Studying an animal's nervous system is crucial to understanding how it functions in day-to-day life. The smaller the animal gets, the more challenging such a study can become. Using a so-called ultramicroscope, scientists at the Vienna University of Technology have developed a better way to make the nervous systems of fruit flies glow a fluorescent green, making them easy to document.
"We focused on the fruit fly Drosophila melanogaster because it is of particular interest for research into the nervous system. Unfortunately, it is particularly difficult to develop a suitable clearing method for insects," says Marko Pende, a Ph.D. student at Vienna, in a . "For the tissue to become transparent, it has to be treated with special chemicals, and in insect tissues these chemicals have always destroyed the fluorescent molecules until now."
While scientists have been able to create the glow in the past, their methods have lacked stability. Typically, making Drosophila flies transparent requires destroying certain marker molecules.
With ultramicroscopes, the tissue is illuminated with a laser beam that penetrates tissue and lights up certain molecules that lie exactly in that plane. Using this so-called lightsheet, scientists are able to create 3D models on a computer of what a nervous system looks like and how it functions.
Older ultramicroscopes were able to create planes approximately ten microns thick. By adding an additional lens, Saghafi was able to create an ultramicroscope with a focal point that can change. Not only does this add flexibility in what can be studied, the plane of study shrunk down to three microns.
"So far, we could only focus on the outer area of the tissue; now we can take a centimeter-deep look into the tissue and still get sharp images," says Hans Ulrich Dodt, head of the department of bioelectronics. "It will enable impressive, high-resolution images that will give us important insights into the way the Drosophila nervous system works."
Scientists remain interested in Drosophila flies because the insect shares 60 percent of its DNA with humans. Approximately 75 percent of known human disease genes in fruit flies. Getting a better understanding of the connections within their nervous system could allow for breakthroughs on human systems. With robots already studying their flying patterns, the new glowing microscopy could help researchers better understand neurological diseases like Alzheimer's.