Skip to main content
. 2013 Sep 12;9(9):e1003710. doi: 10.1371/journal.pgen.1003710

Figure 2. Fatty acids are appetitive tastants.

Figure 2

A) Left: Capillary feeding assay CAFE provides flies a choice between a nutrient and control tube. Right: In Proboscis extension reflex (PER) assay, flies are stimulated with a tastant on their feet and they respond with extension of their proboscis to appetitive substances in attempt to feed. The probability of their response is proportional to the level of starvation and the hedonic value of the substance. B) HxA, OcA, LiA acids are preferred over water in CAFE at concentrations ranging from 1–0.1%. C) The PER elicited in response to presentation of HxA or OcA. Concentrations of 1% to 0.01% elicit significant PER responses that are concentration dependent. D) Poxn mutants lack all peripheral taste neurons and show no response to HxA, fructose, sucrose or yeast. E) Appetitive response to FAs in two-choice feeding assay is comparable to low concentrations of sugars and is concentration dependent. Intake of 0.4% HxA and 0.4% OcA were measured against different concentrations of sucrose. Flies prefer sucrose to water at concentrations of 0.5 mM or greater but prefer 0.4% HxA and 0.4% OcA to 1 mM sucrose or lower, while sucrose is preferred at concentrations of 2 mM and greater (p<0.001). All data, mean ± s.e.m. ** p<0.01, *** p<0.001; NS, not significant, t-test.