The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Antonio Sánchez - One of the best experts on this subject based on the ideXlab platform.
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Extensive Sex Chromosome Polymorphism of Microtus thomasi/Microtus atticus Species Complex Associated with Cryptic Chromosomal Rearrangements and Independent Accumulation of Heterochromatin.
Cytogenetic and genome research, 2017Co-Authors: Michail Rovatsos, Juan A. Marchal, Ismael Romero-fernández, María Arroyo, Eva B. Athanasopoulou, Antonio SánchezAbstract:The sibling species Microtus thomasi and M. atticus represent probably the highest karyotypic diversity within the genus Microtus and are an in
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a new pericentromeric repeated dna sequence in Microtus thomasi
Cytogenetic and Genome Research, 2009Co-Authors: M J Acosta, Michail Rovatsos, Juan A. Marchal, George P Mitsainas, C H Fernandezespartero, Eva B Giagiaathanasopoulou, Antonio SánchezAbstract:Several karyotypic forms have been previously described in populations of the vole species Microtus thomasi from Greece. In particular, the karyomorphs Microtus thomasi<
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X chromosome painting in Microtus: Origin and evolution of the giant sex chromosomes
Chromosome Research, 2004Co-Authors: J. A. Marchal, Manuel J. Acosta, H. Nietzel, K. Sperling, M. Bullejos, R. Díaz De La Guardia, Antonio SánchezAbstract:Sex chromosomes in species of the genus Microtus present some characteristic features that make them a very interesting group to study sex chromosome composition and evolution. M. cabrerae and M. agrestis have enlarged sex chromosomes (known as ‘giant sex chromosomes’) due to the presence of large heterochromatic blocks. By chromosome microdissection, we have generated probes from the X chromosome of both species and hybridized on chromosomes from six Microtus and one Arvicola species. Our results demonstrated that euchromatic regions of X chromosomes in Microtus are highly conserved, as occurs in other mammalian groups. The sex chromosomes heterochromatic blocks are probably originated by fast amplification of different sequences, each with an independent origin and evolution in each species. For this reason, the sex heterochromatin in Microtus species is highly heterogeneous within species (with different composition for the Y and X heterochromatic regions in M. cabrerae ) and between species (as the composition of M. agrestis and M. cabrerae sex heterochromatin is different). In addition, the X chromosome painting results on autosomes of several species suggest that, during karyotypic evolution of the genus Microtus , some rearrangements have probably occurred between sex chromosomes and autosomes.
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Mapping the SRY gene in Microtus cabrerae: a vole species with multiple SRY copies in males and females.
Genome, 2002Co-Authors: Rosa Fernández, M. Bullejos, María J. López Barragán, Juan Alberto Marchal, S. Martínez, Rafael Díaz De La Guardia, Antonio SánchezAbstract:The SRY gene is a single-copy, male-specific gene, located on the Y chromosome in most mammals. However, recently we have described the presence of multiple polymorphic copies of this gene in both males and females of the vole species Microtus cabrerae. Here, we present the chromosomal localization of SRY gene copies in this species by fluorescent in situ hybridization (FISH). This technique localized these gene copies in the short arm, and hence in the euchromatic region, of the Y chromosome. Furthermore, several copies of the SRY gene are located on the X chromosome. These copies are spread along the entire heterochromatic region of the X chromosome, occupying the whole short arm, the centromeric region, and the pericentromeric region of the long arm.Key words: FISH mapping, Micotus cabrerae, SRY gene, X chromosome, Y chromosome.
Baizhong Cui - One of the best experts on this subject based on the ideXlab platform.
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Genetics of Metabolic Variations between Yersinia pestis Biovars and the Proposal of a New Biovar, Microtus
Journal of bacteriology, 2004Co-Authors: Dongsheng Zhou, Zongzhong Tong, Yajun Song, Yanping Han, Decui Pei, Xin Pang, Junhui Zhai, Baizhong CuiAbstract:Yersinia pestis has been historically divided into three biovars: antiqua, mediaevalis, and orientalis. On the basis of this study, strains from Microtus-related plague foci are proposed to constitute a new biovar, Microtus. Based on the ability to ferment glycerol and arabinose and to reduce nitrate, Y. pestis strains can be assigned to one of four biovars: antiqua (glycerol positive, arabinose positive, and nitrate positive), mediaevalis (glycerol positive, arabinose positive, and nitrate negative), orientalis (glycerol negative, arabinose positive, and nitrate positive), and Microtus (glycerol positive, arabinose negative, and nitrate negative). A 93-bp in-frame deletion in glpD gene results in the glycerol-negative characteristic of biovar orientalis strains. Two kinds of point mutations in the napA gene may cause the nitrate reduction-negative characteristic in biovars mediaevalis and Microtus, respectively. A 122-bp frameshift deletion in the araC gene may lead to the arabinose-negative phenotype of biovar Microtus strains. Biovar Microtus strains have a unique genomic profile of gene loss and pseudogene distribution, which most likely accounts for the human attenuation of this new biovar. Focused, hypothesis-based investigations on these specific genes will help delineate the determinants that enable this deadly pathogen to be virulent to humans and give insight into the evolution of Y. pestis and plague pathogenesis. Moreover, there may be the implications for development of biovar Microtus strains as a potential vaccine.
Basil Chondropoulos - One of the best experts on this subject based on the ideXlab platform.
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molecular phylogeny of the speciose vole genus Microtus arvicolinae rodentia inferred from mitochondrial dna sequences
Molecular Phylogenetics and Evolution, 2004Co-Authors: Maarit Jaarola, Natalia Martinkova, Islam Gunduz, Cecilia Brunhoff, Jan Zima, Adam Nadachowski, Giovanni Amori, Nina Bulatova, Basil ChondropoulosAbstract:Voles of the genus Microtus represent one of the most speciose mammalian genera in the Holarctic. We established a molecular phylogeny for Microtus to resolve contentious issues of systematic relationships and evolutionary history in this genus. A total of 81 specimens representing ten Microtus species endemic to Europe as well as eight Eurasian, six Asian and one Holarctic species were sequenced for the entire cytochrome b gene (1140 bp). A further 25 sequences were retrieved from GenBank, providing data on an additional 23, mainly Nearctic, Microtus species. Phylogenetic analysis of these 48 species generated four well-supported monophyletic lineages. The genus Chionomys, snow voles, formed a distinct and well-supported lineage separate from the genus Microtus. The subgenus Microtus formed the strongest supported lineage with two sublineages displaying a close relationship between the arvalis species group (common voles) and the socialis species group (social voles). Monophyly of the Palearctic pitymyid voles, subgenus Terricola, was supported, and this subgenus was also subdivided into two monophyletic species groups. Together, these groupings clarify long-standing taxonomic uncertainties in Microtus. In addition, the "Asian" and the Nearctic lineages reported previously were identified although the latter group was not supported. However, relationships among the main Microtus branches were not resolved, suggesting a rapid and potentially simultaneous radiation of a widespread ancestor early in the history of the genus. This and subsequent radiations discernible in the cytochrome b phylogeny, show the considerable potential of Microtus for analysis of historical and ecological determinants of speciation in small mammals. It is evident that speciation is an ongoing process in the genus and that the molecular data provides a vital insight into current species limits as well as cladogenic events of the past.
Islam Gunduz - One of the best experts on this subject based on the ideXlab platform.
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molecular phylogeny of the speciose vole genus Microtus arvicolinae rodentia inferred from mitochondrial dna sequences
Molecular Phylogenetics and Evolution, 2004Co-Authors: Maarit Jaarola, Natalia Martinkova, Islam Gunduz, Cecilia Brunhoff, Jan Zima, Adam Nadachowski, Giovanni Amori, Nina Bulatova, Basil ChondropoulosAbstract:Voles of the genus Microtus represent one of the most speciose mammalian genera in the Holarctic. We established a molecular phylogeny for Microtus to resolve contentious issues of systematic relationships and evolutionary history in this genus. A total of 81 specimens representing ten Microtus species endemic to Europe as well as eight Eurasian, six Asian and one Holarctic species were sequenced for the entire cytochrome b gene (1140 bp). A further 25 sequences were retrieved from GenBank, providing data on an additional 23, mainly Nearctic, Microtus species. Phylogenetic analysis of these 48 species generated four well-supported monophyletic lineages. The genus Chionomys, snow voles, formed a distinct and well-supported lineage separate from the genus Microtus. The subgenus Microtus formed the strongest supported lineage with two sublineages displaying a close relationship between the arvalis species group (common voles) and the socialis species group (social voles). Monophyly of the Palearctic pitymyid voles, subgenus Terricola, was supported, and this subgenus was also subdivided into two monophyletic species groups. Together, these groupings clarify long-standing taxonomic uncertainties in Microtus. In addition, the "Asian" and the Nearctic lineages reported previously were identified although the latter group was not supported. However, relationships among the main Microtus branches were not resolved, suggesting a rapid and potentially simultaneous radiation of a widespread ancestor early in the history of the genus. This and subsequent radiations discernible in the cytochrome b phylogeny, show the considerable potential of Microtus for analysis of historical and ecological determinants of speciation in small mammals. It is evident that speciation is an ongoing process in the genus and that the molecular data provides a vital insight into current species limits as well as cladogenic events of the past.
Sen-ichi Oda - One of the best experts on this subject based on the ideXlab platform.
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Karyotype and X–Y chromosome pairing in the Sikkim vole (Microtus (Neodon) sikimensis)
Journal of Zoology, 2002Co-Authors: Kazuyuki Mekada, Kazuhiro Koyasu, Masashi Harada, Yuichi Narita, Krishna C. Shrestha, Sen-ichi OdaAbstract:Pairing of the X and Y chromosomes during meiotic prophase and the G- and C-banding patterns were analysed in Microtus sikimensis. The karyotype of M. sikimensis from central Nepal, has 2n = 48 and FNa = 56. It has been derived from the all single-armed karyotype of M. carruthersi through a unique course of evolution. There is a synapsis between the X and Y chromosomes at pachytene and end-to-end association from diakinesis to metaphase I. Microtus sikimensis has no close karyological or morphological relationship to the other synaptic species studied so far. These data confirm that several species or lineages with synaptic condition exist in the genus Microtus, and that the ancestor of Microtus had synaptic sex chromosomes.
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Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii.
Genome, 2001Co-Authors: Kazuyuki Mekada, Kazuhiro Koyasu, Harada M, Pavel M. Borodin, Sen-ichi OdaAbstract:Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic XY chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.Key words: Microtus kikuchii, Microtus phylogeny, karyotype, synaptic sex chromosomes, synaptonemal complex.
