"This method allows us to see what has never been seen before, and to measure what has never before been measured," Lechene says. "Imagine looking into a building, slice by slice. You can see not only that it contains apartments, but also that each apartment contains a refrigerator. You can see that there are tomatoes in the refrigerator of one apartment, and potatoes in the refrigerator of another. You can count how many there are and measure how fast they are used and replaced. It is this level of resolution and quantification that MIMS makes possible within cells."
Lechene, of Harvard Medical School and Brigham and Women's Hospital in the US, worked with colleagues from around the world to develop and test the new methodology.
A beam of ions is used to bombard the surface atoms of the biological sample, and a fraction of the atoms are emitted and ionized. These "secondary ions" can then be manipulated with ion optics ?in the way lenses and prisms manipulate visible light - to create an atomic mass image of the sample. Lechene et al. developed MIMS by combining the use of a novel secondary-ion mass spectrometer developed by Georges Slodzian, from the Université Paris-Sud in France, labeling with stable isotopes and building quantitative image-analysis software.
MIMS can generate quantitative, three-dimensional images of proteins, DNA , RNA, sugar and fatty acids at a subcellular level in tissue sections or cells. "Using MIMS, we can image and quantify the fate of these molecules when they go into cells, where they go, and how quickly they are replaced," says Lechene.
The method does not need staining or use of radioactive labelling. Instead, it is possible to use stable isotopes to track molecules. For example, researchers could track stem cells by labelling DNA with 15N. "These stable isotopes do not alter the DNA and are not toxic to people; with MIMS and stable isotope labelling we could track these cells, where they are and how they have changed several years later," says Lechene.
"The most significant feature of this technique is that it opens up a whole new world of imaging; we haven't yet imagined all that we can do with it," says Peter Gillespie from the Oregon Health and Science University in Portland, USA in an accompanying news article, also published today in Journal of Biology.
Related biology news :
1. Marine sponge yields nanoscale secrets
2. Rice scientists make first nanoscale pH meter
3. Blood-compatible nanoscale materials possible using heparin
4. Embryonic stem cells do better on bumpy nanoscale mattress
5. Spelling out cancer on the nanoscale
6. Researchers to develop active nanoscale surfaces for biological separations
7. Bones at the nanoscale
8. Penn researcher shows that DNA gets kinky easily at the nanoscale
9. NYU researchers simulate molecular biological clock
10. Automatic extraction of gene/protein biological functions from biomedical text
11. DuPonts first biologically derived polymer receives global recognition