Eline thermal nociceptive responses (Figure 1E). Next, we tested 5714-73-8 Data Sheet UV-induced nociceptive sensitization. Pan-neuronal knockdown of dTk significantly lowered thermal allodynia (responsiveness to sub-threshold 38 ) (Figure 1F and Figure 1– figure supplement five). Two non-overlapping RNAi transgenes (TkJF01818 and TkKK112227) targeting Tachykinin decreased the allodynia response from 70 to about 20 when compared with relevant GAL4 or UAS alone controls 24 hr soon after UV irradiation (Figure 1F). Consistent with all the absence of DTK staining in class IV neurons (Figure 1–figure supplement 1), class IV-specific knockdown of dTk didn’t alter thermal allodynia (Figure 1F). As genetic confirmation on the RNAi phenotype, we tested mutant alleles of dTk for tissue damage-induced thermal allodynia. Heterozygous larvae bearing these dTk alleles, which includes a deficiency spanning the dTk locus, displayed regular thermal allodynia (Figure 1G). By contrast, all homozygous and transheterozygous combinations of dTk alleles drastically reduced thermal allodynia (Figure 1G). For that reason, we conclude that Tachykinin is necessary for the development of thermal allodynia in response to UV-induced tissue harm.Tachykinin Receptor is required in class IV nociceptive sensory neurons for thermal allodyniaTwo GPCRs recognize Tachykinins. DTKR (TkR99D or CG7887) recognizes all six DTKs (Birse et al., 2006) whereas NKD (TkR86C or CG6515) binds DTK-6 plus a tachykinin-related peptide, natalisin (Jiang et al., 2013; Monnier et al., 1992; Poels et al., 2009). Simply because DTKR binds much more broadly to DTKs, we tested if class IV neuron-specific knockdown of dtkr working with the ppk-GAL4 driver (Ainsley et al., 2003) led to defects in either baseline Quinocetone-D5 Purity & Documentation nociception or thermal allodynia. See Figure 2A to get a schematic on the dtkr locus as well as the genetic tools applied to assess this gene’s part in thermal allodynia. Similar to dTk, no baseline nociception defects had been observed upon knockdown of dtkr (Figure 2B). Larvae homozygous for TkR99Df02797 and TkR99DMB09356 were also normal for baseline nociceptive behavior (Figure 2C). Although baseline nociception was unaffected, class IV neuron-specific expression of UASdtkrRNAi considerably decreased thermal allodynia in comparison with GAL4 or UAS alone controls (Figure 2D and Figure 2–figure supplement 1). This reduction was rescued upon simultaneous overexpression of DTKR using a UAS-DTKR-GFP transgene, suggesting that the RNAi-mediatedIm et al. eLife 2015;4:e10735. DOI: 10.7554/eLife.5 ofResearch articleNeuroscienceFigure 2. Tachykinin Receptor is expected in class IV nociceptive sensory neurons for thermal allodynia. (A) Schematic from the dtkr genomic locus. Place of transposon insertion alleles and targeted sequences of UASRNAi transgenes are shown. (B,C) Baseline thermal nociception at 45 and 48 . (B) dtkr RNAi in class IV neurons and controls. (C) dtkr mutant alleles and controls. (D,E) UV-induced thermal allodynia at 38 . (D) dtkr RNAi and rescue in class IV neurons. (E) dtkr mutant alleles and controls. (F) “Genetic” thermal allodynia inside the absence of injury upon overexpression of DTKR in class IV neurons. (G ) Dissected larval epidermal wholemounts (genotype: ppkDTKR-GFP) immunostained with anti-LemTRP-1 (reacts to DTKs) and anti-GFP. (G) DTKR-GFP expression in class IV neuron soma and dendrites. (H) Larval brain wholemount. GFP (green); anti-DTK (magenta). Yellow Box indicates close-up shown in I. (I) Axonal tracts expressing DTKR-GFP in class IV neurons juxt.