Drosophila gene expression in response to the botanical insecticide Piper nigrum
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
SUBMITTER: Helen Jensen
PROVIDER: E-GEOD-3032 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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2010-06-11 | E-GEOD-3033 | biostudies-arrayexpress
Project description:Enteric pathogens have developed several resistance mechanisms to survive the antimicrobial action of bile. We investigated the transcriptional profile of Vibrio cholerae O1 El Tor strain C6706 under virulence gene inducing conditions, in the presence and absence of bile. Microarray analysis revealed that the expression of 119 genes was affected by bile. The mRNA levels of genes encoding proteins involved in transport was increased in the presence of bile, whereas mRNA levels of genes encoding proteins involved in pathogenesis and chemotaxis was decreased. This study identified genes encoding transcriptional regulators from the TetR family (vexR and breR) and multidrug efflux pumps from the RND superfamily (vexB and vexD [here renamed breB]) that were induced in response to bile. Further analysis regarding vexAB and breAB expression in the presence of various antimicrobial compounds established that vexAB was induced in the presence of bile, SDS or novobiocin, whereas induction of breAB was specific to bile. BreR is a direct repressor of the breAB promoter and is able to autoregulate its own expression, as demonstrated by transcriptional and electrophoretic mobility shift assays (EMSA). Expression of breR and breAB is induced in the presence of the bile salts cholate, deoxycholate or chenodeoxycholate and EMSA showed that deoxycholate is able to abolish formation of BreR-PbreR complexes. We propose that deoxycholate is able to interact with BreR and induce a conformational change that will interfere with its DNA binding ability resulting in breAB and breR expression. These results provide new insight into a transcriptional regulator and a transport system that likely play an essential role in the ability of Vibrio cholerae to resist the action of bile in the host. Keywords: Vibrio cholerae response to bile Three independent experiments were performed for the microarray analysis. From each experiment, RNA was obtained from four different time points and was prepared for hybridization, therefore, a total of 3 slides were analyzed per time point. The growth conditions were as follows; C6706 str2 was grown 15 h in LB medium at 30 degrees C with aeration. The cultures were then diluted 100-fold into AKI medium with, or without, 0.4% crude bile (high bile concentration) and were grown at 37degrees C for 3.5 h stationary followed by 2 h with aeration to induce virulence gene expression. Then the cultures were diluted 100-fold into AKI medium with, or without, 0.02% crude bile (low bile concentration) and were grown at 37 degrees C for 2 h stationary. Samples were obtained from 4 different time points: 2, 4, and 5.5 h from the high bile cultures, and at 2 h from the low bile cultures.
2010-06-05 | E-GEOD-6468 | biostudies-arrayexpress
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2010-06-09 | E-GEOD-1038 | biostudies-arrayexpress
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2010-06-09 | E-GEOD-1044 | biostudies-arrayexpress
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Project description:The kep1 gene encodes an RNA-binding protein containing a single maxi-KH domain. We have previously demonstrated that loss of the kep1 gene results in Drosophila females displaying a reduction in fertility and wished to further characterize the kep1 mutation in Drosophila males. Wild-type females mated to homozygous kep1- males resulted in 6% of the eggs laid hatching. This reduced reproductive success is due in part to a meiosis defect during spermatogenesis with approximately 10 % of sperm demonstrating a defect in cytokinesis. Utilizing indirect immunohistochemistry we found that the Kep1 protein is present in the nucleus of adult brain neuronal cells, suggesting a behavioural component contributing to the almost complete male sterility phenotype. We report that homozygote kep1- males display almost no courtship behaviour with a measured median courtship index of 0.005 relative to a median index of 0.77 for OreR wild-type controls. In order to better understand the behavioural role of kep1, we carried out gene profiling experiments to identify transcripts whose steady-state levels are altered in the kep1- homozygote males. Our gene profiling studies identified 61 transcripts whose steady-state levels are altered by at least 2 fold or more comparing RNA isolated from w1118 and kep1-/kep1- male heads. A large percentage of transcripts identified whose steady-state expression levels are depleted in kep1-/kep1- heads (10 out of 44) encode for proteins involved in some aspect of proteolysis. Our results show that the Kep1 protein has a pleiotropic effect in Drosophila males leading to cytokinesis defects and behavioural abnormalities. RNA was isolated from heads of 3-4 day old wild-type or homozygote mutant males. Three indepentent RNA samples were utilized to complete experiment.
2010-06-10 | E-GEOD-6086 | biostudies-arrayexpress
Project description:We measured gene expression in two isogenic Drosophila lines heterozygous for long deletions. We find that a majority of genes are at least partially compensated at transcription for ½-fold dosage. The degree of compensation does not vary among functional classes of genes. Compensation for deletions is stronger for highly expressed genes than for genes with low expression level. In contrast, the degree of compensation for duplications observed in Gupta et al, 2006, (J. of Biology 5, 3) data for heterozygotes for a duplication is stronger for weakly expressed genes. Thus, transcriptional compensation appears to be based on general regulatory mechanisms that insure high levels of transcription some genes and low transcription levels of other genes, instead of precise maintenance of a particular homeostatic expression level. Given the ubiquity of transcriptional compensation, dominance of wild-type alleles may be at least partially caused by of the regulation at transcription level. Keywords: Genome-wise dosage compensation study Two DrosDel [34] Drosophila melanogaster isogenic lines, Df(3L)ED4475 and Df(3L)ED4543, heterozygous for long deletions on 3L chromosomal branch both maintained against the TM6C balancer were used for microarray experiment. Twenty five adult flies 2-5 days after eclosion were frozen in liquid nitrogen and used for RNA extraction by Trizol method (Invitrogen ®, Carlsbad, CA) in twelve replicates from each line. The two deletion lines served as controls to each other.
2010-06-20 | E-GEOD-14799 | biostudies-arrayexpress
Project description:Oxygen lack of various severity can force many organisms to enter into recoverable hypometabolic states. To better understand how organisms cope with oxygen deprivation, our lab had previously shown that when challenged with anoxia, both the nematode Caenorhabditis elegans and embryos of the zebrafish Danio rerio enter into suspended animation, where all life processes that can be observed by light microscopy reversibly halt, pending restoration of oxygen. Here, we show that both sporulating and vegetative cells of the budding yeast Saccharomyces cerevisiae also enter into a similar state of suspended animation when made anoxic on a non-fermentable carbon source. Transcriptional profiling using cDNA microarrays shows upregulation of aerobic metabolism genes in carbon monoxide (CO)-induced anoxia, but not nitrogen (N2) gas-induced anoxia, consistent with the known oxygen-mimetic effects of CO. Our results lead us to propose a model for oxygen-regulated gene expression in yeast where two oxygen-sensitive mechanisms operate simultaneously, such that treatment with N2 results in both mechanisms signaling a lack of oxygen, while treatment with CO results in one sensing mechanism signaling a lack of oxygen, while the other signals an abundance of oxygen. Cells were pregrown on glucose media. Cells were then plated onto nylon membranes on acetate solid media and made anoxic using either pure nitrogen or carbon monoxide. Cells were collected at 15, 30, 45, 60, 120 minutes and 24 hours after initiation of gas exposure. Reference samples were derived from cells on acetate in room air for corresponding time point. Six CO-treated samples were compared to room air references and six nitrogen-treated samples were similarly compared to room air references.
2008-07-08 | E-GEOD-12004 | biostudies-arrayexpress
Project description:Biallelic inactivating mutations of the transcription factor 1 gene (TCF1), encoding hepatocyte nuclear factor 1a (HNF1a), were identified in 50% of hepatocellular adenomas (HCA) phenotypically characterized by a striking steatosis. To understand the molecular basis of this aberrant lipid storage, we performed a microarray transcriptome analysis validated by quantitative RT-PCR, western-blotting and lipid profiling. In mutated HCA, we showed a repression of gluconeogenesis coordinated with an activation of glycolysis, citrate shuttle and fatty acid synthesis predicting elevated rates of lipogenesis. Moreover, the strong dowregulation of L-FABP suggests that impaired fatty acid trafficking may also contribute to the fatty phenotype. In addition, transcriptional profile analysis of the observed deregulated genes in non-HNF1a-mutated HCA as well as in non-tumor livers allowed us to define a specific signature of the HNF1a-mutated HCA. In theses tumors, lipid composition was dramatically modified according to the transcriptional deregulations identified in the fatty acid synthetic pathway. Surprisingly, lipogenesis activation did not operate through SREBP-1 and ChREBP that were repressed. We conclude that steatosis in HNF1a-mutated HCA results mainly from an aberrant promotion of lipogenesis that is linked to HNF1a inactivation and that is independent of both SREBP-1 and ChREBP activation. Finally, our findings have potential clinical implications since lipogenesis can be efficiently inhibited by targeted therapies. Keywords: Disease state analysis In a first experiment, microarray analyses were applied to 8 HNF1-alpha mutated HCA and their corresponding non-tumor livers using cDNA in-house manufactured arrays following a randomized and blinded unbalanced design. RNA labelling, hybridization and analysis of fluorescence was carried out, as described in [Graudens et al., Genome Biol 2006, 7: R19; PMID: 16542501], considering that uneven numbers of samples were randomly allocated to each of the engineers who were not aware of sample phenotypes. To assess data reproducibility and minimize dye bias effects, each of the samples was measured four times, twice with Cy3 and twice with Cy5. To ensure robustness and flexibility in data analysis, a reference design was used with a universal reference sample (Stratagene, USA) serving as a baseline for the comparisons of tumor samples. Hybridizations were performed onto an 11K human array (11K_VJF-ARRAY, GPL3282), which provides a genome-wide coverage of functional pathways. Raw data were obtained using the ArrayVisionM-bM-^DM-" 7.0 software (Imaging Research Inc., USA); the resulting 3.2x106 hybridization data points collected from 32 arrays were stored in a MIAME-compliant database and pre-processed for normalization and filtering as described in [Graudens et al., Genome Biol 2006, 7: R19; PMID: 16542501]. In a second experiment, HG-U133A Affymetrix GeneChipTM arrays were used to compare the expression profiles of 5 HNF1-alpha mutated HCA and 4 non related non-tumor livers. RNA labelling, hybridization and analysis were carried out following the manufacturerM-bM-^@M-^Ys instructions(Affymetrix, Santa Clara, CA). Raw data were obtained by using Microarray Suite 5.0 (MAS5) software, embedded in the Affymetrix GeneChip Operating Software (Santa Clara, USA); the resulting raw numerical data (CEL files) - available as supplementary files - collected from 9 Affymetrix GeneChips were pre-processed for normalization and filtering as described in [Rebouissou et al., J Biol Chem 2007, in press; PMID: 17379603]. A platform-dependant statistical comparison was performed considering HNF1 alpha-mutated HCA versus non tumor liver tissues, using multiple testing procedures to evaluate statistical significance for differentially expressed genes, as described in [Graudens et al., Genome Biol 2006, 7: R19; PMID: 16542501] and in the supplemental experimental procedures in [Rebouissou et al., J Biol Chem 2007, in press; PMID: 17379603]. Thus, a combined cross-platform analysis was done considering the UGCluster Identifiants as a common primary key (Unigene Build184-June05). Additional information on the procedures is provided in the supplemental experimental procedures in [Rebouissou et al., J Biol Chem 2007, in press; PMID: 17379603].
2007-05-01 | E-GEOD-7473 | biostudies-arrayexpress
Project description:Cold hardening treatment, a brief exposure to low temperatures (e.g. 0°C for 2 h), can protect certain insects against subsequent exposure to temperatures sufficiently low to cause damage or lethality. Microarray analysis to examine the changes in transcript abundance associated with cold hardening has been undertaken in Drosophila melanogaster in order to gain insight into this phenomenon. Transcripts associated with 36 genes were identified, a subset of which appeared to be also differentially expressed after heat shock treatment. Quantitative RT-PCR was used to independently determine transcript abundance of a subset of these sequences. Taken together, these assays suggest that stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response. Co-reared flies were separated into a control group and a treatment group at random. RNA was isolated from the cold-shocked flies and the respective controls and was used for direct comparisons on cDNA microarrays. Treatments were not varied as they had been optimized in previous studies. A pilot experiment was performed using the Drosophila 7k2 array (GPL311) and subsequently three pairs of independent biological samples were evaluated with the Drosophila 12k1 array (GPL1467).
2005-11-30 | E-GEOD-2989 | biostudies-arrayexpress