Project description:Analysis of differential gene expression in third instar Drosophila salivary glands in the absence versus presence of cohesin. ABSTRACT: Developmental abnormalities observed in Cornelia de Lange Syndrome (CdLS) have been genetically linked to mutations in the cohesin machinery. These findings raise the possibility that cohesin, in addition to its canonical function of mediating sister chromatid cohesion, might also be involved in regulating gene expression. We report that cleavage of cohesinM-CM-^Us kleisin subunit in post-mitotic Drosophila salivary glands induces major changes (both up and down) in the transcript levels of many genes. Kinetic analyses of changes in transcript levels upon cohesin cleavage reveal that a subset of genes responds to cohesin cleavage within a few hours. In addition, cohesin binds to most of these loci, suggesting that cohesin is directly regulating their expression. Amongst these genes are several that are regulated by the steroid hormone Ecdysone. Transcripts at EcR and Eip74EF, which encode an Ecdysone Receptor and an Ecdysone-regulated transcription factor, respectively, decline ten-fold within four hours of cohesin cleavage. Cytological visualization of transcription at selected Ecdysone-responsive genes reveals that puffing at Eip74EF ceases within an hour or two of cohesin cleavage, long before any decline in EcR associated with this locus. We conclude that cohesin regulates expression of a distinct set of genes, including those mediating the Ecdysone response. A heat-inducible transgene (hs-TEV) was used to induce TEV in terminally differentiated third instar Drosophila salivary glands expressing either wild type (+ cohesin) or TEV-cleavable myc10-tagged Rad21 protein (Rad21TEV, - cohesin). Total RNA was isolated from + and - cohesin salivary glands 10-12 hours after heat shock induction of TEV (7 independent biological samples each). RNA samples were converted to cDNA, labeled with Cy3 and Cy5 respectively (3x) and vice versa (4x; dye swaps), and hybridized to INDAC FL003 arrays. Analysis of seven arrays, each hybridized to an independently generated sample-pair revealed major differences in transcript levels between + and - cohesin samples.

Project description:The early stages of the immune response against aberrant tissues such a tumors are technically difficult to study and therefore little understood. To analyze the innate immune response towards modified self-tissue we expressed a dominant-active version of the Ras oncogene in Drosophila imaginal discs and salivary glands. Signs of an immune response are observed on wings of adult flies, which show spots of melanization and in larvae, where the salivary glands attract blood cells. In line with the strong response mounted against salivary glands, they are found to express metalloproteases and apoptotic markers making them both accessible and recognizable for the immune system. The response against the glands bears several hallmarks of an encapsulation response including flattening of plasmatocytes, differentiation of lamellocytes, attachment of crystal cells and melanization at the final stage. RNA sequencing of the fat body, the primary producer of immune effectors, reveals a pattern of induced genes, which overlaps the one previously found upon wasp infestation but shows also several specific features. Evidence for the functional importance of one of the induced genes is presented proving the power of our approach to identify regulators of the response against modified self. Transcriptome analysis of the immune response in the fat body after expression of dominant-active RAS in the wing imaginal discs and salivary glands. Comparison of fat bodies from 3 control and 3 RAS-expressing larvae. For each sample fat bodies from 40 individuals were dissected. Differential gene expression files [output of Cuffdiff] are linked below: ResultsContr123vsRas123Individual.xls: Output file of Cuffdiff. Differential gene expression analysis, three control compared to individual Ras induced; replicate analysis using Cuffdiff. ResultsContr123vsRas123Multiple.xls: Output file of Cuffdiff. Differential gene expression analysis, three control compared to three Ras induced; replicate analysis using Cuffdiff. ResultsContr123vsRas12Multiple.xls: Output file of Cuffdiff. Differential gene expression analysis, three control compared to two Ras induced; replicate analysis using Cuffdiff.

Project description:When misexpressed in late Drosophila prepupae, the transcription factor Senseless (Sens) blocks death of the larval salivary glands that normally occurs in the early pupa. The aim of the experiment was to identify genes responding to Sens that might mediate the effect of the protein on cell death and other biological processes. The yeast transcription factor GAL4, expressed from a heat-inducible transgene (P{GAL4-Hsp70.PB}89-2-1), was used to drive expression of Sens from a UAS-sens transgene. After crossing the GAL4 and UAS lines, expression of GAL4 was induced by a 30-min heat shock treatment (37 Â°C) of the progeny at 9 hours after puparium formation. Salivary glands were dissected at 14 hours after puparium formation and RNA isolated for microarray analysis with Affymetrix GeneChips. Control samples were obtained from animals treated the same way carrying one copy of the GAL4 transgene (progeny of a cross between flies of the P{GAL4-Hsp70.PB}89-2-1 and w1118 strains) and w1118 animals. The microarray data identified several genes associated with programmed cell death, including caspase genes, which respond to Sens. In addition, the data show that many Drosophila genes respond to the yeast transcription factor GAL4 in a UAS-independent manner. To identify target genes of Sens that are of biological relevance, gene expression patterns in the presence of Sens were compared to gene expression patterns in both the presence and the absence of GAL4. This comparison revealed that Sens seems to preferentially downregulate targets that are upregulated by GAL4, suggesting that these genes may not necessarily constitute true transcriptional targets of Sens. Experiment Overall Design: Experimental RNA samples were obtained in 3 biological replicates from sens-expressing salivary glands (SG_sens_14APF_rep1, SG_sens_14APF_rep2, SG_sens_14APF_rep3) and compared to control samples obtained from GAL4-expressing salivary glands (SG_1P{hsGAL4}89(S)_14APF_rep1) and non-GAL4-expressing salivary glands (SG_w1118_14APF_rep1, SG_w1118_14APF_rep2). All samples were compared using dChip and normalized to the same baseline array (median intensity 150).

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Drosophila melanogaster

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