The CAFÉ assay was performed as described in Delventhal et al. (Delventhal et al., 2017 (link)), similar to the assay described originally (Ja et al., 2007 (link)). A chamber was prepared by filling a 50 ml plastic Falcon conical tube with 30 ml of 2% agarose. Two holes were punched into the cap, and shortened 1 ml pipette tips were inserted through the holes partially into the chamber. Calibrated glass capillary tubes (Drummond Scientific Company, Catalog #2–000-001) were filled with liquid food by capillary action and inserted into the chamber through the pipette tips. Two tubes with liquid food were present in each chamber: one with 1 mM sucrose alone and the other with 1 mM sucrose and 10mM of an individual amino acid.
For the assay, 13 female and 2 male flies (all 7 days old) were introduced into the CAFÉ chamber, and starved overnight in a 25°C, 50% humidity-controlled room. Two capillary tubes were introduced the next morning, and flies were given four hours to ingest the liquid food. Both individual capillaries must have had at least 0.05μL consumed and a total consumption volume of 0.18μL for a PI calculation; only a small fraction of vials did not meet this criterion. Average values ± SEM are given.
For the assay, 13 female and 2 male flies (all 7 days old) were introduced into the CAFÉ chamber, and starved overnight in a 25°C, 50% humidity-controlled room. Two capillary tubes were introduced the next morning, and flies were given four hours to ingest the liquid food. Both individual capillaries must have had at least 0.05μL consumed and a total consumption volume of 0.18μL for a PI calculation; only a small fraction of vials did not meet this criterion. Average values ± SEM are given.
