indicating that PERK re accumulation was still MEK dependent

odorants are detected BAM7 by olfactory receptor neurons housed in the sensillon the third antennal segment and on the maxillary palps. Each receptor neuron expresses one odorant receptor genes out of pool of 60 G protein coupled receptors. All ORNs expressing the same receptor converge, in general, to one glomerulus in the antennal lobe. AL glomeruli are also innervated by at least two populations of local interneurons, and by projection neurons. While the role of the LNs in the processing of odor information is still under debate, it is known that PNs carry olfactory information to higher brain centers, such as the mushroom bodies and the lateral protocerebrum. To investigate the detection properties of the ORNs and to understand how odor information is processed in the fly brain, we have used the Gal4UAS system to express the calcium detector GcAMP in different neuron populations along the olfactory pathway. We measured Retroperitoneal lymph node dissection odor evoked calcium responses in ORNs that express the olfactory receptor Or22aiming at comprehensive characterization of its molecular receptive range. We screened the responses to 104 odors both at the level of the sensory transduction on the antennand of the neuronal transmission in the AL. At 10?2 dilution, 39 odors elicited at least half maximal response. For these odorants we established dose response relationships over their entire dynamic range. Ethyl hexanoate and methyl hexanoate were the best stimuli, eliciting consistent responses at dilutions as low as 9. We found no differences between the antennal and the AL MRR. Our results show that Or22has broad yet selective MRR, and can be functionally described both as specialist and generalist regarding its ecological NSC-66811 role in odor detection. Next, we investigated odor coding at population level. We analyzed the representation of three odors across wide concentration range within four different neuron populations innervating the AL. ORNs were labeled by means of Gal4 line driven by the promoting region of Or83b, two distinct LN populations were labeled using two enhancer trap lines provided by Dr. Kei Ito and PNs were labeled using an enhancer trap line generated by Dr. Gertrud Heimbeck. Our datshow that, in general, higher concentrations induced increases in response amplitude and also in the number of responding glomeruli. In most cases, the sensitivity of PNs was comparable to that of ORNs, while that of the LN was shifted to higher concentrations. The dynamic range of ORNs and PNs was also broader than that of LNs. When comparing the two different LN subpopulations, differences in the spatial distribution of the responses as well as differences in their temporal dynamic were found.