IR spectroscopic characteristics of cell cycle and cell death probed by synchrotron radiation based fourier transform IR spectromicroscopy

Synchrotron radiation based Fourier transform IR (SR-FTIR) spectromicroscop y allows the study of individual living cells with a high signal to noise r atio. Here we report the use of the SR-FTIR technique to investigate change s in IR spectral features from individual human lung fibroblast (IMR-90) ce lls in vitro at different points in their cell cycle. Clear changes are obs erved in the spectral regions corresponding to proteins, DNA, and RNA as a cell changes from the G(1)-phase to the S-phase and finally into mitosis. T hese spectral changes include markers for the changing secondary structure of proteins in the cell, as well as variations in DNA/RNA content and packi ng as the cell cycle progresses, We also observe spectral features that ind icate that occasional cells are undergoing various steps in the process of cell death. The dying or dead cell has a shift in the protein amide I and I I bands corresponding to changing protein morphologies, and a significant i ncrease in the intensity of an ester carbonyl C=O peak at 1743 cm(-1) is ob served. (C) 2000 John Wiley & Sons, Inc.