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Michael B Thompson - One of the best experts on this subject based on the ideXlab platform.
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uterine epithelial remodelling during pregnancy in the Marsupial monodelphis domestica didelphidae implications for mammalian placental evolution
Journal of Anatomy, 2020Co-Authors: Melanie K Laird, Christopher R Murphy, Bronwyn M Mcallan, Victoria L Hansen, Michael B ThompsonAbstract:Mammalian pregnancy involves remodelling of the uterine epithelium to enable placentation. In Marsupials, such remodelling has probably played a key role in the transition from ancestral invasive placentation to non-invasive placentation. Identifying uterine alterations that are unique to Marsupials with non-invasive placentation can thus elucidate mechanisms of Marsupial placental evolution. We identified apical alterations to uterine epithelial cells prior to implantation in Monodelphis domestica, a member of the least derived living Marsupial clade (Didelphidae) with invasive (endotheliochorial) placentation. We then compared these traits with those of Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae), both with non-invasive placentation, to identify which alterations to the uterine epithelium are ancestral and which facilitate secondarily evolved non-invasive placentation. In M. domestica, remodelling of the uterine epithelium involves reduced cellular heterogeneity and development of uterodome-like cells, suggesting that similar alterations may also have occurred in the Marsupial common ancestor. These alterations also overlap with those of both T. vulpecula and Ma. eugenii, suggesting that the placental shift from invasive to non-invasive placentation in Marsupials involves essential, conserved characteristics, irrespective of placental mode. However, unique apical alterations of both T. vulpecula and Ma. eugenii, relative to M. domestica, imply that lineage-specific alterations underpin the evolutionary shift to non-invasive placentation in Marsupials.
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Uterine molecular changes for non-invasive embryonic attachment in the Marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae).
Molecular reproduction and development, 2017Co-Authors: Melanie K Laird, Marilyn B. Renfree, Christopher R Murphy, Bronwyn M Mcallan, Geoff Shaw, Jessica R. Dargan, Lillian Paterson, Michael B ThompsonAbstract:Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and Marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the Marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in Marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localization patterns of Talin, a key basal anchoring molecule, in the uterine epithelium during pregnancy in the tammar wallaby (Macropus eugenii; Macropodidae) and the brush tail possum (Trichosurus vulpecula; Phalangeridae). Embryonic attachment is non-invasive in both species, yet Talin undergoes a clear distributional change during pregnancy in M. eugenii, including recruitment to the base of the uterine epithelium just before attachment, that closely resembles that of invasive implantation in the Marsupial species Sminthopsis crassicaudata. Basal localization occurs throughout pregnancy in T. vulpecula, although, as for M. eugenii, this pattern is most specific prior to attachment. Such molecular reinforcement of the uterine epithelium for non-invasive embryonic attachment in Marsupials supports the hypothesis that less-invasive and non-invasive embryonic attachment in Marsupials may have evolved via accrual of maternal defences. Recruitment of basal molecules, including Talin, to the uterine epithelium may have played a key role in this transition.
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uterine remodelling during pregnancy and pseudopregnancy in the brushtail possum trichosurus vulpecula phalangeridae
Journal of Anatomy, 2017Co-Authors: Melanie K Laird, Hanon Mcshea, Christopher R Murphy, Bronwyn M Mcallan, Michael B ThompsonAbstract:The formation of a placenta is critical for successful mammalian pregnancy and requires remodelling of the uterine epithelium. In eutherian mammals, remodelling involves specific morphological changes that often correlate with the mode of embryonic attachment. Given the differences between Marsupial and eutherian placentae, formation of a Marsupial placenta may involve patterns of uterine remodelling that are different from those in eutherians. Here we present a detailed morphological study of the uterus of the brushtail possum (Trichosurus vulpecula; Phalangeridae) throughout pregnancy, using both scanning and transmission electron microscopy, to identify whether uterine changes in Marsupials correlate with mode of embryonic attachment as they do in eutherian mammals. The uterine remodelling of T. vulpecula is similar to that of eutherian mammals with the same mode of embryonic attachment (non-invasive, epitheliochorial placentation). The morphological similarities include development of large apical projections, and a decrease in the diffusion distance for haemotrophes around the period of embryonic attachment. Importantly, remodelling of the uterus in T. vulpecula during pregnancy differs from that of a Marsupial species with non-invasive attachment (Macropus eugenii; Macropodidae) but is similar to that of a Marsupial with invasive attachment (Monodelphis domestica; Didelphidae). We conclude that modes of embryonic attachment may not be typified by a particular suite of uterine changes in Marsupials, as is the case for eutherian mammals, and that uterine remodelling may instead reflect phylogenetic relationships between Marsupial lineages.
Melanie K Laird - One of the best experts on this subject based on the ideXlab platform.
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uterine epithelial remodelling during pregnancy in the Marsupial monodelphis domestica didelphidae implications for mammalian placental evolution
Journal of Anatomy, 2020Co-Authors: Melanie K Laird, Christopher R Murphy, Bronwyn M Mcallan, Victoria L Hansen, Michael B ThompsonAbstract:Mammalian pregnancy involves remodelling of the uterine epithelium to enable placentation. In Marsupials, such remodelling has probably played a key role in the transition from ancestral invasive placentation to non-invasive placentation. Identifying uterine alterations that are unique to Marsupials with non-invasive placentation can thus elucidate mechanisms of Marsupial placental evolution. We identified apical alterations to uterine epithelial cells prior to implantation in Monodelphis domestica, a member of the least derived living Marsupial clade (Didelphidae) with invasive (endotheliochorial) placentation. We then compared these traits with those of Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae), both with non-invasive placentation, to identify which alterations to the uterine epithelium are ancestral and which facilitate secondarily evolved non-invasive placentation. In M. domestica, remodelling of the uterine epithelium involves reduced cellular heterogeneity and development of uterodome-like cells, suggesting that similar alterations may also have occurred in the Marsupial common ancestor. These alterations also overlap with those of both T. vulpecula and Ma. eugenii, suggesting that the placental shift from invasive to non-invasive placentation in Marsupials involves essential, conserved characteristics, irrespective of placental mode. However, unique apical alterations of both T. vulpecula and Ma. eugenii, relative to M. domestica, imply that lineage-specific alterations underpin the evolutionary shift to non-invasive placentation in Marsupials.
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Uterine molecular changes for non-invasive embryonic attachment in the Marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae).
Molecular reproduction and development, 2017Co-Authors: Melanie K Laird, Marilyn B. Renfree, Christopher R Murphy, Bronwyn M Mcallan, Geoff Shaw, Jessica R. Dargan, Lillian Paterson, Michael B ThompsonAbstract:Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and Marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the Marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in Marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localization patterns of Talin, a key basal anchoring molecule, in the uterine epithelium during pregnancy in the tammar wallaby (Macropus eugenii; Macropodidae) and the brush tail possum (Trichosurus vulpecula; Phalangeridae). Embryonic attachment is non-invasive in both species, yet Talin undergoes a clear distributional change during pregnancy in M. eugenii, including recruitment to the base of the uterine epithelium just before attachment, that closely resembles that of invasive implantation in the Marsupial species Sminthopsis crassicaudata. Basal localization occurs throughout pregnancy in T. vulpecula, although, as for M. eugenii, this pattern is most specific prior to attachment. Such molecular reinforcement of the uterine epithelium for non-invasive embryonic attachment in Marsupials supports the hypothesis that less-invasive and non-invasive embryonic attachment in Marsupials may have evolved via accrual of maternal defences. Recruitment of basal molecules, including Talin, to the uterine epithelium may have played a key role in this transition.
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uterine remodelling during pregnancy and pseudopregnancy in the brushtail possum trichosurus vulpecula phalangeridae
Journal of Anatomy, 2017Co-Authors: Melanie K Laird, Hanon Mcshea, Christopher R Murphy, Bronwyn M Mcallan, Michael B ThompsonAbstract:The formation of a placenta is critical for successful mammalian pregnancy and requires remodelling of the uterine epithelium. In eutherian mammals, remodelling involves specific morphological changes that often correlate with the mode of embryonic attachment. Given the differences between Marsupial and eutherian placentae, formation of a Marsupial placenta may involve patterns of uterine remodelling that are different from those in eutherians. Here we present a detailed morphological study of the uterus of the brushtail possum (Trichosurus vulpecula; Phalangeridae) throughout pregnancy, using both scanning and transmission electron microscopy, to identify whether uterine changes in Marsupials correlate with mode of embryonic attachment as they do in eutherian mammals. The uterine remodelling of T. vulpecula is similar to that of eutherian mammals with the same mode of embryonic attachment (non-invasive, epitheliochorial placentation). The morphological similarities include development of large apical projections, and a decrease in the diffusion distance for haemotrophes around the period of embryonic attachment. Importantly, remodelling of the uterus in T. vulpecula during pregnancy differs from that of a Marsupial species with non-invasive attachment (Macropus eugenii; Macropodidae) but is similar to that of a Marsupial with invasive attachment (Monodelphis domestica; Didelphidae). We conclude that modes of embryonic attachment may not be typified by a particular suite of uterine changes in Marsupials, as is the case for eutherian mammals, and that uterine remodelling may instead reflect phylogenetic relationships between Marsupial lineages.
Marilyn B. Renfree - One of the best experts on this subject based on the ideXlab platform.
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Uterine molecular changes for non-invasive embryonic attachment in the Marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae).
Molecular reproduction and development, 2017Co-Authors: Melanie K Laird, Marilyn B. Renfree, Christopher R Murphy, Bronwyn M Mcallan, Geoff Shaw, Jessica R. Dargan, Lillian Paterson, Michael B ThompsonAbstract:Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and Marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the Marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in Marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localization patterns of Talin, a key basal anchoring molecule, in the uterine epithelium during pregnancy in the tammar wallaby (Macropus eugenii; Macropodidae) and the brush tail possum (Trichosurus vulpecula; Phalangeridae). Embryonic attachment is non-invasive in both species, yet Talin undergoes a clear distributional change during pregnancy in M. eugenii, including recruitment to the base of the uterine epithelium just before attachment, that closely resembles that of invasive implantation in the Marsupial species Sminthopsis crassicaudata. Basal localization occurs throughout pregnancy in T. vulpecula, although, as for M. eugenii, this pattern is most specific prior to attachment. Such molecular reinforcement of the uterine epithelium for non-invasive embryonic attachment in Marsupials supports the hypothesis that less-invasive and non-invasive embryonic attachment in Marsupials may have evolved via accrual of maternal defences. Recruitment of basal molecules, including Talin, to the uterine epithelium may have played a key role in this transition.
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2016Co-Authors: Ryuichi Ono, Takanori Narita, Andrew J Pask, Changshan Wang, Amber E Alsop, Jennifer Marshall A Graves, Geoffrey Shaw, Yuji Kohara, Takashi Kohda, Marilyn B. RenfreeAbstract:Among mammals, only eutherians and Marsupials are viviparous and have genomic imprinting that leads to parent-of-origin-specific differential gene expression. We used comparative analysis to investigate the origin of genomic imprinting in mammals. PEG10 (paternally expressed 10) is a retrotransposon-derived imprinted gene that has an essential role for the formation of the placenta of the mouse. Here, we show that an orthologue of PEG10 exists in another therian mammal, the Marsupial tammar wallaby (Macropus eugenii), but not in a prototherian mammal, the egg-laying platypus (Ornithorhynchus anatinus), suggesting its close relationship to the origin of placentation in therian mammals. We have discovered a hitherto missing link of the imprinting mechanism between eutherians and Marsupials because tammar PEG10 is the first example of a differentially methylated region (DMR) associated with genomic imprinting in Marsupials. Surprisingly, the Marsupial DMR was strictly limited to the 59 region of PEG10, unlike the eutherian DMR, which covers the promoter regions of both PEG10 and the adjacent imprinted gene SGCE. These results not only demonstrate a common origin of the DMR-associated imprinting mechanism in therian mammals but provide the first demonstration that DMR-associated genomic imprinting in eutherians can originat
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postnatal epigenetic reprogramming in the germline of a Marsupial the tammar wallaby
Epigenetics & Chromatin, 2013Co-Authors: Geoffrey Shaw, Shunsuke Suzuki, Marilyn B. RenfreeAbstract:Background Epigenetic reprogramming is essential to restore totipotency and to reset genomic imprints during mammalian germ cell development and gamete formation. The dynamic DNA methylation change at DMRs (differentially methylated regions) within imprinted domains and of retrotransposons is characteristic of this process. Both Marsupials and eutherian mammals have genomic imprinting but these two subgroups have been evolving separately for up to 160 million years. Marsupials have a unique reproductive strategy and deliver tiny, altricial young that complete their development within their mother's pouch. Germ cell proliferation in the genital ridge continues after birth in the tammar wallaby (Macropus eugenii), and it is only after 25 days postpartum that female germ cells begin to enter meiosis and male germ cells begin to enter mitotic arrest. At least two Marsupial imprinted loci (PEG10 and H19) also have DMRs. To investigate the evolution of epigenetic reprogramming in the Marsupial germline, here we collected germ cells from male pouch young of the tammar wallaby and analysed the methylation status of PEG10 and H19 DMR, an LTR (long terminal repeat) and a non-LTR retrotransposons.
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placental expression of pituitary hormones is an ancestral feature of therian mammals
Evodevo, 2011Co-Authors: Brandon R Menzies, Andrew J Pask, Marilyn B. RenfreeAbstract:Background: The placenta is essential for supplying nutrients and gases to the developing mammalian young before birth. While all mammals have a functional placenta, only in therian mammals (Marsupials and eutherians) does the placenta closely appose or invade the uterine endometrium. The eutherian placenta secretes hormones that are structurally and functionally similar to pituitary growth hormone (GH), prolactin (PRL) and luteinizing hormone (LH). Marsupial and eutherian mammals diverged from a common ancestor approximately 125 to 148 million years ago and developed distinct reproductive strategies. As in eutherians, Marsupials rely on a short-lived but functional placenta for embryogenesis. Results: We characterized pituitary GH, GH-R, IGF-2, PRL and LHb in a macropodid Marsupial, the tammar wallaby, Macropus eugenii. These genes were expressed in the tammar placenta during the last third of gestation when most fetal growth occurs and active organogenesis is initiated. The mRNA of key growth genes GH, GH-R, IGF-2 and PRL were expressed during late pregnancy. We found significant up-regulation of GH, GH-R and IGF-2 after the start of the rapid growth phase of organogenesis which suggests that the placental growth hormones regulate the rapid phase of fetal growth. Conclusions: This is the first demonstration of the existence of pituitary hormones in the Marsupial placenta. Placental expression of these pituitary hormones has clearly been conserved in Marsupials as in eutherian mammals, suggesting an ancestral origin of the evolution of placental expression and a critical function of these hormones in growth and development of all therian mammals.
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review Marsupials placental mammals with a difference
Placenta, 2010Co-Authors: Marilyn B. RenfreeAbstract:The placenta is the most varied organ within the Mammalia. There are many similarities, as well as some differences, between the Marsupial embryo and those of eutherian mammals. The most striking difference is the lack of the inner cell mass in the blastocyst which consists solely of a single layer of trophoblast cells. The trophoblast expands and eventually becomes part of the definitive chorio-vitelline placenta. The degree of functional differentiation between the vascular and non-vascular parts of the yolk sac placenta differs between species in the relative surface area that is attached to the endometrium, in trophoblast thickness, in yolk sac fusion with the luminal epithelium and most markedly in the degree of invasiveness. In Marsupials, placental physiology has been best studied in the tammar wallaby. Despite the lack of invasion in the tammar, there is nevertheless maternal recognition of pregnancy in response to trophoblast formation. Contrary to popular opinion, the tammar placenta also elaborates hormones: at term it secretes prostaglandin F2α and accumulates cortisol, and it expresses genes for hormones such as growth hormone, IGF2 and relaxin. As in eutherian mammals, genomic imprinting is important for placental function. Despite the relatively short period of placentation, it is clear that the trophoblast and the placenta it forms are as important for successful pregnancy in Marsupial as in eutherian mammals. Marsupials are certainly placental mammals. However Marsupials have an additional trick in their pouches, with the physiologically sophisticated and extended lactation that has allowed them to exchange the umbilical cord for the teat.
Jennifer Marshall A Graves - One of the best experts on this subject based on the ideXlab platform.
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2
2016Co-Authors: Ryuichi Ono, Takanori Narita, Andrew J Pask, Changshan Wang, Amber E Alsop, Jennifer Marshall A Graves, Geoffrey Shaw, Yuji Kohara, Takashi Kohda, Marilyn B. RenfreeAbstract:Among mammals, only eutherians and Marsupials are viviparous and have genomic imprinting that leads to parent-of-origin-specific differential gene expression. We used comparative analysis to investigate the origin of genomic imprinting in mammals. PEG10 (paternally expressed 10) is a retrotransposon-derived imprinted gene that has an essential role for the formation of the placenta of the mouse. Here, we show that an orthologue of PEG10 exists in another therian mammal, the Marsupial tammar wallaby (Macropus eugenii), but not in a prototherian mammal, the egg-laying platypus (Ornithorhynchus anatinus), suggesting its close relationship to the origin of placentation in therian mammals. We have discovered a hitherto missing link of the imprinting mechanism between eutherians and Marsupials because tammar PEG10 is the first example of a differentially methylated region (DMR) associated with genomic imprinting in Marsupials. Surprisingly, the Marsupial DMR was strictly limited to the 59 region of PEG10, unlike the eutherian DMR, which covers the promoter regions of both PEG10 and the adjacent imprinted gene SGCE. These results not only demonstrate a common origin of the DMR-associated imprinting mechanism in therian mammals but provide the first demonstration that DMR-associated genomic imprinting in eutherians can originat
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evolution of genomic imprinting insights from Marsupials and monotremes
Annual Review of Genomics and Human Genetics, 2009Co-Authors: Marilyn B. Renfree, Geoffrey Shaw, Jennifer Marshall A Graves, Timothy A. Hore, Andrew J PaskAbstract:Parent-of-origin gene expression (genomic imprinting) is widespread among eutherian mammals and also occurs in Marsupials. Most imprinted genes are expressed in the placenta, but the brain is also a favored site. Although imprinting evolved in therian mammals before the Marsupial-eutherian split, the mechanisms have continued to evolve in each lineage to produce differences between the two groups in terms of the number and regulation of imprinted genes. As yet there is no evidence for genomic imprinting in the egg-laying monotreme mammals, although these mammals also form a placenta (albeit short-lived) and transfer nutrients from mother to embryo. Therefore, imprinting was not essential for the evolution of the placenta and its importance in nutrient transfer but the elaboration of imprinted genes in Marsupials and eutherians is associated with viviparity. Here we review the recent analyses of imprinted gene clusters in Marsupials and monotremes, which have served to shed light on the origin and evolutio...
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evolution of genomic imprinting insights from Marsupials and monotremes
Annual Review of Genomics and Human Genetics, 2009Co-Authors: Marilyn B. Renfree, Geoffrey Shaw, Jennifer Marshall A Graves, Timothy A. Hore, Andrew J PaskAbstract:Parent-of-origin gene expression (genomic imprinting) is widespread among eutherian mammals and also occurs in Marsupials. Most imprinted genes are expressed in the placenta, but the brain is also a favored site. Although imprinting evolved in therian mammals before the Marsupial-eutherian split, the mechanisms have continued to evolve in each lineage to produce differences between the two groups in terms of the number and regulation of imprinted genes. As yet there is no evidence for genomic imprinting in the egg-laying monotreme mammals, although these mammals also form a placenta (albeit short-lived) and transfer nutrients from mother to embryo. Therefore, imprinting was not essential for the evolution of the placenta and its importance in nutrient transfer but the elaboration of imprinted genes in Marsupials and eutherians is associated with viviparity. Here we review the recent analyses of imprinted gene clusters in Marsupials and monotremes, which have served to shed light on the origin and evolution of imprinting mechanisms in mammals.
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retrotransposon silencing by dna methylation can drive mammalian genomic imprinting
PLOS Genetics, 2007Co-Authors: Shunsuke Suzuki, Takanori Narita, Andrew J Pask, Changshan Wang, Amber E Alsop, Jennifer Marshall A Graves, Geoffrey Shaw, Yuji Kohara, Takashi Kohda, Fumitoshi IshinoAbstract:Among mammals, only eutherians and Marsupials are viviparous and have genomic imprinting that leads to parent-of-origin-specific differential gene expression. We used comparative analysis to investigate the origin of genomic imprinting in mammals. PEG10 (paternally expressed 10) is a retrotransposon-derived imprinted gene that has an essential role for the formation of the placenta of the mouse. Here, we show that an orthologue of PEG10 exists in another therian mammal, the Marsupial tammar wallaby (Macropus eugenii), but not in a prototherian mammal, the egg-laying platypus (Ornithorhynchus anatinus), suggesting its close relationship to the origin of placentation in therian mammals. We have discovered a hitherto missing link of the imprinting mechanism between eutherians and Marsupials because tammar PEG10 is the first example of a differentially methylated region (DMR) associated with genomic imprinting in Marsupials. Surprisingly, the Marsupial DMR was strictly limited to the 5′ region of PEG10, unlike the eutherian DMR, which covers the promoter regions of both PEG10 and the adjacent imprinted gene SGCE. These results not only demonstrate a common origin of the DMR-associated imprinting mechanism in therian mammals but provide the first demonstration that DMR-associated genomic imprinting in eutherians can originate from the repression of exogenous DNA sequences and/or retrotransposons by DNA methylation.
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retrotransposon silencing by dna methylation can drive mammalian genomic imprinting
PLOS Genetics, 2007Co-Authors: Shunsuke Suzuki, Takanori Narita, Andrew J Pask, Changshan Wang, Amber E Alsop, Jennifer Marshall A Graves, Geoffrey Shaw, Yuji Kohara, Takashi Kohda, Fumitoshi IshinoAbstract:Among mammals, only eutherians and Marsupials are viviparous and have genomic imprinting that leads to parent-of-origin-specific differential gene expression. We used comparative analysis to investigate the origin of genomic imprinting in mammals. PEG10 (paternally expressed 10) is a retrotransposon-derived imprinted gene that has an essential role for the formation of the placenta of the mouse. Here, we show that an orthologue of PEG10 exists in another therian mammal, the Marsupial tammar wallaby (Macropus eugenii), but not in a prototherian mammal, the egg-laying platypus (Ornithorhynchus anatinus), suggesting its close relationship to the origin of placentation in therian mammals. We have discovered a hitherto missing link of the imprinting mechanism between eutherians and Marsupials because tammar PEG10 is the first example of a differentially methylated region (DMR) associated with genomic imprinting in Marsupials. Surprisingly, the Marsupial DMR was strictly limited to the 5′ region of PEG10, unlike the eutherian DMR, which covers the promoter regions of both PEG10 and the adjacent imprinted gene SGCE. These results not only demonstrate a common origin of the DMR-associated imprinting mechanism in therian mammals but provide the first demonstration that DMR-associated genomic imprinting in eutherians can originate from the repression of exogenous DNA sequences and/or retrotransposons by DNA methylation.
Christopher R Murphy - One of the best experts on this subject based on the ideXlab platform.
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uterine epithelial remodelling during pregnancy in the Marsupial monodelphis domestica didelphidae implications for mammalian placental evolution
Journal of Anatomy, 2020Co-Authors: Melanie K Laird, Christopher R Murphy, Bronwyn M Mcallan, Victoria L Hansen, Michael B ThompsonAbstract:Mammalian pregnancy involves remodelling of the uterine epithelium to enable placentation. In Marsupials, such remodelling has probably played a key role in the transition from ancestral invasive placentation to non-invasive placentation. Identifying uterine alterations that are unique to Marsupials with non-invasive placentation can thus elucidate mechanisms of Marsupial placental evolution. We identified apical alterations to uterine epithelial cells prior to implantation in Monodelphis domestica, a member of the least derived living Marsupial clade (Didelphidae) with invasive (endotheliochorial) placentation. We then compared these traits with those of Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae), both with non-invasive placentation, to identify which alterations to the uterine epithelium are ancestral and which facilitate secondarily evolved non-invasive placentation. In M. domestica, remodelling of the uterine epithelium involves reduced cellular heterogeneity and development of uterodome-like cells, suggesting that similar alterations may also have occurred in the Marsupial common ancestor. These alterations also overlap with those of both T. vulpecula and Ma. eugenii, suggesting that the placental shift from invasive to non-invasive placentation in Marsupials involves essential, conserved characteristics, irrespective of placental mode. However, unique apical alterations of both T. vulpecula and Ma. eugenii, relative to M. domestica, imply that lineage-specific alterations underpin the evolutionary shift to non-invasive placentation in Marsupials.
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Uterine molecular changes for non-invasive embryonic attachment in the Marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae).
Molecular reproduction and development, 2017Co-Authors: Melanie K Laird, Marilyn B. Renfree, Christopher R Murphy, Bronwyn M Mcallan, Geoff Shaw, Jessica R. Dargan, Lillian Paterson, Michael B ThompsonAbstract:Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and Marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the Marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in Marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localization patterns of Talin, a key basal anchoring molecule, in the uterine epithelium during pregnancy in the tammar wallaby (Macropus eugenii; Macropodidae) and the brush tail possum (Trichosurus vulpecula; Phalangeridae). Embryonic attachment is non-invasive in both species, yet Talin undergoes a clear distributional change during pregnancy in M. eugenii, including recruitment to the base of the uterine epithelium just before attachment, that closely resembles that of invasive implantation in the Marsupial species Sminthopsis crassicaudata. Basal localization occurs throughout pregnancy in T. vulpecula, although, as for M. eugenii, this pattern is most specific prior to attachment. Such molecular reinforcement of the uterine epithelium for non-invasive embryonic attachment in Marsupials supports the hypothesis that less-invasive and non-invasive embryonic attachment in Marsupials may have evolved via accrual of maternal defences. Recruitment of basal molecules, including Talin, to the uterine epithelium may have played a key role in this transition.
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uterine remodelling during pregnancy and pseudopregnancy in the brushtail possum trichosurus vulpecula phalangeridae
Journal of Anatomy, 2017Co-Authors: Melanie K Laird, Hanon Mcshea, Christopher R Murphy, Bronwyn M Mcallan, Michael B ThompsonAbstract:The formation of a placenta is critical for successful mammalian pregnancy and requires remodelling of the uterine epithelium. In eutherian mammals, remodelling involves specific morphological changes that often correlate with the mode of embryonic attachment. Given the differences between Marsupial and eutherian placentae, formation of a Marsupial placenta may involve patterns of uterine remodelling that are different from those in eutherians. Here we present a detailed morphological study of the uterus of the brushtail possum (Trichosurus vulpecula; Phalangeridae) throughout pregnancy, using both scanning and transmission electron microscopy, to identify whether uterine changes in Marsupials correlate with mode of embryonic attachment as they do in eutherian mammals. The uterine remodelling of T. vulpecula is similar to that of eutherian mammals with the same mode of embryonic attachment (non-invasive, epitheliochorial placentation). The morphological similarities include development of large apical projections, and a decrease in the diffusion distance for haemotrophes around the period of embryonic attachment. Importantly, remodelling of the uterus in T. vulpecula during pregnancy differs from that of a Marsupial species with non-invasive attachment (Macropus eugenii; Macropodidae) but is similar to that of a Marsupial with invasive attachment (Monodelphis domestica; Didelphidae). We conclude that modes of embryonic attachment may not be typified by a particular suite of uterine changes in Marsupials, as is the case for eutherian mammals, and that uterine remodelling may instead reflect phylogenetic relationships between Marsupial lineages.
