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Lee S, Poojari CS, Maznichenko A, Roesel D, Swiderska I, Pohl P, Hub JS, Roke S. Dynamic Second Harmonic Imaging of Proton Translocation Through Water Needles in Lipid Membranes. J Am Chem Soc 2024; 146:19818-19827. [PMID: 38991220 PMCID: PMC11273352 DOI: 10.1021/jacs.4c02810] [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: 02/25/2024] [Revised: 06/12/2024] [Accepted: 06/13/2024] [Indexed: 07/13/2024]
Abstract
Proton translocation through lipid membranes is a fundamental process in the field of biology. Several theoretical models have been developed and presented over the years to explain the phenomenon, yet the exact mechanism is still not well understood. Here, we show that proton translocation is directly related to membrane potential fluctuations. Using high-throughput wide-field second harmonic (SH) microscopy, we report apparently universal transmembrane potential fluctuations in lipid membrane systems. Molecular simulations and free energy calculations suggest that H+ permeation proceeds predominantly across a thin, membrane-spanning water needle and that the transient transmembrane potential drives H+ ions across the water needle. This mechanism differs from the transport of other cations that require completely open pores for transport and follows naturally from the well-known Grotthuss mechanism for proton transport in bulk water. Furthermore, SH imaging and conductivity measurements reveal that the rate of proton transport depends on the structure of the hydrophobic core of bilayer membranes.
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Affiliation(s)
- Seonwoo Lee
- Laboratory
for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
and Institute of Materials Science (IMX), School of Engineering (STI),
and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Chetan S. Poojari
- Theoretical
Physics and Center for Biophysics, Saarland
University, Saarbrücken 66123, Germany
| | - Anna Maznichenko
- Institute
of Biophysics, Johannes Kepler University
Linz, Gruberstraße 40, Linz 4020, Austria
| | - David Roesel
- Laboratory
for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
and Institute of Materials Science (IMX), School of Engineering (STI),
and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Iwona Swiderska
- Laboratory
for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
and Institute of Materials Science (IMX), School of Engineering (STI),
and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Peter Pohl
- Institute
of Biophysics, Johannes Kepler University
Linz, Gruberstraße 40, Linz 4020, Austria
| | - Jochen S. Hub
- Theoretical
Physics and Center for Biophysics, Saarland
University, Saarbrücken 66123, Germany
| | - Sylvie Roke
- Laboratory
for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
and Institute of Materials Science (IMX), School of Engineering (STI),
and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
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Lim H. Harmonic Generation Microscopy 2.0: New Tricks Empowering Intravital Imaging for Neuroscience. Front Mol Biosci 2019; 6:99. [PMID: 31649934 PMCID: PMC6794408 DOI: 10.3389/fmolb.2019.00099] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 09/17/2019] [Indexed: 01/08/2023] Open
Abstract
Optical harmonic generation, e.g., second- (SHG) and third-harmonic generation (THG), provides intrinsic contrasts for three-dimensional intravital microscopy. Contrary to two-photon excited fluorescence (TPEF), however, they have found relatively specialized applications, such as imaging collagenous and non-specific tissues, respectively. Here we review recent advances that broaden the capacity of SHG and THG for imaging the central nervous system in particular. The fundamental contrast mechanisms are reviewed as they encode novel information including molecular origin, spectroscopy, functional probes, and image analysis, which lay foundations for promising future applications in neuroscience.
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Affiliation(s)
- Hyungsik Lim
- Department of Physics and Astronomy, Hunter College and the Graduate Center of the City University of New York, New York, NY, United States
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Abstract
As a "holy grail" of neuroscience, optical imaging of membrane potential could enable high resolution measurements of spiking and synaptic activity in neuronal populations. This has been partly achieved using organic voltage-sensitive dyes in vitro, or in invertebrate preparations yet unspecific staining has prevented single-cell resolution measurements from mammalian preparations in vivo. The development of genetically encoded voltage indicators (GEVIs) and chemogenetic sensors has enabled targeting voltage indicators to plasma membranes and selective neuronal populations. Here, we review recent advances in the design and use of genetic voltage indicators and discuss advantages and disadvantages of three classes of them. Although genetic voltage indicators could revolutionize neuroscience, there are still significant challenges, particularly two-photon performance. To overcome them may require cross-disciplinary collaborations, team effort, and sustained support by large-scale research initiatives.
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Affiliation(s)
- Yuki Bando
- Neurotechnology Center, Department Biological Sciences, Columbia University, 550 W 120th Street, New York, NY, 10027, USA
- Present address: Department Organ and Tissue Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Christiane Grimm
- Neurotechnology Center, Department Biological Sciences, Columbia University, 550 W 120th Street, New York, NY, 10027, USA
| | - Victor H Cornejo
- Neurotechnology Center, Department Biological Sciences, Columbia University, 550 W 120th Street, New York, NY, 10027, USA
| | - Rafael Yuste
- Neurotechnology Center, Department Biological Sciences, Columbia University, 550 W 120th Street, New York, NY, 10027, USA.
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Zhao Y, Thu Hien KT, Mizutani G, Rutt HN, Amornwachirabodee K, Okajima M, Kaneko T. Optical second-harmonic images of sacran megamolecule aggregates. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2017; 34:146-152. [PMID: 28157840 DOI: 10.1364/josaa.34.000146] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have detected a second-order nonlinear optical response from aggregates of the ampholytic megamolecular polysaccharide sacran extracted from cyanobacterial biomaterials by using optical second-harmonic-generation (SHG) microscopy. The SHG images of sacran cotton-like lump, fibers, and cast films showed SHG intensity microspots of several tens of micrometers in size. The dependence of the SHG spot intensity on an excitation light polarization angle was observed to illustrate sacran molecular orientation in these microdomains. We also observed SHG signals around a special region of the cast film edges of sacran. These results show that sacran megamolecules aggregate in several different ways.
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