Ir56b is an atypical ionotropic receptor that underlies appetitive salt response in Drosophila

Taste coding of heavy metal ion-induced avoidance in Drosophila

“…Previous reports evaluated responses of flies to HMIs at mM levels. 21 , 26 , 27 , 31 In our results, the avoidance response to most of the trace elements increased with concentration and peaked at 2 mM ( Figures S1 C–S1G). In our test, flies exhibited no preference to Na + at 2 mM, which is beyond the known effective range.…”

“…GRNs in flies are well-known for being responsible for the detection of different classes of compounds, including sweet compounds ( Gr64f + and Gr5a + neurons), bitter compounds ( Gr66a + , Gr32a + , and Gr33a + neurons), 20 , 35 salt ( Ir76b + neurons), 26 , 31 amino acids ( Gr66a + neurons, Ir76b + and Ir25a + neurons), 25 , 36 fatty acids ( Ir56d + and Gr64f + neurons), 23 , 24 and acetic acid and lactic acid ( Gr66a + and Gr64f + neurons). 37 , 38 , 39 We set out to identify the GRNs responsible for detecting HMIs, using a selective inhibition approach by overexpressing Kir2.1, an inward-rectifying potassium ion channel, to hyperpolarize the targeted neurons.…”

Optogenetic induction of appetitive and aversive taste memories in Drosophila

“…The enhancement of salt palatability following co-incident activation of sweet taste may be surprising, given that NaCl on its own activates sweet GRNs (Jaeger et al, 2018; Marella et al, 2006). However, salt activates only about one third of sweet GRNs (Dweck et al, 2022), and thus appetitive memory formation may be driven by strong activation of the broader sweet neuron population. Nevertheless, directly stimulating DANs as the flies experienced taste inputs through feeding afforded us the ability to reduce this complication and also interrogate the roles of specific DAN populations.…”

Alkaline taste sensation through the alkaliphile chloride channel in Drosophila

“…3i) 15,56 or Ir76bexpressing GRNs involved in the taste sensations of low concentrations of salt (Fig. 3j) 16,18 and other substances 57 . Furthermore, the alka-expressing GRNs exhibited no obvious overlap with other types of GRNs, such as ppk28-expressing GRNs responsible for detecting water (Fig.…”

“…Like mammals, the fruit fly, Drosophila melanogaster, employs different classes of taste receptors to detect sugars [11][12][13][14][15] , salts [16][17][18] , acids 6,[19][20][21] , bitter substances 22,23 , and other chemicals [24][25][26][27][28][29] . Given that flies have such a remarkable capability to detect a wide range of substances through taste, we inferred that flies are also able to sense the alkalinity of food.…”