We recommend ZsGreen1 and AcGFP1 for in vivo imaging studies.
Fluorescent Protein
Excitation Maxima (nm)
Emission Maxima (nm)
ZsGreen1
493
505
AcGFP1
475
505
Application: Green Fluorescent Proteins in Plant Research
Plants and plant tissues can be successfully imaged with green fluorescent proteins. Although many plants contain endogenous compounds such as phenolics that fluoresce in the green to yellow range with low excitation wavelengths (1–2), the use of proper controls eliminates the problems associated with this autofluorescence.
Figure 1. Expression of ZsGreen in soybean under white light (Panel A) and fluorescent
light (Panel B). Bar=1 cm.
Figure 2. AcGFP expression in maize tissues and plants. Panels A and D. Maize callus under white light and fluorescent light. Panels B and E. Transformed maize leaf and root under white light and fluorescent light. Panels C and F. Kernels from a segregating transformed line under white light and fluorescent light. Imaging used a Zeiss Sv-11 dissecting scope, HB100 light source, and a GFP (plant) cube; exciter HQ470/40, dichroic 495LP, emission D525/50 BP.
Application: ZsGreen Labeling of Breast Cancer Cells to Visualize Metastasis
The brightness and enhanced ability of ZsGreen to withstand fixation makes it an ideal fluorescent protein for in vivo metastasis studies. ZsGreen was used to label human estrogen receptor-positive breast cancer cells, and fluorescent whole body imaging on living, non-anesthetized, immunocompromised nude mice identified lymph node metastases that arose from estrogen-dependent tumors grown orthotopically in mammary glands. Metastatic cancer cells injected directly into the circulation were detected in bone, brain, adrenal gland, and lung by fluorescence imaging (Figures 3–4; 3).
Figure 3. Fluorescent whole body image of a mouse with bilateral solid tumors derived from estrogen receptor-positive MCF7 human breast cancer cells. Note the presence of ZsGreen-positive cells in tumors, lymphatic vessels (LV), and inguinal and axillary lymph nodes (LN).
Figure 4. Metastatic lung tumor expressing ZsGreen1. Mouse lung bearing an MCF7+ ZsGreen tumor was fixed, embedded, and sectioned. Sections were stained with hematoxylin and eosin (left; H & E) or deparaffinized, coverslipped, and imaged via fluorescence microscopy (right) [480 nm excitation; 505 nm emission; 20X objective]. ZsGreen1 fluorescence was maintained even after histological processing.
References
Stewart, N. (2006) Trends Biotechnol.24(4):155–162.
Lin, Y. et al. (2003) BMC Plant Biol. 3:10.
Harrell, J. et al. (2006) Cancer Res. 66(18):9308–9315.
