From E.M. microprobe analysis to NMRD studies of the lens

We describe how electron microscope X-ray emission spectroscopy (XES) was the basis for recent studies of lens cytoplasm using proton nuclear magnetic resonance, NMR, relaxation methods. Although electron microscopy and NMR are very different techniques, the phosphorus distributions that were observed in whole lens using XES led to studies of proton relaxation rates in lens cytoplasm. Proton NMR is sensitive to water-protein interactions that exist in transparent lens cytoplasm. The cytoplasm is transparent because the interactions produce Fourier components in the density fluctuations of lens cytoplasm that remain small relative to the wavelength of light (1). New information on the interactions that are involved in the development and maintenance of transparent cytoplasm may be obtained using methods of proton NMRD (2).