Sz61tr stereo microscope

Live adult springtails were anaesthetized with diethyl ether and normal saline, and 20 individuals were dissected under an Olympus SZ61TR stereo microscope (Olympus, Tokyo, Japan). To effectively dissect the springtails, we made dissecting needles and a pair of tiny iris scissors by ourselves, and observed the springtails under a Leica DM500 biological microscope achromatic microlens equipped with a cold light illuminator (Leica, Wetzlar, Germany). Slide preparations followed standard procedures with a neutral optical resin adhesive and glutaraldehyde fixative, and stained with acid fuchsin and methylene blue, respectively. Photographs were taken using a SLR camera with a Nikon D750 + Macro lens under the Olympus SZ61TR stereo microscope. All the diagrammatic drawings were made based on our observation and photographs. Most behavioral observations were made under a camera with macro lenses.

The membrane morphology (structure, homogeneity/distribution) before and after filtration of bacterial suspensions was determined using scanning electron microscopy (SEM) imaging and optical microscopy. The SEM imaging of the samples’ surfaces and cross sections was performed using a FEI Sirion 400NC (FEI, Hillsboro, Oregon, USA) microscope at different magnifications. The membranes tested in the filtration experiments were immersed in 30 mL of 70% ethanol twice consecutively for half an hour in order inactivate viable bacterial cells and to fix them. Then, they were transferred to sterile Petri dishes and left to dry for 3 days at 37 ± 0.5 °C before further preparation for SEM analysis.
For light microscopy, selected non-tested membranes were cut into smaller square pieces (approx. 5 mm × 5 mm) and immersed in deionised water for 15 min at room temperature. Afterwards, the membrane pieces were dissected into individual slivers, which were transferred onto an objective glass, and observed under an Olympus SZ61TR stereomicroscope equipped with an Olympus DP73 camera (Olympus, Tokyo, Japan).