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- Quantum mechanism of light energy propagation through an avian retinaPublication . Zueva, Lidia; Golubeva, Tatiana; Korneeva, Elena; Resto, Oscar; Inyushin, Mikhail; Khmelinskii, Igor; Makarov, VladimirTaking into account the ultrastructure of the Pied Flycatcher foveal retina reported earlier and the earlier reported properties of Muller cell (MC) intermediate filaments (IFs) isolated from vertebrate retina, we proposed a quantum mechanism (QM) of light energy transfer from the inner limiting membrane level to visual pigments in the photoreceptor cells. This mechanism involves electronic excitation energy transfer in a donor-acceptor system, with the IFs excited by photons acting as energy donors, and visual pigments in the photoreceptor cells acting as energy acceptors. It was shown earlier that IFs with diameter 10 nm and length 117 mu m isolated from vertebrate eye retina demonstrate properties of light energy guide, where exciton propagates along such IFs from MC endfeet area to photoreceptor cell area. The energy is mostly transferred via the contact exchange quantum mechanism. Our estimates demonstrate that energy transfer efficiencies in such systems may exceed 80-90%. Thus, the presently developed quantum mechanism of light energy transfer in the inverted retina complements the generally accepted classic optical mechanism and the mechanism whereby Muller cells transmit light like optical fibers. The proposed QM of light energy transfer in the inverted retina explains the high image contrast achieved in photopic conditions by an avian eye, being probably also active in other vertebrates.
- Electron microscopy study of the central retinal fovea in Pied flycatcher: evidence of a mechanism of light energy transmission through the retinaPublication . Zueva, Lidia; Golubeva, Tatiana; Korneeva, Elena; Resto, Oscar; Inyushin, Mikhail; Khmelinskii, Igor; Makarov, VladimirWe present unique ultrastructural data on avian retinal cells. Presently and earlier (Zueva et al., 2016) we explored distribution of intermediate filaments (IFs) in retinal cells of the Pied flycatcher (Ficedula hypoleuca, Passeriformes, Aves) in the central foveolar zone. This retinal zone only contains single and double cone photoreceptors. Previously we found that continuous IFs span Müller cells (MC) lengthwise from the retinal inner limiting membrane (ILM) layer up to the outer limiting membrane (OLM) layer. Here we describe long cylindrical bundles of IFs (IFBs) inside the cone inner segments (CIS) adjoining the cone plasma membrane, with these IFBs following along the cone lengthwise, and surrounding the cone at equal spacing one from the other. Double cones form a combined unit, wherein they are separated by their respective plasma membranes. Double cones thus have a common external ring of IFBs, surrounding both cone components. In the layer of cilia, the IFBs that continue into the cone outer segment (COS) follow on to the cone apical tip along the direction of incident light, with single IFs separating from the IFB, touching, and sometimes passing in-between the light-sensitive lamellae of the COS. These new data support our previous hypothesis on the quantum mechanism of light energy propagation through the vertebrate retina (Zueva et al., 2016, 2019).
- Spectral selectivity model for light transmission by the intermediate filaments in Muller cellsPublication . Khmelinskii, Igor; Golubeva, Tatiana; Korneeva, Elena; Inyushin, Mikhail; Zueva, Lidia; Makarov, VladimirPresently we continue our studies of the quantum mechanism of light energy transmission in the form of excitons by axisymmetric nanostructures with electrically conductive walls. Using our theoretical model, we analyzed the light energy transmission by biopolymers forming optical channels within retinal Muller cells. There are specialized intermediate filaments (IF) 10-18 nm in diameter, built of electrically conductive polypeptides. Presently, we analyzed the spectral selectivity of these nanostructures. We found that their transmission spectrum depends on their diameter and wall thickness. We also considered the classical approach, comparing the results with those predicted by the quantum mechanism. We performed experimental measurements on model quantum waveguides, made of rectangular nanometer-thick chromium (Cr) tracks. The optical spectrum of such waveguides varied with their thickness. We compared the experimental absorption/transmission spectra with those predicted by our model, with good agreement between the two. We report that the observed spectra may be explained by the same mechanisms as operating in metal nanolayers. Both the models and the experiment show that Cr nanotracks have high light transmission efficiency in a narrow spectral range, with the spectral maximum dependent on the layer thickness. Therefore, a set of intermediate filaments with different geometries may provide light transmission over the entire visible spectrum with a very high (similar to 90%) efficiency. Thus, we believe that high contrast and visual resolution in daylight are provided by the quantum mechanism of energy transfer in the form of excitons, whereas the ultimate retinal sensitivity of the night vision is provided by the classical mechanism of photons transmitted by the Muller cell light-guides.
- Foveolar muller cells of the pied flycatcher: morphology and distribution of intermediate filaments regarding cell transparencyPublication . Zueva, Lidia; Golubeva, Tatiana; Korneeva, Elena; Makarov, Vladimir; Khmelinskii, Igor; Inyushin, MikhailSpecialized intermediate filaments (IFs) have critical importance for the clearness and uncommon transparency of vertebrate lens fiber cells, although the physical mechanisms involved are poorly understood. Recently, an unusual low-scattering light transport was also described in retinal Muller cells. Exploring the function of IFs in Muller cells, we have studied the morphology and distribution pattern of IFs and other cytoskeletal filaments inside the Muller cell main processes in the foveolar part of the avian (pied flycatcher) retina. We found that some IFs surrounded by globular nanoparticles (that we suggest are crystallines) are present in almost every part of the Muller cells that span the retina, including the microvilli. Unlike IFs implicated in the mechanical architecture of the cell, these IFs are not connected to any specific cellular membranes. Instead, they are organized into bundles, passing inside the cell from the endfeet to the photoreceptor, following the geometry of the processes, and repeatedly circumventing numerous obstacles. We believe that the presently reported data effectively confirm that the model of nanooptical channels built of the IFs may provide a viable explanation of Muller cell transparency.
- Quantum mechanism of light transmission by the intermediate filaments in some specialized optically transparent cellsPublication . Makarov, Vladimir; Zueva, Lidia; Golubeva, Tatiana; Korneeva, Elena; Khmelinskii, Igor; Inyushin, MikhailSome very transparent cells in the optical tract of vertebrates, such as the lens fiber cells, possess certain types of specialized intermediate filaments (IFs) that have essential significance for their transparency. The exact mechanism describing why the IFs are so important for transparency is unknown. Recently, transparency was described also in the retinal Muller cells (MCs). We report that the main processes of the MCs contain bundles of long specialized IFs, each about 10 nm in diameter; most likely, these filaments are the channels providing light transmission to the photoreceptor cells in mammalian and avian retinas. We interpret the transmission of light in such channels using the notions of quantum confinement, describing energy transport in structures with electroconductive walls and diameter much smaller than the wavelength of the respective photons. Model calculations produce photon transmission efficiency in such channels exceeding 0.8, in optimized geometry. We infer that protein molecules make up the channels, proposing a qualitative mechanism of light transmission by such structures. The developed model may be used to describe light transmission by the IFs in any transparent cells. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)