We obtained eye-specific measurements of the complex effects of IOP on the LC with unprecedented resolution in uncut and unfixed human eyes. Our technique was robust to electronic and speckle noise. Elevated IOP produced substantial in-plane LC stretch and compression. Further research will explore the effects of IOP on the LC in a three-dimensional framework.
Theoretical arguments and results of molecular dynamics (MD) simulations of myoglobin at 300 K are presented to relate rates of vibrational energy transfer across nonbonded contacts interacting via short-range potentials to dynamics of the contact. Both theory and the results of the simulations support a scaling relation between the energy transfer rate and the inverse of the variance in the distance between hydrogen-bonded contacts. The results of the MD simulations do not support such a relation for longer-range charged contacts. Instead, the energy transfer rate is found to scale as a power law in the distance between charged groups. The scaling between rates of vibrational energy transfer across nonbonded contacts interacting via short-range potentials and conformational dynamics suggests a relation between vibrational energy transfer rates and entropy associated with the dynamics of interacting residues. The use of time-resolved vibrational spectroscopy to determine change in conformational entropy with change in protein functional state is discussed, and an expression quantifying the connection is provided.
Energy
transport during chemical reactions or following photoexcitation
in systems of biological molecules is mediated by numerous interfaces
that separate chemical groups and molecules. Describing and predicting
energy transport has been complicated by the inhomogeneous environment
through which it occurs, and general rules are still lacking. We discuss
recent work on identification of networks for vibrational energy transport
in biomolecules and their environment, with focus on the nature of
energy transfer across interfaces. Energy transport is influenced
both by structure of the biomolecular system as well as by equilibrium
fluctuations of nonbonded contacts between chemical groups, biomolecules,
and water along the network. We also discuss recent theoretical and
computational work on the related topic of thermal transport through
molecular interfaces, with focus on systems important in biology as
well as relevant experimental studies.
Current immunofluorescence protocols are limited as they do not provide reliable antibody staining within large tissue volumes (mm3) and cannot localise and quantify multiple antigens or cell populations in the same tissue at high resolution. To address this limitation, we have developed an approach to three-dimensionally visualise large tissue volumes (mm3) at high resolution (<1 µm) and with multiple antigen labelling, for volumetric and quantitative analysis. This is made possible through computer reconstruction of serial sectioned and sequentially immunostained butyl-methyl methacrylate (BMMA) embedded tissue. Using this novel immunofluorescent computed tomography (ICT) approach, we have three-dimensionally reconstructed part of the murine lower eyelid that contains the meibomian gland and localised cell nuclei (DAPI), Ki67 and cytokeratin 1 (CK1), as well as performing non-linear optical (NLO) microscopy imaging of collagen, to assess cell density, cell proliferation, gland keratinisation and gland volume respectively. Antigenicity was maintained after four iterative stains on the same tissue, suggesting that there is no defined limit to the number of antigens that can be immunostained for reconstruction, as long as the sections remain intact and the previous antibody has been successfully eluted. BMMA resin embedding also preserved fluorescence of transgenic proteins. We propose that ICT may provide valuable high resolution, three-dimensional biological maps of multiple biomolecules within a single tissue or organ to better characterise and quantify tissue structure and function.
Molecular dynamics simulations of the villin headpiece subdomain HP36 have been carried out to examine relations between rates of vibrational energy transfer across noncovalently bonded contacts and equilibrium structural fluctuations, with focus on van der Waals contacts. Rates of energy transfer across van der Waals contacts vary inversely with the variance of the contact length, with the same constant of proportionality for all nonpolar contacts of HP36. A similar relation is observed for hydrogen bonds, but the proportionality depends on contact pairs, with hydrogen bonds stabilizing the α-helices all exhibiting the same constant of proportionality, one that is distinct from those computed for other polar contacts. Rates of energy transfer across van der Waals contacts are found to be up to 2 orders of magnitude smaller than rates of energy transfer across polar contacts.
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