scholarly journals Regulatory remodeling in the allo-tetraploid frog Xenopus laevis

2017 ◽  
Author(s):  
Dei M. Elurbe ◽  
Sarita S. Paranjpe ◽  
Georgios Georgiou ◽  
Ila van Kruijsbergen ◽  
Ozren Bogdanovic ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Regulatory Elements ◽  
Whole Genome ◽  
Dna Repeats ◽  
Vertebrate Genome ◽  
Closely Related Species ◽  
Flanking Regions ◽  
Regulatory Landscape

AbstractBackgroundGenome duplication has played a pivotal role in the evolution of many eukaryotic lineages, including the vertebrates. The most recent vertebrate genome duplication is that in Xenopus laevis, resulting from the hybridization of two closely related species about 17 million years ago [1]. However, little is known about the consequences of this duplication at the level of the genome, the epigenome and gene expression.ResultsOf the parental subgenomes, S chromosomes have degraded faster than L chromosomes ever since the genome duplication and until the present day. Deletions appear to have the largest effect on pseudogene formation and loss of regulatory regions. Deleted regions are enriched for long DNA repeats and the flanking regions have high alignment scores, suggesting that non-allelic homologous recombination (NAHR) has played a significant role in the loss of DNA. To assess innovations in the X. laevis subgenomes we examined p300 (Ep300)-bound enhancer peaks that are unique to one subgenome and absent from X. tropicalis. A large majority of new enhancers are comprised of transposable elements. Finally, to dissect early and late events following interspecific hybridization, we examined the epigenome and the enhancer landscape in X. tropicalis × X. laevis hybrid embryos. Strikingly, young X. tropicalis DNA transposons are derepressed and recruit p300 in hybrid embryos.ConclusionsThe results show that erosion of X. laevis genes and functional regulatory elements is associated with repeats and NAHR, and furthermore that young repeats have also contributed to the p300-bound regulatory landscape following hybridization and whole genome duplication.

Phylogenetic Analysis of T-Box Genes Demonstrates the Importance of Amphioxus for Understanding Evolution of the Vertebrate Genome

Genetics ◽  
2000 ◽  
Vol 156 (3) ◽  
pp. 1249-1257
Author(s):  
Ilya Ruvinsky ◽  
Lee M Silver ◽  
Jeremy J Gibson-Brown
Keyword(s):  
Phylogenetic Analysis ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Gene Families ◽  
Vertebrate Evolution ◽  
Whole Genome ◽  
Vertebrate Genome ◽  
T Box ◽  
Genetic Complexity ◽  
History Of

Abstract The duplication of preexisting genes has played a major role in evolution. To understand the evolution of genetic complexity it is important to reconstruct the phylogenetic history of the genome. A widely held view suggests that the vertebrate genome evolved via two successive rounds of whole-genome duplication. To test this model we have isolated seven new T-box genes from the primitive chordate amphioxus. We find that each amphioxus gene generally corresponds to two or three vertebrate counterparts. A phylogenetic analysis of these genes supports the idea that a single whole-genome duplication took place early in vertebrate evolution, but cannot exclude the possibility that a second duplication later took place. The origin of additional paralogs evident in this and other gene families could be the result of subsequent, smaller-scale chromosomal duplications. Our findings highlight the importance of amphioxus as a key organism for understanding evolution of the vertebrate genome.

Evidence in favour of ancient octaploidy in the vertebrate genome

2000 ◽  
Vol 28 (2) ◽  
pp. 259-264 ◽  
Author(s):  
T.J. Gibson ◽  
J. Spring
Keyword(s):  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Whole Genome ◽  
Vertebrate Genome ◽  
Gene Trees ◽  
Paralogous Gene ◽  
Linkage Groups ◽  
Vertebrate Lineage ◽  
Eyes Absent ◽  
Show Evidence

Vertebrate genomes are larger than invertebrates and show evidence of extensive gene duplication, including many collinear chromosomal segments. On the basis of this intra-genomic synteny, it has been proposed that two rounds of whole genome duplication (octaploidy) occurred early in the vertebrate lineage. Recently, this early vertebrate octaploidy has been challenged on the basis of gene trees. We report new linkage groups encompassing the matrilin (MATN), syndecan (SDC), Eyes Absent (EYA), HCK kinase and SRC kinase paralogous gene quartets. In contrast to other studies, the sequence trees are weakly supportive of ancient octaploidy. It is concluded that there is no strong evidence against the octaploidy, provided that consecutive genome duplication was rapid.

scholarly journals The neutral rate of whole-genome duplication varies among yeast species and their hybrids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Marsit ◽  
M. Hénault ◽  
G. Charron ◽  
A. Fijarczyk ◽  
C. R. Landry
Keyword(s):  
Natural Selection ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Yeast Species ◽  
Whole Genome ◽  
Hybrid Speciation ◽  
Relaxed Selection ◽  
Confounding Effect ◽  
Closely Related Species ◽  
Adaptive Mutations

AbstractHybridization and polyploidization are powerful mechanisms of speciation. Hybrid speciation often coincides with whole-genome duplication (WGD) in eukaryotes. This suggests that WGD may allow hybrids to thrive by increasing fitness, restoring fertility and/or increasing access to adaptive mutations. Alternatively, it has been suggested that hybridization itself may trigger WGD. Testing these models requires quantifying the rate of WGD in hybrids without the confounding effect of natural selection. Here we show, by measuring the spontaneous rate of WGD of more than 1300 yeast crosses evolved under relaxed selection, that some genotypes or combinations of genotypes are more prone to WGD, including some hybrids between closely related species. We also find that higher WGD rate correlates with higher genomic instability and that WGD increases fertility and genetic variability. These results provide evidence that hybridization itself can promote WGD, which in turn facilitates the evolution of hybrids.

NAI2 and TSA1 Drive Differentiation of Constitutive and Inducible ER Body Formation in Brassicaceae

2019 ◽  
Vol 61 (4) ◽  
pp. 722-734 ◽  
Author(s):  
Natalia Stefanik ◽  
Jakub Bizan ◽  
Alwine Wilkens ◽  
Katarzyna Tarnawska-Glatt ◽  
Shino Goto-Yamada ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Whole Genome ◽  
Promoter Regions ◽  
Closely Related Species ◽  
Defense Strategies ◽  
Body Formation ◽  
Different Types

Abstract Brassicaceae and closely related species develop unique endoplasmic reticulum (ER)-derived structures called ER bodies, which accumulate β-glucosidases/myrosinases that are involved in chemical defense. There are two different types of ER bodies: ER bodies constitutively present in seedlings (cER bodies) and ER bodies in rosette leaves induced by treatment with the wounding hormone jasmonate (JA) (iER bodies). Here, we show that At-α whole-genome duplication (WGD) generated the paralogous genes NAI2 and TSA1, which consequently drive differentiation of cER bodies and iER bodies in Brassicaceae plants. In Arabidopsis, NAI2 is expressed in seedlings where cER bodies are formed, whereas TSA1 is expressed in JA-treated leaves where iER bodies are formed. We found that the expression of NAI2 in seedlings and the JA inducibility of TSA1 are conserved across other Brassicaceae plants. The accumulation of NAI2 transcripts in Arabidopsis seedlings is dependent on the transcription factor NAI1, whereas the JA induction of TSA1 in rosette leaves is dependent on MYC2, MYC3 and MYC4. We discovered regions of microsynteny, including the NAI2/TSA1 genes, but the promoter regions are differentiated between TSA1 and NAI2 genes in Brassicaceae. This suggests that the divergence of function between NAI2 and TSA1 occurred immediately after WGD in ancestral Brassicaceae plants to differentiate the formation of iER and cER bodies. Our findings indicate that At-α WGD enabled diversification of defense strategies, which may have contributed to the massive diversification of Brassicaceae plants.

scholarly journals Genetic drift dominates genome-wide regulatory evolution following an ancient whole genome duplication in Atlantic salmon

2020 ◽  
Author(s):  
Jukka-Pekka Verta ◽  
Henry Barton ◽  
Victoria Pritchard ◽  
Craig Primmer
Keyword(s):  
Atlantic Salmon ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Regulatory Elements ◽  
Functional Redundancy ◽  
Neutral Evolution ◽  
Whole Genome ◽  
Regulatory Evolution ◽  
Whole Genome Duplications ◽  
Genome Duplications

AbstractWhole genome duplications (WGD) have been considered as springboards that potentiate lineage diversification through increasing functional redundancy. Divergence in gene regulatory elements is a central mechanism for evolutionary diversification, yet the patterns and processes governing regulatory divergence following events that lead to massive functional redundancy, such as WGD, remain largely unknown. We studied the patterns of divergence and strength of natural selection on regulatory elements in the Atlantic salmon (Salmo salar) genome, which has undergone WGD 100-80 Mya. Using ChIPmentation, we first show that H3K27ac, a histone modification typical to enhancers and promoters, is associated with genic regions, tissue specific transcription factor binding motifs, and with gene transcription levels in immature testes. Divergence in transcription between duplicated genes from WGD (ohnologs) correlated with difference in the number of proximal regulatory elements, but not with promoter elements, suggesting that functional divergence between ohnologs after WGD is mainly driven by enhancers. By comparing H3K27ac regions between duplicated genome blocks, we further show that a longer polyploid state post-WGD has constrained asymmetric regulatory evolution. Patterns of genetic diversity across natural populations inferred from re-sequencing indicate that recent evolutionary pressures on H3K27ac regions are dominated by largely neutral evolution. In sum, our results suggest that post-WGD functional redundancy in regulatory elements continues to have an impact on the evolution of the salmon genome, promoting largely neutral evolution of regulatory elements despite their association with transcription levels. These results highlight a case where genome-wide regulatory evolution following an ancient WGD is dominated by genetic drift.Significance statementRegulatory evolution following whole genome duplications (WGD) has been investigated at the gene expression level, but studies of the regulatory elements that control expression have been lacking. By investigating regulatory elements in the Atlantic salmon genome, which has undergone a whole genome duplication 100-80 million years ago, we discovered patterns suggesting that neutral divergence is the prevalent mode of regulatory element evolution post-WGD. Our results suggest mechanisms for explaining the prevalence of asymmetric gene expression evolution following whole genome duplication, as well as the mismatch between evolutionary rates in enhancers versus that of promoters.

scholarly journals Homoeologous chromosomes of Xenopus laevis are highly conserved after whole-genome duplication

Heredity ◽  
2013 ◽  
Vol 111 (5) ◽  
pp. 430-436 ◽  
Author(s):  
Y Uno ◽  
C Nishida ◽  
C Takagi ◽  
N Ueno ◽  
Y Matsuda
Keyword(s):  
Xenopus Laevis ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Whole Genome ◽  
Homoeologous Chromosomes

scholarly journals Regions enriched for DNA repeats in chromosomes of Macrostomum mirumnovem, a species with a recent Whole Genome Duplication

2020 ◽  
Vol 24 (6) ◽  
pp. 636-642
Author(s):  
K. S. Zadesenets ◽  
N. B. Rubtsov
Keyword(s):  
Whole Genome Duplication ◽  
Genome Duplication ◽  
B Chromosome ◽  
Dna Probes ◽  
B Chromosomes ◽  
Large Chromosome ◽  
Whole Genome ◽  
Dna Repeats ◽  
Fluorescent Signal ◽  
Chromosome Regions

The free-living flatworm Macrostomum mirumnovem is a neopolyploid species whose genome underwent a recent Whole Genome Duplication (WGD). In the result of chromosome fusions of the ancient haploid chromosome set, large metacentric chromosomes were formed. In addition to three pairs of small metacentrics, the current karyotype of M. mirumnovem contains two pairs of large metacentric chromosomes, MMI1 and MMI2. The generation of microdissected DNA libraries enriched for DNA repeats followed by DNA probe preparation and fluorescent in situ hybridization (FISH) were performed. The DNA probes obtained marked chromosome regions enriched for different DNA repeats in the M. mirumnovem chromosomes. The size and localization of these regions varied in different copies of large chromosomes. They varied even in homologous chromosomes, suggesting their divergence due to genome re-diploidization after a WGD. Besides the newly formed chromosome regions enriched for DNA repeats, B chromosomes were found in the karyotypes of the studied specimens of M. mirumnovem. These B chromosomes varied in size and morphology. FISH with microdissected DNA probes revealed that some Bs had a distinct DNA content. FISH could paint differently B chromosomes in different worms and even in the same sample. B chromosomes could carry a bright specific fluorescent signal or could show no fluorescent signal at all. In latter cases, the specific FISH signal could be absent even in the pericentromeric region of the B chromosome. Possible mechanisms of B chromosome formation and their further evolution are discussed. The results obtained indicate an important role that repetitive DNAs play in genome re-diploidization initiating a rapid differentiation of large chromosome copies. Taking together, karyotype peculiarities (a high level of intraspecific karyotypic diversity associated with chromosome number variation, structural chromosomal rearrangements, and the formation of new regions enriched for DNA repeats) and some phenotypic features of M. mirumnovem (small body size, short lifecycle, easy maintenance in the laboratory) make this species a perspective model in the studies of genomic and karyotypic evolution in species passed through a recent WGD event.

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