PROTOCOLS
Making fine pipettes
Fauré Fremiet held that ‘Protozoology IS the art of making a pipette’
The process of isolation and cleaning protozoa can be achieved in a variety of ways, such as using gravity or phototaxis to draw the selected species through axenic or anti-biotic laced fluids. However, the most usual technique is to pick cells with a fine pipette. Fine pipettes are not available commercially, and so you have to ‘pull’ a normal glass Pasteur pipette, which, with a bit of practice, is quite easy.
You will need
- glass pipettes
- a burner
- something to protect the bench
- a repository for small bits of broken glass
| Gas burner, alocohol burners, bunsens, even paraffin lamps and candles will work.. |
Portable butane burner. Image and copyright M. Richlen. |
| Short glass pipettes, they are new. They can be sterilized in advance with the wide end plugged with cottom wool. The container holding them should be opened just before pulling. |
Glass pasteur pipettes. Image and copyright M. Richlen. |
| Light the flame. You may or may not chose to swab the bench with 70% alcohol to make it clean. If you do, it is worth remembering that alcohol is flammable. Hold the pipette in the flame, heating the region closest to the shoulder (so that the final pipette is as short as possible). Heat until the region is soft. |
Pipette being heated. Image and copyright M. Richlen. |
Remove from flame, and pull gently. The rate of pulling, or if you make the glass very liquid, then the resulting pipette will be finer. With care, you can pull to a diversity of thicknesses, down to the width of a hair, to suit a diversity of protists. The only part of the process that needs care and attention is this one, and the thing to be attentive to is the sequence - remove from flame then pull. Not, pull then remove from flame. If you are working with sterile pipettes, seal the pulled pipette by fusing the glass in the flame. This technique can be modified to make cutters, round ended pushers, and other odds and ends. |
.Pipette removed from the flame and being pulled. Image and copyright M. Richlen. |
| Place on insulated surface to cool off. Break at a width that is appropriate to the picking task. Typically, the width of the aperture should be about twice the diameter of the organism. |
.Finished pulled pipettes. So easy. Image and copyright M. Richlen. |
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