Sulfur is essential for life, playing important roles in metabolism and protein structure and function. Although information on sulfur biochemistry is highly desirable, it is an element that is difficult to study as it is not easily accessible with most biophysical techniques. However, sulfur x-ray absorption spectroscopy (XAS) is one such method and has become increasingly used for the study of sulfur in biological systems. Recently, a group of researchers from Stanford University, the University of Saskatchewan, SSRL, and ExxonMobil used SSRL's Beam Line 6-2 for an in situ sulfur XAS study of living mammalian cell cultures.

The scientists examined the uptake of taurine in specific cells as a function of time, does and polarity. Taurine is a sulfur-containing (sulfonic) acid which is present in high concentrations in animal organs and which has been implicated as a component in diverse physiological actions, in particular in osmoregulation (the active regulation of the pressure/cell volumes in bodily fluids). The cells were of a common biological cell line known as Madin-Darby canine kidney (MDCK) cells. This cell line develops into a specially arranged single layer of cells that exhibits the characteristics of kidney cells when cultured on polycarbonate membranes. Significant information was retrieved by following the "sulfonate feature" of taurine in the XAS spectra of the cell cultures, demonstrating that there was a considerable amount of taurine accumulation within the cells as a function of time, and that the uptake was mainly taking place at a certain location at the cell surface.

Gnida, M., Yu Sneeden, E., Whitin, J. C., Prince, R. C., Pickering, I. J., Korbas, M., George, G. N. "Sulfur X-ray Absorption Spectroscopy of Living Mammalian Cells: An Enabling Tool for Sulfur Metabolomics. In Situ Observation of Uptake of Taurine into MDCK Cells", 2007, Biochemistry, 46, 14735-14741.

To learn more about this research see the full scientific highlight at:
http://www- ssrl.slac.stanford.edu/research/highlights_archive/MDCK.html