Browsing by Subject "RNA-Seq"
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Item Open Access Evolutionary Divergence of Gene and Protein Expression in the Brains of Humans and Chimpanzees.(Genome Biol Evol, 2015-07-10) Bauernfeind, Amy L; Soderblom, Erik J; Turner, Meredith E; Moseley, M Arthur; Ely, John J; Hof, Patrick R; Sherwood, Chet C; Wray, Gregory A; Babbitt, Courtney CAlthough transcriptomic profiling has become the standard approach for exploring molecular differences in the primate brain, very little is known about how the expression levels of gene transcripts relate to downstream protein abundance. Moreover, it is unknown whether the relationship changes depending on the brain region or species under investigation. We performed high-throughput transcriptomic (RNA-Seq) and proteomic (liquid chromatography coupled with tandem mass spectrometry) analyses on two regions of the human and chimpanzee brain: The anterior cingulate cortex and caudate nucleus. In both brain regions, we found a lower correlation between mRNA and protein expression levels in humans and chimpanzees than has been reported for other tissues and cell types, suggesting that the brain may engage extensive tissue-specific regulation affecting protein abundance. In both species, only a few categories of biological function exhibited strong correlations between mRNA and protein expression levels. These categories included oxidative metabolism and protein synthesis and modification, indicating that the expression levels of mRNA transcripts supporting these biological functions are more predictive of protein expression compared with other functional categories. More generally, however, the two measures of molecular expression provided strikingly divergent perspectives into differential expression between human and chimpanzee brains: mRNA comparisons revealed significant differences in neuronal communication, ion transport, and regulatory processes, whereas protein comparisons indicated differences in perception and cognition, metabolic processes, and organization of the cytoskeleton. Our results highlight the importance of examining protein expression in evolutionary analyses and call for a more thorough understanding of tissue-specific protein expression levels.Item Open Access Expression level dominance and homeolog expression bias in recurrent origins of the allopolyploid fern polypodium hesperium(American Fern Journal, 2019-07-01) Sigel, EM; Der, JP; Windham, MD; Pryer, KM© 2019 American Fern Society. All rights reserved. Allopolyploidization is a common mode of speciation in ferns with many taxa having formed recurrently from distinct hybridization events between the same parent species. Each hybridization event marks the union of divergent parental gene copies, or homeologs, and the formation of an independently derived lineage. Little is known about the effects of recurrent origins on the genomic composition and phenotypic variation of allopolyploid fern taxa. To begin to address this knowledge gap, we investigated gene expression patterns in two naturally formed, independently derived lineages of the allotetraploid fern Polypodium hesperium relative to its diploid progenitor species, Polypodium amorphum and Polypodium glycyrrhiza. Using RNA-sequencing to survey total gene expression levels for 19194 genes and homeolog-specific expression for 1073 genes, we found that, in general, gene expression in both lineages of P. hesperium was biased toward P. amorphum - both by mirroring expression levels of P. amorphum and preferentially expressing homeologs derived from P. amorphum. However, we recovered substantial expression variation between the two lineages at the level of individual genes and among individual specimens. Our results align with similar transcriptome profile studies of angiosperms, suggesting that expression in many allopolyploid plants reflects the dominance of a specific parental subgenome, but that recurrent origins impart substantial expression, or phenotypic, variation to allopolyploid taxa.