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Kim J, Lee SJ. Digital in-line holographic microscopy for label-free identification and tracking of biological cells. Mil Med Res 2024; 11:38. [PMID: 38867274 PMCID: PMC11170804 DOI: 10.1186/s40779-024-00541-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 05/31/2024] [Indexed: 06/14/2024] Open
Abstract
Digital in-line holographic microscopy (DIHM) is a non-invasive, real-time, label-free technique that captures three-dimensional (3D) positional, orientational, and morphological information from digital holographic images of living biological cells. Unlike conventional microscopies, the DIHM technique enables precise measurements of dynamic behaviors exhibited by living cells within a 3D volume. This review outlines the fundamental principles and comprehensive digital image processing procedures employed in DIHM-based cell tracking methods. In addition, recent applications of DIHM technique for label-free identification and digital tracking of various motile biological cells, including human blood cells, spermatozoa, diseased cells, and unicellular microorganisms, are thoroughly examined. Leveraging artificial intelligence has significantly enhanced both the speed and accuracy of digital image processing for cell tracking and identification. The quantitative data on cell morphology and dynamics captured by DIHM can effectively elucidate the underlying mechanisms governing various microbial behaviors and contribute to the accumulation of diagnostic databases and the development of clinical treatments.
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Affiliation(s)
- Jihwan Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, 37673, Republic of Korea
| | - Sang Joon Lee
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk, 37673, Republic of Korea.
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Matthews SA, Coelho C, Rodriguez Salas EE, Brock EE, Hodge VJ, Walker JA, Wilson LG. Real-time 3D tracking of swimming microbes using digital holographic microscopy and deep learning. PLoS One 2024; 19:e0301182. [PMID: 38669245 PMCID: PMC11051601 DOI: 10.1371/journal.pone.0301182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/12/2024] [Indexed: 04/28/2024] Open
Abstract
The three-dimensional swimming tracks of motile microorganisms can be used to identify their species, which holds promise for the rapid identification of bacterial pathogens. The tracks also provide detailed information on the cells' responses to external stimuli such as chemical gradients and physical objects. Digital holographic microscopy (DHM) is a well-established, but computationally intensive method for obtaining three-dimensional cell tracks from video microscopy data. We demonstrate that a common neural network (NN) accelerates the analysis of holographic data by an order of magnitude, enabling its use on single-board computers and in real time. We establish a heuristic relationship between the distance of a cell from the focal plane and the size of the bounding box assigned to it by the NN, allowing us to rapidly localise cells in three dimensions as they swim. This technique opens the possibility of providing real-time feedback in experiments, for example by monitoring and adapting the supply of nutrients to a microbial bioreactor in response to changes in the swimming phenotype of microbes, or for rapid identification of bacterial pathogens in drinking water or clinical samples.
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Affiliation(s)
- Samuel A. Matthews
- School of Physics, Engineering and Technology, University of York, Heslington, York, United Kingdom
| | - Carlos Coelho
- School of Physics, Engineering and Technology, University of York, Heslington, York, United Kingdom
| | - Erick E. Rodriguez Salas
- School of Physics, Engineering and Technology, University of York, Heslington, York, United Kingdom
| | - Emma E. Brock
- School of Physics, Engineering and Technology, University of York, Heslington, York, United Kingdom
| | | | - James A. Walker
- Department of Computer Science, Deramore Lane, York, United Kingdom
| | - Laurence G. Wilson
- School of Physics, Engineering and Technology, University of York, Heslington, York, United Kingdom
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Johnston N, Dubay MM, Serabyn E, Nadeau JL. Detectability of unresolved particles in off-axis digital holographic microscopy. APPLIED OPTICS 2024; 63:B114-B125. [PMID: 38437262 DOI: 10.1364/ao.507375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 01/09/2024] [Indexed: 03/06/2024]
Abstract
Off-axis digital holographic microscopy (DHM) provides both amplitude and phase images, and so it may be used for label-free 3D tracking of micro- and nano-sized particles of different compositions, including biological cells, strongly absorbing particles, and strongly scattering particles. Contrast is provided by differences in either the real or imaginary parts of the refractive index (phase contrast and absorption) and/or by scattering. While numerous studies have focused on phase contrast and improving resolution in DHM, particularly axial resolution, absent have been studies quantifying the limits of detection for unresolved particles. This limit has important implications for microbial detection, including in life-detection missions for space flight. Here we examine the limits of detection of nanosized particles as a function of particle optical properties, microscope optics (including camera well depth and substrate), and data processing techniques and find that DHM provides contrast in both amplitude and phase for unresolved spheres, in rough agreement with Mie theory scattering cross-sections. Amplitude reconstructions are more useful than phase for low-index spheres and should not be neglected in DHM analysis.
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Snyder C, Centlivre JP, Bhute S, Shipman G, Friel AD, Viver T, Palmer M, Konstantinidis KT, Sun HJ, Rossello-Mora R, Nadeau J, Hedlund BP. Microbial Motility at the Bottom of North America: Digital Holographic Microscopy and Genomic Motility Signatures in Badwater Spring, Death Valley National Park. ASTROBIOLOGY 2023; 23:295-307. [PMID: 36625891 DOI: 10.1089/ast.2022.0090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Motility is widely distributed across the tree of life and can be recognized by microscopy regardless of phylogenetic affiliation, biochemical composition, or mechanism. Microscopy has thus been proposed as a potential tool for detection of biosignatures for extraterrestrial life; however, traditional light microscopy is poorly suited for this purpose, as it requires sample preparation, involves fragile moving parts, and has a limited volume of view. In this study, we deployed a field-portable digital holographic microscope (DHM) to explore microbial motility in Badwater Spring, a saline spring in Death Valley National Park, and complemented DHM imaging with 16S rRNA gene amplicon sequencing and shotgun metagenomics. The DHM identified diverse morphologies and distinguished run-reverse-flick and run-reverse types of flagellar motility. PICRUSt2- and literature-based predictions based on 16S rRNA gene amplicons were used to predict motility genotypes/phenotypes for 36.0-60.1% of identified taxa, with the predicted motile taxa being dominated by members of Burkholderiaceae and Spirochaetota. A shotgun metagenome confirmed the abundance of genes encoding flagellar motility, and a Ralstonia metagenome-assembled genome encoded a full flagellar gene cluster. This study demonstrates the potential of DHM for planetary life detection, presents the first microbial census of Badwater Spring and brine pool, and confirms the abundance of mobile microbial taxa in an extreme environment.
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Affiliation(s)
- Carl Snyder
- Department of Physics, Portland State University, Portland, Oregon, USA
| | - Jakob P Centlivre
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Shrikant Bhute
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Gözde Shipman
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Ariel D Friel
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Tomeu Viver
- Marine Microbiology Group, Department of Animal and Microbial Biodiversity, Mediterranean Institute for Advanced Studies (CSIC-UIB), Esporles, Illes Balears, Spain
| | - Marike Palmer
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | | | - Henry J Sun
- Desert Research Institute, Las Vegas, Nevada, USA
| | - Ramon Rossello-Mora
- Marine Microbiology Group, Department of Animal and Microbial Biodiversity, Mediterranean Institute for Advanced Studies (CSIC-UIB), Esporles, Illes Balears, Spain
| | - Jay Nadeau
- Department of Physics, Portland State University, Portland, Oregon, USA
| | - Brian P Hedlund
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
- Nevada Institute of Personalized Medicine, Las Vegas, Nevada, USA
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Dubay MM, Acres J, Riekeles M, Nadeau JL. Recent advances in experimental design and data analysis to characterize prokaryotic motility. J Microbiol Methods 2023; 204:106658. [PMID: 36529156 DOI: 10.1016/j.mimet.2022.106658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/13/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Bacterial motility plays a key role in important cell processes such as chemotaxis and biofilm formation, but is challenging to quantify due to the small size of the individual microorganisms and the complex interplay of biological and physical factors that influence motility phenotypes. Swimming, the first type of motility described in bacteria, still remains largely unquantified. Light microscopy has enabled qualitative characterization of swimming patterns seen in different strains, such as run and tumble, run-reverse-flick, run and slow, stop and coil, and push and pull, which has allowed for elucidation of the underlying physics. However, quantifying these behaviors (e.g., identifying run distances and speeds, turn angles and behavior by surfaces or cell-cell interactions) remains a challenging task. A qualitative and quantitative understanding of bacterial motility is needed to bridge the gap between experimentation, omics analysis, and bacterial motility theory. In this review, we discuss the strengths and limitations of how phase contrast microscopy, fluorescence microscopy, and digital holographic microscopy have been used to quantify bacterial motility. Approaches to automated software analysis, including cell recognition, tracking, and track analysis, are also discussed with a view to providing a guide for experimenters to setting up the appropriate imaging and analysis system for their needs.
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Affiliation(s)
- Megan Marie Dubay
- Department of Physics, Portland State University, 1719 SW 10(th) Ave., Portland, OR 97201, United States of America
| | - Jacqueline Acres
- Department of Physics, Portland State University, 1719 SW 10(th) Ave., Portland, OR 97201, United States of America
| | - Max Riekeles
- Astrobiology Group, Center of Astronomy and Astrophysics, Technical University Berlin, Hardenbergstraße 36A, 10623 Berlin, Germany
| | - Jay L Nadeau
- Department of Physics, Portland State University, 1719 SW 10(th) Ave., Portland, OR 97201, United States of America.
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Rouzie D, Lindensmith C, Nadeau J. Microscopic Object Classification through Passive Motion Observations with Holographic Microscopy. Life (Basel) 2021; 11:life11080793. [PMID: 34440537 PMCID: PMC8401815 DOI: 10.3390/life11080793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/31/2021] [Accepted: 08/01/2021] [Indexed: 11/16/2022] Open
Abstract
Digital holographic microscopy provides the ability to observe throughout a volume that is large compared to its resolution without the need to actively refocus to capture the entire volume. This enables simultaneous observations of large numbers of small objects within such a volume. We have constructed a microscope that can observe a volume of 0.4 µm × 0.4 µm × 1.0 µm with submicrometer resolution (in xy) and 2 µm resolution (in z) for observation of microorganisms and minerals in liquid environments on Earth and on potential planetary missions. Because environmental samples are likely to contain mixtures of inorganics and microorganisms of comparable sizes near the resolution limit of the instrument, discrimination between living and non-living objects may be difficult. The active motion of motile organisms can be used to readily distinguish them from non-motile objects (live or inorganic), but additional methods are required to distinguish non-motile organisms and inorganic objects that are of comparable size but different composition and structure. We demonstrate the use of passive motion to make this discrimination by evaluating diffusion and buoyancy characteristics of cells, styrene beads, alumina particles, and gas-filled vesicles of micron scale in the field of view.
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Affiliation(s)
- Devan Rouzie
- Department of Physics, Portland State University, 1719 SW 10th Ave., Portland, OR 97201, USA;
| | - Christian Lindensmith
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91125, USA;
| | - Jay Nadeau
- Department of Physics, Portland State University, 1719 SW 10th Ave., Portland, OR 97201, USA;
- Correspondence: ; Tel.: +1-503-795-8929
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Findlay RC, Osman M, Spence KA, Kaye PM, Walrad PB, Wilson LG. High-speed, three-dimensional imaging reveals chemotactic behaviour specific to human-infective Leishmania parasites. eLife 2021; 10:65051. [PMID: 34180835 PMCID: PMC8238501 DOI: 10.7554/elife.65051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 06/08/2021] [Indexed: 12/04/2022] Open
Abstract
Cellular motility is an ancient eukaryotic trait, ubiquitous across phyla with roles in predator avoidance, resource access, and competition. Flagellar motility is seen in various parasitic protozoans, and morphological changes in flagella during the parasite life cycle have been observed. We studied the impact of these changes on motility across life cycle stages, and how such changes might serve to facilitate human infection. We used holographic microscopy to image swimming cells of different Leishmania mexicana life cycle stages in three dimensions. We find that the human-infective (metacyclic promastigote) forms display ‘run and tumble’ behaviour in the absence of stimulus, reminiscent of bacterial motion, and that they specifically modify swimming direction and speed to target host immune cells in response to a macrophage-derived stimulus. Non-infective (procyclic promastigote) cells swim more slowly, along meandering helical paths. These findings demonstrate adaptation of swimming phenotype and chemotaxis towards human cells.
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Affiliation(s)
- Rachel C Findlay
- York Biomedical Research Institute, Department of Biology, University of York, York, United Kingdom.,Department of Physics, University of York, York, United Kingdom
| | - Mohamed Osman
- York Biomedical Research Institute, Hull York Medical School, University of York, York, United Kingdom
| | - Kirstin A Spence
- York Biomedical Research Institute, Department of Biology, University of York, York, United Kingdom
| | - Paul M Kaye
- York Biomedical Research Institute, Hull York Medical School, University of York, York, United Kingdom
| | - Pegine B Walrad
- York Biomedical Research Institute, Department of Biology, University of York, York, United Kingdom
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