DNA is alive and glowing
Biologists have learned to "highlight" DNA in living cells
Swiss scientists have realized the dream of many molecular biologists – they have developed a special compound that makes DNA molecules glow and illuminate the entire cell without disturbing its vital activity, which will allow scientists to uncover many secrets of life, according to an article published in Nature Communications (Lukinavičius et al., SiR–Hoechst is a far-red DNA stain for live-cell nanoscopy).
"The creation of this dye, SiR-Hoechst, brings us closer to the realization of the main task of microscopy – observing the life and wonders of nature, without disturbing their life and natural flow," said Kai Johnson from the Swiss Federal Polytechnic School in Lausanne (in a press release EPFL New DNA stain lights up living cells – VM).
As Johnson explains, today biologists use a whole lot of luminous tags that can attach to DNA molecules, proteins and other components of cells and "highlight" them, allowing scientists to study the internal structure of the microcosm.
All these fluorescent labels have one key drawback – they cannot be used for experiments with living tissues and cells. This is due to two reasons – the toxicity of such compounds, as well as the fact that either ultraviolet or just blue light is used for the operation of these dyes, which very quickly destroy cells and irreversibly damage DNA.
Biotechnologists from the Federal Polytechnic School were able to eliminate both of these shortcomings by combining two substances – the red dye rhodamine, a non-toxic version of which was created in Johnson's laboratory, and the fluorescent substance bisbenzimide, which usually reacts to blue rays.
Their compound, the SiR-Hoechst dye, as scientists called it, is devoid of the shortcomings of its progenitors – it is non-toxic by nature, reacts to red, not blue light, and glows only when its molecules attach to the DNA helix.
The latter property is an important "bonus", since it allows you to use this paint for observing cells in very high resolution, which is impossible to do in the case of conventional fluorescent dyes.
Mitosis of HeLa – VM living cells
As experiments on cancer cell cultures have shown, SiR-Hoechst has almost no effect on cell function and does not cause damage even with very long continuous observations. According to scientists, the cells marked with it remained alive even a day after they were irradiated with a red laser.
After making sure that the paint was safe for individual cells, the scientists moved on to the final experiment – they marked the skin cells in the fruit fly embryo with SiR-Hoechst, which allowed them to track how they divided and what happened to the DNA strands during this process. Johnson and his colleagues hope that this paint will help scientists uncover many other secrets of the life of single cells and tissues, and understand how viruses and other pathogens enter cells and multiply in them.
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01.10.2015