Hard X-ray microprobe studies of chromium(VI)-treated V79 Chinese hamster lung cells: intracellular mapping of the biotransformation products of a chromium carcinogen

Abstract

The uptake of carcinogenic and mutagenic Cr compounds and the intracellular distribution of their biotransformation products in V79 Chinese hamster lung cells were studied by synchrotron-radiation-induced X-ray emission (SRIXE). SRIXE analysis was performed on whole cells that had been treated with either Cr(III) or Cr(V) 1,10-phenanthroline complexes, or Cr(VI). The high spatial resolution (0.3 microm) and elemental sensitivity (~10(-15) g Cr/cell) of the technique provided detailed maps of Cr and other cellular elements in thin sections prepared from Cr(VI)-treated cells. The Cr carcinogen concentrated in P-rich regions corresponding to the nucleus, as well as other areas of the cell that are likely to correspond to organelles. This is the first study that has enabled the determination of the localization of the biotransformation products of Cr(VI) carcinogens in a target lung cell.

Copper Uptake, Intracellular Localization, and Speciation in Marine Microalgae Measured by Synchrotron Radiation X-ray Fluorescence and Absorption Microspectroscopy

“…10 In addition, SR-XRF is capable of elemental distribution mapping within individual cells at a resolution of 0.2-0.3 µm and has successfully been used to study the uptake of metals in mammalian cells. [12][13][14][15] Studies by Twinning and coauthors 16,17 and Diaz 18 also showed that microprobe SR-XRF was useful in determining the elemental composition and distribution of elements (Si, P, S, K, Ca, Mn, Fe, Co, Ni, Cu and Zn) in a range of marine microalgae isolated from oceanic waters and in two freshwater algae in laboratory culture media, respectively. This study uses correlative microprobe SR-XRF and XANES to investigate the internalisation of Cu in Cu-exposed marine microalgal cells to determine the toxicological modes of action of the metal.…”

Implementation of X-ray microscopy and micro-XANES analysis for investigations of the cellular uptake and cellular metabolism of transition metals

“…Most of the Cr was reduced to the impermeable Cr(III) form. Micro-SRIXE images of thin-sectioned cells ( Figure 5) showed the intracellular Cr distribution following Cr(VI) exposure [6]. Cr was localised in two distinct regions.…”

“…Na 2 Cr 2 O 7 (Merck, AR grade) was used as received. cis-[Cr(phen) 2 (OH 2 ) 2 ](NO 3 ) 3 .2.5H 2 O was prepared, purified and oxidized to produce the Cr(V) analogue as reported in the literature [4][5][6].…”

“…Whole V79 Chinese hamster lung cells were prepared for X-ray microprobe analysis according to methods detailed by Dillon, et al [6] in which the cells (~ 10 6 ) were treated with the following Cr complexes: Na 2 Hard X-ray microprobe experiments were performed on SRI-CAT beamline 2ID-D at the Advanced Photon Source, Argonne National Laboratory [6]. All measurements were conducted using a monochromatic 10-keV X-ray incident beam, and under a He atmosphere in order to eliminate the Ar Kshell fluorescence signal (from air).…”

“…Areas of (12 × 12) µm 2 were scanned in steps of 0.3 µm at 6 s per point. The analysis for each set of elemental maps was performed as described [6]. Statistical analyses were performed on the results of whole cell elemental distributions using ANOVA, Tukey-Kramer Multiple Comparison Test [7,8].…”