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A genomic duplication is associated with ectopic eomesodermin expression in the embryonic chicken comb and two duplex-comb phenotypes.

Dorshorst B, Harun-Or-Rashid M, Bagherpoor AJ, Rubin CJ, Ashwell C, Gourichon D, Tixier-Boichard M, Hallböök F, Andersson L - PLoS Genet. (2015)

Bottom Line: Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES).In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos.We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event.

View Article: PubMed Central - PubMed

Affiliation: Science for Life Laboratory, Dept. of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Dept. of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia, United States of America.

ABSTRACT
Duplex-comb (D) is one of three major loci affecting comb morphology in the domestic chicken. Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation. In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos. The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rose-comb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme. Interestingly, the causal mutations of all three major comb loci in the chicken are now known to be composed of large-scale structural genomic variants that each result in ectopic expression of transcription factors. The Duplex-comb locus also illustrates the evolution of alleles in domestic animals, which means that alleles evolve by the accumulation of two or more consecutive mutations affecting the phenotype. We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event.

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Related in: MedlinePlus

EOMES expression is increased in D*V embryonic comb tissue.Results of qRT-PCR analysis demonstrating increased EOMES expression in D*V embryonic comb tissue whereas CMC1 and AZI2, located nearby the duplicated region, do not show any significant change in expression. Bar graphs mean ±sem, ANOVA, *P<0.05, **P<0.001, ***P<0.0001.
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pgen.1004947.g003: EOMES expression is increased in D*V embryonic comb tissue.Results of qRT-PCR analysis demonstrating increased EOMES expression in D*V embryonic comb tissue whereas CMC1 and AZI2, located nearby the duplicated region, do not show any significant change in expression. Bar graphs mean ±sem, ANOVA, *P<0.05, **P<0.001, ***P<0.0001.

Mentions: The expression pattern of candidate genes located in the proximity of the 20 Kb duplication was investigated using quantitative reverse transcription-PCR (qRT-PCR) in samples of comb tissue from developing chicken embryos. The duplication is located within an intron of CMC1 encoding COX assembly mitochondrial protein homolog (S. cerevisiae) as assessed by aligning the predicted CMC1 sequence (XM_418758.4) to the chicken genome via BLAT in the UCSC genome browser. 5-azacytidine induced 2 (AZI2) is the nearest gene on the 3’ side of the duplication and eomesodermin (EOMES) is the nearest gene on the 5’ side. CMC1 and AZI2 were both expressed in comb tissue but did not show any significant difference in expression between genotypes. In contrast, EOMES showed a dramatic expression difference between genotypes and was more highly expressed at E8, E9 and E12 in D*V embryonic comb as compared to D*N, while it was not expressed in any genotype at E18 (Fig. 3).


A genomic duplication is associated with ectopic eomesodermin expression in the embryonic chicken comb and two duplex-comb phenotypes.

Dorshorst B, Harun-Or-Rashid M, Bagherpoor AJ, Rubin CJ, Ashwell C, Gourichon D, Tixier-Boichard M, Hallböök F, Andersson L - PLoS Genet. (2015)

EOMES expression is increased in D*V embryonic comb tissue.Results of qRT-PCR analysis demonstrating increased EOMES expression in D*V embryonic comb tissue whereas CMC1 and AZI2, located nearby the duplicated region, do not show any significant change in expression. Bar graphs mean ±sem, ANOVA, *P<0.05, **P<0.001, ***P<0.0001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4366209&req=5

pgen.1004947.g003: EOMES expression is increased in D*V embryonic comb tissue.Results of qRT-PCR analysis demonstrating increased EOMES expression in D*V embryonic comb tissue whereas CMC1 and AZI2, located nearby the duplicated region, do not show any significant change in expression. Bar graphs mean ±sem, ANOVA, *P<0.05, **P<0.001, ***P<0.0001.
Mentions: The expression pattern of candidate genes located in the proximity of the 20 Kb duplication was investigated using quantitative reverse transcription-PCR (qRT-PCR) in samples of comb tissue from developing chicken embryos. The duplication is located within an intron of CMC1 encoding COX assembly mitochondrial protein homolog (S. cerevisiae) as assessed by aligning the predicted CMC1 sequence (XM_418758.4) to the chicken genome via BLAT in the UCSC genome browser. 5-azacytidine induced 2 (AZI2) is the nearest gene on the 3’ side of the duplication and eomesodermin (EOMES) is the nearest gene on the 5’ side. CMC1 and AZI2 were both expressed in comb tissue but did not show any significant difference in expression between genotypes. In contrast, EOMES showed a dramatic expression difference between genotypes and was more highly expressed at E8, E9 and E12 in D*V embryonic comb as compared to D*N, while it was not expressed in any genotype at E18 (Fig. 3).

Bottom Line: Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES).In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos.We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event.

View Article: PubMed Central - PubMed

Affiliation: Science for Life Laboratory, Dept. of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Dept. of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia, United States of America.

ABSTRACT
Duplex-comb (D) is one of three major loci affecting comb morphology in the domestic chicken. Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation. In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos. The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rose-comb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme. Interestingly, the causal mutations of all three major comb loci in the chicken are now known to be composed of large-scale structural genomic variants that each result in ectopic expression of transcription factors. The Duplex-comb locus also illustrates the evolution of alleles in domestic animals, which means that alleles evolve by the accumulation of two or more consecutive mutations affecting the phenotype. We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event.

Show MeSH
Related in: MedlinePlus