53 results on '"Calvin K. Lee"'
Search Results
2. How P. aeruginosa cells with diverse stator composition collectively swarm
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Jaime de Anda, Sherry L. Kuchma, Shanice S. Webster, Arman Boromand, Kimberley A. Lewis, Calvin K. Lee, Maria Contreras, Victor F. Medeiros Pereira, William Schmidt, Deborah A. Hogan, Corey S. O’Hern, George A. O’Toole, and Gerard C. L. Wong
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swarming ,heterogeneous populations ,unjamming ,stators ,flagellar motility ,flagellar shut-down ,Microbiology ,QR1-502 - Abstract
ABSTRACTSwarming is a macroscopic phenomenon in which surface bacteria organize into a motile population. The flagellar motor that drives swarming in Pseudomonas aeruginosa is powered by stators MotAB and MotCD. Deletion of the MotCD stator eliminates swarming, whereas deletion of the MotAB stator enhances swarming. Interestingly, we measured a strongly asymmetric stator availability in the wild-type (WT) strain, with MotAB stators produced at an approximately 40-fold higher level than MotCD stators. However, utilization of MotCD stators in free swimming cells requires higher liquid viscosities, while MotAB stators are readily utilized at low viscosities. Importantly, we find that cells with MotCD stators are ~10× more likely to have an active motor compared to cells uses the MotAB stators. The spectrum of motility intermittency can either cooperatively shut down or promote flagellum motility in WT populations. In P. aeruginosa, transition from a static solid-like biofilm to a dynamic liquid-like swarm is not achieved at a single critical value of flagellum torque or stator fraction but is collectively controlled by diverse combinations of flagellum activities and motor intermittencies via dynamic stator utilization. Experimental and computational results indicate that the initiation or arrest of flagellum-driven swarming motility does not occur from individual fitness or motility performance but rather related to concepts from the “jamming transition” in active granular matter.IMPORTANCEIt is now known that there exist multifactorial influences on swarming motility for P. aeruginosa, but it is not clear precisely why stator selection in the flagellum motor is so important. We show differential production and utilization of the stators. Moreover, we find the unanticipated result that the two motor configurations have significantly different motor intermittencies: the fraction of flagellum-active cells in a population on average with MotCD is active ~10× more often than with MotAB. What emerges from this complex landscape of stator utilization and resultant motor output is an intrinsically heterogeneous population of motile cells. We show how consequences of stator recruitment led to swarming motility and how the stators potentially relate to surface sensing circuitry.
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- 2024
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3. Force-Induced Changes of PilY1 Drive Surface Sensing by Pseudomonas aeruginosa
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Shanice S. Webster, Marion Mathelié-Guinlet, Andreia F. Verissimo, Daniel Schultz, Albertus Viljoen, Calvin K. Lee, William C. Schmidt, Gerard C. L. Wong, Yves F. Dufrêne, and George A. O’Toole
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type 4 pili ,force ,PilY1 ,von Willebrand A domain ,surface sensing ,c-di-GMP ,Microbiology ,QR1-502 - Abstract
ABSTRACT During biofilm formation, the opportunistic pathogen Pseudomonas aeruginosa uses its type IV pili (TFP) to sense a surface, eliciting increased second-messenger production and regulating target pathways required to adapt to a surface lifestyle. The mechanisms whereby TFP detect surface contact are still poorly understood, although mechanosensing is often invoked, with few data supporting this claim. Using a combination of molecular genetics and single-cell analysis, with biophysical, biochemical, and genomics techniques, we show that force-induced changes mediated by the von Willebrand A (vWA) domain-containing, TFP tip-associated protein PilY1 are required for surface sensing. Atomic force microscopy shows that TFP/PilY1 can undergo force-induced, sustained conformational changes akin to those observed for mechanosensitive proteins like titin. We show that mutation of a single cysteine residue in the vWA domain of PilY1 results in modestly lower surface adhesion forces, reduced sustained conformational changes, and increased nanospring-like properties, as well as reduced c-di-GMP signaling and biofilm formation. Mutating this cysteine has allowed us to genetically separate a role for TFP in twitching motility from surface-sensing signaling. The conservation of this Cys residue in all P. aeruginosa PA14 strains and its absence in the ∼720 sequenced strains of P. aeruginosa PAO1 may contribute to explaining the observed differences in surface colonization strategies observed for PA14 versus PAO1. IMPORTANCE Most bacteria live on abiotic and biotic surfaces in surface-attached communities known as biofilms. Surface sensing and increased levels of the second-messenger molecule c-di-GMP are crucial to the transition from planktonic to biofilm growth. The mechanism(s) underlying TFP-mediated surface detection that triggers this c-di-GMP signaling cascade is unclear. Here, we provide key insight into this question; we show that the eukaryote-like vWA domain of the TFP tip-associated protein PilY1 responds to mechanical force, which in turn drives the production of a key second messenger needed to regulate surface behaviors. Our studies highlight a potential mechanism that may account for differing surface colonization strategies.
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- 2022
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4. c-di-GMP modulates type IV MSHA pilus retraction and surface attachment in Vibrio cholerae
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Kyle A. Floyd, Calvin K. Lee, Wujing Xian, Mahmoud Nametalla, Aneesa Valentine, Benjamin Crair, Shiwei Zhu, Hannah Q. Hughes, Jennifer L. Chlebek, Daniel C. Wu, Jin Hwan Park, Ali M. Farhat, Charles J. Lomba, Courtney K. Ellison, Yves V. Brun, Javier Campos-Gomez, Ankur B. Dalia, Jun Liu, Nicolas Biais, Gerard C. L. Wong, and Fitnat H. Yildiz
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Science - Abstract
Biofilm formation by Vibrio cholerae is regulated by c-di-GMP and requires the type IV MSHA pilus. Here, Floyd et al. show that the MSHA pilus is a dynamic system, and that both extension and retraction are directly controlled by c-di-GMP via regulation of activity of the extension ATPase MshE.
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- 2020
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5. Social Cooperativity of Bacteria during Reversible Surface Attachment in Young Biofilms: a Quantitative Comparison of Pseudomonas aeruginosa PA14 and PAO1
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Calvin K. Lee, Jérémy Vachier, Jaime de Anda, Kun Zhao, Amy E. Baker, Rachel R. Bennett, Catherine R. Armbruster, Kimberley A. Lewis, Rebecca L. Tarnopol, Charles J. Lomba, Deborah A. Hogan, Matthew R. Parsek, George A. O’Toole, Ramin Golestanian, and Gerard C. L. Wong
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Pseudomonas aeruginosa ,bacterial biofilms ,reversible attachment ,stochastic model ,surface sensing ,Microbiology ,QR1-502 - Abstract
ABSTRACT What are bacteria doing during “reversible attachment,” the period of transient surface attachment when they initially engage a surface, besides attaching themselves to the surface? Can an attaching cell help any other cell attach? If so, does it help all cells or employ a more selective strategy to help either nearby cells (spatial neighbors) or its progeny (temporal neighbors)? Using community tracking methods at the single-cell resolution, we suggest answers to these questions based on how reversible attachment progresses during surface sensing for Pseudomonas aeruginosa strains PAO1 and PA14. Although PAO1 and PA14 exhibit similar trends of surface cell population increase, they show unanticipated differences when cells are considered at the lineage level and interpreted using the quantitative framework of an exactly solvable stochastic model. Reversible attachment comprises two regimes of behavior, processive and nonprocessive, corresponding to whether cells of the lineage stay on the surface long enough to divide, or not, before detaching. Stark differences between PAO1 and PA14 in the processive regime of reversible attachment suggest the existence of two surface colonization strategies. PAO1 lineages commit quickly to a surface compared to PA14 lineages, with early c-di-GMP-mediated exopolysaccharide (EPS) production that can facilitate the attachment of neighbors. PA14 lineages modulate their motility via cyclic AMP (cAMP) and retain memory of the surface so that their progeny are primed for improved subsequent surface attachment. Based on the findings of previous studies, we propose that the differences between PAO1 and PA14 are potentially rooted in downstream differences between Wsp-based and Pil-Chp-based surface-sensing systems, respectively. IMPORTANCE The initial pivotal phase of bacterial biofilm formation known as reversible attachment, where cells undergo a period of transient surface attachment, is at once universal and poorly understood. What is more, although we know that reversible attachment culminates ultimately in irreversible attachment, it is not clear how reversible attachment progresses phenotypically, as bacterial surface-sensing circuits fundamentally alter cellular behavior. We analyze diverse observed bacterial behavior one family at a time (defined as a full lineage of cells related to one another by division) using a unifying stochastic model and show that our findings lead to insights on the time evolution of reversible attachment and the social cooperative dimension of surface attachment in PAO1 and PA14 strains.
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- 2020
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6. Functional Specialization in Vibrio cholerae Diguanylate Cyclases: Distinct Modes of Motility Suppression and c-di-GMP Production
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David Zamorano-Sánchez, Wujing Xian, Calvin K. Lee, Mauro Salinas, Wiriya Thongsomboon, Lynette Cegelski, Gerard C. L. Wong, and Fitnat H. Yildiz
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biofilm ,motility ,Vibrio cholerae ,c-di-GMP ,Microbiology ,QR1-502 - Abstract
ABSTRACT Vibrio cholerae biofilm formation and associated motility suppression are correlated with increased concentrations of cyclic diguanylate monophosphate (c-di-GMP), which are in turn driven by increased levels and/or activity of diguanylate cyclases (DGCs). To further our understanding of how c-di-GMP modulators in V. cholerae individually and collectively influence motility with cellular resolution, we determined how DGCs CdgD and CdgH impact intracellular c-di-GMP levels, motility, and biofilm formation. Our results indicated that CdgH strongly influences swim speed distributions; cells in which cdgH was deleted had higher average swim speeds than wild-type cells. Furthermore, our results suggest that CdgD, rather than CdgH, is the dominant DGC responsible for postattachment c-di-GMP production in biofilms. Lipopolysaccharide (LPS) biosynthesis genes were found to be extragenic bypass suppressors of the motility phenotypes of strains ΔcdgD and ΔcdgH. We compared the motility regulation mechanism of the DGCs with that of Gmd, an LPS O-antigen biosynthesis protein, and discovered that comodulation of c-di-GMP levels by these motility effectors can be positively or negatively cooperative rather than simply additive. Taken together, these results suggest that different environmental and metabolic inputs orchestrate DGC responses of V. cholerae via c-di-GMP production and motility modulation. IMPORTANCE Cyclic diguanylate monophosphate (c-di-GMP) is a broadly conserved bacterial signaling molecule that affects motility, biofilm formation, and virulence. Although it has been known that high intracellular concentrations of c-di-GMP correlate with motility suppression and biofilm formation, how the 53 predicted c-di-GMP modulators in Vibrio cholerae collectively influence motility is not understood in detail. Here we used a combination of plate assays and single-cell tracking methods to correlate motility and biofilm formation outcomes with specific enzymes involved in c-di-GMP synthesis in Vibrio cholerae, the causative agent of the disease cholera.
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- 2019
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7. Dual receptor T cells mediate effective antitumor immune responses via increased recognition of tumor antigens
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Lu Wang, Christine Caron, Gerald P Morris, Hyun J Jang, Calvin K Lee, Burhan Jama, and Jack D Bui
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background Discovery that ~16% of T cells naturally co-express two T-cell receptor (TCR) clonotypes prompts examining the role of dual TCR cells in immune functions.Methods Using TCRα-reporter transgenic mice, enabling unambiguous identification of single-TCR and dual-TCR cells, we tested the role of dual TCR cells in antitumor immune responses against immune-responsive syngeneic 6727 sarcoma and immune-resistant B16F10 melanoma.Results Dual TCR cells were specifically increased among tumor-infiltrating lymphocytes (TILs) in both models, indicating selective advantage in antitumor responses. Phenotype and single-cell gene expression analyses identified dual TCR are predominant during the effective antitumor response, demonstrating selectively increased activation in the TIL compartment and skewing toward an effector memory phenotype. Absence of dual TCR cells impaired immune response to B16F10 but not 6727, suggesting that dual TCR cells may be more influential in responses against poorly immunogenic tumors. Dual TCR cells demonstrated an advantage in recognition of B16F10-derived neoantigens in vitro, providing a mechanistic basis for their antitumor reactivity.Conclusions These results discover an unrecognized role for dual TCR cells in protective immune function and identify these cells and their TCRs as a potential resource for antitumor immunotherapy.
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- 2023
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8. Correction: Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations
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Catherine R Armbruster, Calvin K Lee, Jessica Parker-Gilham, Jaime de Anda, Aiguo Xia, Kun Zhao, Keiji Murakami, Boo Shan Tseng, Lucas R Hoffman, Fan Jin, Caroline S Harwood, Gerard CL Wong, and Matthew R Parsek
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Medicine ,Science ,Biology (General) ,QH301-705.5 - Published
- 2020
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9. Reciprocal c-di-GMP signaling: Incomplete flagellum biogenesis triggers c-di-GMP signaling pathways that promote biofilm formation.
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Daniel C Wu, David Zamorano-Sánchez, Fernando A Pagliai, Jin Hwan Park, Kyle A Floyd, Calvin K Lee, Giordan Kitts, Christopher B Rose, Eric M Bilotta, Gerard C L Wong, and Fitnat H Yildiz
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Genetics ,QH426-470 - Abstract
The assembly status of the V. cholerae flagellum regulates biofilm formation, suggesting that the bacterium senses a lack of movement to commit to a sessile lifestyle. Motility and biofilm formation are inversely regulated by the second messenger molecule cyclic dimeric guanosine monophosphate (c-di-GMP). Therefore, we sought to define the flagellum-associated c-di-GMP-mediated signaling pathways that regulate the transition from a motile to a sessile state. Here we report that elimination of the flagellum, via loss of the FlaA flagellin, results in a flagellum-dependent biofilm regulatory (FDBR) response, which elevates cellular c-di-GMP levels, increases biofilm gene expression, and enhances biofilm formation. The strength of the FDBR response is linked with status of the flagellar stator: it can be reversed by deletion of the T ring component MotX, and reduced by mutations altering either the Na+ binding ability of the stator or the Na+ motive force. Absence of the stator also results in reduction of mannose-sensitive hemagglutinin (MSHA) pilus levels on the cell surface, suggesting interconnectivity of signal transduction pathways involved in biofilm formation. Strains lacking flagellar rotor components similarly launched an FDBR response, however this was independent of the status of assembly of the flagellar stator. We found that the FDBR response requires at least three specific diguanylate cyclases that contribute to increased c-di-GMP levels, and propose that activation of biofilm formation during this response relies on c-di-GMP-dependent activation of positive regulators of biofilm production. Together our results dissect how flagellum assembly activates c-di-GMP signaling circuits, and how V. cholerae utilizes these signals to transition from a motile to a sessile state.
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- 2020
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10. cis-B7:CD28 interactions at invaginated synaptic membranes provide CD28 co-stimulation and promote CD8+ T cell function and anti-tumor immunity
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Yunlong Zhao, Christine Caron, Ya-Yuan Chan, Calvin K. Lee, Xiaozheng Xu, Jibin Zhang, Takeya Masubuchi, Chuan Wu, Jack D. Bui, and Enfu Hui
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Infectious Diseases ,Immunology ,Immunology and Allergy - Published
- 2023
11. Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations
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Catherine R Armbruster, Calvin K Lee, Jessica Parker-Gilham, Jaime de Anda, Aiguo Xia, Kun Zhao, Keiji Murakami, Boo Shan Tseng, Lucas R Hoffman, Fan Jin, Caroline S Harwood, Gerard CL Wong, and Matthew R Parsek
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Pseudomonas aeruginosa ,biofilm ,c-di-gmp ,surface sensing ,Wsp system ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition between planktonic and biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. Current thinking in the field is that once cells attach to a surface, they uniformly respond by producing c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment, P. aeruginosa engages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration.
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- 2019
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12. Silver nanoparticles boost charge-extraction efficiency in Shewanella microbial fuel cells
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Kenneth H. Nealson, Xun Guan, Gerard C. L. Wong, Zipeng Zhao, Jin Huang, Calvin K. Lee, Bocheng Cao, Xiaoyang Fu, Xiangfeng Duan, Dan Zhu, Chong Liu, Mengning Ding, Lele Peng, Frank Song, Yu Huang, Paul S. Weiss, and Hui-Ying Shiu
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chemistry.chemical_classification ,Multidisciplinary ,Microbial fuel cell ,biology ,biology.organism_classification ,Shewanella ,Silver nanoparticle ,Chemical energy ,Electricity generation ,chemistry ,Chemical engineering ,Organic matter ,Sewage treatment ,Bioelectric Energy Sources - Abstract
Silver in the linings The bacterium Shewanella oneidensis is well known to use extracellular electron sinks, metal oxides and ions in nature or electrodes when cultured in a fuel cell, to power the catabolism of organic material. However, the power density of microbial fuel cells has been limited by various factors that are mostly related to connecting the microbes to the anode. Cao et al . found that a reduced graphene oxide–silver nanoparticle anode circumvents some of these issues, providing a substantial increase in current and power density (see the Perspective by Gaffney and Minteer). Electron microscopy revealed silver nanoparticles embedded or attached to the outer cell membrane, possibly facilitating electron transfer from internal electron carriers to the anode. —MAF
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- 2021
13. Dual receptor T cells mediate effective antitumor immune responses via increased recognition of tumor antigens
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Hyun J Jang, Christine Caron, Calvin K Lee, Lu Wang, Burhan Jama, Jack D Bui, and Gerald P Morris
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Cancer Research ,T-Lymphocytes ,1.1 Normal biological development and functioning ,Immunology ,Adaptive Immunity ,Vaccine Related ,Mice ,Underpinning research ,Receptors ,Genetics ,Animals ,2.1 Biological and endogenous factors ,Immunology and Allergy ,Antigens ,Aetiology ,Melanoma ,Cancer ,Pharmacology ,Inflammatory and immune system ,Immunity ,T-Cell ,Oncology ,Antigen ,Neoplasm ,Molecular Medicine ,Immunization ,Immunotherapy - Abstract
BackgroundDiscovery that ~16% of T cells naturally co-express two T-cell receptor (TCR) clonotypes prompts examining the role of dual TCR cells in immune functions.MethodsUsing TCRα-reporter transgenic mice, enabling unambiguous identification of single-TCR and dual-TCR cells, we tested the role of dual TCR cells in antitumor immune responses against immune-responsive syngeneic 6727 sarcoma and immune-resistant B16F10 melanoma.ResultsDual TCR cells were specifically increased among tumor-infiltrating lymphocytes (TILs) in both models, indicating selective advantage in antitumor responses. Phenotype and single-cell gene expression analyses identified dual TCR are predominant during the effective antitumor response, demonstrating selectively increased activation in the TIL compartment and skewing toward an effector memory phenotype. Absence of dual TCR cells impaired immune response to B16F10 but not 6727, suggesting that dual TCR cells may be more influential in responses against poorly immunogenic tumors. Dual TCR cells demonstrated an advantage in recognition of B16F10-derived neoantigens in vitro, providing a mechanistic basis for their antitumor reactivity.ConclusionsThese results discover an unrecognized role for dual TCR cells in protective immune function and identify these cells and their TCRs as a potential resource for antitumor immunotherapy.
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- 2023
14. Abstract 606: Cis-B7:CD28 interactions at invaginated synaptic membranes activate CD28 and promote T cell function
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Yunlong Zhao, Christine Caron, Ya-Yuan Chan, Calvin K. Lee, Xiaozheng Xu, Jack D. Bui, and Enfu Hui
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Cancer Research ,Oncology - Abstract
Absence of adequate CD28 costimulation is a common feature of dysfunctional T cells in cancer. However, although augmentation of CD28 signaling is well known to be essential for restoring dysfunctional T cell immune responses upon immune checkpoint blockade treatment, it is unclear how CD28 in tumor-infiltrated T cells is activated in the absence of corresponding ligands on cancer. In current dogma, the T cell CD28 can be activated in trans by CD80 (B7-1) or CD86 (B7-2) expressed on professional antigen presenting cells (APCs) enriched in secondary lymphoid organs. Notably, besides professional APCs, B7 ligands are also displayed by T cells, but their functions are unclear. Here we report that B7 ligands expressed on T cells interact with CD28 in cis at membrane invaginations of the immunological synapse, as a result of phosphoinositide-3-kinase (PI3K) mediated membrane remodeling. Cis-B7:CD28 interactions triggered CD28 signaling through protein-kinase-C-theta (PKCθ) and promoted T cell survival, migration and cytokine production. In a B7 deficient tumor model grafted with primed CD8+ T cells, blockade of T cell intrinsic B7:CD28 interactions accelerated tumor growth and decreased intratumoral T cells. Thus, B7 ligands on T cells can evoke cell autonomous CD28 costimulation in cis in peripheral tissues, suggesting cis-signaling as a general mechanism for boosting T cell functionality. Citation Format: Yunlong Zhao, Christine Caron, Ya-Yuan Chan, Calvin K. Lee, Xiaozheng Xu, Jack D. Bui, Enfu Hui. Cis-B7:CD28 interactions at invaginated synaptic membranes activate CD28 and promote T cell function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 606.
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- 2023
15. Force-Induced Changes of PilY1 Drive Surface Sensing by Pseudomonas aeruginosa
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Yves F. Dufrêne, Shanice S. Webster, Daniel Schultz, Albertus Viljoen, Marion Mathelié-Guinlet, George A. O'Toole, Gerard C. L. Wong, William C. Schmidt, Calvin K. Lee, Andreia F. Verissimo, and UCL - SST/LIBST - Louvain Institute of Biomolecular Science and Technology
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PilY1 ,medicine.disease_cause ,Microbiology ,Pilus ,type 4 pili ,Single-cell analysis ,Virology ,von Willebrand A domain ,medicine ,biology ,Chemistry ,Pseudomonas aeruginosa ,fungi ,Biofilm ,Adhesion ,c-di-GMP ,biochemical phenomena, metabolism, and nutrition ,surface sensing ,Second messenger system ,Biophysics ,biology.protein ,Mechanosensitive channels ,Titin ,force ,Research Article - Abstract
During biofilm formation, the opportunistic pathogen Pseudomonas aeruginosa uses its type IV pili (TFP) to sense a surface, eliciting increased second messenger production and regulating target pathways required to adapt to a surface lifestyle. The mechanisms whereby TFP detect surface contact is still poorly understood, although mechanosensing is often invoked with little data supporting this claim. Using a combination of molecular genetics and single cell analysis, with biophysical, biochemical and genomics techniques we show that force-induced changes mediated by the von Willebrand A (vWA) domain-containing, TFP tip-associated protein PilY1 are required for surface sensing. Atomic force microscopy shows that PilY1 can undergo force-induced, sustained conformational changes akin to those observed for mechanosensitive proteins like titin. We show that mutation of a single cysteine residue in the vWA domain results in modestly lower surface adhesion forces, increased nanospring-like properties, as well as reduced c-di-GMP signaling and biofilm formation. Mutating this cysteine has allowed us to genetically separate TFP function in twitching from surface sensing signaling. The conservation of this Cys residue in all P. aeruginosa PA14 strains, and its absence in the ~720 sequenced strains of P. aeruginosa PAO1, could contribute to explaining the observed differences in surface colonization strategies observed for PA14 versus PAO1.ImportanceMost bacteria live on abiotic and biotic surfaces in surface-attached communities known as biofilms. Surface sensing and increased levels of the second messenger molecule c-di-GMP are crucial to the transition from planktonic to biofilm growth. The mechanism(s) underlying TFP-mediated surface detection that triggers this c-di-GMP signaling cascade are unclear. Here, we provide a key insight into this question: we show that the eukaryotic-like, vWA domain of the TFP tip-associated protein PilY1 responds to mechanical force, which in turn drives production of a key second messenger needed to regulate surface behaviors. Our studies highlight a potential mechanism that could account for differing surface colonization strategies.
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- 2022
16. Selective Promotion of Adhesion of Shewanella oneidensis on Mannose-Decorated Glycopolymer Surfaces
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Michael Mellody, Gerard C. L. Wong, Paul S. Weiss, Calvin K. Lee, Thomas D. Young, Andrea M. Kasko, and Walter T. Liau
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Materials science ,biology ,Glycopolymer ,Biofilm ,Mannose ,02 engineering and technology ,Adhesion ,010402 general chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,Shewanella ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Cell culture ,Biophysics ,General Materials Science ,Shewanella oneidensis ,0210 nano-technology ,Bacteria - Abstract
Using glycopolymer surfaces, we have stimulated Shewanella oneidensis bacterial colonization and induced where the bacteria attach on a molecular pattern. When adherent bacteria were rinsed with methyl α-d-mannopyranoside, the glycopolymer-functionalized surfaces retained more cells than self-assembled monolayers terminated by a single mannose unit. These results suggest that the three-dimensional multivalency of the glycopolymers both promotes and retains bacterial attachment. When the methyl α-d-mannopyranoside competitor was codeposited with the cell culture, however, the mannose-based polymer was not significantly different from bare gold surfaces. The necessity for equilibration between methyl α-d-mannopyranoside and the cell culture to remove the enhancement suggests that the retention of cells on glycopolymer surfaces is kinetically controlled and is not a thermodynamic result of the cluster glycoside effect. The MshA lectin appears to facilitate the improved adhesion observed. Our findings that the surfaces studied here can induce stable initial attachment and influence the ratio of bacterial strains on the surface may be applied to harness useful microbial communities.
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- 2020
17. Broadcasting of amplitude- and frequency-modulated c-di-GMP signals facilitates cooperative surface commitment in bacterial lineages
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Calvin K. Lee, William C. Schmidt, Shanice S. Webster, Jonathan W. Chen, George A. O’Toole, and Gerard C. L. Wong
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Multidisciplinary ,bacteria biofilms ,cyclic-di-GMP ,Biological Sciences ,Bacterial Physiological Phenomena ,Microbiology ,Applied Physical Sciences ,Bacterial Proteins ,surface sensing ,motility ,Clinical Research ,Mutation ,Pseudomonas aeruginosa ,Physical Sciences ,2.1 Biological and endogenous factors ,Aetiology ,Cyclic GMP ,Protein Binding ,Signal Transduction - Abstract
Significance It is well known that c-di-GMP concentration rises in surface-sensing bacteria and functions as a “molecular switch” for biofilm formation. Here, we provide an important recasting of this picture: Intracellular c-di-GMP signals do not just increase in surface-sensing bacteria; such signals are cooperatively broadcast across multiple generations of cells in a lineage with oscillations that undergo both amplitude and frequency modulation, which are controlled by the coupling between pili appendages and c-di-GMP synthesis machinery. The right “tuning” of these signals in terms of frequency and amplitude correlates ultimately to surface commitment. Amplitude and frequency modulation of c-di-GMP signals allows encoding of more complex instructions. Thus, our work provides a more nuanced understanding of how c-di-GMP signaling drives surface commitment., Work on surface sensing in bacterial biofilms has focused on how cells transduce sensory input into cyclic diguanylate (c-di-GMP) signaling, low and high levels of which generally correlate with high-motility planktonic cells and low-motility biofilm cells, respectively. Using Granger causal inference methods, however, we find that single-cell c-di-GMP increases are not sufficient to imply surface commitment. Tracking entire lineages of cells from the progenitor cell onward reveals that c-di-GMP levels can exhibit increases but also undergo oscillations that can propagate across 10 to 20 generations, thereby encoding more complex instructions for community behavior. Principal component and factor analysis of lineage c-di-GMP data shows that surface commitment behavior correlates with three statistically independent composite features, which roughly correspond to mean c-di-GMP levels, c-di-GMP oscillation period, and surface motility. Surface commitment in young biofilms does not correlate to c-di-GMP increases alone but also to the emergence of high-frequency and small-amplitude modulation of elevated c-di-GMP signal along a lineage of cells. Using this framework, we dissect how increasing or decreasing signal transduction from wild-type levels, by varying the interaction strength between PilO, a component of a principal surface sensing appendage system, and SadC, a key hub diguanylate cyclase that synthesizes c-di-GMP, impacts frequency and amplitude modulation of c-di-GMP signals and cooperative surface commitment.
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- 2021
18. Silver nanoparticles boost charge-extraction efficiency in
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Bocheng, Cao, Zipeng, Zhao, Lele, Peng, Hui-Ying, Shiu, Mengning, Ding, Frank, Song, Xun, Guan, Calvin K, Lee, Jin, Huang, Dan, Zhu, Xiaoyang, Fu, Gerard C L, Wong, Chong, Liu, Kenneth, Nealson, Paul S, Weiss, Xiangfeng, Duan, and Yu, Huang
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Shewanella ,Silver ,Electricity ,Bioelectric Energy Sources ,Biofilms ,Dielectric Spectroscopy ,Electric Impedance ,Metal Nanoparticles ,Electrons ,Graphite ,Electrodes - Abstract
Microbial fuel cells (MFCs) can directly convert the chemical energy stored in organic matter to electricity and are of considerable interest for power generation and wastewater treatment. However, the current MFCs typically exhibit unsatisfactorily low power densities that are largely limited by the sluggish transmembrane and extracellular electron-transfer processes. Here, we report a rational strategy to boost the charge-extraction efficiency in
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- 2021
19. Interaction between the type 4 pili machinery and a diguanylate cyclase fine-tune c-di-GMP levels during early biofilm formation
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Shanice S. Webster, George A. O'Toole, Calvin K. Lee, Gerard C. L. Wong, and William C. Schmidt
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Mutant ,Amino Acid Motifs ,Motility ,medicine.disease_cause ,Models, Biological ,Pilus ,Type IV Secretion Systems ,03 medical and health sciences ,Bimolecular fluorescence complementation ,Protein Domains ,medicine ,Cyclic GMP ,Conserved Sequence ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,biology ,030306 microbiology ,Chemistry ,Pseudomonas aeruginosa ,Escherichia coli Proteins ,Biofilm ,Biological Sciences ,biology.organism_classification ,Cell biology ,Biofilms ,Fimbriae, Bacterial ,Mutation ,biology.protein ,Diguanylate cyclase ,Phosphorus-Oxygen Lyases ,Single-Cell Analysis ,Bacteria ,Protein Binding ,Signal Transduction - Abstract
To initiate biofilm formation, it is critical for bacteria to sense a surface and respond precisely to activate downstream components of the biofilm program. Type 4 pili (T4P) and increasing levels of c-di-GMP have been shown to be important for surface sensing and biofilm formation, respectively; however, mechanisms important in modulating the levels of this dinucleotide molecule to define a precise output response are unknown. Here, using macroscopic bulk assays and single-cell tracking analyses of Pseudomonas aeruginosa, we uncover a role of the T4P alignment complex protein, PilO, in modulating the activity of the diguanylate cyclase (DGC) SadC. Two-hybrid and bimolecular fluorescence complementation assays, combined with genetic studies, are consistent with a model whereby PilO interacts with SadC and that the PilO-SadC interaction inhibits SadC's activity, resulting in decreased biofilm formation and increased motility. Using single-cell tracking, we monitor both the mean c-di-GMP and the variance of this dinucleotide in individual cells. Mutations that increase PilO-SadC interaction modestly, but significantly, decrease both the average and variance in c-di-GMP levels on a cell-by-cell basis, while mutants that disrupt PilO-SadC interaction increase the mean and variance of c-di-GMP levels. This work is consistent with a model wherein P. aeruginosa uses a component of the T4P scaffold to fine-tune the levels of this dinucleotide signal during surface commitment. Finally, given our previous findings linking SadC to the flagellar machinery, we propose that this DGC acts as a bridge to integrate T4P and flagellar-derived input signals during initial surface engagement.
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- 2021
20. Roadmap on emerging concepts in the physical biology of bacterial biofilms:from surface sensing to community formation
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Nikhil S. Malvankar, Kyle A. Floyd, Knut Drescher, Jing Yan, Yves V. Brun, Alexandre Persat, Haoran Xu, Jaime de Anda, Jörn Dunkel, Jyot D. Antani, Yilin Wu, Masanori Toyofuku, George A. O'Toole, Lori A. Zacharoff, Yutaka Yawata, Allon I. Hochbaum, Marco Kühn, Nobuhiko Nomura, Mohamed Y. El-Naggar, Roman Stocker, Gregory B. Whitfield, Sibel Ebru Yalcin, Ramin Golestanian, Francesco Carrara, Howard A. Stone, Calvin K. Lee, Pushkar P. Lele, Gerard C. L. Wong, Fitnat H. Yildiz, Ned S. Wingreen, Albert Siryaporn, Mauricio D. Rojas-Andrade, Jacinta C. Conrad, Shuai Yang, Jing Chen, Jean Louis Bru, Beiyan Nan, Bonnie L. Bassler, Fan Jin, Leo Eberl, Nina Molin Høyland-Kroghsbo, and William C. Schmidt
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escherichia-coli bacteria ,Biophysics ,antibiotic tolerance ,membrane-vesicles ,Biology ,Bacterial Physiological Phenomena ,Community formation ,Bacterial Adhesion ,03 medical and health sciences ,0302 clinical medicine ,Structural Biology ,Membrane vesicle ,Cellular organization ,Molecular Biology ,pseudomonas-aeruginosa biofilms ,030304 developmental biology ,Self-organization ,Physics ,Cognitive science ,0303 health sciences ,Physical science ,Biofilm ,Quorum Sensing ,Cell Biology ,self-organization ,electron-transport ,adhesion ,motility ,iv pili ,physiology of microbes ,c-di-gmp ,geobacter-sulfurreducens ,biofilms ,cellular organisation ,gliding motility ,030217 neurology & neurosurgery - Abstract
Bacterial biofilms are communities of bacteria that exist as aggregates that can adhere to surfaces or be free-standing. This complex, social mode of cellular organization is fundamental to the physiology of microbes and often exhibits surprising behavior. Bacterial biofilms are more than the sum of their parts: single-cell behavior has a complex relation to collective community behavior, in a manner perhaps cognate to the complex relation between atomic physics and condensed matter physics. Biofilm microbiology is a relatively young field by biology standards, but it has already attracted intense attention from physicists. Sometimes, this attention takes the form of seeing biofilms as inspiration for new physics. In this roadmap, we highlight the work of those who have taken the opposite strategy: we highlight the work of physicists and physical scientists who use physics to engage fundamental concepts in bacterial biofilm microbiology, including adhesion, sensing, motility, signaling, memory, energy flow, community formation and cooperativity. These contributions are juxtaposed with microbiologists who have made recent important discoveries on bacterial biofilms using state-of-the-art physical methods. The contributions to this roadmap exemplify how well physics and biology can be combined to achieve a new synthesis, rather than just a division of labor., Physical Biology, 18 (5), ISSN:1478-3975, ISSN:1478-3967
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- 2021
21. Correction for Zamorano-Sánchez et al., 'Functional Specialization in Vibrio cholerae Diguanylate Cyclases: Distinct Modes of Motility Suppression and c-di-GMP Production'
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Wiriya Thongsomboon, David Zamorano-Sánchez, Calvin K. Lee, Fitnat H. Yildiz, Lynette Cegelski, Gerard C. L. Wong, Wujing Xian, and Mauro Salinas
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Genetics ,Molecular Biology and Physiology ,Motility ,c-di-GMP ,Biology ,medicine.disease_cause ,Microbiology ,QR1-502 ,biofilm ,motility ,Vibrio cholerae ,Virology ,medicine ,Author Correction ,Research Article - Abstract
Cyclic diguanylate monophosphate (c-di-GMP) is a broadly conserved bacterial signaling molecule that affects motility, biofilm formation, and virulence. Although it has been known that high intracellular concentrations of c-di-GMP correlate with motility suppression and biofilm formation, how the 53 predicted c-di-GMP modulators in Vibrio cholerae collectively influence motility is not understood in detail. Here we used a combination of plate assays and single-cell tracking methods to correlate motility and biofilm formation outcomes with specific enzymes involved in c-di-GMP synthesis in Vibrio cholerae, the causative agent of the disease cholera., Vibrio cholerae biofilm formation and associated motility suppression are correlated with increased concentrations of cyclic diguanylate monophosphate (c-di-GMP), which are in turn driven by increased levels and/or activity of diguanylate cyclases (DGCs). To further our understanding of how c-di-GMP modulators in V. cholerae individually and collectively influence motility with cellular resolution, we determined how DGCs CdgD and CdgH impact intracellular c-di-GMP levels, motility, and biofilm formation. Our results indicated that CdgH strongly influences swim speed distributions; cells in which cdgH was deleted had higher average swim speeds than wild-type cells. Furthermore, our results suggest that CdgD, rather than CdgH, is the dominant DGC responsible for postattachment c-di-GMP production in biofilms. Lipopolysaccharide (LPS) biosynthesis genes were found to be extragenic bypass suppressors of the motility phenotypes of strains ΔcdgD and ΔcdgH. We compared the motility regulation mechanism of the DGCs with that of Gmd, an LPS O-antigen biosynthesis protein, and discovered that comodulation of c-di-GMP levels by these motility effectors can be positively or negatively cooperative rather than simply additive. Taken together, these results suggest that different environmental and metabolic inputs orchestrate DGC responses of V. cholerae via c-di-GMP production and motility modulation.
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- 2020
22. Correction: Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations
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Keiji Murakami, Aiguo Xia, Jessica Parker-Gilham, Calvin K. Lee, Boo Shan Tseng, Jaime de Anda, Catherine R. Armbruster, Caroline S. Harwood, Fan Jin, Lucas R. Hoffman, Gerard C. L. Wong, Matthew R. Parsek, and Kun Zhao
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General Immunology and Microbiology ,QH301-705.5 ,Pseudomonas aeruginosa ,Science ,General Neuroscience ,General Medicine ,Biology ,medicine.disease_cause ,General Biochemistry, Genetics and Molecular Biology ,Microbiology ,Infectious disease (medical specialty) ,medicine ,Medicine ,Biology (General) - Published
- 2020
23. Social Cooperativity of Bacteria during Reversible Surface Attachment in Young Biofilms: a Quantitative Comparison of <named-content content-type='genus-species'>Pseudomonas aeruginosa</named-content> PA14 and PAO1
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Jérémy Vachier, Gerard C. L. Wong, Rachel R. Bennett, Deborah A. Hogan, Jaime de Anda, Amy Baker, Kimberley A. Lewis, Rebecca L. Tarnopol, Catherine R. Armbruster, Ramin Golestanian, Kun Zhao, Charles J. Lomba, Matthew R. Parsek, George A. O'Toole, Calvin K. Lee, and Ausubel, Frederick M
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Surface (mathematics) ,Molecular Biology and Physiology ,Lineage (genetic) ,Selective strategy ,Motility ,Cooperativity ,Bacterial Physiological Phenomena ,medicine.disease_cause ,Microbiology ,Bacterial Adhesion ,03 medical and health sciences ,Theoretical ,Bacterial Proteins ,Models ,Virology ,Cyclic AMP ,medicine ,2.2 Factors relating to the physical environment ,Aetiology ,bacterial biofilms ,stochastic model ,030304 developmental biology ,0303 health sciences ,Bacteria ,biology ,030306 microbiology ,Pseudomonas aeruginosa ,Chemistry ,Biofilm ,Models, Theoretical ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,QR1-502 ,Cell biology ,surface sensing ,Biofilms ,reversible attachment ,Research Article - Abstract
The initial pivotal phase of bacterial biofilm formation known as reversible attachment, where cells undergo a period of transient surface attachment, is at once universal and poorly understood. What is more, although we know that reversible attachment culminates ultimately in irreversible attachment, it is not clear how reversible attachment progresses phenotypically, as bacterial surface-sensing circuits fundamentally alter cellular behavior. We analyze diverse observed bacterial behavior one family at a time (defined as a full lineage of cells related to one another by division) using a unifying stochastic model and show that our findings lead to insights on the time evolution of reversible attachment and the social cooperative dimension of surface attachment in PAO1 and PA14 strains., What are bacteria doing during “reversible attachment,” the period of transient surface attachment when they initially engage a surface, besides attaching themselves to the surface? Can an attaching cell help any other cell attach? If so, does it help all cells or employ a more selective strategy to help either nearby cells (spatial neighbors) or its progeny (temporal neighbors)? Using community tracking methods at the single-cell resolution, we suggest answers to these questions based on how reversible attachment progresses during surface sensing for Pseudomonas aeruginosa strains PAO1 and PA14. Although PAO1 and PA14 exhibit similar trends of surface cell population increase, they show unanticipated differences when cells are considered at the lineage level and interpreted using the quantitative framework of an exactly solvable stochastic model. Reversible attachment comprises two regimes of behavior, processive and nonprocessive, corresponding to whether cells of the lineage stay on the surface long enough to divide, or not, before detaching. Stark differences between PAO1 and PA14 in the processive regime of reversible attachment suggest the existence of two surface colonization strategies. PAO1 lineages commit quickly to a surface compared to PA14 lineages, with early c-di-GMP-mediated exopolysaccharide (EPS) production that can facilitate the attachment of neighbors. PA14 lineages modulate their motility via cyclic AMP (cAMP) and retain memory of the surface so that their progeny are primed for improved subsequent surface attachment. Based on the findings of previous studies, we propose that the differences between PAO1 and PA14 are potentially rooted in downstream differences between Wsp-based and Pil-Chp-based surface-sensing systems, respectively.
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- 2020
24. PD-L1:CD80 Cis-Heterodimer Triggers the Co-stimulatory Receptor CD28 While Repressing the Inhibitory PD-1 and CTLA-4 Pathways
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Chia-Hao Lin, Cristina Bonorino, Xiaozheng Xu, Yunlong Zhao, Calvin K. Lee, Changchun Xiao, Zhe Huang, Jack D. Bui, Enfu Hui, Rodrigo Benedetti Gassen, and Li-Fan Lu
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0301 basic medicine ,Programmed Cell Death 1 Receptor ,Lymphocyte Activation ,B7-H1 Antigen ,Jurkat Cells ,Mice ,0302 clinical medicine ,CD80 ,heterodimer ,Neoplasms ,Monoclonal ,PD-1 ,2.1 Biological and endogenous factors ,Immunology and Allergy ,Cytotoxic T cell ,CTLA-4 Antigen ,Aetiology ,Receptor ,Humanized ,Inbred BALB C ,Mice, Inbred BALB C ,Tumor ,CD28 ,hemic and immune systems ,Ligand (biochemistry) ,Cell biology ,Infectious Diseases ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,B7-1 Antigen ,Female ,immunotherapy ,Immunotherapy ,Biotechnology ,Signal Transduction ,PD-L1 ,homodimer ,T cell ,Immunology ,Antineoplastic Agents ,chemical and pharmacologic phenomena ,Biology ,Antibodies, Monoclonal, Humanized ,Trans-endocytosis ,Antibodies ,Article ,Cell Line ,03 medical and health sciences ,CD28 Antigens ,Cell Line, Tumor ,medicine ,Animals ,Humans ,Cis-interaction ,Ipilimumab ,Immune checkpoint ,030104 developmental biology ,HEK293 Cells ,CTLA-4 - Abstract
Combined immunotherapy targeting the immune checkpoint receptors cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death 1 (PD-1), or CTLA-4 and the PD-1 ligand (PD-L1) exhibits superior anti-tumor responses compared with single-agent therapy. Here, we examined the molecular basis for this synergy. Using reconstitution assays with fluorescence readouts, we found that PD-L1 and the CTLA-4 ligand CD80 heterodimerize in cis but not trans. Quantitative biochemistry and cell biology assays revealed that PD-L1:CD80 cis-heterodimerization inhibited both PD-L1:PD-1 and CD80:CTLA-4 interactions through distinct mechanisms but preserved the ability of CD80 to activate the Tcell co-stimulatory receptor CD28. Furthermore, PD-L1 expression on antigen-presenting cells (APCs) prevented CTLA-4-mediated trans-endocytosis of CD80. Atezolizumab (anti-PD-L1), but not anti-PD-1, reduced cell surface expression of CD80 on APCs, and this effect was negated by co-blockade of CTLA-4 with ipilimumab (anti-CTLA-4). Thus, PD-L1 exerts an immunostimulatory effect by repressing the CTLA-4 axis; this has implications to the synergy of anti-PD-L1 and anti-CTLA-4 combination therapy.
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- 2019
25. Phenotypic differences in reversible attachment behavior reveal distinct P. aeruginosa surface colonization strategies
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Kimberley A. Lewis, Charles J. Lomba, Catherine R. Armbruster, Matthew R. Parsek, Ramin Golestanian, J. de Anda, Calvin K. Lee, Rebecca L. Tarnopol, Rachel R. Bennett, Jérémy Vachier, Amy Baker, Kun Zhao, Deborah A. Hogan, Gerard C. L. Wong, and George A. O'Toole
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Surface (mathematics) ,0303 health sciences ,030306 microbiology ,Chemistry ,Lineage (evolution) ,Biofilm ,Motility ,biochemical phenomena, metabolism, and nutrition ,Phenotype ,03 medical and health sciences ,Biophysics ,Colonization ,Sensing system ,Process (anatomy) ,030304 developmental biology - Abstract
Despite possessing the machinery to sense, adhere to, and proliferate on surfaces, it is commonly observed that bacteria initially have a difficult time attaching to a surface. Before forming a bacterial biofilm, planktonic bacteria exhibit a random period of transient surface attachment known as “reversible attachment” which is poorly understood. Using community tracking methods at single-cell resolution, we examine how reversible attachment progresses during initial stages of surface sensing.Pseudomonas aeruginosastrains PAO1 and PA14, which exhibit similar exponential trends of surface cell population increase, show unanticipated differences when the behavior of each cell was considered at the full lineage level and interpreted using the unifying quantitative framework of an exactly solvable stochastic model. Reversible attachment comprises two regimes of behavior, processive and nonprocessive, corresponding to whether cells of the lineage stay on the surface long enough to divide, or not, before detaching. Stark differences between PAO1 and PA14 in the processive regime of reversible attachment suggest the existence of two complementary surface colonization strategies, which are roughly analogous to “immediate-” vs “deferred-gratification” in a prototypical cognitive-affective processing system. PAO1 lineages commit relatively quickly to a surface compared to PA14 lineages. PA14 lineages allow detaching cells to retain memory of the surface so that they are primed for improved subsequent surface attachment. In fact, it is possible to identify motility suppression events in PA14 lineages in the process of surface commitment. We hypothesize that these contrasting strategies are rooted in downstream differences between Wsp-based and Pil-Chp-based surface sensing systems.
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- 2019
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26. Author response: Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations
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Catherine R Armbruster, Calvin K Lee, Jessica Parker-Gilham, Jaime de Anda, Aiguo Xia, Kun Zhao, Keiji Murakami, Boo Shan Tseng, Lucas R Hoffman, Fan Jin, Caroline S Harwood, Gerard CL Wong, and Matthew R Parsek
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- 2019
27. Heterogeneity in surface sensing suggests a division of labor in Pseudomonas aeruginosa populations
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Caroline S. Harwood, Keiji Murakami, Gerard C. L. Wong, Jaime de Anda, Aiguo Xia, Catherine R. Armbruster, Jessica Parker-Gilham, Fan Jin, Lucas R. Hoffman, Kun Zhao, Boo Shan Tseng, Matthew R. Parsek, and Calvin K. Lee
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0301 basic medicine ,QH301-705.5 ,Science ,030106 microbiology ,Motility ,medicine.disease_cause ,Bacterial Adhesion ,General Biochemistry, Genetics and Molecular Biology ,biofilm ,03 medical and health sciences ,Bacterial Proteins ,medicine ,Biology (General) ,Cyclic GMP ,Biofilm growth ,Microbiology and Infectious Disease ,General Immunology and Microbiology ,Chemistry ,Pseudomonas aeruginosa ,General Neuroscience ,Cell Membrane ,Biofilm ,Quorum Sensing ,Correction ,Biofilm matrix ,Gene Expression Regulation, Bacterial ,General Medicine ,Cell biology ,030104 developmental biology ,Wsp system ,surface sensing ,Biofilms ,c-di-gmp ,Second messenger system ,Medicine ,Other ,Sensing system ,Research Article - Abstract
The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition between planktonic and biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. Current thinking in the field is that once cells attach to a surface, they uniformly respond by producing c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment, P. aeruginosa engages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration., eLife digest Bacteria can adopt different lifestyles, depending on the environment in which they grow. They can exist as single cells that are free to explore their environment or group together to form ‘biofilms’. The bacteria in biofilms stick to a surface, and produce a slimy ‘matrix’ that covers and thereby protects them. Biofilms have been found in lung infections that affect people with the genetic disorder cystic fibrosis, and can also form on the surface of medical implants. Because the biofilm lifestyle protects bacteria from the immune system and antimicrobial drugs, learning about how biofilms form could help researchers to discover ways to prevent and treat such infections. Many bacteria switch between the free-living and biofilm lifestyles by altering their levels of a signaling molecule called cyclic diguanylate monophosphate (called c-di-GMP for short). Bacteria living in biofilms have much higher levels of c-di-GMP than their free-living counterparts, and bacteria that have high levels of c-di-GMP produce more biofilm matrix. Bacteria called Pseudomonas aeruginosa use a protein signaling complex called the Wsp system to sense that they are on a surface and increase c-di-GMP production. Questions remained about how quickly this change in production occurs, and whether bacteria pass on their c-di-GMP levels to the new descendant cells when they divide. Armbruster et al. monitored individual cells of P. aeruginosa producing c-di-GMP as they began to form biofilms. Unexpectedly, not all cells increased their c-di-GMP levels when they first attached to a surface. Instead, Armbruster et al. found that there are two populations – high and low c-di-GMP cells – that each perform complementary and important tasks in the early stages of biofilm formation. The high c-di-GMP cells represent ‘biofilm founders’ that start to produce the biofilm matrix, whereas the low c-di-GMP cells represent ‘surface explorers’ that spend more time traveling along the surface. Armbruster et al. found that the Wsp surface sensing system generates these two populations of cells. Moreover, the c-di-GMP levels in a bacterial cell even affect the behavior of the descendant cells that form when it divides. This effect can persist for several cell generations. More work is needed to examine exactly how the biofilm founders and surface explorers interact and influence how biofilms form, and to discover if blocking c-di-GMP signaling prevents biofilm formation. This could ultimately lead to new strategies to prevent and treat infections in humans.
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- 2019
28. Functional Specialization in Vibrio cholerae Diguanylate Cyclases: Distinct Modes of Motility Suppression and c-di-GMP Production
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Gerard C. L. Wong, Wiriya Thongsomboon, David Zamorano-Sánchez, Wujing Xian, Mauro Salinas, Lynette Cegelski, Calvin K. Lee, and Fitnat H. Yildiz
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0303 health sciences ,030306 microbiology ,Effector ,Biofilm ,Virulence ,Motility ,c-di-GMP ,medicine.disease_cause ,Microbiology ,biofilm ,QR1-502 ,3. Good health ,Cell biology ,03 medical and health sciences ,chemistry.chemical_compound ,motility ,Biosynthesis ,chemistry ,Vibrio cholerae ,Virology ,medicine ,Protein biosynthesis ,Intracellular ,030304 developmental biology - Abstract
Vibrio cholerae biofilm formation and associated motility suppression are correlated with increased concentrations of cyclic diguanylate monophosphate (c-di-GMP), which are in turn driven by increased levels and/or activity of diguanylate cyclases (DGCs). To further our understanding of how c-di-GMP modulators in V. cholerae individually and collectively influence motility with cellular resolution, we determined how DGCs CdgD and CdgH impact intracellular c-di-GMP levels, motility, and biofilm formation. Our results indicated that CdgH strongly influences swim speed distributions; cells in which cdgH was deleted had higher average swim speeds than wild-type cells. Furthermore, our results suggest that CdgD, rather than CdgH, is the dominant DGC responsible for postattachment c-di-GMP production in biofilms. Lipopolysaccharide (LPS) biosynthesis genes were found to be extragenic bypass suppressors of the motility phenotypes of strains ΔcdgD and ΔcdgH. We compared the motility regulation mechanism of the DGCs with that of Gmd, an LPS O-antigen biosynthesis protein, and discovered that comodulation of c-di-GMP levels by these motility effectors can be positively or negatively cooperative rather than simply additive. Taken together, these results suggest that different environmental and metabolic inputs orchestrate DGC responses of V. cholerae via c-di-GMP production and motility modulation. IMPORTANCE Cyclic diguanylate monophosphate (c-di-GMP) is a broadly conserved bacterial signaling molecule that affects motility, biofilm formation, and virulence. Although it has been known that high intracellular concentrations of c-di-GMP correlate with motility suppression and biofilm formation, how the 53 predicted c-di-GMP modulators in Vibrio cholerae collectively influence motility is not understood in detail. Here we used a combination of plate assays and single-cell tracking methods to correlate motility and biofilm formation outcomes with specific enzymes involved in c-di-GMP synthesis in Vibrio cholerae, the causative agent of the disease cholera.
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- 2019
29. Functional Specialization in
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David, Zamorano-Sánchez, Wujing, Xian, Calvin K, Lee, Mauro, Salinas, Wiriya, Thongsomboon, Lynette, Cegelski, Gerard C L, Wong, and Fitnat H, Yildiz
- Subjects
Biofilms ,Escherichia coli Proteins ,Gene Expression Regulation, Bacterial ,Phosphorus-Oxygen Lyases ,Cyclic GMP ,Vibrio cholerae ,Gene Deletion ,Locomotion - Published
- 2019
30. PD-L1:CD80 Heterodimer Triggers CD28 While Repressing Both PD-1 and CTLA4 Pathways
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Calvin K. Lee, Zhe Huang, Yunlong Zhao, Changchun Xiao, Jack D. Bui, Enfu Hui, Chia-Hao Lin, Li-Fan Lu, and Xiaozheng Xu
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Chemistry ,medicine.medical_treatment ,T cell ,CD28 ,chemical and pharmacologic phenomena ,Immunotherapy ,Blockade ,Cell biology ,Crosstalk (biology) ,medicine.anatomical_structure ,Atezolizumab ,medicine ,Antigen-presenting cell ,CD80 - Abstract
Combined immunotherapy with anti-PD-1/PD-L1 and anti-CTLA4 has resulted in superior clinical responses compared to single agent therapy. The underlying mechanisms for this synergy have yet to be elucidated and investigations have largely focused on cellular interactions. Herein, we report a molecular crosstalk in which the PD-1 ligand PD-L1 and the CTLA4 ligand CD80 heterodimerize in cis. This heterodimerization blocks both PD-L1:PD-1 and CD80:CTLA4 interactions, but preserves the ability of CD80 to activate the T cell costimulatory receptor CD28. Remarkably, PD-L1 expression on antigen presenting cells (APCs) protects CD80 from CTLA4 mediated trans-endocytosis, and the therapeutic PD-L1 blockade antibody atezolizumab paradoxically downregulates CD80 on APCs, presumably reducing its co-stimulatory ability. Importantly, this effect can be negated by co-blockade of CTLA4 with ipilimumab. Our study reveals an unexpected immune stimulatory role of cis-acting PD-L1 and a mechanism of anti-PD-L1/anti-CTLA4 crosstalk, providing a therapeutic rationale for combination blockade of PD-L1 and CTLA4.
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- 2019
31. Heterogeneity in surface sensing produces a division of labor in Pseudomonas aeruginosa populations
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J. de Anda, Boo Shan Tseng, Caroline S. Harwood, Gerard C. L. Wong, Calvin K. Lee, Matthew R. Parsek, Aiguo Xia, Fan Jin, Lucas R. Hoffman, Jessica Parker-Gilham, and Catherine R. Armbruster
- Subjects
Surface (mathematics) ,Pseudomonas aeruginosa ,Chemistry ,Second messenger system ,medicine ,Biofilm ,Biofilm matrix ,Motility ,medicine.disease_cause ,Sensing system ,Biofilm growth ,Cell biology - Abstract
The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition from planktonic to biofilm growth in many bacterial species.Pseudomonas aeruginosahas two surface sensing systems that produce c-di-GMP in response to surface adherence. The current thinking in the field is that once cells attach to a surface, they uniformly respond with elevated c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment,P. aeruginosaengages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration.
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- 2019
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32. Reciprocal c-di-GMP signaling: Incomplete flagellum biogenesis triggers c-di-GMP signaling pathways that promote biofilm formation
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Calvin K. Lee, Fernando A. Pagliai, Kyle A. Floyd, Fitnat H. Yildiz, Jin Hwan Park, Christopher B. Rose, Giordan Kitts, Eric M. Bilotta, David Zamorano-Sánchez, Gerard C. L. Wong, and Daniel C. Wu
- Subjects
Cancer Research ,Gene Expression ,QH426-470 ,Pathology and Laboratory Medicine ,medicine.disease_cause ,Second Messenger Systems ,Pilus ,0302 clinical medicine ,Medicine and Health Sciences ,Cyclic GMP ,Genetics (clinical) ,0303 health sciences ,Escherichia coli Proteins ,Bacterial Pathogens ,3. Good health ,Cell biology ,Cell Motility ,Flagella ,Medical Microbiology ,Vibrio cholerae ,Second messenger system ,Cellular Structures and Organelles ,Pathogens ,Phosphorus-Oxygen Lyases ,Signal transduction ,Research Article ,Signal Transduction ,Pathogen Motility ,Virulence Factors ,Motility ,Flagellum ,Biology ,Microbiology ,03 medical and health sciences ,Bacterial Proteins ,Gene Types ,Vibrio Cholerae ,Genetics ,medicine ,Microbial Pathogens ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,Vibrio ,030304 developmental biology ,Bacteria ,Organisms ,Biofilm ,Biology and Life Sciences ,Bacteriology ,Cell Biology ,Flagellar Motility ,Gene Expression Regulation, Bacterial ,biochemical phenomena, metabolism, and nutrition ,Biofilms ,Fimbriae, Bacterial ,biology.protein ,Regulator Genes ,Bacterial Biofilms ,030217 neurology & neurosurgery ,Flagellin - Abstract
The assembly status of the V. cholerae flagellum regulates biofilm formation, suggesting that the bacterium senses a lack of movement to commit to a sessile lifestyle. Motility and biofilm formation are inversely regulated by the second messenger molecule cyclic dimeric guanosine monophosphate (c-di-GMP). Therefore, we sought to define the flagellum-associated c-di-GMP-mediated signaling pathways that regulate the transition from a motile to a sessile state. Here we report that elimination of the flagellum, via loss of the FlaA flagellin, results in a flagellum-dependent biofilm regulatory (FDBR) response, which elevates cellular c-di-GMP levels, increases biofilm gene expression, and enhances biofilm formation. The strength of the FDBR response is linked with status of the flagellar stator: it can be reversed by deletion of the T ring component MotX, and reduced by mutations altering either the Na+ binding ability of the stator or the Na+ motive force. Absence of the stator also results in reduction of mannose-sensitive hemagglutinin (MSHA) pilus levels on the cell surface, suggesting interconnectivity of signal transduction pathways involved in biofilm formation. Strains lacking flagellar rotor components similarly launched an FDBR response, however this was independent of the status of assembly of the flagellar stator. We found that the FDBR response requires at least three specific diguanylate cyclases that contribute to increased c-di-GMP levels, and propose that activation of biofilm formation during this response relies on c-di-GMP-dependent activation of positive regulators of biofilm production. Together our results dissect how flagellum assembly activates c-di-GMP signaling circuits, and how V. cholerae utilizes these signals to transition from a motile to a sessile state., Author summary A key regulator of Vibrio cholerae physiology is the nucleotide-based, second messenger cyclic dimeric guanosine monophosphate (c-di-GMP). We found that the status of flagellar biosynthesis at different stages of flagellar assembly modulates c-di-GMP signaling in V. cholerae and identified diguanylate cyclases involved in this regulatory process. The effect of motility status on the cellular c-di-GMP level is partly dependent on the flagellar stator and Na+ flux through the flagellum. Finally, we showed that c-di-GMP-dependent positive regulators of biofilm formation are critical for the signaling cascade that connects motility status to biofilm formation. Our results show that in addition to c-di-GMP promoting motile to biofilm lifestyle switch, “motility status” of V. cholerae modulates c-di-GMP signaling and biofilm formation.
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- 2020
33. Multigenerational memory and adaptive adhesion in early bacterial biofilm communities
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Joshua Keefe, Ramin Golestanian, Jaime de Anda, Rachel R. Bennett, Yun Luo, Ernest Y. Lee, George A. O'Toole, Calvin K. Lee, Jie Ma, Gerard C. L. Wong, Amy Baker, Kun Zhao, and Joshua S Helali
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0301 basic medicine ,Lineage (genetic) ,030106 microbiology ,Cell ,Population ,Motility ,Second Messenger Systems ,Pilus ,Bacterial Adhesion ,Fimbriae ,03 medical and health sciences ,medicine ,Cyclic AMP ,education ,education.field_of_study ,Multidisciplinary ,bacteria biofilms ,type IV pili ,Chemistry ,Biofilm ,Bacterial ,Adhesion ,Biological Sciences ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,surface sensing ,Biofilms ,Pseudomonas aeruginosa ,Intracellular - Abstract
Using multigenerational, single-cell tracking we explore the earliest events of biofilm formation by Pseudomonas aeruginosa During initial stages of surface engagement (≤20 h), the surface cell population of this microbe comprises overwhelmingly cells that attach poorly (∼95% stay
- Published
- 2018
34. Seventeen-Year-Old Male With Gross Hematuria
- Author
-
Deepa Kulkarni, Heather Alden, and Calvin K. Lee
- Subjects
Male ,medicine.medical_specialty ,Adolescent ,business.industry ,Biopsy ,General surgery ,Urinary Bladder ,Headache ,030232 urology & nephrology ,Carcinoma, Papillary ,Gross hematuria ,03 medical and health sciences ,0302 clinical medicine ,Urinary Bladder Neoplasms ,030225 pediatrics ,Pediatrics, Perinatology and Child Health ,medicine ,Humans ,Tomography, X-Ray Computed ,business ,Fatigue ,Hematuria - Published
- 2016
35. High-Speed '4D' Computational Microscopy of Bacterial Surface Motility
- Author
-
Tom Chou, George A. O'Toole, Calvin K. Lee, Xiang Ji, Ernest Y. Lee, Jaime de Anda, Ramin Golestanian, Amy Baker, Andrea M. Armani, Soheil Soltani, Rachel R. Bennett, Gerard C. L. Wong, Mark C. Harrison, and Yun Luo
- Subjects
0301 basic medicine ,Diffraction ,Microscope ,Materials science ,030106 microbiology ,Finite Element Analysis ,Analytical chemistry ,General Physics and Astronomy ,Motility ,Article ,law.invention ,03 medical and health sciences ,Imaging, Three-Dimensional ,law ,Confocal microscopy ,Microscopy ,Molecular motor ,General Materials Science ,Spinning ,General Engineering ,Finite element method ,030104 developmental biology ,Cell Tracking ,Flagella ,Pseudomonas aeruginosa ,Hydrodynamics ,Single-Cell Analysis ,Biological system - Abstract
Bacteria exhibit surface motility modes that play pivotal roles in early-stage biofilm community development, such as type IV pili-driven "twitching" motility and flagellum-driven "spinning" and "swarming" motility. Appendage-driven motility is controlled by molecular motors, and analysis of surface motility behavior is complicated by its inherently 3D nature, the speed of which is too fast for confocal microscopy to capture. Here, we combine electromagnetic field computation and statistical image analysis to generate 3D movies close to a surface at 5 ms time resolution using conventional inverted microscopes. We treat each bacterial cell as a spherocylindrical lens and use finite element modeling to solve Maxwell's equations and compute the diffracted light intensities associated with different angular orientations of the bacterium relative to the surface. By performing cross-correlation calculations between measured 2D microscopy images and a library of computed light intensities, we demonstrate that near-surface 3D movies of Pseudomonas aeruginosa translational and rotational motion are possible at high temporal resolution. Comparison between computational reconstructions and detailed hydrodynamic calculations reveals that P. aeruginosa act like low Reynolds number spinning tops with unstable orbits, driven by a flagellum motor with a torque output of ∼2 pN μm. Interestingly, our analysis reveals that P. aeruginosa can undergo complex flagellum-driven dynamical behavior, including precession, nutation, and an unexpected taxonomy of surface motility mechanisms, including upright-spinning bacteria that diffuse laterally across the surface, and horizontal bacteria that follow helicoidal trajectories and exhibit superdiffusive movements parallel to the surface.
- Published
- 2017
36. Nanoelectronic Investigation Reveals the Electrochemical Basis of Electrical Conductivity in Shewanella and Geobacter
- Author
-
Gongming Wang, Hao Wu, Paul S. Weiss, Kenneth H. Nealson, Thomas D. Young, Hui-Ying Shiu, Mengning Ding, Gerard C. L. Wong, Calvin K. Lee, Shiue-Lin Li, Nathan O. Weiss, Xiangfeng Duan, and Yu Huang
- Subjects
Shewanella ,microbial electrochemistry ,Bioelectric Energy Sources ,General Physics and Astronomy ,microbiome ,Nanotechnology ,02 engineering and technology ,bioelectronics ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Electron Transport ,nanoelectronics ,Electron transfer ,Electrical resistivity and conductivity ,General Materials Science ,Nanoscience & Nanotechnology ,Electrodes ,electrogenic bacteria ,extracellular electron transfer ,biology ,General Engineering ,Biofilm ,Electric Conductivity ,bioelectrochemical system ,021001 nanoscience & nanotechnology ,biology.organism_classification ,Electron transport chain ,0104 chemical sciences ,Chemical physics ,Biofilms ,Electrode ,0210 nano-technology ,Geobacter - Abstract
© 2016 American Chemical Society. The electrical conductivity measured in Shewanella and Geobacter spp. is an intriguing physical property that is the fundamental basis for possible extracellular electron transport (EET) pathways. There is considerable debate regarding the origins of the electrical conductivity reported in these microbial cellular structures, which is essential for deciphering the EET mechanism. Here, we report systematic on-chip nanoelectronic investigations of both Shewanella and Geobacter spp. under physiological conditions to elucidate the complex basis of electrical conductivity of both individual microbial cells and biofilms. Concurrent electrical and electrochemical measurements of living Shewanella at both few-cell and the biofilm levels indicate that the apparent electrical conductivity can be traced to electrochemical-based electron transfer at the cell/electrode interface. We further show that similar results and conclusions apply to the Geobacter spp. Taken together, our study offers important insights into previously proposed physical models regarding microbial conductivities as well as EET pathways for Shewanella and Geobacter spp.
- Published
- 2016
37. Multicellular Self-Organization of P. aeruginosa due to Interactions with Secreted Trails
- Author
-
W. T. Kranz, Gerard C. L. Wong, Calvin K. Lee, Anatolij Gelimson, Ramin Golestanian, and Kun Zhao
- Subjects
0301 basic medicine ,Movement ,FOS: Physical sciences ,General Physics and Astronomy ,Motility ,Condensed Matter - Soft Condensed Matter ,01 natural sciences ,Pilus ,03 medical and health sciences ,Orientation ,Cell Behavior (q-bio.CB) ,0103 physical sciences ,Physics - Biological Physics ,Quantitative Biology - Populations and Evolution ,010306 general physics ,Probability ,Self-organization ,Chemistry ,Populations and Evolution (q-bio.PE) ,Multicellular organism ,030104 developmental biology ,Biological Physics (physics.bio-ph) ,FOS: Biological sciences ,Fimbriae, Bacterial ,Pseudomonas aeruginosa ,Biophysics ,Quantitative Biology - Cell Behavior ,Soft Condensed Matter (cond-mat.soft) - Abstract
Guided movement in response to slowly diffusing polymeric trails provides a unique mechanism for self-organization of some microorganisms. To elucidate how this signaling route leads to microcolony formation, we experimentally probe the trajectory and orientation of Pseudomonas aeruginosa that propel themselves on a surface using type IV pili motility appendages, which preferentially attach to deposited exopolysaccharides. We construct a stochastic model by analyzing single-bacterium trajectories, and show that the resulting theoretical prediction for the many-body behavior of the bacteria is in quantitative agreement with our experimental characterization of how cells explore the surface via a power law strategy., Comment: 10 pages
- Published
- 2016
38. Evolution of Cell Size Homeostasis and Growth Rate Diversity during Initial Surface Colonization of Shewanella oneidensis
- Author
-
Kenneth H. Nealson, Yujie Chen, Alexander J. Kim, Jaime de Anda, Thomas D. Young, Annette R. Rowe, Paul S. Weiss, David F. Qiao, Stella Y. Lee, Calvin K. Lee, Gerard C. L. Wong, Giancarlo Santiago Santos, and Peter Y. Lai
- Subjects
0301 basic medicine ,030106 microbiology ,Population ,Cell ,bacteria microscopy ,Microbial metabolism ,General Physics and Astronomy ,bacterial appendages ,Microbiology ,03 medical and health sciences ,Extracellular ,medicine ,General Materials Science ,Growth rate ,Shewanella oneidensis ,Nanoscience & Nanotechnology ,education ,bacteria biofilm communities ,education.field_of_study ,biology ,General Engineering ,Biofilm ,single-cell tracking ,cell size homeostasis ,biology.organism_classification ,Cell biology ,medicine.anatomical_structure ,Energy source - Abstract
Cell size control and homeostasis are fundamental features of bacterial metabolism. Recent work suggests that cells add a constant size between birth and division ("adder" model). However, it is not known how cell size homeostasis is influenced by the existence of heterogeneous microenvironments, such as those during biofilm formation. Shewanella oneidensis MR-1 can use diverse energy sources on a range of surfaces via extracellular electron transport (EET), which can impact growth, metabolism, and size diversity. Here, we track bacterial surface communities at single-cell resolution to show that not only do bacterial motility appendages influence the transition from two- to three-dimensional biofilm growth and control postdivisional cell fates, they strongly impact cell size homeostasis. For every generation, we find that the average growth rate for cells that stay on the surface and continue to divide (nondetaching population) and that for cells that detach before their next division (detaching population) are roughly constant. However, the growth rate distribution is narrow for the nondetaching population, but broad for the detaching population in each generation. Interestingly, the appendage deletion mutants (ΔpilA, ΔmshA-D, Δflg) have significantly broader growth rate distributions than that of the wild type for both detaching and nondetaching populations, which suggests that Shewanella appendages are important for sensing and integrating environmental inputs that contribute to size homeostasis. Moreover, our results suggest multiplexing of appendages for sensing and motility functions contributes to cell size dysregulation. These results can potentially provide a framework for generating metabolic diversity in S. oneidensis populations to optimize EET in heterogeneous environments.
- Published
- 2016
39. A review of immune amplification via ligand clustering by self-assembled liquid-crystalline DNA complexes
- Author
-
Roberto Lande, Nathan W. Schmidt, Fan Jin, Ernest Y. Lee, Calvin K. Lee, Gerard C. L. Wong, Michel Gilliet, Daan Frenkel, Jure Dobnikar, and Tine Curk
- Subjects
0301 basic medicine ,Peptide ,01 natural sciences ,Article ,Self assembled ,Autoimmune Diseases ,03 medical and health sciences ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Immune system ,0103 physical sciences ,medicine ,Animals ,Humans ,Physical and Theoretical Chemistry ,010306 general physics ,chemistry.chemical_classification ,Immunity, Cellular ,Systemic lupus erythematosus ,Liquid crystalline ,Surfaces and Interfaces ,DNA ,Dendritic Cells ,medicine.disease ,Cell biology ,Interferon production ,030104 developmental biology ,chemistry ,Interferon Type I ,Ligand clustering - Abstract
We examine how the interferon production of plasmacytoid dendritic cells is amplified by the self-assembly of liquid-crystalline antimicrobial peptide/DNA complexes. These specialized dendritic cells are important for host defense because they quickly release large quantities of type I interferons in response to infection. However, their aberrant activation is also correlated with autoimmune diseases such as psoriasis and lupus. In this review, we will describe how polyelectrolyte self-assembly and the statistical mechanics of multivalent interactions contribute to this process. In a more general compass, we provide an interesting conceptual corrective to the common notion in molecular biology of a dichotomy between specific interactions and non-specific interactions, and show examples where one can construct exquisitely specific interactions using non-specific interactions.
- Published
- 2015
40. Liquid-crystalline ordering of antimicrobial peptide-DNA complexes controls TLR9 activation
- Author
-
Roberto Lande, Tine Curk, Jure Dobnikar, Daniel Frenkel, Wujing Xian, Fan Jin, Calvin K. Lee, Loredana Frasca, Michel Gilliet, Gerard C. L. Wong, and Nathan W. Schmidt
- Subjects
Antimicrobial peptides ,Static Electricity ,Oligonucleotides ,Alpha interferon ,Peptide ,Nanotechnology ,02 engineering and technology ,Endosomes ,03 medical and health sciences ,chemistry.chemical_compound ,Interferon ,Cathelicidins ,medicine ,Humans ,Scattering, Radiation ,General Materials Science ,Computer Simulation ,030304 developmental biology ,chemistry.chemical_classification ,0303 health sciences ,Oligonucleotide ,Mechanical Engineering ,X-Rays ,Interferon-alpha ,hemic and immune systems ,General Chemistry ,DNA ,Dendritic Cells ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Toll-Like Receptor 9 ,Liquid Crystals ,chemistry ,Mechanics of Materials ,Interferon Type I ,Biophysics ,CpG Islands ,0210 nano-technology ,Crystallization ,Monte Carlo Method ,Interferon type I ,medicine.drug ,Antimicrobial Cationic Peptides - Abstract
Double stranded DNA (dsDNA) can trigger the production of type I interferon (IFN) in plasmacytoid dendritic cells (pDCs) by binding to endosomal Toll like receptor 9 (TLR9; refs 1 2 3 4 5). It is also known that the formation of DNA–antimicrobial peptide complexes can lead to autoimmune diseases via amplification of pDC activation1 2. Here by combining X ray scattering computer simulations microscopy and measurements of pDC IFN production we demonstrate that a broad range of antimicrobial peptides and other cationic molecules cause similar effects and elucidate the criteria for amplification. TLR9 activation depends on both the inter DNA spacing and the multiplicity of parallel DNA ligands in the self assembled liquid crystalline complex. Complexes with a grill like arrangement of DNA at the optimum spacing can interlock with multiple TLR9 like a zipper leading to multivalent electrostatic interactions that drastically amplify binding and thereby the immune response. Our results suggest that TLR9 activation and thus TLR9 mediated immune responses can be modulated deterministically.
- Published
- 2014
41. Species-dependent hydrodynamics of flagellum-tethered bacteria in early biofilm development
- Author
-
Kenneth H. Nealson, Gerard C. L. Wong, George A. O'Toole, Fitnat H. Yildiz, Calvin K. Lee, Jaime de Anda, Ramin Golestanian, and Rachel R. Bennett
- Subjects
0301 basic medicine ,Shewanella ,Biomedical Engineering ,Biophysics ,Motility ,Bioengineering ,Biology ,Flagellum ,medicine.disease_cause ,Flagellar filament ,01 natural sciences ,Biochemistry ,Bacterial Adhesion ,Bacterial cell structure ,Microbiology ,Biomaterials ,03 medical and health sciences ,Species Specificity ,0103 physical sciences ,medicine ,Shewanella oneidensis ,010306 general physics ,Vibrio cholerae ,Biofilm ,Life Sciences–Physics interface ,biology.organism_classification ,030104 developmental biology ,Flagella ,Biofilms ,Pseudomonas aeruginosa ,Hydrodynamics ,Bacteria ,Biotechnology - Abstract
Monotrichous bacteria on surfaces exhibit complex spinning movements. Such spinning motility is often a part of the surface detachment launch sequence of these cells. To understand the impact of spinning motility on bacterial surface interactions, we develop a hydrodynamic model of a surface-bound bacterium, which reproduces behaviours that we observe in Pseudomonas aeruginosa , Shewanella oneidensis and Vibrio cholerae , and provides a detailed dictionary for connecting observed spinning behaviour to bacteria–surface interactions. Our findings indicate that the fraction of the flagellar filament adhered to the surface, the rotation torque of this appendage, the flexibility of the flagellar hook and the shape of the bacterial cell dictate the likelihood that a microbe will detach and the optimum orientation that it should have during detachment. These findings are important for understanding species-specific reversible attachment, the key transition event between the planktonic and biofilm lifestyle for motile, rod-shaped organisms.
- Published
- 2016
42. Three-wavelength light transmission technique to measure smoke particle size and concentration
- Author
-
Calvin K. Lee, Kenneth L. Cashdollar, and Joseph M. Singer
- Subjects
Smoke ,Materials science ,genetic structures ,business.industry ,Materials Science (miscellaneous) ,Mie scattering ,Instrumentation ,Physics::Optics ,Industrial and Manufacturing Engineering ,Wavelength ,Optics ,Extinction (optical mineralogy) ,Mass concentration (chemistry) ,sense organs ,Particle size ,Business and International Management ,business ,Refractive index - Abstract
This paper describes an optical technique and instrumentation for measuring the average particle size and mass concentration of smoke. Transmission through the smoke at three wavelengths (0.45 microm, 0.63 microm, and 1.00 microm) is measured using a white light source and a compact, three-wavelength detector assembly. Sizes and concentrations are then calculated from the transmission data using Mie theory. Graphs of the calculated Mie extinction coefficients are presented for several complex refractive indices. This three-wavelength optical technique was used to study smoke from a wood-tunnel fire, and the results are compared to those of other sizing techniques.
- Published
- 2010
43. Coal Pyrolysis at Fire-Level Heat Flux
- Author
-
Robert F. Chaiken, Calvin K. Lee, and Joseph M. Singer
- Subjects
Exothermic reaction ,Chemistry ,business.industry ,General Chemical Engineering ,technology, industry, and agriculture ,Energy value of coal ,General Physics and Astronomy ,Energy Engineering and Power Technology ,General Chemistry ,Coke ,Dry distillation ,complex mixtures ,Endothermic process ,respiratory tract diseases ,Fuel Technology ,Heat flux ,Chemical engineering ,otorhinolaryngologic diseases ,Coal ,business ,Pyrolysis - Abstract
Pyrolysis of Pittsburgh Seam coal at fire-level surface heat fluxes of 0.76 and 2.0 cal/cm2-sec was investigated by means of measurements of mass-loss rate, density, temperature and internal gas pressure of pyrolyzing coal and thermal properties of coal and coke. Local and overall heats of pyrolysis were determined from these measurements at 2.0 cal/cm2-sec. It was found that as coal pyrolyzes, a surface coke layer (580 °C
- Published
- 1977
44. Burning rate of fuel cylinders
- Author
-
Calvin K. Lee
- Subjects
Chemistry ,General Chemical Engineering ,Analytical chemistry ,Grashof number ,General Physics and Astronomy ,Energy Engineering and Power Technology ,General Chemistry ,Mechanics ,Radius ,Solid fuel ,Cylinder (engine) ,law.invention ,Physics::Fluid Dynamics ,Fuel mass fraction ,Fuel Technology ,law ,Phase (matter) ,Thermal ,Physics::Chemical Physics ,Physics::Atmospheric and Oceanic Physics - Abstract
The mass burning rate of a horizontal fuel cylinder at low Grashof numbers is analyzed using a semiempirical method. The method consists of utilizing the Schvab-Zeldovich formulation with a flame-sheet model and measured flame standoff distances. The derived burning rate expressed in terms of the thermal properties of the solid fuel and the gaseous phase, and the cylinder radius show general agreement with experiment.
- Published
- 1978
45. Smoke characteristics of coal-lined tunnel fires
- Author
-
Kenneth L. Cashdollar, Charles D. Litton, Calvin K. Lee, and Joseph M. Singer
- Subjects
Smoke ,Polymers and Plastics ,business.industry ,Metals and Alloys ,Environmental engineering ,Poison control ,General Chemistry ,Particulates ,complex mixtures ,Electronic, Optical and Magnetic Materials ,Mining engineering ,Fire protection ,Particle diameter ,Ceramics and Composites ,Mass concentration (chemistry) ,Particle ,Environmental science ,Coal ,business - Abstract
Characteristics of smoke particulates generated from a coal fire in a ventilated model tunnel were investigated by laser optical transmission and by electron microscopy. Average particle diameter and mass concentration of the smoke were determined as a function of the temperature and stoichimoetry of the coal tunnel fire. Smoke particle sizes ranged from 0.2 to 0.9 μm, with larger particle sizes associated with higher smoke concentrations. These coal smoke data are relevant to several aspects of underground mine safety including the development and location of smoke detection instruments, the understanding of the fire (toxic fume) hazard, and the development of new fire protection and control techniques.
- Published
- 1981
46. Combustion of irradiated dry and wet oak
- Author
-
J.Rodney Diehl and Calvin K. Lee
- Subjects
General Chemical Engineering ,General Physics and Astronomy ,Energy Engineering and Power Technology ,chemistry.chemical_element ,General Chemistry ,Combustion ,Fuel Technology ,chemistry ,Environmental chemistry ,Green wood ,Char ,Gas composition ,Carbon ,Water content ,Pyrolysis ,Water vapor - Abstract
Combustion of dry oak and wet oak with 50 wt% water content at a fire level surface heat flux of 2 cal/cm2 sec was experimentally investigated. Experimental measurements included thermal-physical properties, mass loss rate, surface regression rate, solid density, temperature, pressure, and gas composition. Effects of absorbed water on wood pyrolysis and combustion are examined from these measurements. It is found that the absorbed water mainly delays the temperature rise in the wet wood and the vaporized water convectively cools the pyrolyzing wood. The pyrolysis process is thus delayed in the wet wood and the volatile combustible gases are diluted by the water vapor. Decomposition of water and reaction between water and wood char (carbon) do not appear to occur significantly. At steady-state burning, surface regression rates are the same for both dry and wet wood, apparently because the regression rate is primarily governed by the oxygen supply to the char surface.
- Published
- 1981
47. Smoke characteristics of tunnel wood fires
- Author
-
Calvin K. Lee, Joseph M. Singer, and Kenneth L. Cashdollar
- Subjects
Smoke ,Polymers and Plastics ,Smoke testing (mechanical) ,Metals and Alloys ,Environmental engineering ,Poison control ,Exhaust gas ,General Chemistry ,Particulates ,Atmospheric sciences ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Ceramics and Composites ,Mass concentration (chemistry) ,Environmental science ,Current (fluid) ,Carbon monoxide - Abstract
Characteristics of smoke particulates generated from a wood fire in a ventilated model tunnel were investigated using an in situ optical and a grid sampling technique. Volume-to-surface mean diameter and mass concentration of the smoke particles, and the transmission, optical density per unit length and particulate optical density of the smokeladen exhaust gas were obtained as a function of the burning process in the tunnel. It was found that high concentration of smoke (∼1 mg l−1) were rapidly generated as the fire changed from oxygen-rich to fuel-rich burning, resulting in fast obscuration of the passageway. The simultaneous generationof large amounts of smoke and high temperature carbon monoxide (∼8%) coupled with low transmission (∼1% though 0.5 m) represents and extremely hazardous situation in such a fire environment. Present measurements and others from current smoke testing chambers are compared and discussed.
- Published
- 1978
48. Interaction Between Duct Fires and Ventilation Flow: An Experimental Study
- Author
-
Joseph M. Singer, Calvin K. Lee, and Robert F. Chaiken
- Subjects
Air velocity ,Flow resistance ,Meteorology ,General Chemical Engineering ,General Physics and Astronomy ,Energy Engineering and Power Technology ,General Chemistry ,Mechanics ,Bandwidth throttling ,Combustion ,symbols.namesake ,Fuel Technology ,Froude number ,symbols ,Mass flow rate ,Environmental science ,Duct (flow) - Abstract
The influence of wood fires in a 0·3 ×0·3 × 10 m duct on forced ventilation flow was studied in a model tunnel network by measuring tunnel gas mass flow rate, velocity, pressure, and temperature. Comparison of these measurements obtained before and during the fires at various ventilation air velocities provides useful information on the interaction between duct fires and ventilation flow in terms of fire throttling effects and reverse flow phenomena. Results show that duct fires essentially increase flow resistances of the passageways of a tunnel network by virtue of volatile fuel mass injection and high combustion temperatures. In the present tunnel network, the flow resistance in the fire zone was increased by a factor of 6, and upstream and downstream of the fire by ∼1·5. The ventilation air velocity was thus throttled to less than half of its initial value before the fire. Reverse flow occurred when the throttled air velocity was ∼0·6 m/s, which corresponds to a Froude number of ∼7 (based on ...
- Published
- 1979
49. Charring pyrolysis of wood in fires by laser simulation
- Author
-
Robert F. Chaiken, Joseph M. Singer, and Calvin K. Lee
- Subjects
Materials science ,Heat flux ,Thermal ,Charring ,Radiation ,Composite material ,Wood grain ,Pyrolysis ,Endothermic process ,Decomposition - Abstract
Utilizing a 250 watt CO2-laser radiation source, wood pyrolysis at fire-level surface heat flux was investigated through the measurement of decomposition rates, solid temperatures and thermal properties, pyrolysis gas compositions and pressures, and crack formation. Heats of reaction calculated from these measurements show that at an incident heat flux of 0.76 cal/cm2-sec applied parallel to the wood grain direction, the pyrolysis layer (≈1cm thick) can be divided into three zones: (i) an endothermic primary decomposition zone at temperatures T
- Published
- 1977
50. Estimates of luminous flame radiation from fires
- Author
-
Calvin K. Lee
- Subjects
chemistry.chemical_classification ,SIMPLE (dark matter experiment) ,Materials science ,business.industry ,General Chemical Engineering ,General Physics and Astronomy ,Energy Engineering and Power Technology ,Luminous flame ,General Chemistry ,Radiation ,Adiabatic flame temperature ,Physics::Fluid Dynamics ,Condensed Matter::Soft Condensed Matter ,Fuel Technology ,Optics ,Hydrocarbon ,chemistry ,Thermal radiation ,Beam length ,Physics::Chemical Physics ,Atomic physics ,Soot particles ,business - Abstract
Luminous radiation from the soot particles of a flame propagating vertically downward on a polymethyl methacrylate (PMMA) rod is investigated by using exact and approximate analyses. Investigation shows that for vertically downward burning of a 0.5 in. diam PMMA rod, the luminous radiative heat transfer from the flame to the fuel rod is well within the optically thin limit. The approximate analysis is extended to conventional hydrocarbon fuels. A simple optically thin approximation in terms of flame temperature T f and mean beam length L m is obtained for the luminous radiation from soot particles. The thin approximation gives errors of less than 5% from exact values for L m T f
- Published
- 1975
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