@article {5482,
	title = {Tissue-specific activation of a single gustatory receptor produces opposing behavioral responses in Drosophila.},
	journal = {Genetics},
	volume = {192},
	year = {2012},
	month = {2012 Oct},
	pages = {521-32},
	abstract = {<p>Understanding sensory systems that perceive environmental inputs and neural circuits that select appropriate motor outputs is essential for studying how organisms modulate behavior and make decisions necessary for survival. Drosophila melanogaster oviposition is one such important behavior, in which females evaluate their environment and choose to lay eggs on substrates they may find aversive in other contexts. We employed neurogenetic techniques to characterize neurons that influence the choice between repulsive positional and attractive egg-laying responses toward the bitter-tasting compound lobeline. Surprisingly, we found that neurons expressing Gr66a, a gustatory receptor normally involved in avoidance behaviors, receive input for both attractive and aversive preferences. We hypothesized that these opposing responses may result from activation of distinct Gr66a-expressing neurons. Using tissue-specific rescue experiments, we found that Gr66a-expressing neurons on the legs mediate positional aversion. In contrast, pharyngeal taste cells mediate the egg-laying attraction to lobeline, as determined by analysis of mosaic flies in which subsets of Gr66a neurons were silenced. Finally, inactivating mushroom body neurons disrupted both aversive and attractive responses, suggesting that this brain structure is a candidate integration center for decision-making during Drosophila oviposition. We thus define sensory and central neurons critical to the process by which flies decide where to lay an egg. Furthermore, our findings provide insights into the complex nature of gustatory perception in Drosophila. We show that tissue-specific activation of bitter-sensing Gr66a neurons provides one mechanism by which the gustatory system differentially encodes aversive and attractive responses, allowing the female fly to modulate her behavior in a context-dependent manner.</p>
},
	issn = {1943-2631},
	doi = {10.1534/genetics.112.142455},
	author = {Joseph, Ryan M and Heberlein, Ulrike}
}
@article {5486,
	title = {Oviposition preference for and positional avoidance of acetic acid provide a model for competing behavioral drives in Drosophila.},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {106},
	year = {2009},
	month = {2009 Jul 7},
	pages = {11352-7},
	abstract = {<p>Selection of appropriate oviposition sites is essential for progeny survival and fitness in generalist insect species, such as Drosophila melanogaster, yet little is known about the mechanisms regulating how environmental conditions and innate adult preferences are evaluated and balanced to yield the final substrate choice for egg-deposition. Female D. melanogaster are attracted to food containing acetic acid (AA) as an oviposition substrate. However, our observations reveal that this egg-laying preference is a complex process, as it directly opposes an otherwise strong, default behavior of positional avoidance for the same food. We show that 2 distinct sensory modalities detect AA. Attraction to AA-containing food for the purpose of egg-laying relies on the gustatory system, while positional repulsion depends primarily on the olfactory system. Similarly, distinct central brain regions are involved in AA attraction and repulsion. Given this unique situation, in which a single environmental stimulus yields 2 opposing behavioral outputs, we propose that the interaction of egg-laying attraction and positional aversion for AA provides a powerful model for studying how organisms balance competing behavioral drives and integrate signals involved in choice-like processes.</p>
},
	keywords = {Acetic Acid, Animal, Animal Feed, Animals, Avoidance Learning, Biological, Brain, Drosophila melanogaster, Female, Hydrogen-Ion Concentration, Models, Neurons, Olfactory Pathways, Oviposition, Sexual Behavior, Taste},
	issn = {1091-6490},
	doi = {10.1073/pnas.0901419106},
	author = {Joseph, Ryan M and Devineni, Anita V and King, Ian F G and Heberlein, Ulrike}
}
