PMC

Distribution of elements in mouse and naked mole rat kidneys. Paraffin-embedded kidney sections (5 μm) from mice and naked mole rats were mounted on silicon nitride windows and elemental distribution of phosphorus, sulfur, and Se was mapped using synchrotron XFM. Phosphorus and sulfur maps were used to visualize the morphology of the tissue sections. Images were obtained with 1.5 sec dwell time and 1 μm steps at the incident energy 13 keV. Maximum and minimum threshold values are given above each image. (To see this illustration in color the reader is referred to the web version of this article at www.liebertonline.com/ars).

ICP-MS and immunohistochemical analyses of GPx3 knockout mice. (A) ICP-MS analysis of Se in GPx3 knockout mice. Lysates from freshly frozen tissues were normalized for protein content, digested in 15% nitric acid, 15% hydrogen peroxide, and analyzed by ICP-MS. 50 ppb gallium was used as an internal control. Statistical difference was validated by the unpaired Student t-test (n=6). Significance is indicated above the bars. (B) Immunohistochemical analysis of SelP and GPx3 in mouse kidney. Upper panels: Paraffin sections were incubated with anti-GPx3 (1:2000 dilution) and detected with Alexa-647 conjugated secondary antibodies. GPx3 is localized to the basement membrane of proximal tubules in kidney. Lower panels: Paraffin sections were incubated with anti-SelP (1:1000 dilution). SelP was visualized with Alexa-488 antibodies. SelP is localized to the lumen of proximal tubules. (To see this illustration in color the reader is referred to the web version of this article at www.liebertonline.com/ars).

Elemental distribution in kidneys of wild-type and selenoprotein knockout mice. (A) Elemental distribution in kidneys of wild-type and SelP knockout mice. Mouse tissues were fixed and paraffin embedded. Five-micron sections were mounted on the silicon nitride windows. Se, P, and S distributions of the boxed region (H&E image) were analyzed using XFM. Following elemental mapping, the morphology of the tissues was confirmed using hematoxylin/eosin staining (H&E). Se was primarily localized to the basement membrane of proximal tubules (arrows). This distribution was not altered in the SelP knockout. (B) Elemental distribution in kidneys of control and GPx3 knockout mice. Mouse tissues were fixed and paraffin embedded. Five-micron sections were mounted on the silicon nitride windows. P, S, and Se inside the boxed region were imaged using XFM. Phosphorus and sulfur images are used to show tissue morphology. Images were obtained with 1.5 sec dwell time and 1 μm steps at the incident energy 13 keV. Maximum and minimum threshold values are given above each image. (To see this illustration in color the reader is referred to the web version of this article at www.liebertonline.com/ars).

XFM of Se in mouse liver and kidney. (A) XFM scans of livers from wild-type and liver-specific Sec tRNA^[Ser]Sec knockout mice. Paraffin embedded sections (5 μm) from livers of C57BL/6J mice (WT liver) on a normal diet and the corresponding mice characterized by liver-specific Sec tRNA^[Ser]Sec knockout maintained on a Se-deficient diet (low Se KO liver) were mounted on silicon nitride windows, and both light microscope and XFM images were obtained. Se maps are shown in the figure. Maximum and minimum threshold values are given above each image. The scan was obtained by using 13 keV incident energy with a dwell time of 4 sec per pixel and 0.4 μm steps through the sample. (B) XFM of Se in different regions of mouse kidney. Paraffin sections of mouse kidney were mounted on silicon nitride windows and analyzed using XFM. Se distribution was analyzed in glomeruli, proximal tubules, and distal tubules. Arrows indicate the areas of low Se signal. Phosphorus and sulfur maps were used to visualize the morphology of the tissue sections. The data were obtained using 13 keV incident energy with a dwell time of 1.8 sec per pixel and 1 μm steps through the samples. Maximum and minimum threshold values are given above each image. (To see this illustration in color the reader is referred to the web version of this article at www.liebertonline.com/ars).