Trends in Genetics
ReviewDrosophila Chemoreceptors: A Molecular Interface Between the Chemical World and the Brain
Section snippets
The Problem
Animals in their natural environments are immersed in a sea of chemical compounds. Some of these compounds signal the presence of nutrients, while others signify the danger of poisons. Some compounds indicate the proximity of a mating partner, while others warn of a predator. Animals must be able to detect and identify a wide variety of meaningful signals among the vast complexity of their chemical milieu.
In addition to chemical identity, chemical intensity can also be critical to an animal.
The Cellular Context of Chemoreception
Volatile compounds are sensed by olfactory receptor neurons (ORNs) of the olfactory system, whereas non-volatile compounds are detected by gustatory receptor neurons (GRNs) of the taste system. However, the conceptual wall dividing olfaction and taste has been increasingly assaulted by a barrage of experimental results that establish new links between the two sensory modalities.
The Largest Families of Chemoreceptors
Chemoreceptors of the fly are numerous and sundry (Figure 4). A recurrent source of excitement in the field has been the discovery of new kinds of chemoreceptors. Below we describe the largest classes of chemoreceptors. We also introduce some additional classes of chemoreceptors in Box 2. Other kinds of receptors may well lurk in the genome of the fly, awaiting discovery.
Concluding Remarks and Future Perspectives
Great progress has been made in understanding the receptors that constitute the basis of all of chemosensory perception. However, critical boxes remain black, key principles remain controversial, and major topics remain unexplored (see Outstanding Questions). It is as if a new continent has been discovered but only the coastline has been mapped.
Ors and Grs are currently represented as squiggles through cartoon membranes, with much uncertainty in the case of Grs. A 3D structure of Ors and Grs
Acknowledgments
The authors thank Karen Menuz and Zhe He for helpful comments. They apologize to those whose work has not been cited due to space constraints or amnesia. Their work is supported by an NRSA (R.M.J.) and grants (J.R.C.) from the NIH.
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