How to isolate an amoeboid?

Isolation Techniques

While a stereo microscope is useful, an inverted microscope is much more convenient for isolating amoeboid organisms.

My primary tools are fine needles and micro-pipettes. I craft fine needles using insect pins or sable hairs from brushes, which I attach to small sticks with glue. Micro-pipettes are made from glass tubes: I heat a tube over a gas flame until it softens, then pull both ends apart to form a thin glass filament. This filament can be broken or cut with a knife or scissors, creating two pipettes. Often, the thin ends are not hollow, so I locate the hollow section and cut it again to create a functional pipette. To complete the tool, I attach a balloon to the other end.

Not all pipettes have a sufficiently narrow tip, so finding the right one takes practice. Fortunately, glass tubes, balloons, and insect needles are inexpensive and easily ordered.

To scan samples quickly, I use Petri dishes. If I find an interesting amoeboid, I capture it with a pipette, transfer it to a microscope slide, and examine it with my stereo or inverted microscope.

Once located, the amoeboid is trapped in a small droplet of water (see drawing below, A). Using another pipette, I place a drop of distilled water (B) next to the droplet containing the amoeboid. I then use a fine needle or sable hair to guide the amoeboid to the edge of its droplet and, with a swift motion, sweep it out. During this movement, the amoeboid becomes suspended in a small droplet (B) between the original and distilled water droplets. Continuing the sweep, I guide the amoeboid into the distilled water droplet (C) in one continuous motion.

If other organisms are present, I repeat the process until the amoeboid is isolated in a single droplet. To finalize, I remove older droplets with a tissue and add fresh distilled water to the isolated droplet. This makes it easier to transfer the amoeboid to a culture dish or test tube.

Though this method may sound challenging, it becomes straightforward with patience and practice.