The effect of sex on gene expression variation within and between populations of Drosophila melanogaster
ABSTRACT: To investigate the effect of sex on within- and between-population variation in gene expression, we performed a microarray analysis of adult females from 16 strains of Drosophila melanogaster, including eight strains from the putative ancestral range in sub-Saharan Africa and eight strains from a European population. The results were compared to those of a previous study of adult male gene expression variation among the same strains (GSE8843). We used dual-channel microarrays to compare genome-wide expression profiles in adult females from 16 inbred strains derived from two natural populations. In total, 56 hybridizations were performed including dye-swaps. The hybridization scheme consisted of a balanced loop design, which allowed an unbiased comparison of relative expression levels within and between populations.
Project description:Background: Differences in levels of gene expression among individuals are an important source of phenotypic variation within populations. Recent microarray studies have revealed that expression variation is abundant in many species, including Drosophila melanogaster. However, previous expression surveys in this species generally focused on a small number of laboratory strains established from derived populations. Thus, these studies were not ideal for population genetic analyses. Results: We surveyed gene expression variation in adult males of 16 D. melanogaster strains from two natural populations, including an ancestral African population and a derived European population. Levels of expression polymorphism were nearly equal in the two populations, but a higher number of differences was detected when comparing strains between populations. Expression variation was greatest for genes associated with few molecular functions or biological processes, as well as those expressed predominantly in males. Our analysis also identified genes that differed in expression level between the European and African populations, which may be candidates for adaptive regulatory evolution. Genes involved in flight musculature and fatty acid metabolism were over-represented in the list of candidates. Conclusions: Overall, stabilizing selection appears to be the major force governing gene expression variation within populations. However, positive selection may be responsible for much of the between-population expression divergence. The nature of the genes identified to differ in expression between populations may reveal which traits were important for local adaptation to the European and African environments. We used dual channel microarrays to compare genome-wide expression profiles in adult males from 16 inbred strains derived from two natural populations. In total 80 hybidizations were performed including dye-swaps. The hybridization scheme consisted of a balanced loop design, which allowed an unbiased comparison of relative expression levels within and between populations.
Project description:Over-expression of wild type PrP in skeletal muscles is sufficient to cause a primary myopathy with no signs of peripheral neuropathy, possibly due to accumulation of a cytotoxic truncated form of PrP and/or PrP aggregation. In this study we used DNA microarrays to identify 1499 transcripts that are temporally deregulated concomitant with inducible PrPC over-expression in the skeletal muscles of transgenic mice. Examination using microarrays revealed a transcriptional profile with both similarities and differences to previously investigated models of myopathies. Down-regulation of genes coding for the myofibrillar proteins MYH2, MYH6, MYH7, MYL2, MYL3 and up-regulation of lysosomal genes CTSS, CTSD, CTSZ, DPEP2, HEXA, HEXB and LAMP1 coincide with the observed myopathy and lysosome accumulation on over-expression of PrPC. Down-regulation of the MEF2C gene, a key regulatory transcriptional factor muscle development and remodeling of adult muscles in response to physiologic and pathologic signals, may contribute to the centrally placed nuclei in the skeletal muscles. Significantly, up-regulation of genes involved in p53 signaling and the induction of p53 protein, suggest a central role for this molecule in the myopathy. Several p53-regulated genes involved in cell cycle arrest (CDNK1A, GADD45a and GADD45b) and apoptosis (BAK1, PMAIP1, BBC3, and BAX) are induced. We suggest that PrPC over-expression in skeletal muscles, possibly in response to accumulation of a cytotoxic truncated form of PrP, causes a primary myopathy involving the induction of p53-dependent pathways. Wild type (WT), PrP-null (KO), and Tg(HQK) mice were fed food pellets either lacking or containing 6g doxycycline (Dox)/kg food to induce PrPC expression. Skeletal muscles from the quadriceps of hind legs were removed at day 0, 4, 7, 14, 30 and 60 days following administration of Dox. Total RNA was isolated from these tissues for use in subsequent microarray analysis. Mouse gene expression was analysed by two-colour microarray experiments using an inhouse manufactured 16K mouse cDNA microarray. Age matched reference mice (WT) and experimental (KO and HQK) Alexa Flour labeled aRNA were used in each competitive hybridization. Each sample was labeled individually with both Alexa Fluor 555 and 647 for subsequent dye-swapped hybridizations to account for intensity bias. 3 individual mice from each experimental group at each time point were individually processed for separate microarrays. We used the program EDGE to identify genes that were differentially expressed in mouse skeletal muscle in either transgenic HQK mice over expressing PrP, or PrP knock out (KO) mice after administration of Dox. We used a P value cut-off of 0.05 as the criteria of selection of significantly differentially expressed genes.
Project description:A total of 192 genes were found to be differentially expressed; 38 genes of them were up regulated and 154 genes were down regulated. Most notably the functional categories that were affected include carbohydrate metabolism and cell envelop realted genes ( 56, 29.1% of the total),Virulence genes (12 genes 6.25% of the total significantly differentiated genes), and aminoacid transport genes (7 genes, 3.6 %). Among the virulence-related genes, the most notable ones were those belong to the production of capsule, the M protein, exotoxin, NAD glycohydrolase and Streptolysin S. Some of the capsule related genes were down regulated by more than 64 fold. Additionally 11 differentially expressed lipid metabolism related genes and four aminoacid transport and metabolism-related genes were upregulated. These results indicate that the C-terminal CHAP domain of CdhA (group A Streptococcal Cell division controlling and Chain-forming cell wall hydrolase) plays an important role in the regulation of virulence. Since these mutant lack cell wall hydrolase activity but are not defective in cell division or growth, we believe that CdhA isa multifunctional protein with N-terminal region controlling cell division and c-terminal region responsible for regulating bacterial virulence. S. pyogenes strain SF370 (wild-type) was procured from ATCC (ATCC 700294). M1-CdhA55(-) mutant strain was obtained using pFW5 vector containing spectinomycin resistance marker (aad9). The mutant expressing truncated CdhA that lack C-terminal 55 residues constituting catalytic site of the CHAP domain is not defective in cell division and growth, but lacks antiphagocytic property and attenuated for virulence. Both strains (M1-Wild-type and M1-CdhA55(-) were grown in Todd-Hewitt broth to their late log phase. Bacteria were harvested by centrifugation and washed twice with sterile PBS. Total RNA was isolated from these washed streptococci using Qiagen RNeasy Mini kit. For synthesis and labeling of cDNA, 20 ug of total RNA, 1.5 ug of random hexamer, 0.5mM dNTPs (except that 0.2mM of dTTP was replaced by the same amount of amino-allyl dUTP to incorporate dUTP into first-strand cDNA) were used in each reverse transcriptase reaction (Superscript II Reverse Transcriptase, Invitrogen). Purified cDNA preparations from the wild-type and M1-CdhA55(-) mutant strains were labeled with either Alexafluor-555 or Alexafluor-647 depending on the experimental design ( i.e. dye swap experiment). Differentially labeled probes were then combined and purified. Using three independently isolated RNA preparations (biological replicates), a total of 7 experiments (incorporating dye swaps) were performed. Accordingly 7 hybridization measurements for this mutant were performed. Thus Exp-1 and 2 (GSM389993, GSM389994) are the technical replicates of the biological sample-1, Exp-3 and 4 (GSM389995, GSM390054) are technical replicates of biological sample-2 and Exp-5,-6, and -7 (GSM390055,GSM390056, and GSM390057) are technical replicates of the biological sample-3. Signals of the bound reagents on the microarray spots in terms of relative fluorescence values were measured and quantified by a laser scanner (GenePix 4100 ) at 10um/pixel resolution. The resulting images were processed using Gene Pix Pro software (version 4.0, Axon instruments). The raw data were obtained in the form of GenPix *.gpr output files. The web application CARMAweb (Comprehensive R based microarray analysis web service) was used for the normalization and analysis of microarray data. All raw data (in the form of *. GPR files) were uploaded to the web application in the data directory. Using appropriate navigation tree, background correction from the foreground signal was applied and within microarray normalization was achieved using the Lowess method. Genes flagged as bad spots by the scanning software were excluded from the analysis and all flagged spots were given a weight of zero. The normalized data were then subjected to fold-change analysis and t-statistics using Bioconductor multtest package. CARMAweb allows to set Log2 cut-off values for both the M (regulation) and the A (average expression) values. Differentially expressed genes (Log2 values of Mutant647-red vs. wild-type555-green or Log2 values Mutant-555(green) vs Wild-type 647-red) were defined based on cut-off value >1 Log2< i.e. all genes that show a two or more-fold up- or down-regulation. BioConductors Multtest package provided suitable method to adjust P values according to multiple hypothesis testing problems.
Project description:Transcriptional and translational profiling of RPL12A/B double deletion comparing control untransformed RPL12B strains with transformed with a pESC-RPL12B wild type or muated RPL12B-R66K gene. Keywords: Genetic modification Two-condition experiment, Transcriptional experiments from total mRNA and Translational experiments from polysomal mRNA from three strains including deleted RPL12A/B, retransformed WT RPL12B and mutated RPL12B-R66K strain. Biological replicates: independently grown and harvested. double, triple or more replication per array.
Project description:Chickens divergently selected for either high abdominal fat content (fat genotype) or low abdominal fat content (lean genotype) at SRA-INRA, France were used to profile hepatic gene expression during juvenile development (1 to 11 weeks of age) and to identify differentially expressed genes associated with genotype and age. The fat line (FL) and lean line (LL) chickens are different in various phenotypic and metabolic measurements, including abdominal fatness, plasma glycemia and T3. The FL and LL chickens represent unique models for characterizing biomedical and agricultural traits. The Del-Mar 14K Chicken Integrated Systems microarrays were used for a transcriptional scan in liver during juvenile development using a balanced block hybridization design. Log2-transformed fluorescence intensities were analyzed with a two-stage mixed model. A total of 905 differentially expressed "functional" genes were identified (FDR<0.10). The greatest number of differentially expressed genes (400) was detected at 7 weeks of age. The differentially expressed genes include metabolic enzymes, acute phase proteins, growth factors, immune factors and transcription factors involved in various pathways. Several of the functional genes are also identified as positional candidate genes within QTLs in an F2 population established from an intercross between the FL and LL lines. A balance block design was used for microarray hybridizations, where half of the birds of each genotype and age were labeled with Alexa Flour 647 (red) and the other half with Alexa Flour 555 (green). Four biological replicates were used for each genotype (FL or LL) at six different ages (1, 3, 5, 7, 9 and 11 wk).
Project description:Abstract of associated manuscript: The Bacillus subtilis extracytoplasmic function (ECF) sigma(M) factor is activated by cell envelope stress elicited by antibiotics, and by acid, heat, ethanol and superoxide stresses. Here, we have used several complementary approaches to identify genes controlled by sigma(M). In many cases, expression is only partially dependent on sigma(M) because of both overlapping promoter recognition with other ECF sigma factors and the presence of additional promoter elements. Genes regulated by sigma(M) have a characteristic pattern of induction in response to cell envelope-acting antibiotics as evidenced by hierarchical clustering analysis. sigma(M) also contributes to the expression of the Spx transcription factor and thereby indirectly regulates genes of the Spx regulon. Cell envelope stress responses also include regulons controlled by sigma(W), sigma(B) and several two-component regulatory systems (e.g. LiaRS, YycFG, BceRS). Activation of the sigma(M) regulon increases expression of proteins functioning in transcriptional control, cell wall synthesis and shape determination, cell division, DNA damage monitoring, recombinational repair and detoxification. WT (-van) vs. WT (+van), sigM (-van) vs. sigM (+van), WT (-van) vs. sigM (-van), WT (+van) vs. sigM (+van), WT (-van) vs. spx (-van), WT (+van) vs. spx (+van). Each experiment was conducted at least twice using two independent total RNA preparations. For vancomycin untreated and treated experiments, untreated samples were labeled with Alexa Fluor 555 and treated samples with Alexa Fluor 647. For WT vs. mutant experiments, wild type was labeled with Alexa Fluor 555 and mutants with Alexa Fluor 647. For dye swap experiment, wild-type was labeled with Alexa Fluor 647 and mutant with Alexa Fluor 555. Bacillus subtilis CU1065, WT (-van) vs. WT (+van), sigM (-van) vs. sigM (+van), WT (-van) vs. sigM (-van), WT (+van) vs. sigM (+van), WT (-van) vs. spx (-van), WT (+van) vs. spx (+van)
Project description:The aim of this study was to identify quantitative trait loci (QTL) associated with variation in circadian photosensitivity in Drosophila, by measuring the locomotor response to early night light pulse (Zt15). We used QTL mapping of recombinant inbred lines (RIL), which was followed by microarrays expression comparison of two RI lines which differed significantly in their light response (RIL 104 shows a strong long phase delay response while RIL 58 shows a weak light response). Each of the two strains was sampled after light pulse, and without a light pulse (control), totalling 8 samples: 2x lines (L) x treatments (T) x 2 replicates
Project description:Saccharomyces spp. are widely used for ethanol production however fermentation productivity is negatively affected by the impact of ethanol accumulation on yeast metabolic rate and viability. This study used microarray and statistical two-way ANOVA analysis to compare and evaluate gene expression profiles of two previously generated ethanol-tolerant mutants, CM1 and SM1, with their parent, S. cerevisiae W303-1A, in the presence and absence of ethanol stress. Although sharing the same parentage, the mutants were created differently; SM1 by adaptive evolution involving long-term exposure to ethanol stress, and CM1 using chemical mutagenesis followed by adaptive evolution-based screening. Compared to the parent, differences in the expression levels of genes associated with a number of GO categories in the mutants suggest that their improved ethanol stress response is a consequence of increased mitochondrial and NADH oxidation activities, stimulating glycolysis and energy production. This leads to increased activity of energy-demanding processes associated with the production of proteins and plasma membrane components, which are necessary for acclimation to ethanol stress. It is suggested that a key function of the ethanol stress response is restoration of the NAD+/NADH redox balance, which increases glyceraldehyde-3-phosphate dehydrogenase activity, and higher glycolytic flux in the ethanol-stressed cell. Both mutants achieved this by a constitutive increase in carbon flux in the glycerol pathway as a means of increasing NADH oxidation. Two conditions: 0% and 6.5 % (v/v) ethanol added to the culture growth medium for each strain. One set of triplicates with one dye swap for each condition. Each triplicate was prepared from different biological replicate (i.e. different culture).
Project description:To understand the extent that Heat shock protein 90 (Hsp90) regulated its target proteins at the transcription level, transcriptomic change was profiled in yeast cells upon Hsp90 compromising. We genetically modified the R1158 strain (resulting genotype of mutant strain: TETp-HSC82 hsp82Δ arg4Δ lys5Δ car2Δ::URA3) and then reduced the Hsp90 amount with doxycycline treatment. Fold change of mRNA from untreated to treated cells indicated the transcriptomic change. Totally, we identified 1104 genes mis-regulated with a fold change of no less than 1.5 (P <0.05) upon Hsp90 compromising. Two-condition experiment, treated vs. untreated cells. Biological duplicates, independently grown and harvested. Technical triplicates for RNA isolation.