scholarly journals Constraint and divergence of global gene expression in the mammalian embryo

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Noah Spies ◽  
Cheryl L Smith ◽  
Jesse M Rodriguez ◽  
Julie C Baker ◽  
Serafim Batzoglou ◽  
...  

The effects of genetic variation on gene regulation in the developing mammalian embryo remain largely unexplored. To globally quantify these effects, we crossed two divergent mouse strains and asked how genotype of the mother or of the embryo drives gene expression phenotype genomewide. Embryonic expression of 331 genes depends on the genotype of the mother. Embryonic genotype controls allele-specific expression of 1594 genes and a highly overlapping set of cis-expression quantitative trait loci (eQTL). A marked paucity of trans-eQTL suggests that the widespread expression differences do not propagate through the embryonic gene regulatory network. The cis-eQTL genes exhibit lower-than-average evolutionary conservation and are depleted for developmental regulators, consistent with purifying selection acting on expression phenotype of pattern formation genes. The widespread effect of maternal and embryonic genotype in conjunction with the purifying selection we uncovered suggests that embryogenesis is an important and understudied reservoir of phenotypic variation.

2019 ◽  
Author(s):  
Zhi Li ◽  
Peng Zhou ◽  
Rafael Della Coletta ◽  
Tifu Zhang ◽  
Alex B. Brohammer ◽  
...  

AbstractMaize exhibits tremendous gene expression variation between different lines. Complementation of diverse gene expression patterns in hybrids could play an important role in the manifestation of heterosis. In this study, we used transcriptome data of five different tissues from 33 maize inbreds and 89 hybrids (430 samples in total) to survey the global gene expression landscape of F1-hybrids relative to their inbred parents. Analysis of this data set revealed that single parent expression (SPE), which is defined as gene expression in only one of the two parents, while commonly observed, is highly genotype- and tissue-specific. Genes that have SPE in at least one pair of inbreds also tend to be tissue-specific. Genes with SPE caused by genomic presence/absence variation (PAV SPE) are much more frequently expressed in hybrids than genes that are present in the genome of both inbreds, but expressed in only a single-parent (non-PAV SPE) (74.7% vs. 59.7%). For non-PAV SPE genes, allele specific expression was used to investigate whether parental alleles not expressed in the inbred line (“silent allele”) can be actively transcribed in the hybrid. We found that expression of the silent allele in the hybrid is relatively rare (∼6.3% of non-PAV SPE genes), but is observed in almost all hybrids and tissues. Non-PAV SPE genes with expression of the silent allele in the hybrid are more likely to exhibit above high-parent expression level in the hybrid than those that do not express the silent allele. Finally, both PAV SPE and non-PAV SPE genes are highly enriched for being classified as non-syntenic, but depleted for curated genes with experimentally determined functions. This study provides a more comprehensive understanding of the potential role of non-PAV SPE and PAV SPE genes in heterosis.


Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 225 ◽  
Author(s):  
Katya Mack ◽  
Megan Phifer-Rixey ◽  
Bettina Harr ◽  
Michael Nachman

Interactions between genes can influence how selection acts on sequence variation. In gene regulatory networks, genes that affect the expression of many other genes may be under stronger evolutionary constraint than genes whose expression affects fewer partners. While this has been studied for individual tissue types, we know less about the effects of regulatory networks on gene evolution across different tissue types. We use RNA-sequencing and genomic data collected from Mus musculus domesticus to construct and compare gene co-expression networks for 10 tissue types. We identify tissue-specific expression and local regulatory variation, and we associate these components of gene expression variation with sequence polymorphism and divergence. We found that genes with higher connectivity across tissues and genes associated with a greater number of cross-tissue modules showed significantly lower genetic diversity and lower rates of protein evolution. Consistent with this pattern, “hub” genes across multiple tissues also showed evidence of greater evolutionary constraint. Using allele-specific expression, we found that genes with cis-regulatory variation had lower average connectivity and higher levels of tissue specificity. Taken together, these results are consistent with strong purifying selection acting on genes with high connectivity within and across tissues.


2018 ◽  
Vol 115 (47) ◽  
pp. E11081-E11090 ◽  
Author(s):  
Ryan A. York ◽  
Chinar Patil ◽  
Kawther Abdilleh ◽  
Zachary V. Johnson ◽  
Matthew A. Conte ◽  
...  

Many behaviors are associated with heritable genetic variation [Kendler and Greenspan (2006) Am J Psychiatry 163:1683–1694]. Genetic mapping has revealed genomic regions or, in a few cases, specific genes explaining part of this variation [Bendesky and Bargmann (2011) Nat Rev Gen 12:809–820]. However, the genetic basis of behavioral evolution remains unclear. Here we investigate the evolution of an innate extended phenotype, bower building, among cichlid fishes of Lake Malawi. Males build bowers of two types, pits or castles, to attract females for mating. We performed comparative genome-wide analyses of 20 bower-building species and found that these phenotypes have evolved multiple times with thousands of genetic variants strongly associated with this behavior, suggesting a polygenic architecture. Remarkably, F1 hybrids of a pit-digging and a castle-building species perform sequential construction of first a pit and then a castle bower. Analysis of brain gene expression in these hybrids showed that genes near behavior-associated variants display behavior-dependent allele-specific expression with preferential expression of the pit-digging species allele during pit digging and of the castle-building species allele during castle building. These genes are highly enriched for functions related to neurodevelopment and neural plasticity. Our results suggest that natural behaviors are associated with complex genetic architectures that alter behavior via cis-regulatory differences whose effects on gene expression are specific to the behavior itself.


2017 ◽  
Vol 152 (5) ◽  
pp. S29
Author(s):  
Evan S. Dellon ◽  
Sara R. Selitsky ◽  
Robert M. Genta ◽  
Richard H. Lash ◽  
Joel S. Parker

2020 ◽  
Author(s):  
Nil Aygün ◽  
Angela L. Elwell ◽  
Dan Liang ◽  
Michael J. Lafferty ◽  
Kerry E. Cheek ◽  
...  

SummaryInterpretation of the function of non-coding risk loci for neuropsychiatric disorders and brain-relevant traits via gene expression and alternative splicing is mainly performed in bulk post-mortem adult tissue. However, genetic risk loci are enriched in regulatory elements of cells present during neocortical differentiation, and regulatory effects of risk variants may be masked by heterogeneity in bulk tissue. Here, we map e/sQTLs and allele specific expression in primary human neural progenitors (n=85) and their sorted neuronal progeny (n=74). Using colocalization and TWAS, we uncover cell-type specific regulatory mechanisms underlying risk for these traits.


2015 ◽  
Author(s):  
Noah Spies ◽  
Cheryl L Smith ◽  
Jesse M Rodriguez ◽  
Julie C Baker ◽  
Serafim Batzoglou ◽  
...  

2019 ◽  
Author(s):  
Qiong Wang ◽  
Yaxiong Jia ◽  
Yuan Wang ◽  
Zhihua Jiang ◽  
Xiang Zhou ◽  
...  

Abstract Background: Gene expression variation is an important mechanism underlying phenotypic variation, and can occur via cis- and trans-regulation. In order to understand the role of cis- and trans-regulatory variation on population divergence of chicken, we developed reciprocal crosses of two chicken breeds, White Leghorn and Cornish Game, with major differences in body size and reproductive traits, and used them to identify the degree of cis versus trans variation in brain, liver and muscle of both male and female samples at 1 day age. Results: We provided a landscape about how the transcriptomes are regulated in the hybrid progenies of two contrasted breeds by allele specific expression analysis. Our results showed that compared with the cis-regulatory divergence, trans-acted genes existed more extensively in the chicken genome. Furthermore, a widespread tendency of compensatory regulation exists in chicken genome. Most importantly, we found the evidence of stronger purifying selection on genes regulated by trans variations than the cis elements. Conclusions: We demonstrated a pipeline to explore the allele-specific expression in the hybrid progenies of inbred lines without specific reference genome. Our research performed the first study to describe the regulatory divergence between two contrasted breeds. The results suggested that artificial selection associated with domestication in chicken may have more often acted on trans-regulatory divergence than cis.


2020 ◽  
Vol 111 (6) ◽  
pp. 539-547
Author(s):  
Sumaetee Tangwancharoen ◽  
Brice X Semmens ◽  
Ronald S Burton

Abstract Geographic variation in environmental temperature can select for local adaptation among conspecific populations. Divergence in gene expression across the transcriptome is a key mechanism for evolution of local thermal adaptation in many systems, yet the genetic mechanisms underlying this regulatory evolution remain poorly understood. Here we examine gene expression in 2 locally adapted Tigriopus californicus populations (heat tolerant San Diego, SD, and less tolerant Santa Cruz, SC) and their F1 hybrids during acute heat stress response. Allele-specific expression (ASE) in F1 hybrids was used to determine cis-regulatory divergence. We found that the number of genes showing significant allelic imbalance increased under heat stress compared to unstressed controls. This suggests that there is significant population divergence in cis-regulatory elements underlying heat stress response. Specifically, the number of genes showing an excess of transcripts from the more thermal tolerant (SD) population increased with heat stress while that number of genes with an SC excess was similar in both treatments. Inheritance patterns of gene expression also revealed that genes displaying SD-dominant expression phenotypes increase in number in response to heat stress; that is, across loci, gene expression in F1’s following heat stress showed more similarity to SD than SC, a pattern that was absent in the control treatment. The observed patterns of ASE and inheritance of gene expression provide insight into the complex processes underlying local adaptation and thermal stress response.


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