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Retroposed SNOfall—A mammalian-wide comparison of platypus snoRNAs

Schmitz, Jürgen; Zemann, Anja; Churakov, Gennady; Kuhl, Heiner; Grützner, Frank; Reinhardt, Richard; Brosius, Jürgen
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /06/2008 EN
Relevância na Pesquisa
37.71%
Diversification of mammalian species began more than 160 million years ago when the egg-laying monotremes diverged from live bearing mammals. The duck-billed platypus (Ornithorhynchus anatinus) and echidnas are the only potential contemporary witnesses of this period and, thereby, provide a unique insight into mammalian genome evolution. It has become clear that small RNAs are major regulatory agents in eukaryotic cells, and the significant role of non-protein-coding (npc) RNAs in transcription, processing, and translation is now well accepted. Here we show that the platypus genome contains more than 200 small nucleolar (sno) RNAs among hundreds of other diverse npcRNAs. Their comparison among key mammalian groups and other vertebrates enabled us to reconstruct a complete temporal pathway of acquisition and loss of these snoRNAs. In platypus we found cis- and trans-duplication distribution patterns for snoRNAs, which have not been described in any other vertebrates but are known to occur in nematodes. An exciting novelty in platypus is a snoRNA-derived retroposon (termed snoRTE) that facilitates a very effective dispersal of an H/ACA snoRNA via RTE-mediated retroposition. From more than 40,000 detected full-length and truncated genomic copies of this snoRTE...

Defensins and the convergent evolution of platypus and reptile venom genes

Whittington, Camilla M.; Papenfuss, Anthony T.; Bansal, Paramjit; Torres, Allan M.; Wong, Emily S.W.; Deakin, Janine E.; Graves, Tina; Alsop, Amber; Schatzkamer, Kyriena; Kremitzki, Colin; Ponting, Chris P.; Temple-Smith, Peter; Warren, Wesley C.; Kuchel,
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /06/2008 EN
Relevância na Pesquisa
37.87%
When the platypus (Ornithorhynchus anatinus) was first discovered, it was thought to be a taxidermist’s hoax, as it has a blend of mammalian and reptilian features. It is a most remarkable mammal, not only because it lays eggs but also because it is venomous. Rather than delivering venom through a bite, as do snakes and shrews, male platypuses have venomous spurs on each hind leg. The platypus genome sequence provides a unique opportunity to unravel the evolutionary history of many of these interesting features. While searching the platypus genome for the sequences of antimicrobial defensin genes, we identified three Ornithorhynchus venom defensin-like peptide (OvDLP) genes, which produce the major components of platypus venom. We show that gene duplication and subsequent functional diversification of beta-defensins gave rise to these platypus OvDLPs. The OvDLP genes are located adjacent to the beta-defensins and share similar gene organization and peptide structures. Intriguingly, some species of snakes and lizards also produce venoms containing similar molecules called crotamines and crotamine-like peptides. This led us to trace the evolutionary origins of other components of platypus and reptile venom. Here we show that several venom components have evolved separately in the platypus and reptiles. Convergent evolution has repeatedly selected genes coding for proteins containing specific structural motifs as templates for venom molecules.

Conservation of small RNA pathways in platypus

Murchison, Elizabeth P.; Kheradpour, Pouya; Sachidanandam, Ravi; Smith, Carly; Hodges, Emily; Xuan, Zhenyu; Kellis, Manolis; Grützner, Frank; Stark, Alexander; Hannon, Gregory J.
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /06/2008 EN
Relevância na Pesquisa
37.71%
Small RNA pathways play evolutionarily conserved roles in gene regulation and defense from parasitic nucleic acids. The character and expression patterns of small RNAs show conservation throughout animal lineages, but specific animal clades also show variations on these recurring themes, including species-specific small RNAs. The monotremes, with only platypus and four species of echidna as extant members, represent the basal branch of the mammalian lineage. Here, we examine the small RNA pathways of monotremes by deep sequencing of six platypus and echidna tissues. We find that highly conserved microRNA species display their signature tissue-specific expression patterns. In addition, we find a large rapidly evolving cluster of microRNAs on platypus chromosome X1, which is unique to monotremes. Platypus and echidna testes contain a robust Piwi-interacting (piRNA) system, which appears to be participating in ongoing transposon defense.

How did the platypus get its sex chromosome chain? A comparison of meiotic multiples and sex chromosomes in plants and animals

Grutzner, F.; Ashley, T.; Rowell, D.; Graves, J.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
37.62%
The duck-billed platypus is an extraordinary mammal. Its chromosome complement is no less extraordinary, for it includes a system in which ten sex chromosomes form an extensive meiotic chain in males. Such meiotic multiples are unprecedented in vertebrates but occur sporadically in plant and invertebrate species. In this paper, we review the evolution and formation of meiotic multiples in plants and invertebrates to try to gain insights into the origin of the platypus meiotic multiple. We describe the meiotic hurdles that translocated mammalian chromosomes face, which make longer chains disadvantageous in mammals, and we discuss how sex chromosomes and dosage compensation might have affected the evolution of sex-linked meiotic multiples. We conclude that the evolutionary conservation of the chain in monotremes, the structural properties of the translocated chromosomes and the highly accurate segregation at meiosis make the platypus system remarkably different from meiotic multiples in other species. We discuss alternative evolutionary models, which fall broadly into two categories: either the chain is the result of a sequence of translocation events from an ancestral pair of sex chromosomes (Model I) or the entire chain came into being at once by hybridization of two populations with different chromosomal rearrangements sharing monobrachial homology (Model II).; Frank Gruetzner...

DMRT gene cluster analysis in the platypus: New insights into genomic organization and regulatory regions

El-Mogharbel, N.; Wakefield, M.; Deakin, J.; Tsend-Ayush, E.; Grutzner, F.; Alsop, A.; Ezaz, T.; Graves, J.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.9%
We isolated and characterized a cluster of platypus DMRT genes and compared their arrangement, location, and sequence across vertebrates. The DMRT gene cluster on human 9p24.3 harbors, in order, DMRT1, DMRT3, and DMRT2, which share a DM domain. DMRT1 is highly conserved and involved in sexual development in vertebrates, and deletions in this region cause sex reversal in humans. Sequence comparisons of DMRT genes between species have been valuable in identifying exons, control regions, and conserved nongenic regions (CNGs). The addition of platypus sequences is expected to be particularly valuable, since monotremes fill a gap in the vertebrate genome coverage. We therefore isolated and fully sequenced platypus BAC clones containing DMRT3 and DMRT2 as well as DMRT1 and then generated multispecies alignments and ran prediction programs followed by experimental verification to annotate this gene cluster. We found that the three genes have 58-66% identity to their human orthologues, lie in the same order as in other vertebrates, and colocate on 1 of the 10 platypus sex chromosomes, X5. We also predict that optimal annotation of the newly sequenced platypus genome will be challenging. The analysis of platypus sequence revealed differences in structure and sequence of the DMRT gene cluster. Multispecies comparison was particularly effective for detecting CNGs...

Sex determination in platypus and echidna: autosomal location of SOX3 confirms the absence of SRY from monotremes

Wallis, M.; Waters, P.; Delbridge, M.; Kirby, P.; Pask, A.; Grutzner, F.; Rens, W.; Ferguson-Smith, M.; Graves, J.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.71%
In eutherian (‘placental’) mammals, sex is determined by the presence or absence of the Y chromosome-borne gene SRY, which triggers testis determination. Marsupials also have a Y-borne SRY gene, implying that this mechanism is ancestral to therians, the SRY gene having diverged from its X-borne homologue SOX3 at least 180 million years ago. The rare exceptions have clearly lost and replaced the SRY mechanism recently. Other vertebrate classes have a variety of sex-determining mechanisms, but none shares the therian SRY-driven XX female:XY male system. In monotreme mammals (platypus and echidna), which branched from the therian lineage 210 million years ago, no orthologue of SRY has been found. In this study we show that its partner SOX3 is autosomal in platypus and echidna, mapping among human X chromosome orthologues to platypus chromosome 6, and to the homologous chromosome 16 in echidna. The autosomal localization of SOX3 in monotreme mammals, as well as non-mammal vertebrates, implies that SRY is absent in Prototheria and evolved later in the therian lineage 210–180 million years ago. Sex determination in platypus and echidna must therefore depend on another male-determining gene(s) on the Y chromosomes, or on the different dosage of a gene(s) on the X chromosomes.; M. C. Wallis...

Retroposed SNOfall - A mammalian-wide comparison of platypus snoRNAs

Schmitz, J.; Zemann, A.; Churakov, G.; Kuhl, H.; Grutzner, F.; Reinhardt, R.; Brosius, J.
Fonte: Cold Spring Harbor Lab Press Publicador: Cold Spring Harbor Lab Press
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.71%
Diversification of mammalian species began more than 160 million years ago when the egg-laying monotremes diverged from live bearing mammals. The duck-billed platypus (Ornithorhynchus anatinus) and echidnas are the only potential contemporary witnesses of this period and, thereby, provide a unique insight into mammalian genome evolution. It has become clear that small RNAs are major regulatory agents in eukaryotic cells, and the significant role of non-protein-coding (npc) RNAs in transcription, processing, and translation is now well accepted. Here we show that the platypus genome contains more than 200 small nucleolar (sno) RNAs among hundreds of other diverse npcRNAs. Their comparison among key mammalian groups and other vertebrates enabled us to reconstruct a complete temporal pathway of acquisition and loss of these snoRNAs. In platypus we found cis- and trans-duplication distribution patterns for snoRNAs, which have not been described in any other vertebrates but are known to occur in nematodes. An exciting novelty in platypus is a snoRNA-derived retroposon (termed snoRTE) that facilitates a very effective dispersal of an H/ACA snoRNA via RTE-mediated retroposition. From more than 40,000 detected full-length and truncated genomic copies of this snoRTE...

Bird-like sex chromosomes of platypus imply recent origin of mammal sex chromosomes

Veyrunes, F.; Waters, P.; Miethke, P.; Rens, W.; McMillan, D.; Alsop, A.; Grutzner, F.; Deakin, J.; Whittington, C.; Schatzkamer, K.; Kremitzki, C.; Graves, T.; Ferguson-Smith, M.; Warren, W.; Graves, J.
Fonte: Cold Spring Harbor Lab Press Publicador: Cold Spring Harbor Lab Press
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.78%
In therian mammals (placentals and marsupials), sex is determined by an XX female: XY male system, in which a gene (SRY) on the Y affects male determination. There is no equivalent in other amniotes, although some taxa (notably birds and snakes) have differentiated sex chromosomes. Birds have a ZW female: ZZ male system with no homology with mammal sex chromosomes, in which dosage of a Z-borne gene (possibly DMRT1) affects male determination. As the most basal mammal group, the egg-laying monotremes are ideal for determining how the therian XY system evolved. The platypus has an extraordinary sex chromosome complex, in which five X and five Y chromosomes pair in a translocation chain of alternating X and Y chromosomes. We used physical mapping to identify genes on the pairing regions between adjacent X and Y chromosomes. Most significantly, comparative mapping shows that, contrary to earlier reports, there is no homology between the platypus and therian X chromosomes. Orthologs of genes in the conserved region of the human X (including SOX3, the gene from which SRY evolved) all map to platypus chromosome 6, which therefore represents the ancestral autosome from which the therian X and Y pair derived. Rather, the platypus X chromosomes have substantial homology with the bird Z chromosome (including DMRT1) and to segments syntenic with this region in the human genome. Thus...

Conservation of small RNA pathways in platypus

Murchison, E.; Kheradpour, P.; Sachidanandam, R.; Smith, C.; Hodges, E.; Xuan, Z.; Kellis, M.; Grutzner, F.; Stark, A.; Hannon, G.
Fonte: Cold Spring Harbor Lab Press Publicador: Cold Spring Harbor Lab Press
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.71%
Small RNA pathways play evolutionarily conserved roles in gene regulation and defense from parasitic nucleic acids. The character and expression patterns of small RNAs show conservation throughout animal lineages, but specific animal clades also show variations on these recurring themes, including species-specific small RNAs. The monotremes, with only platypus and four species of echidna as extant members, represent the basal branch of the mammalian lineage. Here, we examine the small RNA pathways of monotremes by deep sequencing of six platypus and echidna tissues. We find that highly conserved microRNA species display their signature tissue-specific expression patterns. In addition, we find a large rapidly evolving cluster of microRNAs on platypus chromosome X1, which is unique to monotremes. Platypus and echidna testes contain a robust Piwi-interacting (piRNA) system, which appears to be participating in ongoing transposon defense.; Elizabeth P. Murchison, Pouya Kheradpour, Ravi Sachidanandam, Carly Smith, Emily Hodges, Zhenyu Xuan, Manolis Kellis, Frank Grützner, Alexander Stark, and Gregory J. Hannon; Copyright © 2008 by Cold Spring Harbor Laboratory Press Orginally published online May 7, 2008

Platypus Pou5f1 reveals the first steps in the evolution of trophectoderm differentiation and pluripotency in mammals

Niwa, H.; Sekita, Y.; Tsend-Ayush, E.; Grutzner, F.
Fonte: Blackwell Publishing Inc Publicador: Blackwell Publishing Inc
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.78%
SUMMARY Uterine nourishment of embryos by the placenta is a key feature of mammals. Although a variety of placenta types exist, they are all derived from the trophectoderm (TE) cell layer of the developing embryo. Egg-laying mammals (platypus and echidnas) are distinguished by a very short intrauterine embryo development, in which a simple placenta forms from TE-like cells. The Pou5f1 gene encodes a class V POU family transcription factor Oct3/4. In mice, Oct3/4 together with the highly conserved caudal-related homeobox transcription factor Cdx2, determines TE fate in pre-implantation development. In contrast to Cdx2, Pou5f1 has only been identified in eutherian mammals and marsupials, whereas, in other vertebrates, pou2 is considered to be the Pou5f1 ortholog. Here, we show that platypus and opossum genomes contain a Pou5f1 and pou2 homolog, pou2-related, indicating that these two genes are paralogues and arose by gene duplication in early mammalian evolution. In a complementation assay, we found that platypus or human Pou5f1, but not opossum or zebrafish pou2, restores self-renewal in Pou5f1-null mouse ES cells, showing that platypus possess a fully functional Pou5f1 gene. Interestingly, we discovered that parts of one of the conserved regions (CR4) is missing from the platypus Pou5f1 promoter...

Loss of genes implicated in gastric function during platypus evolution

Ordonez, G.; Hillier, L.; Warren, W.; Grutzner, F.; Lopez-Otin, C.; Puente, X.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.83%
Background The duck-billed platypus (Ornithorhynchus anatinus) belongs to the mammalian subclass Prototheria, which diverged from the Theria line early in mammalian evolution. The platypus genome sequence provides a unique opportunity to illuminate some aspects of the biology and evolution of these animals. Results We show that several genes implicated in food digestion in the stomach have been deleted or inactivated in platypus. Comparison with other vertebrate genomes revealed that the main genes implicated in the formation and activity of gastric juice have been lost in platypus. These include the aspartyl proteases pepsinogen A and pepsinogens B/C, the hydrochloric acid secretion stimulatory hormone gastrin, and the α subunit of the gastric H+/K+-ATPase. Other genes implicated in gastric functions, such as the β subunit of the H+/K+-ATPase and the aspartyl protease cathepsin E, have been inactivated because of the acquisition of loss-of-function mutations. All of these genes are highly conserved in vertebrates, reflecting a unique pattern of evolution in the platypus genome not previously seen in other mammalian genomes. Conclusion The observed loss of genes involved in gastric functions might be responsible for the anatomical and physiological differences in gastrointestinal tract between monotremes and other vertebrates...

Higher-order genome organization in platypus and chicken sperm and repositioning of sex chromosomes during mammalian evolution

Tsend-Ayush, E.; Dodge, N.; Mohr, J.; Casey, A.; Himmelbauer, H.; Kremitzki, C.; Schatzkamer, K.; Graves, T.; Warren, W.; Grutzner, F.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
37.78%
In mammals, chromosomes occupy defined positions in sperm, whereas previous work in chicken showed random chromosome distribution. Monotremes (platypus and echidnas) are the most basal group of living mammals. They have elongated sperm like chicken and a complex sex chromosome system with homology to chicken sex chromosomes. We used platypus and chicken genomic clones to investigate genome organization in sperm. In chicken sperm, about half of the chromosomes investigated are organized non-randomly, whereas in platypus chromosome organization in sperm is almost entirely non-random. The use of genomic clones allowed us to determine chromosome orientation and chromatin compaction in sperm. We found that in both species chromosomes maintain orientation of chromosomes in sperm independent of random or non-random positioning along the sperm nucleus. The distance of loci correlated with the total length of sperm nuclei, suggesting that chromatin extension depends on sperm elongation. In platypus, most sex chromosomes cluster in the posterior region of the sperm nucleus, presumably the result of postmeiotic association of sex chromosomes. Chicken and platypus autosomes sharing homology with the human X chromosome located centrally in both species suggesting that this is the ancestral position. This suggests that in some therian mammals a more anterior position of the X chromosome has evolved independently.; Enkhjargal Tsend-Ayush...

Genome analysis of the platypus reveals unique signatures of evolution

Warren, W.; Hillier, L.; Graves, J.; Birney, E.; Ponting, C.; Grutzner, F.; Belov, K.; Miller, W.; Clarke, L.; Chinwall, A.; Yang, S.P.; Heger, A.; Locke, D.; Miethke, P.; Waters, P.; Veyrunes, F.; Fulton, L.; Fulton, B.; Graves, T.; Wallis, J.; et al.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.71%
We present a draft genome sequence of the platypus, Ornithorhynchus anatinus. This monotreme exhibits a fascinating combination of reptilian and mammalian characters. For example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with venom similar to that of reptiles. Analysis of the first monotreme genome aligned these features with genetic innovations. We find that reptile and platypus venom proteins have been co-opted independently from the same gene families; milk protein genes are conserved despite platypuses laying eggs; and immune gene family expansions are directly related to platypus biology. Expansions of protein, non-protein-coding RNA and microRNA families, as well as repeat elements, are identified. Sequencing of this genome now provides a valuable resource for deep mammalian comparative analyses, as well as for monotreme biology and conservation.; Wesley C. Warren... Frank Grützner... Enkhjargal Tsend-Ayush... et al.

Insights into the evolution of mammalian telomerase: Platypus TERT shares similarities with genes of birds and other reptiles and localizes on sex chromosomes

Hrdlickova, R.; Nehyba, J.; Lim, S.; Grutzner, F.; Bose, H.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
37.71%
Background The TERT gene encodes the catalytic subunit of the telomerase complex and is responsible for maintaining telomere length. Vertebrate telomerase has been studied in eutherian mammals, fish, and the chicken, but less attention has been paid to other vertebrates. The platypus occupies an important evolutionary position, providing unique insight into the evolution of mammalian genes. We report the cloning of a platypus TERT (OanTERT) ortholog, and provide a comparison with genes of other vertebrates. Results The OanTERT encodes a protein with a high sequence similarity to marsupial TERT and avian TERT. Like the TERT of sauropsids and marsupials, as well as that of sharks and echinoderms, OanTERT contains extended variable linkers in the N-terminal region suggesting that they were present already in basal vertebrates and lost independently in rayfinned fish and eutherian mammals. Several alternatively spliced OanTERT variants structurally similar to avian TERT variants were identified. Telomerase activity is expressed in all platypus tissues like that of cold-blooded animals and murine rodents. OanTERT was localized on pseudoautosomal regions of sex chromosomes X3/Y2, expanding the homology between human chromosome 5 and platypus sex chromosomes. Synteny analysis suggests that TERT co-localized with sex-linked genes in the last common mammalian ancestor. Interestingly...

Immunohistochemical analysis of pancreatic islets of platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus ssp.)

He, C.; Myers, M.A.; Forbes, B.E.; Grützner, F.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
37.62%
Monotremes have undergone remarkable changes to their digestive and metabolic control system; however, the monotreme pancreas remains poorly characterized. Previous work in echidna demonstrated the presence of pancreatic islets, but no information is available for platypus and the fine structure has not been described for either monotreme. Based on our recent finding that monotremes lack the ghrelin gene, which is expressed in mouse and human pancreatic islets, we investigated the structure of monotreme islets in more detail. Generally, as in birds, the islets of monotremes were smaller but greater in number compared with mouse. β-cells were the most abundant endocrine cell population in platypus islets and were located peripherally, while α-cells were observed both in the interior and periphery of the islets. δ-cells and pancreatic polypeptide (PP)-cells were mainly found in the islet periphery. Distinct PP-rich (PP-lobe) and PP-poor areas (non-PP-lobe) are present in therian mammals, and we identified these areas in echidna but not platypus pancreas. Interestingly, in some of the echidna islets, α- and β-cells tended to form two poles within the islets, which to our knowledge is the first time this has been observed in any species. Overall...

In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes

Grutzner, F.; Rens, W.; Tsend-Ayush, E.; El-Mogharbel, N.; O'Brien, P.; Jones, R.; Ferguson-Smith, M.; Graves, J.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
Relevância na Pesquisa
37.62%
Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males1, or of both sexes2–4, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants5 and insects6 but are rare in vertebrates7. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades1– 4. Here we demonstrate that platypus have five malespecific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes). These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. Which, if any, of these sex chromosomes bears one or more sex-determining genes remains unknown. The largest X chromosome, with homology to the human X chromosome, lies at one end of the chain, and a chromosome with homology to the bird Z chromosome lies near the other end. This suggests an evolutionary link between mammal and bird sex chromosome systems, which were previously thought to have evolved independently.; Frank Grützner...

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

Patel, V.; Cooper, S.; Deakin, J.; Fulton, B.; Graves, T.; Warren, W.; Wilson, R.; Graves, J.
Fonte: BioMed Central Ltd. Publicador: BioMed Central Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
37.62%
Background: Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. Results: The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-αD-α3-α2-α1-ω-GBY-3'. The platypus β-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-ε-β-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate α-globin clusters are flanked by MPG-C16orf35 and LUC7L...

Mapping platypus SOX genes; autosomal location of SOX9 excludes it from sex determining role

Wallis, M.; Delbridge, M.; Pask, A.; Alsop, A.; Grutzner, F.; O'Brien, P.; Rens, W.; Ferguson-Smith, M.; Graves, J.
Fonte: Karger Publicador: Karger
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.83%
In the absence of an SRY orthologue the platypus sex determining gene is unknown, so genes in the human testis determining pathway are of particular interest as candidates. SOX9 is an attractive choice because SOX9 deletions cause male-to-female sex reversal in humans and mice, and SOX9 duplications cause female-to-male sex reversal. We have localized platypus SOX9, as well as the related SOX10, to platypus chromosomes 15 and 10, respectively, the first assignments to these platypus chromosomes, and the first comparative mapping markers from human chromosomes 17 and 22. The autosomal localization of platypus SOX9 in this study contradicts the hypothesis that SOX9 acts as the sex determining switch in platypus.; M.C. Wallis, M.L. Delbridge, A.J. Pask, A.E. Alsop, F. Grützner, P.C.M. O'Brien, W. Rens, M.A. Ferguson-Smith, J.A.M. Graves

Characterizing the chromosomes of the platypus (Ornithorhynchus anatinus)

McMillan, D.; Miethke, P.; Alsop, A.; Rens, W.; O'Brien, P.; Trifonov, V.; Veyrunes, F.; Schatzkamer, K.; Kremitzki, C.; Graves, T.; Warren, W.; Grutzner, F.; Ferguson-Smith, M.; Graves, J.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.62%
Like the unique platypus itself, the platypus genome is extraordinary because of its complex sex chromosome system, and is controversial because of difficulties in identification of small autosomes and sex chromosomes. A 6-fold shotgun sequence of the platypus genome is now available and is being assembled with the help of physical mapping. It is therefore essential to characterize the chromosomes and resolve the ambiguities and inconsistencies in identifying autosomes and sex chromosomes. We have used chromosome paints and DAPI banding to identify and classify pairs of autosomes and sex chromosomes. We have established an agreed nomenclature and identified anchor BAC clones for each chromosome that will ensure unambiguous gene localizations.; Daniel McMillan, Pat Miethke, Amber E. Alsop, Willem Rens, Patricia O’Brien, Vladimir Trifonov, Frederic Veyrunes, Kyriena Schatzkamer, Colin L. Kremitzki, Tina Graves, Wesley Warren, Frank Grützner, Malcolm A. Ferguson-Smith and Jennifer A. Marshall Graves; The definitive version may be found at www.springerlink.com

The multiple sex chromosomes of platypus and echidna are not completely identical and several share homology with the avian Z

Rens, Willem; O'Brien, Patricia CM; Grutzner, Frank; Clarke, Oliver; Graphodatskaya, Daria; Tsend-Ayush, Enkhjargal; Trifonov, Vladimir A; Skelton, Helen; Wallis, Mary C; Johnston, Steve; Veyrunes, Frederic; Graves, Jennifer AM; Ferguson-Smith, Malcolm A
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.87%
BACKGROUND Sex-determining systems have evolved independently in vertebrates. Placental mammals and marsupials have an XY system, birds have a ZW system. Reptiles and amphibians have different systems, including temperature-dependent sex determination, and XY and ZW systems that differ in origin from birds and placental mammals. Monotremes diverged early in mammalian evolution, just after the mammalian clade diverged from the sauropsid clade. Our previous studies showed that male platypus has five X and five Y chromosomes, no SRY, and DMRT1 on an X chromosome. In order to investigate monotreme sex chromosome evolution, we performed a comparative study of platypus and echidna by chromosome painting and comparative gene mapping. RESULTS Chromosome painting reveals a meiotic chain of nine sex chromosomes in the male echidna and establishes their order in the chain. Two of those differ from those in the platypus, three of the platypus sex chromosomes differ from those of the echidna and the order of several chromosomes is rearranged. Comparative gene mapping shows that, in addition to bird autosome regions, regions of bird Z chromosomes are homologous to regions in four platypus X chromosomes, that is, X1, X2, X3, X5, and in chromosome Y1. CONCLUSION Monotreme sex chromosomes are easiest to explain on the hypothesis that autosomes were added sequentially to the translocation chain...