Malcolm A Ferguson-Smith

University of Cambridge, Cambridge, England, United Kingdom

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Publications (91)475.58 Total impact

  • Malcolm A Ferguson-Smith, David R Goudie
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    ABSTRACT: Multiple self-healing squamous epithelioma (MSSE) is a rare familial skin cancer in which multiple tumours resembling crateriform squamous carcinomas are locally invasive but regress spontaneously after several months, leaving deep disfiguring facial scars and shallower scars on the limbs. First identified in a number of Scottish families, the condition has since been reported more widely. We review here the investigations leading to the discovery of loss of function mutations in TGFBR1 that are responsible for the disease. Loss of heterozygosity in tumours reveals that TGFBR1 acts as a tumour suppressor gene. TGFBR1 was initially excluded as the MSSE gene because it lies outside an extensive chromosome 9 haplotype shared by Scottish families. MSSE can now be regarded as a digenic/multilocus disease in view of the evidence of a second linked locus necessary for pathogenesis located within the Scottish haplotype.
    The international journal of biochemistry & cell biology 04/2014; · 4.89 Impact Factor
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    ABSTRACT: Avian genome organisation is characterised, in part, by a set of microchromosomes that are unusually small in size and unusually large in number. Although containing about a quarter of the genome, they contain around half the genes and three quarters of the total chromosome number. Nonetheless, they continue to belie analysis by cytogenetic means. Chromosomal rearrangements play a key role in genome evolution, fertility and genetic disease and thus tools for analysis of the microchromosomes are essential to analyse such phenomena in birds. Here, we report the development of chicken microchromosomal paint pools, generation of pairs of specific microchromosome BAC clones in chicken, and computational tools for in silico comparison of the genomes of microchromosomes. We demonstrate the use of these molecular and computational tools across species, suggesting their use to generate a clear picture of microchromosomal rearrangements between avian species. With increasing numbers of avian genome sequences that are emerging, tools such as these will find great utility in assembling genomes de novo and for asking fundamental questions about genome evolution from a chromosomal perspective.
    Chromosome Research 04/2014; · 2.85 Impact Factor
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    ABSTRACT: The Coscoroba (Coscoroba coscoroba), endemic to southern South America, is traditionally considered as an early branch from the common ancestor leading to true geese and swans. Recently, an interesting association between the Coscoroba and Cape Barren goose (Cereopsis novaehollandiae) as sister groups has been proposed. We present here the characterization of the karyotype of C. coscoroba using whole chromosome probes derived from Gallus gallus macrochromosomes. Our data showed that C. coscoroba has the highest diploid number among Anseriformes (2n = 98), and the conservation of macrochromosome pairs 1–10 indicates that the increase in diploid number has occurred by fission events involving only the microchromosomes. Moreover, the similarity between the diploid numbers of C. coscoroba (2n = 98) and Cereopsis novaehollandiae (2n = 92) reinforces the phylogenetic position of these two species as sister groups, considering that other species of geese and swans have diploid numbers close to 2n = 80
    Biological Journal of the Linnean Society 02/2014; 111:274-279. · 2.41 Impact Factor
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    ABSTRACT: Turdus rufiventris and Turdus albicollis, two songbirds belonging to the family Turdidae (Aves, Passeriformes) were studied by C-banding, 18S rDNA, as well as the use of whole chromosome probes derived from Gallus gallus (GGA) and Leucopternis albicollis (LAL). They showed very similar karyotypes, with 2n = 78 and the same pattern of distribution of heterochromatic blocks and hybridization patterns. However, the analysis of 18/28S rDNA has shown differences in the number of NOR-bearing chromosomes and ribosomal clusters. The hybridization pattern of GGA macrochromosomes was similar to the one found in songbirds studied by Fluorescent in situ hybridization, with fission of GGA 1 and GGA 4 chromosomes. In contrast, LAL chromosome paintings revealed a complex pattern of intrachromosomal rearrangements (paracentric and pericentric inversions) on chromosome 2, which corresponds to GGA1q. The first inversion changed the chromosomal morphology and the second and third inversions changed the order of chromosome segments. Karyotype analysis in Turdus revealed that this genus has derived characteristics in relation to the putative avian ancestral karyotype, highlighting the importance of using new tools for analysis of chromosomal evolution in birds, such as the probes derived from L. albicollis, which make it possible to identify intrachromosomal rearrangements not visible with the use of GGA chromosome painting solely.
    PLoS ONE 01/2014; 9(7):e103338. · 3.53 Impact Factor
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    ABSTRACT: The genus Micronycteris is a diverse group of phyllostomid bats currently comprising 11 species, with diploid number (2n) ranging from 26 to 40 chromosomes. The karyotypic relationships within Micronycteris and between Micronycteris and other phyllostomids remain poorly understood. The karyotype of Micronycteris hirsuta is of particular interest: three different diploid numbers were reported for this species in South and Central Americas with 2n = 26, 28 and 30 chromosomes. Although current evidence suggests some geographic differentiation among populations of M. hirsuta based on chromosomal, morphological, and nuclear and mitochondrial DNA markers, the recognition of new species or subspecies has been avoided due to the need for additional data, mainly chromosomal data. We describe two new cytotypes for Micronycteris hirsuta (MHI) (2n = 26 and 25, NF = 32), whose differences in diploid number are interpreted as the products of Robertsonian rearrangements. C-banding revealed a small amount of constitutive heterochromatin at the centromere and the NOR was located in the interstitial portion of the short arm of a second pair, confirmed by FISH. Telomeric probes hybridized to the centromeric regions and weakly to telomeric regions of most chromosomes. The G-banding analysis and chromosome painting with whole chromosome probes from Carollia brevicauda (CBR) and Phyllostomus hastatus (PHA) enabled the establishment of genome-wide homologies between MHI, CBR and PHA. The karyotypes of Brazilian specimens of Micronycteris hirsuta described here are new to Micronycteris and reinforce that M. hirsuta does not represent a monotypic taxon. Our results corroborate the hypothesis of karyotypic megaevolution within Micronycteris, and strong evidence for this is that the entire chromosome complement of M. hirsuta was shown to be derivative with respect to species compared in this study.
    BMC Genetics 12/2013; 14(1):119. · 2.81 Impact Factor
  • Fumio Kasai, Patricia C M O'Brien, Malcolm A Ferguson-Smith
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    ABSTRACT: Afrotheria genome size is reported to be over 50 per cent larger than that of human, but we show that this is a gross overestimate. Although genome sequencing in Afrotheria is not complete, extensive homology with human has been revealed by chromosome painting. We provide new data on chromosome size and GC content in four Afrotherian species using flow karyotyping. Genome sizes are 4.13Gb in aardvark, 4.01Gb in African elephant, 3.69Gb in golden mole and 3.31Gb in manatee, whereas published results show a mean of 5.18Gb for Afrotheria. Genome GC content shows a negative correlation with size, indicating that this is due to differences in the amount of AT-rich sequence. Low genome GC content and small variance in chromosome GC content are characteristic of aardvark and elephant and may be associated with the high degree of conserved synteny, suggesting that these are features of the Afrotherian ancestral genome.
    Genomics 09/2013; · 3.01 Impact Factor
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    ABSTRACT: Most eukaryotic species represent stable karyotypes with a particular diploid number. B chromosomes are additional to standard karyotypes and may vary in size, number and morphology even between cells of the same individual. For many years it was generally believed that B chromosomes found in some plant, animal and fungi species lacked active genes. Recently molecular cytogenetic studies showed the presence of additional copies of protein-coding genes on B chromosomes. However, the transcriptional activity of these genes remained elusive. We studied karyotypes of the Siberian roe deer (Capreolus pygargus) that possess up to 14 B chromosomes to investigate the presence and expression of genes on supernumerary chromosomes. Here we describe a 2 Mbp region homologous to cattle chromosome 3 and containing TNNI3K (partial), FPGT, LRRIQ3 and a large gene-sparse segment on B chromosomes of the Siberian roe deer. The presence of the copy of the autosomal region was demonstrated by B specific cDNA analysis, PCR assisted mapping, cattle BAC clones localization and qPCR. By comparative analysis of B-specific and non-B chromosomal sequences we discovered some B chromosome-specific mutations in protein-coding genes, which further enabled the detection of a FPGT-TNNI3K transcript expressed from duplicated genes located on B chromosomes in roe deer fibroblasts. Discovery of a large autosomal segment in all B chromosomes of the Siberian roe deer further corroborates the view of autosomal origin of these elements. Detection of a B-derived transcript in fibroblasts implies that the protein coding sequences located on Bs are not fully inactivated. The origin, evolution and effect on host of B chromosomal genes seem to be similar to autosomal segmental duplications, which reinforces the view that supernumerary chromosomal elements might play an important role in genome evolution.
    BMC Biology 08/2013; 11(1):90. · 7.43 Impact Factor
  • Fumio Kasai, Patricia C M O'Brien, Malcolm A Ferguson-Smith
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    ABSTRACT: Bats are distinct from other mammals in their small genome size as well as their high metabolic rate, possibly related to flight ability. Although the genome sequence has been published in two species, the data lack cytogenetic information. In this study, the size and GC content of each chromosome are measured from the flow karyotype of the mouse-eared bat, Myotis myotis (MMY). The smaller chromosomes are GC-rich compared to the larger chromosomes, and the relative proportions of homologous segments between MMY and human differ among the MMY chromosomes. The MMY genome size calculated from the sum of the chromosome sizes is 2.25 Gb, and the total GC content is 42.3 %, compared to human and dog with 41.0 and 41.2 %, respectively. The GC-rich small MMY genome is characterised by GC-biased smaller chromosomes resulting from preferential loss of AT-rich sequences. Although the association between GC-rich small chromosomes and small genome size has been reported only in birds so far, we show in this paper, for the first time, that the same phenomenon is observed in at least one group of mammals, implying that this may be a mechanism common to genome evolution in general.
    Chromosoma 07/2013; · 3.34 Impact Factor
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    ABSTRACT: The Leporinus genus, belonging to the Anostomidae family, is an interesting model for studies of sex chromosome evolution in fish, particularly because of the presence of heteromorphic sex chromosomes only in some species of the genus. In this study we used W chromosome-derived probes in a series of cross species chromosome painting experiments to try to understand events of sex chromosome evolution in this family. W chromosome painting probes from Leporinus elongatus, L. macrocephalus and L. obtusidens were hybridized to each others chromosomes. The results showed signals along their W chromosomes and the use of L. elongatus W probe against L. macrocephalus and L. obtusidens also showed signals over the Z chromosome. No signals were observed when the later aforementioned probe was used in hybridization procedures against other four Anostomidae species without sex chromosomes. Our results demonstrate a common origin of sex chromosomes in L. elongatus, L. macrocephalus and L. obtusidens but suggest that the L. elongatus chromosome system is at a different evolutionary stage. The absence of signals in the species without differentiated sex chromosomes does not exclude the possibility of cryptic sex chromosomes, but they must contain other Leporinus W sequences than those described here.
    BMC Genetics 07/2013; 14(1):60. · 2.81 Impact Factor
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    ABSTRACT: Rodentia comprises 42 % of living mammalian species. The taxonomic identification can be difficult, the number of species currently known probably being underestimated, since many species show only slight morphological variations. Few studies surveyed the biodiversity of species, especially in the Amazon region. Cytogenetic studies show great chromosomal variability in rodents, with diploid numbers ranging from 10 to 102, making it difficult to find chromosomal homologies by comparative G banding. Chromosome painting is useful, but only a few species of rodents have been studied by this technique. In this study, we sorted whole chromosome probes by fluorescence-activated cell sorting from two Hylaeamys megacephalus individuals, an adult female (2n = 54) and a fetus (2n = 50). We made reciprocal chromosome painting between these karyotypes and cross-species hybridization on Cerradomys langguthi (2n = 46). Both species belong to the tribe Oryzomyini (Sigmodontinae), which is restricted to South America and were collected in the Amazon region. Twenty-four chromosome-specific probes from the female and 25 from the fetus were sorted. Reciprocal chromosome painting shows that the karyotype of the fetus does not represent a new cytotype, but an unbalanced karyotype with multiple rearrangements. Cross-species hybridization of H. megacephalus probes on metaphases of C. langguthi shows that 11 chromosomes of H. megacephalus revealed conserved synteny, 10 H. megacephalus probes hybridized to two chromosomal regions and three hybridized to three regions. Associations were observed on chromosomes pairs 1-4 and 11. Fluorescence in situ hybridization with a telomeric probe revealed interstitial regions in three pairs (1, 3, and 4) of C. langguthi chromosomes. We discuss the genomic reorganization of the C. langguthi karyotype.
    Chromosome Research 03/2013; · 2.85 Impact Factor
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    Journal of Investigative Dermatology 01/2013; · 6.19 Impact Factor
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    ABSTRACT: Gymnotus (Gymnotiformes, Gymnotidae) is the most diverse known Neotropical electric knife fish genus. Cytogenetic studies in Gymnotus demonstrate a huge karyotypic diversity for this genus, with diploid numbers ranging from 34 to 54. The NOR are also variable in this genus, with both single and multiple NORs described. A common interpretation is that the single NOR pair is a primitive trait while multiple NORs are derivative. However this hypothesis has never been fully tested. In this report we checked if the NOR-bearing chromosome and the rDNA site are homeologous in different species of the genus Gymnotus: G. carapo (2n = 40, 42, 54), G. mamiraua (2n = 54), G. arapaima (2n = 44), G. sylvius (2n = 40), G. inaequilabiatus (2n = 54) and G. capanema (2n = 34), from the monophyletic group G. carapo (Gymnotidae-Gymnotiformes), as well as G. jonasi (2n = 52), belonging to the G1 group. They were analyzed with Fluorescence in situ hybridization (FISH) using 18S rDNA and whole chromosome probes of the NOR-bearing chromosome 20 (GCA20) of G. carapo (cytotype 2n = 42), obtained by Fluorescence Activated Cell Sorting. All species of the monophyletic G. carapo group show the NOR in the same single pair, confirmed by hybridization with CGA20 whole chromosome probe. In G. jonasi the NORs are multiple, and located on pairs 9, 10 and 11. In G. jonasi the GCA20 chromosome probe paints the distal half of the long arm of pair 7, which is not a NOR-bearing chromosome. Thus these rDNA sequences are not always in the homeologous chromosomes in different species thus giving no support to the hypothesis that single NOR pairs are primitive traits while multiple NORs are derived. The separation of groups of species in the genus Gymnotus proposed by phylogenies with morphologic and molecular data is supported by our cytogenetic data.
    PLoS ONE 01/2013; 8(2):e55608. · 3.53 Impact Factor
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    ABSTRACT: Buteoninae (Falconiformes, Accipitridae) consist of the widely distributed genus Buteo, and several closely related species in a group called "sub-buteonine hawks", such as Buteogallus, Parabuteo, Asturina, Leucopternis and Busarellus, with unsolved phylogenetic relationships. Diploid number ranges between 2n = 66 and 2n = 68. Only one species, L. albicollis had its karyotype analyzed by molecular cytogenetics. The aim of this study was to present chromosomal analysis of three species of Buteoninae: Rupornis magnirostris, Asturina nitida and Buteogallus meridionallis using fluorescence in situ hybridization (FISH) experiments with telomeric and rDNA probes, as well as whole chromosome probes derived from Gallus gallus and Leucopternis albicollis. The three species analyzed herein showed similar karyotypes, with 2n = 68. Telomeric probes showed some interstitial telomeric sequences, which could be resulted by fusion processes occurred in the chromosomal evolution of the group, including the one found in the tassociation GGA1p/GGA6. In fact, this association was observed in all the three species analyzed in this paper, and also in L. albicollis, suggesting that it represents a cytogenetic signature which reinforces the monophyly of Neotropical buteoninae species.
    PLoS ONE 01/2013; 8(7):e70071. · 3.53 Impact Factor
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    Karen Ventura, Yatiyo Yonenaga-Yassuda, Malcolm A Ferguson-Smith
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    ABSTRACT: The Akodontini is the second most speciose tribe of sigmodontine rodents, one of the most diverse groups of neotropical mammals. Molecular phylogenetic analyses are discordant regarding the interrelationships of genera, with low support for some clades. However, two clades are concordant, one (clade A) with Akodon sensu strictu (excluding Akodon serrensis), "Akodon" serrensis, Bibimys, Deltamys, Juscelinomys, Necromys, Oxymycterus, Podoxymys, Thalpomys and Thaptomys, and another (clade B) with Blarinomys, Brucepattersonius, Kunsia, Lenoxus and Scapteromys. Here, we present chromosome painting using Akodon paranaensis (APA) Y paint, after suppression of simple repetitive sequences, on ten Akodontini genera. Partial Y chromosome homology, in addition to the homology already reported on the Akodon genus, was detected on the Y chromosomes of "A." serrensis, Thaptomys, Deltamys, Necromys and Thalpomys and on Y and X chromosomes in Oxymycterus. In Blarinomys, Brucepattersonius, Scapteromys and Kunsia, no APA Y signal was observed using different hybridization conditions; APA X paint gave positive signals only on the X chromosome in all genera. The Y chromosome homology was variable in size and positioning among the species studied as follow: (1) whole acrocentric Y chromosome in Akodon and "A." serrensis, (2) Yp and pericentromeric region in submetacentric Y of Necromys and Thaptomys, (3) pericentromeric region in acrocentric Y of Deltamys, (4) distal Yq in the acrocentric Y chromosome of Thalpomys and (5) proximal Yq in the acrocentric Y and Xp in the basal clade A genus Oxymycterus. The results suggest that the homology involves pairing (pseudoautosomal) and additional regions that have undergone rearrangement during divergence. The widespread Y homology represents a phylogenetic signal in Akodontini that provides additional evidence supporting the monophyly of clade A. The findings also raise questions about the evolution of the pseudoautosomal region observed in Oxymycterus. The Y chromosomes of these closely related species seem to have undergone dynamic rearrangements, including restructuring and reduction of homologous segments. Furthermore, the changes observed may indicate progressive attrition of the Y chromosome in more distantly related species.
    Chromosome Research 06/2012; 20(4):427-33. · 2.85 Impact Factor
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    ABSTRACT: In contrast to mammals, birds exhibit a slow rate of chromosomal evolution. It is not clear whether high chromosome conservation is an evolutionary novelty of birds or was inherited from an earlier avian ancestor. The evolutionary conservatism of macrochromosomes between birds and turtles supports the latter possibility; however, the rate of chromosomal evolution is largely unknown in other sauropsids. In squamates, we previously reported strong conservatism of the chromosomes syntenic with the avian Z, which could reflect a peculiarity of this part of the genome. The chromosome 1 of iguanians and snakes is largely syntenic with chromosomes 3, 5 and 7 of the avian ancestral karyotype. In this project, we used comparative chromosome painting to determine how widely this synteny is conserved across nine families covering most of the main lineages of Squamata. The results suggest that the association of the avian ancestral chromosomes 3, 5 and 7 can be dated back to at least the early Jurassic and could be an ancestral characteristic for Unidentata (Serpentes, Iguania, Anguimorpha, Laterata and Scinciformata). In Squamata chromosome conservatism therefore also holds for the parts of the genome which are homologous to bird autosomes, and following on from this, a slow rate of chromosomal evolution could be a common characteristic of all sauropsids. The large evolutionary stasis in chromosome organization in birds therefore seems to be inherited from their ancestors, and it is particularly striking in comparison with mammals, probably the only major tetrapod lineage with an increased rate of chromosomal rearrangements as a whole.
    Chromosoma 05/2012; 121(4):409-18. · 3.34 Impact Factor
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    Fumio Kasai, Patricia C M O'Brien, Malcolm A Ferguson-Smith
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    ABSTRACT: The genome size in turtles and crocodiles is thought to be much larger than the 1.2 Gb of the chicken (Gallus gallus domesticus, GGA), according to the animal genome size database. However, GGA macrochromosomes show extensive homology in the karyotypes of the red eared slider (Trachemys scripta elegans, TSC) and the Nile crocodile (Crocodylus niloticus, CNI), and bird and reptile genomes have been highly conserved during evolution. In this study, size and GC content of all chromosomes are measured from the flow karyotypes of GGA, TSC and CNI. Genome sizes estimated from the total chromosome size demonstrate that TSC and CNI are 1.21 Gb and 1.29 Gb, respectively. This refines previous overestimations and reveals similar genome sizes in chicken, turtle and crocodile. Analysis of chromosome GC content in each of these three species shows a higher GC content in smaller chromosomes than in larger chromosomes. This contrasts with mammals and squamates in which GC content does not correlate with chromosome size. These data suggest that a common ancestor of birds, turtles and crocodiles had a small genome size and a chromosomal size-dependent GC bias, distinct from the squamate lineage.
    Biology letters 04/2012; 8(4):631-5. · 3.35 Impact Factor
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    ABSTRACT: Devil facial tumour disease (DFTD) is a fatal, transmissible malignancy that threatens the world's largest marsupial carnivore, the Tasmanian devil, with extinction. First recognised in 1996, DFTD has had a catastrophic effect on wild devil numbers, and intense research efforts to understand and contain the disease have since demonstrated that the tumour is a clonal cell line transmitted by allograft. We used chromosome painting and gene mapping to deconstruct the DFTD karyotype and determine the chromosome and gene rearrangements involved in carcinogenesis. Chromosome painting on three different DFTD tumour strains determined the origins of marker chromosomes and provided a general overview of the rearrangement in DFTD karyotypes. Mapping of 105 BAC clones by fluorescence in situ hybridisation provided a finer level of resolution of genome rearrangements in DFTD strains. Our findings demonstrate that only limited regions of the genome, mainly chromosomes 1 and X, are rearranged in DFTD. Regions rearranged in DFTD are also highly rearranged between different marsupials. Differences between strains are limited, reflecting the unusually stable nature of DFTD. Finally, our detailed maps of both the devil and tumour karyotypes provide a physical framework for future genomic investigations into DFTD.
    PLoS Genetics 02/2012; 8(2):e1002483. · 8.52 Impact Factor
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    ABSTRACT: Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6.
    Chromosome Research 10/2011; 19(7):843-55. · 2.85 Impact Factor
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    ABSTRACT: The Rattini (Muridae, Murinae) includes the biologically important model species Rattus norvegicus (RNO) and represents a group of rodents that are of clinical, agricultural and epidemiological importance. We present a comparative molecular cytogenetic investigation of ten Rattini species representative of the genera Maxomys, Leopoldamys, Niviventer, Berylmys, Bandicota and Rattus using chromosome banding, cross-species painting (Zoo-fluorescent in situ hybridization or FISH) and BAC-FISH mapping. Our results show that these taxa are characterised by slow to moderate rates of chromosome evolution that contrasts with the extensive chromosome restructuring identified in most other murid rodents, particularly the mouse lineage. This extends to genomic features such as NOR location (for example, NORs on RNO 3 are present on the corresponding chromosomes in all species except Bandicota savilei and Niviventer fulvescens, and the NORs on RNO 10 are conserved in all Rattini with the exception of Rattus). The satellite I DNA family detected and characterised herein appears to be taxon (Rattus) specific, and of recent origin (consistent with a feedback model of satellite evolution). BAC-mapping using clones that span regions responsible for the morphological variability exhibited by RNO 1, 12 and 13 (acrocentric/submetacentric) and their orthologues in Rattus species, demonstrated that the differences are most likely due to pericentric inversions as exemplified by data on Rattus tanezumi. Chromosomal characters detected using R. norvegicus and Maxomys surifer whole chromosome painting probes were mapped to a consensus sequence-based phylogenetic tree thus allowing an objective assessment of ancestral states for the reconstruction of the putative Rattini ancestral karyotype. This is thought to have comprised 46 chromosomes that, with the exception of a single pair of metacentric autosomes, were acrocentric in morphology.
    Chromosome Research 08/2011; 19(6):709-27. · 2.85 Impact Factor
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    ABSTRACT: The divergence of lineages leading to extant squamate reptiles (lizards, snakes, and amphisbaenians) and birds occurred about 275 million years ago. Birds, unlike squamates, have karyotypes that are typified by the presence of a number of very small chromosomes. Hence, a number of chromosome rearrangements might be expected between bird and squamate genomes. We used chromosome-specific DNA from flow-sorted chicken (Gallus gallus) Z sex chromosomes as a probe in cross-species hybridization to metaphase spreads of 28 species from 17 families representing most main squamate lineages and single species of crocodiles and turtles. In all but one case, the Z chromosome was conserved intact despite very ancient divergence of sauropsid lineages. Furthermore, the probe painted an autosomal region in seven species from our sample with characterized sex chromosomes, and this provides evidence against an ancestral avian-like system of sex determination in Squamata. The avian Z chromosome synteny is, therefore, conserved albeit it is not a sex chromosome in these squamate species.
    Chromosoma 07/2011; 120(5):455-468. · 3.34 Impact Factor

Publication Stats

2k Citations
475.58 Total Impact Points

Institutions

  • 1993–2014
    • University of Cambridge
      • • Department of Veterinary Medicine
      • • Department of Pathology
      Cambridge, England, United Kingdom
  • 2013
    • Instituto Evandro Chagas
      Ananindeua, Pará, Brazil
    • University Hospital Medical Information Network
      Edo, Tōkyō, Japan
  • 2009–2012
    • University of São Paulo
      • Departamento de Genética e Biologia Evolutiva (IB) (Sao Paulo)
      Ribeirão Preto, Estado de Sao Paulo, Brazil
    • Kunming Institute of Zoology CAS
      • State Key Laboratory of Genetic Resources and Evolution
      Kunming, Yunnan, China
  • 2003–2012
    • Australian National University
      • Research School of Biology
      Canberra, Australian Capital Territory, Australia
  • 2011
    • Institute Of Molecular And Cellular Biology SB RAS
      Novo-Nikolaevsk, Novosibirsk, Russia
  • 2010
    • Federal University of Pará
      • Institute of Biological Sciences (ICB)
      Belém, Estado do Para, Brazil
  • 2007–2009
    • Russian Academy of Sciences
      Moskva, Moscow, Russia
  • 2007–2008
    • Institute of Cytology and Genetics
      Novo-Nikolaevsk, Novosibirsk, Russia
  • 2002–2008
    • Northeast Institute of Geography and Agroecology
      • Key Laboratory for Cellular and Molecular Evolution
      Beijing, Beijing Shi, China
  • 1999
    • University of Alberta
      Edmonton, Alberta, Canada