Mushroom body miscellanea: transgenic Drosophila strains expressing anatomical and physiological sensor proteins in Kenyon cells

Abstract

The fruit fly Drosophila melanogaster represents a key model organism for analyzing how neuronal circuits regulate behavior. The mushroom body in the central brain is a particularly prominent brain region that has been intensely studied in several insect species and been implicated in a variety of behaviors, e.g., associative learning, locomotor activity, and sleep. Drosophila melanogaster offers the advantage that transgenes can be easily expressed in neuronal subpopulations, e.g., in intrinsic mushroom body neurons (Kenyon cells). A number of transgenes has been described and engineered to visualize the anatomy of neurons, to monitor physiological parameters of neuronal activity, and to manipulate neuronal function artificially. To target the expression of these transgenes selectively to specific neurons several sophisticated bi- or even multipartite transcription systems have been invented. However, the number of transgenes that can be combined in the genome of an individual fly is limited in practice. To facilitate the analysis of the mushroom body we provide a compilation of transgenic fruit flies that express transgenes under direct control of the Kenyon-cell specific promoter, mb247. The transgenes expressed are fluorescence reporters to analyze neuroanatomical aspects of the mushroom body, proteins to restrict ectopic gene expression to mushroom bodies, or fluorescent sensors to monitor physiological parameters of neuronal activity of Kenyon cells. Some of the transgenic animals compiled here have been published already, whereas others are novel and characterized here for the first time. Overall, the collection of transgenic flies expressing sensor and reporter genes in Kenyon cells facilitates combinations with binary transcription systems and might, ultimately, advance the physiological analysis of mushroom body function.

Maturation of a central brain flight circuit in Drosophila requires Fz2/Ca2+ signaling

“…A reduction in the length of flight bouts was observed specifically upon knockdown of Dop1R2 in the α′, β ′ neurons ( Figure 7A ). The role of α′ β′ lobes, in flight was supported by another GAL4 driver, c305GAL4 , which expresses in the α′ β′ lobes and faintly in the γ lobe ( Krashes et al, 2007 ; Pech et al, 2013 ). Blocking synaptic activity or knockdown of Dop1R2 using c305aGAL4 resulted in significant flight deficits ( Figure 7—figure supplement 2 ).…”

“…This idea was tested by silencing specific MB neuropil lobes with mb186bGAL4 and mb247GAL4 drivers. mb186bGAL4 is a recently generated split GAL4 strain ( Aso et al, 2014 ) whose expression is restricted to the α′ β′ lobes ( Vogt et al, 2014 ), whereas mb247GAL4 is expressed in the α, β, and γ lobes ( Zars, 2000 ; Krashes et al, 2007 ; Pech et al, 2013 ). Synaptic release in MB neurons of adult flies was inhibited by expression of a temperature sensitive dominant negative dynamin transgene ( UAS-Shi ts ) under control of either mb186bGAL4 or mb247GAL4 drivers.…”

Dynamic labelling of neural connections in multiple colours by trans-synaptic fluorescence complementation

“…We expressed the syb:spGFP1–10 construct in two to three olfactory PNs (under the control of R68D02-LexA , also driving the red fluorescent protein tdTomato, Fig. 2 ), while CD4:spGFP11 was driven by a promoter active in a large subset of Kenyon cells ( MB247-Gal4 (refs 18 , 19 )). In this set-up, the axons of the PNs expressing syb:spGFP1–10 traverse the Calyx, a dense neuropil comprised of the dendrites of ∼2,000 Kenyon cells expressing the broadly localized CD4:spGFP11, before proceeding to terminate within the lateral horn (LH; Fig.…”

Glial lipid droplets and neurodegeneration in a Drosophila model of complex I deficiency

“…Mushroom bodies are an associative area into the central brain controlling complex behaviors such as locomotion or learning and memory (Crittenden, Skoulakis, Han, Kalderon, & Davis, 1998) and are highly vulnerable in Drosophila models of neurodegenerative diseases (Agrawal et al, 2005). Axonal projections of the mushroom body form distinct lobes, which could be evidenced by FasII immunostaining (Pech et al, 2013). As illustrated in Figure 3e…”