Dataset Information

The effect of transposable element insertions on gene expression evolution in rodents.

ABSTRACT:

Background

Many genomes contain a substantial number of transposable elements (TEs), a few of which are known to be involved in regulating gene expression. However, recent observations suggest that TEs may have played a very important role in the evolution of gene expression because many conserved non-genic sequences, some of which are know to be involved in gene regulation, resemble TEs.

Results

Here we investigate whether new TE insertions affect gene expression profiles by testing whether gene expression divergence between mouse and rat is correlated to the numbers of new transposable elements inserted near genes. We show that expression divergence is significantly correlated to the number of new LTR and SINE elements, but not to the numbers of LINEs. We also show that expression divergence is not significantly correlated to the numbers of ancestral TEs in most cases, which suggests that the correlations between expression divergence and the numbers of new TEs are causal in nature. We quantify the effect and estimate that TE insertion has accounted for approximately 20% (95% confidence interval: 12% to 26%) of all expression profile divergence in rodents.

Conclusions

We conclude that TE insertions may have had a major impact on the evolution of gene expression levels in rodents.

SUBMITTER: Pereira V

PROVIDER: S-EPMC2629548 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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Publications

The effect of transposable element insertions on gene expression evolution in rodents.

Pereira Vini V Enard David D Eyre-Walker Adam A

PloS one 20090202 2

<h4>Background</h4>Many genomes contain a substantial number of transposable elements (TEs), a few of which are known to be involved in regulating gene expression. However, recent observations suggest that TEs may have played a very important role in the evolution of gene expression because many conserved non-genic sequences, some of which are know to be involved in gene regulation, resemble TEs.<h4>Results</h4>Here we investigate whether new TE insertions affect gene expression profiles by test ...[more]

PMID: 19183808

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Project description:Gene expression dynamics is a key component of polyploid evolution, varying in nature, intensity, and temporal scales, most particularly in allopolyploids, where two or more sub-genomes from differentiated parental species and different repeat contents are merged. Here, we investigated transcriptome evolution at different evolutionary time scales among tetraploid, hexaploid, and neododecaploid Spartina species (Poaceae, Chloridoideae) that successively diverged in the last 6-10 my, at the origin of differential phenotypic and ecological traits. Of particular interest are the recent (19th century) hybridizations between the two hexaploids Spartina alterniflora (2n = 6x = 62) and S. maritima (2n = 6x = 60) that resulted in two sterile F1 hybrids: Spartina × townsendii (2n = 6x = 62) in England and Spartina × neyrautii (2n = 6x = 62) in France. Whole genome duplication of S. × townsendii gave rise to the invasive neo-allododecaploid species Spartina anglica (2n = 12x = 124). New transcriptome assemblies and annotations for tetraploids and the enrichment of previously published reference transcriptomes for hexaploids and the allododecaploid allowed identifying 42,423 clusters of orthologs and distinguishing 21 transcribed transposable element (TE) lineages across the seven investigated Spartina species. In 4x and 6x mesopolyploids, gene and TE expression changes were consistent with phylogenetic relationships and divergence, revealing weak expression differences in the tetraploid sister species Spartina bakeri and Spartina versicolor (<2 my divergence time) compared to marked transcriptome divergence between the hexaploids S. alterniflora and S. maritima that diverged 2-4 mya. Differentially expressed genes were involved in glycolysis, post-transcriptional protein modifications, epidermis development, biosynthesis of carotenoids. Most detected TE lineages (except SINE elements) were found more expressed in hexaploids than in tetraploids, in line with their abundance in the corresponding genomes. Comparatively, an astonishing (52%) expression repatterning and deviation from parental additivity were observed following recent reticulate evolution (involving the F1 hybrids and the neo-allododecaploid S. anglica), with various patterns of biased homoeologous gene expression, including genes involved in epigenetic regulation. Downregulation of TEs was observed in both hybrids and accentuated in the neo-allopolyploid. Our results reinforce the view that allopolyploidy represents springboards to new regulatory patterns, offering to worldwide invasive species, such as S. anglica, the opportunity to colonize stressful and fluctuating environments on saltmarshes.

Project description:Reviewing the genetics underlying the arms race between bacteria and bacteriophages can offer an interesting insight into the development of bacterial resistance and phage co-evolution. This study shows how the natural development of resistances to the K1F bacteriophage, a phage which targets the K1 capsule of pathogenic Escherichia coli, can come about through insertion sequences (IS). Of the K1F resistant mutants isolated, two were of particular interest. The first of these showed full resistance to K1F and was found to have disruptions to kpsE, the product of which is involved in polysialic acid translocation. The second, after showing an initial susceptibility to K1F which then developed to full resistance, had disruptions to neuC, a gene involved in one of the early steps of polysialic acid biosynthesis. Both of these mutations came with a fitness cost and produced considerable phenotypic differences in the completeness and location of the K1 capsule when compared with the wild type. Sequential treatment of these two K1F resistant mutants with T7 resulted in the production of a variety of isolates, many of which showed a renewed susceptibility to K1F, indicating that these insertion sequence mutations are reversible, as well as one isolate that developed resistance to both phages. IMPORTANCE Bacteriophages have many potential uses in industry and the clinical environment as an antibacterial control measure. One of their uses, phage therapy, is an appealing alternative to antibiotics due to their high specificity. However, as with the rise in antimicrobial resistance (AMR), it is critical to improve our understanding of how resistance develops against these viral agents. In the same way as bacteria will evolve and mutate antibiotic receptors so they can no longer be recognized, resistance to bacteriophages can come about via mutations to phage receptors, preventing phage binding and infection. We have shown that Escherichia coli will become resistant to the K1F bacteriophage via insertion element reshufflings causing null mutations to elements of the polysialic acid biosynthetic cluster. Exposure to the T7 bacteriophage then resulted in further changes in the position of these IS elements, further altering their resistance and sensitivity profiles.

Dataset Information

The effect of transposable element insertions on gene expression evolution in rodents.

Background

Results

Conclusions

Publications

The effect of transposable element insertions on gene expression evolution in rodents.

Similar Datasets

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