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Landfield H, Kalamaris N, Wang M. Extreme dependence of dynamics on concentration in highly crowded polyelectrolyte solutions. SCIENCE ADVANCES 2024; 10:eado4976. [PMID: 38959308 PMCID: PMC11221520 DOI: 10.1126/sciadv.ado4976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/30/2024] [Indexed: 07/05/2024]
Abstract
Charge-carrying species, such as polyelectrolytes, are vital to natural and synthetic processes that rely on their dynamic behavior. Through single-particle tracking techniques, the diffusivity of individual polyelectrolyte chains and overall system viscosity are determined for concentrated polylysine solutions. These studies show scaling dependences of D ~ c-6.1 and η ~ c7.2, much stronger than theoretical predictions, drawing the applicability of power law fits into question. Similar trends are observed in concentrated solutions prepared at various pH and counterion conditions. These hindered system dynamics appear universal to polyelectrolyte systems and are attributed to the large effective excluded volumes of polyelectrolyte chains inducing glassy dynamics. The framework of the Vrentas-Duda free-volume theory is used to compare polyelectrolyte and neutral systems. Supported by this theory, excluding counterion mass from total polymer mass results in all environmental conditions collapsing onto a common trendline. These results are applicable to crowded biological systems, such as intracellular environments where protein mobility is strongly inhibited.
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Affiliation(s)
- Harrison Landfield
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nicholas Kalamaris
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
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Verbeelen T, Fernandez CA, Nguyen TH, Gupta S, Aarts R, Tabury K, Leroy B, Wattiez R, Vlaeminck SE, Leys N, Ganigué R, Mastroleo F. Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity. NPJ Microgravity 2024; 10:3. [PMID: 38200027 PMCID: PMC10781756 DOI: 10.1038/s41526-024-00345-z] [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: 09/20/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.
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Affiliation(s)
- Tom Verbeelen
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Celia Alvarez Fernandez
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Thanh Huy Nguyen
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Surya Gupta
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Raf Aarts
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Kevin Tabury
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Baptiste Leroy
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Ruddy Wattiez
- Department of Proteomics and Microbiology, University of Mons, Av. Du Champs de Mars 6, 7000, Mons, Belgium
| | - Siegfried E Vlaeminck
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
- Centre for Advanced Process Technology for Urban REsource Recovery (CAPTURE), Frieda Saeysstraat 1, 9052, Ghent, Belgium
| | - Natalie Leys
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium
- Centre for Advanced Process Technology for Urban REsource Recovery (CAPTURE), Frieda Saeysstraat 1, 9052, Ghent, Belgium
| | - Felice Mastroleo
- Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400, Mol, Belgium.
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