Photochromic meta-diamides for optical modulation of ligand activity and neuron function

In order to achieve light regulation of biological functions, a series of photoswitchable azobenzene-based meta-diamide analogues were synthesized. One of the ABMDAs can lead to activity changes towards Aedes albopictus larvae upon photoisomerization and enables optical modulation of membrane potential of DUM neurons.

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TCA Cycle and Mitochondrial Membrane Potential Are Necessary for Diverse Biological Functions

Molecular Cell ◽

10.1016/j.molcel.2015.12.002 ◽

2016 ◽

Vol 61 (2) ◽

pp. 199-209 ◽

Cited By ~ 211

Author(s):

Inmaculada Martínez-Reyes ◽

Lauren P. Diebold ◽

Hyewon Kong ◽

Michael Schieber ◽

He Huang ◽

...

Keyword(s):

Membrane Potential ◽

Mitochondrial Membrane Potential ◽

Mitochondrial Membrane ◽

Tca Cycle ◽

Biological Functions

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Monitoring of relative mitochondrial membrane potential in living cells by fluorescence microscopy.

The Journal of Cell Biology ◽

10.1083/jcb.88.3.526 ◽

1981 ◽

Vol 88 (3) ◽

pp. 526-535 ◽

Cited By ~ 620

Author(s):

L V Johnson ◽

M L Walsh ◽

B J Bockus ◽

L B Chen

Keyword(s):

Membrane Potential ◽

Fluorescence Microscopy ◽

Mitochondrial Membrane Potential ◽

Mitochondrial Membrane ◽

Specific Interaction ◽

Living Cells ◽

Cellular Level ◽

Energy Requirements ◽

Active Movement ◽

Biological Functions

Permeant cationic fluorescent probes are shown to be selectively accumulated by the mitochondria of living cells. Mitochondria-specific interaction of such molecules is apparently dependent on the high trans-membrane potential (inside negative) maintained by functional mitochondria. Dissipation of the mitochondrial trans-membrane and potential by ionophores or inhibitors of electron transport eliminates the selective mitochondrial association of these compounds. The application of such potential-dependent probes in conjunction with fluorescence microscopy allows the monitoring of mitochondrial membrane potential in individual living cells. Marked elevations in mitochondria-associated probe fluorescence have been observed in cells engaged in active movement. This approach to the analysis of mitochondrial membrane potential should be of value in future investigations of the control of energy metabolism and energy requirements of specific biological functions at the cellular level.

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Light regulation of Ca2+ in the cone photoreceptor synaptic terminal

Visual Neuroscience ◽

10.1017/s0952523808080814 ◽

2008 ◽

Vol 25 (5-6) ◽

pp. 693-700 ◽

Cited By ~ 19

Author(s):

SUE-YEON CHOI ◽

SKYLER JACKMAN ◽

WALLACE B. THORESON ◽

RICHARD H. KRAMER

Keyword(s):

Membrane Potential ◽

Hot Spots ◽

Synaptic Vesicles ◽

Light Regulation ◽

Bright Light ◽

Cone Photoreceptor ◽

Two Photon ◽

Ratiometric Imaging ◽

High Level ◽

Indicator Dyes

AbstractRetinal cones are depolarized in darkness, keeping voltage-gated Ca2+ channels open and sustaining exocytosis of synaptic vesicles. Light hyperpolarizes the membrane potential, closing Ca2+ channels and suppressing exocytosis. Here, we quantify the Ca2+ concentration in cone terminals, with Ca2+ indicator dyes. Two-photon ratiometric imaging of fura-2 shows that global Ca2+ averages ~360 nM in darkness and falls to ~190 nM in bright light. Depolarizing cones from their light to their dark membrane potential reveals hot spots of Ca2+ that co-label with a fluorescent probe for the synaptic ribbon protein ribeye, consistent with tight localization of Ca2+ channels near ribbons. Measurements with a low-affinity Ca2+ indicator show that the local Ca2+ concentration near the ribbon exceeds 4 μM in darkness. The high level of Ca2+ near the ribbon combined with previous estimates of the Ca2+ sensitivity of release leads to a predicted dark release rate that is much faster than observed, suggesting that the cone synapse operates in a maintained state of synaptic depression in darkness.

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Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141238 ◽

1995 ◽

Vol 53 ◽

pp. 972-973

Author(s):

R H. Selinfreund ◽

A. H. Cornell-Bell

Keyword(s):

Membrane Potential ◽

Confocal Microscopy ◽

Patch Clamp ◽

Electrical Activity ◽

Time Lapse ◽

Neuronal Firing ◽

Neuronal Membrane ◽

Pituitary Cells ◽

Patch Clamp Recording ◽

Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

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Fluorescent potentiometric dyes for membrane-potential imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168566 ◽

1994 ◽

Vol 52 ◽

pp. 166-167

Author(s):

Leslie M. Loew

Keyword(s):

Membrane Potential ◽

Single Cells ◽

Quantitative Imaging ◽

Optical Recording ◽

Biological Processes ◽

Major Focus ◽

The Past ◽

Excitable Systems ◽

Major Application ◽

The Impact

A major application of potentiometric dyes has been the multisite optical recording of electrical activity in excitable systems. After being championed by L.B. Cohen and his colleagues for the past 20 years, the impact of this technology is rapidly being felt and is spreading to an increasing number of neuroscience laboratories. A second class of experiments involves using dyes to image membrane potential distributions in single cells by digital imaging microscopy - a major focus of this lab. These studies usually do not require the temporal resolution of multisite optical recording, being primarily focussed on slow cell biological processes, and therefore can achieve much higher spatial resolution. We have developed 2 methods for quantitative imaging of membrane potential. One method uses dual wavelength imaging of membrane-staining dyes and the other uses quantitative 3D imaging of a fluorescent lipophilic cation; the dyes used in each case were synthesized for this purpose in this laboratory.

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Membrane–cytoskeleton interactions in cholesterol-dependent domain formation

Essays in Biochemistry ◽

10.1042/bse0570177 ◽

2015 ◽

Vol 57 ◽

pp. 177-187 ◽

Cited By ~ 9

Author(s):

Jennifer N. Byrum ◽

William Rodgers

Keyword(s):

Biological Properties ◽

Membrane Rafts ◽

Membrane Domains ◽

Biological Functions ◽

Membrane Cytoskeleton ◽

Heterogeneous Structures ◽

Integral Role ◽

Model Cell ◽

Actomyosin Cytoskeleton ◽

Dependent Domain

Since the inception of the fluid mosaic model, cell membranes have come to be recognized as heterogeneous structures composed of discrete protein and lipid domains of various dimensions and biological functions. The structural and biological properties of membrane domains are represented by CDM (cholesterol-dependent membrane) domains, frequently referred to as membrane ‘rafts’. Biological functions attributed to CDMs include signal transduction. In T-cells, CDMs function in the regulation of the Src family kinase Lck (p56lck) by sequestering Lck from its activator CD45. Despite evidence of discrete CDM domains with specific functions, the mechanism by which they form and are maintained within a fluid and dynamic lipid bilayer is not completely understood. In the present chapter, we discuss recent advances showing that the actomyosin cytoskeleton has an integral role in the formation of CDM domains. Using Lck as a model, we also discuss recent findings regarding cytoskeleton-dependent CDM domain functions in protein regulation.

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