Neural architecture of the primary gustatory center of Drosophila melanogaster visualized with GAL4 and LexA enhancer‐trap systems

Abstract

Gustatory information is essential for animals to select edible foods and avoid poisons. Whereas mammals detect tastants with their taste receptor cells, which convey gustatory signals to the brain indirectly via the taste sensory neurons, insect gustatory receptor neurons (GRNs) send their axons directly to the primary gustatory center in the suboesophageal ganglion (SOG). In spite of this relatively simple architecture, the precise structure of the insect primary gustatory center has not been revealed in enough detail. To obtain comprehensive anatomical knowledge about this brain area, we screened the Drosophila melanogaster GAL4 enhancer-trap strains that visualize specific subsets of the gustatory neurons as well as putative mechanosensory neurons associated with the taste pegs. Terminals of these neurons form three branches in the SOG. To map the positions of their arborization areas precisely, we screened newly established LexA::VP16 enhancer-trap strains and obtained a driver line that labels a large subset of peripheral sensory neurons. By double-labeling specific and landmark neurons with GAL4 and LexA strains, we were able to distinguish 11 zones in the primary gustatory center, among which 5 zones were identified newly in this study. Arborization areas of various known GRNs on the labellum, oesophagus, and legs were also mapped in this framework. The putative mechanosensory neurons terminate exclusively in three zones of these areas, supporting the notion of segregated primary centers that are specialized for chemosensory and mechanosensory signals associated with gustatory sensation.

Involvement of the drosophila taurine/aspartate transporter dEAAT2 in selective olfactory and gustatory perceptions

“…Elav is a RNA binding protein specifically expressed in most postmitotic neurons (Robinow and White, 1991;Ito and Hotta, 1992). According to previous studies (Miyasaki and Ito, 2010), the antibody used in this study labeled nuclei of the neurons located in all cortical regions of the brain and in peripheral regions. 2.…”

Motor control of fly feeding

“…Gustatory information from different body parts might in some cases remain segregated into at least the first interneuron layer, since taste receptors from different body parts project to distinct regions in the nervous system in several insect species (Stocker 1994, Mitchell et al 1999, Wang et al 2004, Jørgensen et al 2006, Miyazaki and Ito 2010, Kwon et al 2014. Different taste modalities (e.g.…”

Identification of neurons responsible for feeding behavior in the Drosophila brain

“…The SOG region is widely regarded as the primary taste center in flies, and receives information from the sensory neurons and sends signals to control feeding movement after local circuit processing [31,54]. In recent years, although much progress has been made in identifying first-order sensory neurons and motor neurons controlling feeding movement, a direct connection between the two neuronal populations has not been reported, which suggests that there is at least a one-step relay mediated by interneurons in the SOG [31,32].…”