract
While technologies for multiplexed imaging have provided an unprecedented understanding of tissue composition in health and disease, interpreting this data remains a significant computational challenge. To understand the spatial organization of tissue and how it relates to disease processes, imaging studies typically focus on cell-level phenotypes. However, images can capture biologically important objects that are outside of cells, such as the extracellular matrix. Here, we describe a pipeline, Pixie, that achieves robust and quantitative annotation of pixel-level features using unsupervised clustering and show its application across a variety of biological contexts and multiplexed imaging platforms. Furthermore, current cell phenotyping strategies that rely on unsupervised clustering can be labor intensive and require large amounts of manual cluster adjustments. We demonstrate how pixel clusters that lie within cells can be used to improve cell annotations. We comprehensively evaluate pre-processing steps and parameter choices to optimize clustering performance and quantify the reproducibility of our method. Importantly, Pixie is open source and easily customizable through a user-friendly interface.
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Affiliation(s)
- Candace C Liu
- Department of Pathology, Stanford University, Stanford, CA, USA
| | | | - Alex Kong
- Department of Pathology, Stanford University, Stanford, CA, USA
| | | | - Ke Xuan Leow
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Dunja Mrdjen
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Bryan J Cannon
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Josef Lorenz Rumberger
- Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
- Charité University Medicine, Berlin, Germany
| | | | - Michael Angelo
- Department of Pathology, Stanford University, Stanford, CA, USA.
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5
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Yeo RW, Zhou OY, Zhong BL, Sun ED, Navarro Negredo P, Nair S, Sharmin M, Ruetz TJ, Wilson M, Kundaje A, Dunn AR, Brunet A. Chromatin accessibility dynamics of neurogenic niche cells reveal defects in neural stem cell adhesion and migration during aging. Nat Aging 2023; 3:866-893. [PMID: 37443352 PMCID: PMC10353944 DOI: 10.1038/s43587-023-00449-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 06/02/2023] [Indexed: 07/15/2023]
Abstract
The regenerative potential of brain stem cell niches deteriorates during aging. Yet the mechanisms underlying this decline are largely unknown. Here we characterize genome-wide chromatin accessibility of neurogenic niche cells in vivo during aging. Interestingly, chromatin accessibility at adhesion and migration genes decreases with age in quiescent neural stem cells (NSCs) but increases with age in activated (proliferative) NSCs. Quiescent and activated NSCs exhibit opposing adhesion behaviors during aging: quiescent NSCs become less adhesive, whereas activated NSCs become more adhesive. Old activated NSCs also show decreased migration in vitro and diminished mobilization out of the niche for neurogenesis in vivo. Using tension sensors, we find that aging increases force-producing adhesions in activated NSCs. Inhibiting the cytoskeletal-regulating kinase ROCK reduces these adhesions, restores migration in old activated NSCs in vitro, and boosts neurogenesis in vivo. These results have implications for restoring the migratory potential of NSCs and for improving neurogenesis in the aged brain.
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Affiliation(s)
- Robin W Yeo
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Olivia Y Zhou
- Department of Genetics, Stanford University, Stanford, CA, USA
- Stanford Biophysics Program, Stanford University, Stanford, CA, USA
- Stanford Medical Scientist Training Program, Stanford University, Stanford, CA, USA
| | - Brian L Zhong
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Eric D Sun
- Department of Genetics, Stanford University, Stanford, CA, USA
- Biomedical Informatics Graduate Program, Stanford University, Stanford, CA, USA
| | | | - Surag Nair
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Mahfuza Sharmin
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Tyson J Ruetz
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Mikaela Wilson
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Anshul Kundaje
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA, USA.
- Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA, USA.
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA.
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6
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Chappell CR, Muglia LJ. Fostering science-art collaborations: A toolbox of resources. PLoS Biol 2023; 21:e3001992. [PMID: 36757944 PMCID: PMC9910691 DOI: 10.1371/journal.pbio.3001992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
Scientists and artists are both motivated by creativity and curiosity, and science and art can be mutually reinforcing, supporting discovery and innovation. This Community Page highlights resources for individuals, groups, and institutions to advance science-art collaborations.
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Affiliation(s)
- Callie R. Chappell
- Department of Biology, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Louis J. Muglia
- Burroughs Wellcome Fund, Research Triangle Park, Durham, North Carolina, United States of America
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7
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McKay A, Costa EK, Chen J, Hu CK, Chen X, Bedbrook CN, Khondker RC, Thielvoldt M, Priya Singh P, Wyss-Coray T, Brunet A. An automated feeding system for the African killifish reveals the impact of diet on lifespan and allows scalable assessment of associative learning. eLife 2022; 11:e69008. [PMID: 36354233 PMCID: PMC9788828 DOI: 10.7554/elife.69008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 11/09/2022] [Indexed: 11/11/2022] Open
Abstract
The African turquoise killifish is an exciting new vertebrate model for aging studies. A significant challenge for any model organism is the control over its diet in space and time. To address this challenge, we created an automated and networked fish feeding system. Our automated feeder is designed to be open-source, easily transferable, and built from widely available components. Compared to manual feeding, our automated system is highly precise and flexible. As a proof of concept for the feeding flexibility of these automated feeders, we define a favorable regimen for growth and fertility for the African killifish and a dietary restriction regimen where both feeding time and quantity are reduced. We show that this dietary restriction regimen extends lifespan in males (but not in females) and impacts the transcriptomes of killifish livers in a sex-specific manner. Moreover, combining our automated feeding system with a video camera, we establish a quantitative associative learning assay to provide an integrative measure of cognitive performance for the killifish. The ability to precisely control food delivery in the killifish opens new areas to assess lifespan and cognitive behavior dynamics and to screen for dietary interventions and drugs in a scalable manner previously impossible with traditional vertebrate model organisms.
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Affiliation(s)
- Andrew McKay
- Department of Genetics, Stanford UniversityStanfordUnited States
- Biology Graduate Program, Stanford UniversityStanfordUnited States
| | - Emma K Costa
- Department of Neurology and Neurological Sciences, Stanford UniversityStanfordUnited States
- Neurosciences Interdepartmental Program, Stanford University School of MedicineStanfordUnited States
| | - Jingxun Chen
- Department of Genetics, Stanford UniversityStanfordUnited States
| | - Chi-Kuo Hu
- Department of Genetics, Stanford UniversityStanfordUnited States
| | - Xiaoshan Chen
- Department of Genetics, Stanford UniversityStanfordUnited States
| | - Claire N Bedbrook
- Department of Genetics, Stanford UniversityStanfordUnited States
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | | | | | | | - Tony Wyss-Coray
- Department of Neurology and Neurological Sciences, Stanford UniversityStanfordUnited States
- Glenn Laboratories for the Biology of Aging, Stanford UniversityStanfordUnited States
- Wu Tsai Neurosciences Institute, Stanford UniversityStanfordUnited States
| | - Anne Brunet
- Department of Genetics, Stanford UniversityStanfordUnited States
- Glenn Laboratories for the Biology of Aging, Stanford UniversityStanfordUnited States
- Wu Tsai Neurosciences Institute, Stanford UniversityStanfordUnited States
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8
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Athni TS, Shocket MS, Couper LI, Nova N, Caldwell IR, Caldwell JM, Childress JN, Childs ML, De Leo GA, Kirk DG, MacDonald AJ, Olivarius K, Pickel DG, Roberts SO, Winokur OC, Young HS, Cheng J, Grant EA, Kurzner PM, Kyaw S, Lin BJ, López RC, Massihpour DS, Olsen EC, Roache M, Ruiz A, Schultz EA, Shafat M, Spencer RL, Bharti N, Mordecai EA. The influence of vector-borne disease on human history: socio-ecological mechanisms. Ecol Lett 2021; 24:829-846. [PMID: 33501751 PMCID: PMC7969392 DOI: 10.1111/ele.13675] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 01/14/2023]
Abstract
Vector-borne diseases (VBDs) are embedded within complex socio-ecological systems. While research has traditionally focused on the direct effects of VBDs on human morbidity and mortality, it is increasingly clear that their impacts are much more pervasive. VBDs are dynamically linked to feedbacks between environmental conditions, vector ecology, disease burden, and societal responses that drive transmission. As a result, VBDs have had profound influence on human history. Mechanisms include: (1) killing or debilitating large numbers of people, with demographic and population-level impacts; (2) differentially affecting populations based on prior history of disease exposure, immunity, and resistance; (3) being weaponised to promote or justify hierarchies of power, colonialism, racism, classism and sexism; (4) catalysing changes in ideas, institutions, infrastructure, technologies and social practices in efforts to control disease outbreaks; and (5) changing human relationships with the land and environment. We use historical and archaeological evidence interpreted through an ecological lens to illustrate how VBDs have shaped society and culture, focusing on case studies from four pertinent VBDs: plague, malaria, yellow fever and trypanosomiasis. By comparing across diseases, time periods and geographies, we highlight the enormous scope and variety of mechanisms by which VBDs have influenced human history.
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Affiliation(s)
- Tejas S. Athni
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Marta S. Shocket
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Lisa I. Couper
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Nicole Nova
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Iain R. Caldwell
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Jamie M. Caldwell
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Biology, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Jasmine N. Childress
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Marissa L. Childs
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, CA, USA
| | - Giulio A. De Leo
- Hopkins Marine Station of Stanford University, Pacific Grove, CA, USA
- Woods Institute for the Environment, Stanford University, Stanford, CA, USA
| | - Devin G. Kirk
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Andrew J. MacDonald
- Bren School of Environmental Science and Management, University of California, Santa Barbara, CA, USA
- Earth Research Institute, University of California, Santa Barbara, CA, USA
| | | | - David G. Pickel
- Department of Classics, Stanford University, Stanford, CA, USA
| | | | - Olivia C. Winokur
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Hillary S. Young
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Julian Cheng
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | | | - Saw Kyaw
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Bradford J. Lin
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | | | - Erica C. Olsen
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Maggie Roache
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Angie Ruiz
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Muskan Shafat
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Nita Bharti
- Department of Biology, Center for Infectious Disease Dynamics, Penn State University, University Park, PA, USA
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9
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Brewer SM, Twittenhoff C, Kortmann J, Brubaker SW, Honeycutt J, Massis LM, Pham THM, Narberhaus F, Monack DM. A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature. PLoS Pathog 2021; 17:e1009345. [PMID: 33651854 PMCID: PMC7954313 DOI: 10.1371/journal.ppat.1009345] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 03/12/2021] [Accepted: 01/28/2021] [Indexed: 12/20/2022] Open
Abstract
Sensing and responding to environmental signals is critical for bacterial pathogens to successfully infect and persist within hosts. Many bacterial pathogens sense temperature as an indication they have entered a new host and must alter their virulence factor expression to evade immune detection. Using secondary structure prediction, we identified an RNA thermosensor (RNAT) in the 5' untranslated region (UTR) of tviA encoded by the typhoid fever-causing bacterium Salmonella enterica serovar Typhi (S. Typhi). Importantly, tviA is a transcriptional regulator of the critical virulence factors Vi capsule, flagellin, and type III secretion system-1 expression. By introducing point mutations to alter the mRNA secondary structure, we demonstrate that the 5' UTR of tviA contains a functional RNAT using in vitro expression, structure probing, and ribosome binding methods. Mutational inhibition of the RNAT in S. Typhi causes aberrant virulence factor expression, leading to enhanced innate immune responses during infection. In conclusion, we show that S. Typhi regulates virulence factor expression through an RNAT in the 5' UTR of tviA. Our findings demonstrate that limiting inflammation through RNAT-dependent regulation in response to host body temperature is important for S. Typhi's "stealthy" pathogenesis.
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Affiliation(s)
- Susan M. Brewer
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | | | - Jens Kortmann
- Genentech, Inc., South San Francisco, California, United States of America
| | - Sky W. Brubaker
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jared Honeycutt
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Liliana Moura Massis
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Trung H. M. Pham
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | | | - Denise M. Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
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10
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Kasmalkar IG, Serafin KA, Miao Y, Bick IA, Ortolano L, Ouyang D, Suckale J. When floods hit the road: Resilience to flood-related traffic disruption in the San Francisco Bay Area and beyond. Sci Adv 2020; 6:eaba2423. [PMID: 32821823 PMCID: PMC7406370 DOI: 10.1126/sciadv.aba2423] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
As sea level rises, urban traffic networks in low-lying coastal areas face increasing risks of flood disruptions. Closure of flooded roads causes employee absences and delays, creating cascading impacts to communities. We integrate a traffic model with flood maps that represent potential combinations of storm surges, tides, seasonal cycles, interannual anomalies driven by large-scale climate variability such as the El Niño Southern Oscillation, and sea level rise. When identifying inundated roads, we propose corrections for potential biases arising from model integration. Our results for the San Francisco Bay Area show that employee absences are limited to the homes and workplaces within the areas of inundation, while delays propagate far inland. Communities with limited availability of alternate roads experience long delays irrespective of their proximity to the areas of inundation. We show that metric reach, a measure of road network density, is a better proxy for delays than flood exposure.
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Affiliation(s)
- Indraneel G. Kasmalkar
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Katherine A. Serafin
- Department of Geophysics, Stanford University, Stanford, CA, USA
- Department of Geography, University of Florida, Gainesville, FL, USA
| | - Yufei Miao
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - I. Avery Bick
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - Leonard Ortolano
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - Derek Ouyang
- Department of Geophysics, Stanford University, Stanford, CA, USA
| | - Jenny Suckale
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
- Department of Geophysics, Stanford University, Stanford, CA, USA
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
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11
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Melianas A, Quill TJ, LeCroy G, Tuchman Y, Loo HV, Keene ST, Giovannitti A, Lee HR, Maria IP, McCulloch I, Salleo A. Temperature-resilient solid-state organic artificial synapses for neuromorphic computing. Sci Adv 2020; 6:6/27/eabb2958. [PMID: 32937458 PMCID: PMC7458436 DOI: 10.1126/sciadv.abb2958] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 05/20/2020] [Indexed: 05/18/2023]
Abstract
Devices with tunable resistance are highly sought after for neuromorphic computing. Conventional resistive memories, however, suffer from nonlinear and asymmetric resistance tuning and excessive write noise, degrading artificial neural network (ANN) accelerator performance. Emerging electrochemical random-access memories (ECRAMs) display write linearity, which enables substantially faster ANN training by array programing in parallel. However, state-of-the-art ECRAMs have not yet demonstrated stable and efficient operation at temperatures required for packaged electronic devices (~90°C). Here, we show that (semi)conducting polymers combined with ion gel electrolyte films enable solid-state ECRAMs with stable and nearly temperature-independent operation up to 90°C. These ECRAMs show linear resistance tuning over a >2× dynamic range, 20-nanosecond switching, submicrosecond write-read cycling, low noise, and low-voltage (±1 volt) and low-energy (~80 femtojoules per write) operation combined with excellent endurance (>109 write-read operations at 90°C). Demonstration of these high-performance ECRAMs is a fundamental step toward their implementation in hardware ANNs.
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Affiliation(s)
- A Melianas
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
| | - T J Quill
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - G LeCroy
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Y Tuchman
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - H V Loo
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Zernike Institute for Advanced Materials, University of Groningen, 9747AG Groningen, Netherlands
| | - S T Keene
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - A Giovannitti
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - H R Lee
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - I P Maria
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London, UK
| | - I McCulloch
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London, UK
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center, Thuwal, Saudi Arabia
| | - A Salleo
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
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12
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Crowley RJ, Tan YJ, Ioannidis JPA. Empirical assessment of bias in machine learning diagnostic test accuracy studies. J Am Med Inform Assoc 2020; 27:1092-1101. [PMID: 32548642 PMCID: PMC7647361 DOI: 10.1093/jamia/ocaa075] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/12/2020] [Accepted: 04/24/2020] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Machine learning (ML) diagnostic tools have significant potential to improve health care. However, methodological pitfalls may affect diagnostic test accuracy studies used to appraise such tools. We aimed to evaluate the prevalence and reporting of design characteristics within the literature. Further, we sought to empirically assess whether design features may be associated with different estimates of diagnostic accuracy. MATERIALS AND METHODS We systematically retrieved 2 × 2 tables (n = 281) describing the performance of ML diagnostic tools, derived from 114 publications in 38 meta-analyses, from PubMed. Data extracted included test performance, sample sizes, and design features. A mixed-effects metaregression was run to quantify the association between design features and diagnostic accuracy. RESULTS Participant ethnicity and blinding in test interpretation was unreported in 90% and 60% of studies, respectively. Reporting was occasionally lacking for rudimentary characteristics such as study design (28% unreported). Internal validation without appropriate safeguards was used in 44% of studies. Several design features were associated with larger estimates of accuracy, including having unreported (relative diagnostic odds ratio [RDOR], 2.11; 95% confidence interval [CI], 1.43-3.1) or case-control study designs (RDOR, 1.27; 95% CI, 0.97-1.66), and recruiting participants for the index test (RDOR, 1.67; 95% CI, 1.08-2.59). DISCUSSION Significant underreporting of experimental details was present. Study design features may affect estimates of diagnostic performance in the ML diagnostic test accuracy literature. CONCLUSIONS The present study identifies pitfalls that threaten the validity, generalizability, and clinical value of ML diagnostic tools and provides recommendations for improvement.
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Affiliation(s)
- Ryan J Crowley
- Meta-Research Innovation Center at Stanford, Stanford University, Stanford, California, USA
- Department of Bioengineering, Stanford School of Engineering, Stanford University, Stanford, California, USA
| | - Yuan Jin Tan
- Meta-Research Innovation Center at Stanford, Stanford University, Stanford, California, USA
- Department of Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California, USA
| | - John P A Ioannidis
- Meta-Research Innovation Center at Stanford, Stanford University, Stanford, California, USA
- Department of Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California, USA
- Stanford Prevention Research Center, Department of Medicine, Stanford Medicine, Stanford University, Stanford, California, USA
- Department of Biomedical Data Science, Stanford Medicine, Stanford University, Stanford, California, USA
- Department of Statistics, School of Humanities and Science, Stanford University, Stanford, California, USA
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13
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Abstract
We study the problem of fairly dividing a heterogeneous resource, commonly known as cake cutting and chore division, in the presence of strategic agents. While a number of results in this setting have been established in previous works, they rely crucially on the free disposal assumption, meaning that the mechanism is allowed to throw away part of the resource at no cost. In the present work, we remove this assumption and focus on mechanisms that always allocate the entire resource. We exhibit a truthful and envy-free mechanism for cake cutting and chore division for two agents with piecewise uniform valuations, and we complement our result by showing that such a mechanism does not exist when certain additional constraints are imposed on the mechanisms. Moreover, we provide bounds on the efficiency of mechanisms satisfying various properties, and give truthful mechanisms for multiple agents with restricted classes of valuations.
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Affiliation(s)
- Xiaohui Bei
- Nanyang Technological University, Singapore, Singapore
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14
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Simpson CS, Welker CG, Uhlrich SD, Sketch SM, Jackson RW, Delp SL, Collins SH, Selinger JC, Hawkes EW. Connecting the legs with a spring improves human running economy. J Exp Biol 2019; 222:jeb202895. [PMID: 31395676 PMCID: PMC6765174 DOI: 10.1242/jeb.202895] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/01/2019] [Indexed: 12/20/2022]
Abstract
Human running is inefficient. For every 10 calories burned, less than 1 is needed to maintain a constant forward velocity - the remaining energy is, in a sense, wasted. The majority of this wasted energy is expended to support the bodyweight and redirect the center of mass during the stance phase of gait. An order of magnitude less energy is expended to brake and accelerate the swinging leg. Accordingly, most devices designed to increase running efficiency have targeted the costlier stance phase of gait. An alternative approach is seen in nature: spring-like tissues in some animals and humans are believed to assist leg swing. While it has been assumed that such a spring simply offloads the muscles that swing the legs, thus saving energy, this mechanism has not been experimentally investigated. Here, we show that a spring, or 'exotendon', connecting the legs of a human reduces the energy required for running by 6.4±2.8%, and does so through a complex mechanism that produces savings beyond those associated with leg swing. The exotendon applies assistive forces to the swinging legs, increasing the energy optimal stride frequency. Runners then adopt this frequency, taking faster and shorter strides, and reduce the joint mechanical work to redirect their center of mass. Our study shows how a simple spring improves running economy through a complex interaction between the changing dynamics of the body and the adaptive strategies of the runner, highlighting the importance of considering each when designing systems that couple human and machine.
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Affiliation(s)
- Cole S Simpson
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
| | - Cara G Welker
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
- Stanford University, Department of Bioengineering, Stanford, CA 94305, USA
| | - Scott D Uhlrich
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
| | - Sean M Sketch
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
| | - Rachel W Jackson
- Stanford University, Department of Bioengineering, Stanford, CA 94305, USA
| | - Scott L Delp
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
- Stanford University, Department of Bioengineering, Stanford, CA 94305, USA
| | - Steve H Collins
- Stanford University, Department of Mechanical Engineering, Stanford, CA 94305, USA
| | - Jessica C Selinger
- Stanford University, Department of Bioengineering, Stanford, CA 94305, USA
- Queen's University, School of Kinesiology and Health Studies, Kingston, ON K7L 3N6, Canada
| | - Elliot W Hawkes
- University of California, Santa Barbara, Department of Mechanical Engineering, Santa Barbara, CA 93106, USA
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15
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Abstract
Cerebral atrophy in response to traumatic brain injury is a well-documented phenomenon in both primary investigations and review articles. Recent atrophy studies focus on exploring the region-specific patterns of cerebral atrophy; yet, there is no study that analyzes and synthesizes the emerging atrophy patterns in a single comprehensive review. Here we attempt to fill this gap in our current knowledge by integrating the current literature into a cohesive theory of preferential brain tissue loss and by identifying common risk factors for accelerated atrophy progression. Our review reveals that observations for mild traumatic brain injury remain inconclusive, whereas observations for moderate-to-severe traumatic brain injury converge towards robust patterns: brain tissue loss is on the order of 5% per year, and occurs in the form of generalized atrophy, across the entire brain, or focal atrophy, in specific brain regions. The most common regions of focal atrophy are the thalamus, hippocampus, and cerebellum in gray matter and the corpus callosum, corona radiata, and brainstem in white matter. We illustrate the differences of generalized and focal gray and white matter atrophy on emerging deformation and stress profiles across the whole brain using computational simulation. The characteristic features of our atrophy simulations-a widening of the cortical sulci, a gradual enlargement of the ventricles, and a pronounced cortical thinning-agree well with clinical observations. Understanding region-specific atrophy patterns in response to traumatic brain injury has significant implications in modeling, simulating, and predicting injury outcomes. Computational modeling of brain atrophy could open new strategies for physicians to make informed decisions for whom, how, and when to administer pharmaceutical treatment to manage the chronic loss of brain structure and function.
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16
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Abstract
Tournament solutions provide methods for selecting the "best" alternatives from a tournament and have found applications in a wide range of areas. Previous work has shown that several well-known tournament solutions almost never rule out any alternative in large random tournaments. Nevertheless, all analytical results thus far have assumed a rigid probabilistic model, in which either a tournament is chosen uniformly at random, or there is a linear order of alternatives and the orientation of all edges in the tournament is chosen with the same probabilities according to the linear order. In this work, we consider a significantly more general model where the orientation of different edges can be chosen with different probabilities. We show that a number of common tournament solutions, including the top cycle and the uncovered set, are still unlikely to rule out any alternative under this model. This corresponds to natural graph-theoretic conditions such as irreducibility of the tournament. In addition, we provide tight asymptotic bounds on the boundary of the probability range for which the tournament solutions select all alternatives with high probability.
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17
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Faralla C, Bastounis EE, Ortega FE, Light SH, Rizzuto G, Gao L, Marciano DK, Nocadello S, Anderson WF, Robbins JR, Theriot JA, Bakardjiev AI. Listeria monocytogenes InlP interacts with afadin and facilitates basement membrane crossing. PLoS Pathog 2018; 14:e1007094. [PMID: 29847585 PMCID: PMC6044554 DOI: 10.1371/journal.ppat.1007094] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/13/2018] [Accepted: 05/11/2018] [Indexed: 12/14/2022] Open
Abstract
During pregnancy, the placenta protects the fetus against the maternal immune response, as well as bacterial and viral pathogens. Bacterial pathogens that have evolved specific mechanisms of breaching this barrier, such as Listeria monocytogenes, present a unique opportunity for learning how the placenta carries out its protective function. We previously identified the L. monocytogenes protein Internalin P (InlP) as a secreted virulence factor critical for placental infection. Here, we show that InlP, but not the highly similar L. monocytogenes internalin Lmo2027, binds to human afadin (encoded by AF-6), a protein associated with cell-cell junctions. A crystal structure of InlP reveals several unique features, including an extended leucine-rich repeat (LRR) domain with a distinctive Ca2+-binding site. Despite afadin's involvement in the formation of cell-cell junctions, MDCK epithelial cells expressing InlP displayed a decrease in the magnitude of the traction stresses they could exert on deformable substrates, similar to the decrease in traction exhibited by AF-6 knock-out MDCK cells. L. monocytogenes ΔinlP mutants were deficient in their ability to form actin-rich protrusions from the basal face of polarized epithelial monolayers, a necessary step in the crossing of such monolayers (transcytosis). A similar phenotype was observed for bacteria expressing an internal in-frame deletion in inlP (inlP ΔLRR5) that specifically disrupts its interaction with afadin. However, afadin deletion in the host cells did not rescue the transcytosis defect. We conclude that secreted InlP targets cytosolic afadin to specifically promote L. monocytogenes transcytosis across the basal face of epithelial monolayers, which may contribute to the crossing of the basement membrane during placental infection.
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Affiliation(s)
- Cristina Faralla
- Benioff Children’s Hospital, University of California, San Francisco, San Francisco, California, United States of America
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, California, United States of America
| | - Effie E. Bastounis
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Fabian E. Ortega
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Samuel H. Light
- Center for Structural Genomics of Infectious Diseases and Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Gabrielle Rizzuto
- Benioff Children’s Hospital, University of California, San Francisco, San Francisco, California, United States of America
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, California, United States of America
- Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America
| | - Lei Gao
- Department of Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Denise K. Marciano
- Department of Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Salvatore Nocadello
- Center for Structural Genomics of Infectious Diseases and Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Wayne F. Anderson
- Center for Structural Genomics of Infectious Diseases and Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Jennifer R. Robbins
- Department of Biology, Xavier University, Cincinnati, Ohio, United States of America
| | - Julie A. Theriot
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - Anna I. Bakardjiev
- Benioff Children’s Hospital, University of California, San Francisco, San Francisco, California, United States of America
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, California, United States of America
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18
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Abstract
Birds frequently hop and fly between tree branches to forage. To determine the mechanical energy trade-offs of their bimodal locomotion, we rewarded four Pacific parrotlets with a seed for flying voluntarily between instrumented perches inside a new aerodynamic force platform. By integrating direct measurements of both leg and wing forces with kinematics in a bimodal long jump and flight model, we discovered that parrotlets direct their leg impulse to minimize the mechanical energy needed to forage over different distances and inclinations. The bimodal locomotion model further shows how even a small lift contribution from a single proto-wingbeat would have significantly lengthened the long jump of foraging arboreal dinosaurs. These avian bimodal locomotion strategies can also help robots traverse cluttered environments more effectively.
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