Nice handwork and beautiful lab ware – building up the experiment and the first sampling

In my previous post, I told about preparations before an experiment can be started. Some more preparations  were still needed while the worms were creating new heads. Exposure sediments should be prepared – spiked, as we call it. Necessary amount of fullerenes to be added to the sediment was calculated after determining concentration of the fullerene suspension; concentration measurements are pretty beautiful, because of the purple color of fullerenes in the measuring solution.  Spiking is done by “a home-made spiking machine”, which means a metal blade stirred by a drill: it provides forceful mixing of chemical to sediment. Also, artificial freshwater for exposure jars was prepared.

Spiking the sediment with fullerene nanoparticles.
Preparing everything for the experiment. In the middle, spiking the sediment with fullerene nanoparticles.

Everything was finally ready for building up the experiment: spiked sediment, size-synchronized worms and artificial freshwater. The next step was building up the exposure jars with an aeration system. At first, the sediment was placed on the bottom and then artificial freshwater was carefully poured above the sediment. No matter how you pour the water, you always have a blended mix which has to let settle for one or two days before aeration can be started and the worms added. The next step is to let the exposure go on and maintain pH and oxygen content at suitable level for the worms.

Microcosmos with Lumbriculus variegatus, the tubes are for aeriation.
Microcosmos with Lumbriculus variegatus, the tubes are for aeriation. On the right, the worms are in their typical feeding position.

After 7 days it was time to collect the first worm samples, which means whole-day handwork. And how to carry that out? The exposure sediment was poured to a sieve and then carefully seek and pick up every worm using a dentist tool.

In the end, you must find your worms. Sieving is a handy method for that.
In the end, you must find your worms. Sieving is a handy method for that.

The worms are put to clean water to empty their guts before they are ready to be weighed in hand-made –how else 😉 – tiny foil cups. After recording wet weights, the worms are either dried or transferred to a freezer waiting for fullerene analysis.

Our laboratorian trainee Risto Pöhö weighing the worms at the end of the experiment. Note the handy tool for making weighing cups.
Our laboratorian trainee Risto Pöhö weighing the worms at the end of the experiment. Note the handy tool for making weighing cups.

Text by Kukka Pakarinen

Pictures by Kaisa Figueiredo, Risto Pöhö, and Kukka Pakarinen