Determination of local cell membrane slope fluctuations using the pitch rotational mode of optical tweezers

2020 ◽  
Author(s):  
Rahul Vaippully ◽  
Vaibavi Ramanujam ◽  
Manoj Gopalakrishnan ◽  
Saumendra Bajpai ◽  
Basudev Roy
Keyword(s):  
Cell Membrane ◽  
Optical Tweezers ◽  
Rotational Mode ◽  
Local Cell

Detection of sub-degree angular fluctuations of the local cell membrane slope using optical tweezers

Soft Matter ◽  
2020 ◽  
Vol 16 (32) ◽  
pp. 7606-7612
Author(s):  
Rahul Vaippully ◽  
Vaibavi Ramanujan ◽  
Manoj Gopalakrishnan ◽  
Saumendra Bajpai ◽  
Basudev Roy
Keyword(s):  
Cell Membrane ◽  
Optical Tweezers ◽  
Pitch Angle ◽  
Local Cell

We ascertain pitch angle of a spherical birefringent particle using optical tweezers and use it to find cell membrane parameters.

Non-contact-based determination of membrane permeability to water and dimethyl sulfoxide of cells virtually trapped in a self-induced micro-vortex

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Hsiu-Yang Tseng ◽  
Chiu-Jen Chen ◽  
Zong-Lin Wu ◽  
Yong-Ming Ye ◽  
Guo-Zhen Huang
Keyword(s):  
Cell Membrane ◽  
Dimethyl Sulfoxide ◽  
Membrane Permeability ◽  
Cell Membrane Permeability ◽  
Cell Type ◽  
Cryoprotective Agents ◽  
A Cell

Cell-membrane permeability to water (Lp) and cryoprotective agents (Ps) of a cell type is a crucial cellular information for achieving optimal cryopreservation in the biobanking industry. In this work, a...

scholarly journals Local Cell Membrane Deformations due to Receptor-Ligand Bonding as Seen by Reflection Microscopy

2002 ◽  
Vol 9 (3) ◽  
pp. 161-172 ◽  
Author(s):  
J. Galle ◽  
I. Reibiger ◽  
M. Westermann ◽  
W. Richter ◽  
S. Löffler
Keyword(s):  
Cell Membrane ◽  
Receptor Ligand ◽  
Local Cell ◽  
Membrane Deformations

scholarly journals Probiotic Bacteria May Become Dormant during Storage

2005 ◽  
Vol 71 (3) ◽  
pp. 1662-1663 ◽  
Author(s):  
Sampo J. Lahtinen ◽  
Miguel Gueimonde ◽  
Arthur C. Ouwehand ◽  
Johanna P. Reinikainen ◽  
Seppo J. Salminen
Keyword(s):  
Cell Membrane ◽  
Clinical Significance ◽  
Probiotic Bacteria ◽  
Bacterial Viability ◽  
Viable Cells ◽  
Nonculturable Cells

ABSTRACT The determination of bacterial viability in probiotic products is of economic, technological, and clinical significance. We compared four methods to enumerate three Bifidobacterium strains in fermented oat products during storage. A subpopulation of nonculturable cells retained a functional cell membrane typical of viable cells, indicating that probiotic bacteria become dormant during storage.

scholarly journals Extreme mechanical diversity of human telomeric DNA revealed by fluorescence-force spectroscopy

2019 ◽  
Vol 116 (17) ◽  
pp. 8350-8359 ◽  
Author(s):  
Jaba Mitra ◽  
Monika A. Makurath ◽  
Thuy T. M. Ngo ◽  
Alice Troitskaia ◽  
Yann R. Chemla ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Conformational Changes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Force Spectroscopy ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Substitution Mutant

G-quadruplexes (GQs) can adopt diverse structures and are functionally implicated in transcription, replication, translation, and maintenance of telomere. Their conformational diversity under physiological levels of mechanical stress, however, is poorly understood. We used single-molecule fluorescence-force spectroscopy that combines fluorescence resonance energy transfer with optical tweezers to measure human telomeric sequences under tension. Abrupt GQ unfolding with K+in solution occurred at as many as four discrete levels of force. Added to an ultrastable state and a gradually unfolding state, there were six mechanically distinct structures. Extreme mechanical diversity was also observed with Na+, although GQs were mechanically weaker. Our ability to detect small conformational changes at low forces enabled the determination of refolding forces of about 2 pN. Refolding was rapid and stochastically redistributed molecules to mechanically distinct states. A single guanine-to-thymine substitution mutant required much higher ion concentrations to display GQ-like unfolding and refolded via intermediates, contrary to the wild type. Contradicting an earlier proposal, truncation to three hexanucleotide repeats resulted in a single-stranded DNA-like mechanical behavior under all conditions, indicating that at least four repeats are required to form mechanically stable structures.

Hydraulische Leitfähigkeit von Valonia utricularis / Hydraulic Conductivity of Valonia utricularis

1971 ◽  
Vol 26 (12) ◽  
pp. 1302-1311 ◽  
Author(s):  
E. Steudle ◽  
U. Zimmermann
Keyword(s):  
Hydraulic Conductivity ◽  
Cell Membrane ◽  
Marine Alga ◽  
Water Movement ◽  
Turgor Pressure ◽  
Irreversible Thermodynamics ◽  
Rapid Changes ◽  
Cell Turgor ◽  
Valonia Utricularis

A method is described for the simultaneous determination of rapid changes of the cell turgor pressure (hydrostatic pressure) in algal cells (cell size must be at least 3 mm in diameter), and of the net volume flow across the cell membrane arising after a change of the cell turgor pressure or of the osmotic pressure in the outside medium. On the basis of the equations of irreversible thermodynamics it is possible to calculate the hydraulic conductivity of the cell membrane from these measurements, as it is theoretically shown.The hydraulic conductivities of the marine alga Valonia utricularis determined in two independent ways (by osmotic and hydrostatic experiments) are equal. For exosmosis, Lpex (hydrostatic) and Lpex (osmotic) amounted to (9,6 ± 1,0) ·10-7 and (9,8 ± 1,9) · 10-7 respectively cm · sec-1 · atm-1, and for endomosis, Lpen (hydrostatic) was (9,4 ± 1,1) ·10-7 cm · sec-1 · atm-1.A polarity in the water movement across the cell membranes as discussed in the literature could not be found for Valonia utricularis.

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