Fourier analysis of normal and cataractous nuclear fiber cell cytoplasms

Purpose. To utilize Fourier analysis to detect spatial fluctuations in normal and cataractous nuclear fiber cell cytoplasms from canine and human lenses. Methods. Fixed Vibratome sections of normal and cataractous lenses were examined with transmission electron microscopy. Cytoplasmic regions from normal canine nuclear fibers were compared to equivalent regions of opaque nuclei from spontaneous diabetic cataractous canine lenses. Likewise, normal human lens fiber cell cytoplasms were compared with cytoplasms from age-related nuclear cataractous lenses. Digitized micrographs were Fourier transformed and radial plots were made of the power spectra. Results. Transforms of normal lens cytoplasms showed a small central peak which rapidly declined in intensity. Radial plots also revealed a broad tail of intensity over the range of 10-30 nm. Transfoims of cataractous lens cytoplasms showed a larger circular area of intensity in the center, which decreased gradually rather than abruptly. The corresponding radial plots revealed greater intensity in the range of 100-300 nm and less intensity in the range 10-30 nm. These data indicate that the cataractous cytoplasms produced strong intensity in regions of large spatial fluctuations and weak intensity in regions of small fluctuations relative to transforms of the normal cytoplasms. The electron micrographs also revealed differences in the distributions of cytoplasmic proteins with the most pronounced variation occurring between the smooth normal canine cytoplasms and the granular diabetic cataractous canine cytoplasms. Conclusions. The dissimilarities in the Fourier transforms and radial plots of the normal and cataractous cytoplasms were significant and indicate that there are differences in protein distributions that complement the differences visible in electron micrographs. Intensity in transforms from normal cytoplasms could be due to a homogeneous distribution of monomers or small aggregates of the crystallin proteins. Intensity from the cataractous cytoplasms was due to objects larger in size than the crystallin monomers which could be large aggregations of crystallins or regions where crystallins have been lost.

Duke Scholars

Author Martin Joseph Costello III Ophthalmology