Towards 25 Billionths of a Liter

Although fruit fly (Drosophila melanogaster) is an extensively used animal model in biology, attaining organism-level samples from this tiny insect for chemical characterization has been a challenge. Previously I developed a sampling method that enabled chemical analyses of individual fruit-fly larval blood known as hemolymph (Piyankarage et al. Anal. Chem. 2008). Illustrated here is an even challenging adult fruit-fly hemolymph sampling technique. The magnified image in the centre shows an adult male fruit fly and the tip of the sampling probe (50-µm inner diameter) that enabled collection of 25 billionths of a liter (nano liter/nL) of fly-hemolymph. The image on top left comparatively illustrates the size of adult flies, larva, and sampling probe tips by gluing them on a dime (note the letters E and DI of the ONE DIME coin). On the bottom left is the sampling probe tip with Tygon tubing, which connects the tip to a vacuum pump to pull hemolymph. An image of diluted fluorescent-tagged fly-hemolymph sample is shown on bottom right while a resultant electropherogram (a chart) from the sample analyses is shown as the border. All the images were captured through a microscope due to the small size of the objects.