Biology subjects

Brueckner, K.

Publications and source records attributed to Brueckner, K..

4 recordsLinked to original sources

bioRxiv2021

Fly Cell Atlas: a single-cell transcriptomic atlas of the adult fruit fly

The ability to obtain single cell transcriptomes for stable cell types and dynamic cell states is ushering in a new era for biology. We created the Tabula Drosophilae, a single cell atlas of the adult fruit fly which includes 580k cells from 15 individually dissected sexed tissues as well as the entire head and body. Over 100 researchers from the fly community contributed annotations to >250 distinct cell types across all tissues. We provide an in-depth analysis of cell type-related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types that are shared between tissues, such as blood and muscle cells, allowed the discovery of rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the entire Drosophila community and serves as a comprehensive reference to study genetic perturbations and disease models at single cell resolution.

genomics↗

bioRxiv2020

Dscam1 promotes blood cell survival in Drosophila melanogaster through a dual role in blood cells and neurons

Down Syndrome Cell Adhesion Molecule 1 (Dscam1) is a receptor-like cell adhesion molecule that is conserved across the animal kingdom, but its roles in hematopoiesis remain unknown. Dscam1 related genes in vertebrates and invertebrates are key regulators of neuron morphogenesis and neuronal tiling. In Drosophila, Dscam1 in addition has roles in blood cells (hemocytes) in innate immunity and phagocytosis of pathogens. Given the anatomical and functional role of peripheral sensory neurons as microenvironments for resident hematopoietic sites in the Drosophila larva, we sought to investigate the role of Dscam1 in this context. Interestingly, we find that Dscam1 fills the role of a previously anticipated factor in neuron-hemocyte communication that supports trophic survival: tissue specific silencing of Dscam1 by in vivo RNAi in sensory neurons leads to neuron reduction, which in turn results in reduced hemocyte numbers due to apoptosis. Dscam1 silencing in hemocytes also results in a reduction of hemocytes and increased apoptosis. This cell-autonomous effect of Dscam1 silencing can be mimicked by RNAi silencing of dreadlocks (dock), suggesting that intracellular Dscam1 signaling relies on the adapter protein Dock in this system. Our findings reveal a dual role for Dscam1 in Drosophila hematopoiesis, by promoting survival of the sensory neuron microenvironments that in turn support hemocyte survival, and by promoting survival of hemocytes cell-autonomously. It will be interesting to explore possible functions of vertebrate Dscam1 related genes such as DSCAML1 in blood cells and their trophic survival.

developmental biology↗

bioRxiv2020

Regulation of blood cell transdifferentiation by oxygen sensing neurons in Drosophila

Transdifferentiation generates specialized cell types independent of stem or progenitor cells. Despite the unique process, it remains poorly understood how transdifferentiation is regulated in vivo. Here we reveal a mechanism of environmental control of blood cell transdifferentiation in a Drosophila model of hematopoiesis. Functional lineage tracing provides evidence for transdifferentiation from macrophage-like plasmatocytes to crystal cells that execute melanization. Interestingly, this transdifferentiation is promoted by neuronal activity of a specific subset of sensory neurons, in the caudal sensory cones of the larva. Crystal cells develop from plasmatocyte clusters surrounding the sensory cones, triggered by environmental conditions: oxygen sensing, and the atypical guanylyl cyclase Gyc88E specifically expressed in the sensory cone neurons, drive plasmatocyte-to-crystal cell transdifferentiation. Our findings reveal an unexpected functional and molecular link of environment-monitoring sensory neurons that govern blood cell transdifferentiation in vivo, suggesting similar principles in vertebrate systems where environmental sensors and blood cell populations coincide. HighlightsO_LIFunctional lineage tracing reveals in vivo transdifferentiation in a Drosophila model of hematopoiesis C_LIO_LIActive sensory neurons of the caudal sensory cones promote blood cell transdifferentiation in the Drosophila larva C_LIO_LIEnvironmental oxygen sensing and atypical guanylyl cyclase activity in sensory cone neurons drive blood cell transdifferentiation C_LI

developmental biology↗

bioRxiv2019

Blood cells of adult Drosophila do not expand, but control survival after bacterial infection by induction of Drosocin around their reservoir at the respiratory epithelia

Drosophila melanogaster has been an excellent model for innate immunity, but the role and regulation of adult blood cells and organismal immunity have remained incompletely understood. Here we address these questions in a comprehensive investigation of the blood cell system in adult Drosophila. As a central finding, we reveal the largest reservoir of blood cells (hemocytes) at the respiratory epithelia (tracheal air sacs) and fat body of the thorax and head. We show that most hemocytes of adult Drosophila are phagocytic macrophages (plasmatocytes), derived by more than 60% from the embryonic lineage that parallels vertebrate tissue macrophages. Surprisingly, in contrast to hemocytes at the larval stage, we find no capacity of the adult blood cell system to expand. Instead, we demonstrate its central role in relaying an innate immune response to tissues surrounding the blood cell reservoir: Hemocytes, through Imd signaling and the Jak/Stat pathway ligand Upd3, act as sentinels of bacterial infection that induce expression of the antimicrobial peptide gene Drosocin in the respiratory epithelia and colocalizing domains of the fat body. We demonstrate that endogenous Drosocin expression in these tissues promotes animal survival after bacterial infection. Our work identifies the first molecular step in a new relay of organismal immunity, establishing adult Drosophila as model to dissect mechanisms of inter-organ immunity.

immunology↗