Project description:We generated whole genome expression profiles from a homogeneous population of purified pacemaker neurons (ventral Lateral Neurons, LNvs) from wild type and clock mutant Drosophila. The study identifes a group of genes whose expression is highly enriched in LNvs compared to other neurons; and a second group of genes rhythmically expressed in LNvs in a clock-dependent manner. Drosophila larval brains (L3 stage) were taken from a 12:12hr light entrainment regime and dissected at ZT-3 or ZT-15. Larvae contained either Pdf-Gal4:UAS-GFP transgenes or Pdf-RFP to label the 8 LNvs pacemaker neurons per brain, allowing purification by flow cytometry. Brains were dissociated and LNvs purified by FACS, followed by RNA amplification and hybridization on Affymetrix microarrays.
Project description:While intensely studied in the context of synaptic plasticity, the interplay between electrical activity and transcription is also relevant to circadian pacemaker neurons where ~24hr rhythms in gene expression and neural activity define the functional state of clock neurons. Here we demonstrate broad transcriptional changes in Drosophila circadian pacemaker neurons (LNvs) in response to altered electrical activity, including a large set of circadian genes. We used microarrays to identify the global program of gene expression in purified Drosophila pacemaker neurons in response to targeted electrical manipulations
Project description:We generated whole genome expression profiles from a homogeneous population of purified pacemaker neurons (ventral Lateral Neurons, LNvs) from wild type and clock mutant Drosophila. The study identifes a group of genes whose expression is highly enriched in LNvs compared to other neurons; and a second group of genes rhythmically expressed in LNvs in a clock-dependent manner.
Project description:The innate immune response of insects relies on several humoral and cellular mechanisms that require the activation of circulating proteases in the hemolymph to be functional. Here, we analyzed the gelatinase and caseinase activities of Drosophila larval hemolymph under normal and pathogenic conditions (bacterial lipopolysaccharides or endoparasitoid Leptopilina boulardi) using in gel zymography. Gelatinase activity was more intense than caseinase activity and qualitative and quantitative variations were observed between D. melanogaster strains and Drosophila species. Mass spectrometry identified a large number of serine proteases in gel bands equivalent to the major gelatinase and caseinase bands and of these, the most abundant and redundant were Tequila and members of the Jonah and Trypsin protease families. However, hemolymph from Tequila null mutant larvae showed no obvious changes in zymographic bands. Nor did we observe any significant changes in hemolymph gelatinases activity 24 h after injection of bacterial lipopolysaccharides or after oviposition by endoparasitoid wasps. These data confirmed that many serine proteases are present in Drosophila larval hemolymph but those with gelatinase and caseinase activity may not change drastically during the immune response.
Project description:In Drosophila melanogaster larval hemolymph, under normal conditions, plasmatocytes and crystal cells represent respectively ~95% and ~5% of hemocytes, while lamellocytes, the third larval cell type, are absent since they are only induced after parasitoid wasp oviposition, their role being the encapsulation-melanization response to eliminate the wasp egg. However, even after induction lamellocytes number remains low, making difficult biochemical studies. Here using the D. melanogaster hopTum-l mutant that constitutively produces a high number of hemocytes, we set up a method to purify lamellocytes and analyzed their major proteins by 2D gel electrophoresis and their biotinylated plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry allowed to identify 430 proteins from the 2D spots and 344 from affinity purified proteins, totalizing 639 unique proteins. Known lamellocyte markers such as PPO3 and the integrin myospheroid are among the major proteins and affinity purification led to the detection of other integrins and a large array of integrins associated proteins involved in cell-cell junction formation and function. Overall newly identified proteins indicated that these cells are highly adapted to the encapsulation process but may have also several different physiological functions. This study provides the basis for new lamellocyte studies in vivo and in vitro, and develop markers to search whether different populations coexist, establish their origins and decipher their respective roles in drosophila physiology and immunity.
Project description:We produced bulk RNA sequencing data on Drosophila neurons, glia and hemocytes at embryonic and larval stages to extrapolate the most significant and specific features that identify a cell type as a whole. We also tracked changes in the expression in the two stages. We identified stable features that define a cell type functionally and developmentally as well as plastic features including stage-specific metabolic states, which likely depend on the environment.