Czechs first to image chromosome surface structure in natural state
Czechs are the first in the world to image the chromosome surface structure in its natural state through a new imaging method with multiple applications developed by scientists from the Czech Academy of Sciences' (AV CR) institutes, Brno environmental electron microscopy team head Vilem Nedela said today.
The achievement was made by AV CR's Institute of Scientific Instruments in cooperation with the Institute of Experimental Botany.
The discovery of a surface structure with various miniature protrusions and spatially arranged fibre loops may have future implications for medicine or agriculture, among others. Chromosomes are highly sensitive structures in which hereditary information is stored.
The results are fascinating and surprising, Nedela said, adding that he believes that the benefits of the new method will rewrite biology textbooks.
The A-ESEM method opens up new possibilities for studying inanimate, but especially living matter. Until now, scanning electron microscopy, in which samples are observed in a high vacuum, has been used to image spatial structure with a resolution of up to millionths of a millimetre. Therefore, they have to undergo modifications that damage the structure.
The acronym A-ESEM stands for advanced environmental scanning electron microscopy. It allows the study of plant and, to some extent, animal cells in their natural state, such as small living animals, fungi, moulds, mites, proteins or bacteria. Scientists are also eyeing viruses in this connection. In addition, the new method enables to monitor changes in samples under the influence of temperature, desiccation, chemical reactions or physical action.
"A classical microscope can be compared to a luxury car, while an environmental microscope is a luxury car with even higher equipment, which can also drive on water and dive like a submarine, in short, it has all the functions of a classical microscope, plus many more," Nedela said.
Scientists use artificial intelligence software to advise how to set the parameters so that the sample is not destroyed. "We have used many of our own innovations and, thanks to the ultra-sensitive detectors, we observe the samples in high gas pressure and in humidity up to 100 percent, i.e. in environmentally compatible conditions - very gently, without harming them," Nedela added.
The new method, he said, is even faster, cheaper and more suitable for studying dynamic changes in biological samples than cryo-electron microscopy, which was awarded the Nobel Prize in 2017.
"The new method solves the fundamental problem of the apparent incompatibility of electron microscopy with the presence of water in the liquid state in the sample," Nedela added.
The potential of the new method was verified by the scientists in collaboration with the Olomouc Institute of Experimental Botany in the study of barley chromosomes.
For years, scientific teams from all over the world have been trying to get a detailed view of chromosomes. Only the new method has revealed that the surface is dotted with numerous protrusions, loops of chromatin fibres with an average size of around 30 nanometres, said Jaroslav Dolezel, a plant geneticist and leader of the Olomouc team.
It is also likely that the scientists have managed to image the nucleosomes on which the DNA molecule is wound like coils. Scientists do not know for sure what the protrusions on the surface are for and what they consist of. "Now we want to find out," Dolezel added.
While chromosome disorders are the cause of inherited diseases in humans, they lead to reduced fertility and yield in agricultural crops. Revealing the surface structure of chromosomes provides new insights into the structure of the hereditary apparatus, will allow the identification of disorders in it and will contribute to the development of synthetic organisms with artificially created hereditary information.