Abstract
Dosage compensation has been thought to be a ubiquitous property of sex chromosomes that are represented differently in males and females. The expression of most X-borne genes is equalized between XX females and XY males in therian mammals (marsupials and "placentals") by inactivating one X chromosome in female somatic cells. However, compensation seems not to be strictly required to equalize the expression of most Z-borne genes between ZZ male and ZW female birds. Whether dosage compensation operates in the third mammal lineage, the egg-laying monotremes, is of considerable interest, since the platypus has a complex sex chromosome system in which five X and five Y chromosomes share considerable genetic hom*ology with the chicken ZW sex chromosome pair, but not with therian XY chromosomes. The assignment of genes to four platypus X chromosomes allowed us to examine X dosage compensation in this unique species. Quantitative PCR showed a range of compensation, but SNP analysis of several X-borne genes showed that both alleles are transcribed in a heterozygous female. Transcription of 14 BACs representing 19 X-borne genes was examined by RNA-FISH in female and male fibroblasts. An autosomal control gene was expressed from both alleles in nearly all nuclei, and four pseudoautosomal BACs were usually expressed from both alleles in male as well as female nuclei, showing that their Y loci are active. However, nine X-specific BACs were usually transcribed from only one allele. This suggests that while some genes on the platypus X are not dosage compensated, other genes do show some form of compensation via stochastic transcriptional inhibition, perhaps representing an ancestral system that evolved to be more tightly controlled in placental mammals such as human and mouse.
| Original language | English |
|---|---|
| Article number | e1000140 |
| Journal | PLoS Genetics |
| Volume | 4 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Jul 2008 |
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Deakin, J. E., Hore, T. A., Koina, E., & Marshall Graves, J. A. (2008). The status of dosage compensation in the multiple X chromosomes of the platypus. PLoS Genetics, 4(7), Article e1000140. https://doi.org/10.1371/journal.pgen.1000140
Deakin, Janine E. ; Hore, Timothy A. ; Koina, Edda et al. / The status of dosage compensation in the multiple X chromosomes of the platypus. In: PLoS Genetics. 2008 ; Vol. 4, No. 7.
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title = "The status of dosage compensation in the multiple X chromosomes of the platypus",
abstract = "Dosage compensation has been thought to be a ubiquitous property of sex chromosomes that are represented differently in males and females. The expression of most X-borne genes is equalized between XX females and XY males in therian mammals (marsupials and {"}placentals{"}) by inactivating one X chromosome in female somatic cells. However, compensation seems not to be strictly required to equalize the expression of most Z-borne genes between ZZ male and ZW female birds. Whether dosage compensation operates in the third mammal lineage, the egg-laying monotremes, is of considerable interest, since the platypus has a complex sex chromosome system in which five X and five Y chromosomes share considerable genetic hom*ology with the chicken ZW sex chromosome pair, but not with therian XY chromosomes. The assignment of genes to four platypus X chromosomes allowed us to examine X dosage compensation in this unique species. Quantitative PCR showed a range of compensation, but SNP analysis of several X-borne genes showed that both alleles are transcribed in a heterozygous female. Transcription of 14 BACs representing 19 X-borne genes was examined by RNA-FISH in female and male fibroblasts. An autosomal control gene was expressed from both alleles in nearly all nuclei, and four pseudoautosomal BACs were usually expressed from both alleles in male as well as female nuclei, showing that their Y loci are active. However, nine X-specific BACs were usually transcribed from only one allele. This suggests that while some genes on the platypus X are not dosage compensated, other genes do show some form of compensation via stochastic transcriptional inhibition, perhaps representing an ancestral system that evolved to be more tightly controlled in placental mammals such as human and mouse.",
author = "Deakin, {Janine E.} and Hore, {Timothy A.} and Edda Koina and {Marshall Graves}, {Jennifer A.}",
year = "2008",
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Deakin, JE, Hore, TA, Koina, E & Marshall Graves, JA 2008, 'The status of dosage compensation in the multiple X chromosomes of the platypus', PLoS Genetics, vol. 4, no. 7, e1000140. https://doi.org/10.1371/journal.pgen.1000140
The status of dosage compensation in the multiple X chromosomes of the platypus. / Deakin, Janine E.; Hore, Timothy A.; Koina, Edda et al.
In: PLoS Genetics, Vol. 4, No. 7, e1000140, 07.2008.
Research output: Contribution to journal › Article › peer-review
TY - JOUR
T1 - The status of dosage compensation in the multiple X chromosomes of the platypus
AU - Deakin, Janine E.
AU - Hore, Timothy A.
AU - Koina, Edda
AU - Marshall Graves, Jennifer A.
PY - 2008/7
Y1 - 2008/7
N2 - Dosage compensation has been thought to be a ubiquitous property of sex chromosomes that are represented differently in males and females. The expression of most X-borne genes is equalized between XX females and XY males in therian mammals (marsupials and "placentals") by inactivating one X chromosome in female somatic cells. However, compensation seems not to be strictly required to equalize the expression of most Z-borne genes between ZZ male and ZW female birds. Whether dosage compensation operates in the third mammal lineage, the egg-laying monotremes, is of considerable interest, since the platypus has a complex sex chromosome system in which five X and five Y chromosomes share considerable genetic hom*ology with the chicken ZW sex chromosome pair, but not with therian XY chromosomes. The assignment of genes to four platypus X chromosomes allowed us to examine X dosage compensation in this unique species. Quantitative PCR showed a range of compensation, but SNP analysis of several X-borne genes showed that both alleles are transcribed in a heterozygous female. Transcription of 14 BACs representing 19 X-borne genes was examined by RNA-FISH in female and male fibroblasts. An autosomal control gene was expressed from both alleles in nearly all nuclei, and four pseudoautosomal BACs were usually expressed from both alleles in male as well as female nuclei, showing that their Y loci are active. However, nine X-specific BACs were usually transcribed from only one allele. This suggests that while some genes on the platypus X are not dosage compensated, other genes do show some form of compensation via stochastic transcriptional inhibition, perhaps representing an ancestral system that evolved to be more tightly controlled in placental mammals such as human and mouse.
AB - Dosage compensation has been thought to be a ubiquitous property of sex chromosomes that are represented differently in males and females. The expression of most X-borne genes is equalized between XX females and XY males in therian mammals (marsupials and "placentals") by inactivating one X chromosome in female somatic cells. However, compensation seems not to be strictly required to equalize the expression of most Z-borne genes between ZZ male and ZW female birds. Whether dosage compensation operates in the third mammal lineage, the egg-laying monotremes, is of considerable interest, since the platypus has a complex sex chromosome system in which five X and five Y chromosomes share considerable genetic hom*ology with the chicken ZW sex chromosome pair, but not with therian XY chromosomes. The assignment of genes to four platypus X chromosomes allowed us to examine X dosage compensation in this unique species. Quantitative PCR showed a range of compensation, but SNP analysis of several X-borne genes showed that both alleles are transcribed in a heterozygous female. Transcription of 14 BACs representing 19 X-borne genes was examined by RNA-FISH in female and male fibroblasts. An autosomal control gene was expressed from both alleles in nearly all nuclei, and four pseudoautosomal BACs were usually expressed from both alleles in male as well as female nuclei, showing that their Y loci are active. However, nine X-specific BACs were usually transcribed from only one allele. This suggests that while some genes on the platypus X are not dosage compensated, other genes do show some form of compensation via stochastic transcriptional inhibition, perhaps representing an ancestral system that evolved to be more tightly controlled in placental mammals such as human and mouse.
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U2 - 10.1371/journal.pgen.1000140
DO - 10.1371/journal.pgen.1000140
M3 - Article
SN - 1553-7390
VL - 4
JO - PLoS Genetics
JF - PLoS Genetics
IS - 7
M1 - e1000140
ER -
Deakin JE, Hore TA, Koina E, Marshall Graves JA. The status of dosage compensation in the multiple X chromosomes of the platypus. PLoS Genetics. 2008 Jul;4(7):e1000140. doi: 10.1371/journal.pgen.1000140
