TY - JOUR A1 - Matsuda, Yoichi A1 - Uno, Yoshinobu A1 - Kondo, Mariko A1 - Gilchrist, Michael J. A1 - Zorn, Aaron M. A1 - Rokhsar, Daniel S. A1 - Schmid, Michael A1 - Taira, Masanori T1 - A New Nomenclature of Xenopus laevis Chromosomes Based on the Phylogenetic Relationship to Silurana/Xenopus tropicalis JF - Cytogenetic and Genome Research N2 - Xenopus laevis (XLA) is an allotetraploid species which appears to have undergone whole-genome duplication after the interspecific hybridization of 2 diploid species closely related to Silurana/Xenopus tropicalis (XTR). Previous cDNA fluorescence in situ hybridization (FISH) experiments have identified 9 sets of homoeologous chromosomes in X. laevis, in which 8 sets correspond to chromosomes 1-8 of X. tropicalis (XTR1-XTR8), and the last set corresponds to a fusion of XTR9 and XTR10. In addition, recent X. laevis genome sequencing and BAC-FISH experiments support this physiological relationship and show no gross chromosome translocation in the X. laevis karyotype. Therefore, for the benefit of both comparative cytogenetics and genome research, we here propose a new chromosome nomenclature for X. laevis based on the phylogenetic relationship and chromosome length, i.e. XLA1L, XLA1S, XLA2L, XLA2S, and so on, in which the numbering of XLA chromosomes corresponds to that in X. tropicalis and the postfixes ‘L' and ‘S' stand for ‘long' and ‘short' chromosomes in the homoeologous pairs, which can be distinguished cytologically by their relative size. The last chromosome set is named XLA9L and XLA9S, in which XLA9 corresponds to both XTR9 and XTR10, and hence, to emphasize the phylogenetic relationship to X. tropicalis, XLA9_10L and XLA9_10S are also used as synonyms. KW - BrdU replication banding pattern KW - homoeologous chromosomes KW - nomenclature KW - Xenopus laevis KW - Xenopus tropicalis Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196748 SN - 1424-8581 SN - 1424-859X N1 - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. VL - 145 IS - 3-4 ER - TY - JOUR A1 - Schmid, Michael A1 - Evans, Ben J. A1 - Bogart, James P. T1 - Polyploidy in Amphibia JF - Cytogenetic and Genome Research N2 - This review summarizes the current status of the known extant genuine polyploid anuran and urodelan species, as well as spontaneously originated and/or experimentally produced amphibian polyploids. The mechanisms by which polyploids can originate, the meiotic pairing configurations, the diploidization processes operating in polyploid genomes, the phenomenon of hybridogenesis, and the relationship between polyploidization and sex chromosome evolution are discussed. The polyploid systems in some important amphibian taxa are described in more detail. KW - allopolyploidy KW - Anura KW - autopolyploidy KW - diploidization KW - hybridogenesis KW - polyploidization KW - sex chromosome evolution KW - Urodela Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196730 SN - 1424-8581 SN - 1424-859X N1 - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. VL - 145 IS - 3-4 ER - TY - JOUR A1 - Schmid, Michael A1 - Steinlein, Claus T1 - Chromosome Banding in Amphibia. XXXII. The Genus Xenopus (Anura, Pipidae) JF - Cytogenetic and Genome Research N2 - Mitotic chromosomes of 16 species of the frog genus Xenopus were prepared from kidney and lung cell cultures. In the chromosomes of 7 species, high-resolution replication banding patterns could be induced by treating the cultures with 5-bromodeoxyuridine (BrdU) and deoxythymidine (dT) in succession, and in 6 of these species the BrdU/dT-banded chromosomes could be arranged into karyotypes. In the 3 species of the clade with 2n = 20 and 4n = 40 chromosomes (X. tropicalis, X. epitropicalis, X. new tetraploid 1), as well as in the 3 species with 4n = 36 chromosomes (X. laevis, X. borealis, X. muelleri), the BrdU/dT-banded karyotypes show a high degree of homoeology, though differences were detected between these groups. Translocations, inversions, insertions or sex-specific replication bands were not observed. Minor replication asynchronies found between chromosomes probably involve heterochromatic regions. BrdU/dT replication banding of Xenopus chromosomes provides the landmarks necessary for the exact physical mapping of genes and repetitive sequences. FISH with an X. laevis 5S rDNA probe detected multiple hybridization sites at or near the long-arm telomeric regions in most chromosomes of X. laevis and X. borealis, whereas in X. muelleri, the 5S rDNA sequences are located exclusively at the long-arm telomeres of a single chromosome pair. Staining with the AT base pair-specific fluorochrome quinacrine mustard revealed brightly fluorescing heterochromatic regions in the majority of X. borealis chromosomes which are absent in other Xenopus species. KW - X. laevis-type karyotype KW - X. tropicalis-type karyotype KW - BrdU/dT replication banding KW - chromosome staining KW - FISH KW - polyploidy KW - Xenopus Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196727 SN - 1424-8581 SN - 1424-859X N1 - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. VL - 145 IS - 3-4 ER -