#LabHacks – A worm photo shoot: Stop wriggling and smile, please!

Worms have no teeth and they do not wear braces. So why does MDC researcher Andreas Ofenbauer need dental silicone when working with these little critters? Here is the explanation …

Using a microscope is, in theory, very simple. You position the object to be examined on the slide, look through the eye piece, and the object appears enlarged. In an ideal scenario, this could already result in new and exciting discoveries. In practice, however, lab workers are confronted with a plethora of small problems that all need to be solved.

This is also biologist Andreas Ofenbauer’s experience. He is investigating threadworms – or, more specifically, the species C. elegans – with a particular focus on the muscle cells. He uses a fluorescence microscope to study cell division. But this is where the first problem crops up: How can living worms, swimming around in an aqueous solution, be fixed to the microscope slide to allow him to observe them for several hours at a time?

Holding down threadworms

Andreas begins by mixing microscopically small polystyrene balls into the solution containing the miniature worms. He then places the cover slip on top of the mixture, rendering the worms practically immobile. With the worms “held still” in this way, the scientist can photograph the tiny creatures every few minutes and create a time-lapse sequence of images. Using anesthetic, he says, would also minimize the animals’ movement, but it would carry the risk of bringing the photo shoot to a premature end – in other words, the process would ultimately be fatal for the worms.

Andreas has another problem to crack. The aqueous solution he uses dries out after a while as the liquid at the edge of the cover slip evaporates – an impractical characteristic for research requiring long periods of observation. But the scientist found a special solution to this problem too: two-component silicone, which is widely used by dentists to make jaw impressions for dentures and braces.

Dental silicone to tackle evaporation

As soon as the prepared worms are in place on the slide and under the cover slip, the silicone comes into play. Andreas mixes equal parts of the two components and applies the turquoise mixture to the slide and around the cover slip on top of the worm sample. The silicone seals the opening around the cover slip and prevents evaporation. He has to work quickly when applying the silicone, as it hardens in a matter of minutes.

Andreas learned the dental silicone trick from Anje Sporbert, head of the MDC’s Advanced Light Microscopy (ALM) platform. “It was a special tip that I received during a one-on-one discussion about my project after I’d completed the general training on working with microscopes,” says Andreas, adding that this tip has already allowed him to make new and exciting discoveries about “his” threadworms.


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