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Tariq Ezaz - One of the best experts on this subject based on the ideXlab platform.
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distribution and amplification of interstitial telomeric sequences itss in australian dragon lizards support frequent chromosome fusions in iguania
PLOS ONE, 2019Co-Authors: Kornsorn Srikulnath, Bhumika Azad, Worapong Singchat, Tariq EzazAbstract:: Telomeric sequences are generally located at the ends of chromosomes; however, they can also be found in non-terminal chromosomal regions when they are known as interstitial telomeric sequences (ITSs). Distribution of ITSs across closely related and divergent species elucidates karyotype evolution and speciation as ITSs provide evolutionary evidence for chromosome fusion. In this study, we performed physical mapping of telomeric repeats by fluorescence in situ hybridisation (FISH) in seven Australian dragon lizards thought to represent derived karyotypes of squamate reptiles and a gecko lizard with considerably different karyotypic feature. Telomeric repeats were present at both ends of all chromosomes in all species, while varying numbers of ITSs were also found on Microchromosomes and in pericentromeric or centromeric regions on macrochromosomes in five lizard species examined. This suggests that chromosomal rearrangements from ancestral squamate reptiles to Iguania occurred mainly by fusion between ancestral types of acrocentric chromosomes and/or between Microchromosomes, leading to appearance of bi-armed macrochromosomes, and in the reduction of Microchromosome numbers. These results support the previously proposed hypothesis of karyotype evolution in squamate reptiles. In addition, we observed the presence of telomeric sequences in the similar regions to heterochromatin of the W Microchromosome in Pogona barbata and Doporiphora nobbi, while sex chromosomes for the two species contained part of the nucleolar organiser regions (NORs). This likely implies that these ITSs are a part of the satellite DNA and not relics of chromosome fusions. Amplification of telomeric repeats may have involved heterochromatinisation of sex-specific W chromosomes and play a role in the organisation of the nucleolus.
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Chromosome painting with V. acanthurus Microchromosome probes.
2014Co-Authors: Kazumi Matsubara, Arthur Georges, Yoichi Matsuda, Stephen D. Sarre, Jennifer Marshall A. Graves, Tariq EzazAbstract:Painting with the W chromosome probe in female V. acanthurus (a), the large Microchromosome probe in female V. acanthurus (b), an autosomal Microchromosome probe in male (c) and female V. acanthurus (d), and the W chromosome probe in female V. rosenbergi (e) and V. gouldii (f). Arrowheads indicate hybridization signals. ‘W’, ‘Lm’ and ‘m’ indicate W chromosomes in the three species (a, b, d–f), large Microchromosomes in male and female V. acanthurus (a–d), and Microchromosome to which the probe has been hybridized in male and female V. acanthurus (c, d), respectively. Scale bars indicate 10 µm.
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Sequence and gene content of a large fragment of a lizard sex chromosome and evaluation of candidate sex differentiating gene R-spondin 1
BMC Genomics, 2013Co-Authors: Tariq Ezaz, Kazumi Matsubara, Bhumika Azad, Denis O’meally, Matthew J. Young, Melanie J. Edwards, Xiuwen Zhang, Clare E. Holleley, Janine E. Deakin, Jennifer A. Marshall GravesAbstract:Background: Scant genomic information from non-avian reptile sex chromosomes is available, and for only a few lizards, several snakes and one turtle species, and it represents only a small fraction of the total sex chromosome sequences in these species. Results: We report a 352 kb of contiguous sequence from the sex chromosome of a squamate reptile, Pogona vitticeps, with a ZZ/ZW sex Microchromosome system. This contig contains five protein coding genes (oprd1, rcc1, znf91, znf131, znf180), and major families of repetitive sequences with a high number of copies of LTR and non-LTR retrotransposons, including the CR1 and Bov-B LINEs. The two genes, oprd1 and rcc1 are part of a homologous syntenic block, which is conserved among amniotes. While oprd1 and rcc1 have no known function in sex determination or differentiation in amniotes, this homologous syntenic block in mammals and chicken also contains R-spondin 1 (rspo1), the ovarian differentiating gene in mammals. In order to explore the probability that rspo1 is sex determining in dragon lizards, genomic BAC and cDNA clones were mapped using fluorescence in situ hybridisation. Their location on an autosomal Microchromosome pair, not on the ZW sex Microchromosomes, eliminates rspo1 as a candidate sex determining gene in P. vitticeps. Conclusion: Our study has characterized the largest contiguous stretch of physically mapped sex chromosome sequence (352 kb) from a ZZ/ZW lizard species. Although this region represents only a small fraction of the sex chromosomes of P. vitticeps, it has revealed several features typically associated with sex chromosomes including the accumulation of large blocks of repetitive sequences.
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Molecular cytogenetic map of the central bearded dragon, Pogona vitticeps (Squamata: Agamidae)
Chromosome Research, 2013Co-Authors: M. J. Young, D. O’meally, S. D. Sarre, A. Georges, Tariq EzazAbstract:Reptiles, as the sister group to birds and mammals, are particularly valuable for comparative genomic studies among amniotes. The Australian central bearded dragon ( Pogona vitticeps ) is being developed as a reptilian model for such comparisons, with whole-genome sequencing near completion. The karyotype consists of 6 pairs of macrochromosomes and 10 pairs Microchromosomes (2 n = 32), including a female heterogametic ZW sex Microchromosome pair. Here, we present a molecular cytogenetic map for P . vitticeps comprising 87 anchor bacterial artificial chromosome clones that together span each macro- and Microchromosome. It is the first comprehensive cytogenetic map for any non-avian reptile. We identified an active nucleolus organizer region (NOR) on the sub-telomeric region of 2q by mapping 18S rDNA and Ag-NOR staining. We identified interstitial telomeric sequences in two Microchromosome pairs and the W chromosome, indicating that Microchromosome fusion has been a mechanism of karyotypic evolution in Australian agamids within the last 21 to 19 million years. Orthology searches against the chicken genome revealed an intrachromosomal rearrangement of P . vitticeps 1q, identified regions orthologous to chicken Z on P . vitticeps 2q, snake Z on P . vitticeps 6q and the autosomal Microchromosome pair in P . vitticeps orthologous to turtle Pelodiscus sinensis ZW and lizard Anolis carolinensis XY. This cytogenetic map will be a valuable reference tool for future gene mapping studies and will provide the framework for the work currently underway to physically anchor genome sequences to chromosomes for this model Australian squamate.
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Extension, single-locus conversion and physical mapping of sex chromosome sequences identify the Z Microchromosome and pseudo-autosomal region in a dragon lizard, Pogona vitticeps
Heredity, 2009Co-Authors: Alexander E. Quinn, Tariq Ezaz, Stephen D. Sarre, J.a. Marshall Graves, Arthur GeorgesAbstract:Distribution of temperature-dependent sex determination (TSD) and genotypic sex determination (GSD) across the phylogeny of dragon lizards implies multiple independent origins of at least one, and probably both, modes of sex determination. Female Pogona vitticeps are the heterogametic sex, but ZZ individuals reverse to a female phenotype at high incubation temperatures. We used reiterated genome walking to extend Z and W chromosome-linked amplified fragment length polymorphism (AFLP) markers, and fluorescence in situ hybridization for physical mapping. One extended fragment hybridized to both W and Z Microchromosomes, identifying the Z Microchromosome for the first time, and a second hybridized to the centromere of all Microchromosomes. W-linked sequences were converted to a single-locus PCR sexing assay. P. vitticeps sex chromosome sequences also shared homology with several other Australian dragons. Further physical mapping and isolation of sex-specific bacterial artificial chromosome clones will provide insight into the evolution of sex determination and sex chromosomes in GSD and TSD dragon lizards.
Jennifer A. Marshall-graves - One of the best experts on this subject based on the ideXlab platform.
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An XX/XY heteromorphic sex chromosome system in the Australian chelid turtle Emydura macquarii: A new piece in the puzzle of sex chromosome evolution in turtles
Chromosome Research, 2008Co-Authors: Pedro Alonzo Martinez, Nicole Valenzuela, Tariq Ezaz, Arthur Georges, Jennifer A. Marshall-gravesAbstract:Chromosomal sex determination is the prevalent system found in animals but is rare among turtles. In fact, heteromorphic sex chromosomes are known in only seven of the turtles possessing genotypic sex determination (GSD), two of which correspond to cryptic sex Microchromosomes detectable only with high-resolution cytogenetic techniques. Sex chromosomes were undetected in previous studies of Emydura macquarii, a GSD side-necked turtle. Using comparative genomic hybridization (CGH) and GTG-banding, a heteromorphic XX/XY sex chromosome system was detected in E. macquarii . The Y chromosome appears submetacentric and somewhat larger than the metacentric X, the first such report for turtles. CGH revealed a male-specific chromosomal region, which appeared heteromorphic using GTG-banding, and was restricted to the telomeric region of the p arm. Based on our observations and the current phylogeny of chelid turtles, we hypothesize that the sex chromosomes of E. macquarii might be the result of a translocation of an ancestral Y Microchromosome as found in a turtle belonging to a sister clade, Chelodina longicollis , onto the tip of an autosome. However, in the absence of data from an outgroup, the opposite (fission of a large XY into an autosome and a micro-XY) is theoretically equally likely. Alternatively, the sex chromosome systems of E. macquarii and C. longicollis may have evolved independently. We discuss the potential causes and consequences of such putative chromosome rearrangements in the evolution of sex chromosomes and sex-determining systems of turtles in general.
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An XX/XY sex Microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination
Chromosome Research, 2006Co-Authors: Tariq Ezaz, Russell L. Burke, Nicole Valenzuela, Ikuo Miura, Arthur Georges, Frank Grützner, Jennifer A. Marshall-gravesAbstract:Heteromorphic sex chromosomes are rare in turtles, having been described in only four species. Like many turtle species, the Australian freshwater turtle Chelodina longicollis has genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes were identified in a previous karyotyping study. We used comparative genomic hybridization (CGH) to show that C. longicollis has an XX/XY system of chromosomal sex determination, involving a pair of Microchromosomes. C-banding and reverse fluorescent staining also distinguished Microchromosomes with different banding patterns in males and females in ∼70% cells examined. GTG-banding did not reveal any heteromorphic chromosomes, and no replication asynchrony on the X or Y Microchromosomes was observed using replication banding. We conclude that there is a very small sequence difference between X and Y chromosomes in this species, a difference that is consistently detectable only by high-resolution molecular cytogenetic techniques, such as CGH. This is the first time a pair of Microchromosomes has been identified as the sex chromosomes in a turtle species.
Arthur Georges - One of the best experts on this subject based on the ideXlab platform.
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Chromosome painting with V. acanthurus Microchromosome probes.
2014Co-Authors: Kazumi Matsubara, Arthur Georges, Yoichi Matsuda, Stephen D. Sarre, Jennifer Marshall A. Graves, Tariq EzazAbstract:Painting with the W chromosome probe in female V. acanthurus (a), the large Microchromosome probe in female V. acanthurus (b), an autosomal Microchromosome probe in male (c) and female V. acanthurus (d), and the W chromosome probe in female V. rosenbergi (e) and V. gouldii (f). Arrowheads indicate hybridization signals. ‘W’, ‘Lm’ and ‘m’ indicate W chromosomes in the three species (a, b, d–f), large Microchromosomes in male and female V. acanthurus (a–d), and Microchromosome to which the probe has been hybridized in male and female V. acanthurus (c, d), respectively. Scale bars indicate 10 µm.
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Extension, single-locus conversion and physical mapping of sex chromosome sequences identify the Z Microchromosome and pseudo-autosomal region in a dragon lizard, Pogona vitticeps
Heredity, 2009Co-Authors: Alexander E. Quinn, Tariq Ezaz, Stephen D. Sarre, J.a. Marshall Graves, Arthur GeorgesAbstract:Distribution of temperature-dependent sex determination (TSD) and genotypic sex determination (GSD) across the phylogeny of dragon lizards implies multiple independent origins of at least one, and probably both, modes of sex determination. Female Pogona vitticeps are the heterogametic sex, but ZZ individuals reverse to a female phenotype at high incubation temperatures. We used reiterated genome walking to extend Z and W chromosome-linked amplified fragment length polymorphism (AFLP) markers, and fluorescence in situ hybridization for physical mapping. One extended fragment hybridized to both W and Z Microchromosomes, identifying the Z Microchromosome for the first time, and a second hybridized to the centromere of all Microchromosomes. W-linked sequences were converted to a single-locus PCR sexing assay. P. vitticeps sex chromosome sequences also shared homology with several other Australian dragons. Further physical mapping and isolation of sex-specific bacterial artificial chromosome clones will provide insight into the evolution of sex determination and sex chromosomes in GSD and TSD dragon lizards.
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An XX/XY heteromorphic sex chromosome system in the Australian chelid turtle Emydura macquarii: A new piece in the puzzle of sex chromosome evolution in turtles
Chromosome Research, 2008Co-Authors: Pedro Alonzo Martinez, Nicole Valenzuela, Tariq Ezaz, Arthur Georges, Jennifer A. Marshall-gravesAbstract:Chromosomal sex determination is the prevalent system found in animals but is rare among turtles. In fact, heteromorphic sex chromosomes are known in only seven of the turtles possessing genotypic sex determination (GSD), two of which correspond to cryptic sex Microchromosomes detectable only with high-resolution cytogenetic techniques. Sex chromosomes were undetected in previous studies of Emydura macquarii, a GSD side-necked turtle. Using comparative genomic hybridization (CGH) and GTG-banding, a heteromorphic XX/XY sex chromosome system was detected in E. macquarii . The Y chromosome appears submetacentric and somewhat larger than the metacentric X, the first such report for turtles. CGH revealed a male-specific chromosomal region, which appeared heteromorphic using GTG-banding, and was restricted to the telomeric region of the p arm. Based on our observations and the current phylogeny of chelid turtles, we hypothesize that the sex chromosomes of E. macquarii might be the result of a translocation of an ancestral Y Microchromosome as found in a turtle belonging to a sister clade, Chelodina longicollis , onto the tip of an autosome. However, in the absence of data from an outgroup, the opposite (fission of a large XY into an autosome and a micro-XY) is theoretically equally likely. Alternatively, the sex chromosome systems of E. macquarii and C. longicollis may have evolved independently. We discuss the potential causes and consequences of such putative chromosome rearrangements in the evolution of sex chromosomes and sex-determining systems of turtles in general.
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An XX/XY sex Microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination
Chromosome Research, 2006Co-Authors: Tariq Ezaz, Russell L. Burke, Nicole Valenzuela, Ikuo Miura, Arthur Georges, Frank Grützner, Jennifer A. Marshall-gravesAbstract:Heteromorphic sex chromosomes are rare in turtles, having been described in only four species. Like many turtle species, the Australian freshwater turtle Chelodina longicollis has genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes were identified in a previous karyotyping study. We used comparative genomic hybridization (CGH) to show that C. longicollis has an XX/XY system of chromosomal sex determination, involving a pair of Microchromosomes. C-banding and reverse fluorescent staining also distinguished Microchromosomes with different banding patterns in males and females in ∼70% cells examined. GTG-banding did not reveal any heteromorphic chromosomes, and no replication asynchrony on the X or Y Microchromosomes was observed using replication banding. We conclude that there is a very small sequence difference between X and Y chromosomes in this species, a difference that is consistently detectable only by high-resolution molecular cytogenetic techniques, such as CGH. This is the first time a pair of Microchromosomes has been identified as the sex chromosomes in a turtle species.
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the dragon lizard pogona vitticeps has zz zw micro sex chromosomes
Chromosome Research, 2005Co-Authors: Tariq Ezaz, Ikuo Miura, Arthur Georges, Stephen D. Sarre, Alexander E. Quinn, Jennifer Marshall A. GravesAbstract:The bearded dragon, Pogona vitticeps (Agamidae: Reptilia) is an agamid lizard endemic to Australia. Like crocodilians and many turtles, temperature-dependent sex determination (TSD) is common in agamid lizards, although many species have genotypic sex determination (GSD). P. vitticeps is reported to have GSD, but no detectable sex chromosomes. Here we used molecular cytogenetic and differential banding techniques to reveal sex chromosomes in this species. Comparative genomic hybridization (CGH), GTG- and C-banding identified a highly heterochromatic Microchromosome specific to females, demonstrating female heterogamety (ZZ/ZW) in this species. We isolated the P. vitticeps W chromosome by microdissection, re-amplified the DNA and used it to paint the W. No unpaired bivalents were detected in male synaptonemal complexes at meiotic pachytene, confirming male homogamety. We conclude that P. vitticeps has differentiated previously unidentifable W and Z micro-sex chromosomes, the first to be demonstrated in an agamid lizard. Our finding implies that heterochromatinization of the heterogametic chromosome occurred during sex chromosome differentiation in this species, as is the case in some lizards and many snakes, as well as in birds and mammals. Many GSD reptiles with cryptic sex chromosomes may also prove to have micro-sex chromosomes. Reptile Microchromosomes, long dismissed as non-functional minutiae and often omitted from karyotypes, therefore deserve closer scrutiny with new and more sensitive techniques.
Yoichi Matsuda - One of the best experts on this subject based on the ideXlab platform.
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Molecular cytogenetic characterization of repetitive sequences comprising centromeric heterochromatin in three Anseriformes species - Fig 3
2019Co-Authors: Yoshinobu Uno, Satoshi Ishishita, Chizuko Nishida, Ayano Hata, Yoichi MatsudaAbstract:Chromosome painting with chicken (G. gallus, GGA) chromosome-specific DNA probes to Hoechst-stained chromosome spreads of A. fabalis (A‒C) and C. cygnus females (D‒E). DIG-labeled GGA1 (red) and biotin-labeled GGA9 (green) hybridized to chromosomes 1 and 9, respectively (A, D). DIG-labeled GGA4 (red) hybridized to chromosome 4 and a pair of Microchromosomes, and biotin-labeled GGA6 (green) hybridized to chromosome 6 (B, E). DIG-labeled GGA3 (red) hybridized to chromosome 3, and biotin-labeled GGA7 (green) hybridized to chromosome 7 (C). DIG-labeled painting probe of 20 Microchromosome pairs hybridized to approximately half of the Microchromosomes (F). Scale bars represent 10 μm.
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Molecular cytogenetic characterization of repetitive sequences comprising centromeric heterochromatin in three Anseriformes species
2019Co-Authors: Yoshinobu Uno, Satoshi Ishishita, Chizuko Nishida, Ayano Hata, Yoichi MatsudaAbstract:The highly repetitive DNA sequence of centromeric heterochromatin is an effective molecular cytogenetic marker for investigating genomic compartmentalization between macrochromosomes and Microchromosomes in birds. We isolated four repetitive sequence families of centromeric heterochromatin from three Anseriformes species, viz., domestic duck (Anas platyrhynchos, APL), bean goose (Anser fabalis, AFA), and whooper swan (Cygnus cygnus, CCY), and characterized the sequences by molecular cytogenetic approach. The 190-bp APL-HaeIII and 101-bp AFA-HinfI-S sequences were localized in almost all chromosomes of A. platyrhynchos and A. fabalis, respectively. However, the 192-bp AFA-HinfI-L and 290-bp CCY-ApaI sequences were distributed in almost all Microchromosomes of A. fabalis and in approximately 10 Microchromosomes of C. cygnus, respectively. APL-HaeIII, AFA-HinfI-L, and CCY-ApaI showed partial sequence homology with the chicken nuclear-membrane-associated (CNM) repeat families, which were localized primarily to the centromeric regions of Microchromosomes in Galliformes, suggesting that ancestral sequences of the CNM repeat families are observed in the common ancestors of Anseriformes and Galliformes. These results collectively provide the possibility that homogenization of centromeric heterochromatin occurred between Microchromosomes in Anseriformes and Galliformes; however, homogenization between macrochromosomes and Microchromosomes also occurred in some centromeric repetitive sequences.
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Microchromosome Disappearance in Gekkota
2016Co-Authors: Kornsorn Srikulnath, Chizuko Nishida, Yoshinobu Uno, Hidetoshi Ota, Yoichi MatsudaAbstract:The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromo-some number 2n = 38, with no Microchromosomes. For molecular cytogenetic characteriza-tion of the gekkotan karyotype, we constructed a cytogenetic map forG. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many Microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal Microchromosomes. Ten pairs ofG. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilismacrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera micro-chromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of Microchromosomes may hav
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Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis, Gekkonidae): The Process of Microchromosome Disappearance in Gekkota.
PloS one, 2015Co-Authors: Kornsorn Srikulnath, Chizuko Nishida, Yoshinobu Uno, Hidetoshi Ota, Yoichi MatsudaAbstract:The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no Microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many Microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal Microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera Microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of Microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of Microchromosomes and appearance of small-sized macrochromosomes.
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Identification of the linkage group of the Z sex chromosomes of the sand lizard (Lacerta agilis, Lacertidae) and elucidation of karyotype evolution in lacertid lizards
Chromosoma, 2014Co-Authors: Kornsorn Srikulnath, Chizuko Nishida, Kazumi Matsubara, Mats Olsson, Yoichi MatsudaAbstract:The sand lizard ( Lacerta agilis , Lacertidae) has a chromosome number of 2n = 38, with 17 pairs of acrocentric chromosomes, one pair of Microchromosomes, a large acrocentric Z chromosome, and a micro-W chromosome. To investigate the process of karyotype evolution in L. agilis , we performed chromosome banding and fluorescent in situ hybridization for gene mapping and constructed a cytogenetic map with 86 functional genes. Chromosome banding revealed that the Z chromosome is the fifth largest chromosome. The cytogenetic map revealed homology of the L. agilis Z chromosome with chicken chromosomes 6 and 9. Comparison of the L. agilis cytogenetic map with those of four Toxicofera species with many Microchromosomes ( Elaphe quadrivirgata , Varanus salvator macromaculatus , Leiolepis reevesii rubritaeniata , and Anolis carolinensis ) showed highly conserved linkage homology of L. agilis chromosomes (LAG) 1, 2, 3, 4, 5(Z), 7, 8, 9, and 10 with macrochromosomes and/or macrochromosome segments of the four Toxicofera species. Most of the genes located on the Microchromosomes of Toxicofera were localized to LAG6, small acrocentric chromosomes (LAG11–18), and a Microchromosome (LAG19) in L. agilis . These results suggest that the L. agilis karyotype resulted from frequent fusions of Microchromosomes, which occurred in the ancestral karyotype of Toxicofera and led to the disappearance of Microchromosomes and the appearance of many small macrochromosomes.
Valerie Fillon - One of the best experts on this subject based on the ideXlab platform.
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Chicken Microchromosomes in the Lampbrush Phase: A Cytogenetic Description.
Cytogenetic and genome research, 2017Co-Authors: Svetlana Galkina, Valerie Fillon, Alsu Saifitdinova, Aleksandra Daks, M. Kulak, Alexander Dyomin, Elena I. Koshel, Elena GaginskayaAbstract:Lampbrush chromosomes are giant, transcriptionally active, meiotic chromosomes found in oocytes of all vertebrates with the exception of mammals. Lampbrush chromosomes offer a convenient tool for cytogenetic mapping and, in particular, have been instrumental in mapping genes and linkage groups on chicken (GGA) chromosomes. Whereas cytogenetic maps of macrochromosome GGA1-10 and Microchromosome GGA11-16 lampbrush bivalents have been established, identification and description of smaller Microchromosome bivalents are still missing. In this work, we used specific FISH probes for the identification of 12 chicken lampbrush chromosomes formed by GGA17-28. Our observations on chromomere and lateral loop arrangement and chiasma position allowed us to construct the respective cytogenetic maps for these Microchromosomes. For the 10 smallest chicken Microchromosomes, GGA29-38, no individual molecular tags are available, yet they can be collectively marked using the PO41 repeat. The reported results contribute to building of working cytogenetic maps of the chicken karyotype.
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Chicken Microchromosomes in the Lampbrush Phase : A Cytogenetic Description
Cytogenetic and Genome Research, 2017Co-Authors: Svetlana Galkina, Valerie Fillon, Alsu Saifitdinova, Aleksandra Daks, M. Kulak, Alexander Dyomin, Elena I. Koshel, Elena GaginskayaAbstract:Lampbrush chromosomes are giant, transcriptionally active, meiotic chromosomes found in oocytes of all vertebrates with the exception of mammals. Lampbrush chromosomes offer a convenient tool for cytogenetic mapping and, in particular, have been instrumental in mapping genes and linkage groups on chicken (GGA) chromosomes. Whereas cytogenetic maps of macrochromosome GGA1-10 and Microchromosome GGA11-16 lampbrush bivalents have been established, identification and description of smaller Microchromosome bivalents are still missing. In this work, we used specific FISH probes for the identification of 12 chicken lampbrush chromosomes formed by GGA17-28. Our observations on chromomere and lateral loop arrangement and chiasma position allowed us to construct the respective cytogenetic maps for these Microchromosomes. For the 10 smallest chicken Microchromosomes, GGA29-38, no individual molecular tags are available, yet they can be collectively marked using the PO41 repeat. The reported results contribute to building of working cytogenetic maps of the chicken karyotype. (C) 2017 S.Karger AG, Basel Keywords
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Addition of the Microchromosome GGA25 to the chicken genome sequence assembly through radiation hybrid and genetic mapping
BMC genomics, 2008Co-Authors: Marine Douaud, Valerie Fillon, Katia Feve, Marie Gerus, Suzanne Bardes, David Gourichon, Deborah A. Dawson, Olivier Hanotte, Terry Burke, Florence VignolesAbstract:Background The publication of the first draft chicken sequence assembly became available in 2004 and was updated in 2006. However, this does not constitute a definitive and complete sequence of the chicken genome, since the Microchromosomes are notably under-represented. In an effort to develop maps for the Microchromosomes absent from the chicken genome assembly, we developed radiation hybrid (RH) and genetic maps with markers isolated from sequence currently assigned to "chromosome Unknown" (chrUn). The chrUn is composed of sequence contigs not assigned to named chromosomes. To identify and map sequence belonging to the Microchromosomes we used a comparative mapping strategy, and we focused on the small linkage group E26C13.
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FISH mapping of 57 BAC clones reveals strong conservation of synteny between Galliformes and Anseriformes.
Animal genetics, 2007Co-Authors: Valerie Fillon, M. Vignoles, Richard P M A Crooijmans, Martien A. M. Groenen, R. Zoorob, Alain VignalAbstract:Karyotypes of chicken (Gallus gallus domesticus; 2n = 78) and mallard duck (Anas platyrhynchos; 2n = 80) share the typical organization of avian karyotypes including a few macrochromosome pairs, numerous indistinguishable Microchromosomes, and Z and W sex chromosomes. Previous banding studies revealed great similarities between chickens and ducks, but it was not possible to use comparative banding for the Microchromosomes. In order to establish precise chromosome correspondences between these two species, particularly for Microchromosomes, we hybridized 57 BAC clones previously assigned to the chicken genome to duck metaphase spreads. Although most of the clones showed similar localizations, we found a few intrachromosomal rearrangements of the macrochromosomes and an additional Microchromosome pair in ducks. BAC clones specific for chicken Microchromosomes were localized to separate duck Microchromosomes and clones mapping to the same chicken Microchromosome hybridized to the same duck Microchromosome, demonstrating a high conservation of synteny. These results demonstrate that the evolution of karyotypes in avian species is the result of fusion and/or fission processes and not translocations.
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integrated maps in quail coturnix japonica confirm the high degree of synteny conservation with chicken gallus gallus despite 35 million years of divergence
BMC Genomics, 2006Co-Authors: Valerie Fillon, Boniface B Kayang, Miho Inouemurayama, Mitsuru Miwa, Sophie Leroux, Katia Feve, J L Monvoisin, Frederique Pitel, M. VignolesAbstract:By comparing the quail genome with that of chicken, chromosome rearrangements that have occurred in these two galliform species over 35 million years of evolution can be detected. From a more practical point of view, the definition of conserved syntenies helps to predict the position of genes in quail, based on information taken from the chicken sequence, thus enhancing the utility of this species in biological studies through a better knowledge of its genome structure. A microsatellite and an Amplified Fragment Length Polymorphism (AFLP) genetic map were previously published for quail, as well as comparative cytogenetic data with chicken for macrochromosomes. Quail genomics will benefit from the extension and the integration of these maps. The integrated linkage map presented here is based on segregation analysis of both anonymous markers and functional gene loci in 1,050 quail from three independent F2 populations. Ninety-two loci are resolved into 14 autosomal linkage groups and a Z chromosome-specific linkage group, aligned with the quail AFLP map. The size of linkage groups ranges from 7.8 cM to 274.8 cM. The total map distance covers 904.3 cM with an average spacing of 9.7 cM between loci. The coverage is not complete, as macrochromosome CJA08, the gonosome CJAW and 23 Microchromosomes have no marker assigned yet. Significant sequence identities of quail markers with chicken enabled the alignment of the quail linkage groups on the chicken genome sequence assembly. This, together with interspecific Fluorescence In Situ Hybridization (FISH), revealed very high similarities in marker order between the two species for the eight macrochromosomes and the 14 Microchromosomes studied. Integrating the two microsatellite and the AFLP quail genetic maps greatly enhances the quality of the resulting information and will thus facilitate the identification of Quantitative Trait Loci (QTL). The alignment with the chicken chromosomes confirms the high conservation of gene order that was expected between the two species for macrochromosomes. By extending the comparative study to the Microchromosomes, we suggest that a wealth of information can be mined in chicken, to be used for genome analyses in quail.