Electrophoresis and orientation of F-actin in agarose gels

Borejdo, Julian; Ortega, Henry W.

doi:10.1016/s0006-3495(89)82675-x

Cited by 11 publications

(3 citation statements)

References 35 publications

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“…Electrical current applied to actin filaments suspended in a solution-filled well located between two gold electrodes results in those actin filaments aligning parallel to the electric lines and bridging the intervening gap between electrodes [ 59 ]. Other studies similarly indicate that actin filaments possess the ability to align parallel and perpendicular to the electric field depending on the nature of the field [ 60 , 61 ]. It is also conceivable that electric or magnetic fields contribute to neural structure.…”

Section: Electric Signal Propagation By Actin Filamentsmentioning

confidence: 99%

“…Additionally, the aforementioned models lack a true memory of recent inputs and are therefore unable to process the current information within the context of the recently observed data. As such, these models are inadequate and inappropriate tools with which to study real neurons, in particular the highly dynamic behavior observed during synaptic activation and with neural plasticity [ 59 , 60 , 81 , 82 ]. While synapses in ANN vary slowly during the learning process, these synapses are assumed to be static after the learning phase is over.…”

Section: Dendritic Cytoskeleton Information Processing Modelmentioning

confidence: 99%

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Neural cytoskeleton capabilities for learning and memory

2009

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This paper proposes a physical model involving the key structures within the neural cytoskeleton as major players in molecular-level processing of information required for learning and memory storage. In particular, actin filaments and microtubules are macromolecules having highly charged surfaces that enable them to conduct electric signals. The biophysical properties of these filaments relevant to the conduction of ionic current include a condensation of counterions on the filament surface and a nonlinear complex physical structure conducive to the generation of modulated waves. Cytoskeletal filaments are often directly connected with both ionotropic and metabotropic types of membraneembedded receptors, thereby linking synaptic inputs to intracellular functions. Possible roles for cable-like, conductive filaments in neurons include intracellular information processing, regulating developmental plasticity, and mediating transport. The cytoskeletal proteins form a complex network capable of emergent information processing, and they stand to intervene between inputs to and outputs from neurons. In this manner, the cytoskeletal matrix is proposed to work with neuronal membrane and its intrinsic components (e.g., ion channels, scaffolding proteins, and adaptor proteins), especially at sites of synaptic contacts and spines. An information processing model based on cytoskeletal networks is proposed that may underlie certain types of learning and memory.

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Section: Electric Signal Propagation By Actin Filamentsmentioning

confidence: 99%

Section: Dendritic Cytoskeleton Information Processing Modelmentioning

confidence: 99%

Neural cytoskeleton capabilities for learning and memory

2009

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“…Therefore, an approach must be taken to orient solutions ofpurified actin for study in EPR experiments. Previously, investigators have oriented actin in strong magnetic fields (Torbet and Dickens, 1984), by the flow of actin solutions (Miki and Mihashi, 1977), by the flow of actin sols (Popp et al, 1987), and by the electrophoresis of actin in agarose gels (Borejdo and Ortega, 1989). In the present study, we have oriented actin solutions by flow and determined the orientational distribution of the spin labels rigidly bound to actin.…”

Section: Introductionmentioning

confidence: 99%

Orientational distribution of spin-labeled actin oriented by flow

Ostap¹,

Yanagida²,

Thomas³

1992

Biophysical Journal

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Previous studies on spin-labeled F-actin (MSL-actin), using saturation transfer electron paramagnetic resonance (ST-EPR), have demonstrated that actin has submillisecond rotational flexibility and that this flexibility is affected by the binding of myosin and its subfragments. This rotational flexibility does not change during the active interaction of myosin heads, actin, and adenosine triphosphate. However, these ST-EPR studies, performed on randomly oriented actin, would not be sensitive to orientational changes on the millisecond time scale or slower. In the present study, we have clarified these results by performing conventional EPR experiments on MSL-actin oriented by flow to detect changes in the orientational distribution. We have determined the orientational distribution of the spin labels relative to the magnetic field (flow direction) by comparing experimental EPR spectra to simulated EPR spectra corresponding to known orientational distributions. Spectra acquired during flow indicate two populations of probes: a highly ordered population and a disordered population. For the ordered population (28% of the total spin concentration), the angle between the actin filament axis and the nitroxide z axis (theta) fits a Gaussian distribution centered at 32.0 +/- 0.9 degrees, with a full width at half maximum of 20.7 +/- 3.9 degrees. The angle between the nitroxide x axis and the projection of the field in the xy plane (phi) is centered at 37.5 +/- 9.2 degrees with a full width of 24.9 +/- 10.7 degrees. This orientational distribution is not significantly changed upon the binding of phalloidin or myosin subfragment 1 (S1), indicating that these proteins do not affect the axial orientation of actin subunits. Spectra of spin-labeled S1 (MSL-S1) bound to actin oriented by flow have about the same orientational distribution as MSL-S1 bound to actin in oriented fibers. Thus, the oriented fraction of flow-oriented actin filaments has nearly the same high degree of alignment as the actin filaments in muscle fibers.

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The Cytoskeleton as a Nanoscale Information Processor: Electrical Properties and an Actin-Microtubule Network Model

Woolf¹,

Priel²,

Tuszyński³

2009

Nanoneuroscience

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One of the major goals of nanotechnology is to advance the field of information processing. The central processing units of the future are likely to be quite different from those currently used. While biomolecular processors are unlikely to displace semiconductor processors for speed and accuracy, certain proteins may offer solutions to problems confronting logical processor design, including self-assembly and emergent computation. Cytoskeletal proteins may prove useful as biomolecular processors or may inspire hybrid designs. Actin filaments and microtubules, for example, have highly charged surfaces that enable them to conduct electric currents and process information. The biophysical properties of these filaments relevant to the conduction of ionic current include a condensation of counterions on the filament surface, the non-linear complex physical structure, and in the case of microtubules, nanopores that allow ions to pass between the outer environment to the microtubule lumen. Possible roles for cable-like, conductive filaments in neurons include intracellular information processing, regulation of developmental plasticity, and mediation of transport. Operating as an interconnected matrix, cytoskeletal proteins form a complex network capable of emergent information processing; moreover, they stand to intervene between inputs to and outputs from neurons. The cytoskeletal matrix receives information from the neuronal membrane and its intrinsic components (e.g., ion channels, scaffolding proteins, and adaptor proteins), especially at sites of synaptic contacts and spines, and in turn affects the output of the neuron. An information-processing model based on cytoskeletal networks is described, which may underlie certain types of learning and memory. 863 The Cytoskeleton as a Nanoscale Information Processor 3.

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Electrophoresis and orientation of F-actin in agarose gels

Cited by 11 publications

References 35 publications

Neural cytoskeleton capabilities for learning and memory

Neural cytoskeleton capabilities for learning and memory

Orientational distribution of spin-labeled actin oriented by flow

The Cytoskeleton as a Nanoscale Information Processor: Electrical Properties and an Actin-Microtubule Network Model

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