scholarly journals Sequential Steps of Chromosomal Differentiation in Atlantic Surgeonfishes: Evolutionary Inferences

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Paulo Roberto Antunes de Mello Affonso ◽  
Maria Aparecida Fernandes ◽  
Josivanda Santos Almeida ◽  
Wagner Franco Molina
Keyword(s):  
Molecular Phylogeny ◽  
Nucleolar Organizer ◽  
Chromosomal Evolution ◽  
Nucleolar Organizer Regions ◽  
Similar Distribution ◽  
Noncoding Sequences ◽  
Pericentric Inversions ◽  
Chromosomal Differentiation ◽  
Chromosomal Data

Surgeonfishes are a species-rich group and a major biomass on coral reefs. Three species are commonly found throughout South Atlantic,Acanthurus bahianus,A. chirurgus, andA. coeruleus. In this paper, we present the first cytogenetic data of these species, revealing a sequential chromosomal diversification.A. coeruleuswas characterized by a relatively conserved karyotype evolved by pericentric inversions of some pairs (2n=48, 2sm + 4st + 42a). In contrast, the karyotypes ofA. bahianus(2n=36) andA. chirurgus(2n=34) were highly differentiated by the presence of six large metacentric pairs inA. bahianus(12m + 2sm + 4st + 18a) andA. chirurgus(12m + 2sm + 4st +1 6a) probably derived by chromosomal fusions that corroborate their closer relationship. A discerniblein tandemfusion represents an autapomorphic character toA. chirurgus. In spite of macrostructure variation, single nucleolar organizer regions (NORs) on short arms of a subtelocentric pair and similar distribution of C-bands were observed in the three species. Overlapping of chromosomal data with molecular phylogeny indicated pericentric inversions which took place nearly at 19 Ma while centric fusions are as recent as 5 Ma. A physical mapping of coding and noncoding sequences inAcanthuruscould clarify the role of additional rearrangements during their chromosomal 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.

scholarly journals Role of Multiparameter Analysis of AgNORs in FNA Smears of Thyroid Swellings in Differentiating Benign and Malignant Lesions

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Mohammad Ismail Hossain ◽  
Md Quamrul Hassan ◽  
Pradip Bhattacharjee ◽  
M. Shahab Uddin Ahamad ◽  
Zillur Rahman
Keyword(s):  
Nucleolar Organizer ◽  
Cost Effective ◽  
International Committee ◽  
Nucleolar Organizer Regions ◽  
Cost Effective Method ◽  
Staining Protocol ◽  
Size Grade ◽  
Malignant Lesions ◽  
Multiparameter Analysis

Background. The aim of this study is to assess the role of multiparameter analysis of silver (Ag)-stained nucleolar organizer regions (AgNORs) technique on aspiration smears of thyroid swellings to distinguish between benign and malignant lesions. Materials and Methods. Aspiration smears from 166 cases of thyroid swellings were examined. Diagnosis was confirmed by histology in 61 cases. AgNOR staining was done on FNA smears according to silver-staining protocol proposed by the International Committee for AgNOR quantification. Multiparameter analysis of AgNORs such as mAgNOR, pAgNOR, and AgNOR size grade was done on 50–100 cells under oil immersion lens. Results. AgNOR parameter of benign and malignant thyroid lesions was compared and was found to be statistically significant. Out of 157 satisfactory AgNOR stained cases, 148 (94.3%) were benign lesions and 9 (5.7%) cases were malignant lesions. In AgNOR analysis, sensitivity was found to be 83.33%, specificity 100%, PPV 100%, NPV 98.21%, and accuracy was 98.36%. Conclusions. AgNOR analysis in the FNA smears is a simple, sensitive, and cost-effective method for differentiating benign from malignant thyroid swellings.

scholarly journals Cytogenetic analyses in Trinomys (Echimyidae, Rodentia), with description of new karyotypes

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5316 ◽  
Author(s):  
Naiara Pereira Araújo ◽  
Cayo Augusto Rocha Dias ◽  
Rodolfo Stumpp ◽  
Marta Svartman
Keyword(s):  
Chromosome Mapping ◽  
Nucleolar Organizer ◽  
Interspecific Variation ◽  
Nucleolar Organizer Regions ◽  
45S Rdna ◽  
Banding Patterns ◽  
Pericentric Inversions ◽  
Cytogenetic Analyses ◽  
First Time

Trinomys Thomas (1921) is a terrestrial genus of spiny rats endemic to the Brazilian areas of Atlantic Forest and the transitional areas of Cerrado and Caatinga. Although most species have been already karyotyped, the available cytogenetic information is mostly restricted to diploid and fundamental numbers. We analyzed the chromosomes of two Trinomys species: Trinomys moojeni (2n = 56, FN = 106) and Trinomys setosus setosus (2n = 56, FN = 106 and 2n = 56, FN = 108). Our analyses included GTG- and CBG-banding, silver-staining of the nucleolar organizer regions, and chromosome mapping of telomeres and 45S rDNA by fluorescent in situ hybridization (FISH). Comparative GTG- and CBG-banding suggested that the interspecific variation may be due to rearrangements such as pericentric inversions, centromere repositioning, and heterochromatin variation. We report two new karyotypes for T. s. setosus and describe for the first time the banding patterns of the two Trinomys species.

scholarly journals Diversity and chromosomal evolution in the genus Ancistrus Kner, 1854 (Loricariidae: Ancistrini) from three hydrographic basins of Mato Grosso State, Brazil

2013 ◽  
Vol 11 (1) ◽  
pp. 125-131 ◽  
Author(s):  
Sandra Mariotto ◽  
Liano Centofante ◽  
Orlando Moreira-Filho
Keyword(s):  
Diploid Number ◽  
Nucleolar Organizer ◽  
Single Species ◽  
Chromosomal Evolution ◽  
Nucleolar Organizer Regions ◽  
Mitotic Chromosomes ◽  
Evolutionary Mechanisms ◽  
Mato Grosso ◽  
Silver Nitrate Staining ◽  
Cytogenetic Analyses

Cytogenetic analyses were carried out in 117 specimens of seven species of the genus Ancistrus from three hydrographic in Mato Grosso State: Paraguay, Araguaia-Tocantins and Amazon basins. Conventional cytogenetic techniques were used to obtain mitotic chromosomes. C-banding was performed to detect heterochromatic regions and silver nitrate staining was used to identify nucleolar organizer regions (Ag-NORs). The counted and paired chromosomes revealed diploid numbers ranging from 2n = 40 to 2n = 54 with karyotype formulae varying from FN = 80 to FN = 86. Single marks in distinct chromosomes identified the nucleolar organizer regions. The constitutive heterochromatin was scarce in the diploid number from 2n = 50 to 2n = 54 and conspicuous blocks were observed in a single species with 2n = 40 chromosomes. These data corroborate the hypotheses of reduction of diploid number in species with derived features such as presence of sex chromosomes and polymorphisms, besides allowing inferences about the evolutionary mechanisms and the ancestor karyotype that favored the diversification of this important genus in the tribe Ancistrini.

scholarly journals Karyotype Patterns ofHypsolebias antenori(Cyprinodontiformes: Rivulidae): An Endangered Killifish of the Semiarid Region of Brazil

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Wallace Silva do Nascimento ◽  
Juliana Galvão Bezerra ◽  
Paulo Augusto Lima-Filho ◽  
Maria Emília Yamamoto ◽  
Sathyabama Chellappa ◽  
...  
Keyword(s):  
Diploid Number ◽  
Nucleolar Organizer ◽  
Dynamic Environments ◽  
Northeastern Brazil ◽  
Semiarid Region ◽  
Nucleolar Organizer Regions ◽  
Short Life ◽  
Annual Fish ◽  
Pericentric Inversions ◽  
Taxonomic Markers

Annual fish which belong to the order Cyprinodontiformes constitute an excellent model for evolutionary studies. their short life cycle, distribution in ecologically dynamic environments, and low agility make them favorable for genetic analyses. The speciesHypsolebias antenori(Rivulidae), encountered in seasonal pools located in the semiarid region of Northeastern Brazil, has been the object of surveys with a view to study its ecological and behavioral aspects. This study reports on the karyotype patterns of this species, which represents the first contribution to the cytogenetics of this genus. The karyotype of this species is composed of 2n = 48 chromosomes (6m + 4sm + 36st; NF = 96); the heterochromatic regions are located in centromeric or pericentromeric position and are more pronounced in the nucleolar organizer regions. Two sites Ag-NORs/CMA+/DAPI were identified in the short arms of pairs 2 (metacentric) and 21 (subtelocentric). Unlike the other species of this family which show an evolution modulated by events of centric fusions,H. antenorishows the maintenance of a basal diploid number and the large number of bibrachial elements indicates karyotypic diversification derived by pericentric inversions. Cytogenetic analyzes in this species will provide new taxonomic markers capable of being utilized in conservation issues and systematics.

scholarly journals Meiotic imbalance in laboratory-produced hybrid males of Chorthippus parallelus parallelus and Chorthippus parallelus erythropus

1990 ◽  
Vol 56 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J. L. Bella ◽  
G. M. Hewitt ◽  
J. Gosálvez
Keyword(s):  
Hybrid Zone ◽  
Female Parent ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
X Chromosomes ◽  
F1 Hybrid ◽  
Chorthippus Parallelus ◽  
Reciprocal Differences ◽  
Rdna Expression

SummaryThe grasshopper Chorthippus parallelus has two quite distinct subspecies, which meet along the Pyrenees forming a hybrid zone. Using silver staining we show that on the French side Cp. parallelus has three nucleolar organizer regions, on the L2, L3 and X chromosomes, while on the Spanish side Cp. erythropus has only two NORs, on the L2 and L3. Laboratory F1 hybrid males show reciprocal differences in the expression of NORs. When a Cp. erythropus is female parent the male progeny show four active NORs in mitotic cells and two silver precipitates in meiotic cells, as expected. But when a Cp. parallelus female donates the X with a NOR, her male offspring have a variable disrupted nucleolar expression. Some NORs are not expressed and extra sites of cryptic rDNA are revealed. Meiosis is more disturbed in this latter F1 cross with higher levels of polyploidy, but both Fls show around 90% spermatid abnormality. Such variation in rDNA expression is also found in individuals collected from the hybrid zone, and the role of this disturbance in affecting fitness is discussed.

scholarly journals Genome Organization in and around the Nucleolus

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 579 ◽  
Author(s):  
Cristiana Bersaglieri ◽  
Raffaella Santoro
Keyword(s):  
Cell Fate ◽  
Ribosome Biogenesis ◽  
Genome Stability ◽  
Nuclear Lamina ◽  
Nucleolar Organizer ◽  
Rrna Genes ◽  
Nucleolar Organizer Regions ◽  
Rrna Gene ◽  
Fate Decision

The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and transcriptional states—silent, inactive and active. Increasing evidence indicates that the role of the nucleolus and rRNA genes goes beyond the control of ribosome biogenesis. Recent results highlighted the nucleolus as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we aim to describe the crosstalk between the nucleolus and the rest of the genome and how distinct rRNA gene chromatin states affect nucleolus structure and are implicated in genome stability, genome architecture, and cell fate decision.

Cytogenetic studies in North American minnows (Cyprinidae). XXII. Chromosomal nucleolar organizer regions in the genus Pimephales

1991 ◽  
Vol 69 (11) ◽  
pp. 2826-2830 ◽  
Author(s):  
Yucheng Li ◽  
John R. Gold
Keyword(s):  
North American ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Submetacentric Chromosome ◽  
The North ◽  
Extant Species ◽  
Previous Hypothesis ◽  
Chromosomal Data

Chromosomal nucleolar organizer region (NOR) phenotypes are documented for all four extant species in the North American cyprinid fish genus Pimephales. All four species (P. notatus, P. promelas, P. tenellus, and P. vigilax) possess 2n = 50 chromosomes and a pair of NOR-bearing chromosomes with the NOR situated terminally on the short arm of a medium-sized to large submetacentric chromosome (NOR phenotype C). Trypsin G-banding demonstrated that the C NOR chromosome in all four species is homologous. Two of the species (P. tenellus and P. promelas) also possess a C′ NOR chromosome, which is defined as an NOR situated terminally on the short arm of a large submetacentric chromosome that is also the largest chromosome in the complement. The C′ NOR chromosome occurs infrequently in P. promelas, being found in only 8% or so of all metaphases examined. Trypsin G-banding demonstrated that the C′ NOR chromosomes in the two Pimephales species are homologous to one another and to the C′ NOR chromosomes found in the cyprinid genus Cyprinella. A presumed derivative of the C′ NOR chromosome occurs in the monotypic cyprinid genus Opsopoeodus. The NOR chromosomal data support monophyly of the four extant species of Pimephales, and further suggest that the genus Pimephales belongs in a monophyletic assemblage with, among others, the cyprinid genera Cyprinella and Opsopoeodus. The data do not support the previous hypothesis that Pimephales is a basal clade outside of a larger assemblage of "Notropis"-like, shiners.

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