Biology subjects

Dionne, H.

Publications and source records attributed to Dionne, H..

6 recordsLinked to original sources

bioRxiv2024

A split-GAL4 driver line resource for Drosophila CNS cell types

Techniques that enable precise manipulations of subsets of neurons in the fly central nervous system have greatly facilitated our understanding of the neural basis of behavior. Split-GAL4 driver lines allow specific targeting of cell types in Drosophila melanogaster and other species. We describe here a collection of 3060 lines targeting a range of cell types in the adult Drosophila central nervous system and 1373 lines characterized in third-instar larvae. These tools enable functional, transcriptomic, and proteomic studies based on precise anatomical targeting. NeuronBridge and other search tools relate light microscopy images of these split-GAL4 lines to connectomes reconstructed from electron microscopy images. The collections are the result of screening over 77,000 split hemidriver combinations. Previously published and new lines are included, all validated for driver expression and curated for optimal cell type specificity across diverse cell types. In addition to images and fly stocks for these well-characterized lines, we make available 300,000 new 3D images of other split-GAL4 lines.

neuroscience↗

bioRxiv2021

Synergy of color and motion vision for detecting approaching objects in Drosophila

Color and motion are used by many species to identify salient moving objects. They are processed largely independently, but color contributes to motion processing in humans, for example, enabling moving colored objects to be detected when their luminance matches the background. Here, we demonstrate an unexpected, additional contribution of color to motion vision in Drosophila. We show that behavioral ON-motion responses are more sensitive to UV than for OFF-motion, and we identify cellular pathways connecting UV-sensitive R7 photoreceptors to ON and OFF-motion-sensitive T4 and T5 cells, using neurogenetics and calcium imaging. Remarkably, the synergy of color and motion vision enhances the detection of approaching UV discs, but not green discs with the same chromatic contrast, and we show how this generalizes for visual systems with ON and OFF pathways. Our results provide a computational and circuit basis for how color enhances motion vision to favor the detection of saliently colored objects.

neuroscience↗

bioRxiv2021

Synaptic targets of functionally specialized R7 and R8 photoreceptors in the central eye and dorsal rim area of Drosophila

Color and polarization provide complementary information about the world and are detected by specialized photoreceptors. However, the downstream neural circuits that process these distinct modalities are incompletely understood in any animal. Using electron microscopy, we have systematically reconstructed the synaptic targets of the photoreceptors specialized to detect color and skylight polarization in Drosophila, and we have used light microscopy to confirm many of our findings. We identified known and novel downstream targets that are selective for different wavelengths or polarized light, and followed their projections to other areas in the optic lobes and the central brain. Our results revealed many synapses along the photoreceptor axons between brain regions, new pathways in the optic lobes, and spatially segregated projections to central brain regions. Strikingly, photoreceptors in the polarization-sensitive dorsal rim area target fewer cell types, and lack strong connections to the lobula, a neuropil involved in color processing. Our reconstruction identifies shared wiring and modality-specific specializations for color and polarization vision, and provides a comprehensive view of the first steps of the pathways processing color and polarized light inputs.

neuroscience↗

bioRxiv2020

Spatiotemporal Control of Pathway Sensors and Cross-Pathway Feedback Regulate a Cell Differentiation MAPK Pathway in Yeast

Mitogen-Activated Protein Kinase (MAPK) pathways control cell differentiation and the response to stress. MAPK pathways can share components with other pathways yet induce specific responses through mechanisms that remain unclear. In Saccharomyces cerevisiae, the MAPK pathway that controls filamentous growth (fMAPK) shares components with the MAPK pathway that regulates the response to osmotic stress (HOG). By exploring temporal regulation of MAPK signaling, we show here that the two pathways exhibited different patterns of activity throughout the cell cycle. The different patterns resulted from different expression profiles of genes encoding the mucin sensors (MSB2 for fMAPK and HKR1 for HOG). We also show that positive feedback through the fMAPK pathway stimulated the HOG pathway, presumably to modulate fMAPK pathway activity. By exploring spatial regulation of MAPK signaling, we found that the shared tetraspan protein, Sho1p, which has a dynamic localization pattern, induced the fMAPK pathway at the mother-bud neck. A Sho1p-interacting protein, Hof1p, which also localizes to the mother-bud neck and regulates cytokinesis, also regulated the fMAPK pathway. Therefore, spatial and temporal regulation of pathway sensors, and cross-pathway feedback, regulate a MAPK pathway that controls a cell differentiation response in yeast.

cell biology↗

bioRxiv2018

Neurogenetic dissection of the Drosophila innate olfactory processing center

Animals exhibit innate behaviours in response to a variety of sensory stimuli such as olfactory cues. In Drosophila, a higher olfactory centre called the lateral horn (LH) is implicated in innate behaviour. However, our knowledge of the structure and function of the LH is scant, due to the lack of sparse neurogenetic tools for this brain region. Here we generate a collection of split-GAL4 driver lines providing genetic access to 82 LH cell-types. We identify the neurotransmitter and axo-dendritic polarity for each cell-type. Using these lines were create an anatomical map of the LH. We found that [~]30% of LH projections converge with outputs from the mushroom body, the site of olfactory learning and memory. Finally, using optogenetic activation of small groups of LH neurons. We identify cell-types that drive changes in either valence or specific motor programs, such as turning and locomotion. In summary we have generated a resource for manipulating and mapping LH neurons in both light and electron microscopy and generated insights into the anatomy and function of the LH.

neuroscience↗

bioRxiv2017

Genetic reagents for making split-GAL4 lines in Drosophila

The ability to reproducibly target expression of transgenes to small, defined subsets of cells is a key experimental tool for understanding many biological processes. The Drosophila nervous system contains thousands of distinct cell types and it has generally not been possible to limit expression to one or a few cell types when using a single segment of genomic DNA as an enhancer to drive expression. Intersectional methods, in which expression of the transgene only occurs where two different enhancers overlap in their expression patterns, can be used to achieve the desired specificity. This report describes a set of over 2,800 transgenic lines for use with the split-GAL4 intersectional method.

neuroscience↗