1
|
Meldrum OW, Yakubov GE. Journey of dietary fiber along the gastrointestinal tract: role of physical interactions, mucus, and biochemical transformations. Crit Rev Food Sci Nutr 2024:1-29. [PMID: 39141568 DOI: 10.1080/10408398.2024.2390556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
Dietary fiber-rich foods have been associated with numerous health benefits, including a reduced risk of cardiovascular and metabolic diseases. Harnessing the potential to deliver positive health outcomes rests on our understanding of the underlying mechanisms that drive these associations. This review addresses data and concepts concerning plant-based food functionality by dissecting the cascade of physical and chemical digestive processes and interactions that underpin these physiological benefits. Functional transformations of dietary fiber along the gastrointestinal tract from the stages of oral processing and gastric emptying to intestinal digestion and colonic fermentation influence its capacity to modulate digestion, transit, and commensal microbiome. This analysis highlights the significance, limitations, and challenges in decoding the complex web of interactions to establish a coherent framework connecting specific fiber components' molecular and macroscale interactions across multiple length scales within the gastrointestinal tract. One critical area that requires closer examination is the interaction between fiber, mucus barrier, and the commensal microbiome when considering food structure design and personalized nutritional strategies for beneficial physiologic effects. Understanding the response of specific fibers, particularly concerning an individual's physiology, will offer the opportunity to exploit these functional characteristics to elicit specific, symptom-targeting effects or use fiber types as adjunctive therapies.
Collapse
Affiliation(s)
- Oliver W Meldrum
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Gleb E Yakubov
- Soft Matter Biomaterials and Biointerfaces, School of Biosciences, University of Nottingham, Nottingham, UK
| |
Collapse
|
2
|
Su-Arcaro C, Liao W, Bieniek K, Constantino MA, Decker SM, Turner BS, Bansil R. Unraveling the Intertwined Effect of pH on Helicobacter pylori Motility and the Microrheology of the Mucin-Based Medium It Swims in. Microorganisms 2023; 11:2745. [PMID: 38004756 PMCID: PMC10673263 DOI: 10.3390/microorganisms11112745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/16/2023] [Accepted: 11/03/2023] [Indexed: 11/26/2023] Open
Abstract
The gastric pathogen, Helicobacter pylori bacteria have to swim across a pH gradient from 2 to 7 in the mucus layer to colonize the gastric epithelium. Previous studies from our group have shown that porcine gastric mucin (PGM) gels at an acidic pH < 4, and H. pylori bacteria are unable to swim in the gel, although their flagella rotate. Changing pH impacts both the rheological properties of gastric mucin and also influences the proton (H+)-pumped flagellar motors of H. pylori as well as their anti-pH sensing receptors. To unravel these intertwined effects of acidic pH on both the viscoelastic properties of the mucin-based mucus as well as the flagellar motors and chemo-receptors of the bacterium, we compared the motility of H. pylori in PGM with that in Brucella broth (BB10) at different pH values using phase contrast microscopy to track the motion of the bacteria. The results show that the distribution of swimming speeds and other characteristics of the bacteria trajectories exhibit pH-dependent differences in both media. The swimming speed exhibits a peak at pH 4 in BB10, and a less pronounced peak at a higher pH of 5 in PGM. At all pH values, the bacteria swam faster and had a longer net displacement in BB10 compared to PGM. While the bacteria were stuck in PGM gels at pH < 4, they swam at these acidic pH values in BB10, although with reduced speed. Decreasing pH leads to a decreased fraction of motile bacteria, with a decreased contribution of the faster swimmers to the distributions of speeds and net displacement of trajectories. The body rotation rate is weakly dependent on pH in BB10, whereas in PGM bacteria that are immobilized in the low pH gel are capable of mechano-sensing and rotate faster. Bacteria can be stuck in the gel in various ways, including the flagella getting entangled in the fibers of the gel or the cell body being stuck to the gel. Our results show that in BB10, swimming is optimized at pH4, reflecting the combined effects of pH sensing by anti-pH tactic receptors and impact on H+ pumping of flagellar motors, while the increase in viscosity of PGM with decreasing pH and gelation below pH 4 lead to further reduction in swimming speed, with optimal swimming at pH 5 and immobilization of bacteria below pH 4.
Collapse
Affiliation(s)
- Clover Su-Arcaro
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| | - Wentian Liao
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| | - Katarzyna Bieniek
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| | - Maira A. Constantino
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| | - Savannah M. Decker
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| | - Bradley S. Turner
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;
| | - Rama Bansil
- Department of Physics, Boston University, Boston, MA 02215, USA; (C.S.-A.); (W.L.); (K.B.); (M.A.C.); (S.M.D.)
| |
Collapse
|
3
|
Carroll-Portillo A, Rumsey KN, Braun CA, Lin DM, Coffman CN, Alcock JA, Singh SB, Lin HC. Mucin and Agitation Shape Predation of Escherichia coli by Lytic Coliphage. Microorganisms 2023; 11:microorganisms11020508. [PMID: 36838472 PMCID: PMC9966288 DOI: 10.3390/microorganisms11020508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/15/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023] Open
Abstract
The ability of bacteriophage (phage), abundant within the gastrointestinal microbiome, to regulate bacterial populations within the same micro-environment offers prophylactic and therapeutic opportunities. Bacteria and phage have both been shown to interact intimately with mucin, and these interactions invariably effect the outcomes of phage predation within the intestine. To better understand the influence of the gastrointestinal micro-environment on phage predation, we employed enclosed, in vitro systems to investigate the roles of mucin concentration and agitation as a function of phage type and number on bacterial killing. Using two lytic coliphage, T4 and PhiX174, bacterial viability was quantified following exposure to phages at different multiplicities of infection (MOI) within increasing, physiological levels of mucin (0-4%) with and without agitation. Comparison of bacterial viability outcomes demonstrated that at low MOI, agitation in combination with higher mucin concentration (>2%) inhibited phage predation by both phages. However, when MOI was increased, PhiX predation was recovered regardless of mucin concentration or agitation. In contrast, only constant agitation of samples containing a high MOI of T4 demonstrated phage predation; briefly agitated samples remained hindered. Our results demonstrate that each phage-bacteria pairing is uniquely influenced by environmental factors, and these should be considered when determining the potential efficacy of phage predation under homeostatic or therapeutic circumstances.
Collapse
Affiliation(s)
- Amanda Carroll-Portillo
- Division of Gastroenterology and Hepatology, University of New Mexico, Albuquerque, NM 87131, USA
- Correspondence:
| | - Kellin N. Rumsey
- Statistical Sciences, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Cody A. Braun
- Biomedical Research Institute of New Mexico, Albuquerque, NM 87108, USA
| | - Derek M. Lin
- Biomedical Research Institute of New Mexico, Albuquerque, NM 87108, USA
| | | | - Joe A. Alcock
- Department of Emergency Medicine, University of New Mexico, Albuquerque, NM 87131, USA
| | - Sudha B. Singh
- Biomedical Research Institute of New Mexico, Albuquerque, NM 87108, USA
| | - Henry C. Lin
- Division of Gastroenterology and Hepatology, University of New Mexico, Albuquerque, NM 87131, USA
- Medicine Service, New Mexico VA Health Care System, Albuquerque, NM 87108, USA
| |
Collapse
|
4
|
Kakati N, Parashar CK, Thakur S, Deshmukh OS, Bandyopadhyay D. Microrheology of Mucin-Albumin Assembly Using Diffusing Wave Spectroscopy. ACS APPLIED BIO MATERIALS 2022; 5:4118-4127. [PMID: 35969851 DOI: 10.1021/acsabm.2c00098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mucus plays an important role in the protection of the epithelial cells from various pathogens and low pH environments besides helping in the absorption of nutrients. Alteration of the rheology of the mucus layer leads to various disease conditions such as cystic fibrosis, Crohn's disease, and gastric ulcers, among others. Importantly, mucus consists of various mucins along with proteins such as immunoglobulin, lysozyme, and albumin. In the present study, we explore the effect of pH on the interactions between bovine serum albumin (BSA) and porcine gastric mucins using diffusing wave spectroscopy (DWS). The study unveils that BSA actively binds with mucin to form mucin-BSA complexes, which is largely driven by electrostatic interactions. Interestingly, such physical interactions significantly alter the microrheology of these biomaterials, which is indicated by a reduction in the diffusivity of tracer particles in DWS. An array of DWS experiments suggests that the interaction between mucin and BSA is the highest at pH 7.4 and the least at pH 3. Further analyses using atomic force microscopy showed the formation of a compact cross-linked colloidal network of mucin-BSA complexes at pH 7.4, which is the main reason for the reduction in the diffusivity of the tracer particles in DWS. Furthermore, the circular dichroism analysis revealed that the secondary structures of mucin-BSA complexes are markedly different from those of only mucin at pH 7.4. Importantly, such a difference has not been observed at pH 3, which confirms that largely electrostatic interactions drive the formation of mucin-BSA complexes at neutral pH. In such a scenario, the presence of Ca2+ ions is also found to facilitate bridging between BSA molecules, which is also reflected in the microrheology of the suspension of BSA-mucin complexes.
Collapse
Affiliation(s)
- Nayanjyoti Kakati
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | | | - Siddharth Thakur
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Omkar Suresh Deshmukh
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
| | - Dipankar Bandyopadhyay
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, India
| |
Collapse
|
5
|
Radiom M, Hénault R, Mani S, Iankovski AG, Norel X, Berret JF. Magnetic wire active microrheology of human respiratory mucus. SOFT MATTER 2021; 17:7585-7595. [PMID: 34341819 DOI: 10.1039/d1sm00512j] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mucus is a viscoelastic gel secreted by the pulmonary epithelium in the tracheobronchial region of the lungs. The coordinated beating of cilia moves mucus upwards towards the pharynx, removing inhaled pathogens and particles from the airways. The efficacy of this clearance mechanism depends primarily on the rheological properties of mucus. Here we use magnetic wire based microrheology to study the viscoelastic properties of human mucus collected from human bronchus tubes. The response of wires between 5 and 80 μm in length to a rotating magnetic field is monitored by optical time-lapse microscopy and analyzed using constitutive equations of rheology, including those of Maxwell and Kelvin-Voigt. The static shear viscosity and elastic modulus can be inferred from low frequency (3 × 10-3-30 rad s-1) measurements, leading to the evaluation of the mucin network relaxation time. This relaxation time is found to be widely distributed, from one to several hundred seconds. Mucus is identified as a viscoelastic liquid with an elastic modulus of 2.5 ± 0.5 Pa and a static viscosity of 100 ± 40 Pa s. Our work shows that beyond the established spatial variations in rheological properties due to microcavities, mucus exhibits secondary inhomogeneities associated with the relaxation time of the mucin network that may be important for its flow properties.
Collapse
Affiliation(s)
- Milad Radiom
- Université de Paris, CNRS, Matière et Systèmes Complexes, 75013 Paris, France.
| | | | | | | | | | | |
Collapse
|
6
|
Nanomechanical Hallmarks of Helicobacter pylori Infection in Pediatric Patients. Int J Mol Sci 2021; 22:ijms22115624. [PMID: 34070700 PMCID: PMC8198391 DOI: 10.3390/ijms22115624] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/22/2021] [Accepted: 05/24/2021] [Indexed: 12/24/2022] Open
Abstract
Background: the molecular mechanism of gastric cancer development related to Helicobacter pylori (H. pylori) infection has not been fully understood, and further studies are still needed. Information regarding nanomechanical aspects of pathophysiological events that occur during H. pylori infection can be crucial in the development of new prevention, treatment, and diagnostic measures against clinical consequences associated with H. pylori infection, including gastric ulcer, duodenal ulcer, and gastric cancer. Methods: in this study, we assessed mechanical properties of children’s healthy and H. pylori positive stomach tissues and the mechanical response of human gastric cells exposed to heat-treated H. pylori cells using atomic force microscopy (AFM NanoWizard 4 BioScience JPK Instruments Bruker). Elastic modulus (i.e., the Young’s modulus) was derived from the Hertz–Sneddon model applied to force-indentation curves. Human tissue samples were evaluated using rapid urease tests to identify H. pylori positive samples, and the presence of H. pylori cells in those samples was confirmed using immunohistopathological staining. Results and conclusion: collected data suggest that nanomechanical properties of infected tissue might be considered as markers indicated H. pylori presence since infected tissues are softer than uninfected ones. At the cellular level, this mechanical response is at least partially mediated by cell cytoskeleton remodeling indicating that gastric cells are able to tune their mechanical properties when subjected to the presence of H. pylori products. Persistent fluctuations of tissue mechanical properties in response to H. pylori infection might, in the long-term, promote induction of cancer development.
Collapse
|
7
|
Wang Z, Wang X, Zhang Y, Xu W, Han X. Principles and Applications of Single Particle Tracking in Cell Research. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005133. [PMID: 33533163 DOI: 10.1002/smll.202005133] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/24/2020] [Indexed: 06/12/2023]
Abstract
It is a tough challenge for many decades to decipher the complex relationships between cell behaviors and cellular physical properties. Single particle tracking (SPT) with high spatial and temporal resolution has been applied extensively in cell research to understand physicochemical properties of cells and their bio-functions by tracking endogenous or exogenous probes. This review describes the fundamental principles of SPT as well as its applications in intracellular mechanics, membrane dynamics, organelles distribution, and processes of internalization and transport. Finally, challenges and future directions of SPT are also discussed.
Collapse
Affiliation(s)
- Zhao Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Xuejing Wang
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310058, China
| | - Ying Zhang
- School of Materials and Chemical Engineering, Heilongjiang Institute of Technology, Harbin, 150027, China
| | - Weili Xu
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| |
Collapse
|
8
|
Traulsen J, Zagami C, Daddi AA, Boccellato F. Molecular modelling of the gastric barrier response, from infection to carcinogenesis. Best Pract Res Clin Gastroenterol 2021; 50-51:101737. [PMID: 33975688 DOI: 10.1016/j.bpg.2021.101737] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023]
Abstract
The lining of the stomach is a tight monolayer of epithelial cells performing functions in digestion and a protective barrier against gastric acid, toxic metabolites and infectious agents, including Helicobacter pylori. The response of the epithelial barrier to infections underlies gastric pathologies, including gastric cancer. H. pylori has the unique capacity to colonise the gastric mucosa while evading the immune system. The colonised mucosa initiates an inflammatory response to fight the infection and a strong regenerative program to avoid barrier failure and ulceration. This response changes the morphology and cell composition of the gastric epithelium and in parallel it might contribute to the accumulation of somatic mutations leading to cellular transformation. Genetically modified mice, cell lines and human-derived organoids are the main biological models to study the gastric epithelial barrier. With these models it is possible to dissect the stepwise process of tissue adaptation to infection that places the epithelium at risk of malignant transformation.
Collapse
Affiliation(s)
- Jan Traulsen
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, United Kingdom.
| | - Claudia Zagami
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, United Kingdom.
| | - Alice Anna Daddi
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, United Kingdom.
| | - Francesco Boccellato
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, United Kingdom.
| |
Collapse
|
9
|
Eletto D, Vllahu M, Mentucci F, Del Gaudio P, Petrella A, Porta A, Tosco A. TFF1 Induces Aggregation and Reduces Motility of Helicobacter pylori. Int J Mol Sci 2021; 22:ijms22041851. [PMID: 33673347 PMCID: PMC7918695 DOI: 10.3390/ijms22041851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/05/2021] [Accepted: 02/09/2021] [Indexed: 12/21/2022] Open
Abstract
Gastric cancer is considered one of the most common malignancies in humans and Helicobacter pylori infection is the major environmental risk factor of gastric cancer development. Given the high spread of this bacterium whose infection is mostly asymptomatic, H. pylori colonization persists for a long time, becoming chronic and predisposing to malignant transformation. The first defensive barrier from bacterial infection is constituted by the gastric mucosa that secretes several protective factors, among which is the trefoil factor 1 (TFF1), that, as mucin 5AC, binds the bacterium. Even if the protective role of TFF1 is well-documented, the molecular mechanisms that confer a beneficial function to the interaction among TFF1 and H. pylori remain still unclear. Here we analyze the effects of this interaction on H. pylori at morphological and molecular levels by means of microscopic observation, chemiotaxis and motility assays and real-time PCR analysis. Our results show that TFF1 favors aggregation of H. pylori and significantly slows down the motility of the bacterium across the mucus. Such aggregates significantly reduce both flgE and flaB gene transcription compared with bacteria not incubated with TFF1. Finally, our results suggest that the interaction between TFF1 and the bacterium may explain the frequent persistence of H. pylori in the human host without inducing disease.
Collapse
Affiliation(s)
- Daniela Eletto
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
| | - Megi Vllahu
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
| | - Fatima Mentucci
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
- PhD Program in Drug Discovery and Development, University of Salerno, 84084 Fisciano (SA), Italy
| | - Pasquale Del Gaudio
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
| | - Antonello Petrella
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
| | - Amalia Porta
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
- Correspondence: (A.P.); (A.T.); Tel.: +39-089-969455 (A.P.); +39-089-969797 (A.T.)
| | - Alessandra Tosco
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy; (D.E.); (M.V.); (F.M.); (P.D.G.); (A.P.)
- Correspondence: (A.P.); (A.T.); Tel.: +39-089-969455 (A.P.); +39-089-969797 (A.T.)
| |
Collapse
|
10
|
Arzi RS, Sosnik A, Cohen N. A Microscopically Motivated Model for Particle Penetration into Swollen Biological Networks. Polymers (Basel) 2020; 12:polym12091912. [PMID: 32854259 PMCID: PMC7565132 DOI: 10.3390/polym12091912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 12/21/2022] Open
Abstract
Biological gels (bio-gels) are hydrated polymer networks that serve diverse biological functions, which often lead to intentional or unintentional exposure to particulate matter. In this work, we derive a microscopically motivated framework that enables the investigation of penetration mechanisms into bio-gels. We distinguish between two types of mechanisms: spontaneous (unforced) penetration and forced penetration. Using experimental data available in the literature, we exploit the proposed model to characterize and compare between the microstructures of respiratory, intestinal, and cervicovaginal mucus and two types of biofilms. Next, we investigate the forced penetration process of spherical and ellipsoidal particles into a locally quadrilateral network. The proposed framework can be used to improve and complement the analysis of experimental findings in vitro, ex vivo, and in vivo. Additionally, the insights from this work pave the way towards enhanced designs of nano-medicines and allow the assessment of risk factors related to the nano-pollutants exposure.
Collapse
Affiliation(s)
- Roni Sverdlov Arzi
- Laboratory of Pharmaceutical Nanomaterials Science, Department of Materials Science and Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel;
- Mechanics of Soft Materials, Department of Materials Science and Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Alejandro Sosnik
- Laboratory of Pharmaceutical Nanomaterials Science, Department of Materials Science and Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel;
- Correspondence: (A.S.); (N.C.)
| | - Noy Cohen
- Mechanics of Soft Materials, Department of Materials Science and Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel
- Correspondence: (A.S.); (N.C.)
| |
Collapse
|
11
|
Taylor JA, Sichel SR, Salama NR. Bent Bacteria: A Comparison of Cell Shape Mechanisms in Proteobacteria. Annu Rev Microbiol 2019; 73:457-480. [PMID: 31206344 DOI: 10.1146/annurev-micro-020518-115919] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Helical cell shape appears throughout the bacterial phylogenetic tree. Recent exciting work characterizing cell shape mutants in a number of curved and helical Proteobacteria is beginning to suggest possible mechanisms and provide tools to assess functional significance. We focus here on Caulobacter crescentus, Vibrio cholerae, Helicobacter pylori, and Campylobacter jejuni, organisms from three classes of Proteobacteria that live in diverse environments, from freshwater and saltwater to distinct compartments within the gastrointestinal tract of humans and birds. Comparisons among these bacteria reveal common themes as well as unique solutions to the task of maintaining cell curvature. While motility appears to be influenced in all these bacteria when cell shape is perturbed, consequences on niche colonization are diverse, suggesting the need to consider additional selective pressures.
Collapse
Affiliation(s)
- Jennifer A Taylor
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA; .,Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Sophie R Sichel
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.,Molecular Medicine and Mechanisms of Disease Graduate Program, University of Washington, Seattle, Washington 98195, USA
| | - Nina R Salama
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA; .,Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| |
Collapse
|
12
|
Cherstvy AG, Thapa S, Wagner CE, Metzler R. Non-Gaussian, non-ergodic, and non-Fickian diffusion of tracers in mucin hydrogels. SOFT MATTER 2019; 15:2526-2551. [PMID: 30734041 DOI: 10.1039/c8sm02096e] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Native mucus is polymer-based soft-matter material of paramount biological importance. How non-Gaussian and non-ergodic is the diffusive spreading of pathogens in mucus? We study the passive, thermally driven motion of micron-sized tracers in hydrogels of mucins, the main polymeric component of mucus. We report the results of the Bayesian analysis for ranking several diffusion models for a set of tracer trajectories [C. E. Wagner et al., Biomacromolecules, 2017, 18, 3654]. The models with "diffusing diffusivity", fractional and standard Brownian motion are used. The likelihood functions and evidences of each model are computed, ranking the significance of each model for individual traces. We find that viscoelastic anomalous diffusion is often most probable, followed by Brownian motion, while the model with a diffusing diffusion coefficient is only realised rarely. Our analysis also clarifies the distribution of time-averaged displacements, correlations of scaling exponents and diffusion coefficients, and the degree of non-Gaussianity of displacements at varying pH levels. Weak ergodicity breaking is also quantified. We conclude that-consistent with the original study-diffusion of tracers in the mucin gels is most non-Gaussian and non-ergodic at low pH that corresponds to the most heterogeneous networks. Using the Bayesian approach with the nested-sampling algorithm, together with the quantitative analysis of multiple statistical measures, we report new insights into possible physical mechanisms of diffusion in mucin gels.
Collapse
Affiliation(s)
- Andrey G Cherstvy
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany.
| | | | | | | |
Collapse
|