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Worapong Singchat - One of the best experts on this subject based on the ideXlab platform.
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Do sex chromosomes of snakes, monitor lizards, and iguanian lizards result from multiple fission of an “ancestral Amniote super-sex chromosome”?
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Rebecca E. O’connor, Darren K. Griffin, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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do sex chromosomes of snakes monitor lizards and iguanian lizards result from multiple fission of an ancestral Amniote super sex chromosome
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Darren K. Griffin, Rebecca E Oconnor, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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Chromosome map of the Siamese cobra: did partial synteny of sex chromosomes in the Amniote represent “a hypothetical ancestral super-sex chromosome” or random distribution?
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E. O’connor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Background Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra ( Naja kaouthia ) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. Results We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)_n and six microsatellite repeat motifs ((AAGG)_8, (AGAT)_8, (AAAC)_8, (ACAG)_8, (AATC)_8, and (AAAAT)_6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. Conclusions The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.
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chromosome map of the siamese cobra did partial synteny of sex chromosomes in the Amniote represent a hypothetical ancestral super sex chromosome or random distribution
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E Oconnor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra (Naja kaouthia) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)n and six microsatellite repeat motifs ((AAGG)8, (AGAT)8, (AAAC)8, (ACAG)8, (AATC)8, and (AAAAT)6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.
Kornsorn Srikulnath - One of the best experts on this subject based on the ideXlab platform.
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Do sex chromosomes of snakes, monitor lizards, and iguanian lizards result from multiple fission of an “ancestral Amniote super-sex chromosome”?
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Rebecca E. O’connor, Darren K. Griffin, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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do sex chromosomes of snakes monitor lizards and iguanian lizards result from multiple fission of an ancestral Amniote super sex chromosome
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Darren K. Griffin, Rebecca E Oconnor, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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origin of Amniote sex chromosomes an ancestral super sex chromosome or common requirements
Journal of Heredity, 2017Co-Authors: Tariq Ezaz, Kornsorn Srikulnath, Jennifer Marshall A GravesAbstract:The diversity of sex chromosomes among Amniotes is the product of independent evolution of different systems in different lineages, defined by novel sex-determining genes. Convergent evolution is very common, suggesting that some genes are particularly adept at taking on a sex-determining role. Comparative gene mapping, and more recently whole genome sequencing, have now turned up other surprising relationships; different regions of the Amniote genome that have become sex determining in some taxa seem to share synteny, or share sequence, in others. Is this, after all, evidence that these regions were once linked in a super-sex chromosome that underwent multiple fission in different ways in different Amniote lineages? Or does it signify that special properties of sex chromosomes (paucity of active genes, low recombination, epigenetic regulation to achieve dosage compensation) predispose particular chromosomes to a sex-determining role?
David P Polly - One of the best experts on this subject based on the ideXlab platform.
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evolution of the snake body form reveals homoplasy in Amniote hox gene function
Nature, 2015Co-Authors: Jason J. Head, David P PollyAbstract:Traditionally, the vertebral column of snakes was thought to have lost regionalization; Hox regionalization is now shown to be maintained in snakes, suggesting that gradational vertebral column regionalization is primitive to Amniotes. It had been thought that the vertebral column of snakes has lost regionalization anterior to the cloaca, either because of homogenization of body-patterning Hox gene codes or of their downstream effectors. Jason Head and David Polly turn received wisdom on its head, with a quantitative analysis of the vertebral column in snakes that shows not only is Hox regionalization maintained, but the morphology is too. This surprising finding suggests that regionalization is primitive to Amniotes, even though that regionalization might be quite subtle. In which case, the more apparent regionalization in some archosaurs (crocodiles and birds) and in mammals could be a consequence of independent evolution in the Hox code, rather than representing the ancestral condition for clades with snake-like body forms. Hox genes regulate regionalization of the axial skeleton in vertebrates1,2,3,4,5,6,7, and changes in their expression have been proposed to be a fundamental mechanism driving the evolution of new body forms8,9,10,11,12,13,14. The origin of the snake-like body form, with its deregionalized pre-cloacal axial skeleton, has been explained as either homogenization of Hox gene expression domains9, or retention of standard vertebrate Hox domains with alteration of downstream expression that suppresses development of distinct regions10,11,12,13. Both models assume a highly regionalized ancestor, but the extent of deregionalization of the primaxial domain (vertebrae, dorsal ribs) of the skeleton in snake-like body forms has never been analysed. Here we combine geometric morphometrics and maximum-likelihood analysis to show that the pre-cloacal primaxial domain of elongate, limb-reduced lizards and snakes is not deregionalized compared with limbed taxa, and that the phylogenetic structure of primaxial morphology in reptiles does not support a loss of regionalization in the evolution of snakes. We demonstrate that morphometric regional boundaries correspond to mapped gene expression domains in snakes, suggesting that their primaxial domain is patterned by a normally functional Hox code. Comparison of primaxial osteology in fossil and modern Amniotes with Hox gene distributions within Amniota indicates that a functional, sequentially expressed Hox code patterned a subtle morphological gradient along the anterior–posterior axis in stem members of Amniote clades and extant lizards, including snakes. The highly regionalized skeletons of extant archosaurs and mammals result from independent evolution in the Hox code and do not represent ancestral conditions for clades with snake-like body forms. The developmental origin of snakes is best explained by decoupling of the primaxial and abaxial domains and by increases in somite number15, not by changes in the function of primaxial Hox genes9,10.
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evolution of the snake body form reveals homoplasy in Amniote hox gene function
Nature, 2015Co-Authors: Jason J. Head, David P PollyAbstract:Hox genes regulate regionalization of the axial skeleton in vertebrates, and changes in their expression have been proposed to be a fundamental mechanism driving the evolution of new body forms. The origin of the snake-like body form, with its deregionalized pre-cloacal axial skeleton, has been explained as either homogenization of Hox gene expression domains, or retention of standard vertebrate Hox domains with alteration of downstream expression that suppresses development of distinct regions. Both models assume a highly regionalized ancestor, but the extent of deregionalization of the primaxial domain (vertebrae, dorsal ribs) of the skeleton in snake-like body forms has never been analysed. Here we combine geometric morphometrics and maximum-likelihood analysis to show that the pre-cloacal primaxial domain of elongate, limb-reduced lizards and snakes is not deregionalized compared with limbed taxa, and that the phylogenetic structure of primaxial morphology in reptiles does not support a loss of regionalization in the evolution of snakes. We demonstrate that morphometric regional boundaries correspond to mapped gene expression domains in snakes, suggesting that their primaxial domain is patterned by a normally functional Hox code. Comparison of primaxial osteology in fossil and modern Amniotes with Hox gene distributions within Amniota indicates that a functional, sequentially expressed Hox code patterned a subtle morphological gradient along the anterior-posterior axis in stem members of Amniote clades and extant lizards, including snakes. The highly regionalized skeletons of extant archosaurs and mammals result from independent evolution in the Hox code and do not represent ancestral conditions for clades with snake-like body forms. The developmental origin of snakes is best explained by decoupling of the primaxial and abaxial domains and by increases in somite number, not by changes in the function of primaxial Hox genes.
Surin Peyachoknagul - One of the best experts on this subject based on the ideXlab platform.
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Do sex chromosomes of snakes, monitor lizards, and iguanian lizards result from multiple fission of an “ancestral Amniote super-sex chromosome”?
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Rebecca E. O’connor, Darren K. Griffin, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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do sex chromosomes of snakes monitor lizards and iguanian lizards result from multiple fission of an ancestral Amniote super sex chromosome
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Darren K. Griffin, Rebecca E Oconnor, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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Chromosome map of the Siamese cobra: did partial synteny of sex chromosomes in the Amniote represent “a hypothetical ancestral super-sex chromosome” or random distribution?
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E. O’connor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Background Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra ( Naja kaouthia ) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. Results We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)_n and six microsatellite repeat motifs ((AAGG)_8, (AGAT)_8, (AAAC)_8, (ACAG)_8, (AATC)_8, and (AAAAT)_6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. Conclusions The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.
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chromosome map of the siamese cobra did partial synteny of sex chromosomes in the Amniote represent a hypothetical ancestral super sex chromosome or random distribution
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E Oconnor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra (Naja kaouthia) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)n and six microsatellite repeat motifs ((AAGG)8, (AGAT)8, (AAAC)8, (ACAG)8, (AATC)8, and (AAAAT)6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.
Narongrit Muangmai - One of the best experts on this subject based on the ideXlab platform.
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Do sex chromosomes of snakes, monitor lizards, and iguanian lizards result from multiple fission of an “ancestral Amniote super-sex chromosome”?
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Rebecca E. O’connor, Darren K. Griffin, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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do sex chromosomes of snakes monitor lizards and iguanian lizards result from multiple fission of an ancestral Amniote super sex chromosome
Chromosome Research, 2020Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Chantra Indananda, Prateep Duengkae, Surin Peyachoknagul, Darren K. Griffin, Rebecca E Oconnor, Kornsorn SrikulnathAbstract:Sex chromosomes in some Amniotes share linkage homologies with distantly related taxa in regions orthologous to squamate reptile chromosome 2 (SR2) and the snake W sex chromosome. Thus, the SR2 and W chromosomes may formerly have been part of a larger ancestral Amniote super-sex chromosome. Comparison of various sex chromosomal linkage homologies in Toxicofera with those in other Amniotes offers an excellent model to assess key cytological differences, to understand the mechanisms of Amniote sex chromosome evolution in each lineage and the existence of an ancestral Amniote super-sex chromosome. Chromosome maps of four species of Toxicofera were constructed using bacterial artificial chromosomes (BACs) derived from chicken and zebra finch libraries containing Amniote sex chromosomal linkages. Different macrochromosome linkage homologies were highly conserved among Toxicofera, and at least two BACs (CH261-125F1 and CH261-40D6) showed partial homology with sex chromosomes of Amniotes associated with SR2, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial linkage homologies. The present data also suggest a possible multiple fission mechanism of an ancestral super-sex chromosome, which resulted in further development of various sex chromosomal linkages of Toxicofera based on particular properties that favored the role of sex chromosomes.
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Chromosome map of the Siamese cobra: did partial synteny of sex chromosomes in the Amniote represent “a hypothetical ancestral super-sex chromosome” or random distribution?
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E. O’connor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Background Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra ( Naja kaouthia ) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. Results We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)_n and six microsatellite repeat motifs ((AAGG)_8, (AGAT)_8, (AAAC)_8, (ACAG)_8, (AATC)_8, and (AAAAT)_6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. Conclusions The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.
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chromosome map of the siamese cobra did partial synteny of sex chromosomes in the Amniote represent a hypothetical ancestral super sex chromosome or random distribution
BMC Genomics, 2018Co-Authors: Worapong Singchat, Siwapech Sillapaprayoon, Narongrit Muangmai, Sudarath Baicharoen, Surin Peyachoknagul, Rebecca E Oconnor, Panupong Tawichasri, Aorarat Suntronpong, Sunutcha Suntrarachun, Lawan ChanhomeAbstract:Unlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other Amniotes, we constructed a chromosome map of the Siamese cobra (Naja kaouthia) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other Amniotes. We produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several Amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)n and six microsatellite repeat motifs ((AAGG)8, (AGAT)8, (AAAC)8, (ACAG)8, (AATC)8, and (AAAAT)6) were observed on NKAW, and most of these were also found on other Amniote sex chromosomes. The frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among Amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among Amniote sex chromosomes.