Project description:eQTL mapping in a F1 diversity panel generated from 111 A.thaliana natural accessions 57 F1 lines without replicates, the 5th or 6th true leaf
Project description:Mapping of expression quantitative trait loci (eQTL) is a powerful means for elucidating the genetic architecture of gene regulation. Yet, eQTL mapping has not been applied towards investigating the regulation architecture of genes involved in the process of population divergence, ultimately leading to speciation events. Here, we conducted an eQTL mapping experiment to compare the genetic architecture of transcript regulation in adaptive traits differentiating the recently evolved limnetic (dwarf) and benthic (normal) species pairs of lake whitefish. The eQTL were mapped in three data sets derived from a F1 hybrid-dwarf backcrossed family: the entire set of 66 genotyped individuals, and the two sexes treated separately. We identified strikingly more eQTL in the female dataset (174), compared to both male (54) and combined (33) data sets. The majority of these genes were not differentially expressed between male and female progeny of the backcross family, thus providing evidence for a strong pleiotropic sex-linked effect in transcriptomic regulation. The subtelomeric region of a linkage group segregating in females encompassed more than 50% of all eQTL, which exhibited the most pronounced additive effects. We also conducted a direct comparison of transcriptomic profiles between pure dwarf and normal progeny reared in controlled conditions. We detected 34 differentially expressed transcripts associated with eQTL segregating only in sex-specific data-sets, and mostly belonging to functional groups that differentiate dwarf and normal whitefish in natural populations. Therefore, these eQTL are not related to inter-individual variation, but instead to the adaptive and historical genetic divergence between dwarf and normal whitefish. This study exemplifies how the integration of genetic and transcriptomic data offers a strong means for dissecting the functional genomic response to selection by separating mapping family specific effects from genetic factors under selection, potentially involved in the phenotypic divergence of natural populations. Keywords: eQTL mapping
Project description:In this study we use RNAseq to explore allele specific expression (ASE) in adipose tissue of male and female F1 mice, produced from reciprocal crosses of C57BL/6J and DBA/2J strains. Comparison of the identified cis-eQTLs, to local-eQTLs, that were obtained from adipose tissue expression in two previous population based studies in our laboratory, yields poor overlap between the two mapping approaches, while both local-eQTL studies show highly concordant results. Specifically, local-eQTL studies show ~60% overlap between themselves, while only 15-20% of local-eQTLs are identified as cis by ASE, and less than 50% of ASE genes are recovered in local-eQTL studies. Utilizing recently published ENCODE data, we also find that ASE genes show significant bias for SNPs prevalence in DNase I hypersensitive sites that is ASE direction specific. We suggest a new approach to analysis of allele specific expression that is more sensitive and accurate than the commonly used fisher or chi-square statistics. Our analysis indicates that technical differences between the cis and local-eQTL approaches, such as differences in genomic background or sex specificity, account for relatively small fraction of the discrepancy. Therefore, we suggest that the differences between two eQTL mapping approaches may facilitate sorting of SNP-eQTL interactions into true cis and trans, and that a considerable portion of local-eQTL may actually represent trans interactions.
Project description:In this study we use RNAseq to explore allele specific expression (ASE) in adipose tissue of male and female F1 mice, produced from reciprocal crosses of C57BL/6J and DBA/2J strains. Comparison of the identified cis-eQTLs, to local-eQTLs, that were obtained from adipose tissue expression in two previous population based studies in our laboratory, yields poor overlap between the two mapping approaches, while both local-eQTL studies show highly concordant results. Specifically, local-eQTL studies show ~60% overlap between themselves, while only 15-20% of local-eQTLs are identified as cis by ASE, and less than 50% of ASE genes are recovered in local-eQTL studies. Utilizing recently published ENCODE data, we also find that ASE genes show significant bias for SNPs prevalence in DNase I hypersensitive sites that is ASE direction specific. We suggest a new approach to analysis of allele specific expression that is more sensitive and accurate than the commonly used fisher or chi-square statistics. Our analysis indicates that technical differences between the cis and local-eQTL approaches, such as differences in genomic background or sex specificity, account for relatively small fraction of the discrepancy. Therefore, we suggest that the differences between two eQTL mapping approaches may facilitate sorting of SNP-eQTL interactions into true cis and trans, and that a considerable portion of local-eQTL may actually represent trans interactions. 4 samples - male and female, BxD and DxB adipose of pooled RNA (3 animals per pool) were analyzed with high coverage RNAseq data.
Project description:Mapping of expression quantitative trait loci (eQTL) is a powerful means for elucidating the genetic architecture of gene regulation. Yet, eQTL mapping has not been applied towards investigating the regulation architecture of genes involved in the process of population divergence, ultimately leading to speciation events. Here, we conducted an eQTL mapping experiment to compare the genetic architecture of transcript regulation in adaptive traits differentiating the recently evolved limnetic (dwarf) and benthic (normal) species pairs of lake whitefish. The eQTL were mapped in three data sets derived from a F1 hybrid-dwarf backcrossed family: the entire set of 66 genotyped individuals, and the two sexes treated separately. We identified strikingly more eQTL in the female dataset (174), compared to both male (54) and combined (33) data sets. The majority of these genes were not differentially expressed between male and female progeny of the backcross family, thus providing evidence for a strong pleiotropic sex-linked effect in transcriptomic regulation. The subtelomeric region of a linkage group segregating in females encompassed more than 50% of all eQTL, which exhibited the most pronounced additive effects. We also conducted a direct comparison of transcriptomic profiles between pure dwarf and normal progeny reared in controlled conditions. We detected 34 differentially expressed transcripts associated with eQTL segregating only in sex-specific data-sets, and mostly belonging to functional groups that differentiate dwarf and normal whitefish in natural populations. Therefore, these eQTL are not related to inter-individual variation, but instead to the adaptive and historical genetic divergence between dwarf and normal whitefish. This study exemplifies how the integration of genetic and transcriptomic data offers a strong means for dissecting the functional genomic response to selection by separating mapping family specific effects from genetic factors under selection, potentially involved in the phenotypic divergence of natural populations. Keywords: eQTL mapping Dissected white muscle tissue (250-350 mg) was sampled for 76 individuals from the hybrid x dwarf backcross mapping family. We used a loop design (YANG and SPEED 2002; CHURCHILL 2002) to maximize the number of sampled meioses. Each of 76 samples was technically replicated on two distinct slides, while performing dye swapping (Cy3 and Alexa) to estimate the dye intensity variation bias. After correcting for local background, raw intensity values were both log2 transformed and normalized using the regional LOWESS method implemented in the R/MANOVA software (KERR et al. 2000). The design file used for the maanova analysis is linked below as a supplementary file.
Project description:A QTL analysis between inbred mouse strains MRL/MpJ and SM/J was performed to identify genetic loci influencing high-density lipoprotein (HDL) cholesterol and triglycerides (TG) at eight weeks of age in F2 mice fed a chow diet. In order to narrow down lists of candidate genes, expression levels from liver tissue were used to test for differential expression among parental and F1 strains and to scan for eQTL in F2 animals. We provide evidence for Mppe1 (Chr 18) as an HDL QTL candidate gene and Cyp2d26 (Chr 15) as a TG QTL candidate gene. MRL/MpJ (MRL) mice were crossed with male SM/J (SM) mice; their progeny were intercrossed to produce 371 F2 animals. Of these, 282 F2 males and females were profiled with Affy Mouse Gene 1.0 ST arrays for an eQTL study. Three animals from each parental and the F1 strains from each sex, i.e. 18 in total, were also profiled for testing differential expression. A total of 300 samples are included in the dataset. The mice were weaned at 3 weeks on a chow diet. At 13 weeks of age, mice were single housed for 3 days and fasted for 4 hours prior to being sacrificed. Tissue collection was performed between noon and 1pm to avoid variations due to circadian rhythm.
Project description:Recent genome-wide association studies have identified single nucleotide polymorphisms (SNPs) at 7 loci influencing multiple myeloma (MM) risk. We generated expression quantitative trait loci (eQTL) data on malignant plasma cells from two patient series (totaling 848) to fine map the risk loci associations and gain insight into their functional basis. At 7p11.2 the strongest association with MM risk is provided by rs4487645, which is associated with allele–specific cis-regulation of the MYC-interacting gene CDCA7L (P=4.1x10-25). These data are compatible with increased expression of CDCA7L being the functional basis of the 7p11.2 association exerting its effects through an extended pathway involving IRF4 and MYC. Note: This dataset re-uses files from ArrayExpress accessions E-TABM-937, E-MTAB-362, E-MTAB-372.
Project description:A QTL analysis between inbred mouse strains MRL/MpJ and SM/J was performed to identify genetic loci influencing high-density lipoprotein (HDL) cholesterol and triglycerides (TG) at eight weeks of age in F2 mice fed a chow diet. In order to narrow down lists of candidate genes, expression levels from liver tissue were used to test for differential expression among parental and F1 strains and to scan for eQTL in F2 animals. We provide evidence for Mppe1 (Chr 18) as an HDL QTL candidate gene and Cyp2d26 (Chr 15) as a TG QTL candidate gene.