A neuromodulatory mechanism for state-dependent nutrient detection in Drosophila [thesis]

Habibe Üçpunar
2017
Feeding is an essential routine of an animal to survive. The decision of what to eat is a collective outcome of a sensory evaluation and its nutritional needs. While an animal may decide to eat food just because of its good taste, it is also possible that nutritional needs dictate what to eat through appetite or cravings. Pregnant females often report cravings that potentially arise from a dramatic change in their nutritional needs and physiological and hormonal state. Food sources attract the
more » ... ources attract the attention of many animals primarily by their smell (long range cue) and taste (short range cue). Those sensory cues help these animals to identify a food source and they use them to assess the nutritional value of the food. Due to changing internal needs, animals often make different choices elicited by the same chemosensory cue bouquet. However, little is known how exactly internal needs of an animal modulate its perception and its sensory systems. In this cumulative thesis, I present two published studies addressing this question by using an important class of nutrients, the polyamines. In the first study, I, in collaboration with colleagues, investigated polyamines as chemosensory cues and found that they are detected by both olfactory and gustatory systems of Drosophila as signals for beneficial food or egg laying sites. This multimodal polyamine detection is mediated by an ionotropic receptor, IR76b, along with a co-receptor (IR41a) in the olfactory system and by IR76b alone, or with a yet to be identified co-receptor, in the gustatory system. Moreover, female flies significantly increase their reproductive success if they are fed with polyamine enriched food. This finding has provided an entry point to the second paper, in which the role of the mating state in the perception of polyamines has been investigated. Surprisingly, mated female flies exhibit an enhanced attraction towards biologically relevant concentrations of polyamines. This finding is particularly interesting because the modulation takes place right at t [...]
doi:10.5282/edoc.21235 fatcat:zr2wyspogvgp5ptjw7j24afxau