Tandem chromosome fusions in karyotypic evolution of Muntiacus: evidence from M. feae and M. gongshanensis

2006 ◽  
Vol 14 (6) ◽  
pp. 637-647 ◽  
Author(s):  
L. Huang ◽  
J. Wang ◽  
W. Nie ◽  
W. Su ◽  
F. Yang
Keyword(s):  
Karyotypic Evolution ◽  
Chromosome Fusions

Karyotypic Evolution in Gehyra (Gekkonidae: Reptilia) I. The Gehyra Variegata-Punctata Complex.

1979 ◽  
Vol 27 (3) ◽  
pp. 373 ◽  
Author(s):  
M King
Keyword(s):  
Phylogenetic Relationships ◽  
Karyotypic Evolution ◽  
Isolated Populations ◽  
Karyotypic Analysis ◽  
Geographic Barriers ◽  
Chromosome Races ◽  
Chromosome Fusions ◽  
Morphological Differences ◽  
Gehyra Variegata

A karyotypic analysis of populations of the gekkos Gehyra variegata and G. punctata reveals three chromosome races in G. variegata (2n = 44; 2n = 40a; 2n = 40b), and three in G. punctata (2n = 44; 2n = 42; 2n = 38). The chromosome races have differentiated by a series of chromosome fusions. The ordered nature of these changes suggests that the phylogenetic relationships of the races cut across the current taxonomy, and it is argued that there is but one 2n = 44 race, occurring as a number of morphologically distinct populations, two of which were erroneously described as the separate Gehyra species. Isolated populations within a number of the chromosome races show pronounced morphological differences. It is believed that these gekkos are an ancient Australian group which differentiated chromosomally during a number of colonizing radiations. Since then, populations within each race have been isolated by geographic barriers and have speciated allopatrically. This suggests that the chromosome races are at least good species and may be of a higher taxon.

New evidence for tandem chromosome fusions in the karyotypic evolution of Asian muntjacs

Chromosoma ◽  
1991 ◽  
Vol 101 (1) ◽  
pp. 19-24 ◽  
Author(s):  
C. C. Lin ◽  
R. Sasi ◽  
Y. S. Fan ◽  
Z. Q. Chen
Keyword(s):  
Karyotypic Evolution ◽  
Chromosome Fusions ◽  
New Evidence

scholarly journals Genomic dispersion of 28S rDNA during karyotypic evolution in the ant genusMyrmecia (formicidae)

Chromosoma ◽  
1997 ◽  
Vol 105 (6) ◽  
pp. 380-381
Author(s):  
Hiroshisa Hirai ◽  
Masa-Toshi Yamamoto ◽  
Robert W. Taylor ◽  
Hirotami T. Imai
Keyword(s):  
28S Rdna ◽  
Karyotypic Evolution

Diversity and Karyotypic Evolution in the Genus Neacomys (Rodentia, Sigmodontinae)

2015 ◽  
Vol 146 (4) ◽  
pp. 296-305 ◽  
Author(s):  
Willam O. da Silva ◽  
Julio C. Pieczarka ◽  
Rogério V. Rossi ◽  
Horacio Schneider ◽  
Iracilda Sampaio ◽  
...  
Keyword(s):  
Molecular Phylogeny ◽  
Diploid Number ◽  
Constitutive Heterochromatin ◽  
Chromosomal Evolution ◽  
The Other ◽  
Karyotypic Evolution ◽  
Drastic Reduction ◽  
Ancestral Species ◽  
Pericentric Inversions ◽  
Amazonian Region

Neacomys (Sigmodontinae) comprises 8 species mainly found in the Amazonian region. We describe 5 new karyotypes from Brazilian Amazonia: 2 cytotypes for N. paracou (2n = 56/FNa = 62-66), 1 for N. dubosti (2n = 64/FNa = 68), and 2 for Neacomys sp. (2n = 58/FNa = 64-70), with differences in the 18S rDNA. Telomeric probes did not show ITS. We provide a phylogeny using Cytb, and the analysis suggests that 2n = 56 with a high FNa is ancestral for the genus, as found in N. paracou, being retained by the ancestral forms of the other species, with an increase in 2n occurring independently in N. spinosus and N. dubosti. Alternatively, an increase in 2n may have occurred in the ancestral taxon of the other species, followed by independent 2n-reduction events in Neacomys sp. and in the ancestral species of N. tenuipes, N. guianae, N. musseri, and N. minutus. Finally, a drastic reduction event in the diploid number occurred in the ancestral species of N. musseri and N. minutus which exhibit the lowest 2n of the genus. The karyotypic variations found in both intra- and interspecific samples, associated with the molecular phylogeny, suggest a chromosomal evolution with amplification/deletion of constitutive heterochromatin and rearrangements including fusions, fissions, and pericentric inversions.

Karyotypic Evolution in Neotropical Fishes

2007 ◽  
pp. 111-164 ◽  
Author(s):  
Claudio Oliveira ◽  
Lurdes Foresti de Almeida-Toledo ◽  
Fausto Foresti
Keyword(s):  
Karyotypic Evolution ◽  
Neotropical Fishes

scholarly journals Karyotypic evolution of the Medicago complex: sativa-caerulea-falcata inferred from comparative cytogenetic analysis

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Feng Yu ◽  
Haiqing Wang ◽  
Yanyan Zhao ◽  
Ruijuan Liu ◽  
Quanwen Dou ◽  
...  
Keyword(s):  
Cytogenetic Analysis ◽  
Karyotypic Evolution

scholarly journals Epigenetic dynamics of centromeres and neocentromeres in Cryptococcus deuterogattii

PLoS Genetics ◽  
2021 ◽  
Vol 17 (8) ◽  
pp. e1009743
Author(s):  
Klaas Schotanus ◽  
Vikas Yadav ◽  
Joseph Heitman
Keyword(s):  
Dna Methylation ◽  
Transposable Element ◽  
Fungal Pathogen ◽  
Fusion Partner ◽  
Epigenetic Memory ◽  
Chromosome Fusion ◽  
Human Fungal Pathogen ◽  
Chromosome Fusions ◽  
The Impact ◽  
Active Centromere

Deletion of native centromeres in the human fungal pathogen Cryptococcus deuterogattii leads to neocentromere formation. Native centromeres span truncated transposable elements, while neocentromeres do not and instead span actively expressed genes. To explore the epigenetic organization of neocentromeres, we analyzed the distribution of the heterochromatic histone modification H3K9me2, 5mC DNA methylation and the euchromatin mark H3K4me2. Native centromeres are enriched for both H3K9me2 and 5mC DNA methylation marks and are devoid of H3K4me2, while neocentromeres do not exhibit any of these features. Neocentromeres in cen10Δ mutants are unstable and chromosome-chromosome fusions occur. After chromosome fusion, the neocentromere is inactivated and the native centromere of the chromosome fusion partner remains as the sole, active centromere. In the present study, the active centromere of a fused chromosome was deleted to investigate if epigenetic memory promoted the re-activation of the inactive neocentromere. Our results show that the inactive neocentromere is not re-activated and instead a novel neocentromere forms directly adjacent to the deleted centromere of the fused chromosome. To study the impact of transcription on centromere stability, the actively expressed URA5 gene was introduced into the CENP-A bound regions of a native centromere. The introduction of the URA5 gene led to a loss of CENP-A from the native centromere, and a neocentromere formed adjacent to the native centromere location. Remarkably, the inactive, native centromere remained enriched for heterochromatin, yet the integrated gene was expressed and devoid of H3K9me2. A cumulative analysis of multiple CENP-A distribution profiles revealed centromere drift in C. deuterogattii, a previously unreported phenomenon in fungi. The CENP-A-binding shifted within the ORF-free regions and showed a possible association with a truncated transposable element. Taken together, our findings reveal that neocentromeres in C. deuterogattii are highly unstable and are not marked with an epigenetic memory, distinguishing them from native centromeres.

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