Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

The contributions of sex, genotype and age to transcriptional variance in Drosophila melanogaster

ABSTRACT: Here we present a statistically rigorous approach to quantifying microarray expression data that allows the relative effects of multiple classes of treatment to be compared and incorporates analytical methods that are common to quantitative genetics. From the magnitude of gene effects and contributions of variance components, we find that gene expression in adult flies is affected most strongly by sex, less so by genotype and only weakly by age (for 1- and 6-wk flies); in addition, sex-genotype interactions may be present for as much as 10% of the Drosophila transcriptome. This interpretation is compromised to some extent by statistical issues relating to power and experimental design. Nevertheless, we show that changes in expression as small as 1.2 fold can be highly significant. Genotypic contributions to transcriptional variance may be of a similar magnitude to those relating to some quantitative phenotypes and should be considered when assessing the significance of experimental treatments. The experimental design consisted of 24 cDNA microarrays, 6 for each combination of 2 genotypes (Oregon R and Samarkand) and the 2 sexes, involving 48 separate labeling reactions. We directly contrasted two time points, 1-wk and 6-wk adult flies, on each microarray. The dyes Cy3 and Cy5 were flipped for two of the six replicates of each genotype and sex combination. A common reference sample was not used. In total, we spotted 4,256 clones, representing a third of the genome, two-thirds of which were verified by resequencing before printing. We excluded 325 clones from the analysis because no consistent expression above background was detected.

ORGANISM(S): Drosophila melanogaster

SUBMITTER: Stan Martin

PROVIDER: E-GEOD-13928 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The contributions of sex, genotype and age to transcriptional variance in Drosophila melanogaster.

Jin W W Riley R M RM Wolfinger R D RD White K P KP Passador-Gurgel G G Gibson G G

Nature genetics 20011201 4

Here we present a statistically rigorous approach to quantifying microarray expression data that allows the relative effects of multiple classes of treatment to be compared and incorporates analytical methods that are common to quantitative genetics. From the magnitude of gene effects and contributions of variance components, we find that gene expression in adult flies is affected most strongly by sex, less so by genotype and only weakly by age (for 1- and 6-wk flies); in addition, sex x genotyp ...[more]

PMID: 11726925

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Project description:Tsetse flies (Glossina spp.) are major vectors of African trypanosomes, causing either Human or Animal African Trypanosomiasis (HAT or AAT). Several approaches are developed to control the disease among which the anti-vector Sterile Insect Technique. Another approach in the frame of anti-vector strategies could consist in controlling the fly’s vector competence which needs identifying factors (genes, proteins, biological pathways, …) involved in this process. The present work aims to verify whether protein candidates identified under experimental controlled conditions on insectary-reared tsetse flies have their counterpart in field-collected flies. Glossina palpalis palpalis flies naturally infected with Trypanosoma congolense were sampled in two HAT/AAT foci in Southern Cameroon. After dissection, the proteome from guts of parasite-infected flies were compared to that from uninfected flies in order to identify quantitative and/or qualitative changes associated to infection. A total of 3291 proteins were identified of which 1818 could be quantified. The comparative analysis allowed identifying 175 proteins with significant decreased abundance in infected as compared to uninfected flies, while 61 proteins displayed increased abundance. Among the former are RNA binding proteins, kinases, actin, ribosomal proteins, endocytosis proteins, oxido-reductases, as well as proteins that are unusually found such as tsetse salivary proteins (Tsal) or Yolk proteins. Among the proteins with increased abundance are fructose-1,6-biphosphatase, serine proteases, membrane trafficking proteins, death proteins (or apoptosis proteins), and SERPINs (inhibitor of serine proteases, enzymes considered as trypanosome virulence factors) that displayed highest increased abundance. Sodalis, Wiggleswothia and Wolbachia proteins are strongly under-represented, particularly when compared to data from similar experimentation conducted under controlled conditions on T. brucei gambiense infected (or uninfected) G. palpalis gambiensis insectary reared flies. Comparing the overall recorded data, 364 proteins identified in gut extracts from field flies were shown to have a homologue in insectary flies. Discrepancies between the two studies may arise from differences in the species of studied flies and trypanosomes as well as in differences in environmental conditions in which the two experiments were carried out. Finally, the present study together with former proteomic and transcriptomic studies on the secretome of trypanosomes, on the gut extracts from insectary reared and on field collected tsetse flies, provide a pool of data and information on which to draw in order to perform further investigations on, for example, mammal host immunization or on fly vector competence modification via para-transgenic approaches.

Project description:Transcript abundance was measured in whole-body virgin male Drosophila serrata from 41 inbred lines that had diverged through 27 generations of mutation accumulation that were sexually selected Sexual selection is predicted to have widespread effects on the genetic variation generated by new mutations as a consequence of the genic capture of condition by male sexual traits. We manipulated the opportunity for sexual selection on males during 27 generations of mutation accumulation in inbred lines of Drosophila serrata, and used a microarray platform to investigate the effect of sexual selection on the expression of 2685 genes, representing a broad coverage of biological function. Sexual selection had little effect on mean gene expression levels, with only 4 genes diverging significantly at a false discovery rate of 5% . In contrast, sexual selection impacted on both the magnitude and nature of mutational variance accumulating in these genes. The magnitude of mutational variance increased under sexual selection by an average of 29%. Mutational variance was less commonly generated by extreme phenotypes less commonly under sexual selection. Furthermore, analysis of random sets of five genes revealed that the mutational variance that accumulated under sexual selection was less pleiotropic in nature than that found in the absence of sexual selection. The generation of greater mutational variance without a general concomitant change in mean expression under sexual selection suggested that gene expression traits were be under apparent rather than direct sexual selection. We discuss two main explanations for the broad-based increase in mutational variance under sexual selection that both require extensive pleiotropy between traits affecting male mating success, standard metric traits represented here by gene expression traits, and general fitness. We measured gene expression of male Drosophila serrata from 41 mutation accumulation lines (whole-body) that were sexually selected. Data from two replicates for each line are presented.

Dataset Information

The contributions of sex, genotype and age to transcriptional variance in Drosophila melanogaster

Publications

The contributions of sex, genotype and age to transcriptional variance in Drosophila melanogaster.

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