Project description:We analyzed allele-specific expression (ASE) in leaf and floral tissues of F1 interspecific hybrids generated between the two closely related species of Arabidopsis thaliana and Arabidopsis lyrata with a whole-genome SNP tiling array (AtSNPtile1).
Project description:We analyzed allele-specific expression (ASE) in leaf and floral tissues of F1 interspecific hybrids generated between the two closely related species of Arabidopsis thaliana and Arabidopsis lyrata with a whole-genome SNP tiling array (AtSNPtile1). 24 sampes, 12 DNA samples from parents and hybrids, 12 RNA sample from leaf and flowers of hybrids
Project description:In plants, imprinted gene expression occurs in endosperm seed tissue and can be associated with differential DNA methylation between maternal and paternal alleles. Imprinting is theorized to have been selected for because of conflict between parental genomes in offspring, but most studies of imprinting have been conducted in Arabidopsis thaliana, an inbred primarily self-fertilizing species that should have limited parental conflict. We examined embryo and endosperm allele-specific expression and DNA methylation genome-wide in the wild outcrossing species Arabidopsis lyrata. Here we show that the majority of A. lyrata imprinted genes exhibit parentally-biased expression in A. thaliana, suggesting that there is evolutionary conservation in gene imprinting. Surprisingly, we discovered substantial interspecies differences in methylation features associated with paternally expressed imprinted genes (PEGs). Unlike A. thaliana, the maternal allele of many A. lyrata PEGs was hypermethylated in the CHG context. Increased maternal allele CHG methylation was associated with increased expression bias in favor of the paternal allele. We propose that CHG methylation maintains or reinforces repression of maternal alleles of PEGs. These data suggest that while the genes subject to imprinting are largely conserved, there is flexibility in the epigenetic mechanisms employed between closely related species to maintain monoallelic expression. This supports the idea that imprinting of specific genes is a functional phenomenon, and not simply a byproduct of seed epigenomic reprogramming.
Project description:In plants, imprinted gene expression occurs in endosperm seed tissue and can be associated with differential DNA methylation between maternal and paternal alleles. Imprinting is theorized to have been selected for because of conflict between parental genomes in offspring, but most studies of imprinting have been conducted in Arabidopsis thaliana, an inbred primarily self-fertilizing species that should have limited parental conflict. We examined embryo and endosperm allele-specific expression and DNA methylation genome-wide in the wild outcrossing species Arabidopsis lyrata. Here we show that the majority of A. lyrata imprinted genes exhibit parentally-biased expression in A. thaliana, suggesting that there is evolutionary conservation in gene imprinting. Surprisingly, we discovered substantial interspecies differences in methylation features associated with paternally expressed imprinted genes (PEGs). Unlike A. thaliana, the maternal allele of many A. lyrata PEGs was hypermethylated in the CHG context. Increased maternal allele CHG methylation was associated with increased expression bias in favor of the paternal allele. We propose that CHG methylation maintains or reinforces repression of maternal alleles of PEGs. These data suggest that while the genes subject to imprinting are largely conserved, there is flexibility in the epigenetic mechanisms employed between closely related species to maintain monoallelic expression. This supports the idea that imprinting of specific genes is a functional phenomenon, and not simply a byproduct of seed epigenomic reprogramming. Examination of total gene expression, parent-of-origin specific allelic bias, or DNA methylation in embryo, endosperm, flower bud or seedcoat tissue from Arabidopsis lyrata accessions MN47 (MN), Karhumaki (Kar or KA), and crosses between them. High-throughput Illumina poly-A-selected mRNA-seq was used to identify imprinted genes in A. lyrata, and high-throughput Illumina whole genome bisulfite-sequencing was used to examine DNA methylation. mRNA-seq samples are designated MMxFF_T# where MM is the mother of the cross (either MN for MN47 or KA for Kar), FF is the father, T is the tissue (E for embryo, N for endosperm, S for seedcoat, b for buds), and # is the replicate numbers. Samples obtained from bisulfite sequencing follow the same naming but have suffix _BS and indicate cytosine methylation context (CpG, CHG, or CHH). For KAxMN bisulfite sequencing, additional files MMxFF_T#_BS_P_C.txt follow the same naming scheme but contain context-specific methylation data (C) from reads that mapped preferentially to one parent strain (P).
Project description:We describe a method for identifying peptides that result from missense changes and identify peptides among 2 human brains that would have otherwise not been detected. Next, we use this data to estimate of allele-specific protein abundance in human brain for an average per individual, and to estimate apolipoprotein E allele specific abundance in human brain across individuals. Finally, we estimate the heritability of allele-specific protein abundance.
Project description:By comparing mouse fibroblasts from two parental strains (Bl6 and Spretus) with fibroblasts from their first generation offspring (F1) we can detect allele specific expression of proteins. The Bl6 and Spretus lines are evolutionary distant and harbour many SNPs in their genomes which when synonomous we can detect on the protein level using mass spectrometry. By mixing SILAC labeled Bl6, Spretus and F1 offspring cell lines we can detect peptides shared between all three cell lines and also SNP peptides that are only expressed in the F1 cells and either Bl6 or Spretus cells. By comparing the abundance of the shared peptides and the SNP peptides we can quantify how much of a protein in the F1 cells that comes from the paternal or maternal allele. This data were then further compared to polysome profiling data. Azidohomoalanine labeling was used to enrich newly synthesized proteins from the three cell lines.