Biologists have made flies transparent

The new technique allows you to make biological tissue transparent and observe the structure of the nervous system inside the body of an insect.

To study the nervous system of animals, as a rule, it is necessary to resort to the preparation of sections. Occupation is difficult, time-consuming and also makes it difficult to study all the numerous connections of neurons with each other. A more elegant approach uses “enlightenment”, processing the samples in such a way as to make the “extra” biological tissues transparent and, marking the nervous system with fluorescent markers, observe it directly in the body.

Researchers at the University of Vienna technology were able to modify this method to work with fairly large insects. In conjunction with the planar illumination microscopy, he allowed to visualize the complex connections of the nerve fibers of the fruitfly – Hans-Ulrich Dodt and his colleagues write in the journal Nature Communications.
 

Drosophila head with fluorescent neuron clusters / © Vienna University of Technology

For this, the authors obtained a Drosophilus GM line, the neurons of which synthesized fluorescent protein labels. The sleepy animals were successively treated with solutions for the “clearing” of external tissues. Finally, a transparent sample was illuminated with a laser beam, which, thanks to a special optical system, was focused only on one of the coordinate axes, forming “cuts” of radiation, which allowed scanning the tissues layer by layer and obtaining a three-dimensional image of the sample. Scientists also needed to improve the microscope system, reducing the thickness of the “layers of light” from about 10 micrometers to three.

The authors are confident that the new technique will find wide application in research, will allow a better understanding of the structure and mechanism of the nervous system as a whole, and in the near future will help establish a complete connection of Drosophila – a complete description of the connections of its neurons.